Influence of Ball Burnishing Process on Equal Channel Angular Pressed Mg-Zn-Si Alloy on the Evolution of Microstructure and Corrosion Properties

Silicon - In the present study, Mg-4Zn-1Si alloy was subjected to equal channel angular pressing (ECAP) up to 4 passes at 300 °C, followed by ball burnishing using 0.3 mm...     

Harnessing “Click”‐Type Chemistry for the Preparation of Novel Electronic Materials

Sequence‐independent or “click”‐type chemistry is applied for the preparation of novel π‐conjugated oligomers. A variety of bi‐functional monomers for Wittig–Horner olefination are developed and applied in a sequential protection–deprotection process for the preparation of structurally similar π‐conjugated oligomers. Selected oligomers are incorporated as the organic semiconductors in light‐emitting diodes and a field‐effect transistor, demonstrating the potential of the approach.     

Shigella and the fluorinated quinolones

An 8-year-old girl presented with marked shortening of the right forearm due to destruction of both the radius and ulna secondary to neonatal osteomyelitis. A one-bone forearm operation was performed to achieve a stable forearm. Two years later, the one-bone forearm was lengthened for 6 months by callus distraction (callotasis) achieving 12 cm of extra length. The patient was last followed up at the age of 16. The appearance and functional outcome of the right upper limb had been improved and she was independent in all activities of daily living.     

Performance of 1REC-MHPM in the presence of adjacent channelinterference

The effect of adjacent channel interference (ACI) on the error probability of the rectangular frequency pulse multi-h phase-coded modulation (1REC-MHPM) is studied. Evaluations through simulation were done for different values of the absolute adjacent channel frequency spacing |Δf|, different time delay τ between the main channel and the interfering channel, and schemes with different number of modulation indexes. It is found that ACI effects can only be eliminated when |Δf| approaches 2.0. Comparison with minimum shift keying (MSK) is also made through simulation     

Sequence‐Independent Synthesis of π‐conjugated Arylenevinylene Oligomers using Bifunctional Thiophene Monomers

Sequence‐independent or “click” chemistry is applied for the preparation of a series of novel and structurally similar π‐conjugated oligomers. The new oligomers are prepared using Wittig–Horner chemistry from bifunctional building blocks that can be interconnected to one another at any desired sequence. The bifunctional building blocks consist of aromatic skeletons with acetal protected aldehyde groups on one side and a phosphonic acid diethyl ester group para to the aldehyde functionality. The first step in the arylenevinylene formation is a Wittig–Horner coupling of a functionalized aldehyde with the methyl phosphonate ester ylide of a bifunctional monomer. A stepwise protection–deprotection process is applied for the preparation of structurally similar π‐conjugated oligo‐phenylene vinylenes. New di‐, tri‐, penta‐, and hepta‐phenylenevinylenes are prepared and characterized. Selected penta‐arylenevinylenes are incorporated as the semiconductor channel in organic field‐effect transistors.     

Studies on arylfuran derivatives-Part VI. Synthesis, characterization and antibacterial activities of some 6-(5-aryl-2-furyl)-1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles and 6-(5-nitro-2-furyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

A series of 4-[5-aryl-2-furfurylidene]amino-3-mercapto-5-substituted-1,2,4-tri azoles and 4-[5-Nitro-2-furfurylidene]amino-3-mercapto-5-substituted-1,2,4-tr iazoles have been synthesized and were converted into 1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles. These triazolothiadiazoles are also synthesized by an alternative method in better yields employing arylfuroic acids and s-triazoles in the presence of phosphorus oxychloride. The newly synthesized compounds are screened for their antibacterial properties.     

Numerical Simulation of Shot Peening Process on Equal Channel Angular Pressed Magnesium Alloy

This paper presents the numerical simulation of inducing residual stresses on equal channel angular pressed (ECAP) magnesium alloy by shot peening process. Mg-Al-Mn (AM) series magnesium alloy was ECAP processed up to 4 passes using route B_C. Microstructures were analysed and grain size reduced from 100 µm for the as-received sample to 3 µm for ECAP 4 pass sample. Tensile test was carried out and maximum tensile strength was found in ECAP 2 pass sample and decreased with higher ECAP passes. Grain refinement was characterized by optical microscopy, electron backscatter diffraction analysis (EBSD) and X-ray diffraction (XRD). Material (tensile) behaviour of 2 pass sample was implemented for finite element modelling. A finite element method was used to estimate the intensity of residual stresses developed due to shot peening in ECAP processed AM80 alloy. Simulation was done with different boundary condition such as impact velocity, geometry of shot-peen media, angle of impact and multiple impacts. The results are presented and the relationship between process parameters and the intensity of residual stresses are discussed. Increase in velocity of shot peening media showed an increase in the magnitude of residual stresses. Change in geometry of shot media altered the contact area between target and shot media during impact which influenced the magnitude of residual stresses and coverage area. The magnitude of residual stresses varied with the angle of impact and the multiple repeated impacts showed that the effective depth of residual stresses increased with the number of impacts.     

The Relation Between Molecular Packing or Morphology and Chemical Structure or Processing Conditions: the Effect on Electronic Properties

In the past few decades, mainly two kind of organic semiconductors, namely small molecules and polymers, have been dealt with. It turns out that the difference between these two categories in terms of charge carrier transport arises from the potentially different morphologies and the molecular packing. There are many studies showing the effect of the chemical structure on the electronic properties. However, in this study, the focus is on the role of processing conditions which is found to be of at least equal importance. To study a range of morphologies and packing in as similar molecules, two systems prepared by “Click”‐type chemistry are chosen, with the major difference between them being the replacement of a flat unit with one that introduces a slight twist to the aromatic skeleton. Through AFM and X‐ray studies, it is shown that the molecule with the potentially flat geometry can exhibit a high degree of π–π stacking, leading to morphologies ranging from polycrystalline to single crystals while the other is always in the amorphous film state. The transport properties are compared using organic field effect transistor (OFETs) in both top and bottom contact configurations.     

Studies on arylfuran derivatives- Part VIII. Synthesis, characterization and antibacterial activities of some 1-aminomethyl-3-substituted-4-[5-(4-nitrophenyl-2-furfurylidene)] amino-1,2,4-triazole-5-thiones

A series of 4-[5-(4-nitrophenyl-2-furfurylidene)]amino-5- mercapto-3-substituted-s-triazoles (3) and their Mannich bases (4) are synthesized. The structures of these compounds are established on the basis of elemental analysis, IR, NMR and mass spectral data. The newly synthesized compounds are screened for their antibacterial activities.