Properties of amorphous silicon films— Dependence on deposition conditions

We report measurements on the electrical conductivity, optical absorption, electron spin resonance, Raman spectrum and electron diffraction of a set of a-Si films vaccum deposited at room temperature. As revealed by absorption at about 10 μm some of the films grown at deposition rates of about 0.4 Å/sec contain considerable amounts of oxygen. All the properties, except Raman spectra and electron diffraction, are found to vary strongly with the deposition rate and the background pressure during evaporation. Qualitatively, these variations show significant correlations. For instance, if the electrical conductivity is higher so is the spin density, the optical absorption and the low-frequency refractive index. Also, increasing oxygen content leads to lower conductivity. In addition, we have tried to establish a rough quantitative relation between the shift in the optical gap and the change in the spin density by connecting each of these changes to the variation in the low-frequency refractive index. The temperature dependence of the electrical conductivity was also measured and it was found that below about 150 K the data are consistent with recent theoretical predictions, i.e., log σ exhibits a ($\text{1/T)}{}^{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}$ dependence.     

Investigation of free space optical communication using spectrum slicing under different weather condition

Optical Review - Free space optical communication (FSO) is growing technology with attractive features like high data rate, no license requirement, high security, and easy installation. But FSO is...     

Isolation of Homo-/Mixed-Valence Ag12, Ag29, and Ag8 Clusters Stabilized by Cyclic Alkyl(amino) Carbene-Anchored Monoanionic Phosphorus Ligand

Silver clusters are attractive candidates for their promising optical properties, and biomedical activities. Herein, we report on the first syntheses and isolation of three homo-/mixed-valence silver nanoclusters (NCs) with Ag₁₂Cl₃, Ag₂₉, and Ag₈ cores [((cAAC)P)₆Ag₁₂Cl₃](OTf)₃ ( 1 ), [((cAAC)P)₆Ag₂₉] ( 2 ), and [((cAAC)P)₄Ag₈] ( 3 ) having three-/twofold symmetry, employing cyclic alkyl(amino) carbene (cAAC)-supported phosphinidenide (cAACP⁻) as the π-accepting stabilizing ligand. The average diameters of Ag NCs 1 , and 2 are approximately 1.6 to 2 nm. The redox non-innocent mono-atomic phosphorus anions (P⁻) anchored with cAAC ligands are generated in situ by the reaction of AgOTf with a boryl-phosphaalkene (cAAC)P−B(NⁱPr₂)₂ through cleavage of the P−B bond with the help of a triflate anion (OTf⁻) as a weak nucleophile. Equivalent number of the (cAAC)P⁻ anions generated in situ are oxidized to produce the corresponding bis-phosphinidene (cAAC)₂P₂ leading to the generation of Ag⁰ ions in solution for the formation of the unprecedented mixed-valence Ag NC 2 . Complex 3 is achieved by treating potassium phosphinidenide cAACPK with AgNTf₂. The ligand field and the steric hindrance of the (cAAC)P units play crucial roles in stabilizing complexes 1 – 3 , further providing a three- ( 1 , 2 )/two- ( 3 ) fold stand. The Ag₁₂Cl₃ NC ( 1 ) with a tricationic core [Ag^I₁₂Cl₃] was found to be diamagnetic, and fluorescent, emitting green light at 563 nm when excited at 400 nm. In contrast, the neutral Ag₂₉ ( 2 ) and Ag₈ ( 3 ) clusters were found to be paramagnetic, and NMR silent showing characteristic EPR signals for Ag⁰ at room temperature.     

Reply to Comment on: Ab initio calculations of B<Subscript>2</Subscript> type RHg (R = Ce,Pr,Eu and Gd) intermetallic compounds

Dr. Salah Daoud pointed out the mistakes in formulae used for Debye temperature, soundvelocities and suggested corrections. We duly acknowledge the corrections pointed out byDr. Salah Daoud and also appreciate his focused study of our paper.     

A Tale of Biphenyl and Terphenyl Substituents for Structurally Diverse Ketiminato Magnesium,Calcium and Germanium Complexes

In this paper, we have used two N,O‐ketiminato ligands ( L1 and L2 ) with biphenyl and terphenyl substituent on the nitrogen atom. Deprotonation of L1 with KN(SiMe₃)₂ and subsequent reaction with MgI₂ led to a homoleptic dinuclear magnesium complex ( 1 ) with a Mg₂O₂ four‐membered ring. Deprotonation with nBuLi and subsequent reaction with MgI₂ afforded a unusual dinuclear magnesium complex ( 2 ) with a Mg₂O₂ ring. Extension of the ligand for calcium resulted in a trinuclear calcium complex ( 3 ) with six four‐membered Ca₂O₂ rings. We could not isolate any chelating complex when L2 was used as a ligand, and only oxygen bound magnesium ( 4 ) and calcium ( 5 ) adducts were isolated. DFT studies were performed to understand this dissimilar behavior. More diverse results were obtained when lithiated L1 and L2 were treated with germanium dichloride. We were able to stabilize a monomeric germylene monochloride ( 7 ) with L1 . However, with L2 , an unusual ligand scrambling, and a C?C coupling take place, leading to the formation of a secondary carbocation with GeCl₃‐ as a counter‐anion ( 8 ). Besides, a germanium dichloride adduct ( 9 ) bound to the oxygen center of the ligand was obtained as the minor product.     

In vitro antimicrobial evaluation,effects of halide concentration and hemolysis study of silver-N-heterocyclic carbene complexes

Research on Chemical Intermediates - The morpholine containing silver complexes were screened for the zone of inhibition, MIC determination, and longevity studies against bacterial growth. The most...     

β-Cyclodextrin catalyzed one-pot four component auspicious protocol for synthesis of spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-trione as a potential antimicrobial agent

We have developed an perceptive and facile approach for the synthesis of new spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-trione derivatives (4a–t) by one-pot four component condensation involving two equivalence of dimedone (1), substituted anilines (2a–t), and isatin (3) catalyzed by β-cyclodextrin in water within short reaction time at 80?°C in good to excellent yields. We believe that this novel procedure may open the door for the easy generation of new and bioactive spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-triones. The most exciting feature of this methodology is its mechanism involving the unusual ring opening of an isatin moiety followed by recyclization. Synthesized compounds were evaluated for their antimicrobial activities against four bacteria and three fungi. All the spirooxindole derivatives exhibited significant antibacterial activity against bacteria and fungi. Among 20 compounds screened, compound (4i) and (4h) was found to be more active against tested bacterial strain.     

Transferrin-tailored solid lipid nanoparticles as vectors for site-specific delivery of temozolomide to brain

Journal of Nanoparticle Research - A sunlight irradiation strategy was developed for the synthesis of concave gold nanoplates in the presence of polydiallyldimethylammonium chloride (PDDA) as the...     

Convenient synthesis of imidazolium based dicationic ionic liquids

Research on Chemical Intermediates - A series of imidazolium based Dicationic Ionic Liquids (ILs) have been prepared and characterized successfully. Derivatives are prepared keeping the alkyl chain...     

Rational approaches for the design of various GABA modulators and their clinical progression

Molecular Diversity - GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role...