bluuebunny/crossref_metadata_2025 huggingface dataset:
A Re‐Examination of the Reaction of 3,4‐Diamino[1,2,5]oxadiazole with Glyoxal
Authors: Willer Rodney L. , Storey Robson F. , Campbell Christopher G. , Bunte Steven W. , Parrish Damon
Published: September 2012

Reaction coordinate mapping was used to study the reaction of 3,4‐diamino[1,2,5]oxadiazole (3,4‐diaminofurazan) and 3,4‐diamino[1,2,5]thiadiazole with glyoxal. The thiadiazole was known to give a good yield of [1,2,5]thiadiazolo[3,4‐b]pyrazine, whereas the oxadiazole had not yielded, until now, [1,2,5]oxadiazolo[3,4‐b]pyrazine (or furazano[2,3‐b]pyrazine). The calculations suggested that the diols, 5,6‐dihydroxy‐4,5,6,7‐tetrahydro[1,2,5]oxadiazolo[3,4‐b]pyrazine and 5,6‐dihydroxy‐4,5,6,7‐tetrahydro[1,2,5]thiadiazolo[3,4‐b]pyrazine should be stable intermediates, and once formed, should provide a pathway to the target compounds via two dehydration steps, under forcing conditions. With this information in mind, the reactions of 3,4‐diamino[1,2,5]oxadiazole with glyoxal and pyruvic aldehyde were re‐examined. The reaction of 3,4‐diamino[1,2,5]oxadiazole with glyoxal and pyruvic aldehyde produced, under slightly basic conditions, a near quantitative yield of the expected initial products, 5,6‐dihydroxy‐4,5,6,7‐tetrahydro[1,2,5]oxadiazolo[3,4‐b]pyrazine and the 5‐methyl analog, respectively. The diols were easily isolated by lyophilizing the aqueous reaction mixture. The diols were pyrolized on silica gel at 160°C to give the desired [1,2,5]oxadiazolo[3,4‐b]pyrazine and the 5‐methyl analog. Both compounds were easily reduced to the corresponding 4,5,6,7‐tetrahydro‐derivative using sodium borohydride in THF/methanol. The [1,2,5]oxadiazolo[3,4‐b]pyrazine also displayed other interesting chemistry.
Design, Synthesis, Characterization, and Antimicrobial Activity of Biginelli Products of Indandione
Authors: Dabholkar Vijay V. , Patil Sunil R. , Pandey Rajesh V.
Published: September 2012

A simple and efficient method has been developed for the synthesis of 4‐(substituted phenyl)‐3,4‐dihydro‐1H‐indeno [1,2‐d] pyrimidine‐2,5‐dione (5) and 4‐(substituted phenyl)‐2‐thioxo‐1,2,3,4‐tetrahydroindeno [1,2‐d] pyrimidine‐5‐one (6), by a one‐pot three component cyclocondensation reaction of 1,3 dicarbonyl compound (Indandione) (1), aromatic aldehyde (2), and urea/thiourea (3/4) using catalytic amount of conc. HCl in refluxing ethanol. Representative samples were screened for their antimicrobial activity against gram‐negative bacteria, E coli and Paeruginosa and gram‐positive bacteria, S aureus, and C diphtheriae using disc diffusion method. The structures of the products were confirmed by IR, 1H, 13C NMR, and elemental analysis.
K2CO3/H2O in [omim][BF4] Ionic Liquid: A Green Medium for Efficient Room‐Temperature Synthesis of N‐Substituted 1,4‐Benzoxazin‐3‐ones
Authors: Sharifi Ali , Barazandeh Mehdi , Abaee M. Saeed , Mirzaei Mojtaba
Published: September 2012

A medium consisting of K2CO3 and H2O in [omim][BF4] ionic liquid (IL) was used to synthesize N‐substituted 2H‐benzo[b][1,4]oxazin‐3(4H)‐one derivatives from their corresponding o‐aminophenols and 2‐bromoalkanoates. As a result, chemoselective formation of benzoxazinones in high yields has been observed at room temperature. After the reactions and separation of the products, the IL was recovered and successfully reused in subsequent reactions without significant loss of activity.
Facile Synthesis of 3,6‐Disubstituted‐1,2,4‐triazolo‐[3,4‐b]‐1,3,4‐thiadiazoles via Oxidative Cyclization of n‐Heteroaryl‐Substituted Hydrazones and Their Biological Activity
Authors: Himaja M. , Prathap K. Jagadeesh , Mali Sunil V.
Published: September 2012

Fused 3,6‐disubstituted triazolothiadiazoles were synthesized in good yield from a rapid and convenient oxidative cyclization of N‐heteroaryl‐substituted hydrazones promoted by chloramine‐T trihydrate at ambient temperature. The structure of the synthesized compounds was confirmed by FTIR, 1H NMR, 13C NMR, and mass spectral data. The synthesized compounds were evaluated for their antioxidant and antitubercular activities. All the compounds 5a‐i and 6a‐i showed good antitubercular activity. However, only compounds 5a‐i showed good antioxidant activity.
Synthesis of Novel 5,6‐Dihydropyrrolo[2,1‐a]isoquinolines via Grob Reaction between (E)‐1,1,1‐Trifluoro‐3‐nitro‐2‐butene and 3,4‐Dihydroisoquinolines
Authors: Korotaev Vladislav Y. , Sosnovskikh Vyacheslav Y. , Barkov Alexey Y. , Slepukhin Pavel A. , Shklyaev Yurii V.
Published: September 2012

Uncatalyzed cycloaddition of 3,4‐dihydroisoquinolines to (E)‐1,1,1‐trifluoro‐3‐nitro‐2‐butene via Grob reaction provide a simple one‐step route to the 5,6‐dihydropyrrolo[2,1‐a]isoquinolines, which represent the basic structural framework of the antitumor active alkaloid crispine.
Novel Synthesis and Antimicrobial Activity of 3‐Substituted 5‐bromo‐7‐methyl‐1,2,4‐triazolo‐[3,4‐b]‐benzothiazoles
Authors: Bhagat T. M. , Deshmukh S. K. , Kuberkar S. V.
Published: September 2012

4‐Methyl acetanilide (1) on treatment with bromine in acetic acid, followed by hydrolysis with dilute HCl/NaOH solution, yielded 2‐bromo‐4‐methyl aniline (2), which on treatment with sodium thiocyanate in acetic acid afforded 2‐amino‐4‐bromo‐6‐methyl benzothiazole (3). Compound 3 in ethylene glycol was heated at 150°C with 80% hydrazine hydrate to get 4‐bromo‐2‐hydrazino‐6‐methyl benzothiazole (4). This hydrazino compound 4 on heating with formic acid for 3 h yielded 4‐bromo‐2‐hydrazinoformyl‐6‐methyl benzothiazole (5). Same compound 4 when heated independently with formic acid for 6 h/urea for 3 h/carbon disulfide in alkali afforded 5‐bromo‐7‐methyl (6)/5‐bromo‐3‐hydroxy‐7‐methyl (7)/5‐bromo‐3‐mercapto‐7‐methyl (8)‐1,2,4‐triazolo‐[3,4‐b]‐benzothiazoles, respectively. Compound 4 on heating with acetic acid/acetic anhydride gave acetyl benzothiazolyl derivative 9, which on cyclization with orthophosphoric acid yielded 5‐bromo‐3,7‐dimethyl‐1,2,4‐triazolo‐[3,4‐b]‐benzothiazole (10). All these newly synthesized compounds were screened for antimicrobial activity against Escherichia coli (Gram −ve), Bacillus subtilis (Gram +ve), Erwinia carotovora, and Xanthomonas citri using ampicillin, streptomycin, and penicillin as a standard for comparison.
A Novel Synthesis of 4‐Pyridazineacetic Acids viaRing Expansion of N‐Cyanomethylated 3‐Pyrazoline‐4‐acetic Acids
Authors: Masumoto Eiichi , Maruoka Hiroshi , Okabe Fumi , Nishida Sho , Tomita Ryoko , Fujioka Toshihiro , Yamagata Kenji
Published: September 2012

A novel synthetic route to 4‐pyridazineacetic acids 10–12 has been achieved by the ring‐expansion reaction of N‐cyanomethylated 3‐pyrazoline‐4‐acetic acids 7–9. 1H‐Pyrazole‐4‐acetic acids 1–3 were reacted with iodoacetonitrile in the presence of triethylamine in refluxing acetonitrile to give the corresponding C‐cyanomethylated 1H‐pyrazole‐4‐acetic acids 4–6 as major products together with N‐cyanomethylated 3‐pyrazoline‐4‐acetic acids 7 and 8 as minor products. On the other hand, reactions of 1 and 3 with chloroacetonitrile in the presence of triethylamine in refluxing chloroform afforded the corresponding N‐cyanomethylated 3‐pyrazoline‐4‐acetic acids 7 and 9 as major products. Thermal treatment of 7–9 with sodium hydride in N,N‐dimethylformamide caused ring expansion to yield the corresponding 4‐pyridazineacetic acids 10–12.
Synthesis of Thieno[2,3‐b]quinolinone Derivatives
Authors: Han Guang‐Fan , Wang Ming , Chen Li‐Zhuang , Hu Xiao‐Lei
Published: September 2012

The Knoevenagel reactions of malononitrile with acetophenone or 4‐substituted acetophenons were carried to give the corresponding 2‐(1‐aryle thylidene)malononitriles, which was further cyclized with sulfur using NaHCO3 as catalysts to generate 2‐amino‐5‐arylthiophene‐3‐carbonitrile 2. The intermediate enamines 3 were prepared by refluxing of 2 with 5‐substituted‐1,3‐cyclohexanedione using p‐toluenesulfonic acid as catalyst. The title compounds 4‐amino‐3‐aryl ‐7‐substituted‐7,8‐dihydrothieno[2,3‐b]quinolin‐5(6H)‐one were synthesized by cyclization of 3 in the presence of K2CO3 and Cu2Cl2. The structures of all compounds were characterized by elemental analysis, IR, MS, and 1H‐NMR spectra.
A Novel Method for the Synthesis of Spiro[indoline‐Pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidine]triones by Alum as a Reusable Catalyst
Authors: Shirvan Sadif A. , Ghahremanzadeh Ramin , Moghaddam Mojtaba Mirhosseini , Bazgir Ayoob , Zarnani Amir Hassan , Akhondi Mohammad Mehdi
Published: September 2012

Synthesis of spiro[indoline‐pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidine]trione derivatives by a cyclo‐condensation reaction of indolin‐2‐ones, barbituric acids, and 1,3‐diphenyl‐1H‐pyrazol‐5‐amines with the ionic liquid as an effective green reaction media and in the presence of Alum as a reusable catalyst was reported. Excellent yields of products, green media, use of a reusable catalyst, and short reaction time are the main advantages of this new method.
An Improved Synthesis of Carbazoles via Domino Reaction of N‐Protected‐2‐methylindoles with DMF‐DMA/DMA‐DMA
Authors: Sureshbabu Radhakrishnan , Mohanakrishnan Arasambattu K.
Published: September 2012

An efficient synthesis of carbazole analogs has been achieved via interaction of N‐protected‐2‐methylindoles with N,N‐dimethylformamide dimethylacetal as well as N,N‐dimethylacetamide dimethylacetal in the presence of pyrrolidine or 1,4‐diazabicyclo(2.2.2)octane (DABCO).
Acid Catalyzed tert‐Butylation and Tritylation of 4‐Nitro‐1,2,3‐triazole: Selective Synthesis of 1‐Methyl‐5‐nitro‐1,2,3‐triazole via 1‐tert‐Butyl‐4‐nitro‐1,2,3‐triazole
Authors: Filippova Yuliya V. , Sukhanova Anna G. , Voitekhovich Sergei V. , Matulis Vadim E. , Sukhanov Gennady T. , Grigoriev Yury V. , Ivashkevich Oleg A.
Published: September 2012

4‐Nitro‐1,2,3‐triazole was found to react with tert‐butanol in concentrated sulfuric acid to yield 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole as the only reaction product, whereas tert‐butylation and tritylation of 4‐nitro‐1,2,3‐triazole in presence of catalytic amount of sulfuric acid in benzene was found to provide mixtures of isomeric 1‐ and 2‐alkyl‐4‐nitro‐1,2,3‐triazoles with predominance of N2‐alkylated products. A new methodology for preparation of 1‐alkyl‐5‐nitro‐1,2,3‐triazoles from 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole via exhaustive alkylation followed by removal of tert‐butyl group from intermediate triazolium salts was demonstrated by the example of preparation of 1‐methyl‐5‐nitro‐1,2,3‐triazole.
Adsorption and catalysis of flavonoid quercetin on different plasmonic metal nanoparticles monitored by SERS
Authors: Jurasekova Z. , Domingo C. , Garcia‐Ramos J. V. , Sanchez‐Cortes S.
Published: September 2012

Raman and surface‐enhanced Raman scattering spectroscopy were used to follow the chemical modification of quercetin (QUC) on silver nanoparticles. Different metallic systems were fabricated to check the influence of the interface, in terms of electric charge or total available surface, on the catalytic change undergone by QUC. The effect of QUC surface coverage was crucial to reveal information about the different orientation and the interaction mechanism with the metal at different concentrations of this flavonoid. Surface‐enhanced Raman scattering spectra of good quality of QUC were observed at concentrations down to 10–8 M. Chemical modifications in the presence of nanostructure metal surfaces include oxidation followed by a subsequent polymerization via a condensation of rings whereas different chemical species have been recognized under different experimental conditions. The assignment of the new species formed on the metal surface was conducted. Copyright © 2012 John Wiley & Sons, Ltd.
Layer‐dependent resonant Raman scattering of a few layer MoS2
Authors: Chakraborty Biswanath , Matte H. S. S. Ramakrishna , Sood A. K. , Rao C. N. R.
Published: September 2012

We report resonant Raman scattering of MoS2 layers comprising of single, bi, four and seven layers, showing a strong dependence on the layer thickness. Indirect band gap MoS2 in bulk becomes a direct band gap semiconductor in the monolayer form. New Raman modes are seen in the spectra of single‐ and few‐layer MoS2 samples which are absent in the bulk. The Raman mode at ~230 cm−1 appears for two, four and seven layers. This mode has been attributed to the longitudinal acoustic phonon branch at the M point (LA(M)) of the Brillouin zone. The mode at ~179 cm−1 shows asymmetric character for a few‐layer sample. The asymmetry is explained by the dispersion of the LA(M) branch along the Γ‐M direction. The most intense spectral region near 455 cm−1 shows a layer‐dependent variation of peak positions and relative intensities. The high energy region between 510 and 645 cm−1 is marked by the appearance of prominent new Raman bands, varying in intensity with layer numbers. Resonant Raman spectroscopy thus serves as a promising non invasive technique to accurately estimate the thickness of MoS2 layers down to a few atoms thick. Copyright © 2012 John Wiley & Sons, Ltd.
Postoperative 125I brachytherapy delivered by digital model obturators for recurrent or locally advanced maxillary cancers
Authors: Huang Ming‐wei , Zhang Jian‐guo , Tong Dai , Zhang Jie , Zheng Lei , Zhang Yi , Yu Guang‐yan
Published: September 2012

Objectives/Hypothesis:

We aimed to evaluate the feasibility and effectiveness of postoperative 125I brachytherapy delivered by use of digital model obturators for recurrent or locally advanced maxillary cancers.

Study Design:

Retrospective study.

Methods:

From 2006 to 2008, 12 patients (seven females; median age, 65 years; range, 22–86 years) with recurrent or locally advanced maxillary cancers showing positive margins after surgery underwent 125I brachytherapy by use of digital model obturators and interstitial implants. The radioactivity was 18.5 to 33.3 MBq per seed, and the prescription dose was 80 to 160 Gy. Functional outcome of patients was evaluated by the Performance Status Scale (PSS) for head and neck cancer before and after brachytherapy.

Results:

The 125I seeds and dosages were well distributed in the radiation fields, and all patients had higher PSS scores after than before treatment with obturators. During a median follow‐up of 53 months (range, 28–62 months), local control at 3 and 5 years was 83.3% and 66.7%, respectively, with a mean local control time of 53.5 ± 3.79 months. Overall survival at 3 and 5 years was 91.7% and 71.4%, respectively, with a mean survival time of 56.6 ± 2.99 months. Two patients died due to local recurrence, and one patient died due to lung metastasis. No patient had severe complications during follow‐up.

Conclusions:

125I brachytherapy delivered by digital model obturator is effective in treating maxillary cancers with positive margins after maxillectomy for advanced or recurrent cancer. The method may improve the quality of life of patients with maxillary defects. Laryngoscope, 2012
Total airway reconstruction
Authors: Connor Matthew P. , Barrera Jose E. , Eller Robert , McCusker Scott , O'Connor Peter
Published: September 2012

We present a case of obstructive sleep apnea (OSA) that required multilevel surgical correction of the airway and literature review and discuss the role supraglottic laryngeal collapse can have in OSA. A 34‐year‐old man presented to a tertiary otolaryngology clinic for treatment of OSA. He previously had nasal and palate surgeries and a Repose tongue suspension. His residual apnea hypopnea index (AHI) was 67. He had a dysphonia associated with a true vocal cord paralysis following resection of a benign neck mass in childhood. He also complained of inspiratory stridor with exercise and intolerance to continuous positive airway pressure. Physical examination revealed craniofacial hypoplasia, full base of tongue, and residual nasal airway obstruction. On laryngoscopy, the paretic aryepiglottic fold arytenoid complex prolapsed into the laryngeal inlet with each breath. This was more pronounced with greater respiratory effort. Surgical correction required a series of operations including awake tracheostomy, supraglottoplasty, midline glossectomy, genial tubercle advancement, maxillomandibular advancement, and reconstructive rhinoplasty. His final AHI was 1.9. Our patient's supraglottic laryngeal collapse constituted an area of obstruction not typically evaluated in OSA surgery. In conjunction with treating nasal, palatal, and hypopharyngeal subsites, our patient's supraglottoplasty represented a key component of his success. This case illustrates the need to evaluate the entire upper airway in a complicated case of OSA. Laryngoscope, 2012
Prevention of gentamicin‐induced apoptosis with the mitochondria‐targeted antioxidant mitoquinone
Authors: Ojano‐Dirain Carolyn P. , Antonelli Patrick J.
Published: September 2012

Objectives/Hypothesis:

Antioxidants have been shown to protect against aminoglycoside‐induced hearing loss. Mitoquinone (MitoQ) is a mitochondria‐targeted derivative of the antioxidant ubiquinone. MitoQ is attached to a lipophilic triphenylphosphonium (TPP) cation, which enables its accumulation inside the mitochondria several hundred‐fold over the untargeted antioxidant. The goals of this study were to determine if MitoQ attenuates gentamicin‐induced activation of caspase‐3/7 activity as a marker of apoptosis and to determine if MitoQ impacts aminoglycoside antimicrobial efficacy.

Study Design:

Prospective and controlled.

Methods:

Antibiotic efficacy and minimum inhibitory concentrations (MICs) of gentamicin against three strains each of Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa were evaluated with and without MitoQ using broth dilution methods. Apoptosis was assessed by caspase‐3/7 activity in untreated HEI‐OC1 cells and cells exposed to 2 mM gentamicin for 24 hours, with and without a 24‐hour preincubation with 0.5 μM each of MitoQ, idebenone (an untargeted ubiquinone), or decylTPP (positive control).

Results:

Gentamicin MICs for P aeruginosa and H influenzae were not affected by MitoQ at pharmacological levels. MICs for S aureus were enhanced by MitoQ. Cell viability was significantly lower in the gentamicin‐treated cells. A significant increase in caspase‐3/7 activity was observed in cells treated with gentamicin or with idebenone + gentamicin (P = .005). Preincubation with MitoQ decreased the gentamicin‐induced apoptosis of HEI‐OC1 cells to a greater extent compared to idebenone (P = .002).

Conclusions:

MitoQ attenuates gentamicin‐induced apoptosis in HEI‐OC1 cells and does not compromise gentamicin antibiotic efficacy. MitoQ holds promise as a means of preventing aminoglycoside ototoxicity. Laryngoscope, 2012
Interpolated subcutaneous fat pedicle melolabial flap for large nasal lining defects
Authors: Griffin Garrett R. , Chepeha Douglas B. , Moyer Jeffrey S.
Published: September 2012

Full‐thickness nasal deformities are a reconstructive challenge. Restoration of a reliable internal lining is critical for a successful reconstruction. Septal hinge flaps are the workhorse for internal lining defects. However, these and other intranasal mucosal flaps are sometimes unavailable due to prior harvest or previous oncologic resection. We present the two‐stage interpolated subcutaneous fat pedicle melolabial flap for lining large defects when traditional intranasal flaps are unavailable. This approach is particularly useful when one forehead flap has already been expended, preserving the patient's remaining forehead tissue for external cover. Laryngoscope, 2012
Micro‐Engineered 3D Scaffolds for Cell Culture Studies
Authors: Greiner Alexandra M. , Richter Benjamin , Bastmeyer Martin
Published: September 2012

Cells in physiological 3D environments differ considerably in morphology and differentiation from those in 2D tissue culture. Naturally derived polymer systems are frequently used to study cells in 3D. These 3D matrices are complex with respect to their chemical composition, mechanical properties, and geometry. Therefore, there is a demand for well‐defined 3D scaffolds to systematically investigate cell behavior in 3D. Here, fabrication techniques, materials, architectures, biochemical functionalizations, and mechanical properties of 3D scaffolds are discussed. In particular, work focusing on single cells and small cell assemblies grown in tailored synthetic 3D scaffolds fabricated by computer‐based techniques are reviewed and the influence of these environments on cell behavior is evaluated.

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Encapsulation of Photosensitizer into Multilayer Microcapsules by Combination of Spontaneous Deposition and Heat‐Induced Shrinkage for Photodynamic Therapy
Authors: Han Yuanyuan , Bu Jing , Zhang Yuying , Tong Weijun , Gao Changyou
Published: September 2012

Annealing of PDADMAC/PSS multilayer microcapsules assembled on PSS‐doped CaCO3 particles at 80 °C for 30 min reduces their size dramatically from 6.9 ± 0.3 to 3.1 ± 0.5 µm. Methylene blue molecules are encapsulated by spontaneous deposition and post‐annealing with a concentration of 22 mg · mL−1, which is 1000 times higher than the feeding value. The unreleased MB molecules are retained stably for a long time, which are then protected by the capsules against reductive enzymes and keep their photodynamic activity. The viability of HeLa cells incubated with the MB‐loaded capsules decreases sharply from ≈75 (dark cytotoxicity) to ≈20% after irradiation with a laser at 671 nm and 60 J · cm−2 for 75 s.

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Design of a Cellular‐Uptake‐Shielding Magnetic Catcher for Cancer Cell Separation
Authors: Wang Ya , Zhang Jing , Jia Hui‐Zhen , Yang Juan , Qin Si‐Yong , Liu Chen‐Wei , Zhuo Ren‐Xi , Zhang Xian‐Zheng
Published: September 2012

Fluorescent‐magnetic‐biotargeting multifunctional microcapsules (FMBMMs) are designed and fabricated via layer‐by‐layer assembly. It is found that the arginine‐glycine‐aspartate‐modified FMBMMs were capable of sensitively detecting and efficiently isolating approximately 80% target cancer cells within 20 min. More importantly, FMBMMs present a general template for identifying and separating multiple types of cancer cells simply by altering the recognition motif.

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Rheology and biodegradation of polylactide/silica nanocomposites
Authors: Li Yi , Han Changyu , Bian Junjia , Han Lijing , Dong Lisong , Gao Ge
Published: September 2012

Silica‐filled polylactide (PLA) nanocomposites were prepared by melt compounding. The oscillatory rheological properties and biodegradation behavior were then investigated. As the silica loadings reach up to 5 wt%, percolated silica network structures form. For the percolated PLA/silica nanocomposites sample (the silica content was >5 wt%), the modulus enhances with an increase of temperature evidently. Moreover, it is interesting to find that the biodegradation rates have been enhanced obviously in the PLA/silica nanocomposites than in neat PLA. The erosion mechanism of neat PLA and the PLA/silica nanocomposites was further discussed. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Improvement of polyamide 1010 with silica nanospheres via in situ melt polycondensation
Authors: Yan Manqing , Yang Hongjun
Published: September 2012

Polyamide 1010 (PA1010) had been prepared by in situ melt polycondensation in presence of silica nanospheres with amine groups on the surfaces (SiO2NH2). Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) measurements demonstrated that the nanosphere surface was grafted with PA1010 chains. Wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) measurements showed that the PA1010/SiO2NH2 nanocomposites had a lower degree of crystallinity (χc) in comparison with PA1010 and PA1010/SiO2 nanocomposites. Dynamic mechanical analysis (DMA) indicated that SiO2NH2 nanospheres improved glass transition temperature (Tg), tensile strength and storage modulus of PA1010 since SiO2–NH2 nanospheres limited the mobility of PA1010 chains. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Improving the bonding strength of laminated composites by optimizing fabric composition
Authors: Mahmood Ali Hasan , Gong R.H. , Porat I.
Published: September 2012

Delamination is the most common failure mode in laminated composites due to the weaker strength in the through‐the‐thickness direction. Air‐jet texturing is used to produce bulk and loops in the yarn which provides more contact surface between fibers and resin. The development and characterization of core‐and‐effect textured glass yarns and the effect of texturing on the mechanical properties of laminated composites were presented in previous papers. This article describes the optimization of textured composites by varying the type and combination of constituent yarns for improving the mechanical properties. Composites with combinations of various textured yarns and non‐textured yarns were made. It was observed that the composites made from fabrics having non‐textured yarn in the warp and core‐and‐effect textured yarn in the weft had the best combination of mechanical properties. They maintained the tensile and flexure properties of composites with non‐textured yarns but had significantly higher interlaminar shear strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Influence of silane‐coupling agents on the performance of morphological, mechanical, thermal, electrical, and rheological properties of polycarbonate/fly ash composites
Authors: Parvaiz Mohammad Rahail
Published: September 2012

Fly ash, waste product of thermal power station, generated in huge quantities has been posing problems of its disposal. As such, it contains a variety of inorganic oxide and is available in finely powder form. Attempts have been made for its utilization, as filler in engineering plastic. The fly ash (FA) fillers reinforced polycarbonate (PC) composites were fabricated using a economically and environmentally viable method of melt extrusion and compression molding technique. The FA surface was chemically modified using vinyltrimethoxysilane and 3–Aminopropyltriethoxysilane. The feasibility of using treated FA/PC composites was examined in terms of scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and rheological behavior. The morphology shows a good dispersion and strong interfacial interaction between PC and modified FA than the unmodified counterpart. Mechanical investigation manifested that modified FAs have strengthening effect (increase in tensile and flexural strength) on the mechanical performance of PC composites. Rheological behavior of PC/FA composites was characterized by parallel plate rheometer system. Addition of treated FA imparted dimensional and thermal stability, which has been observed in scanning electron micrographs and in thermogravimetric analysis plot. The increase of thermal stability has been explained based on increased mechanical interlocking of PC chains inside the structure of FA. This study shows that surface modification of FA is one of the key factors influencing the mechanical and thermal properties of PC/FA composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Contact engineering for nano‐scale CMOS
Authors: Hussain Muhammad , Fahad Hossain , Qaisi Ramy
Published: September 2012

High performance computation with longer battery lifetime is an essential component in our today's digital electronics oriented life. To achieve these goals, field effect transistors based complementary metal oxide semiconductor play the key role. One of the critical requirements of transistor structure and fabrication is efficient contact engineering. To catch up with high performance information processing, transistors are going through continuous scaling process. However, it also imposes new challenges to integrate good contact materials in a small area. This can be counterproductive as smaller area results in higher contact resistance thus reduced performance for the transistor itself. At the same time, discovery of new one or two‐dimensional materials like nanowire, nanotube, or atomic crystal structure materials, introduces new set of challenges and opportunities. In this paper, we are reviewing them in a synchronized fashion: fundamentals of contact engineering, evolution into non‐planar field effect transistors, opportunities and challenges with one and two‐dimensional materials and a new opportunity of contact engineering from device architecture perspective.
Electron and hole energy relaxation rates in GaInNAs/GaAs quantum wells via deformation potential and piezoelectric scattering
Authors: Tiras Engin , Ardali Sukru
Published: September 2012

The two‐dimensional (2D) electron and hole energy relaxation associated with acoustic phonon emission in n‐ and p‐type modulation doped Ga0.7In0.3NyAs1–y/GaAs quantum wells has been investigated experimentally using Shubnikov‐de Haas (SdH) effect measurements performed as a function of lattice temperature and applied electric field. Nitrogen concentration dependence of the effective mass and quantum lifetime of the 2D electrons in the n‐type samples have been determined from the temperature and magnetic field dependencies of the amplitude of SdH oscillations, respectively. The in‐plane effective mass of the 2D electrons increases when the nitrogen mole fraction is increased from y = 0.004 to 0.010 but remains the same when it is increased to y = 0.015. The values obtained for quantum lifetime suggest that interface roughness is the dominating scattering mechanism in n‐type Ga0.7In0.3NyAs1–y/GaAs quantum wells. The electron temperature (Te) of hot electrons and the hole temperature (Th) of hot holes have been obtained from the lattice temperature (TL) and applied electric field dependencies of amplitude of SdH oscillations. The experimental results for the electron/hole temperature dependence of power loss are compared with the current theoretical models for power loss in 2D semiconductors, which include both piezoelectric and deformation‐potential scattering. For n‐type samples, the power loss from the electrons is found to be proportional to (T–T) with γ in the range from 3.48 to 4.66, indicating that the energy relaxation of electrons is due to acoustic phonon emission via unscreened piezoelectric interaction. For the p‐type sample, the power loss is approximately proportional to (T–T). This behavior is in accord with the theoretical predictions for the variation of power loss with hole temperature for a 2D hole gas in the equipartition regime.
Optical properties of erbium doped antimony based glasses: Promising visible and infrared amplifiers materials
Authors: Hamzaoui M. , Soltani M. T. , Baazouzi M. , Tioua B. , Ivanova Z. G. , Lebullenger R. , Poulain M. , Zavadil J.
Published: September 2012

Highly stable glasses in the (70 − x)Sb2O320Na2O10ZnOxEr2O3 (x = 0.25, 0.5, and 1.0 mol%) system have been prepared and investigated by UV–Vis–NIR absorption, near infrared photoluminescence and time‐resolved spectroscopy. Judd–Ofelt study has been used to determine the intensity parameters (Ω2, Ω4, and Ω6), spontaneous emission probabilities, branching ratios, and radiative lifetimes (τR) related to the corresponding optical transitions of Er3+ ions. Details of the emission at ∼1530 nm and spectroscopic characteristics such as the stimulated emission cross‐section (σe), effectiveband width (Δλeff), quantum efficiency, and the optical gain have been summarized, accounting the role of the increased Er content. The obtained results indicate that these new low phonon energy glasses could be used as a laser medium and for optical amplification in the 1.5 µm region. In particular, the composition containing 0.5 mol% Er2O3 exhibits optimal values of Ω2 (4.5 × 10−20 cm2), Δλeff = 57 nm, σe = 7.28 × 10−21 cm2, τmeas (3.36 ms), and quantum efficiency of the 4I13/2 level of Er3+ ions ∼71%.
Polarization phenomena in light emission from C‐plane Al(In)GaN heterostructures
Authors: Durnev M. V. , Karpov S. Yu.
Published: September 2012

The polarization degree and emission pattern anisotropy of light emitted from strained (0001)Al(In)GaN heterostructures are studied by modelling. The model considers accurately the nonparabolicity of heavy, light, and split‐off hole bands, the relevant modification of their densities of states, as well as the optical matrix element dispersion in the k‐space. Accounting for all the above factors provides good agreement of the theoretical predictions with the data reported for both bulk AlGaN alloys grown on sapphire substrates and UV LED structures with Al(In)GaN quantum wells serving as the active regions of the devices. The band‐structure modification in Al(In)GaN materials under variation of their composition and elastic strain are found to be the primary factors controlling the polarization degree and emission patterns of TE‐ and TM‐polarized light. The anisotropy of the TM‐polarized emission pattern (dependence of the emission intensity on the direction of photon release) and polarization degree of the emitted light are found to be remarkably influenced by the nonparabolicity of the hole bands.

magnified image

Comparison of the experimental polarization degrees (symbols) with the theoretical ones (lines) calculated for different in‐plane strains in light‐emitting Al(In)GaN heterostructures.
A Novel Heat Treatment for Excavator Dipper Teeth Manufactured from Low‐Carbon Low‐Alloy Steel
Authors: Zhao Ming‐Chun , Li Jing‐Li , Zhao Ying‐Chao , Huang Xiao‐Fang , Li Jin‐Zhu , Atrens Andrej
Published: September 2012

This research examined the metallurgy of production of forged excavator teeth manufactured from low‐carbon low alloy steel. A novel partial forging‐remnant‐heat hardening technology was proposed. The critical temperature of isothermal annealing for 40 Cr steel was determined experimentally to be 650°C. Production dipper teeth were produced using this novel technology. Their properties were compared with dipper teeth produced by the alternative routes. The novel technology provided optimum microstructure, good mechanical properties, and a lower economical cost, congruent with the low carbon economy.
Evolution of homeobox genes
Authors: Holland Peter W. H.
Published: September 2012

Many homeobox genes encode transcription factors with regulatory roles in animal and plant development. Homeobox genes are found in almost all eukaryotes, and have diversified into 11 gene classes and over 100 gene families in animal evolution, and 10 to 14 gene classes in plants. The largest group in animals is the ANTP class which includes the well‐known Hox genes, plus other genes implicated in development including ParaHox (Cdx, Xlox, Gsx), Evx, Dlx, En, NK4, NK3, Msx, and Nanog. Genomic data suggest that the ANTP class diversified by extensive tandem duplication to generate a large array of genes, including an NK gene cluster and a hypothetical ProtoHox gene cluster that duplicated to generate Hox and ParaHox genes. Expression and functional data suggest that NK, Hox, and ParaHox gene clusters acquired distinct roles in patterning the mesoderm, nervous system, and gut. The PRD class is also diverse and includes Pax2/5/8, Pax3/7, Pax4/6, Gsc, Hesx, Otx, Otp, and Pitx genes. PRD genes are not generally arranged in ancient genomic clusters, although the Dux, Obox, and Rhox gene clusters arose in mammalian evolution as did several non‐clustered PRD genes. Tandem duplication and genome duplication expanded the number of homeobox genes, possibly contributing to the evolution of developmental complexity, but homeobox gene loss must not be ignored. Evolutionary changes to homeobox gene expression have also been documented, including Hox gene expression patterns shifting in concert with segmental diversification in vertebrates and crustaceans, and deletion of a Pitx1 gene enhancer in pelvic‐reduced sticklebacks. WIREs Dev Biol 2013, 2:31–45. doi: 10.1002/wdev.78

This article is categorized under:

Gene Expression and Transcriptional Hierarchies > Gene Networks and Genomics

Early Embryonic Development > Development to the Basic Body Plan

Comparative Development and Evolution > Body Plan Evolution
Hydrolysis and fermentation for cellulosic ethanol production
Authors: Xiros Charilaos , Topakas Evangelos , Christakopoulos Paul
Published: September 2012

Second‐generation bioethanol produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, has the potential to be a valuable substitute for, or a complement to, gasoline. At least three major factors—rapidly increasing atmospheric CO2 levels, dwindling fossil fuel reserves, and their rising costs—suggest that we now need to accelerate research plans to make greater use of plant‐based biomass for energy production and as a chemical feedstock as part of a sustainable energy economy. Optimizing the production of bioethanol to be competitive with petrochemical fuels is the main challenge for the underlying process development. The exhaustive research on enzyme technology during the latest years, resulting in significant advances in the field, show the importance of the enzymatic hydrolysis for a profitable ethanol production process. On the other hand, the persisting challenges in biomass pretreatment, which are the initial steps in most process designs, show the remarkable recalcitrance of the lignocellulosic materials to biological degradation. The recent scientific trends show toward an integrated overall bioconversion process in which fermentation technology and genetic engineering of ethanologenic microorganisms aim not only at maximizing yields and productivities but also at widening the range of fermentation products and applications.

This article is categorized under:

Bioenergy > Science and Materials
DNA‐based programing of quantum dot properties
Authors: Ma Nan , Kelley Shana O.
Published: September 2012

Nucleic acid molecules can serve as robust ligands for aqueous synthesis of semiconductor nanocrystals or quantum dots (QDs). QD properties including size, morphology, dispersity, emission maximum, and quantum yield are highly dependent on the sequences and structures of nucleic acids used for the synthesis. This synthetic strategy provides a novel facile means of constructing compact, stable, and biofunctionalized QDs in one step, which is of particular interest for a variety of applications such as biosensing, bioimaging, and self‐assembly. This article summarizes recent advances in nucleic acid‐templated QD synthesis with an emphasis on the nucleic acids‐based programing of quantum dots properties. A variety of applications based on DNA‐passivated QDs are also discussed. WIREs Nanomed Nanobiotechnol 2013, 5:86–95. doi: 10.1002/wnan.1191

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Attempted Integration of Multiple Species of Turaco Into a Mixed‐Species Aviary
Authors: Valuska Annie J. , Leighty Katherine A. , Ferrie Gina M. , Nichols Valerie D. , Tybor Cheryl L. , Plassé Chelle , Bettinger Tamara L.
Published: September 2012

Mixed‐species exhibits offer a variety of benefits but can be challenging to maintain due to difficulty in managing interspecific interactions. This is particularly true when little has been documented on the behavior of the species being mixed. This was the case when we attempted to house three species of turaco (family: Musophagidae) together with other species in a walk‐through aviary. To learn more about the behavior of great blue turacos, violaceous turacos, and white‐bellied gray go‐away birds, we supplemented opportunistic keeper observations with systematic data collection on their behavior, location, distance from other birds, and visibility to visitors. Keepers reported high levels of aggression among turacos, usually initiated by a go‐away bird or a violaceous turaco. Most aggression occurred during feedings or when pairs were defending nest sites. Attempts to reduce aggression by temporarily removing birds to holding areas and reintroducing them days later were ineffective. Systematic data collection revealed increased social behavior, including aggression, during breeding season in the violaceous turacos, as well as greater location fidelity. These behavioral cues may be useful in predicting breeding behavior in the future. Ultimately, we were only able to house three species of turaco together for a short time, and prohibitively high levels of conflict occurred when pairs were breeding. We conclude that mixing these three turaco species is challenging and may not be the most appropriate housing situation for them, particularly during breeding season. However, changes in turaco species composition, sex composition, or exhibit design may result in more compatible mixed‐turaco species groups. Zoo Biol. 32:216–221, 2013. © 2012 Wiley Periodicals, Inc.
Quantification of Microcrack Anisotropy in Quartzite – A Comparison between Experimentally Undeformed and Deformed Samples
Authors: Mamtani Manish A. , Vishnu C. S. , Basu Arindam
Published: September 2012

In this paper, microcrack patterns in a quartzite are quantified using fractal geometry based methods. Since the quartzite does not show a mesoscopic foliation, the fabric was recognized using anisotropy of magnetic susceptibility (AMS) analysis. Microcracks were investigated in thin sections prepared along the three principal planes of the AMS ellipsoid. Point load tests were performed on cores drilled parallel as well as perpendicular to the magnetic foliation. After experimental deformation, thin sections were prepared in two orientations – (a) parallel to the plane of failure (i.e., parallel to the direction of loading), (b) perpendicular to the plane of failure (i.e., perpendicular to the direction of loading), and microcrack patterns in these sections were investigated. The box-counting method of fractal analysis was first applied to microcracks traced from SEM images from each thin section of the experimentally undeformed as well as deformed samples to establish the fractal nature of the microcrack pattern. It was found that in thin sections perpendicular to the direction of loading, the box (fractal) dimension tends to marginally increase. This is inferred as a manifestation of the increase in complexity of the pattern. The software AMOCADO, which is based on the modified Cantor Dust method of fractal analysis, was applied to microcrack pattern from each thin section in order to quantify the pattern anisotropy. It is noted that the anisotropy significantly reduces in sections perpendicular to the loading direction. SEM data are presented to demonstrate that this reduction in anisotropy is on account of generation and/or growth of new cracks in random orientations. It is envisaged that the approach adopted in this investigation maybe useful in rock mechanics and mineral-resource applications in future.
Geochemistry and Tectonic Setting of Tuting Metavolcanic Rocks of Possible Ophiolitic Affinity from Eastern Himalayan Syntaxis
Authors: Saha Puspendu , Acharyya S.K. , Balaram V. , Roy Parijat
Published: September 2012

Geochemistry of Tuting metavolcanic rocks is being reported for the first time. Narrow slivers of mafic volcanic rocks, as those at Tuting, also occur in close association with slivers of more complete sections of ophiolites at the Tsangpo river section upstream of Tuting and skirt round the Namche Barwa antiform. These detached slivers of the mafic volcanic rocks and the ophiolites represent the easternmost components of the Yarlung Tsangpo Ophiolite, and also define the arcuate shape of the Eastern Himalayan syntaxis. The metavolcanic rocks exposed at the apex of the Siang river dome at Tuting (Tsangpo River named Siang down stream of Tuting) is the only exposure of such rocks from the Himalayan syntaxial area in India.

The Tuting metavolcanic rocks correspond to andesite and basaltic andesite as per TAS diagram. The mobility of major elements possibly has affected their classification. As per Zr/TiO2 – Nb/Y diagram of Winchester and Floyd (1977), proposed for classification of altered igneous rocks, the Tuting samples mainly correspond to ‘sub-akaline basalt’ and one sample plot as ‘andesite/basalt’. These have a flat chrondrite-normalised REE pattern. MORB-normalized multi-elemental plot shows enrichment in large ion lithophile (LIL) and the light rare earth elements (LREE), and depletion in several high field strength elements (HFSE). Based on these trace element patterns and a few discrimination plots, the Tuting metavolcanic rocks are inferred to have generated in supra-subduction zone environment in an intra-oceanic arc, back arc setting, or in a mid-ocean ridge process that resembles the Chile Ridge spreading centre.
Coralline Algae from the Aramda Reef Member of the Chaya Formation, Mithapur, Gujarat
Authors: Kishore S. , Misra P. K. , Pandey D. K. , Jauhri A. K. , Bahadur Tej , Singh S. K. , Chauhan R.S. , Tripathi S. K.
Published: September 2012

The Quaternary sediments of the Aramda Reef Member of the Chaya Formation exposed in the Mojap coast near Mithapur, Gujarat are characterized by well-developed coralline algal build-ups. These algal build-ups are exceptionally rich in coralline algae and corals. In the present paper, thirteen species belonging to eight genera of coralline algae are described. Out of these, seven species (Titanoderma nataliae, Lithophyllum nitorum, Lithophyllum quadratum, Spongites sp. Brandano et al., 2005, Sporolithon lvovicum, Mesophyllum fructiferum and Lithothamnion praefruticulosum) are the new records for India. Four species (Titanoderma pustulatum, Sporolithon intermedium, Mesophyllum commune and Phymatolithon sp.) are first time recorded from the study area. Among the major framework builders of coralline algae of the Aramda Reef Member are Lithophyllum, Titanoderma, Sporolithon, Mesophyllum and Lithothamnion.

Two associations of the coralline algal assemblages can be distinguished: one indicating shallow water, high-energy conditions is developed in the upper part, while the other suggesting deposition in low-energy conditions is characteristic of the lower part of the succession. These algal associations, together with their growth-forms (encrusting, warty to fruticose, layered) come from stratigraphically separate beds. They indicate that the temperature, depth and hydrodynamic energy conditions also fluctuated during deposition of the Aramda Reef Member. It is concluded that the lower Hapalidiaceae-Sporolithaceae association dominated during warmer interval, whereas the upper lithophylloids association flourished in relatively low-temperature conditions. The associated corals indicate that minimum winter sea surface temperature remained above 18°-20° C.
Aeromagnetic Data Analysis of the Southern Aravalli Fold Belt: Its Implications in Understanding the Inter-relationship Among the Migmatites and Gneissic Rocks, Aravalli Supracrustals and Godhra Granite
Authors: Sahu B. K.
Published: September 2012

The Southern Aravalli Fold Belt represents a geologically complex terrain comprising migmatites, gneisses, low-grade metasediments and intrusive granites. Processing and interpretation of the existing aeromagnetic data using modern techniques has helped in understanding the geological complexity of the area. High quality aeromagnetic maps – total intensity, vertical derivative, analytic signal and 3D Euler depth – have been produced from the digitally processed data to augment visualisation and interpretation of the data. Strong east-west to northeast-southwest long strike-length anomalies in the southern part within the gneissic/granitic terrain indicate presence of narrow bands of high-susceptibility (magnetic) materials probably along regional lineaments. The thick sequence (> 1 km) of magnetically transparent sedimentary cover in the Rajgad basin is better visualised in the analytic signal and Euler Depth maps. The sediments in the northern part of the basin are deposited in a grabben formed by a northwest-southeast trending marginal fault in the north and an intrabasinal east-west fault in the south as demonstrated in the Euler 3D map. The Lunavada and Champaner Groups are separated by a shear zone comprising en-echelon shears clearly indicated in the shaded relief and vertical derivative maps. Interpretation of magnetic relief of the aeromagnetic data reveals that the area comprises of five distinct litho-tectonic units. This study demonstrates that the old aeromagnetic data acquired few decades back can provide valuable geological information, if processed using modern techniques.