Miracle-dz/UniFAR-FTUs huggingface dataset:
Numerical Simulations, Mean Field Theory and Modulational Stability Analysis of Thermohaline Intrusions

Abstract : Thermohaline intrusions are produced by lateral shear advection across thermal and haline fronts, self-driven via double-diffusion, and cause significant lateral fluxes. The primary goal of this thesis is to understand the mechanisms responsible for their development and equilibration. Previous theories (mean-field models) were limited by their reliance on the vertical flux laws, which still remain a great source of uncertainty and require modelers to assume that intrusion development is uniquely determined by the background gradients. An alternative approach, based on the multiscale mechanics, views intrusions as modulational instability of the rapidly varying salt fingers. We present an exhaustive study on the effects of background parameters on the vertical and horizontal fluxes of temperature and salinity using two-dimensional numerical simulations. Specific experiments are designed to identify the most promising theoretical techniques for predicting intrusion evolution. Based on numerical results, the assessments of the two theoretical models are made and the mean field theory is found to be superior. Growth rates are calculated as a function of inclination of intrusions, which is used to determine the dominant modes by focusing on the fastest-growing instability. Equilibrium diffusivities are calculated to develop an explicit parameterization for the effects of thermohaline intrusions.
A method for estimating both the solubility parameters and molar volumes of liquids

The solubility parameters and molar volumes of substances can be used, in conjunction with suitable theory, to provide estimates of the thermodynamic properties of solutions; the solubility characteristics of polymer-solvent systems and the estimation of the equilibrium uptake of liquids by polymers are examples of the type of practical problems that are amenable to treatment. For low molecular weight liquids, the solubility parameter, δ, is conveniently calculated using the expression δ = (ΔEv/V)½, where ΔEv is the energy of vaporization at a given temperature and V is the corresponding molar volume which is calculated from the known values of molecular weight and density. For high molecular weight polymers, the volatility is much too low for ΔEv to be obtained directly and hence recourse must be made to indirect methods for estimating δ for these materials. One such widely used method is based on Small's additive group “molar-attraction constants” which when summed allow the estimation of δ from a knowledge of the structural formula of the material; however, the density must still be determined experimentally. The proposed method of estimating δ, also based on group additive constants is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of the structural formula of the compound.
Microbially-mediated gross N transfer rates in field soils in relation to physico-chemical transfer processes

Abstract Measurements of gross N transfer in soils have as yet not distinguished between biological or physico-chemical processes. Here, we present a new approach that allows microbially-mediated gross N transfer rates to be estimated in undisturbed soils without adding 15N. It is based on the assumption that in undisturbed soil, the soil microbial growth rate is equal to its death rate. To assess the contribution of biological versus physico-chemical N transfer processes, we combined the new approach with the 15N-pool dilution technique. The relationship between both processes varied with soil C and fine particle contents. Nearly equal rates were observed within the carbon-poor soil (0.35% Corg, low fine particle content), whereas up to 2.5 times higher physico-chemical than biological N transfer rates were measured within the carbon-enriched soil (0.86% Corg, higher fine particle content). Furthermore, microbially-mediated gross N transfer rates increased three-fold after N fertilization compared to the unfertilized control.
Synthesis and double‐hierarchical structure of MoS2/C nanospheres

The results of MoS2/carbon nanocomposite hydrothermal synthesis is presented. The synthesized material was studied by XRD, TEM, EDS, SAXS, and porosimetry. The multilayer nanospheres with the average size 40–70 nm were obtained. The investigations confirm the formation of particles with double‐hierarchical structure where 2H‐MoS2 layers alternate with carbon layers. Atomic ratio of MoS2:C is about 1:1 (at.%) and does not depend on the heat treatment.
An ab initio molecular orbital study comparing the bonding of the NH3 and the H2O in the monoammines and the monohydrates of main group and transition metal ions

It is common knowledge that some metal ions prefer to bond to nitrogen atoms, others prefer oxygen and others select sulfur, although the mechanistic origin of this behaviour is not well understood. To provide quantitative data that can illuminate this characteristic difference, we have been performing ab initio molecular orbital calculations on complexes of a wide variety of main group and transition metal ions with simple ligands. In this paper we concentrate on metal ion complexes of NH3 and compare them with the corresponding complexes with H2O (Trachtman et al., 1998, Inorg. Chem., 37, 4221). The results reported here show that for each metal ion the bonding to ammonia in monoammines is intrinsically stronger than that to water in monohydrates, but that the enthalpy of formation of the amine complexes has a greater sensitivity to the nature of the metal ion. For both mono- and divalent transition metal cations the ligand-field stabilization energy (LFSE) in the monoammine complexes is larger than that in the monohydrates, although the larger enthalpies of formation, ΔH 0 298, for the monoammines are due only in part to the larger LFSE values. The formation of both monoammines and monohydrates is accompanied by a transfer of charge from the ligand hydrogen atoms to the metal ion so that there is relatively little change in the net charge on the oxygen or nitrogen atoms. Hence the increased acidity of the ligand in the metal ion complex is not the result of net electron depletion of the atom that is directly bonded to the metal ion, but rather reflects weakening of the bond of that ligand atom to its proton (O-H or N-H). This characteristic is used by many enzymes to promote catalytic activity.
Oxidation of Cyclohexene to trans-1,2-Cyclohexanediol Promoted by p-Toluenesulfonic Acid without Organic Solvents

This experiment describes a method for cyclohexene oxidation to trans-1,2-cyclohexanediol using p-toluenesulfonic acid (p-TsOH) as promoter and hydrogen peroxide as oxidant in a biphasic system. This method allows conversions up to 97.9% (monitored by 1H NMR). trans-1,2-Cyclohexanediol was not easily separated from the aqueous solution owing to formation of an azeotropic mixture with water. Destruction of the azeotropic mixture was observed in the presence of sodium p-toluenesulfonate salt (p-TsONa). Therefore, water could be removed by simple distillation after p-TsOH neutralization. Purification of trans-1,2-cyclohexanediol was accomplished by sublimation. The overall reaction, separation, and purification experiment did not require any organic solvent.
Catalytic degradation of oxygenates in Fischer–Tropsch aqueous phase effluents to fuel gas via hydrodeoxygenation over Ru/AC catalyst

BACKGROUND: Aqueous phase Fischer–Tropsch (FT) effluents co-produced with hydrocarbons in the FT process contain various water-soluble oxygenates, e.g. carboxylic acids, alcohols. Purification of the FT aqueous phase is important from the viewpoint of effective resource utilization and environmental stewardship. In this work, an aqueous-phase hydrodeoxygenation process was investigated for the degradation of FT aqueous phases. RESULTS: The Ru/AC catalyst was determined to be the most active catalyst. The key parameters, i.e. temperature, pressure, weight hourly space velocity and Ru loading, were comprehensively optimized. Under optimal conditions, ca 98% of the oxygenates were converted to C1∼C6 alkanes. The degraded water had no odour, a neutral pH, and as low as 1000 mg L−1 chemical oxygen demand. The Ru/AC catalyst exhibited long-term stability (1300 h) and no ruthenium leaching. A reaction pathway is proposed for this process in which the carboxylic acids are hydrogenated to alcohols via the formation of aldehydes. Alcohols and aldehydes are then converted to methane and alkanes of one carbon atom less than the substrate through CC bond cleavage. CONCLUSIONS: This process is effective for treating FT aqueous phase effluent, and holds great promise for industrial applications due to its high efficiency, simplicity and stability. Copyright © 2011 Society of Chemical Industry
Numerical Approach to the Safety Evaluation of Sodium—Water Reaction

A numerical simulation method of multi-dimensional and multi-phase reacting flow (SERAPHIM code) has been developed to evaluate the sodium-water reaction (SWR) phenomena in a steam generator of liquid metal fast reactor (LMFR). A compressible multi-fluid and one-pressure model is adopted and pressure and velocity fields are updated simultaneously by the HSMAC method. Two types of reaction models are considered; one is a surface reaction and the other is a gas-phase reaction. The surface reaction model assumes that water vapor reacts with the liquid sodium at the gas-liquid interface. If chemical reaction heating is large enough, liquid sodium is vaporized resulting in a gas-phase reaction. In the surface reaction, the reaction rate is assumed to be infinitely large. Several overall reaction equations are taken into account in the gas-phase reaction and the reaction rates are described in the form of the Arrhenius law. In the present study, adequacy of the analytical procedures for compressible multi-phase flow is validated by a benchmark calculation of the Edwards pipe blowdown problem. As a numerical example, two- and three-dimension analyses of the single-tube geometry and the two-dimension analyses of the 43-tubes geometry are carried out. It is concluded that the numerical quantification of the SWR accident by the SERAPHIM code is practicable and further use of the SERAPHIM code is useful to resolve safety issues immanent in the SWR.
An investigation of the effect of silane water‐crosslinking on the properties of poly(L‐lactide)

A silane-grafting water-crosslinking approach was developed to crosslink poly(L-lactide) (PLLA) by grafting vinylalkoxysilane onto PLLA using dicumyl peroxide, followed by silane hydrolysis to form siloxane linkages between PLLA chains. The degree of silane grafting onto PLLA was qualitatively characterized using Fourier transform infrared spectroscopy and quantitatively determined using inductively coupled plasma mass spectrometry. Crosslinked PLLA films were obtained by curing of silane-grafted PLLA in hot water. Gel fractions were evaluated in order to calculate the crosslinking reaction kinetics and crosslinking density. Various techniques were used to investigate the effect of silane water-crosslinking on the thermomechanical properties, hydrolysis resistance and biodegradation of PLLA. In addition to an improvement in thermal stability and mechanical properties, hydrolysis resistance was significantly enhanced as a result of silane water-crosslinking of PLLA. Moreover, the biodegradation of silane water-crosslinked PLLA was retarded compared with neat PLLA. Copyright © 2010 Society of Chemical Industry
Synthesis and Surface Active Properties of Dimeric Gemini Sulfonate Surfactants

Abstract Dimeric Gemini sulfonate surfactants 1,2-di-(2-oxoypropyl sulfonate-3-alkylether- propoxy) ethane were prepared by the reaction of ethylene glycol diglycidyl ether with long-chain alcohols, followed by sulfonation with 1,3-propane sultone. Ethylene glycol ether was synthesized by the reaction of epichlorohydrin with ethylene glycol. The chemical structures of the prepared compounds were confirmed by FTIR, 1H NMR and elementary analysis. With the increasing length of the carbon chain, the values of their CMC initially decreased. The longer alkyl chain is, the higher melting point is. The Krafft point of Gemini sulfonate surfactants was below 0°C and they had good water solubility. These compounds were superior in surface active properties to general sulfonate surfactants SDS. The efficiency of adsorption at the water/air interface (pC20) of these surfactants was very high. Their foaming properties and wetting ability toward a felt chip, and lime-soap dispersing ability were investigated.
Extraction and Purification of Anthocyanins from the Fruit Residues of Vaccinium uliginosum Linn

An aqueous two-phase system was developed to extract anthocyanins present in the fruit residue during juice production from the fruit of Vaccinium uliginosum Linn. A maximum partition coefficient of 10.67 and a recovery of 96.09% for anthocyanins could be obtained using an extraction system consisted of 30% (w/w) ethanol and 19% ammonium sulfate. Compared with the traditional extraction using acidified ethanol, the novel aqueous two-phase extraction could not only yield a much higher concentration of anthocyanins, save more ethanol, energy, and time, but also decrease impurities in extract, e.g. proteins and sugars by 58% and 66%, respectively. AB-8 macroporous resin was applied to the purification of anthocyanins. A novel and simple separation technique for anthocyanins was developed by integrating aqueous two-phase extraction and macroporous resin column chromatography. This new technology might be a suitable for other bioactive natural products on industrial scale.
A new generalization of the Casimir–Polder potential to higher electric multipole polarizabilities

An elementary method for calculating retarded interaction energies for a pair of molecules with electric multipole polarizabilities of arbitrary order is presented. In the multipolar framework of quantum electrodynamics, the interaction energy is viewed as arising from two‐photon exchange and calculated using fourth order perturbation theory. It is shown how the energy may be expressed in terms of derivatives of the Casimir–Polder formula written in a special form as an integral over imaginary frequency. Explicit formulas are presented for (a) an electric dipole polarizable molecule interacting with an electric quadrupole polarizable molecule, (b) an electric dipole polarizable molecule interacting with an electric octupole polarizable molecule, and (c) an electric quadrupole polarizable molecule interacting with another electric quadrupole polarizable molecule. The results are expressed in terms of reducible and irreducible components of multipole moments. For case (b) it is shown that in addition to the.
Influence of Mg Vapor Pressure on the $MgB_2$/Carbon Fiber Fabricated by Physical Vapor Deposition method

Abstract -- We have fabricated the superconducting MgB 2 /carbon fiber by physical vapor deposition method. Mg (Magnesium) and B (Boron) were simultaneously deposited on the carbon fiber using the RF-sputtering and thermal evaporation, respectively. To ensure the relatively high vapor pressure of Mg at the growth region and the subsequent phase stability of MgB 2 at the deposition temperature, inverted funnel-like guide made of Mg-foil was employed while one side of the guide were open for the sputtered B flux. Mg vapor pressure should be controlled precisely to secure the complete reaction. The MgB 2 /carbon fiber showed a uniformly deposited thin layer with dense and well-formed grains. The MgB 2 /carbon fibers in this study showed c T~37.5K, J c ~ 2×10 4 A/cm 2 in the 20K, 0T. will be in the gas phase and be easily evacuated by the 1. INTRODUCTION The discovery of superconductivity in magnesium diboride (MgB 2 ) certainly revived the interest in the field of superconductivity, especially in non -oxide material system, and initiated a search for superconductivity in the related boron compounds [1- 3]. Its high critical temperature gave a hope for obtaining even higher
VARIATIONS IN WATER‐SOLUBLE SACCHARIDES AND PHENOLS IN LONGAN FRUIT PERICARP AFTER DRYING

Variations in the contents of water-soluble polysaccharides (WSP), water-soluble total saccharides (WSTS), gallic acid and total phenols in longan pericarp tissues of three major cultivars (“Shixia,”“Chuliang” and “Fuyan”) planted in Guangzhou, Gaozhou and Haikou, respectively, were evaluated. Microwave radiation, solar radiation and lyophilization were employed to dry the longan pericarps. A great variation in the contents of WSTS, WSP, total phenols and gallic acid existed in pericarp tissues of longan fruit among the three cultivars, locations and drying methods. The highest content (248.7-mg glucose equivalents [GE]/g dry weight [DW]) of WSTS was obtained in “Shixia” fruit from Haikou, while the lowest content (58.9-mg GE/g DW) was detected in “Fuyan” fruit from Guangzhou using lyophilization. WSP content was in a decreasing order except for cv. “Shixia” from Haikou, using the three various drying methods: microwave radiation > solar radiation > lyophilization. The longan pericarp tissues contained a large amount of phenolic compounds. “Shixia” fruit from Haikou had the highest content (49.4-mg gallic acid equivalents/g DW) of total phenols. The contents of total phenols followed a decreasing order for the three drying methods: lyophilization > microwave radiation > solar radiation. No gallic acid was detected in either fresh or lyophilized pericarp tissues, but it was found in the dried pericarp tissues with a higher content in fruit pericarp tissues dried by microwave radiation than by solar radiation. PRACTICAL APPLICATIONS There is increasing interest of utilizing saccharides and phenols from plant sources for their uses in medicine and cosmetics. Microwave radiation, solar radiation and lyophilization were employed to dry longan fruit pericarp tissues of three major cultivars in relation to their various production locations, while contents of water-soluble total saccharides (WSTS), water-soluble polysaccharides (WSP), total phenols and gallic acid in the pericarp were evaluated after these dryings. Significant variations in the contents of WSP, WSTS, gallic acid and total phenols of longan pericarp tissues among the three major cultivars and various locations and drying methods were found. This study can help utilize better the longan fruit pericarp in practice.
Monolayer graphene growth on sputtered thin film platinum

It is demonstrated that sputtered thin film platinum (Pt) can be used as a catalytic metal for graphene growth on metal. During the crystallization annealing, the sputtered Pt is crystallized mostly into Pt (111) orientation, maintaining excellent surface roughness with no sign of agglomeration. The relatively lower carbon solubility in Pt and the good surface roughness of the thin film Pt enable us to form a uniform monolayer graphene on Pt over the entire region of the thin film Pt/SiO2/Si substrate by carbon dissolution and segregation method processed in a methane ambient. The monolayer graphene grown on Pt has been successfully transferred to SiO2/Si substrate by simple wet etching of Pt. The results of Raman spectroscopic and scanning tunneling microscopic measurements of the synthesized graphene layer are presented.
A Segmentation Algorithm for the Automatic Recognition of Fuji Apples at Harvest

An algorithm for the automatic recognition of Fuji apples on the tree was developed for a robotic harvesting system. The machine vision system was composed of a colour charge coupled device camera to capture apple images, and a personal computer to process images for recognising and locating the fruit. The fruit image was enhanced using the red colour difference because results showed that the fruit had the highest red colour difference among the objects in the image. The intensity histogram of the enhanced image had a bimodal distribution for the fruit portion and the background portion. The maximum grey level variance of the red colour difference between the fruit and the background determined the optimal threshold. The optimal threshold had the minimum probability between the peaks of the two distributions. Results of the segmentation using the optimal threshold showed a success rate of over 88%. However, the error rate was over 18% for images with the back lighting condition.
Interplay of external and internal field effects on radiative recombination efficiency in InGaN quantum well diodes

Electroluminescence (EL) and photoluminescence (PL) properties have been investigated of the high-brightness green InGaN single quantum well (SQW) diode over a wide temperature range (T = 15–300 K) and as a function of injection current level. When the necessary forward bias conditions to get a certain current level are different, it is found that the anomalous temperature-dependent EL efficiency varies quite differently. That is, when the current is low and thus the forward driving voltage is small, the EL quenching observed below 100 K for high injection current levels is less significant or even absent due to the efficient carrier capture. This finding is consistent with decrease of the PL efficiency with increasing the bias over +2.5 V. These results indicate that the EL efficiency is significantly influenced by the interplay of internal and external field effects on the carrier capture and escape processes in addition to the localization phenomena caused by In fluctuations in the SQW layer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
A High Energy Density Asymmetric Supercapacitor from Nano‐architectured Ni(OH)2/Carbon Nanotube Electrodes

The demand for advanced energy storage devices such as supercapacitors and lithium‐ion batteries has been increasing to meet the application requirements of hybrid vehicles and renewable energy systems. A major limitation of state‐of‐art supercapacitors lies in their relatively low energy density compared with lithium batteries although they have superior power density and cycle life. Here, we report an additive‐free, nano‐architectured nickel hydroxide/carbon nanotube (Ni(OH)2/CNT) electrode for high energy density supercapacitors prepared by a facile two‐step fabrication method. This Ni(OH)2/CNT electrode consists of a thick layer of conformable Ni(OH)2 nano‐flakes on CNT bundles directly grown on Ni foams (NFs) with a very high areal mass loading of 4.85 mg cm−2 for Ni(OH)2. Our Ni(OH)2/CNT/NF electrode demonstrates the highest specific capacitance of 3300 F g−1 and highest areal capacitance of 16 F cm−2, to the best of our knowledge. An asymmetric supercapacitor using the Ni(OH)2/CNT/NF electrode as the anode assembled with an activated carbon (AC) cathode can achieve a high cell voltage of 1.8 V and an energy density up to 50.6 Wh/kg, over 10 times higher than that of traditional electrochemical double‐layer capacitors (EDLCs).