Interface,morphology, and the rheological properties of polymethylmethacrylate/impact modifier blends

Impact modifiers with grafted PMMA shell are used to modify polymethylmethacrylate matrix. The composition of the shell is chosen to enhance the interactions at the modifier/matrix interface and to obtain good dispersion of the impact modifier in order to optimize impact strength of the blend. The degree of interactions at the interface is characterized by the interfacial region where the chains of the matrix mix with those of the shell of the modifier. The deviation of the measured viscoelastic behavior of these blends from that predicted by the emulsion models has been attributed to the formation of the network structure due to the association of matrix chains with the shell of the modifier. It is expected that the network structure will decrease with increasing frequency and, as such, the effective volume of the particle is frequency dependent. This study uses the emulsion models to estimate the larger effective volume of the particle and, therefore, the extent of interaction at the interface. In the blends of this study it can be shown that at low modifier levels the solvent swelling of the modifier shell results in stronger interactions with the matrix; this effect is negated by the aggregation of particles at higher modifier loadings. The interaction of core modifier with the PMMA matrix seems to be similar to that of the core-shell modifier. This would not be expected from the calculated interfacial thickness of approximately 4 nm. It is, therefore, proposed that during melt-processing the core modifier surface was altered due to grafting of the matrix PMMA chains during melt-blending to (BA/St) copolymer of the core modifier thus reducing the interfacial tension. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2623–2634, 1998     

Chemical characterisation and hepatoprotective potential of Cosmos sulphureus Cav. and Cosmos bipinnatus Cav.

This study was conducted to validate the hepatoprotective activity of Cosmos sulphureus and Cosmos bipinnatus. Aqua-methanolic extracts of both plants were evaluated for the presence of various phyto-constituents through HPLC. Different doses of both plant extracts were administered to rats for nine days. Standard control was silymarin 100 mg/kg. Paracetamol 1 gm/kg was administered 3 h post treatment on 9th day for induction of hepatotoxicity. Blood was collected for the evaluation of liver biochemical markers and livers were removed for histopathological evaluation 24 h post-paracetamol treatment. HPLC analysis revealed the presence of quercetin, gallic acid, caffeic acid and chlorogenic acid in both plant extracts. The extracts of both plants decreased the level of alanine aminotransaminase and total bilirubin significantly (p < 0.05), dose dependently and protected hepatocytes from paracetamol-induced hepatotoxicity. It can be concluded that both plants may possess hepatoprotective activity possibly due to the presence of quercetin and phenolic compounds.     

The liquid—liquid extraction of platinum in the presence of tin(II) chloride from dilute hydrochloric acid into 4-methyl-2-pentanone

The distribution of complexes of type [Pt(SnCl₃)_nCl_4?n]^2? (n = 1–4) and [Pt(SnCl₃)₅]^3? between 1.5–3.5 M hydrochloric acid and 4-methyl-2-pentanone is discussed in detail. Platinum can be quantitatively extracted into the organic phase from hydrochloric acid solutions containing tin(II) chloride when the mole ratio Sn²⁺: Pt²⁺ > 5. In the presence of sufficient tin(II) chloride, the [Pt(SnCl₃)₅]^3? anion is the predominant species extracted into the organic phase. Similar results pertain to starting solutions of either Ptcl^2?₄ or PtCl^2?₆, although Pt⁴⁺ is rapidly reduced to Pt²⁺. Small amounts of Co²⁺, Ni²⁺, Fe³⁺ and Cu²⁺ do not interfere.     

Investigation of half-metallic ferromagnetism in hafnium and tantalum doped NiO for spintronic applications: A DFT study

Full Potential Linearised Augmented Plane Wave (FP-LAPW) method was used to investigate the electronic and magnetic properties of NiO doped with Hf and Ta within the frame work of density functional theory (DFT). NiO is found to be stable in rock salt structure. NiO shows conducting characteristics for the lattice constant of 4.155 Å. Doping Hf and Ta in the metallic super cell of NiO separately in the doping concentration of 12.5%, the compounds Hf_0.125Ni_0.875O and Ta_0.125Ni_0.875O are formed. These compounds of Hf_0.125Ni_0.875O and Ta_0.125Ni_0.875O are predicted to exhibit stability in the ferromagnetic phase. The density of states and band structure plots predict that these compounds exhibit half metallic character with formation of energy gap in one of the spins at the Fermi level. The total spin magnetic moments found in these compounds are 12.00689 μ_B and 10.97628 μ_B.     

Soccer-playing metal oxide giant spheres: a first step towards patterning structurally well defined nano-object collectives

In context with the challenge to assemble giant molecules into patterns with limited size, molybdenum oxide giant spheres (with a molecular mass of about 16 kDa) could be 'kicked out' like soccer balls into the gas phase using matrix assisted laser desorption and ionization (MALDI) and detected by TOF mass spectrometry while cluster collectives ranging from dimers to pentamers were observed.     

Phonetographic profiles and F0-SPL characteristics of untrained versus trained vocal groups

The phonetogram has been recommended as an international tool for voice analysis. However, the capability of this technique to distinguish between different vocal groups has not been clearly established. The purpose of this study was to examine untrained versus trained vocalists using the phonetogram and the fundamental frequency by intensity (F₀/SPL) information derived through that method. In this study, “musical” or “controlled” ranges of phonation were stressed rather than “physiological” ranges. Results indicated that (a) characteristic phonetographic profiles may be established for untrained versus trained vocalists, and (b) trained vocalists show significantly increased capability in terms of F₀ range and maximum, minimum, and comfortable SPL production. Elicitation of “controlled” phonations may be the key to revealing the underlying vocal capabilities of seemingly different vocal groups.     

Curative Effect of Catechin Isolated from Elaeagnus Umbellata Thunb. Berries for Diabetes and Related Complications in Streptozotocin-Induced Diabetic Rats Model

In this study, catechin (CTN) isolated from Elaeagnus umbellata was evaluated for in vitro antioxidant potential and inhibition of carbohydrate digestive enzymes (α-amylase and α-glucosidase). The compound was also tested for its in vivo antidiabetic potential using Sprague-Dawley rats as experimental animals. The effects of various doses of catechin in STZ (Streptozotocin) induced diabetic rats on fasting blood glucose level, body weight, lipid parameters, hepatic enzymes, and renal functions were evaluated using the reported protocols. The CTN exhibited the highest percent antioxidant for free radical scavenging activity against DPPH and ABTS free radicals, and inhibited the activity of carbohydrate digestive enzymes (with percent inhibition values: 79 ± 1.5% α-amylase and 80 ± 1.1% α-glucosidase). Administration CTN and standard glibenclamide significantly decreased the fasting blood glucose level and increased the body weight in STZ-induced diabetic rats. CTN significantly decreased the different lipid parameters, hepatic, and renal function enzyme levels along with Hb1c level in diabetic rats, while significantly increasing the high-density lipoprotein (HDL) level with values comparable to the standard glibenclamide. Further, the altered levels of glutathione and lipid peroxides of liver and kidney tissues were restored (by CTN) to levels similar to the control group. CTN significantly increased the antioxidant enzyme activities, total content of reduced glutathione, and reduced the malondialdehyde (MDA) level in rat liver and kidney tissues homogenates, and also corrected the histopathological abnormalities, suggesting its antioxidant potential.