The glass transition and crystallization kinetic studies on BaNaB9O15 glasses

Transparent glasses of BaNaB9O15 (BNBO) were fabricated via the conventional melt-quenching technique. The amorphous and the glassy nature of the as-quenched samples were respectively, confirmed by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). The glass transition and crystallization parameters were evaluated under non-isothermal conditions using DSC. The correlation between the heating rate dependent glass transition and the crystallization temperatures was discussed and deduced the Kauzmann temperature for BNBO glass-plates and powdered samples. The values of the Kauzmann temperature for the plates and powdered samples were 776 K and 768 K, respectively. Approximation-free method was used to evaluate the crystallization kinetic parameters for the BNBO glass samples. The effect of the sample thickness on the crystallization kinetics of BNBO glasses was also investigated.Comment: 23 pages, 12 figure

HYDROGEN BONDING IN betabeta-NITRO ALCOHOLS. III. PYRIDINE COMPLEXES

BETA -Nitro alcohols form stable 1:1 complexes with pyridine, examples of which were prepared. In solvents such as dichloromethane and carbon tetrachloride the complexes partially dissociate into their components. The dissociation constants for the equilibria were determined by infrared methods and may be used as a measure of the strength of the complex hydrogen bond. The dissociation constants decrease with increasing number of BETA -nitro groups. Some reactions of the pyridine complexes are described. (auth

Penapisan Senyawa Fitokimia Dan Pengujian Antioksidan Ekstrak Daun Pohon Merapat

Hutan kerangas merupakan kumpulan vegetasi pohon di hutan hujan tropis, dicirikan antara lain oleh kandungan hara dan keanekaragaman hayati yang rendah, sehingga penggunaan pohonnya menjadi terbatas. Hutan kerangas tersebar luas di Kalimantan (misalnya Kalimantan Selatan). Salah satu jenis pohon yang dapat tumbuh dan berkembang pada kondisi ekstrim adalah merapat (Combretocarpus rotundatus). Daunnya mengandung senyawa kimia tertentu yang mengindikasikan berkemampuan fisiologis menghasilkan bioaktivitas seperti antioksidan. Sebagai konsekuesinya, hal ini diharapkan dapat meningkatkan nilai tambah dari pemanfaatan pohon kerangas. Terkait hal tersebut, pencermatan terhadap kandungan senyawa fitokimia dan pengujian kemampuan antioksidan dilakukan terhadap sampel kering daun merapat yang berasal dari hutan kerangas di Kalimantan Selatan. Awalnya, daun kering diekstrak dengan larutan metanol menghasilkan ekstrak methanol (sampel 1), fraksinasi lanjutan dilakukan dengan kromatografi kolom menggunakan eluent kloroform. Fraksi kloroform yang didapatkan (sampel 2) selanjutnya difraksinasi kembali menggunakan campuran larutan etil asetat-kloroform (dengan proporsi sama), yang menghasilkan sampel 3. Pencermatan fitokimia mengungkapkan bahwa ekstrak metanol mengandung senyawa fitokimia tertentu seperti flavonoid, turunan phenol, hidrokuinon, tanin dan triterpenoid, yang berperan sebagai antioksidan. Ekstrak metanol (sampel 1) menunjukkan aktivitas antioksidan tertinggi dengan memberikan reaksi reduksi terhadap pelepasan radikal bebas oleh Difenil Pikril Hidrazil Hidrat (DPPH) (2,2-diphenyl-1-picrylhydrazyl), walaupun penggunaan dari fraksi kloroform (sampel 2) dan fraksi lanjutan etil asetat-kloroform (sampel 3) sangat rendah. Penghambatan radikal bebas dari DPPH pada tingkat 50% (IC 50) oleh ekstrak metanol terjadi pada konsentrasi 21,823 ppm. Sementara itu, vitamin C dan BHT sebagai kontrol aktivitas antioksidan terbentuk lebih efisien pada konsentrasi di bawah 21,823 ppm (berturut-turut pada konsentrasi 6,738 ppm dan 6,279 ppm). Bagaimanapun, nilai IC 50 tersebut memberikan penjelasan kuat bahwa potensi bioaktivitas ekstrak metanol daun merapat dapat digunakan sebagai antioksidan

Comparison of the transcriptomic "stress response" evoked by antimycin A and oxygen deprivation in saccharomyces cerevisiae

<p>Abstract</p> <p>Background</p> <p>Acute changes in environmental parameters (e.g., O₂, pH, UV, osmolarity, nutrients, etc.) evoke a common transcriptomic response in yeast referred to as the "environmental stress response" (ESR) or "common environmental response" (CER). Why such a diverse array of insults should elicit a common transcriptional response remains enigmatic. Previous functional analyses of the networks involved have found that, in addition to up-regulating those for mitigating the specific stressor, the majority appear to be involved in balancing energetic supply and demand and modulating progression through the cell cycle. Here we compared functional and regulatory aspects of the stress responses elicited by the acute inhibition of respiration with antimycin A and oxygen deprivation under catabolite non-repressed (galactose) conditions.</p> <p>Results</p> <p>Gene network analyses of the transcriptomic responses revealed both treatments result in the transient (10 – 60 min) down-regulation of MBF- and SBF-regulated networks involved in the G1/S transition of the cell cycle as well as Fhl1 and PAC/RRPE-associated networks involved in energetically costly programs of ribosomal biogenesis and protein synthesis. Simultaneously, Msn2/4 networks involved in hexose import/dissimilation, reserve energy regulation, and autophagy were transiently up-regulated. Interestingly, when cells were treated with antimycin A well before experiencing anaerobiosis these networks subsequently failed to respond to oxygen deprivation. These results suggest the transient stress response is elicited by the acute inhibition of respiration and, we postulate, changes in cellular energetics and/or the instantaneous growth rate, not oxygen deprivation <it>per se</it>. After a considerable delay (≥ 1 generation) under anoxia, predictable changes in heme-regulated gene networks (e.g., Hap1, Hap2/3/4/5, Mot3, Rox1 and Upc2) were observed both in the presence and absence of antimycin A.</p> <p>Conclusion</p> <p>This study not only differentiates between the gene networks that respond to respiratory inhibition and those that respond to oxygen deprivation but suggests the function of the ESR or CER is to balance energetic supply/demand and coordinate growth with the cell cycle, whether in response to perturbations that disrupt catabolic pathways or those that require rapidly up-regulating energetically costly programs for combating specific stressors.</p

Characteristics of Manure Harvested from Beef Cattle Feedlots

Open lot cattle production systems present unique challenges for nutrient planning processes. Previous estimates of quantities and characteristics of harvested manure from this type of facility are based upon data from the early 1970s. In addition, harvested manure is impacted by weather, feeding program, season, and pen management decisions. The objectives of this study are to characterize under commercial conditions for open lot beef systems: 1) harvested manure quantities and characteristics; 2) impact of factors such as feeding program, season, and management on harvested manure; and 3) mass balance for nitrogen (N) and phosphorus (P). Data from six commercial feedlots (representing 6,366 head of cattle) suggest that 33% of excreted N (65 g/hd/d) and 91% of excreted P (32 g/hd/d) are harvested as manure on average and that current standard estimates published by ASAE (2005) and NRCS (1992a) overestimate harvested manure N and P. Additionally, significant variation was observed among feedlots. This variation is driven by ration nutrient concentration (P only), pen conditions prior to and during manure harvest (N and P), and management choices relative to use of manure in lot maintenance (N and P). The variation would suggest that nutrient planning estimates for open lots would need to be based upon farm specific data as opposed to typical or standard values. Finally, a pen-based mass nutrient balance for a beef cattle feedlot suggests that pen outputs as finished animal, harvested manure, and nutrient losses represent 31%, 23%, and 47%, respectively, of all pen N inputs and 38%, 57%, and 5%, respectively, of all pen P inputs. Inputs include nutrient content of all animals and feed entering a feedlot pen over a grow-out period

Non-Classical Response from Quench-Cooled Solid Helium Confined in Porous Gold

We have investigated the non-classical response of solid 4He confined in porous gold set to torsional oscillation. When solid helium is grown rapidly, nearly 7% of the solid helium appears to be decoupled from the oscillation below about 200 mK. Dissipation appears at temperatures where the decoupling shows maximum variation. In contrast, the decoupling is substantially reduced in slowly grown solid helium. The dynamic response of solid helium was also studied by imposing a sudden increase in the amplitude of oscillation. Extended relaxation in the resonant period shift, suggesting the emergence of the pinning of low energy excitations, was observed below the onset temperature of the non-classical response. The motion of a dislocation or a glassy solid is restricted in the entangled narrow pores and is not likely responsible for the period shift and long relaxation

Dynamic fiber-optic shape sensing using fiber segment interferometry

Dynamic fiber-optic shape sensing, often also referred to as curvature or bend sensing, is demonstrated using fiber segment interferometry, where chains of fiber segments, separated by broadband Bragg grating reflectors, are interrogated using range-resolved interferometry. In this work, the theory of interferometric curvature sensing using fiber segments is developed in detail, including techniques to infer lateral displacements from the measured differential strain data and methods for directional calibration of the sensor. A proof-of-concept experiment is performed, where four fiber strings, each containing four fiber segments of gauge length 20 cm each, are attached to the opposing sides of a flexible support structure and the resulting differential strain measurements are used to determine the lateral displacements of a 0.8 m cantilever test object in two dimensions. Dynamic tip displacement measurements at 40nm . HZ-0.5 noise levels over a 21 kHz bandwidth demonstrate the suitability of this approach for highly sensitive and cost-effective fiber-optic lateral displacement or vibration measurements

Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method

The scope of this work was the determination of kinetic parameters of the thermal oxidative degradation of a Mediterranean scrub using a hybrid method developed at the laboratory. DSC and TGA were used in this study under air sweeping to record oxidative reactions. Two dominating and overlapped exothermic peaks were recorded in DSC and individualized using an experimental and numerical separation. This first stage allowed obtaining the enthalpy variation of each exothermic phenomenon. In a second time, a model free method was applied on each isolated curve to determine the apparent activation energies. A reactional kinetic scheme was proposed for the global exotherm composed of two independent and consecutive reactions. In fine mean values of enthalpy variation and apparent activation energy previously determined were injected in a model fitting method to obtain the reaction order and the preexponential factor of each oxidative reaction. We plan to use these data in a sub-model to be integrated in a wildland fire spread model

Critical wetting of a class of nonequilibrium interfaces: A mean-field picture

A self-consistent mean-field method is used to study critical wetting transitions under nonequilibrium conditions by analyzing Kardar-Parisi-Zhang (KPZ) interfaces in the presence of a bounding substrate. In the case of positive KPZ nonlinearity a single (Gaussian) regime is found. On the contrary, interfaces corresponding to negative nonlinearities lead to three different regimes of critical behavior for the surface order-parameter: (i) a trivial Gaussian regime, (ii) a weak-fluctuation regime with a trivially located critical point and nontrivial exponents, and (iii) a highly non-trivial strong-fluctuation regime, for which we provide a full solution by finding the zeros of parabolic-cylinder functions. These analytical results are also verified by solving numerically the self-consistent equation in each case. Analogies with and differences from equilibrium critical wetting as well as nonequilibrium complete wetting are also discussed.Comment: 11 pages, 2 figure