Novel poly(vinyl chloride) based thermoplastic elastomers incorporating vinyl-functionalized silicone rubber

ABSTRACT

Novel poly(vinyl chloride) (PVC) based thermoplastic elastomers were developed by blending with different proportions of vinyl-functionalized silicone rubber. Scanning electron microscopy (SEM) confirmed good compatibility between PVC and silicone rubber which allowed enhancement of the stress-strain behavior. On the contrary to neat PVC, exposure to heat or UV radiation was found not to cause any considerable deterioration to the stress-strain behavior. Fourier Transform Infrared (FTIR) revealed a possible chemical interaction between the blend components involving the vinyl groups from the silicone rubber, which is thought to be the reason for maintaining the mechanical properties unaltered. Further investigation with ultraviolet-visible (UV-Vis.) spectroscopy signified absence of intensive dehydrochlorination usually encountered for PVC after exposure to heat or UV radiation, which indicates a potential stabilizing effect for the silicone rubber and build up of a network structure comprising both hard and soft segments.     

Chromatographic analysis of some drugs employed in erectile dysfunction therapy: Qualitative and quantitative studies using calixarene stationary phase

In this study, the effect of change in chromatographic process variables on the retention behavior of four drugs employed in erectile dysfunction therapy on a calixarene stationary phase is described. Three of these drugs are known to treat erectile dysfunction, namely, sildenafil citrate, tadalafil, and apomorphine hydrochloride, and one drug that is used as opioid analgesic, tramadol hydrochloride, which is quiet widely misused to treat premature ejaculation. The results indicate the importance of considering the structure and pK_a values of drugs to be separated along with mobile phase composition. A new optimized, rapid, and accurate liquid chromatography method is also established for simultaneous determination of sildenafil citrate, tadalafil, and apomorphine hydrochloride in pharmaceutical preparations and bulk powders. The chromatographic separation of the three pharmaceuticals was achieved on a calixarene column in less than 10 min using a binary mobile phase of 35% acetonitrile and 65% 50 mM sodium perchlorate pH2.5 at 1 mL/min flow rate. The method was validated for system efficiency, linearity, accuracy, precision, limits of detection and quantitation, specificity, stability, and robustness. Statistical analysis proved that the method enabled reproducible and selective quantification of all three analytes in bulk drugs and in pharmaceutical preparations.     

(+)-Apollineanin: a new flavanone from Tephrosia apollinea

Chemical investigation of the leaves of Tephrosia apollinea has yielded a new flavanone named (+)-apollineanin, together with two known flavones: (-)-semiglabrin and (-)-semiglabrinol. The structure of the new compound was determined on the basis of mass, 1D and 2D NMR spectroscopies including NOE difference spectroscopy. The absolute stereochemistry of (+)-apollineanin was determined by Mosher ester methodology and from CD data.     

Thiazolidinedione Derivatives: In Silico,In Vitro,In Vivo,Antioxidant and Anti-Diabetic Evaluation

This work aimed to synthesize a new antihyperglycemic thiazolidinedione based on the spectral data. The DFT\B3LYP\6-311G** level of theory was used to investigate the frontier molecular orbitals (FMOs), chemical reactivity and map the molecular electrostatic potentials (MEPs) to explain how the synthesized compounds interacted with the receptor. The molecular docking simulations into the active sites of PPAR-γ and α-amylase were performed. The in vitro potency of these compounds via α-amylase and radical scavenging were evaluated. The data revealed that compounds (4–6) have higher potency than the reference drugs. The anti-diabetic and anti-hyperlipidemic activities for thiazolidine-2,4-dione have been investigated in vivo using the alloxan-induced diabetic rat model along with the 30 days of treatment protocol. The investigated compounds didn’t show obvious reduction of blood glucose during pre-treatments compared to diabetic control, while after 30 days of treatments, the blood glucose level was lower than that of the diabetic control. Compounds (4–7) were able to regulate hyperlipidemia levels (cholesterol, triglyceride, high-density lipoproteins and low- and very-low-density lipoproteins) to nearly normal value at the 30th day.     

HypoGel负载Pd纳米催化剂制备与表征及温和条件下催化Suzuki反应(英文)

A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoG el resin has been prepared in the absence of any ligands using an extensive cross-linking method.This newly developed nanocatalyst was characterized by N_2 adsorption-desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX),Fourier transform infrared spectroscopy and inductively coupled plasma-mass spectrometer(ICP-MS)techniques.TEM and XRD results revealed that the Pd nanoparticles were well dispersed with diameters in the range of 4–12 nm,and an average size of about 8 nm.The cross-linked Pd catalyst demonstrated excellent catalytic activity towards the synthesis of a series of biaryl compounds by the reaction of various aryl halides(e.g.,bromides andiodides)with phenylboronic acid in the presence of tetrabutylammonium bromide.ICP-MS analysis indicated that there was only 0.25%weight loss of Pd(0.55±0.02 ppm)from the supported catalyst after the first cycle reaction.Furthermore,the catalyst showed excellent reusability(up to five uses)with consistently high levels of catalytic activity following its recovery by filtration.     

Green Synthesis of Gold Nanoparticles Using Plant Extracts as Beneficial Prospect for Cancer Theranostics

Gold nanoparticles (AuNPs) have been widely explored and are well-known for their medical applications. Chemical and physical synthesis methods are a way to make AuNPs. In any case, the hunt for other more ecologically friendly and cost-effective large-scale technologies, such as environmentally friendly biological processes known as green synthesis, has been gaining interest by worldwide researchers. The international focus on green nanotechnology research has resulted in various nanomaterials being used in environmentally and physiologically acceptable applications. Several advantages over conventional physical and chemical synthesis (simple, one-step approach to synthesize, cost-effectiveness, energy efficiency, and biocompatibility) have drawn scientists’ attention to exploring the green synthesis of AuNPs by exploiting plants’ secondary metabolites. Biogenic approaches, mainly the plant-based synthesis of metal nanoparticles, have been chosen as the ideal strategy due to their environmental and in vivo safety, as well as their ease of synthesis. In this review, we reviewed the use of green synthesized AuNPs in the treatment of cancer by utilizing phytochemicals found in plant extracts. This article reviews plant-based methods for producing AuNPs, characterization methods of synthesized AuNPs, and discusses their physiochemical properties. This study also discusses recent breakthroughs and achievements in using green synthesized AuNPs in cancer treatment and different mechanisms of action, such as reactive oxygen species (ROS), mediated mitochondrial dysfunction and caspase activation, leading to apoptosis, etc., for their anticancer and cytotoxic effects. Understanding the mechanisms underlying AuNPs therapeutic efficacy will aid in developing personalized medicines and treatments for cancer as a potential cancer therapeutic strategy.     

Enhancing the pyrolysis of scrap rubber for carbon nanotubes/graphene production via chemical vapor deposition

Carbon nanostructures are considered nowadays as very important materials for both fundamental research and industrial applications because of their well-defined morphologies, which leads to excellent performance in various fields. This study presents the preparation of carbon nanostructures starting from cheap source represented by scrap rubber after pursuing optimized pyrolysis of scrap rubber at 500^oC as deduced from thermal gravimetric analysis (TGA). The resulting cracked hydrocarbons from pyrolysis were collected over a well-designed Fe-Ni-Cu/MgO as catalyst via chemical vapor deposition (CVD), in which a growth temperature of 750^oC was undertaken for 60 min. A further attempt was elaborated where the scrap rubber was exposed to thermal aging at 90^oC for 14 days prior to CVD of its pyrolysis products in order to enhance the cracking process and increase the yield of the lighter hydrocarbons produced which leads to formation of well-defined carbon nanostructures. Characterizations on the produced carbon nanostructures were achieved using transmission electron microscopy (TEM) and Raman spectroscopy. The adsorption of methylene blue on the carbon nanostructures was also studied. The characterizations confirmed that the morphology of the resulting carbon nanostructures derived from scrap rubber without prior thermal aging composed of graphene sheets wrapping carbon nanotubes (CNTs-A). After thermal aging of scrap rubber prior to pyrolysis and CVD, the produced carbon nanostructures composed principally of CNTs (CNTs-B) in a well-defined form in higher yield. The Langmuir model appeared to be best-fitting the adsorption of MB on both samples. High monolayer adsorption capacity of 95 mg MB/g was accomplished in case of CNTs-A versus 60 mg MB/g in case of CNTs-B, respectively. Ultraviolet-Visible (UV-Vis.) spectroscopic study revealed that the presence of MB molecules on the surface of CNTs may enhance the electronic properties of the prepared samples.     

MEH-PPV/Alq_3-based bulk heterojunction photodetector

In this paper, we present the effect of varied illumination levels on the electrical properties of the organic blend bulk heterojuction （BHJ） photodiode. To prepare the BHJ blend, poly（2-methoxy-5（2P-ethylhexyloxy） phenyleneviny- lene （MEH-PPV） and aluminum-tris-（8-hydroxyquinoline） （Alq3） are used as donor and acceptor materials, respectively. In order to fabricate the photodiode, a 40-nm thick film of poly（3, 4-ethylendioxytbiophene）：poly（styrensulfonate） （PE- DOT：PSS） is primarily deposited on a cleaned ITO coated glass substrate by spin coating technique. The organic photo- sensitive blend is later spun coated on the PEDOT：PSS layer, followed by the lithium fluoride （LiF） and aluminium （A1） thin films deposition by thermal evaporation. The optical properties of the MEH-PPV：Alq3 blend thin films are investigated using photoluminescence （PL） and UV-Vis spectroscopy. The photodiode shows good photo-current response as a function of variable illumination levels. The responsivity value - 8 mA/W at 3 V is found and the ratio of photo-current to dark current （lph/IDark） is found to be 1.24.     

Acylphosphonamidates and α-hydroxyiminophosphonamidates. Synthesis of N-acylphosphordiamidates by Beckmann rearrangement. Crystal structure of (E)-α-hydroxyiminobenzyl-1-pyrrolidinylphosphinate

Reaction of methyl benzoylphosphonochloridate (3) with a secondary or primary series of amines yielded methyl benzoylphosphonamidates, 4a-e. The latter compounds reacted with hydroxylamine to yield a-hydroxyiminobenzylphosphonamidates (5a-e), largely as (E)-isomers. The structure of methyl (E)-a-hydroxyimino-benzyl-1-pyrrolidinylphosphinate (5b) was determined by single-crystal X-ray crystallography. Heating oximes 5a-e in boiling toluene caused them to undergo Beckmann rearrangement to N-benzoylphosphordiamidates 6a-e. © 1996 John Wiley & Sons, Inc.