Parameter-dependent <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> Control for Time-varying Delay Polytopic Systems

This paper addresses the robust stabilization and H _∞ control problem for a class of linear polytopic systems with continuously distributed delays. The control objective is to design a robust H _∞ controller that satisfies some exponential stability constraints on the closed-loop poles. Using improved parameter-dependent Lyapunov Krasovskii functionals, new delay-dependent conditions for the robust H _∞ control are established in terms of linear matrix inequalities.     

“Printing” DNA Strand Patterns on Small Molecules with Control of Valency,Directionality, and Sequence

The incorporation of synthetic molecules as corner units in DNA structures has been of interest over the last two decades. In this work, we present a facile method for generating branched small molecule‐DNA hybrids with controllable valency, different sequences, and directionalities (5′–3′) using a “printing” process from a simple 3‐way junction structure. We also show that the DNA‐imprinted small molecule can be extended asymmetrically using polymerase chain reaction (PCR) and can be replicated chemically. This strategy provides opportunities to achieve new structural motifs in DNA nanotechnology and introduce new functionalities to DNA nanostructures.     

Time-resolved spectroscopy of freestanding GaN layers grown by halide vapour phase epitaxy

Freestanding GaN layers of various thicknesses grown by HVPE have been studied by time-resolved spectroscopy combined with structural and electrical measurements. We have observed an increase of the PL lifetime with increasing layer thickness; however, a saturation of the recombination times has been detected for the GaN layers thicker than 400 μm. We explain the observed thickness-dependent behavior of the decay times by competition of two nonradiative mechanisms; namely, for layers with thickness less than 400 μm the main nonradiative channel is related to the structural defects, while in thicker layers the recombination decay time is limited by impurities and/or vacancies.     

On deformations of maps and curve singularities

We study several deformation functors associated to the normalization of a reduced curve singularity . The main new results are explicit formulas, in terms of classical invariants of (X, 0), for the cotangent cohomology groups T ⁱ , i  =  0,1,2, of these functors. Thus we obtain precise statements about smoothness and dimension of the corresponding local moduli spaces. We apply the results to obtain explicit formulas, respectively, estimates for the -codimension of a parametrized curve singularity, where denotes the Mather–Wall group of left-right equivalence.     

Biodegradation of a synthetic co-polyester by aerobic mesophilic microorganisms

The aerobic biological degradation of the synthetic aliphatic-aromatic co-polyester Ecoflex™ (BASF) by 29 strains of enzyme-producing soil bacteria, fungi and yeasts was investigated at moderate environmental conditions. Previous studies had shown that these materials could be degraded but these studies were done under thermophilic conditions. In this paper, a screening procedure was developed to assess the biodegradability of the co-polyester at ambient environmental conditions and to investigate the mechanism of biodegradation. Results showed that the aliphatic-aromatic co-polyester could be degraded by a number of different microorganisms. However, after 21 days exposure to even the most promising cultures of pure microorganisms, only partial degradation of the Ecoflex™ was accomplished and only a few samples showed visible signs of degradation as loosely defined by the mechanical weakening of the films. Weight loss was not as obvious as the visual degradation and suggested broader types of microbial attack. The bacteria studied preferentially degraded the bonds between aliphatic components of the copolymer and the rate of biodegradation of oligomers was appreciably faster than that for the polymer chains. Using GC-MS techniques, degradation intermediates were identified to be the monomers of the co-polyester. Gel permeation chromatography results suggested exo-enzyme type degradation, where the microbes hydrolysed the ester bonds at the termini of the polymeric chains preferentially.     

pH-temperature Responsive Hydrogel-Mediated Delivery of Exendin-4 Encapsulated Chitosan Nanospheres for Sustained Therapeutic Efficacy in Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2D) is a chronic, obesity-related, and inflammatory disorder characterize by insulin resistance, inadequate insulin secretion, hyperglycemia, and excessive glucagon secretion. Exendin-4 (EX), a clinically established antidiabetic medication that acts as a glucagon-like peptide-1 receptor agonist, is effective in lowering glucose levels and stimulating insulin secretion while significantly reducing hunger. However, the requirement for multiple daily injections due to EX's short half-life is a significant limitation in its clinical application, leading to high treatment costs and patient inconvenience. To address this issue, an injectable hydrogel system is developed that can provide sustained EX release at the injection site, reducing the need for daily injections. In this study, the electrospray technique is examine to form EX@CS nanospheres by electrostatic interaction between cationic chitosan (CS) and negatively charged EX. These nanospheres are uniformly dispersed in a pH-temperature responsive pentablock copolymer, which forms micelles and undergoes sol-to-gel transition at physiological conditions. Following injection, the hydrogel gradually degraded, exhibiting excellent biocompatibility. The EX@CS nanospheres are subsequently released, maintaining therapeutic levels for over 72 h compared to free EX solution. The findings demonstrate that the pH-temperature responsive hydrogel system containing EX@CS nanospheres can be a promising platform for the treatment of T2D.     

Double Yielding in a Styrene/Butadiene Star Block Copolymer

Summary: The morphology and tensile deformation behaviour of a highly asymmetric styrene/butadiene star block copolymer (polystyrene (PS) content = 74%) containing random PS‐co‐PB (polybutadiene) copolymer as a rubbery phase were investigated. The existence of double yielding, similar to that observed in some semicrystalline polymers, was detected in this nanostructured amorphous polymer. The observed phenomenon may be correlated with two different micromechanical processes taking place at the initial stage of deformation.

The stress‐strain curve of the star block copolymer prepared here (each curve represents a different method). The two yield points are clearly visible (labelled I and II).     

Research on Electroanalytical Chemical Methods for Trace Metal Speciation in Sea Water Samples

Since bioavalability of a trace metal in natural waters is affected by its chemical forms, the speciation of a trace metal becomes more and more important in environmental chemistry. Differential pulse anodic stripping voltammetry (DPASV) titration procedures are developed and applied to identify organic trace metal species of copper (Cu), lead (Pb) and zinc (Zn) in sea water and to determine their complexing capacity.     

Investigation for Differentiation of Bounding Strength Of Metals in Sediments

Only part of the metal present in sediments are involved in short-term geochemical processes and/or are bioavailable. Hydrous Fe- and Mn-oxides as well as organic matter partly as coatings on films on detail grains, are important substances for the interaction with dissolved metal species in aquatic systems.     

Strong Law of Large Numbers for Betti Numbers in the Thermodynamic Regime

Journal of Statistical Physics - We establish the strong law of large numbers for Betti numbers of random ?ech complexes built on $${\mathbb {R}}^N$$ -valued binomial point processes and...