Phase structure and electrochemical characteristics of CaNi4.7Mn0.3 hydrogen storage alloy by mechanical alloying

Journal of Solid State Electrochemistry - In this paper, we study systematically the effect of ball/powder weight ratio on the morphological, structural, and electrochemical properties of...     

Acrolein and Copper as Competitive Effectors of α-Synuclein

Mounting evidence supports the role of amyloidogenesis, oxidative stress, and metal dyshomeostasis in the development of neurodegenerative disorders. Parkinson's Disease is characterized by α-synuclein (αSyn) accumulation and aggregation in brain regions, also promoted by Cu²⁺. αSyn is modified by reactive carbonyl species, including acrolein (ACR). Notwithstanding these findings, the interplay between ACR, copper, and αSyn has never been investigated. Therefore, we explored more thoroughly the effects of ACR on αSyn using an approach based on LC-MS/MS analysis. We also evaluated the influence of Cu²⁺ on the protein carbonylation and how the ACR modification impacts the Cu²⁺ binding and the production of Reactive Oxygen Species (ROS). Finally, we investigated the effects of ACR and Cu²⁺ ions on the αSyn aggregation by dynamic light scattering and fluorescence assays. Cu²⁺ regioselectively inhibits the modification of His50 by ACR, the carbonylation lowers the affinity of His50 for Cu²⁺ and ACR inhibits αSyn aggregation both in the presence and in the absence of Cu²⁺.     

Stochastic optimization in supply chain networks: averaging robust solutions

We propose a novel robust optimization approach to analyze and optimize the expected performance of supply chain networks. We model uncertainty in the dema     

Physical Evidence of Stress-Induced Conformational Changes in Polymers

Background

Polymer mechanics and characterization is an active area of research where a keen effort is directed towards gaining a predictive and correlative relationship between the applied loads and the specific conformational motions of the macromolecule chains.

Objective

Therefore, the objective of this research is to introduce the preliminary results based on a novel technique to in situ probe the mechanical properties of polymers using non-invasive, non-destructive, and non-contact terahertz spectroscopy.

Methods

A dielectric elastomer actuator (DEA) structure is used as the loading mechanism to avoid obscuring the beam path of transmission terahertz time-domain spectroscopy. In DEAs, the applied voltage results in mechanical stresses under the active electrode area with far-reaching stretching in the passive area. Finite element analysis is used to model and simulate the DEA to quantify the induced stresses at the observation site over a voltage range spanning from 0 V to 3000 V. Additionally, a novel analysis technique is introduced based on the Hilbert-Huang transform to exploit the time-domain signals of the ultrathin elastomeric film and to defy the limits set forth by the current state-of-the-art analysis techniques.

Results

The computational result shows a nonlinear relationship between the effective stresses and the applied voltage. Analysis of the terahertz time-domain signals shows a shift in the delay times and a decrease in signal peak amplitudes, whereas these characteristics are implicitly related to the change in the index of refraction.

Conclusions

In all, the results evidentially signify the interrelationship between the conformational changes and applied mechanical stress.

     

Oxygen dependence of two-photon activation of zinc and copper phthalocyanine tetrasulfonate in Jurkat cells

Abstract Photodynamic therapy (PDT), the use of light-activated drugs, is a promising treatment of cancer as well as several nonmalignant conditions. However, the efficacy of one-photon (1-gamma) PDT is limited by hypoxia, which can prevent the production of the cytotoxic singlet oxygen ((1)O(2)) species, leading to tumor resistance to PDT. To solve this problem, we propose an irradiation protocol based on a simultaneous, two-photon (2-gamma) excitation of the photosensitizer (Ps). Excitation of the Ps triplet state leads to an upper excited triplet state T(n) with distinct photochemical properties, which could inflict biologic damage independent of the presence of molecular oxygen. To determine the potential of a 2-gamma excitation process, Jurkat cells were incubated with zinc or copper phthalocyanine tetrasulfonate (ZnPcS(4) or CuPcS(4)). ZnPcS(4) is a potent (1)O(2) generator in 1-gamma PDT, while CuPcS(4) is inactive under these conditions. Jurkat cells incubated with either ZnPcS(4) or CuPcS(4) were exposed to a 670 nm continuous laser (1-gamma PDT), 532 nm pulsed-laser light (2-gamma PDT), or a combination of 532 and 670 nm (2-gamma PDT). The efficacy of ZnPcS(4) to photoinactivate the Jurkat cells decreased as the concentration of oxygen decreased for both the 1-gamma and 2-gamma protocols. In the case of CuPcS(4), cell phototoxicity was measured only following 2-gamma irradiation, and its efficacy also decreased at a lower oxygen concentration. Our results suggest that for CuPcS(4) the T(n) excited state can be populated after 2-gamma irradiation at 532 nm or the combination of 532 and 670 nm light. Dependency of phototoxicity upon aerobic conditions for both 1-gamma and 2-gamma PDT suggests that reactive oxygen species play an important role in 1-gamma and 2-gamma PDT.     

Reactions of 4-(2-aminothiazole-4-yl)-3-methyl-5-oxo-1-phenyl-2-pyrazoline. Synthesis of thiazolo[3,2- a ]pyrimidine and imidazo[2,1- b ]thiazole derivatives

4-(2-Aminothiazol-4-yl)-3-methyl-5-oxo-1-phenyl-2-pyrazoline was synthesized via the reaction of 4-bromoacetyl-3-methyl-5-oxo-1-phenyl-2-pyrazoline with thiourea [7] and was transformed to related fused heterocyclic systems. The antifungal and antibacterial studies revealed in some cases excellent biocidal properties.     

Validated stability-indicating methods for the determination of nizatidine in the presence of its sulfoxide derivative

Four new selective, precise, and accurate methods are described for the determination of nizatidine (NIZ) in the presence of its sulfoxide derivative in both the raw material and pharmaceutical preparations. Method A is based on zero-order (0D), first-derivative (1D), and second-derivative (2D) spectrophotometric measurement of NIZ in aqueous solution at the zero-crossing point of its sulfoxide derivative (at 314, 295-334, and 318-348 nm, respectively). Method B is a 1DD spectrophotometric method based on the simultaneous use of the first derivative of the ratio spectra and the measurement of peak amplitude at 297 nm. Method C uses a solvent-induced derivative-difference spectrophotometry with deltaD1 measurement from peak to peak at 315-345 nm. Method D involves quantitative densitometric evaluation of a mixture of the drug and its sulfoxide derivative after separation by high-performance thin-layer chromatography on silica gel plates with chloroform-methanol (9 + 1, v/v) as the mobile phase; Rf values for NIZ and its sulfoxide derivative were 0.4 and 0.2, respectively. The spot was scanned at 254 nm. The first-derivative spectrophotometric method was used to investigate the kinetics of the hydrogen peroxide degradation process at different temperatures. The apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. The results obtained by the proposed methods were analyzed statistically and compared with those obtained by the official method. These methods are suitable as stability-indicating for the determination of NIZ in the presence of its oxidation-induced degradation product (sulfoxide derivative) either in the bulk powder or in pharmaceutical preparations.     

Synthesis of new quinoxalinophenazinediones and tetrahydrobenzodipyrrolotetrones of biological interest

The reaction of two equivalents of sodium azide with diarylaminodibromo-p-benzoquinone (I) in DMF for 15–24 h produced quinoxalinophenazinediones together with a byproduct identified as diarylaminodiaminobenzoquinone. On the other hand, the reaction of bromanil with active methylenes, such as diethyl malonate and ethyl acetoacetate, resulted in disubstitution products which, on treatment with primary amines, cyclized into benzodipyrroletetrones. Comparative antifungal and antibacterial studies were made.     

Inhibitory Effects of Tunisian Marine Algal Extracts on Digestive Lipases

The lipase inhibitory activity of ethanol extracts obtained from some marine algae collected on the Tunisian coast was evaluated. Caulerpa prolifera extract markedly reduced both dog gastric (DGL) and human pancreatic lipase (HPL) activities. Generally, the inhibition reached 100% after 40 to 60 min of incubation depending on lipase types and on substrates used. Moreover, the inhibitory effect of C. prolifera extract on lipases appeared to be accelerated by adding bile salts, which likely modified the interface and allowed the inhibitory compound to inactivate the lipase. The separation of C. prolifera extract by thin-layer chromatography (TLC) resulted in eight fractions showing efficient inhibition rate against DGL, compared to the crude extract. In the case of HPL, TLC fractionation reduced the inhibitory rates, suggesting that the effect of algal extract on lipases may be caused by a synergetic action of several compounds within the extract. High-performance liquid chromatograph separation resulted in isolation of a major compound displaying high inhibition capacity of HPL activity. Caulerpa prolifera extract may therefore be useful in developing antiobesity drugs.