Thermotropic liquid crystalline copolyesters. II. Synthesis and thermal characterization of copolyesters of terephthalic acid,methyl hydroquinone and 1,4-butane diol

The synthesis and thermodynamic evaluations of a series of random copolyesters based on terephthalic acid, methyl hydroquinone and 1,4-butane diol are presented. The copolyester composition was varied by altering the relative concentrations of methyl hydroquinone and 1,4-butane diol. The copolyesters display thermotropic transitions. The enthalpy changes during mesophasic transition display a minimum corresponding to equimolar composition. The copolyester with 75 mol% of spacer diol exhibited the lowest nematic transition temperature (190-6°C). At this composition the nematic mesophase was most stable (δT_N = 115-6°C). ΔH_N-1 and ΔS_N-1 decrease with increasing rigid diol content. The isotropization temperatures were almost comparable since the largest mesogenic residues are similar in aspect ratio. These residues are required to melt prior to isotropization.     

Capture of Co(II) from its aqueous EDTA-chelate by DTPA-modified silica gel and chitosan

The adsorption of Co(II) by diethylenetriaminepentaacetic acid (DTPA)-modified silica gel and chitosan in the presence of EDTA and other interfering species was studied. Co(II) removal ranged from 93% to 96% from the solutions where Co(II) was totally chelated by EDTA. The amount of oxalate or Fe(II) did not affect the adsorption of Co(II) in the case of DTPA-chitosan. However, increasing the amount of oxalate enhanced the adsorption performance of DTPA-silica gel, probably due to the formation of new active sites on the silica gel surface. DTPA-chitosan was also effective in simulated decontamination solutions. For DTPA-silica gel, the rate of adsorption of free Co(II) was controlled by pore diffusion, but the rate of adsorption of Co(II)EDTA was controlled by the surface chelation reaction, which was attributed to the inhibited diffusion of Co(II)EDTA inside the silica gel mesopores. However, the macroporous structure of DTPA-chitosan enabled pore diffusion of both Co(II) and Co(II)EDTA. The equilibrium isotherms of DTPA-silica gel were best described by a BiLangmuir model, in which there are two different adsorption sites on the silica gel surface assigned to different speciations of DTPA. For DTPA-chitosan, the data fit best with a Sips model, which indicates system heterogeneity. Finally, measurements with capillary electrophoresis showed an increase in dissolved EDTA during adsorption, demonstrating the ability of DTPA-modified adsorbents to release Co(II) from its EDTA chelate. This promising result can provide a basis for applying the studied materials to the treatment of water effluents containing Co(II) chelated by EDTA by a simple one-step adsorption process.     

Biogenic amines in dry sausages during shelf-life storage

 Supercritical fluid extraction (SFE) with subsequent HPLC analysis was performed in order to determine the amount of capsaicinoids in paprika and chillie powder samples. The extraction yields obtained by SFE were compared to those obtained by organic solvent extraction and were found to be comparable or slightly lower. The advantages of SFE are shorter extraction times, less sample preparation needed prior to HPLC analysis and fewer interfering peaks in the chromatograms. In addition, the SFE method developed (extraction temperature=80 ^°C, density= 0.75 g/ml, modifier=20 μl water) was shown to be suitable for analysis of capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin) that are present over a wide range of concentrations (10–1400 μg/g) in the samples. Received: 12 July 1996/Revised version: 26 August 1996     

Multicenter Collaborative Trial Evaluation of a Method for Detection of Human Adenoviruses in Berry Fruit

The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5?×?10² and 5?×?10⁴?PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow.     

Waste fly ash–ZnO as a novel sunlight-responsive photocatalyst for dye discoloration

Treating waste with a waste material using freely available solar energy is the most effective way towards sustainable future. In this study, a novel photocatalyst, partly derived from waste material from the coal industry, was developed. Fly ash hybridized with ZnO (FA—Zn) was synthesized as a potential photocatalyst for dye discoloration. The synthesized photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet—visible/near infra-red spectroscopy. The photocatalytic activity was examined with the discoloration of methylene blue used as synthetic dye wastewater. All the experiments were performed in direct sunlight. The photocatalytic performance of FA—Zn was found to be better than that of ZnO and the conventionally popular TiO₂. The Langmuire—Hinshelwood model rate constant values of ZnO, TiO₂, and FA—Zn were found to be 0.016 min^-1, 0.017 min^-1, and 0.020 min^-1, respectively. There were two reasons for this: (1) FA—Zn was able to utilize both ultraviolet and visible parts of the solar spectrum, and (2) its Brunauere—Emmette—Teller surface area and porosity were significantly enhanced. This led to increased photon absorption and dye adsorption, thus exhibiting an energy-efficient performance. Therefore, FA—Zn, partly derived from waste, can serve as a suitable material for environmental remediation and practical solar energy applications.     

Variational autoencoder for prosody-based speaker recognition

This paper describes a novel end-to-end deep generative model-based speaker recognition system using prosodic features. The usefulness of variational autoencoders (VAE) in learning the speaker-specific prosody representations for the speaker recognition task is examined herein for the first time. The speech signal is first automatically segmented into syllable-like units using vowel onset points (VOP) and energy valleys. Prosodic features, such as the dynamics of duration, energy, and fundamental frequency ( $F_0$), are then extracted at the syllable level and used to train/adapt a speaker-dependent VAE from a universal VAE. The initial comparative studies on VAEs and traditional autoencoders (AE) suggest that the former can efficiently learn speaker representations. Investigations on the impact of gender information in speaker recognition also point out that gender-dependent impostor banks lead to higher accuracies. Finally, the evaluation on the NIST SRE 2010 dataset demonstrates the usefulness of the proposed approach for speaker recognition.     

Nano-Theranostic Modality for Visualization of the Placenta and Photo-Hyperthermia for Potential Management of Ectopic Pregnancy

Ectopic pregnancy (EP) is the leading cause of maternity-related death in the first trimester of pregnancy. Approximately 98% of ectopic implantations occur in the fallopian tube, and expedient management is crucial for preventing hemorrhage and maternal death in the event of tubal rupture. Current ultrasound strategies misdiagnose EP in up to 40% of cases, and the failure rate of methotrexate treatment for confirmed EP exceeds 10%. Here the first theranostic strategy for potential management of EP is reported using a near-infrared naphthalocyanine dye encapsulated within polymeric nanoparticles. These nanoparticles preferentially accumulate in the developing murine placenta within 24 h following systemic administration, and enable visualization of implantation sites at various gestational stages via fluorescence and photoacoustic imaging. These nanoparticles do not traverse the placental barrier to the fetus or impact fetal development. However, excitation of nanoparticles localized in specific placentas with focused NIR light generates heat (>43 °C) sufficient for disruption of placental function, resulting in the demise of targeted fetuses with no effect on adjacent fetuses. This novel approach would enable diagnostic confirmation of EP when current imaging strategies are unsuccessful, and elimination of EP could subsequently be achieved using the same nano-agent to generate localized hyperthermia resulting in targeted placental impairment.