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  • Author or Editor: L. Cao x
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Summary

Two rapid, sensitive and reproducible methods for the determination of baclofen(BAL) in urine and plasma based on high-performance liquid chromatography (HPLC) with UV-vis and fluorescent detection, respectively, were developed for the first time using a new synthesized fluorescent label, 6-oxy-(N-succinimidylacetate)-9-(2′-methoxycarbonyl) fluorescein (SAMF). The optimal derivatization yield was achieved in borate buffer (pH 8.0) for 15 min at room temperature (25 °C). With a mixture of methanol and water containing 5 mmol L−1 sodium citrate buffer (pH 5.0) as mobile phase, BAL was determined at λ = 455 nm with UV-vis detection and at λ ex/λ em = 488/520 nm with FD detection. The detection limits are 1.065 × 10−3 mg mL−1 and 1.065 × 10−2 mg mL−1 with HPLC-UV-vis and HPLC-FD, respectively. The proposed method has been successfully applied to the analysis of BAL in human urine and plasma samples. The established method is rapid (15 min of derivatization process and 10 min of chromatographic run), reproducible and sensitive.

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Abstract  

One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%) of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates for thermal conductivity enhancement of organic PCMs.

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Abstract  

A series of PA-TD mixtures were prepared and their thermal properties were studied by DSC and thermal conductivity measurement. The phase diagram of the binary system was constructed, which showed an eutectic behavior for the solid-liquid equilibrium line. The eutectic composition of the binary system was at the mass fraction of TD near 0.7 with an eutectic temperature of about 29°C. At TD side, PA was partially miscible in the TD solid matrix and the solid phase transition of TD had an effect on the solidus line. The eutectic composition mixture could be viewed as a new phase change material with large thermal energy storage capacity.

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Abstract  

The effects of multi-walled carbon nanotubes (MWNTs) on the phase change enthalpy (ΔH) and the thermal conductivity (κ) of a solid-liquid phase change materials (PCM), palmitic acid (PA), have been investigated. The results showed that both the ΔH and the κ of the composite were lower than that of PA when the loading of MWNTs was small. As the concentration of MWNTs in the composites increased, the ΔH of the composites was slightly improved and then decreased linearly. However, the κ of the composites was monotonously increased from the minimum value. When the loading of MWNTs increased to 5% and no surfactant was added, the κ of the composite was enhanced to be 26% higher than that of PA. The κ of the composite could be enhanced by CTAB instead of SDBS when the loading of MWNTs was small, as SDBS showed no obvious effect on the κ of the composites. Furthermore, the effects of surface modification of MWNTs on the ΔH and the κ of the composites have also been investigated.

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Abstract

In this study, the ability of microRNA-1906 (miR-1906) to attenuate bone loss in osteoporosis was evaluated by measuring the effects of a miR-1906 mimic and inhibitor on the cellular toxicity and cell viability of MC3T3‐E1 cells. Bone marrow-derived macrophage (BMM) cells were isolated from female mice, and tartrate-resistant acid phosphatase signalling was performed in miR-1906 mimic-treated, receptor-activated nuclear factor kappa-B (NF-κB) ligand (RANKL)-induced osteoclasts. In-vivo, osteoporosis was induced by ovariectomy (OVX). Rats were treated with 500 nmol/kg of the miR-1906 mimic via intrathecal administration for 10 consecutive days following surgery. The effect of the miR-1906 mimic on bone mineral density (BMD) in OVX rats was observed in the whole body, lumbar vertebrae and femur. Levels of biochemical parameters and cytokines in the serum of miR-1906 mimic-treated OVX rats were analysed. The mRNA expression of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), p-38 and NF-κB in tibias of osteoporotic rats (induced by ovariectomy) was observed using quantitative reverse-transcription polymerase chain reaction. Treatment with the miR-1906 mimic reduced cellular toxicity and enhanced the cell viability of MC3T3‐E1 cells. Furthermore, osteoclastogenesis in miR-1906 mimic-treated, RANKL-induced osteoclast cells was reduced, whereas the BMD in the miR-1906 mimic-treated group was higher than in the OVX group of rats. Treatment with the miR-1906 mimic also increased levels of biochemical parameters and cytokines in the serum of ovariectomised rats. Finally, mRNA expression levels of TLR4, MyD88, p-38 and NF-κB were lower in the tibias of miR-1906 mimic-treated rats than in those of OVX rats. In conclusion, the miR-1906 mimic reduces bone loss in rats with ovariectomy-induced osteoporosis by regulating the TLR4/MyD88/NF‐κB pathway.

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Abstract  

During the past decade, interest has increased in qualifying and quantifying the threat posed to the public by the illegal use of radionuclides. In order to take investigations beyond the laboratory bench into more realistic scenarios, environmental and safety considerations dictate that these studies be performed on stable and benign surrogates. This paper discusses some of these studies, specifically the use of cerium dioxide for actinide ceramics and calcium and natural strontium ceramics for those based on 90Sr.

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Abstract  

We prepared PANI/tetradecanol/MWNTs composites via in-situ polymerization. DSC results indicated that the composites are good form-stable phase change materials (PCMs) with large phase change enthalpy of 115 J g−1. The MWNTs were randomly dispersed in the composites and significantly enhanced the thermal conductivity of the PCMs from 0.33 to 0.43 W m−1 K−1. The form-stable PCMs won’t liquefy even it is heated at 80°C, so that the MWNTs were fixed in the composite and the phase separation of the MWNTs from PANI/tetradecanol/MWNTs composites won’t occur.

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Polyaniline/1-tetradecanol composites

Form-stable PCMS and electrical conductive materials

Journal of Thermal Analysis and Calorimetry
Authors: J. Zeng, J. Zhang, Y. Liu, Z. Cao, Z. Zhang, F. Xu, and L. Sun

Abstract  

Polyaniline (PANI)/1-tetradecanol (TD) composite materials, a kind of novel composite that can conduct electricity and store thermal energy at the same time, thus possess the ability to endure certain heat shock, were prepared for the first time. FTIR and XRD results showed that there were some interactions existed between PANI and TD. The thermal stability of the composites exhibited both the characteristics of PANI and TD. The DSC experiments showed that the highest phase change enthalpy of the composites could be as 73% as that of TD, indicating it was a good form-stable phase change material. The thermal conductivity of the composites was also improved. The AC (Alternating Current) conductivity of the composites was enhanced to close to that of PANI when the mass fraction of PANI in the composite was increased to 46%. Heat shock experiments showed that the heat shock resistibility of the composite was greatly improved comparing to that of pure PANI.

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Abstract  

The thermal decomposition of strontium acetate hemihydrate has been studied by TG-DTA/DSC and TG coupled with Fourier transform infrared spectroscopy (FTIR) under non-isothermal conditions in nitrogen gas from ambient temperature to 600°C. The TG-DTA/DSC experiments indicate the decomposition goes mainly through two steps: the dehydration and the subsequent decomposition of anhydrous strontium acetate into strontium carbonate. TG-FTIR analysis of the evolved products from the non-oxidative thermal degradation indicates mainly the release of water, acetone and carbon dioxide. The model-free isoconversional methods are employed to calculate the E a of both steps at different conversion α from 0.1 to 0.9 with increment of 0.05. The relative constant apparent E a values during dehydration (0.5<α<0.9) of strontium acetate hemihydrate and decomposition of anhydrous strontium acetate (0.5<α<0.9) suggest that the simplex reactions involved in the corresponding thermal events. The most probable kinetic models during dehydration and decomposition have been estimated by means of the master plots method.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: L. Cao, J. Hattrick-Simpers, R. Bindel, B. Tomlin, R. Zeisler, R. Paul, L. Bendersky, and R. Downing

Abstract  

Cold neutron prompt gamma activation analysis (PGAA) was used to determine the mass of hydrogen in Mg hydride thin films with varying hydrogenation times. The results suggest that hydrogenation of the Mg thin films remains unsaturated even after 48 h of treatment, contrary to the indications of inferential hydrogen measurement methods. To demonstrate PGAA as an effective combinatorial methodology for hydride thin films, a continuously varying composition gradient of thin MgyTi(1−y) hydride film with y ranging from 0.65 to 0.94 was prepared and analyzed by both PGAA and instrumental neutron activation analysis (INAA). The variation in the molar ratio of Mg, Ti, and H was obtained for nine 5 mm wide segments of the film.

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