Irradiation of ultrahigh-molecular-weight polyethylene

An ultrahigh-molecular-weight polyethylene material covering a range of crystallinity from 42 to 79% increased in calorimetric crystallinity as a result of chain scission following ionizing irradiation. Carbonyl was formed by a diffusion-limited reaction of oxygen with long-lived free radicals. Trans-vinylene production was linear with radiation dose and was highest for the sample of highest crystallinity but was not sensitive to environment.     

Synergetic extraction and spectrophotometric determination of gold(III)

Summary A method is described for the synergetic extraction and subsequent spectrophotometric determination of gold(III). The gold--furil dioxime-pyridine complex extracted into chloroform has a characteristic yellow colour with an absorption maximum at 330 nm. Beer's law is obeyed in the concentration range [Au(III)]45g/ 10 ml organic phase. A scheme to separate gold from interfering elements by extraction with 4-methyl-2-pentanol in benzene has been proposed.

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Zusammenfassung Ein Verfahren zur synergetischen Extraktion und nachfolgenden spektrophotometrischen Bestimmung von Gold(III) wurde beschrieben. Die Komplexverbindung des Goldes mit-Furildioxim und Pyridin ist in chloroformischer Lösung gelb gefärbt. Ihr Absorptionsmaximum liegt bei 330 nm. Bis 45g Au(III)/10 ml organischer Phase wird das Beersche Gesetz befolgt. Die Trennung des Goldes von störenden Elementen durch Extraktion mit 4-Methyl-2-pentanol in Benzol wurde vorgeschlagen.

     

镉取代对纳米镍铁氧体结构和磁性的影响

采用湿化学共沉淀法合成了Ni_1-xCd_xFe₂O₄ (0≤x≤0.5)的混合铁氧体,利用X射线衍射对其结构和晶相进行表征．结果表明：随着镉Cd浓度的增加晶格参数逐渐增大．扫描电子显微镜研究微观结构,TG/DTA研究了硫酸共沉淀物．揭示了在650 oC合成铁氧体同时进行分解．测量了纳米粒子的磁化强度和交流磁化率．结果表明,Ni_1-xCd_xFe₂O₄混合铁氧体的磁化率、居里温度和有效磁矩随着镉含量的增加下降。     

Major volatile constituents of Annona squamosa L. bark

The volatile constituents of Annona squamosa L. bark were identified from the essential oil obtained by steam distillation and studied by GC/MS. Six major components were identified as 1H-Cycloprop(e)azulene (3.46%), germacrene D (11.44%), bisabolene (4.48%), caryophyllene oxide (29.38%), bisabolene epoxide (3.64%) and kaur-16-ene (19.13%). The oil was also screened for its antimicrobial activity, which exhibited a significant antimicrobial activity against Bacillus subtilis and Staphylococcus aureus.     

Magnetic properties of rare earth ion (Sm) added nanocrystalline Mg-Cd ferrites, prepared by oxalate co-precipitation method

Nanocrystalline ferrite powder having the general formula Mg_1−xCd_xFe₂O₄+5% Sm³⁺ (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) was synthesized by chemical oxalate co-precipitation technique. The synthesized powder was characterized by X-ray, IR and SEM techniques. The XRD analysis confirms cubic spinel phase with orthoferrite secondary phase. The lattice constant increases with increase in Cd²⁺ content (x). It is smaller than that for pure Mg-Cd ferrites. The average crystallite size lies in the range 28.69-32.66 nm. Saturation magnetization and magnetic moment increase with cadmium content up to x=0.4 and decrease thereafter. This is attributed to the existence of localized canted spin. The decrease in saturation magnetization and magnetic moment beyond x=0.4 is due to the presence of triangular spin arrangement on B-site. Coercivity and remanent magnetization decrease while Y-K angles increase with Cd²⁺ content. The Sm³⁺ addition improves the magnetic properties.     

Deposition of copper iodide thin films by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) methods

In this paper, we report structural, morphological, electrical studies of copper iodide (CuI) thin films deposited onto glass substrates by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) methods. CuI thin films were characterized for their structural, morphological and wettability studies by means of X-ray diffraction (XRD), FT-Raman spectroscopy, scanning electron microscopy (SEM), optical absorption, and contact angle measurement methods. Thickness of thin films was 1 ± 0.1 μm measured by gravimetric weight difference method. The CuI thin films were nanocrystalline, with average crystal size of ～60 nm. The FT-IR study confirmed the formation of CuI on the substrate surface. SEM images revealed the compact and cube like structure for CuI thin films deposited by CBD and SILAR methods, respectively. Optical absorption study revealed optical energy gaps as 2.3 and 3.0 eV for CBD and SILAR methods, respectively. Wettability study indicated that CuI thin films deposited by SILAR method are more hydrophobic as compared to CBD method.     

Cation disorder and structural studies on Bi4−x Nd x Ti3O12 (0.0≤x≤2.0)

Here we report the results of combined powder X-ray and neutron diffraction studies of Bi_4?x Nd _x Ti₃O₁₂ (0.0 ≤ x ≤ 2.0) compositions. The parent Bi₄Ti₃O₁₂ has an orthorhombic lattice (space group: B2cb) with unit cell parameters a = 5.4432(5) Å, b = 5.4099(5) Å and c = 32.821(2) Å, and V = 966.5(1) ų. This orthorhombic lattice is retained in all the studied compositions. The unit cell parameters gradually decrease with Nd³⁺ ion concentration with a discontinuity at x = 0.75. Orthorhombicity of the lattice decreases with increase in Nd³⁺ content in the lattice. The orthorhombic unit cell parameters for a representative Bi₂Nd₂Ti₃O₁₂ composition are: a = 5.3834(9), b = 5.3846(9) and c = 32.784(1) Å. The observed orthorhombic distortion at x = 2.0 is very small and thus the crystal structure apparently has a pseudo-tetragonal lattice. In addition, Nd³⁺ preferentially substitutes in the perovskite slab of the Aurivillius structure. The fraction of Nd³⁺ in the fluorite slab increases with increase in Nd³⁺ contents.     

Gold(I)/Chiral Brønsted Acid Catalyzed Enantioselective Hydroamination–Hydroarylation of Alkynes: The Effect of a Remote Hydroxyl Group on the Reactivity and Enantioselectivity

The catalytic enantioselective hydroamination–hydroarylation of alkynes under the catalysis of (R₃P)AuMe/(S)‐3,3′‐bis(2,4,6‐triisopropylphenyl)‐1,1′‐binaphthyl‐2,2′‐diyl hydrogenphosphate ((S)‐TRIP) is reported. The alkyne was reacted with a range of pyrrole‐based aromatic amines to give pyrrole‐embedded aza‐heterocyclic scaffolds bearing a quaternary carbon center. The presence of a hydroxyl group in the alkyne tether turned out to be very crucial for obtaining products in high yields and enantioselectivities. The mechanism of enantioinduction was established by carefully performing experimental and computational studies.