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Find video protocols related to scientific articles indexed in Pubmed.
[Particle swarm optimization fuzzy modeling and closed-loop anaesthesia control based on cerebral state index].
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi
PUBLISHED: 09-16-2014
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Due to individual differences of the depth of anaesthesia (DOA) controlled objects, the drawbacks of monitoring index, the traditional PID controller of anesthesia depth could not meet the demands of nonlinear control. However, the adjustments of the rules of DOA fuzzy control often rely on personal experience and, therefore, it could not achieve the satisfactory control effects. The present research established a fuzzy closed-loop control system which takes the cerebral state index (CSI) value as a feedback controlled variable, and it also adopts the particle swarm optimization (PSO) to optimize the fuzzy control rule and membership functions between the change of CSI and propofol infusion rate. The system sets the CSI targets at 40 and 30 through the system simulation, and it also adds some Gaussian noise to imitate clinical disturbance. Experimental results indicated that this system could reach the set CSI point accurately, rapidly and stably, with no obvious perturbation in the presence of noise. The fuzzy controller based on CSI which has been optimized by PSO has better stability and robustness in the DOA closed loop control system.
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Theoretical study for OH radical-initiated atmospheric oxidation of ethyl acrylate.
Chemosphere
PUBLISHED: 08-16-2014
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OH radical-initiated atmospheric oxidation of ethyl acrylate (ethyl 2-propenoate, EA) has been investigated by performing density functional theory (DFT) calculations. Optimizations of the reactants, intermediates, transition states and products were carried out at the MPWB1K/6-31+G(d,p) level. Single-point energy calculations were performed at the MPWB1K/6-311+G(3df,2p) level of theory. The detailed oxidation mechanism was presented and discussed. The results show that the OH addition is more energetically favorable than the H abstraction. Rice-Ramsperger-Kassel-Marcus (RRKM) theory was used to predict the rate constants over the possible atmospheric temperature range of 180-370K. The Arrhenius expression adequately describes the total rate constant: k(EA+OH)=(1.71×10(-12))exp(805.42/T)cm(3)molecule(-1)s(-1). At 298K, the atmospheric lifetime of ethyl acrylate determined by OH radicals is about 16.2h. In order to find out the effect of alkyl substitution on the reaction activity, rate constants for the reactions of methyl acrylate, methyl methacrylate and butyl acrylate with OH radicals were also discussed. Calculation results show that the reaction activity may increase with the increased electron-donating substitution for electrophilic addition reaction.
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[Research progress on application of gold magnetic nanocomposite in biomedicine].
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi
PUBLISHED: 07-22-2014
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This paper provides a brief overview of the current research activities which focused on the bio-application of gold magnetic nanocomposite particles. By combining the magnetic characteristics of the iron oxide core with the unique features of nano-gold particles such as targeting by surface modification and optical properties, such composite nanoparticles have a wide range of applications in cancer hyperthermia, CT and MRI imaging, bio-separation, bio sensors, gene diagnosis, drug targeting and many other biomedical fields.
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Role of water molecule in the gas-phase formation process of nitrated polycyclic aromatic hydrocarbons in the atmosphere: a computational study.
Environ. Sci. Technol.
PUBLISHED: 04-11-2014
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Nitro-PAHs are globally worrisome air pollutants because their high direct-acting mutagenicity and carcinogenicity. A mechanistic understanding of their formation is of crucial importance for successful prevention of their atmospheric pollution. Here, the formation of nitro-PAHs arising from the OH-initiated and NO3-initiated atmospheric reactions of PAHs was investigated by using quantum chemical calculations. It is widely assumed that OH or NO3 radicals attack on the C atoms of the aromatic rings in the PAH molecule, followed by the addition of NO2 to the OH-PAH or NO3-PAH adducts at the ortho position and the loss of water or nitric acid to form nitro-PAHs. However, calculations show that the direct loss of water from the OH-NO2-PAH adducts via the unimolecular decomposition is energetically unfavorable. This study reveals for the first time that water molecule plays an important catalytic effect on the loss of water from the OH-NO2-PAH adducts and promotes the formation of nitro-PAHs. In addition, the introduction of water unwraps new formation pathway through the addition of NO2 to the OH-PAH or NO3-PAH adduct at the para position. The individual and overall rate constants for the addition reactions of PAHs with OH and NO3 radicals were deduced by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory.
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Computational evidence for the detoxifying mechanism of epsilon class glutathione transferase toward the insecticide DDT.
Environ. Sci. Technol.
PUBLISHED: 04-08-2014
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A combined quantum mechanics/molecular mechanics (QM/MM) computation of the detoxifying mechanism of an epsilon class glutathione transferases (GSTs) toward organochlorine insecticide DDT, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, has been carried out. The exponential average barrier of the proton transfer mechanism is 15.2 kcal/mol, which is 27.6 kcal/mol lower than that of the GS-DDT conjugant mechanism. It suggests that the detoxifying reaction proceeds via a proton transfer mechanism where GSH acts as a cofactor rather than a conjugate. The study reveals that the protein environment has a strong effect on the reaction barrier. The experimentally proposed residues Arg112, Glu116 and Phe120 were found to have a strong influence on the detoxifying reaction. The influence of residues Pro13, Cys15, His53, Ile55, Glu67, Ser68, Phe115, and Leu119 was detected as well. It is worth noticing that Ile55 facilitates the detoxifying reaction most. On the basis of the structure of DDT, structure 2, (BrC6H4)2CHCCl3, is the best candidate among all the tested structures in resisting the detoxification of enzyme agGSTe2.
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Mechanistic and kinetic studies on the OH-initiated atmospheric oxidation of fluoranthene.
Sci. Total Environ.
PUBLISHED: 04-02-2014
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The atmospheric oxidation of polycyclic aromatic hydrocarbons (PAHs) can generate toxic derivatives which contribute to the carcinogenic potential of particulate organic matter. In this work, the mechanism of the OH-initiated atmospheric oxidation of fluoranthene (Flu) was investigated by using high-accuracy molecular orbital calculations. All of the possible oxidation pathways were discussed, and the theoretical results were compared with the available experimental observation. The rate constants of the crucial elementary reactions were evaluated by the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The main oxidation products are a range of ring-retaining and ring-opening chemicals containing fluoranthols, fluoranthones, fluoranthenequinones, nitro-fluoranthenes, dialdehydes and epoxides. The overall rate constant of the OH addition reaction is 1.72×10(-11) cm(3) molecule(-1) s(-1) at 298 K and 1 atm. The atmospheric lifetime of Flu determined by OH radicals is about 0.69 days. This work provides a comprehensive investigation of the OH-initiated oxidation of Flu and should help to clarify its atmospheric conversion.
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Mechanism and kinetics study on the ozonolysis reaction of 2,3,7,8-TCDD in the atmosphere.
J Environ Sci (China)
PUBLISHED: 03-22-2014
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The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin (2,3,7,8-TCDD) is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and O3 is 4.80 x 10(-20) cm3/(mole x sec) at 298 K and 760 Torr. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.
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High-resolution profiles of dissolved reactive phosphorus in overlying water and porewater of Lake Taihu, China.
Environ Sci Pollut Res Int
PUBLISHED: 03-21-2014
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The diffusive gradients in thin films (DGT) technique was applied to obtain high spatial resolution of dissolved reactive phosphorus (DRP) concentrations in overlying water and sediment porewater in Lake Taihu. A strong positive correlation between total phosphorus (TP) in sediments and DRP concentrations using DGT was found in both of the sampled lake regions. For stations ZSW and DPG, which have high TP background values in sediments, DRP concentrations in overlying water and porewater were much higher than those at stations MLW, DPG, and HX. Also, a high potential for P release at the sediment-water interface was revealed at stations ZSW and DPG due to a significant concentration gradient between overlying water and porewater. In sediment cores from stations ZSW and DPG, DRP porewater concentration profiles using DGT with three diffusive gel thicknesses displayed a similar trend, increasing down to -2 cm or -4 cm, then decreasing down to -8 cm, and then becoming relatively stable in deeper layers. High-resolution profiles of DRP were related to dissolved oxygen concentrations and organic matter concentrations in different sediment layers at stations ZSW and DPG. For most sediment with low TP concentrations at stations MLW, DPG, and HX, DRP concentrations could not be determined at and near the sediment-water interface, then increased gradually down to -8 cm or -10 cm, and remained stable. At stations MLW, DPG, and HX, most DRPDGT (DRP concentrations measured by DGT) values were 10-30 % of the DRP concentrations in porewater, indicating a partial resupply of the sediments to porewater.
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Mechanistic and kinetic studies on OH-initiated atmospheric oxidation degradation of benzo[?]pyrene in the presence of O2 and NOx.
Chemosphere
PUBLISHED: 03-06-2014
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The degradation of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere can lead to toxic derivatives which contribute to the carcinogenic potential of particulate organic matter. This paper aimed to investigate the mechanism of the OH-initiated oxidation degradation of benzo[?]pyrene (BaP), a cancer risk indicator. High-accuracy molecular orbital calculations were carried out, and all of the possible degradation pathways were discussed. The theoretical results were compared with the available experimental observation. The possible secondary reactions were also investigated. The rate constants of the crucial elementary steps were evaluated by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The dominant degradation products involve benzo[?]pyren-ol, nitro-benzo[?]pyrene, benzo[?]pyrene-7,10-dione as well as several ring-opened products such as alkyl substituted benzanthraldehyde et al. In particular, water plays an important role in the degradation pathways leading to the formation of nitro-benzo[?]pyrene. This work provides a comprehensive investigation of the OH-initiated degradation of BaP and should help to clarify its potential risk.
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Computational study on the mechanisms and rate constants of the OH-initiated oxidation of ethyl vinyl ether in atmosphere.
Chemosphere
PUBLISHED: 02-23-2014
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The hydroxylation reactions of ethyl vinyl ether (EVE) in the present of O2 and NO are analyzed by using MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. According to the calculated thermodynamic data, the detailed reaction mechanisms of EVE and OH are proposed. All of the ten possible reaction pathways are discussed. The major products of the title reaction are ethyl formate and formaldehyde, which is in accordance with experimental detection. The rate constants of the primary reactions over the temperature of 250-400K and the pressure range of 100-2000Torr are computed by employing MESMER program. At 298K and 760Torr, OH-addition channels are predominate and the total rate constant is ktot=4.53×10(-11)cm(3)molecule(-1)s(-1). The Arrhenius equation is obtained as ktot=6.27×10(-12)exp(611.5/T), according to the rate constants given at different temperatures. Finally, the atmospheric half life of EVE with respect to OH is estimated to be 2.13h.
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Micro-mechanism and rate constants for OH-initiated degradation of methomyl in atmosphere.
Chemosphere
PUBLISHED: 01-24-2014
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The atmospheric degradation reactions of the two isomers of methomyl (MTL) initiated by OH radical in the presence of O2, NO and H2O have been investigated by density functional theory (DFT). The calculations were all carried out at MPWB1K level. The geometrical parameters and vibrational frequencies of stationary points were calculated with 6-31+G (d, p) basis sets. Single-point energy calculations were performed with 6-311+G (3df, 2p) basis sets. Profiles of the potential energy surface were constructed and all possible channels involved in the reactions were discussed. The rate constants of main elementary reactions were calculated over a temperature range of 200-400 K and mostly fitted to Arrhenius formulas. The atmospheric lifetimes of reaction species were discussed for the first time, which can be applied to the study on model simulation and management of hazardous materials.
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Severe haze episodes and seriously polluted fog water in Ji'nan, China.
Sci. Total Environ.
PUBLISHED: 01-17-2014
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Haze episodes often hit urban cities in China recently. Here, we present several continuous haze episodes with extremely high PM2.5 levels that occurred over several weeks in early 2013 and extended across most parts of the northern and eastern China-far exceeding the Beijing-Tianjin-Hebei region. Particularly, the haze episode covered ~1 million km(2) on January 14, 2013 and the daily averaged PM2.5 concentration exceeded 360 ?g m(-3) in Ji'nan. The observed maximum hourly PM2.5 concentration in urban Ji'nan reached 701 ?g m(-3) at 7:00 am (local time) in January 30. During these haze episodes, several fog events happened and the concurrent fog water was found to be seriously polluted. For the fog water collected in Ji'nan from 10:00 pm in January 14 to 11:00 am in January 15, sulfate, nitrate, and ammonium were the major ions with concentrations of 1.54 × 10(6), 8.98 × 10(5), and 1.75 × 10(6) ?eq L(-1), respectively, leading to a low in-situ pH of 3.30. The sulfate content in the fog sample was more than 544 times as high as those observed in other areas. With examination of the simultaneously observed data on PM2.5 and its chemical composition, the fog played a role in scavenging and removing fine particles from the atmosphere during haze episodes and thus was seriously contaminated. However, the effect was not sufficient to obviously cleanse air pollution and block haze episodes.
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Arsenic fractionation and contamination assessment in sediments of thirteen lakes from the East Plain and Yungui Plateau Ecoregions, China.
J Environ Sci (China)
PUBLISHED: 01-08-2014
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Arsenic (As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecoregions, followed by reducible As and soluble or oxidizable As. The total As is correlated to oxidizable As and residual As in sediment samples from both lake ecoregions. As distribution in sediment samples of lakes of the East Plain Ecoregion appears to be affected by human activity, while the As origin mainly comes from natural sources in sediment samples of lakes in the Yungui Plateau Ecoregion. The potential ecological risk index and geoaccumulation index values suggest "low to moderate" risk degree and "unpolluted to moderately polluted" for As in the studied lake sediments.
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miR-199a-5p regulates the expression of metastasis-associated genes in B16F10 melanoma cells.
Int J Clin Exp Pathol
PUBLISHED: 01-01-2014
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MicroRNAs are regulatory factors that play important roles in tumor development, invasion and metastasis. Previously, we showed that miR-199a is abnormally expressed in clinical melanoma specimens and expression was closely associated with clinical features of metastasis. However, the exact molecular mechanisms by which miR-199a-5p influences melanoma invasion and metastasis remains unclear. In this study, we investigated gene expression changes of metastasis-associated genes in B16F10 melanoma cells following targeted silencing or overexpression of miR-199a-5p, using mouse tumor metastasis PCR arrays. Comparison of gene expression changes in miR-199a-5p-silenced versus overexpressing cells identified a set of upregulated genes (> 2-fold) including Cd44, Cdh1, Cxcr4, Etv4, Fxyd5, Rpsa, Mmp3, Myc, Rb1, Tcf20, Hprt1, Actb1 and downregulated genes (> 2-fold) including Ctsk, Itga7 and Tnfsf10. Regulation of a subset of these genes (Myc, Tnfsf10 and Cd44) following miR-199a-5p silencing or overexpression was validated by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. In conclusion, our study demonstrates that miR-199a-5p regulates melanoma metastasis-related genes, and may provide a basis for the development of novel, molecularly targeted drugs.
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ERCC1 Cys8092Ala and XRCC1 Arg399Gln polymorphisms predict progression-free survival after curative radiotherapy for nasopharyngeal carcinoma.
PLoS ONE
PUBLISHED: 01-01-2014
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Single nucleotide polymorphisms (SNPs) in DNA repair genes can alter gene expression and activity and affect response to cancer treatment and, correspondingly, survival. The present study was designed to evaluate the utility of the XRCC1 Arg399Gln and ERCC1 Cys8092Ala SNPs, measured in pretreatment biopsy samples, as predictors of response to radiotherapy in patients with non-metastatic nasopharyngeal carcinoma (NPC).
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Characterization, treatment and releases of PBDEs and PAHs in a typical municipal sewage treatment plant situated beside an urban river, East China.
J Environ Sci (China)
PUBLISHED: 11-14-2013
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Characterization, treatment and releases of eight polybrominated diphenyl ethers (PBDEs) congeners and sixteen polycyclic aromatic hydrocarbons (PAHs) in wastewater were evaluated along the treatment processes of a typical secondary treatment municipal sewage treatment plant (STP) (in Hefei City) situated the beside Nanfei River, East China. The findings showed that the average concentrations of the total PBDEs in raw wastewater and treated effluent were 188.578 and 36.884 ng/L respectively. Brominated diphenyl ether (BDE) 209 congener, the predominant PBDE in the STP and Nanfei River, could be related to the discharge of car-industry-derived wastes. For PAHs, the average concentrations in raw wastewater and treated effluent were 5758.8 and 2240.4 ng/L respectively, with naphthalene, benzo[a]pyrene and indeno[1,2,3-c,d]pyrene being detected at the highest concentrations. PAHs mainly originate from the combustion of biomass/coal and petroleum. The STP reduced about 80% of the PBDEs and 61% of the PAHs, which were eliminated mainly by sedimentation processes. The removal rates of PBDEs/PAHs increased with the increase of their solid-water partitioning coefficients. Accordingly, the STPs effluent, containing some PBDE congeners (e.g., BDE 47, 99 and 209, etc.) and low-molecular-weight PAHs, could be an important contributor of these contaminants input to Nanfei River. It resulted in a significant increase of PBDE/PAH concentrations and PAH toxicological risk in the river water downstream. About 4.040 kg/yr of PBDEs and 245.324 kg/yr of PAHs could be released into the Nanfei River. The current conventional wastewater treatment processes should be improved to remove the relatively low-molecular-weight PBDEs/PAHs more effectively.
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Polybrominated diphenyl ethers occurrence in major inflowing rivers of Lake Chaohu (China): characteristics, potential sources and inputs to lake.
Chemosphere
PUBLISHED: 08-07-2013
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Eight commonly occurring polybrominated diphenyl ethers (PBDEs), including BDE 28, 47, 99, 100, 153, 154, 183, 207, and 209, were investigated in water samples from seven major inflowing rivers of Lake Chaohu to determine the distribution characteristics, potential sources and inputs to the lake. The sum of 8 BDE congeners (?8PBDEs) had a concentration varied from 0.31 to 84 ng L(-1), with those of BDE 209, BDE 47, BDE 99, and BDE 153 being 0.31-83, <0.012-0.36, <0.012-1.3, and <0.012-0.77 ng L(-1), respectively. These levels were in the high range of the global PBDEs concentrations in the water environments. The highest concentrations of ?8PBDEs were detected in the western rivers, of which the main pollution sources were strongly related to human activities in urban centers, such as automobile-derived wastes. A sewage treatment plant was likely an important source of the lower brominated BDEs input to one western river. The correlation analyses (all p<0.05) between PBDEs and DOC, TN, TP, and EC, suggested that the distributions and sources of PBDEs in rivers might also be related with the soil erosion by heave floods. ?8PBDEs input to Lake Chaohu from the rivers outlets was estimated at 344 kg yr(-1) during the flood season. BDE 209 was the dominant contributor with an input of 340 kg yr(-1), followed by BDE 99 (1.3 kg yr(-1)), BDE 47 (0.83 kg yr(-1)) and BDE 153 (0.60 kg yr(-1)).
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The elbow flex-ex: a new sign to detect unilateral upper extremity non-organic paresis.
J. Neurol. Neurosurg. Psychiatr.
PUBLISHED: 05-21-2013
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OBJECTIVE: To examine a new neurological sign that uses synergistic oppositional movements of the arms to evaluate for non-organic upper extremity weakness. METHODS: Patients with unilateral arm weakness were tested in a standing or sitting position with the elbows flexed at 30°. The examiner held both forearms near the wrists while asking the patient to flex or extend the normal arm at the elbow and simultaneously feeling for flexion or extension of the contralateral (paretic) arm. In patients with organic paresis, there was not a significant detectable force of contralateral opposition of the paretic limb. Patients with non-organic arm weakness had detectable strength of contralateral opposition in the paretic arm when the normal arm was tested. RESULTS: The test was first performed on 23 patients with no complaint of arm weakness. Then, 31 patients with unilateral arm weakness were tested (10 with non-organic weakness and 21 with organic weakness). The elbow flex-ex sign correctly identified the cause of weakness in all cases. CONCLUSIONS: The elbow flex-ex sign is useful in differentiating between functional and organic arm paresis.
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Quantum chemical and direct dynamic study on homogeneous gas-phase formation of PBDD/Fs from 2,4,5-tribromophenol and 3,4-dibromophenol.
Chemosphere
PUBLISHED: 05-15-2013
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2,4,5-Tribromophenol (2,4,5-TBP) and 3,4-dibromophenol (3,4-DBP) have the minimum number of Br atoms needed to form 2,3,7,8-PBDD/Fs, which are the most toxic among all 210 PBDD/F isomers. A mechanistic understanding of the formation of PBDD/Fs is a prerequisite for minimizing their emissions. In this paper, the homogeneous gas-phase formation of PBDD/Fs from 2,4,5-TBP and 3,4-DBP as precursors was investigated theoretically by using the density functional theory (DFT) method. The mathematical model to predict the formation of PBDD/Fs places a high demand on accurate kinetic parameters. So, the rate constants of key elementary steps involved in the formation of PBDD/Fs were calculated by using canonical variational transition-state (CVT) theory with small curvature tunneling (SCT) contribution over a wide temperature range of 600-1200K. The pre-exponential factors and the activation energies are also reported. This might be the first to investigate the formation of 2,3,7,8-PBDD/Fs. The present study shows that the formation of PBDDs dominates over the formation of PBDFs. The meta bromine facilitates the dimerization of bromophenoxy radicals (BPRs), whereas the para and ortho bromines suppress the dimerization of BPRs.
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A new fluorescence "off-on" chemodosimeter for L-cysteine based on water-soluble polythiophene.
Talanta
PUBLISHED: 04-05-2013
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A novel water-soluble cationic conjugated polymer, denoted as poly 2,5-[3-(1,1-dimethyl-4-piperidine methylene)thiophene] chloride?PDPMT-Cl was a novel fluorescent material. Fluorescence can be quenched by [AuCl4](-) effectively. On addition of l-cysteine (l-Cys) in [AuCl4](-)-PDPMT-Cl, fluorescence recovered. A new method to detect l-Cys was established successfully by designing a fluorescent "off-on" probe. The method showed good sensitivity and selectivity. Under optimized condition, the fluorescence intensity was linear to l-Cys concentration varying from 1.0 × 10(-8)M to 6.0 × 10(-5)M (?=0.9982). The detection limit (3?) was 1.39 × 10(-10)M. The method was successfully used for the determination of l-Cys in human serum and compound amino acid injection.
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Theoretical investigation on the mechanisms and kinetics of OH-initiated photooxidation of dimethyl phthalate (DMP) in atmosphere.
Chemosphere
PUBLISHED: 03-27-2013
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The atmospheric OH-initiated degradation mechanisms of dimethy phthalate (DMP) are analyzed at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. The principal products detected experimentally are confirmed by this study while several major intermediates are reported for the first time. Additionally, the pathway scheme of hydroxylation reaction of DMP is proposed. The results about initial steps indicate that hydroxyl radical is most likely to be added to the ortho-carbon atom among additional reactions, while H atoms in methyl group are the most favorable to be abstracted by the OH radical. The rate constants of the elementary reactions over the temperature of 200-400 K were deduced using RRKM theory. The overall rate constant of the title reaction is 1.18×10(-12) cm(3) molecule(-1) s(-1) at 298 K and 760 Torr while H abstraction reactions predominate. According to the rate constants given at different temperatures, the Arrhenius equation is fitted. The atmospheric half life of DMP with respect to OH is estimated to be 6.8 days.
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Water-soluble fluorescent probes based on dendronized polyfluorenes for cell imaging.
Macromol Rapid Commun
PUBLISHED: 01-06-2013
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Novel water-soluble dendronized fluorescent polyfluorenes (DFPFs) are prepared from hydrophilic monomers and hydrophobic comonomers. Incomplete energy transfer is found to result in a two-color emission of the DFPFs at around 410 and 650 nm. The incomplete energy transfer can be attributed to the poor compatibility between the fluorene and benzothiadiazole units. Polyethylene oxide (PEO) encapsulation of the DFPFs shows over 90% cell viability, indicating good biocompatibility. These DFPFs show differential cellular uptake. P1 with fewer PEO chains exhibits limited cellular membrane uptake and low brightness in cells. By contrast, P3 with more PEO chains is efficiently internalized by cells and accumulated in the cytoplasm. A strong fluorescence from whole cells is also observed.
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Formation of bromophenoxy radicals from complete series reactions of bromophenols with H and OH radicals.
Chemosphere
PUBLISHED: 01-03-2013
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The bromophenoxy radicals (BPRs) are key intermediate species involved in the formation of polybrominated dibenzo-p-dioxin/dibenzofurans (PBDD/Fs). In this work, the formation of BPRs from the complete series reactions of 19 bromophenol (BP) congeners with H and OH radicals were investigated theoretically by using the density functional theory (DFT) method and the direct dynamics method. The geometries and frequencies of the reactants, transition states, and products were calculated at the MPWB1K/6-31+G(d,p) level, and the energetic parameters were further refined by the MPWB1K/6-311+G(3df,2p) method. The rate constants were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) contribution over a wide temperature range of 600-1200K. The present study indicates that the reactivity of the O-H bonds in BPs as well as the formation potential of BPRs from BPs is strongly related to the bromine substitution pattern. The obtained results can be used for future estimates of PBDD/F emissions quantity based on the well estimated PCDD/F inventory.
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A 100 year sedimentary record of heavy metal pollution in a shallow eutrophic lake, Lake Chaohu, China.
J Environ Monit
PUBLISHED: 09-13-2011
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This study has worked on the evaluation of the temporal and spatial evolution of heavy metal contamination in sediment taken from a shallow eutrophic lake, Lake Chaohu, China, over the last 100 years, and thereby used (137)Cs and (210)Pb dating, a PIRLA procedure, statistical analysis, geochemical normalization and a enrichment factor calculation (EF). Concentrations of 5174, 29?325, 10.7, 36.4, 20.4, 386.0, 21.1 and 38.4 mg kg(-1) for Ti, Fe, Co, Cr, Cu, Mn, Pb and Zn, respectively, are proposed as natural background values for the Lake Chaohu based on a PIRLA procedure. The contamination history from the last 100 years can be divided into two periods. Before the 1960s, heavy metal contamination did not occur and there was no spatial difference for heavy metal distribution. Since the 1960s, heavy metal enrichment and contamination has occurred, and the west half of the lake region showed a higher degree of contamination than the east half to various intensified anthropogenic activities. In the east half of the lake region, the anthropogenic source of heavy metals mainly originated from agricultural intensification, whereas in the west half of the lake it originated from city runoff and industry as well as agriculture. In all anthropogenic heavy metals, Co is only from industry.
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Therapeutic effects of neuregulin-1 in diabetic cardiomyopathy rats.
Cardiovasc Diabetol
PUBLISHED: 07-12-2011
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Diabetic cardiomyopathy (DCM) is a disorder of the heart muscle in people with diabetes, which is characterized by both systolic and diastolic dysfunction. The effective treatment strategy for DCM has not been developed.
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Medical image registration using fuzzy theory.
Comput Methods Biomech Biomed Engin
PUBLISHED: 05-24-2011
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Mutual information (MI)-based registration, which uses MI as the similarity measure, is a representative method in medical image registration. It has an excellent robustness and accuracy, but with the disadvantages of a large amount of calculation and a long processing time. In this paper, by computing the medical image moments, the centroid is acquired. By applying fuzzy c-means clustering, the coordinates of the medical image are divided into two clusters to fit a straight line, and the rotation angles of the reference and floating images are computed, respectively. Thereby, the initial values for registering the images are determined. When searching the optimal geometric transformation parameters, we put forward the two new concepts of fuzzy distance and fuzzy signal-to-noise ratio (FSNR), and we select FSNR as the similarity measure between the reference and floating images. In the experiments, the Simplex method is chosen as multi-parameter optimisation. The experimental results show that this proposed method has a simple implementation, a low computational cost, a fast registration and good registration accuracy. Moreover, it can effectively avoid trapping into the local optima. It is adapted to both mono-modality and multi-modality image registrations.
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The physico-chemical characterization of casein-modified surfaces and their influence on the adhesion of spores from a Geobacillus species.
Biofouling
PUBLISHED: 05-21-2011
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To gain a better understanding of the factors influencing spore adhesion in dairy manufacturing plants, casein-modified glass surfaces were prepared and characterized and their effect on the adhesion kinetics of spores from a Geobacillus sp., isolated from a dairy manufacturing plant (DMP) was assessed using a flow chamber. Surfaces were produced by initially silanizing glass using (3-glycidyloxypropyl) trimethoxysilane (GPS) or (3-aminopropyl) triethoxysilane to form epoxy-functionalized (G-GPS) or amino-functionalized glass (G-NH(2)) substrata. Casein was grafted to the G-GPS directly by its primary amino groups (G-GPS-casein) or to G-NH(2) by employing glutaraldehyde as a linking agent (G-NH(2)-glutar-casein). The surfaces were characterised using streaming potential measurements, contact angle goniometry, infrared spectroscopy and scanning electron microscopy. The attachment rate of spores suspended in 0.1 M KCl at pH 6.8, was highest on the positively charged (+14 mV) G-NH(2) surface (333 spores cm(-2) s(-1)) compared to the negatively charged glass (-22 mV), G-GPS (-20 mV) or G-GPS-casein (-21 mV) surfaces (162, 17 or 6 spores cm(-2) s(-1) respectively). Whilst there was a clear decrease in attachment rate to negatively charged casein-modified surfaces compared to the positively charged amine surface, there was no clear relationship between surface hydrophobicity and spore attachment rate.
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Phosphorus fractionation in different trophic sediments of lakes from different regions, China.
J Environ Monit
PUBLISHED: 02-25-2011
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The characteristics of organic phosphorus (P(o)) fractions in the sediments of nine lakes from the middle and lower reaches of the Yangtze River region, Yungui Plateau, Qinghai-Tibet Plateau, Northeast China Region, and Mongolia-Xinjiang Plateau, China were investigated and the differences of the different lakes on P fractionation was discussed. The results indicated that organic matter (OM) showed significant positive correlations with P(o) in sediment samples, and the rank order of the P(o) fractions was: residual P(o) > HCl-P(o) > fulvic acid-P(o) > humic acid-P(o) > NaHCO(3)-P(o) with mean relative proportions 7.4 : 3.4 : 2.4 : 1.7 : 1.0. The labile and moderately labile P(o) were the main fractions in the sediments for shallow eutrophic lakes except for Lake Qilu, however, nonlabile P(o) was dominant in the sediments from deep lakes. Labile P(o) was significantly correlated with total phosphorus (TP), inorganic phosphorus (P(i)), P(o), NaHCO(3)-P(i), HCl-P(i) and NaOH-P(i), and the nonlabile P(o) was significantly and positively related to OM, TP, P(o) and NaOH-P(i).
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Mechanism and direct kinetics study on the homogeneous gas-phase formation of PBDD/Fs from 2-BP, 2,4-DBP, and 2,4,6-TBP as precursors.
Environ. Sci. Technol.
PUBLISHED: 02-10-2011
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This study investigated the homogeneous gas-phase formation of polybrominated dibenzo-p-dioxin/dibenzofurans (PBDD/Fs) from 2-BP, 2,4-DBP, and 2,4,6-TBP as precursors. First, density functional theory (DFT) calculations were carried out for the formation mechanism. The geometries and frequencies of the stationary points were calculated at the MPWB1K/6-31+G(d,p) level, and the energetic parameters were further refined by the MPWB1K/6-311+G(3df,2p) method. Then, the formation mechanism of PBDD/Fs was compared and contrasted with the PCDD/F formation mechanism from 2-CP, 2,4-DCP, and 2,4,6-TCP as precursors. Finally, the rate constants of the crucial elementary reactions were evaluated by the canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) correction over a wide temperature range of 600-1200 K. Present results indicate that only BPs with bromine at the ortho position are capable of forming PBDDs. The study, together with works already published from our group, clearly shows an increased propensity for the dioxin formations from BPs over the analogous CPs. Multibromine substitutions suppress the PBDD/F formations.
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A sensitive enzymatic method for paraoxon detection based on enzyme inhibition and fluorescence quenching.
Talanta
PUBLISHED: 01-06-2011
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A sensitive and selective method for the paraoxon detection based on enzyme inhibition and fluorescence quenching was presented in this study. Under the catalytic effect of acetylcholinesterase (AChE), acetylthiocholine (ATCh) hydrolysis released thiocholine (TCh) which could react with N-(7-dimethylamino-4-methylcoumarin-3-yl) maleimide (DACM) to produce a blue fluorescence compound. Subsequently, AChE catalytic activity was inhibited with the addition of paraoxon, which caused TCh decreased, leading to a significant decrease of the blue fluorescent compound. Meanwhile, p-nitrophenol, the hydrolysis product of paraoxon, would lead to a quenching of the fluorescence. Therefore, fluorescence intensity of the system would decrease dramatically by a combined effect of enzyme inhibition and fluorescence quenching. Under optimal experimental conditions, an excellent linear relationship between the decrease of fluorescence intensity and paraoxon concentration over the range from 5.5 × 10(-12) to 1.8 × 10(-10) mol L(-1) was obtained. Fluorescence background caused by nonenzymatic hydrolysis of ATCh or other matters was relatively low, the proposed approach offered adequate sensitivity for the detection of paraoxon at 3.5 × 10(-12) mol L(-1).
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Interleukin-11 reduces TLR4-induced colitis in TLR2-deficient mice and restores intestinal STAT3 signaling.
Gastroenterology
PUBLISHED: 05-17-2010
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The roles of intestinal Toll-like receptors (TLR) in the pathogenesis of colitis are not known. TLR2 and TLR4 appear to protect against dextran sodium sulfate-induced colitis by promoting mucosal integrity, but it is not clear whether this method of protection occurs in other models of colitis. We investigated the roles of TLR2 and TLR4 and the cell types that express these receptors during infectious colitis.
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Platycodon grandiflorum induces apoptosis in SKOV3 human ovarian cancer cells through mitochondrial-dependent pathway.
Am. J. Chin. Med.
PUBLISHED: 04-14-2010
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Platycodon grandiflorum (Jacq.) A. DC., a Chinese food and medicine, has been used as expectorant traditionally. The present study aimed to investigate the effect of Platycodon grandiflorum extract (PGE) on SKOV3 ovarian cancer cells. 3-(4,5- dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay was used to monitor cell numbers, Annexin-V/propidium iodide (PI) staining, RT-PCR and Western blot were used to examine cell apoptosis, caspases activation. Bcl-2 and Bax expressions and mitochondrial cytochrome c release. Our result showed that PGE-induced apoptosis was associated with activation of caspase-3, -8 and -9, down-regulation of Bcl-2, up-regulation of Bax and release of mitochondrial cytochrome c to cytosol. The data indicate that PGE may have anti-tumor effect mainly via caspase-3 and caspase-9 dependent apoptotic pathway.
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Emotional stress as a trigger of myasthenic crisis and concomitant takotsubo cardiomyopathy: a case report.
J Med Case Rep
PUBLISHED: 03-06-2010
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Myasthenia gravis is a neuromuscular junction post-synaptic autoimmune disorder. Myasthenic crisis is characterized by respiratory failure requiring mechanical ventilation. Takotsubo cardiomyopathy is a rare clinical syndrome defined as a profound but reversible left ventricular dysfunction in the absence of coronary artery disease.
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Lack of significant association between TGF-?1-590C/T polymorphism and breast cancer risk: a meta-analysis.
Med. Oncol.
PUBLISHED: 02-22-2010
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Transforming growth factor ?1 (TGF-?1) is a cytokine that plays an important role in the control of cell proliferation and differentiation in breast cancer. The -509C/T polymorphism in the TGF-?1 gene has been implicated in breast cancer risk. However, studies on the association between this polymorphism and breast cancer risk have produced conflicting results. To derive a more precise estimation of the relationship, a meta-analysis of the -509C/T polymorphism (5,825 cases and 7,953 controls) from seven published case-control studies was performed. Our analysis suggests that -509C/T has no association with breast cancer risk when using either dominant [odds ratio (OR) = 1.01, 95% confidence intervals (CI): 0.82-1.24], or recessive models (OR = 0.91, 95% CI: 0.66-1.27), or other genetic models to analyze the data. In ethnic subgroups analysis, -509C/T also did not appear to be a risk factor for breast cancer. However, larger scale primary studies are still required to further evaluate the interaction of TGF-?1 -509C/T polymorphism and breast cancer risk in specific populations.
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TGF-?1 29T/C polymorphism and breast cancer risk: a meta-analysis involving 25,996 subjects.
Breast Cancer Res. Treat.
PUBLISHED: 02-04-2010
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Transforming growth factor ?1 (TGF-?1) is a cytokine, playing an important role in controlling cell proliferation and differentiation involved in breast cancer. It was reported the 29T/C polymorphism in TGF-?1 has been implicated in breast cancer risk. However, studies on the association between this polymorphism and breast cancer remain conflicting. To derive a more precise estimation of the relationship, a meta-analysis of 10,341 cases and 15,655 controls from fifty published case-control studies was performed. Our analysis suggested that 29T/C has no association with a trend of breast cancer risk when using both dominant [odds ratio (OR) = 1.01, 95% confidence intervals (CI) 0.96-1.07] and recessive models (OR = 0.98, 95% CI 0.89-1.08) to analyze the data. In ethnic subgroups analysis, 29T/C also did not appear to be risk factors for breast cancer. However, larger scale primary studies are required to further evaluate the interaction of TGF-?1 29T/C polymorphism and breast cancer risk in specific populations.
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The single IgG IL-1-related receptor controls TLR responses in differentiated human intestinal epithelial cells.
J. Immunol.
PUBLISHED: 02-03-2010
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Intestinal epithelial cells (IECs) are constantly exposed to enteric microbes. Although IECs express TLRs that recognize bacterial products, the activation of these TLRs is strictly controlled through poorly understood mechanisms, producing a state of hyporesponsiveness and preventing unwanted inflammation. The single IgG IL-1-related receptor (Sigirr) is a negative regulator of TLRs that is expressed by IECs and was recently shown to inhibit experimental colitis. However, the importance of Sigirr in IEC hyporesponsiveness and its distribution within the human colon is unknown. In this study, we investigated the role of Sigirr in regulating epithelial-specific TLR responses and characterized its expression in colonic biopsy specimens. Transformed and nontransformed human IECs were cultured as monolayers. Transient gene silencing and stable overexpression of Sigirr was performed to assess innate IEC responses. Sigirr expression in human colonic biopsy specimens was examined by immunohistochemistry. Bacterial infection of IECs and exposure to flagellin transiently decreased Sigirr protein expression, concurrent with secretion of the neutrophil chemokine IL-8. Sigirr gene silencing augmented chemokine responses to bacterial flagellin, Pam3Cys, and the cytokine IL-1beta. Conversely, stable overexpression of Sigirr diminished NF-kappaB-mediated IL-8 responses to TLR ligands. We also found that Sigirr expression increased as IECs differentiated in culture. This observation was confirmed in biopsy sections, in which Sigirr expression within colonic crypts was prominent in IECs at the apex and diminished at the base. Our findings show that Sigirr broadly regulates innate responses in differentiated human IECs; therefore, it may modulate epithelial involvement in infectious and inflammatory bowel diseases.
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A computerized system for detecting signals due to drug-drug interactions in spontaneous reporting systems.
Br J Clin Pharmacol
PUBLISHED: 01-19-2010
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WHAT IS ALREADY KNOWN ABOUT THE SUBJECT: * Concomitant use of different drugs may yield excessive risk for adverse drug reactions and it is a challenging task to do surveillance on the safety profile of the interaction between different drugs. * Currently, several methods are used by pharmacoepidemiologists and statisticians to detect possible drug-drug interactions in spontaneous reporting systems. * However, with the increasing number of reports in the system, there is a growing need for a computerized system that could facilitate the process of data arrangement and detection of drug interaction.
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[Feature detection of tissue lesion in HIFU based on SOM].
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi
PUBLISHED: 10-10-2009
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Noninvasive detection of tissue lesion is an important aided way in the process of high intensity focused ultrasound (HIFU) treatment. A new method is proposed for noninvasive detection of tissue lesion based on self-organizing maps (SOM) network. Tissue lesion, created by HIFU exposures, inevitably leads to change in B-mode image, since some new interfaces will appear in tissue. The difference-sub-image near focus of HIFU, where the tissue lesion appears, is used. Feature of lesion in difference-sub-image is extracted using the method based on SOM network. Experimental results show that the performance of the method proposed in this paper is better than that of others, such as the methods based on average gray, energy and standard deviation of difference-sub-image.
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[Dosimetric verification and clinical efficacy of intensity modulated radiotherapy in nasopharyngeal carcinoma].
Zhong Nan Da Xue Xue Bao Yi Xue Ban
PUBLISHED: 09-26-2009
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To investigate dosimetric characteristics and to evaluate the clinical efficacy of intensity modulated radiotherapy (IMRT) as compared with conventional radiotherapy in nasopharyngeal carcinoma (NPC).
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Ginseng leaf-stem: bioactive constituents and pharmacological functions.
Chin Med
PUBLISHED: 04-30-2009
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Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginsengs leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. Ginseng leaf-stem extract contains numerous active ingredients, such as ginsenosides, polysaccharides, triterpenoids, flavonoids, volatile oils, polyacetylenic alcohols, peptides, amino acids and fatty acids. The extract contains larger amounts of the same active ingredients than the root. These active ingredients produce multifaceted pharmacological effects on the central nervous system, as well as on the cardiovascular, reproductive and metabolic systems. Ginseng leaf-stem extract also has anti-fatigue, anti-hyperglycemic, anti-obesity, anti-cancer, anti-oxidant and anti-aging properties. In normal use, ginseng leaf-stem extract is quite safe; adverse effects occur only when it is over dosed or is of poor quality. Extracts from ginseng root and leaf-stem have similar multifaceted pharmacological activities (for example central nervous and cardiovascular systems). In terms of costs and source availability, however, ginseng leaf-stem has advantages over its root. Further research will facilitate a wider use of ginseng leaf-stem.
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Therapeutic effects of neuregulin-1 gene transduction in rats with myocardial infarction.
Coron. Artery Dis.
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In this study, we investigated whether lentivirus-mediated gene transduction improves the cardiac function in rats with myocardial infarction and the mechanisms involved.
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A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai, China.
J Environ Sci (China)
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Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (Po), inorganic phosphorus (Pi) and organic carbon and nitrogen stable isotopes (delta13Corg and delta15N) in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of delta13Corg and delta15N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.
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Ginsenoside Re: Its chemistry, metabolism and pharmacokinetics.
Chin Med
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Ginsenosides, the bioactive components of ginseng, can be divided into two major groups, namely 20(S)-protopanaxatriol (e.g. Re, Rg1, Rg2, and Rb3) and 20(S)-protopanaxadiol (e.g. Rb1, Rb2, Rc, and Rd). Biological and environmental factors may affect the content of ginsenosides in different parts of ginseng plant. Evidence from pharmacokinetic and metabolic studies of Re demonstrated that (1) the absorption of Re is fast in gastrointestinal tract; (2) Re may be metabolized mainly to Rh1 and F1 by intestinal microflora before absorption into blood; and (3) Re is quickly cleared from the body.
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Mechanism and kinetics study on the OH-initiated oxidation of organophosphorus pesticide trichlorfon in atmosphere.
Sci. Total Environ.
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Trichlorfon [O,O-dimethyl-(2,2,2-trichloro-1-hydroxy-ethyl) phosphonate] (TCF) is a kind of widely used organophosphorus pesticides. In this paper, the mechanism and possible oxidation products for the OH-initiated reactions of TCF are studied at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The study shows that H abstraction reaction from the CH(3) group and the CH group as well as OH addition reaction to the P atom are energetically favorable for the reactions of TCF and the main products are (CH(3)O)(2)POOH (P1), CCl(3)CHOHPOOH(OCH(3)) (P2), CH(3)OPO(2) (P3), CCl(3)COPO(OCH(3))(2) (P6) and HCHO. On the basis of the quantum chemical information, the kinetic calculation is performed and the rate constants are calculated over a temperature range of 200-800K using the transition state theory and canonical variational transition state theory with small-curvature tunneling effect. The Arrhenius formulas of rate constants with the temperature are fitted and the lifetimes of the reaction species in the troposphere are estimated according to the rate constants, which can provide helpful information for the model simulation study.
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A 100-year sedimentary record of natural and anthropogenic impacts on a shallow eutrophic lake, Lake Chaohu, China.
J Environ Monit
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In this study, the sediment profiles of total organic carbon, total nitrogen, C/N ratios, total phosphorus, N/P ratios, C/P ratios, particle sizes, and stable carbon and nitrogen isotopes (?(13)C and ?(15)N) were used to investigate natural and anthropogenic impacts on Lake Chaohu over the past 100 years. Before 1960, Lake Chaohu experienced low productivity and a relatively steady and low nutrient input. The increasing concentration and fluxes of total organic carbon, total nitrogen, total phosphorus, together with changes in the ?(13)C and ?(15)N of organic material in the sediment cores, suggested that the anthropogenic effects on trophic status first started because of an increase in nutrient input caused by a population increase in the drainage area. With the construction of the Chaohu Dam, an increase in the utilization of fertilizer and the population growth which occurred since 1960, stable depositional conditions and increasing nutrient input resulted in a dominantly algae-derived organic matter source and high productivity. Nutrient input increased most significantly around 1980 following the rapidly growing population, with concomitant urbanization, industrial and agricultural development. This study also revealed that the concentration and distribution of nutrients varied between different areas of sediment within Lake Chaohu because of the influence of different drainage basins and pollution sources.
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