Mikrostruktur und Schmelzpunkt von stereoregulären Polymeren. Eine vorläufige experimentelle Beziehung für isotaktisches Polypropylen

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On the feasibility of using thermal gradients for active control of interlaminar stresses in laminated composites

In this paper, a method is proposed to actively control interlaminar stresses near the free edges of laminated composites by though-thickness thermal gradients. Theoretical solutions are given for optimal steady-state through-thickness temperature distributions under uniaxial loading that are required to eliminate or reduce the interlaminar stresses below a prescribed level. The optimal solutions are obtained by minimizing appropriate performance indices that are functions of the far-field properties, with respect to the through-thickness temperature differences. In the second part, an experimental investigation is conducted on a glass/epoxy cross-ply laminate with embedded piezoelectric sensors and a thermal heater. Through the experiment, the feasibility of the thermal control of interlaminar stresses is demonstrated.     

Measurement of the p to s wave branching ratio of 187Re beta decay from beta environmental fine structure

The mixed occurrence of s-wave and p-wave contributions in a first forbidden unique Gamow-Teller beta decay has been investigated for the first time by measuring the beta environmental fine structure (BEFS) in a 187Re crystalline compound. The experiment has been carried out with an array of eight AgReO4 thermal detectors operating at a temperature of approximately 100 mK. A fit of the observed BEFS spectrum indicates the p-wave electron emission as the dominant channel. The complete understanding of the BEFS distortion of the 187Re beta decay spectrum is crucial for future experiments aiming at the precise calorimetric measurement of the antineutrino mass.     

Cellular NADH and NADPH Conformation as a Real-Time Fluorescence-Based Metabolic Indicator under Pressurized Conditions

Cellular conformation of reduced pyridine nucleotides NADH and NADPH sensed using autofluorescence spectroscopy is presented as a real-time metabolic indicator under pressurized conditions. The approach provides information on the role of pressure in energy metabolism and antioxidant defense with applications in agriculture and food technologies. Here, we use spectral phasor analysis on UV-excited autofluorescence from Saccharomyces cerevisiae (baker’s yeast) to assess the involvement of one or multiple NADH- or NADPH-linked pathways based on the presence of two-component spectral behavior during a metabolic response. To demonstrate metabolic monitoring under pressure, we first present the autofluorescence response to cyanide (a respiratory inhibitor) at 32 MPa. Although ambient and high-pressure responses remain similar, pressure itself also induces a response that is consistent with a change in cellular redox state and ROS production. Next, as an example of an autofluorescence response altered by pressurization, we investigate the response to ethanol at ambient, 12 MPa, and 30 MPa pressure. Ethanol (another respiratory inhibitor) and cyanide induce similar responses at ambient pressure. The onset of non-two-component spectral behavior upon pressurization suggests a change in the mechanism of ethanol action. Overall, results point to new avenues of investigation in piezophysiology by providing a way of visualizing metabolism and mitochondrial function under pressurized conditions.     

Simultaneous determination of colchicine and febuxostat in rat plasma: Application in a rat pharmacokinetic study

A selective, sensitive and rapid LC–MS/MS method has been developed and validated as per US Food and Drug Administration regulatory guidelines for the simultaneous quantitation of colchicine and febuxostat in rat plasma. Colchicine and febuxostat were extracted from the rat plasma using 10% tert-butyl methyl ether in ethyl acetate using colchicine-d₆ as an internal standard (IS). The chromatographic separation of colchicine, febuxostat and the IS was achieved using a mobile phase comprising 5 mm ammonium formate and 0.025% formic acid in acetonitrile (20:80, v/v) in isocratic mode on an Eclipse XDB-C₁₈ column. The injection volume and flow rate were 5.0 μl and 0.9 ml/min, respectively. Colchicine and febuxostat were detected by positive electrospray ionization in multiple reaction monitoring mode using transition pairs (Q1 → Q3) of m/z 400.10 → 358.10 and 317.05 → 261.00, respectively. The assay was linear in the ranges of 0.25–254 and 2.60–622 ng/ml for colchicine and febuxostat, respectively. The inter- and intra-day precision values were 0.58–13.0 and 1.03–4.88% for colchicine and febuxostat, respectively. No matrix or carryover effects were observed during the validation. Both analytes were stable on the bench-top, in the autosampler and in storage (freeze–thaw cycles and long-term storage at −80 ° C). A pharmacokinetic study in rats was performed to show the applicability of the validated method.     

One-pot three-component tandem reaction: Synthesis of aryl/alkyl cyanamides libraries and their further conversion into tetrazole derivatives

We have developed methodology for the synthesis of aryl/alkyl cyanamides from amines in one-pot four steps reaction using cheap, readily available and air stable copper source as catalyst under mild reaction conditions. We have also studied the application of cyanamides. In this connection, we could construct aryl tetrazolamine from cyanamides using click reaction     

Progress in drug delivery to the central nervous system by the prodrug approach

This review describes specific strategies for targeting to the central nervous system (CNS). Systemically administered drugs can reach the brain by crossing one of two physiological barriers resistant to free diffusion of most molecules from blood to CNS: the endothelial blood-brain barrier or the epithelial blood-cerebrospinal fluid barrier. These tissues constitute both transport and enzymatic barriers. The most common strategy for designing effective prodrugs relies on the increase of parent drug lipophilicity. However, increasing lipophilicity without a concomitant increase in rate and selectivity of prodrug bioconversion in the brain will result in failure. In these regards, consideration of the enzymes present in brain tissue and in the barriers is essential for a successful approach. Nasal administration of lipophilic prodrugs can be a promising alternative non-invasive route to improve brain targeting of the parent drugs due to fast absorption and rapid onset of drug action. The carrier-mediated absorption of drugs and prodrugs across epithelial and endothelial barriers is emerging as another novel trend in biotherapeutics. Several specific transporters have been identified in boundary tissues between blood and CNS compartments. Some of them are involved in the active supply of nutrients and have been used to explore prodrug approaches with improved brain delivery. The feasibility of CNS uptake of appropriately designed prodrugs via these transporters is described in detail.     

Modified Cyclodextrins as Enantioselective Hosts for Amino Acids

Two modified β‐cyclodextrins, H‐2 and H‐3 , having a flexible appended moiety were studied for the chiral discrimination of the enantiomers of various amino acids by means of fluorescence as signaling option. These hosts quenched the fluorescence intensities of amino acids upon binding. The d‐ enantiomers were better recognized by these hosts. The association constants (K_s) and enantioselectivity factors (α) of the host?guest complexes were calculated.     

Synthesis, spectral and oxidase studies of a new diamide copper(II) complex with pendant benzimidazolyl groups

A new benzimidazole-based diamide ligand-N,N'-bis(alanine-2-benzimidazolyl) hexanediamide (ABHA) has been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(ABHA)X2].nH2O,where X is an exogenous anionic ligand (X=Cl-,NO3-). Low temperature EPR spectra has been obtained that shows gparallel>gperpendicular>2.0024, indicating a tetragonal geometry in the solution state. The complexes display a quasi-reversible redox wave due to the Cu(II)/Cu(I) reduction process. E1/2 values shift anodically as NO3-相似文献