Miracle-dz/UniFAR-FTUs huggingface dataset:
Single‐Crystal Germanium Growth on Amorphous Silicon

Growing single‐crystal semiconductors directly on an amorphous substrate without epitaxy or wafer bonding has long been a significant fundamental challenge in materials science. Such technology is especially important for semiconductor devices that require cost‐effective, high‐throughput fabrication, including thin‐film solar cells and transistors on glass substrates as well as large‐scale active photonic circuits on Si using back‐end‐of‐line CMOS technology. This work demonstrates a CMOS‐compatible method of fabricating high‐quality germanium single crystals on amorphous silicon at low temperatures of <450 °C. Grain orientation selection by geometric confinement of polycrystalline germanium films selectively grown on amorphous silicon by chemical vapor deposition is presented, where the confinement selects the fast‐growing grains for extended growth and eventually leads to single crystalline material. Germanium crystals grown using this method exhibit (110) texture and twin‐mediated growth. A model of confined growth is developed to predict the optimal confining channel dimensions for consistent, single‐crystal growth. Germanium films grown from one‐dimensional confinement exhibit a 200% grain size increase at 1 μm film thickness compared to unconfined films, while 2D confinement growth achieved single crystal Ge. The area of single crystalline Ge on amorphous layers is only limited by the growth time. Significant enhancement in room temperature photoluminescence and reduction in residual carrier density have been achieved using confined growth, demonstrating excellent optoelectronic properties. This growth method is readily extensible to any materials system capable of selective non‐epitaxial deposition, thus allowing for the fabrication of devices from high‐quality single crystal material when only an amorphous substrate is available.
Silicate Anion Structural Change in Calcium Silicate Hydrate Gel on Dissolution of Hydrated Cement

High pH conditions of aqueous solutions in a radioactive waste repository can be brought about by dissolution of cementitious materials. In order to clarify the mechanisms involved in maintaining this high pH for long time, we investigated the dissolution phenomena of OPC hydrate. In the present research, leaching tests on powdered cement hydrates were conducted by changing the ratio of mass of leaching water to mass of OPC hydrate (liquid/solid ratio) from 10∽2, 000 (wt/wt). Ordinary Portland Cement hydrate was contacted with deionized water and placed in a sealed bottle. After a predetermined period, the solid was separated from the solution. From the results of XRD analysis on the solid phase and the Ca concentration in the aqueous phase, it was confirmed that Ca(OH)2 was preferentially dissolved when the liquid/solid ratio was 10 or 100 (wt/wt), and that C—S—H gel as well as Ca(OH)2 were dissolved when the liquid/solid ratio was 500 (wt/wt) or larger. 29Si-NMR results showed that the silicate anion chain of the C-S-H gel became longer when the liquid/solid ratio was 500 (wt/wt) or greater. This indicates that leaching of OPC hydrate results in a structural change of C—S—H gel.
POST-EXCAVATION CHANGES IN IRON ANTIQUITIES

AbstractThe chemical changes occurring in iron antiquities after excavation have been found to be identical to those occurring during the oxidation of ferrous ions in the presence of chloride. It has been shown that these reactions can occur at relative humidities as low as 20%. This knowledge of the changes that may occur, together with that of the structure of excavated objects, enables suggestions to be made as to the likely effectiveness of various storage environments and washing methods for archaeological iron.
First-principles investigations on the magnetic property in tripotassium doped picene

First-principles calculations are performed to investigate the magnetic characteristics in the tripotassium doped picene, especially for the effects induced by the volume variations. When changing volume, both crystal lattice constants and atomic positions are optimized. For the system with the experimental crystal volume, the doped picene shows a weak antiferromagnetic instability. When the volume expands from this experimental crystal volume, the antiferromagnetic spin ordering becomes clear. The electronic structures show that the magnetism comes from the spin unbalance on the π orbitals of the C atoms. On the contrary, both ferromagnetic and antiferromagnetic spin orderings are strongly suppressed as the volume is reduced. Our results indicate that the magnetism is sensitive to the variation of volume or pressure in the tripotassium doped picene. No metal-insulator transition is observed for several considered volumes.
Molecular Dynamics Simulations of Nucleic Acids with a Generalized Born Solvation Model

A generalized Born (GB) model has been applied to molecular dynamics simulations of the A- and B-forms of a duplex DNA d(CCAACGTTGG)2 and the corresponding duplex RNA r(CCAACGUUGG)2, resulting in good agreement with simulations using explicit water solvent in terms of both structure and energetics. In particular, the A → B energy differences derived from GB trajectories for both DNA and RNA closely match those obtained earlier using explicit water simulations and finite-difference Poisson−Boltzmann calculations. A GB simulation starting from A-form DNA converges to B-DNA within 20 ps, more than 20 times faster than the transition from A- to B-DNA in explicit solvent simulations. For B-form d(CCAACGTTGG)2, fluctuations about the mean are highly correlated between GB and explicit water simulations, being slightly larger in the former, and the essential subspaces found from principal component analysis overlap to a high degree. Hence, for many purposes this parametrization offers an alternative to more expen.
Management systems for conservation fallow on the southern Canadian prairies

Fallow continues to be a common agronomic practice on the southern Canadian prairies, but it has been associated with increased soil erosion and salinity and declining soil fertility. Field experiments were conducted at Lethbridge, Alberta, from 1987 to 1992 to determine the effects of various fallow treatments on weed control, conservation of surface crop residues, accumulation of soil water, and succeeding spring and winter wheat yields. Conventional cultivation during the fallow year with 168-cm sweeps controlled most spring-germinating weeds but did not adequately control overwintered flix-weed or downy brome. Repeated applications of glyphosate and 2,4-D effectively controlled most weeds. Paraquat did not control wild buckwheat or dandelion. Glyphosate alone often did not control wild buckwheat or Russian thistle. Treatments involving a combination of herbicides and tillage gave the best control of all weed species. Although not as effective in conserving surface crop residues as sole use of herbicid.
Preferential transport of phosphorus in drained grassland soils

Phosphorus is the limiting factor for primary production in most freshwater ecosystems. In many areas, diffuse P losses from intensively cultivated land cause severe eutrophication of surface waters. We investigated the P export from two drainage systems under intensively used grassland in a catchment of the Swiss Plateau. Flow rate and nutrient concentrations were measured with a high temporal resolution during discharge events. During most flow peaks, P concentrations strongly increased with increasing flow rates. Concentrations of soluble-reactive P (SRP) reached up to 155 μmol L -1 . Phosphorus was mainly transported as soluble-reactive and particulate P. Organic P compounds, as well as P associated with colloids between 0.05 and 0.45 μm in effective diameter, were of minor importance. Estimated P loads from the drainage systems were 227 g SRP ha -1 within a period of 2.5 mo at site I and 1290 g ha -1 during 6 mo at site II. Estimation uncertainty was large (±21 and ±36% for the two sites, respectively) due to the weak correlation between discharge and concentration for all data from a given site. Water-extractable P in the soil was concentrated in the uppermost layer of the profiles or, for short periods after spreading of manure, deposited on the vegetation. The discharge-concentration relationship indicated that P was transported through preferential flow paths extending from close to the surface to the drains. Sprinkling experiments with a blue dye confirmed this conclusion. At one site, we observed preferential flow in a downhill direction within the saturated zone.
INTEGRATION OF ACTIVE THIN FILMS WITH SILICON COMPATIBLE MATERIALS AND PROCESS SCIENCE PROTOCOLS FOR MEMS SCALE VIBRATION DAMPING APPLICATIONS

ABSTRACT Utilizing a BaSrTiO3/NiTi hybrid composite thin film design on a silicon substrate we have successfully fabricated, characterized, and optimized a high performance vibration control pedestal for passive damping of die level MEMS components. The thin film fabrication and integration protocols were accomplished via semiconductor industry standard processing methods and procedures. The ferroelectric tetragonal phase of BaSrTiO3 was deposited by metalorganic solution deposition (MOSD) technique followed by annealing in flowing oxygen. Thin film NiTi was sputter deposited utilizing a TiNi target in an ultrahigh vacuum chamber, followed by in situ vacuum annealing. Comparison of a variety of designs and integration processing protocols demonstrated that the sequential deposition of the BaSrTiO3 and NiTi thin films, followed by their respective optimized crystallization anneals at 750 and 500°C, achieved successful materials compatible monolithic integration of the composite bi-layer stack with the Si support wafer. The impact of this materials integration technology, based on foundry friendly film deposition techniques and integration procedures, serves to promote wide-scale implementation of vibration control passive damping for a variety of device/die level structures.
Simple Systematization of Structural Stability for ANB8-N Compounds

The structural stability of ANB8-N compounds such as GaAs, GaN, and NaCl is systematically investigated using our simple criterion on the basis of the ionicity, bond charge, and ionic charge of the ANB8-N compounds. The criterion implies that the wurtzite structure is more stable than the zinc blende structure when the ionicity is greater than 0.319 for N=4 (group IV), 0.455 for N=3 (III–V), 0.652 for N=2 (II–VI), and 0.882 for N=1 (I–VII compounds). Furthermore, the rocksalt structure is stabilized at ionicities greater than 0.479 for N=4 (group IV), 0.620 for N=3 (III–V), 0.786 for N=2 (II–VI), and 0.936 for N=1 (I–VII compounds). This simple criterion is successfully applied to predict the structural phase diagram of ANB8-N compounds as a function of ionicity and ionic charge.
PODZOLIZATION: SOIL PROCESSES CONTROL DISSOLVED ORGANIC CARBON CONCENTRATIONS IN STREAM WATER

We measured dissolved organic carbon (DOC) in soil solutions collected from the A and B horizons of a Spodosol in central New Hampshire. DOC averaged 33 mg/L in the A2 horizon and declined to 2 to 3 mg/L, similar to stream water concentrations, in the B horizon. DOC concentrations in A2 horizon lysimeters were inversely related to the volume of water collected per day; we observed maximum concentrations (approximately 55 mg/L) during September. In the B horizon lysimeters, DOC levels were relatively constant, as were levels in stream water. In laboratory experiments, DOC in A2 horizon soil solution was rapidly absorbed by B horizon soils. The equilibrium DOC concentrations predicted by adsorption isotherms agreed to within 1 to 2 mg/L with lysimeter results. Our results suggest that coprecipitation of iron and organic matter in the upper B horizon, a process central to podzolization, largely controls the concentration of dissolved organic carbon in stream water at Hubbard Brook.
ZINC EXCHANGEABILITY AS A FUNCTION OF PH IN CITRIC ACID-AMENDED SOILS

Organic C additions and changes in soil chemical properties caused by waste disposal, root exudation, and organic matter (OM) decomposition processes affect heavy metal solubility, mobility, and bioavailability. The solubility and exchangeability of zinc (Zn) were determined in two contrasting Maryland A horizon soils to evaluate the influence of an organic C amendment (citric acid) on Zn retention and cation exchange capacity as a function of pH, two properties that interact to control Zn speciation in soils. Water soluble Zn in the A horizons of Galestown loamy sand (Psammentic Hapludults) and Jackland silt loam (Typic Hapludalfs) soils, with and without citric acid addition, decreased with increasing pH from 4.0 to 7.0 and with increasing cation exchange capacity (CEC) from 4.7 to 96.7 mmolc/kg soil. At pH values < 5.0, the water soluble Zn fraction dominated and became exchangeable Zn as pH increased from 5.0 to 7.0 in the Galestown soil, whereas the exchangeable Zn fraction dominated from pH 4.0 to pH 6.0 and became nonexchangeable Zn as pH increased to 7.0 in the Jackland soil. Citric acid addition, compared with no citric acid addition, lowered (P < 0.05) the solubility of Zn and favored the exchangeability of Zn at pH < 5.0, and this effect of C addition on the solubility of Zn was more pronounced in the coarse-textured Galestown sandy soil than it was in the finer textured Jackland soil. The addition of citric acid at a Zn/citric acid molar ratio of 1:1 enhanced nonexchangeable Zn through chemisorption at pH > 6.0, whereas the effect of citric acid on levels of nonexchangeable form of Zn retention was not significant at pH < 6.0. The citric acid addition caused an abrupt transition from water soluble and exchangeable to nonexchangeable forms of retention and reduced the potential availability of Zn in the Jackland soil as soil pH approached 6.0. The results indicate that the pH influence on CEC was the dominant factor influencing the effect of citric acid on the redistribution of water soluble, exchangeable, and nonexchangeable Zn, especially in the finer textured soil. These results have implications for controlling soil pH to minimize Zn activity and bioavailability in soils used for organic waste disposal.
CRYSTALS OF INTERFACES : THE CUBIC PHASES OF AMPHIPHILE/WATER SYSTEMS

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. CRYSTALS OF INTERFACES : THE CUBIC PHASES OF AMPHIPHILE/WATER SYSTEMS J. Charvolin
Speciation of eight arsenic compounds in human urine by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection using antimonate for internal chromatographic standardization

Four anionic and four cationic arsenic compounds in urine were separated by anion- and cation-exchange high-performance liquid chromatography and detected by inductively coupled plasma mass spectrometry (ICP-MS) at m/z 75. The species were the anions arsenite, arsenate, monomethylarsonate and dimethylarsinate and the cations arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium ion. Hexahydroxyantimonate(III) was co-chromatographed with the arsenic anions but detected at m/z 121 and used as an internal standard for their qualitative analysis. Arsenite was prone to oxidation to arsenate in urine but was stable after at least 4-fold dilution of the urine with water. Arsenite was unstable in both urine samples and standard mixtures when diluted with the basic (pH 10.3) mobile phase used for anion chromatography. This could not be prevented by adding ascorbic acid as antioxidant. The argon chloride interference at m/z 75 was eliminated by chromatographic separation of the chloride present in the sample from the arsenic analytes. The ClO+ ion detected at m/z 51 and 53 was used to monitor the retention time of chloride in the anion-exchange system. The chloride eluted about 100 s after the last analyte peak and the intensity of ArCl+ was negligible even after injection of a 1% NaCl solution (less than 200 ions s–1). The recovery of all arsenic species in urine was close to 100%. The chromatographic peaks were evaluated by their peak heights and calibration was carried out by the method of standard additions. The calibration graphs were linear for all species (r > 0.999). The limits of detection were 3–6 ng cm–3 for the cations and 7–10 ng cm–3 for the anions in urine.
Majority and minority electron and hole mobilities in heavily doped GaAs

The majority electron and minority hole mobilities have been calculated in GaAs for donor densities between 5×1016 and 1×1019 cm−3. Similarly, the majority hole and minority electron mobilities have been calculated for acceptor densities between 5×1016 and 1×1020 cm−3. All the important scattering mechanisms have been included. The ionized impurity and carrier–carrier scattering processes have been treated with a phase‐shift analysis. These calculations are the first to use a phase‐shift analysis for minority carriers scattering from majority carriers. The results are in good agreement with experiment, but predict that at high dopant densities minority mobilities should increase with increasing dopant density for a short range of densities. This effect occurs because of the reduction of plasmon scattering and the removal of carriers from carrier–carrier scattering because of the Pauli exclusion principle. Some recent experiments support this finding. These calculations do not treat the density‐of‐states m.
Sodium Storage Behavior in Natural Graphite using Ether‐based Electrolyte Systems

This work reports that natural graphite is capable of Na insertion and extraction with a remarkable reversibility using ether‐based electrolytes. Natural graphite (the most well‐known anode material for Li–ion batteries) has been barely studied as a suitable anode for Na rechargeable batteries due to the lack of Na intercalation capability. Herein, graphite is not only capable of Na intercalation but also exhibits outstanding performance as an anode for Na ion batteries. The graphite anode delivers a reversible capacity of ≈150 mAh g−1 with a cycle stability for 2500 cycles, and more than 75 mAh g−1 at 10 A g−1 despite its micrometer‐size (≈100 μm). An Na storage mechanism in graphite, where Na+‐solvent co‐intercalation occurs combined with partial pseudocapacitive behaviors, is revealed in detail. It is demonstrated that the electrolyte solvent species significantly affect the electrochemical properties, not only rate capability but also redox potential. The feasibility of graphite in a Na full cell is also confirmed in conjunction with the Na1.5VPO4. 8F0.7 cathode, delivering an energy of ≈120 Wh kg−1 while maintaining ≈70% of the initial capacity after 250 cycles. This exceptional behavior of natural graphite promises new avenues for the development of cost‐effective and reliable Na ion batteries.
Active metasurface for controlling reflection and absorption properties

A novel active metasurface is proposed in this paper. The proposed metasurface can be electronically switched between the reflection and the absorption modes by a tunable component, such as a PIN diode. When the PIN diode is in the on-state, the proposed metasurface exhibits near-perfect absorptivity at 10 GHz. On the other hand, when the PIN diode is in the off-state, the proposed metasurface exhibits near-perfect reflectivity over a wide bandwidth at 10 GHz. A unit cell is designed to include a DC bias network, which yields reliable performance.
Preparation of Rhodium Catalysts Supported on Carbon Nanotubes by a Surface Mediated Organometallic Reaction

The dimeric complex [Rh2Cl2(CO)4] was grafted to multi-walled carbon nanotubes (MWNTs) previously oxidised with nitric acid and then treated with sodium carbonate to produce carboxylate groups on their outer surface. The grafting mechanism involves bridge-splitting and substitution of -COO for Cl, as evidenced by the presence of NaCl in the samples. A further reduction/decomposition step under dihydrogen at 573 K afforded highly dispersed rhodium nanoparticles (≈1.5−2.5 nm). This novel rhodium-supported carbon material (Rh/MWNT-COONa) was tested as a catalyst for the hydrogenation of trans-cinnamaldehyde and the hydroformylation of hex-1-ene in the liquid phase: in both cases it was found to be very selective, toward C=C double-bond hydrogenation and the production of linear and branched aldehydes, respectively. A comparison was made between its catalytic activity and that of rhodium supported on pristine MWNTs and on nitric acid-oxidised MWNTs. We observed that these latter catalysts have larger particle sizes and lower activities, thus confirming the efficiency of our grafting procedure. Moreover, the better results obtained when using MWNT-COONa as support with respect to carboxylate-containing activated carbon also point to the important role played by the mesoporous nature of the carbon nanotube support, which can ameliorate transfer processes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The coil–globule transition: Radius of gyration of polystyrene in cyclohexane

The temperature dependence of the radius of gyration of polystyrene (MW=2.6×107) in cyclohexane in the good through poor solvent regimes was obtained by analysis of the angular dependence of the autocorrelation function of light scattered from the solution. The observed transition in polymer dimensions through the coil to globule states is in good agreement with the predictions of mean field theory.
Temperature Measurements in a Temperate Glacier

Temperatures have been measured at two sites in a temperate glacier (Blue Glacier, Washington, U.S.A.) to depths of 192 and 76 m. The accuracy, which varies between about 0.002 and 0.005 deg, is about an order of magnitude better than previously obtained. Except near the surface, temperatures vary linearly with depth but are in disagreement with the simplest model of a temperate glacier, being about 0.02 deg colder near the surface and 0.04 deg colder at 192 m depth.
Measurements of NO Emissions From a Stratified Charge Engine: Comparison of Theory and Experiment

Abstract Measurements of NO exhaust emissions have been made on a single-cylinder engine with and without stratification. The results were compared with predictions based on an existing computer model of Blumberg (1973). Combustion duration, a critical parameter of the model, was inferred from experimental pressure-time records for each condition studied. In premixed operation at low NO levels the post-flame Zeldovich kinetics, as used by Lavoie et al, (1970), could not account for the observed concentrations. The discrepancy was ascribed to flame-formed NO, and a correction to the chemical kinetics was made based on the measurements of Fenimore (1970). With this correction good qualitative agreement between theory and experiment was obtained for the premixed case. On the basis of these results the modified kinetics were also employed in the stratified charge calculations. For stratified operation, calculations were made with a number of assumed stratification functions and the results compared with exper.
An efficient synthesis of warfarin acetals on montmorillonite clay K-10 with microwaves

The microwave promoted reaction of warfarin with methanol, or ethanol, in the presence of montmorillonite clay K-10 as a catalyst, affords the corresponding acetals, 2-methoxy 2-methyl-4-phenyl-3,4-dihydro-2H-pyrano[3,2-c]chromen-5-one (2) and 2-ethoxy-2-methyl- 4-phenyl-3,4-dihydro-2H-pyrano[3,2-c]chromen-5-one (3) respectively, in good yields.