An XRD, FTIR and TPD Investigation of NO2 Surface Adsorption Sites of δ, γ Al2O3 and Barium Supported δ, γ Al2O3

In this paper an XRD, FTIR and TPD investigation of NO₂ surface adsorption sites of , Al₂O₃ and barium supported , Al₂O₃ is reported. Aim of this study is to bring additional light on the surface structures involved in NOx adsorption. Two samples of barium supported aluminas have been prepared and aged at 800 °C. These samples were characterised in comparison with the relative alumina support. The XRD characterisation of these samples shows the presence of barium carbonate and barium aluminate supported on alumina. The comparison of the FTIR spectra, before and after NO₂ adsorption, has revealed the formation, upon NO₂ contact, of a complex variety of nitrate and nitrite groups. The thermal desorption of nitrate and nitrite species has been simultaneously studied by means of FTIR spectroscopy and by TPD technique. By comparing the structural, adsorptive and spectroscopic results obtained on alumina and on barium supported alumina samples, a hypothesis on the basic sites active in NO₂ adsorption and of the possible decomposition paths induced by thermal heating are proposed.     

Studies of the interface between indium and beta/beta″ alumina tubes

The anodic degradation of a beta/beta″ alumina electrolyte in contact with liquid indium was studied by voltammetric techniques at 35°C. The electrolyte tubes were found to crack when the anodic current reaches about 4 mA cm⁻², referred to the apparent surface area. Simultaneously, a passivation occurred which is attributed to film formation on indium in contact with the molten nitrate through the cracks. Transmission electron micrographs taken before and after the anodic cycle yielded information on how the degradation may proceed. At the cathodic side of the electroactive domain of the solid electrolyte, the process of sodium dissolution in the indium at lower voltages and the formation of indium-sodium compounds at larger voltages can be distinguished.     

An investigation of the interface between graphite and beta/beta″ alumina

The anodic degradation of beta/beta″ alumina of different compositions was investigated by voltammetric techniques in cells of the type Cu/Rodar alloy/carbon fibers/graphite layer/solid electrolyte/NaNO₃/Pt/Cu at 350°C. The possibility was evaluated if the voltammetric results are useful as a diagnostic tool for the prediction of the failure of beta/beta″ alumina electrolytes in sodium sulfur cells. Single voltage sweeps were applied into the anodic and also the cathodic direction at relatively low sweep rates (0.1-100mV s⁻¹), starting at the open circuirt voltage and extending to different voltages of reversal. The anodic current-voltage curves display a continuous rise of current with voltage up to 4.5 V, vs a Na reference electrode, followed by a gradual decrease afterwards. The anodic current is mainly attributed to the formation of sodium carbonate and carbon monoxide. The oxygen is supplied by the degradation of the solid electrolyte. The cathodic current-voltage curves reveal the intercalation of sodium into the graphite Structural studies of specimens from the solid electrolyte were carried out by electron microscopy before and after the electrochemical runs. They yielded information on how the anodic degradation proceeds with time.     

Green leaf manuring with prunings of Leucaena leucocephala for nitrogen economy and improved productivity of maize (Zea mays)–wheat (Triticum aestivum) cropping system

Green leaf manuring with prunings of Leucaena leucocephala is regarded as a useful source of N to plants but the actual substitution of N fertilizer, release and recovery of N as well as effects on soil fertility are not adequately studied. The present studies investigated the effect of sole and combined use of Leucaena prunings and urea N fertilizer in different proportions on productivity, profitability, N uptake and balance in maize (Zea mays)–wheat (Triticum aestivum) cropping system at New Delhi during 2002–2003 and 2003–2004. Varying quantities of Leucaena green leaf biomass containing 3.83–4.25% N (18.2–20.5 C:N ratio) were applied to provide 0, 25, 50, 75 and 100% of recommended N (120 kg ha⁻¹) to both maize and wheat before sowing. In general, direct application of urea N increased the productivity of both crops more than Leucaena green leaf manure, but the reverse was true for the residual effect of these sources. The productivity of maize increased progressively with increasing proportions of N through urea fertilizer and was 2.41–2.52 t ha⁻¹ with 60 kg N ha⁻¹ each applied through Leucaena and urea, which was at par with that obtained with 120 kg N ha⁻¹ through urea alone (2.56–2.74 t ha⁻¹). Similarly, wheat yield was also near maximum (4.46–5.11 t ha⁻¹) when equal amounts of N were substituted through Leucaena and urea. Residual effects were obtained on the following crops and were significant when greater quantity of N (>50%) was substituted through Leucaena. Nitrogen uptake and recovery were also maximum with urea N alone, and N recovery was higher in maize (33.4–42.1%) than in wheat (27.3–29.8%). However, recovery of residual N in the following crop was more from Leucaena N alone (8.5–10.3%) than from urea fertilizer (1.7–3.8%). Residual soil fertility in terms of organic C and KMnO₄ oxidizable N showed improvement with addition of Leucaena prunings, which led to a positive N balance at the end of second cropping cycle. Net returns were considerably higher with wheat than with maize, and were comparatively lower with greater proportion of Leucaena because of its higher cost. Nonetheless, it was beneficial to apply Leucaena and urea on equal N basis for higher productivity and sustainability of this cereal-based cropping system.     

Phase separation and crystallization in glasses of the lithium silicate system xLi2O · (100 ? x)SiO2 (x = 23.4, 26.0, 33.5)

The phase separation in ultimately homogenized glasses of the lithium silicate system xLi₂O · (100 − x)SiO₂ (where x = 23.4, 26.0, and 33.5 mol % Li₂O) has been investigated. The glasses of these compositions have been homogenized using the previously established special temperature-time conditions, which provide the maximum dehydration and the removal of bubbles from the glass melt. The parameters of nucleation and growth of phase_separated inhomogeneities and homogeneous crystal nucleation have been determined. The absolute values of the stationary nucleation rates I _st of lithium disilicate crystals in the 23.4Li₂O · 76.6SiO₂ and 26Li₂O · 74SiO₂ glasses with the compositions lying in the metastable phase separation region have been compared with the corresponding rates I _st for the glass of the stoichiometric lithium disilicate composition. It has been established that the crystal growth rate have a tendency toward a monotonic increase with an increase in the temperature, whereas the dependences of the crystal growth rate on the time of low-temperature heat treatment exhibit an oscillatory behavior with a monotonic decrease in the absolute value of oscillations. The character of crystallization in glasses with the compositions lying in the phase separation region of the Li₂O-SiO₂ system is compared with that in the glass of the stoichiometric lithium disilicate composition. The inference has been made that the phase separation weakly affects the nucleation parameters of lithium disilicate and has a strong effect on the crystal growth.     

Ionic conductivity of (As2Se3)1 ? x(AgHal)x (Hal = I, Br) nanocomposites

Nanocomposites based on chalcogenide glasses have been synthesized. A differential thermal analysis of (As₂Se₃)_{1 − x} (AgI) _x and (As₂Se₃)_{1 − x} (AgBr)x (0 ≤ x ≤ 0.5) samples has been performed. The size of nanofragments that undergo elementary structural transformations has been evaluated. The data obtained are in agreement with the evaluated sizes of X-ray coherent scattering regions. The electrical properties of the glasses under consideration have been studied using impedance spectroscopy in the temperature range 293–393 K. It has been demonstrated that the ionic component of the electrical conductivity dominates in glasses with a high content of silver halide.     

Photoelectrical properties of the system ITO/poly(4,4″-dipenthoxy-3′-dodecyl-2,2′:5′,2″-terthiophene)/Al: Effect of electrosynthesis conditions

The photoelectrical properties of the system ITO/poly(4,4-dipenthoxy-3-dodecyl-2,2:5,2-terthiophene)/aluminium are strongly dependent on the electrochemical preparation parameters of the polymer. In particular the polymerization temperature has a significant influence on the photoelectronic characteristics of polymer. The best properties were attained with polymers prepared at higher temperatures (32–40 °C).     

Φ250/Φ150双复合挤出生产线

Φ2 5 0 /Φ15 0双复合挤出生产线为背叠式结构 ,采用Proface触摸屏作人机界面 ,主要用于生产全钢载重子午线轮胎胎面 ,最大挤出宽度为 5 0 0mm ,生产速度为 3～ 3 0m·min- 1 。该生产线的安装采用一次浇灌机头底板地脚螺栓、紧固后组装主机、再二次浇灌的方法 ,可消除机头较重带来的安全隐患 ,并缩短安装调试时间。     

A study of the formation of Ln2 + xMe2 ? xO7 ? x/2 (Ln = Gd, Dy; Me = Zr, Hf) nanocrystals

It has been established that the process of producing the Ln_{2 + x} Me_{2 − x} O_{7 − x/2} (Ln = Gd, Dy; Me = Zr, Hf) nanocrystals by calcination of hydroxides, which, in turn, have been produced by coprecipitation of metal salts, includes several stages. At the beginning, the X-ray amorphous structure of the precursors remains unchanged during dehydration; during subsequent heating to 600–700°C, nanocrystals with a disordered fluorite structure begin to be formed. An increase in the temperature above 700°C leads to an increase in the size of crystallites (coherent scattering regions). This process is accompanied by changes occurring in their local structure. In the nanocrystalline powders of Cd₂Hf₂O₇ and Gd₂Zr₂O₇ synthesized at 1200°C (6 h), the pyrochlore-type superstructure with the lattice parameters doubled relative to fluorite has been revealed. It has also been found that, possibly, the Dy₂HfO₅ sample at 1600°C (3 h) has a modulated structure.     

High production of butyric acid by Clostridium tyrobutyricum mutant? ?

The objective of this study was to improve the production of butyric acid by process optimization using the metabolically engineered mutant of Clostridium tyrobutyricum (PAK-Em). First, the free-cell fermentation at pH 6.0 produced butyric acid with concentration of 38.44 g/L and yield of 0.42 g/g. Second, the immobilized-cell fermentations using fibrous-bed bioreactor (FBB) were run at pHs of 5.0, 5.5, 6.0, 6.5 and 7.0 to optimize fermentation process and improve the butyric acid production. It was found that the highest titer of butyric acid, 63.02 g/L, was achieved at pH 6.5. Finally, the metabolic flux balance analysis was performed to investigate the carbon rebalance in C. tyrobutyricum. The results show both gene manipulation and fermentation pH change redistribute carbon between biomass, acetic acid and butyric acid. This study demonstrated that high butyric acid production could be obtained by integrating metabolic engineering and fermentation process optimization.     

A Novel Method to Fabricate Silicon Nanowire p–n Junctions by a Combination of Ion Implantation and in-situ Doping

We demonstrate a novel method to fabricate an axial p–n junction inside <111> oriented short vertical silicon nanowires grown by molecular beam epitaxy by combining ion implantation with in-situ doping. The lower halves of the nanowires were doped in-situ with boron (concentration ~10¹⁸ cm⁻³), while the upper halves were doubly implanted with phosphorus to yield a uniform concentration of 2 × 10¹⁹ cm⁻³. Electrical measurements of individually contacted nanowires showed excellent diode characteristics and ideality factors close to 2. We think that this value of ideality factors arises out of a high rate of carrier recombination through surface states in the native oxide covering the nanowires.     

Preparation, electrochemical properties, and cycle mechanism of Li1? x Fe0.8Ni0.2O2-Li x MnO2 (Mn/(Fe+Ni+Mn)=0.8) material

A new type of Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ (Mn/(Fe+Ni+Mn)=0.8) material was synthesized at 350 °C in an air atmosphere by a solid-state reaction. The material had an XRD pattern that closely resembled that of the original Li_1−x FeO₂-Li _x MnO₂ ((Fe+Ni+Mn)=0.8) with much reduced impurity peaks. It was composed of many large particles of about 500–600 nm and small particles of about 100–200 nm, which were distributed among the larger particles. The Li/Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ cell showed a high initial discharge capacity above 192 mAh/g, which was higher than that of the parent Li/Li_1−x FeO₂-Li _x MnO₂ (186 mAh/g). This cell exhibited not only a typical voltage plateau in the 2.8 V region, but also an excellent cycle retention rate (96%) up to 45 cycles. We suggest a unique role of doped nickel ion in the Li/Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ cell, which results in the increased initial discharge capacity from the redox reaction of Ni²⁺/Ni³⁺ between 2.0 and 1.5 V region.     

One Dimensional Coordination Polymer of Nickel(II)-Squarate with N,N,N′,N′-tetramethylethylenediamine, {[Ni(μ-sq)(H2O)2(tmen)]·H2O}n

A novel 1D coordination polymer {[Ni(μ-sq)(H₂O)₂(tmen)]·H₂O}_n (H₂sq = squaric acid and tmen = N,N,N′,N′ -tetramethylethylenediamine) has been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV-vis.) and magnetic susceptibility are reported. The structure of the complex consists of the bidentate tmen ligand bound to Ni(II) center and a bridging squarate in the 1,3-bonding mode. The distorted octahedral geometry of Ni(II) is completed by two aqua ligands. The structure contains chains of squarato-O ¹ ,O ³ -bridged polynuclear nickel(II) units held together by intermolecular hydrogen bonds interactions between water molecules and oxygen atoms of squarate ligand forming a novel R6 motif.     

Synthesis and characterization of 5?V LiCoxNiyMn2?x?yO4 (x?=?y?=?0.25) cathode materials for use in rechargeable lithium batteries

Double doped spinel LiCo _x Ni _y Mn_2−x−y O₄ (x = y = 0.25) have been synthesised via sol–gel method using different chelating agents viz., acetic acid, maleic acid and oxalic acid to obtain 5 V positive electrode material for use in lithium rechargeable batteries. The sol–gel route endows lower processing temperature, lesser synthesis time, high purity, better homogeneity, good control of particle size and surface morphology. Physical characterizations of the synthesized powder were carried out using thermo-gravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The electrochemical behaviour of the calcined samples has been carried out by galvanostatic charge/discharge cycling studies in the voltage range 3–5 V. The XRD patterns reveal crystalline single-phase spinel product. SEM photographs indicate micron sized particles with good agglomeration. The charge–discharge studies show LiCo_0.25Ni_0.25Mn_1.5O₄ synthesized using oxalic acid to be as a promising cathode material as compared to other two chelating agents and delivers average discharge capacity of 110 mA h g⁻¹ with low capacity fade of 0.2 mA h g⁻¹ per cycle over the investigated 15 cycles.     

Atomistic characterization of binding modes and affinity of peptide inhibitors to amyloid-β protein

The aggregation of amyloid β-protein (Aβ) is tightly linked to the pathogenesis of Alzheimer’s disease. Previous studies have found that three peptide inhibitors (i.e., KLVFF, VVIA, and LPFFD) can inhibit Aβ aggregation and alleviate Aβ-induced neurotoxicity. However, atomic details of binding modes and binding affinities between these peptide inhibitors and Aβ have not been revealed. Here, using molecular dynamics simulations and molecular mechanics Poisson Boltzmann surface area (MM/PBSA) analysis, we examined the effect of three peptide inhibitors (KLVFF, VVIA, and LPFFD) on their sequence-specific interactions with Aβ and the molecular basis of their inhibition. All inhibitors exhibit varied binding affinity to Aβ, in which KLVFF has the highest binding affinity, whereas LPFFD has the least. MM/PBSA analysis further revealed that different peptide inhibitors have different modes of interaction with Aβ, consequently hotspot binding residues, and underlying driving forces. Specific residue-based interactions between inhibitors and Aβ were determined and compared for illustrating different binding and inhibition mechanisms. This work provides structure-based binding information for further modification and optimization of these three peptide inhibitors to enhance their binding and inhibitory abilities against Aβ aggregation.     

51/2″钻杆用旋转总成的研制

针对现有旋转防喷器的旋转总成通径均为Ф180mm左右,无法与51/2″钻杆配套应用的问题开展研究。完成了51/2″钻杆用旋转总成连接单元、外部壳体固定单元及旋转密封单元的设计等三项研究内容。该总成与现有旋转防喷器壳体及液压站完全兼容,达到额定动压10.5MPa,额定静压21MPa,适应转速100rpm的技术指标。创新的设计了花键传扭和螺环压紧机构的新型组合连接单元,代替原有螺钉连接机构。在具备较高强度的同时,将总成通径由φ180mm扩大至φ197mm,扩展了设备的应用范围。该设备在徐深8-更平1井进行了现场试验,保证了该井的井口安全控制,取得了良好的应用效果。     

51/2″套管开窗侧钻井打捞工具应用

套管开窗侧钻工艺落鱼事故处理因井眼间隙小和工具选择范围窄处理比较困难,应用设计的(C) 95mm螺杆打捞筒、(C) 80mm穿心打捞筒的小尺寸打捞工具,解决了开窗侧钻施工中打捞特殊落鱼的事故,为51/2"套管开窗侧钻井提供有力保障.     

EPR study of solid solutions La1 ? 0.33yBa0.33yMnyAl1 ? yO3 (y = 0.02, 0.04, 0.10)

Solid solutions La_{1 − 0.33y} Ba_0.33y Mn _y Al_{1 − y} O₃ (y = 0.02, 0.04, 0.10) prepared using the ceramic technique have been investigated by the EPR method at temperatures of 77 and 300 K. By comparing with the calculated spectra, the experimental spectra have been assigned to Mn²⁺ ions (g = 2.04 and line width ΔH _pp = 64 × 10⁻⁴ T at T = 77K) and Mn⁴⁺ ions (g = 1.97 and ΔH _pp = 76 × 10⁻⁴ T at T = 77 K) and the broad line (ΔH _pp = 500 × 10⁻⁴ T at T = 77 K) has been attributed to clusters. The dilution of manganese ions as a result of the dissolution of La_0.67Ba_0.33MnO₃ in LaAlO₃ has allowed one to trace the cluster formation and the spin dynamics of Mn ions. It has been established that, at room temperature, compared to the system in which the Sr²⁺ ion with a smaller ionic radius is the replacing element, the localized states are more stable at all three manganese concentrations (the EPR lines are more intense). The La_0.67Ba_0.33MnO₃ clusters dissolved in LaAlO₃ retain some properties of a concentrated compound even upon dilution to y = 0.02.     

Electrochemical behaviour of FexCo3?xO4 with (x?=?0, 1, 2 and 3) oxides thin film electrodes in alkaline medium

Spinel-type Fe _x Co_3−x O₄ thin films with x = 0, 1, 2 and 3 were prepared, on stainless steel supports, using the thermal decomposition method at 400 °C. The X-ray diffraction patterns show the presence of a spinel-type structure with a low crystallinity. The electrochemical behaviour was investigated in 1 M KOH, using open-circuit-potential measurements and cyclic voltammetry. The studies allowed to observe the redox reactions occurring at the Fe _x Co_3−x O₄ (x = 1 and 2) oxide surface, namely Fe₃O₄/Fe(OH)₂ or Fe₃O₄/Fe₂O₃, Co₃O₄/CoOOH, Co(OH)₂/CoOOH and CoO₂/CoOOH by comparing the experimental data with those obtained for the Co₃O₄ and Fe₃O₄ films as well as with those referred to in the literature. The results show that iron ions play the major role in the solid-state surface redox transitions in the negative potential range, whereas the cobalt ions are the key species in the positive potential range. However, the contribution of each component, although small, has to be considered in both potential regions.     

转动型φ1800×H1600橡胶护舷的研究

转动型φ1800×H1600橡胶护舷的研究