Counterion condensation and effective charge of PAMAM dendrimers

PAMAM dendrimers are used as a model system to investigate the effects of counterion condensation and the effective charge for spherical polyelectrolytes. Because of their amino groups, PAMAM dendrimers are weak polyelectrolytes. Lowering the pH results in an increasing protonation of the amino groups which is monitored via the proton chemical shifts of the adjacent CH2 groups. The effective charge is determined from a combination of diffusion and electrophoresis NMR. The fraction of the charges, which are effective for the interaction with an external electric field or other charges, decreases with increasing generation (size) of the dendrimers

alpha-Amylase Production in Fed BatchCultivation of Bacillus caldolyticus: An Interpretation of FermentationCourseUsing 2-D Gel Electrophoresis

The conditions for increased production of thermostable a-amylase from Bacillus caldolyticus DSM 405 were investigated. Preliminary experiments in batch shake flasks led to an optimized initial cultivation medium. Shake flask experiments in extended-batch and in fed-batch mode of operation indicated that the a-amylase production was enhanced by continuous feeding of starch. The activity of the a-amylase with optimized initial medium in batch-operated shake flasks was 5.7 U mL–1 compared to 15.4U mL–1 in the extended-batch culture and 21 U mL–1 in fed-batch culture. The improvements were achieved by avoiding any excess of starch in medium that led to accumulation of glucose followed by acetate formation. Adding casitone as the second component of the feeding solution in an aerated and agitated fed-batch bioreactor (3-liter working volume) led to an increased -amylase activity of up to 163.7 U mL.–1 All phases of cultivation were analyzed using 2D-gel electrophoresis in combination with nano LC-ESI-MS/MS for identification of altered proteins. Pyruvate kinase, 6-phosphofructokinase, GltC, anti-sigma F factor, glycogen synthase and several important variable proteins were detected. With help of these results, potential improvements of a two-component feeding strategy are discussed

Разработка модуля детектирования повреждений на крышах домов для геоинформационной CRM системы

Одной из возможностей геоинформационной CRM-системы является обнаружение человеком дефектом крыш домов с аэрофотоснимка. После анализа принимается решение о предложении услуг ремонта крыши для человека. Данная стратегия может быть оптимизирована путем внедрения модуля, позволяющего определять повреждения крыш без участия человека.One of the features of the geographic information CRM-system is the detection by person of a roof defect from an air photo. After analysis, the decision is made to offer roof repair services for a person. This strategy can be optimized by introducing a module that allows to determine roof damage without human intervention

Scaling in a continuous time model for biological aging

In this paper we consider a generalization to the asexual version of the Penna model for biological aging, where we take a continuous time limit. The genotype associated to each individual is an interval of real numbers over which Dirac $\delta$--functions are defined, representing genetically programmed diseases to be switched on at defined ages of the individual life. We discuss two different continuous limits for the evolution equation and two different mutation protocols, to be implemented during reproduction. Exact stationary solutions are obtained and scaling properties are discussed.Comment: 10 pages, 6 figure

Self-diffusion of low-generation PAMAM dendrimers with hydroxyl surface groups in solutions: A general regularity

An experimental study of the self-diffusion and nuclear magnetic relaxation of poly(amidoamine) dendrimers with hydroxyl surface groups (PAMAM-OH) dissolved in methanol over a wide range of concentration (ψ) is reported. It is shown that experimental concentration dependences of PAMAM-OH self-diffusion coefficients (D) can be reduced to the so-called generalized ψ dependence. Over macromolecular concentration range studied, the generalized concentration dependence of PAMAM-OH D coincides with analogous curve obtained for poly(allylcarbosilane) dendrimers of high generations. This result confirms the existence of common regularities of the dendritic macromolecule self-diffusion, and their independence of the individual physicochemical and structural properties of dendrimer, solvent, and features of their interactions in the given systems. The concentration dependence of the PAMAM-OH diffusion also exhibits a clear signature of an inflexible molecule. © 2003 Elsevier Ltd. All rights reserved

On the importance of hydrodynamic interactions in polyelectrolyte electrophoresis

The effect of hydrodynamic interactions on the free-solution electrophoresis of polyelectrolytes is investigated with coarse-grained molecular dynamics simulations. By comparing the results to simulations with switched-off hydrodynamic interactions, we demonstrate their importance in modelling the experimentally observed behaviour. In order to quantify the hydrodynamic interactions between the polyelectrolyte and the solution, we present a novel way to estimate its effective charge. We obtain an effective friction that is different from the hydrodynamic friction obtained from diffusion measurements. This effective friction is used to explain the constant electrophoretic mobility for longer chains. To further emphasize the importance of hydrodynamic interactions, we apply the model to end-labeled free-solution electrophoresis.Comment: 15 pages, 7 figures; accepted for publication in J. Phys.: Condens. Matte

Biomechanical Properties of the Internal Limiting Membrane after Intravitreal Ocriplasmin Treatment

Purpose: To assess the stiffness of the human internal limiting membrane (ILM) and evaluate potential changes of mechanical properties following intravitreal ocriplasmin injection for vitreomacular traction. Methods: This is an interventional comparative case series of 12 surgically excised ILM specimens consecutively obtained from 9 eyes of 9 patients after unsuccessful pharmacologic vitreolysis with ocriplasmin. During the same time period, 16 specimens from 13 other eyes without ocriplasmin treatment were harvested during vitrectomy and served as controls. All patients presented with macular holes or vitreomacular traction and underwent vitrectomy with ILM peeling either with or without brilliant blue (BB) staining. All specimens were analyzed using atomic force microscopy with scan regions of 25 x 25 mu m. In all specimens, both the retinal side and vitreal side of the ILM were analyzed. Results: Atomic force microscopy revealed no significant differences in elasticity of ILM specimens removed from eyes with or without ocriplasmin treatment. Undulated areas of the retinal side presented stiffer than the vitreal side of the ILM. Topographical mapping of both the vitreal and retinal side of the ILM showed no apparent alteration of the morphology in ocriplasmin-treated eyes compared to untreated eyes. Staining with BB resulted in an increase of tissue stiffness. Conclusions: Intravitreal injection of ocriplasmin does not change biomechanical properties of the human ILM. There is no evidence of a potential enzymatic effect of ocriplasmin interfering with the stiffness of this basement membrane. (C) 2016 S. Karger AG, Base

An anode‐free Zn–graphite battery

The anode-free battery concept is proposed to pursue the aspiration of energy-dense, rechargeable metal batteries, but this has not been achieved with dual-ion batteries. Herein, the first anode-free Zn–graphite battery enabled by efficient Zn plating–stripping onto a silver-coated Cu substrate is demonstrated. The silver coating guides uniform Zn deposition without dendrite formation or side reaction over a wide range of electrolyte concentrations, enabling the construction of anode-free Zn cells. In addition, the graphite cathode operates efficiently under reversible bis(trifluoromethanesulfonyl)imide anion (TFSI−) intercalation without anodic corrosion. An extra high-potential TFSI− intercalation plateau is recognized at 2.75 V, contributing to the high capacity of graphite cathode. Thanks to efficient Zn plating–stripping and TFSI− intercalation–deintercalation, an anode-free Zn–graphite dual-ion battery that exhibits impressive cycling stability with 82% capacity retention after 1000 cycles is constructed. At the same time, a specific energy of 79 Wh kg−1 based on the mass of cathode and electrolyte is achieved, which is over two times higher than conventional Zn–graphite batteries (−1)

Splitting of Folded Strings in AdS_4*CP^3

We study classically splitting of two kinds of folded string solutions in AdS_4*CP^3. Conserved charges of the produced fragments are computed for each case. We find interesting patterns among these conserved charges.Comment: minor changes, 14 pages, no figure