In JoVE (1)
Other Publications (10)
- Langmuir : the ACS Journal of Surfaces and Colloids
- Colloids and Surfaces. B, Biointerfaces
- Advances in Biochemical Engineering/biotechnology
- Research in Microbiology
- Fungal Genetics and Biology : FG & B
- The European Physical Journal. E, Soft Matter
- Journal of Biotechnology
- Chemical Society Reviews
- Journal of Colloid and Interface Science
Articles by Arno Kwade in JoVE
진공 조건에서 반발 계수의 측정을위한 실험 장치 개발 Sven Drücker1, Isabell Krautstrunk2, Maria Paulick2, Khashayar Saleh1, Martin Morgeneyer1, Arno Kwade2 1Industrial Process Engineering, University of Technology of Compiègne, 2Institute for Particle Technology, Technische Universität Braunschweig 반발 계수는 충돌시에 운동 에너지의 손실을 설명하는 매개 변수이다. 여기서, 진공 조건에서 자유 낙하 설치 높은 충격 속도와 마이크로 미터 범위의 입자 반발 파라미터의 계수를 결정할 수 있도록 개발되고있다.
Other articles by Arno Kwade on PubMed
Determination of Adhesion Between Single Aspergillus Niger Spores in Aqueous Solutions Using an Atomic Force Microscope Langmuir : the ACS Journal of Surfaces and Colloids. Jul, 2010 | Pubmed ID: 20387816 The interaction force between single cells in contact is of high interest in various interdisciplinary fields of biotechnology, for instance, in cultivation or biofilm formation. A method for the determination of adhesion forces between two single Aspergillus niger spores in different aqueous solutions was established in this study. Adhesion force distributions were determined at three different sodium chloride concentrations and two different pH values using an atomic force microscope (AFM). It was pointed out that adhesion data can be described by log-normal density functions, of which corresponding parameters have been estimated. Using the knowledge of distribution shape, the influence of the environmental condition on the mean values of adhesion force could be studied quantitatively. The highest value of 0.95 nN was observed at pH 2.5 and an ionic strength of 0.5 mol L(-1). Decreasing the ionic strength to 0.05 mol L(-1) decreases the adhesion force mean for about 25%. Increasing the pH value to pH 5 at a sodium chloride concentration of 0.154 mol L(-1) entails a decrease of adhesion from 0.88 to 0.56 nN. These results qualitatively agree with the absolute value of the expected surface potential of Aspergillus niger spores, which is much higher at pH 5 and should take more effect at lower concentrations of counterions.
Atomic Force Microscopy Studies on the Nanomechanical Properties of Saccharomyces Cerevisiae Colloids and Surfaces. B, Biointerfaces. Aug, 2010 | Pubmed ID: 20452756 In the past years atomic force microscopy (AFM) techniques have turned out to be a suitable and versatile tool for probing the physical properties of microbial cell surfaces. Besides interaction forces, nanomechanical properties can be obtained from force spectroscopic measurements. Analyzing the recorded force curves by applying appropriate models allows the extraction of cell mechanical parameters, e.g. the Young's modulus or the cellular spring constant. In the present work the nanomechanical properties of the baker's yeast Saccharomyces cerevisiae are extensively studied by force spectroscopy using an AFM. Single cells deform purely elastically so that a cellular spring constant can reliably be determined. It is presented, how this spring constant depends on the probing position on the cell, and how it depends on the extracellular osmotic conditions. Investigations aiming a statistically firm description of the nanomechanical behavior of the yeast cell population are conducted. Finally, the informative value of the cellular spring constant as a cell mechanical parameter is critically discussed.
Filamentous 곰 팡이의 형태: 세포 생물학 프로세스 엔지니어링을 사용 하 여 누 니제르에 연결 합니다 Advances in Biochemical Engineering/biotechnology. 2010 | Pubmed ID: 20490972 다양 한 바이오 프로세스에서 filamentous 곰 팡이, 예를 들면 누 니제르, 그들의 분 비 효율으로 인해 고부가가치 제품의 생산에 대 한 광범위 하 게 적용 됩니다. 그러나, 이러한 미생물, 전송 현상과 관련된 생산성의 형태 사이의 얽힌된 관계입니다. 형태학 특성 자유롭게 분산 된 사체 및 집계 된 바이오 매스의 뚜렷한 펠 릿에 따라 다릅니다. 따라서, mycel 또는 펠 렛 재배에 대 한 장단점 밖으로 균형을 신중 하 게 해야 합니다. Morphogenesis filamentous 미생물의이 불 충 분 한 이해, 동일한 품질의 inocula의 재현성 함께 곰 팡이 형태 종종 산업 생산에서 생산성의 병목은. 생산의 최적화를 과정 그것은 이러한 미생물 생물 공학 및 입자 기술에 접근의 분자 및 세포 생물학의 더 나은 이해를 얻기 위해 매우 중요 특히 characterise 성장 조건 간의 상호 작용을 세포 형태, 포자 균 상호 작용 및 제품 형성. 입자 및 이미지 분석 기법으로 micromechanical 장치에 발전과 응용 프로그램을 곰 팡이 지켜온 filamentous 셀에 사용할 수 있는 양적 형태학 데이터를 만들었습니다. 이 장에서 동작, 컨트롤 및 형태, 전송 그라디언트 filamentous 곰 팡이의 물질 대사를 이해 접근법의 특성 분석에 국한의이 라인의 야심찬 측면. 이러한 데이터를 바탕으로, 유전자 제품의 복잡 한 생산 경로 내에서 A. 니제르 morphogenesis의 병목 상태를 식별 하 고이 생산 수율을 향상 시킬 수 있습니다.
On the Origin of the Electrostatic Surface Potential of Aspergillus Niger Spores in Acidic Environments Research in Microbiology. Dec, 2011 | Pubmed ID: 21835241 The electrostatic surface potential of fungal spores is generally regarded as potentially influencing spore aggregation and pellet formation in submerged cultures of filamentous fungi. Spores of Aspergillus niger are typically characterized by negative zeta potentials over a wide range of pH values. In this study, this particular behavior is ascribed to the presence of an extensive melanin coating. It is proposed on the basis of zeta potential and pigment extraction experiments that this outermost layer affects the pH-dependent surface potential in two manners: (i) by the addition of negative charges to the spore surface and (ii) by the pH-dependent release of melanin pigment. Chemical analyses revealed that deprotonation of melanin-bound carboxyl groups is most probably responsible for pigment release under acidic conditions. These findings were incorporated into a simple model which has the ability to qualitatively explain the results of zeta potential experiments and, moreover, to provide the basis for quantitative investigations on the role of electrostatics in spore aggregation.
초기 포자 접착 누 니제르에서 펠 릿 및 Biofilm 형성에의 역할 Fungal Genetics and Biology : FG & B. Jan, 2012 | Pubmed ID: 22178638 다양 한 유기 및 무기 재료에 곰 팡이 성장. 식민지 설립 및 고체 표면에 성장 셀 포자 또는 균 사이 상호 작용은 펠 릿 또는 biofilms 같은 3 차원 사체 구조 개발을 위한 전제 조건 포자와 균 기판에의 접착 력이 필요 합니다. 표면 밀착 ungerminated conidia 뒤에 추가 접착 력을 형성 세균 튜브 및 성장 하 고 있는 균의 초기 부착으로 이루어진 2 단계 과정으로 설명 하고있다. 현재의 연구에서 우리는 펠 렛을 ungerminated 포자와 Aspergillus 니제르에서 biofilm 형성의 접착의 기여를 분석 했다. 멜 라 닌 생 합성 결핍 돌연변이 polyketide synthase 색소의 생 합성에 필수적인 인코딩 alb1 유전자의 삭제에 의해 건설 되었다. Δalb1 conidia 변경 된 표면 구조 및 물리 화학적 표면 속성 변경. 액체 문화 포자 표면 첨부 파일에 집계 포자 pH 의존 방식에서 야생 종류와 돌연변이 사이 다. 액체 문화 더 펠 렛에 형성 세균 튜브 및 hyphal 준수 포자 첨부 파일의 초기 단계에서 결함에 대 한 보상 수 있습니다 나타내는 변경 된 스 포어 스 포어 상호 작용에 의해 영향을 받지 않습니다. 대조적으로, Δalb1 conidia 폴리머 표면에 접착을 홍보 하는 조건 하에서 돌연변이 형태 보다 안정적인 biofilms 초기 포자 접착 착 성장을 지원 제안 야생 타입 보다.
Colloidal Aggregates Tested Via Nanoindentation and Quasi-simultaneous 3D Imaging The European Physical Journal. E, Soft Matter. Nov, 2012 | Pubmed ID: 23183925 The mechanical properties of aggregated colloids depend on the mutual interplay of inter-particle potentials, contact forces, aggregate structure and material properties of the bare particles. Owing to this variety of influences, experimental results from macroscopic mechanical testings were mostly compared to time-consuming, microscopic simulations rather than to analytical theories. The aim of the present paper was to relate both macroscopic and microscopic mechanical data with each other and simple analytical models. We investigated dense amorphous aggregates made from monodisperse poly-methyl methacrylate (PMMA) particles (diameter: 1.6 μm via nanoindentation in combination with confocal microscopy. The resulting macroscopic information was complemented by the three-dimensional aggregate structure as well as the microscopic strain field and strain tensor. The measured strain field and tensor were in reasonable agreement with the predictions from analytical continuum theories. Consequently, the measured force-depth curves could be analyzed within a theoretical framework that had been frequently used for nanoindentation of atomic matter such as metals, ceramics and polymers. The extracted values for hardness and effective Young's modulus represented average values characteristic of the aggregate. On the basis of of these parameters we discuss the influence of the strength of particle bonds by introducing polystyrene (PS) between the particles.
Characterization and Control of Fungal Morphology for Improved Production Performance in Biotechnology Journal of Biotechnology. Jan, 2013 | Pubmed ID: 22771505 Filamentous fungi have been widely applied in industrial biotechnology for many decades. In submerged culture processes, they typically exhibit a complex morphological life cycle that is related to production performance--a link that is of high interest for process optimization. The fungal forms can vary from dense spherical pellets to viscous mycelia. The resulting morphology has been shown to be influenced strongly by process parameters, including power input through stirring and aeration, mass transfer characteristics, pH value, osmolality and the presence of solid micro-particles. The surface properties of fungal spores and hyphae also play a role. Due to their high industrial relevance, the past years have seen a substantial development of tools and techniques to characterize the growth of fungi and obtain quantitative estimates on their morphological properties. Based on the novel insights available from such studies, more recent studies have been aimed at the precise control of morphology, i.e., morphology engineering, to produce superior bio-processes with filamentous fungi.
Process Engineering with Planetary Ball Mills Chemical Society Reviews. Sep, 2013 | Pubmed ID: 23389051 Planetary ball mills are well known and used for particle size reduction on laboratory and pilot scales for decades while during the last few years the application of planetary ball mills has extended to mechanochemical approaches. Processes inside planetary ball mills are complex and strongly depend on the processed material and synthesis and, thus, the optimum milling conditions have to be assessed for each individual system. The present review focuses on the insight into several parameters like properties of grinding balls, the filling ratio or revolution speed. It gives examples of the aspects of grinding and illustrates some general guidelines to follow for modelling processes in planetary ball mills in terms of refinement, synthesis' yield and contamination from wear. The amount of energy transferred from the milling tools to the powder is significant and hardly measurable for processes in planetary ball mills. Thus numerical simulations based on a discrete-element-method are used to describe the energy transfer to give an adequate description of the process by correlation with experiments. The simulations illustrate the effect of the geometry of planetary ball mills on the energy entry. In addition the imaging of motion patterns inside a planetary ball mill from simulations and video recordings is shown.
Linking Aggregation of Aspergillus Niger Spores to Surface Electrostatics: a Theoretical Approach Biointerphases. Dec, 2013 | Pubmed ID: 24706122 The effect of medium pH on conidial aggregation during submerged cultivation of Aspergillus niger is considered to originate from the electrostatic surface properties of the spores. As previously shown, these properties are greatly influenced by the presence of a melanin-containing surface coating covering the outer spore wall layer. The present study was designed to elucidate the impact of such a coating on the spores' surface potential and their electrostatic repulsion under acidic conditions. A Poisson-Boltzmann model was proposed and potential profiles across the surface coating of noninteracting and interacting spores were calculated. The surface potentials thus obtained were in line with the observed pH dependence of the zeta potential. This dependence was consistent with the outcome of aggregation experiments. Apparently contradictory results regarding the zeta potential and the aggregation behavior of the spores were obtained when the ionic strength was varied. However, both of these observations could be explained by the model.
Influence of Electrostatic Particle Interactions on the Properties of Particulate Coatings of Titanium Dioxide Journal of Colloid and Interface Science. Apr, 2014 | Pubmed ID: 24559704 Particulate coatings are used in a wide range of technical applications. The application affecting properties of these coatings depend strongly on the structure formation along the production process. Thus, primary and secondary particle size, size distribution, particle morphology as well as the particle-particle and particle-fluid interactions of the used formulation affect the resulting coating properties.