Mechanical properties and degradation studies of poly(D,L‐lactide‐co‐glycolide) 50:50/graphene oxide nanocomposite films

Poly(D,L‐lactide‐co‐glycolide) 50:50 (PLGA)/graphene oxide (GO) nanocomposite films were prepared with various GO weight fractions. A significant enhancement of mechanical properties of the PLGA/GO nanocomposite films was obtained with GO weight fractions. The incorporation of only 5 wt% of GO resulted in an ~2.5‐fold and ~4.7‐fold increase in the tensile strength and Young's modulus of PLGA, respectively. The thermomechanical behaviors of composite films were investigated by dynamic mechanical analysis. Results indicated that the values of T_g and storage moduli of the PLGA/GO composites were higher than those of the pristine PLGA. The improvement in oxygen barrier properties of composites was presumably attributed to the filler effect of the randomly dispersed GO throughout the PLGA matrix. In this work, we also studied in vitro biodegradation behavior. PLGA/GO composite films were hydrolyzed at 37°C for periods up to 49 days. Because of the presence of GO nanosheets, degradation of composite films took place more slowly with increasing GO amounts. Copyright © 2013 John Wiley & Sons, Ltd.     

Knockdown of 14-3-3ζ enhances radiosensitivity and radio-induced apoptosis in CD133+ liver cancer stem cells

14-3-3ζ is related to many cancer survival cellular processes. In a previous study, we showed that silencing 14-3-3ζ decreases the resistance of hepatocellular carcinoma (HCC) to chemotherapy. In this study, we investigated whether silencing 14-3-3ζ affects the radioresistance of cancer stem-like cells (CSCs) in HCC. Knockdown of 14-3-3ζ decreased cell viability and the number of spheres by reducing radioresistance in CSCs after γ-irradiation (IR). Furthermore, the levels of pro-apoptotic proteins were upregulated in CSCs via silencing 14-3-3ζ after IR. These results suggest that 14-3-3ζ knockdown enhances radio-induced apoptosis by reducing radioresistance in liver CSCs.     

Low temperature synthesis and luminescence investigations of YAG:Ce,Eu nanocomposite powder for warm white light-emitting diode

The preparation of the cerium and europium co-doped YAG materials as well as the study for their synthesis and emitting mechanism of the energy transfer between Ce³⁺ and Eu³⁺ were investigated in the present study. YAG:Ce³⁺, Eu³⁺ powders were synthesized using a high-energy ball milling method in different sintering temperature and atmosphere: air and H₂/N₂. The effects of the synthesis procedure on the crystallinity, morphology, structure, and luminescence spectra were examined by X-ray diffraction, field emission-scanning electron microscopy, and photoluminescence spectroscopy. The europium co-doped YAG:Ce³⁺ phosphors is improved the chromaticity coordinates.     

Synthesis and biological screening of some chromonyl-substituted heterocycles derived from 2(3H)-furanone derivative

A 2(3H)-furanone bearing chromonyl moiety at position-3 was synthesized and utilized for the construction of N-heterocycles such as pyrrolone, N-aminoquinolone, and pyridazinone derivatives. The reactivity of the chromonylfuranone toward some nitrogen nucleophiles such as ammonia, benzylamine, hydrazine, and phenylhydrazine was studied. On the other hand, thiation of the starting chromonylfuranone interestingly provides mono- and di-thiated products. The chemoselectivity of these reactions is discussed. The structures of all products obtained were elucidated from their analytical and spectral data. The antimicrobial activities of selected examples of the synthesized compounds were examined against two strains of bacteria and two fungus strains. Some of them showed promising antimicrobial activities.     

Synthesis of Some New Azoloazines with Potent Anti‐inflammatory and Analgesic Activity

Starting from pyrimidine‐2‐thiones, a set of new fused triazoles, thiazoles, and thiazines has been obtained. The mechanistic pathway and structures of all the novel products were ascertained on the foundation of spectral information and elemental analyses. The analgesic and anti‐inflammatory activities of all the prepared compounds were predestined. The outcomes disclosed that all of the examined samples revealed potent activity. Moreover, the relation between the structure and the activity has been researched.     

An efficient method for the synthesis of gem-difluoroolefins

A series of gem-difluoroolefin derivatives were synthesized in moderate to good yields by the reaction of α,α-difluoro-β-carbonyl benzothiazol-2-yl sulfones (DFBTs) with various carbon nucleophiles. Using dl-proline as organocatalyst, the reaction of DFBT with acetone gave a tertiary alcohol, which could be further converted to the corresponding difluoroolefin by LDA.     

Ultrasonic encapsulation – A review

Encapsulation of materials in particles dispersed in water has many applications in nutritional foods, imaging, energy production and therapeutic/diagnostic medicine. Ultrasonic technology has been proven effective at creating encapsulating particles and droplets with specific physical and functional properties. Examples include highly stable emulsions, functional polymeric particles with environmental sensitivity, and microspheres for encapsulating drugs for targeted delivery. This article provides an overview of the primary mechanisms arising from ultrasonics responsible for the formation of these materials, highlighting examples that show promise particularly in the development of foods and bioproducts.     

A new procedure for determination of nickel in some fake jewelry and cosmetics samples after dispersive liquid–liquid microextraction by FAAS

A new, simple and cheap dispersive liquid–liquid microextraction (DLLME) procedure was optimized for the preconcentration of trace amounts of Ni(II) as a prior step to its determination by flame atomic absorption spectrometry (FAAS). It is based on the microextraction of nickel, where appropriate amounts of the extraction solvent (CHCl₃), disperser solvent (ethanol) and chelating agent, name 5‐[(Z)‐isoxazol‐3‐yl‐diazenyl]‐2‐methyl‐quinolin‐8‐ol (MMD), were firstly synthesized/characterized and used. Various parameters that affect the extraction procedure such as pH, centrifugation rate and time, the chelating agent (MMD) concentration and sampling volume on the recovery of Ni(II) were investigated. The preconcentration of a 20 ml sample solution was thus enhanced by a factor of 80. The resulting calibration graph was linear in the range of 0.24–10 mg L⁻¹ with a correlation coefficient of 0.9998. The limit of detection (3 s/b) obtained under optimal conditions was 1.00 μg L⁻¹. The relative standard deviation for certified reference material determinations was 1.2%. The accuracy of the method was verified by the determination of Ni(II) in the certified reference material of wastewater (Waste water CWW TMD). The proposed procedure was successfully applied to the determination of Ni(II) in some fake jewelry and cosmetics samples.