排序方式: 共有126条查询结果,搜索用时 15 毫秒
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Jaweria Ambreen Jinxian Yang Xiaodong Ye Mohammad Siddiq 《Colloid and polymer science》2013,291(4):919-925
The temperature-induced phase transition of poly(2-ethyl-2-oxazoline) (PEtOx) aqueous solution under mixing with a series of small carboxylic acids has been studied by turbidity measurements and laser light scattering. It has been found that cloud point temperature (T cp) of the PEtOx was changed to varying degrees depending upon the pH, ionic strength, molar ratio of acids to 2-ethyl-2-oxazoline unit, and carbon chain length of small carboxylic acids. Significant change in T cp was observed in the case of hexanoic acid. At acidic pH, an increase in the molar ratio of hexanoic acid to the 2-ethyl-2-oxazoline unit gradually decreased the phase transition temperature of the polymer as compared to the T cp of pure PEtOx. At original pH 6 (pH?>?pK a), T cp shifts to higher value than that of pure PEtOx for lower molar ratios and decreased later on with increasing the molar ratio. The shift in the T cp is described based on the differences in the driving force of phase transition, including hydrogen bonding between small carboxylic acids and PEtOx polymer and hydrophobic interaction. 相似文献
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Liangpo Liu Tongwei Xia Xueqin Zhang Dana Boyd Barr Ambreen Alamdar Jie Zhang Meiping Tian Qingyu Huang Heqing Shen 《Analytical and bioanalytical chemistry》2014,406(20):5049-5054
Infant exposure to endocrine disruptors (EDs) may cause adverse health effects because of their fast growth and development during this life stage. However, collecting urine from infants for exposure assessment using biological monitoring is not an easy task. For this purpose, we evaluated the feasibility of using urine expressed from disposable gel absorbent diapers (GADs) as a matrix for biomonitoring selected phenolic EDs. GADs urine was expressed with the assistance of CaCl2 and was collected using a device fabricated in our laboratory. The analytes were extracted and concentrated using a liquid-liquid method and their hydroxyl groups were modified by dansyl chloride to enhance their chromatography and detection. Finally, the analytes were measured by high-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). The target chemicals were bisphenol A, triclosan, 17 α-ethynylestradiol, the natural hormone estrone, and 17 β-estradiol. The ratio of the CaCl2 to the urine-wetted gel absorbent, variation of the inter-urination volume, and analyte deposition bias in the diaper were assessed. Analyte blank values in the diapers, the sample storage stabilities, and recoveries of the analytes were also evaluated. The results showed that 70–80 % of the urine could be expressed from the diaper with the assistance of CaCl2 and 70.5–124 % of the spiked analytes can be recovered in the expressed urine. The limits of detections (LODs) were 0.02–0.27 ng/mL, well within the range for detection in human populations. Our pilot data suggest that infants are widely exposed to the selected EDs. 相似文献
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Nada Abdullah Yahya Tamimi Sergey Dobretsov Najwa Al Balushi Jalila Alshekaili Hamed Al Balushi Mahmood Al Kindi Syed Imran Hassan Shadia Al Bahlani Benjamin K. Tsang Ikram A. Burney 《Molecules (Basel, Switzerland)》2021,26(12)
High-grade epithelial ovarian cancer is a fatal disease in women frequently associated with drug resistance and poor outcomes. We previously demonstrated that a marine-derived compound MalforminA1 (MA1) was cytotoxic for the breast cancer cell line MCF-7. In this study, we aimed to examine the effect of MA1 on human ovarian cancer cells. The potential cytotoxicity of MA1was tested on cisplatin-sensitive (A2780S) and cisplatin-resistant (A2780CP) ovarian cancer cell lines using AlamarBlue assay, Hoechst dye, flow cytometry, Western blot, and RT-qPCR. MA1 had higher cytotoxic activity on A2780S (IC50 = 0.23 µM) and A2780CP (IC50 = 0.34 µM) cell lines when compared to cisplatin (IC50 = 31.4 µM and 76.9 µM, respectively). Flow cytometry analysis confirmed the cytotoxic effect of MA1. The synergistic effect of the two drugs was obvious, since only 13% of A2780S and 7% of A2780CP cells remained alive after 24 h of treatment with both MA1 and cisplatin. Moreover, we examined the expression of bcl2, p53, caspase3/9 genes at RNA and protein levels using RT-qPCR and Western blot, respectively, to figure out the cell death mechanism induced by MA1. A significant down-regulation in bcl2 and p53 genes was observed in treated cells compared to non-treated cells (p < 0.05), suggesting that MA1 may not follow the canonical pathway to induce apoptosis in ovarian cancer cell lines. MalforminA1 showed promising anticancer activity by inducing cytotoxicity in cisplatin-sensitive and cisplatin-resistant cancer cell lines. Interestingly, a synergistic effect was observed when MA1 was combined with cisplatin, leading to it overcoming its resistance to cisplatin. 相似文献
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Majdoub Mohammed Essamlali Younes Amadine Othmane Ganetri Ikram Hafnaoui Anass Khouloud Mehdi Zahouily Mohamed 《Cellulose (London, England)》2021,28(12):7717-7734
Cellulose - A novel, environmentally friendly and simple method for chemical functionalization of microcrystalline cellulose (MCC) to produce organophilic cellulose nanocrystals (CNC-ODA) is herein... 相似文献
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K. Pramoda Kota Moses Mohd. Ikram K. Vasu A. Govindaraj C. N. R. Rao 《Journal of Cluster Science》2014,25(1):173-188
Single-walled nanohorns (SWNHs) have been prepared by sub-merged arc discharge of graphite electrodes in liquid nitrogen. The samples were examined by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Nitrogen and boron doped SWNHs have been prepared by the sub-merged arc discharge method using melamine and elemental boron as precursors. Intensification of Raman D-band and stiffening of G-band has been observed in the doped samples. The electrical resistance of the SWNHs varies in opposite directions with nitrogen and boron doping. Functionalization of SWNHs through amidation has been carried out for solubilizing them in non-polar solvents. Water-soluble SWNHs have been produced by acid treatment and non-covalent functionalization with a coronene salt. SWNHs have been decorated with nanoparticles of Au, Ag and Pt. Interaction of electron donor (tetrathiafulvalene, TTF) and acceptor molecules (tetracyanoethylene, TCNE) with SWNHs has been investigated by Raman spectroscopy. Progressive softening and stiffening of Raman G-band has been observed respectively with increase in the concentration of TTF and TCNE. 相似文献
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The present work is concerned with the synthesis and coordination compounds of 2-amino-N(2-aminobezoyl) benzohydrazide (ABH). The ligand was synthesized by the reaction of methylanthranilate and hydrazine in 2:1
molar ratio. It can be viewed as a modified form of hydrazide. The ligand was characterized by 1H-NMR, 13C-NMR, mass spectrometry, elemental analysis, and infrared studies. The ligand has got -NH2 moeity, the site for chelation. The complexes of Co(II), Ni(II), and Cu(II) chlorides and bromides were prepared. These complexes
were characterized by elemental analysis, infrared, conductance, and magnetic susceptibility studies. Infrared spectra studies
confirmed the formation of complexes, while elemental studies suggested the complexation of [M(ABH)X2] (where X = Cl− or Br−) composition. 相似文献
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Nazar Mohammad Ranjha Ikram Ullah Khan Shahzad Naseem 《Journal of Sol-Gel Science and Technology》2009,50(3):281-289
Flurbiprofen loaded PCL/PVP blend microspheres were prepared by o/w solvent evaporation method using various concentrations
of gelatin as emulsifying agent. Microsphere recovery decreased with a decrease in the concentration of the emulsifier in
the dispersion. Encapsulation efficiency and drug loading of microspheres increased with decrease in concentration of emulsifying
agent. Hydration rate, encapsulation efficiency and drug loading of microspheres increased with increase in concentration
of PVP. Rheological properties showed free flowing nature of microspheres. SEM (Scanning electron microscope) revealed microspheres
were discrete, spherical and became porous with decrease in concentration of emulsifying agent but smooth with higher concentration
of emulsifying agent. FTIR (Fourier transform infrared spectroscopy) spectra of pure and encapsulated flurbiprofen in all
formulation showed no significant difference in characteristic peaks, suggesting stability of flurbiprofen during encapsulation
process. X-RD (X-ray powder diffractometry) of pure flurbiprofen shows sharp peaks, which decreases on encapsulation, indicating
dispersion at molecular level and hence decrease in the crystallinity of drug in microspheres. Microspheres showed an enteric
nature at pH 1.2 and a sustained release pattern at pH 6.8. Rapid drug release was observed in microspheres with higher concentration
of PVP (polyvinylpyrrolidone), PVP acts as channeling agent. Formulation with low concentration of emulsifying agent also
showed a fast release due to porous structure. Drug release kinetics followed zero order at pH 1.2 while at pH 6.8 Higuchi
model was best fitted and was found non fickian. 相似文献