On the tangential stress anomaly in the displacement discontinuity method

It is shown that the anomaly associated with the incorrect evaluation of tangential stresses in the displacement discontinuity (DD) method, commonly used to solve crack problems, is related to the order of singularity of the fundamental solutions of linear elasticity. It is established here that a minimum of linear variation of the shear DD distribution is needed to obtain the correct tangential stress jump across a crack. Alternatively, a correction term (‘patch’) that improves tangential stresses is derived. It is also shown that need for higher functionality is a fundamental requirement rather than a convenient artifice for obtaining better accuracy.     

Influence of substrate temperature on the properties of vacuum evaporated InSb films

Indium Antimonide (InSb) thin films were grown onto well cleaned glass substrates at different substrate temperatures (303, 373 and 473 K) by vacuum evaporation. The elemental composition of the deposited InSb film was found to be 52.9% (In) and 47.1% (Sb). X‐ray diffraction studies confirm the polycrystallinity of the films and the films show preferential orientation along the (111) plane. The particle size (D), dislocation density (δ) and strain (ε) were evaluated. The particle size increases with the increase of substrate temperature, which was found to be in the range from 22.36 to 32.59 nm. In Laser Raman study, the presence of longitudinal mode (LO) confirms that the deposited films were having the crystalline nature. Raman peak located at 191.26 cm^–1 shift towards the lower frequencies and narrows with increase in deposition temperature. This indicates that the crystallinity is improved in the films deposited at higher substrate temperatures. Hall measurements indicate that the films were p‐type, having carrier concentration ≅10¹⁶ cm^–3 and mobility (4–7.7) ×10³ cm²/Vs. It is observed that the carrier concentration (N) decreases and the Hall mobility (μ) increases with the increase of substrate temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A New Spray Reagent for Detection and Differentiation of Sulfur Compounds in Plant Extracts

JPC – Journal of Planar Chromatography – Modern TLC -     

1‐(2,5‐Di­chloro­phenyl)‐3‐methyl‐5‐phenyl‐1H‐pyrazole

The title compound, C₁₆H₁₂Cl₂N₂, crystallizes in the centrosymmetric space group P2₁/c. Two independent but chemically identical mol­ecules comprise the asymmetric unit and in each of these the pyrazole ring is planar.     

Synthesis and conductivity of poly acene quinone radical polymers

Polymers with conductivities from 8.6 × 10⁰ to 7.3 × 10^?6 (ω cm)^?1 at 2–12 kbar were prepared by zinc-chloride-catalyzed condensation of polycyclic aromatic hydrocarbons, heterocycles, and quinones with pyromellitic dianhydride, tetrabromophthalic anhydride, and tetrachlorophthalic anhydride at 450°C. These materials are stable in air and exhibit strong electroactive character without addition of oxidizing or reducing agents (dopants).     

Crystallographic report: (2,2′‐Bipyridyl)bis(ethanoldithiocarbamato)zinc(II)

Zn(meadtc)₂(2,2′‐bipy) is a ZnS₃N₂ chromophore with a distorted square pyramidal geometry. The IR band at 1002 cm^?1 and the bond valence sum value of 1.98 confirmed the monodentate dithiocarbamate in coordination. The non‐bonding Zn–S distance is 5.004(3) Å. Copyright © 2004 John Wiley & Sons, Ltd.     

DFT/TD-DFT study on halogen doping and solvent contributions to the structural and optoelectronic properties of poly[3,6-carbazole] and poly[indolo(3,2-b)-carbazole]

The polycarbazoles have been proved to be a good organic semiconductor. These are investigated by quantum chemical studies using B3LYP density functional theory (DFT), and the studies have given a detailed understanding on the impact of carbazole units and an introduction to the electron donating on the optoelectronic properties. The electron withdrawing groups of halogen atoms (chlorine, bromine and iodine) have been substituted into the side chain of the poly[3,6-carbazoles] (PCs) and poly[indolo(3,2-b)-carbazoles] (PICs) and analysed. The band was assigned in the gas phase at 354.8 and 365.1 nm for PCs and PICs which are in good agreement with experimental values of 350 and 390 nm. The calculated results show that the selected three halogen derivatives exhibit a strong blue shift in the toluene solvent medium, with high electronic transition. It is found that PCs, PICs and their derivatives have a narrow band derived in the conduction band, and it is composed of 3p, 4p and 5p states; thus, the energy gap of PCs and PICs increased between the highest occupied molecular orbital and lowest unoccupied molecular orbital energy level by the addition of electron acceptor group atoms. The doped PC and PIC electronegativities are well plotted by an electrostatic potential map, and the plot reveals that chlorine-doped PCs and PICs have less electronegativity and bromine-doped polymer has high electronegativity than that of the chlorine-doped polymers. The results obtained from these studies will expose the affairs between the molecular geometry and electronic and optical properties of the investigated polymers.     

Arthrichitin. A New Cell Wall Active Metabolite from Arthrinium phaeospermum

Arthrichitin (1), C(33)H(46)N(4)O(9), is a new cell wall active depsipeptide isolated from the fermentation broth of Arthrinium phaeospermum (HIL Y-903022). Its structure was elucidated on the basis of spectroscopic and chemical degradation studies. Arthrichitin consists of serine, beta-keto tryptophan, glutamic acid, and 2,4-dimethyl-3-hydroxydodecanoic acid units.     

N‐(2‐Hydroxyethyl)‐N‐methyldithiocarbamato Complexes of Nickel(II) with Phosphorus Donor Ligands

Planar nickel(II) complexes involving N‐(2‐Hydroxyethyl)‐N‐methyldithiocarbamate, such as [NiX(nmedtc)(PPh₃)] (X = Cl, NCS; PPh₃ = triphenylphosphine), and [Ni(nmedtc)(P‐P)]ClO₄(P‐P = 1,1‐bis(diphenylphosphino)methane(dppm); 1,3‐bis(diphenylphosphino)propane (1,3‐dppp); 1,4‐bis(diphenylphosphino)butane(1,4‐dppb) have been synthesized. The complexes have been characterized by elemental analyses, IR and electronic spectroscopies. The increased νC–N value in all the complexes is due to the mesomeric drift of electrons from the dithiocarbamate ligands to the metal atom. Single crystal X‐ray structure of [Ni(nmedtc)(1,3‐dppp)]ClO₄·H₂O is reported. In the present 1,3‐dppp chelate, the P–Ni–P angle is higher than that found in 1,2‐bis(diphenylphosphino)ethane‐nickel chelates and lower than 1,4‐bis(diphenylphosphino)butane‐nickel chelates, as a result of presence of the flexible propyl back bone connecting the two phosphorus atoms of the complex.