Novel co-evaporation approach for the growth of Sb doped SnO2 nanowires

Antimony doped tin oxide (Sb:SnO2) nanowires were grown by thermal and e-beam assisted co-evaporation of Sb and Sn in the presence of oxygen at a low substrate temperature of 450 degrees C. The field emission scanning electron microscopy study revealed that the nanowires had a length and diameter of 2-4 mu m and 20-60 nm respectively. Transmission electron microscopy study revealed the single crystalline nature of the nanowires; energy dispersive X-ray spectroscopy (EDS) and EDS mapping on the nanowires confirmed the presence of Sb doping in the nanowires. UV light detection study on the doped SnO2 nanowire films exhibited fast response and recovery time compared to undoped SnO2 nanowire films. This is an innovative and simple method to grow doped SnO2 nanowires.

A Novel Monte-Carlo-Sampling-Based Receiver for Large-Scale Uplink Multiuser MIMO Systems

In this paper, we propose low-complexity algorithms based on Monte Carlo sampling for signal detection and channel estimation on the uplink in large-scale multiuser multiple-input-multiple-output (MIMO) systems with tens to hundreds of antennas at the base station (BS) and a similar number of uplink users. A BS receiver that employs a novel mixed sampling technique (which makes a probabilistic choice between Gibbs sampling and random uniform sampling in each coordinate update) for detection and a Gibbs-sampling-based method for channel estimation is proposed. The algorithm proposed for detection alleviates the stalling problem encountered at high signal-to-noise ratios (SNRs) in conventional Gibbs-sampling-based detection and achieves near-optimal performance in large systems with M-ary quadrature amplitude modulation (M-QAM). A novel ingredient in the detection algorithm that is responsible for achieving near-optimal performance at low complexity is the joint use of a mixed Gibbs sampling (MGS) strategy coupled with a multiple restart (MR) strategy with an efficient restart criterion. Near-optimal detection performance is demonstrated for a large number of BS antennas and users (e. g., 64 and 128 BS antennas and users). The proposed Gibbs-sampling-based channel estimation algorithm refines an initial estimate of the channel obtained during the pilot phase through iterations with the proposed MGS-based detection during the data phase. In time-division duplex systems where channel reciprocity holds, these channel estimates can be used for multiuser MIMO precoding on the downlink. The proposed receiver is shown to achieve good performance and scale well for large dimensions.

A Novel Prevailing Torque Threaded Fastener and Its Analysis

We present a novel concept of a threaded fastener that is resistant to loosening under vibration. The anti-loosening feature does not use any additional element and is based on modifying the geometry of the thread in the bolt. In a normal nut and bolt combination, the axial motion of the nut or bolt is linearly related to the rotation by a constant pitch. In the proposed concept, the axial motion in the bolt is chosen to be a cubic function of the rotation, while for the nut, the axial motion remains linearly related to the rotation. This mismatch results in interference during the tightening process and additional torque required to overcome this interference gives rise to the enhanced anti-loosening property. In addition, the cubic curve is designed to ensure that the mismatch results in stresses and deformation in the elastic region of the chosen material. This ensures that the nut can be removed and reused while maintaining a repeatable anti-loosening property in the threaded fastener. A finite element analysis demonstrates the feasibility of this concept.

A Novel Analytical Study of Different Channel Allocations and FWM Efficiencies in Optical WDM Systems

The optical WDM systems are usually affected by the Four Wave Mixing effects. This paper examines the different frequency allocations in terms of FWM efficiency for CWDM, DWDM and for three various proposed modes.

A novel photodegradable hyperbranched polymeric photoresist

We report the first synthesis of a photodegradable hyperbranched polyacetal, wherein every repeat unit carries a photo-labile 2-nitro-benzyloxy moiety. The pristine HBP serves as a positive photoresist to create micron-size patterns; furthermore, by changing the terminal groups to dipropargyl acetal, clickable photo-patterned substrates can be generated.

Exploring novel methods to achieve sensitivity limits for high operating temperature infrared detectors

A review of high operating temperature (HOT) infrared (IR) photon detector technology vis-a-vis material requirements, device design and state of the art achieved is presented in this article. The HOT photon detector concept offers the promise of operation at temperatures above 120 K to near room temperature. Advantages are reduction in system size, weight, cost and increase in system reliability. A theoretical study of the thermal generation-recombination (g-r) processes such as Auger and defect related Shockley Read Hall (SRH) recombination responsible for increasing dark current in HgCdTe detectors is presented. Results of theoretical analysis are used to evaluate performance of long wavelength (LW) and mid wavelength (MW) IR detectors at high operating temperatures. (C) 2013 Elsevier B.V. All rights reserved.

A novel MCMC algorithm for near-optimal detection in large-scale uplink mulituser MIMO systems

In this paper, we propose a low-complexity algorithm based on Markov chain Monte Carlo (MCMC) technique for signal detection on the uplink in large scale multiuser multiple input multiple output (MIMO) systems with tens to hundreds of antennas at the base station (BS) and similar number of uplink users. The algorithm employs a randomized sampling method (which makes a probabilistic choice between Gibbs sampling and random sampling in each iteration) for detection. The proposed algorithm alleviates the stalling problem encountered at high SNRs in conventional MCMC algorithm and achieves near-optimal performance in large systems with M-QAM. A novel ingredient in the algorithm that is responsible for achieving near-optimal performance at low complexities is the joint use of a randomized MCMC (R-MCMC) strategy coupled with a multiple restart strategy with an efficient restart criterion. Near-optimal detection performance is demonstrated for large number of BS antennas and users (e.g., 64, 128, 256 BS antennas/users).

Regioselective Synthesis of 4-Substituted Indoles via C-H Activation: A Ruthenium Catalyzed Novel Directing Group Strategy

A highly regioselective functionalization of indole at the C-4 position by employing an aldehyde functional group as a directing group, and Ru as a catalyst, under mild reaction conditions (open flask) has been uncovered. This strategy to synthesize 4-substituted indoles is important, as this class of privileged molecules serves as a precursor for ergot alkaloids and related heterocyclic compounds.

Insertion Reactions of Six-Membered Cyclopalladated N,N `,N `'-Triarylguanidine, Pd{kappa(2)(C,N)-C6H3Me-3(NHC(NHAr)(=NAr))-2)(mu-Br)](2) (Ar=2-MeC6H4) with PhCC C-C(O)OR (R = Me and Et): A Gateway to Second Orthopalladation through Novel Rearrangements

The reaction of Pd{kappa(2)(C,N)-C6H3Me-3-(NHC(NHAr)(=NAr))-2}(mu-Br)](2) (Ar = 2-MeC6H4; 1) with 4 equiv of PhC C-C(O)OMe in CH2Cl2 afforded Pd{kappa(2)(C,N)-C(Ph)=C(C(O)OMe)C(Ph)=C(C(O)-OMe)C6H3Me-3(N=C(NH Ar)(2))-2}Br] (Ar = 2-MeC6H4; 2) in 70% yield, and the aforementioned reaction carried out with 10 equiv of PhC C-C(O)OR (R = Me, and Et) afforded an admixture of two regioisomers of Pd{kappa(3)(N,C,O)-O=C(OR)-C5Ph3(C(O)OR)C(C(O)OR)C6H3Me-3(N=C(NHAr)( 2))- 2}Br] (Ar = 2-MeC6H4; R = Me (3a/3b), Et (4a/4b)) in 80 and 87% yields, respectively. In one attempt, the minor regioisomer, 4b, was isolated from the mixture in 6% yield by fractional crystallization. Palladacycles 3a/3b and 4a/4b, upon stirring in CH2Cl2/MeCN (1/1, v/v) mixture at ambient condition for S days, afforded Pd{eta(3)-allyl,(KN)-N-1)-C-5(C(O)OR)(2)Ph3C-(C(O)OR)C6H3Me-3(N=C(NH Ar)(2))(-2)}Br] (Ar = 2-MeC6H4; R = Me (5a/5b), Et (6a/6b)) in 94 and 93% yields, respectively. Palladacycles 3a/3b and 4a/4b, upon reaction with AgOTf in CH2CH2/Me2C(O) (1/1, v/v) mixture at ambient temperature for 15 min, afforded Pd{kappa(3)(N,C,O)-O=C(OR)C5Ph3(C(O)OR)C(C(O)OR)C6H3Me-3(N=C(NHAr)(2 ))-2}(OTf)] (Ar = 2-MeC6H4; R = Me (7a/7b), Et (8a/8b)) in 79 and 77% yields, respectively. Palladacycles 7a/7b and 8a/ 8b, upon reflux in PhC1 separately for 6 h, or palladacycles 5a/5b and 6a/6b, upon treatment with AgOTf in CH2Cl2/Me2C(O) (7/3, v/v) mixture for 15 min, afforded Pd{(eta(2)-Ph)C5Ph2(C(O)OR)kappa(2)(C,N)-C(C(O)OR)C6H3Me-3(N=C(NHAr) (2))-2}(OTf)] (Ar = 2-MeC6H4; R = Me (9a/9h), Et (10a/10b)) in >= 87% yields. Palladacycles 9a/9b, upon stirring in MeCN in the presence of excess NaOAc followed by crystallization of the reaction mixture in the same solvent, afforded Pd{kappa(3)(N,C,C)-(C6H4)C5Ph2(C(O)OMe)(2)C(C(O)OMe)(2)C6H3Me-3(N=C( NHAr)(2))-2}(NCMe)] (Ar = 2-MeC6H4; 11a/11b) in 82% yield. The new palladacycles were characterized by analytical, IR, and NMR (H-1 and C-13) spectroscopic techniques, and the molecular structures of 2, 3a, 4a, 4b, 5a, 6a, 7a, 9a, 10a, and 11a-d(3) were determined by single crystal X-ray diffraction. The frameworks in the aforementioned palladacycles, except that present in 2, are unprecedented. Plausible pathways for the formation of new palladacycles and the influence of the guanidine unit in 1, substituents in alkynes, reaction conditions, and electrophilicity of the bromide and the triflate upon the frameworks of the insertion products have been discussed.

In vitro and in silico biological studies of novel thiazolo3,2-a]pyrimidine-6-carboxylate derivatives

In the present study, we report the synthesis, characterization of new series of thiazolo3,2-a]pyrimidine-6-carboxylate derivatives 3a-f and 4a-f. The newly synthesized compounds were screened for in vitro antimicrobial and antiviral activities. The probable mode of action of these active compounds was determined through in silico docking study by docking the receptor methionyl-tRNA synthetase and human inosine-5'-monophosphate dehydrogenase (IMPDH) for antibacterial and antiviral activities, respectively. Among the compounds, 4c exhibited excellent in vitro antimicrobial activity against all tested strains with binding and docking energies -35.6 and -12.4 kcal/mol, respectively. The antiviral studies were carried out for the selected compounds in which 4a exhibited 73.69 and 54.42 % of inhibition of buffalopox and camelpox viruses, respectively. Furthermore, compound 4a showed minimum docking and binding energy along with the maximum hydrogen/hydrophobic interaction with IMPDH. The study contributes towards identification and screening of potential antimicrobial and antiviral agent's against the pathogens.

The exploration of Kemp's triacid (KTA) as the core for the synthesis of 3-fold symmetric 2(3)-cyclophane, 2(2)-cyclophane and novel linker directed designs

For the first time, two units of KTA have been linked to three units of cyst-di-OMe. The reaction is noteworthy since it involves the formation of six amide bonds leading to a three-fold symmetric 23-cyclophane (3) harboring a cluster of three S-S bridges. The major product is a di-imide (4), arising from the interaction of a cystine NH with a neighbouring activated ester. A third reaction of tethering KTA with a single cyst-di-OMe unit afforded the flexible compound 6 and, with benzidine, the novel linker directed 7 with orthogonally disposed anchor modules.

Identification and characterization of novel indole based small molecules as anticancer agents through SIRT1 inhibition

In our pursuit to develop new potential anticancer leads, we designed a combination of structural units of indole and substituted triazole; and a library of 1-{1-methyl-2-4-phenyl-5-(propan-2-ylsulfanyl)-4H-1,2,4-triazol-3-yl ]-1H-indol-3-yl}methanamine derivatives was synthesized and characterized. Cytotoxic evaluations of these molecules over a panel of three human cancer cell lines were carried out. Few molecules exhibited potent growth inhibitory action against the treated cancer cell lines at lower micro molar concentration. An in vitro assay investigation of these active compounds using recombinant human SIRT1 enzyme showed that one of the compounds (IT-14) inhibited the deacetylation activity of the enzyme. The in vivo study of IT-14 exemplified its promising action by reducing the prostate weight to the body weight ratio in prostate hyperplasia animal models. A remarkable decrease in the disruption of histoarchitecture of the prostate tissues isolated from IT-14 treated animal compared to that of the positive control was observed. The molecular interactions with SIRT1 enzyme were also supported by molecular docking simulations. Hence this compound can act as a lead molecule to treat prostatic hyperplasia. (C) 2013 Elsevier Masson SAS. All rights reserved.

Novel 2,6-bis(4-methoxyphenyl)-1-methylpiperidin-4-one oxime esters: synthesis and a new insight into their antioxidant and antimicrobial potential

A simple and efficient protocol for the synthesis of novel 2,6-bis(4-methoxyphenyl)-1-methylpiperidin-4-one oxime esters 4(a-q) is described. Initially, p-anisaldehyde 1 was condensed (Mannich reaction) with acetone and ammonium acetate trihydrate afforded 2,6-bis(4-methoxyphenyl)piperidin-4-one 2. Then, methylation followed by oximation with hydroxylamine hydrochloride (NH(2)OHa (TM) HCl) furnished a key scaffold 4. Further, to explore the enhanced biological properties of the piperidin-4-one core i.e. the key scaffold 4 was conjugated with substituted benzoyl chlorides in the presence of anhydrous K2CO3 as base to obtain novel 2,6-bis(4-methoxyphenyl)-1-methylpiperidin-4-one oxime esters 4(a-q) in excellent yields. The newly synthesized compounds were characterized by elemental analysis, IR, H-1 NMR, C-13 NMR and mass spectroscopic techniques, and screened for their in vitro antioxidant and antimicrobial activities. Most of the compounds exerted positive efficacy towards the biological assays performed. Among the synthesized analogues, compounds 4l and 4m exhibited promising antioxidant activity and on the other hand compounds 4b and 4d manifested persuasive antibacterial activity, whereas compound 4b displayed stupendous antifungal activity against A. flavus strain.

Impedance spectroscopy of novel hybrid composite films of polyvinylbutyral (PVB)/functionalized mesoporous silica

Polyvinyl butyral/functionalized mesoporous silica hybrid composite films have been fabricated by solution casting technique with various weight percentages of functionalized silica. A polyol (tripentaerythritol-electron rich component), which acts as an electron donor to the polymer backbone, was added to enhance the conductivity. The prepared composites were characterized by Fourier transformed infrared spectroscopy and the morphology was evaluated by scanning electron microscopy. Dielectric properties of these freestanding composites were studied using the two-probe method. The dielectric constant and impedance value decreased with the increase in applied frequency as well as with the increase in functionalized silica content in the polyvinyl butyral matrix. An increase in conductivity of the PVB/functionalized silica composites was also observed. (C) 2013 Elsevier Ltd. All rights reserved.