Miracle-dz/UniFAR-FTUs huggingface dataset:
Magnetic and Transport Properties of the System La1-xSrxCoO3-δ (0 < x ≤ 0.50)

Magnetic and transport measurements on the system La{sub 1-x}Sr{sub x} CoO{sub 3-{delta}}(0 < x {le} 0.50, {delta} = 0 for 0 {le} x < 0.30, and {delta} (x) {le} 0.06 for 0.30 {le} x {le} 0.50) have led to a phase diagram for this system. Upon Sr doping, the material segregates into hole-rich, metallic ferromagnetic regions and a hole-poor matrix similar to LaCoO{sub 3}. The Co ions of the ferromagnetic phase are in intermediate-spin configurations; the hole-poor matrix experiences a thermally induced low-spin to high-spin transition. For low Sr doping (x < 0.20), the hole-rich regions are isolated from one another and show superparamagnetic behavior below T{sub c}{approx}240 K; longrange magnetic order via frustrated intercluster interactions occurs below a superparamagnetic freezing temperature T{sub g} that increases with x. At x = 0.20, the coupling between the intermediate-spin, metallic ferromagnetic clusters within an interpenetrating matrix reaches a magnetic percolation threshold that orders the clusters ferromagnetically below T{sub c}{approx} 250 K. However, the electrical conduction in the ferromagnetic regions is modulated by the matrix, which has a spin state that varies with temperature. This causes a reentrant semiconductive behavior in the samples with 0.20 {le} x {le} 0.25. Metallic ferromagnetic behavior ismore » found for 0.30 {le} x {le} 0.50 even though the presence of an interpenetrating hole-poor matrix persists to x = 0.50. A ferromagnetic fraction less than unity leads to peculiar magnetic properties that have been attributed in the literature to a magnetic {open_quotes}cluster glass. {close_quotes}« less
Ascertaining the 1D Hydrogen-Bonded Network in Organic Ionic Solids

Crystal engineering concepts are exploited to generate a 1D hydrogen-bonded network in a series of organic salts (9−18) derived from dicyclohexylamine and various dicarboxylic acids (1−7) having linear as well as twisted/angular functional topology. It is clearly demonstrated that the cyclic 0D hydrogen-bonded network involving corresponding cations and anions in a secondary ammonium monocarboxylate salt (synthon B or C) can indeed be transformed into a 1D network in 1:2 (acid/amine) dicarboxylate systems (9−12). The effects of the twisted/angular functional topology of the anion moiety on the resultant supramolecular architectures in the corresponding 1:2 (acid/amine) salts (13−15) are examined. The 1:1 salts (16−18) of the dicarboxylic acids having twisted/angular functional topology also display a 1D network.
In situ loading of Ag nanocontacts onto silica nanospheres: a SERS platform for ultrasensitive detection

Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed SiO2@Ag nanospheres as an effective SERS detection platform through in situ loading Ag nanocontacts onto the SiO2 nanospheres, the well-designed and uniform nanocomposites provide highly enhanced effects for the tremendous SERS signal amplification. The huge enhanced effect might originate from the hot spots generated from the nanocontacts among the silver nanoparticles loaded onto the silica nanosphere, and also possibly from the nanogaps among the neighboring silver nanoparticles between the two silica nanospheres. The SERS enhancement factor of the SiO2@Ag nanospheres substrate is as high as 1016. Moreover, the as-fabricated SERS substrate can be employed to enhance the Raman signals of some chemicals that are harmful to environment including thiram, melamine and ethyl-parathion. The detection limits with the SERS platform are several orders of magnitude lower than the maximal residue limit (MRL) in fruit prescribed by U.S. Environmental Protection Agency (EPA). Therefore the surface lifting spectroscopic technique based on the SiO2@Ag nanosphere SERS platform offers great practical potential for the on-site assessment and identification of harmful chemicals with ultralow concentrations in agricultural products and environments.
Charge Density Quantification of Polyelectrolyte Polysaccharides by Conductometric Titration: An Analytical Chemistry Experiment

An easy analytical method for determination of the charge density of polyelectrolytes, including polysaccharides and other biopolymers, is presented. The basic principles of conductometric titration, which is used in the pulp and paper industry as well as in colloid and interface science, were adapted to quantify the charge densities of a negatively charged polysaccharide (pectin) and a positively charged biopolymer (chitosan), two biomacromolecules commonly used in food and biomaterials applications. This novel conductometric titration method can be easily applied in most analytical chemistry teaching laboratories, due to its ease-of-use, safety, and educational benefits. This analytical technique can also be used in a wide-range of laboratory activities and has extensive research applications in areas of chemistry involving charged biopolymers, such as food science, materials science, and physical chemistry.
Calculations of Electron Inelastic Mean Free Paths (IMFPs) IV. Evaluation of Calculated IMFPs and of the Predictive IMFP Formula TPP-2 for Electron Energies between 50 and 2000 eV

We have made additional evaluations of the electron inelastic mean free paths ([MFPs) and of the predictive IMFP formula TPP-2 presented in papers I1 and I11 of this series. Comparisons have been made with other formulae for the IMFPs and electron attenuation lengths (ALs). We find substantial differences between our IMFP results for 27 elements and 15 inorganic compounds and the AL formulae of Seah and Dench; these differences include different dependences on electron energy and on material parameters. We present IMFP calculations for A1,0, and GaAs from TPP-2 in which each parameter of the formula is varied in some physically reasonable range about the true value for each compound; these results show the sensitivity of the computed IMFPs to the choices of parameter values. Finally, we give a summary of sources of uncertainty in the IMFP algorithm, in the experimental optical data from which IMFPs are calculated, and of the TPP-2 formula. We conclude that TPP-2 is robust and useful for predicting IMFPs for electron energies and material parameter values in ranges for which the formula was developed and tested.
Partitioning of small alcohols into dimyristoyl phosphatidylcholine (DMPC) membranes: volumetric properties

Volume changes associated with the partitioning of eight different alcohols and acetone into unilamellar vesicles of dimyristoyl phosphatidylcholine in the fluid state was investigated by newly designed, automated titration densitometric equipment. The change in free volume of the partitioning process, expressed by changes in the specific excess volume of the solutions, was positive for all solutes. The magnitude of the total volume change per mole alcohol partitioned, ΔVm, was calculated by combining the volumetric data with previously published partitioning coefficients. For aliphatic 1-alcohols, ΔVm increased gradually from 3 cm3/mol for ethanol to ∼29 cm3/mol for 1-hexanol. Values of ΔVm for the cyclic alcohols c-hexanol and benzyl alcohol were ∼3 times smaller than for aliphatic compounds of a similar molecular weight. The composition dependence of the volumetric excess functions could be determined with sufficient accuracy to allow estimation of the partial specific excess volume of all three compon.
Structures and vibrational spectra of CH3OCH2CH2OH: the hydrogen-bonded conformers

Ab initio calculations at the MP2/6-31G* and MP2/6-31G*//6-31G* levels have been carried out for the monomer of 2-methoxyethanol (CH3OCH2CH2OH). The MP2/6-31G* results indicate that the two more stable conformers (tGg′ and gGg′) display intramolecular hydrogen bonds directed from the hydroxy H atom to one of the lone pairs of the ether O atom, and that the tGg′ conformer is 6.3 kJ mol–1 more stable than the gGg′ conformer. As the MP2/6-31G* and MP2/6-31G*//6-31G* calculations do not yield results differing by more than a few tenths of a kJ mol–1, it is concluded that the structure-sensitive and the dynamic correlation corrections are far from being additive. While the optimization of geometry for the correlated wavefunction generally leads to increase of bond lengths and reduction of bond angles, on the whole the geometrical parameters undergo similar changes in different conformers. Ab initio harmonic 6-31G* derived force fields were used to perform normal mode analyses for the more stable conformers. The calculated ν(CH) frequencies are found to correlate linearly with some of the ab initio calculated CH bond lengths. An interpretation of the FTIR and Raman spectra for the liquid phase consonant with the structural and vibrational ab initio results is presented. Two spectral features observed both in Raman and in FTIR spectra and associated with ν(OH) in monomeric species are ascribed to conformers, in accord with the theoretical and experimental results. On the whole, both the structural and the vibrational results presented point to a distinction between the hydrogen-bonded G-type conformers (tGg′ and gGg′) and the higher energy T-type conformers (tTg and tTt).
NUTRIENT DEPRIVATION AFFECTS XYLEM SAP FLOW AND WATER CHANNEL FUNCTION IN TOMATO PLANTS

Heat-balance sap-flow gauge was used to measure xylem sap flow through the main stem of tomato (Lycopersicum esculentum Mill. cv. Young-Kwang) plants grown under nitrogen- or phosphorus-deficient nutrient solutions for nine days. Nitrogen deficient plants transported less sap than phosphorus deficient plants. Moreover, the effect of nitrogen deficiency on xylem sap flow was rapid, appearing within one day of treatment. Addition of mercury to nutrient solution induced immediate and drastic reduction in sap flow of both control and nutrient deprived plants. Subsequent use of dithiothreitol (DTT), however, did not recover sap flow in nutrient deprived plants. This suggests that the alteration in the characteristics of water channel was due to nutrient deficiencies.
Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate and n-propyl cyanide in Sagittarius B2(N)

Context. In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. Aims. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. Methods. We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range, plus partial surveys at 2 and 1.3 mm. We analyzed this spectral survey in the local thermodynamical equilibrium approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code. Results. We report the first detection in space of ethyl formate (C 2 H 5 OCHO) and n -propyl cyanide (C 3 H 7 CN) toward Sgr B2(N). The detection of n -propyl cyanide is based on refined spectroscopic parameters derived from combined analyses of available laboratory spectroscopic data. For each molecule, we identified spectral features at the predicted frequencies having intensities compatible with a unique rotation temperature. For an assumed source size of 3″, our modeling yields a column density of 5.4 $\times$ 10 16 cm -2 , a temperature of 100 K, and a linewidth of 7 km s -1 for ethyl formate. n -Propyl cyanide is detected with two velocity components having column densities of 1.5 $\times$ 10 16 cm -2 and 6.6 $\times$ 10 15 cm -2 , respectively, for a source size of 3″, a temperature of 150 K, and a linewidth of 7 km s -1 . The abundances of ethyl formate and n -propyl cyanide relative to H 2 are estimated to be 3.6 $\times$ 10 -9 and 1.0 $\times$ 10 -9 , respectively. We derived column density ratios of 0.8/15/1 for the related species t -HCOOH/CH 3 OCHO/C 2 H 5 OCHO and 108/80/1 for CH 3 CN/C 2 H 5 CN/C 3 H 7 CN. Our chemical modeling reproduces these ratios reasonably well. It suggests that the sequential, piecewise construction of ethyl and n -propyl cyanide from their constituent functional groups on the grain surfaces is their most likely formation route. Ethyl formate is primarily formed on the grains by adding CH 3 to functional-group radicals derived from methyl formate, although ethanol may also be a precursor. Conclusions. The detection in Sgr B2(N) of the next stage of complexity in two classes of complex molecule, esters and alkyl cyanides, suggests that greater complexity in other classes of molecule may be present in the interstellar medium.
Metabolizable Bi2Se3 Nanoplates: Biodistribution, Toxicity, and Uses for Cancer Radiation Therapy and Imaging

Bi, a high atomic number element, has a high photoelectric absorption coefficient, and Se has anticancer activity. Hence, their compound chalcogenide (Bi2Se3) deserves a thorough investigation for biomedical applications. This study reveals that Bi2Se3 nanoplates (54 nm wide) protected with poly(vinylpyrollidone) (PVP) could be presumed to have low toxicity even at a high dose of 20 mg/kg in mice. This conclusion is made through studies on the biodistribution and 90‐day long term in vivo clearance of the nanoplates. The liver and spleen are dominant organs for accumulation of the nanoplates, which is mainly due to RES absorption. 93% of the nanoplates are cleared after 90 days of treatment. Concentrations of Bi and Se in tumor tissue continuously increased until 72 h after intraperitoneal injection into mice. Such selective accumulation of Bi is utilized to enhance the contrast of X‐ray computerized tomography (CT) images. Bi element concentrated in a tumor leads to damage on the tumor cells when exposed to gamma radiation. Growth of the tumor is significantly delayed and stopped in 16 days after the tumor is treated by radiation with Bi2Se3 nanoplates. This work clearly shows that Bi2Se3 nanoplates may be used for cancer radiation therapy and CT imaging. The nanoplates deserve further study for biological and medical applications.
A facile approach for synthesis and in situ modification of onion‐like carbon with molybdenum carbide

Uniform small onion‐like carbon (OLC) modified with molybdenum carbide has been synthesized by a one‐step process, using detonation‐assisted chemical vapor deposition. The obtained material was characterized by transmission electron microscope, energy‐dispersive X‐ray spectroscopy, Raman spectroscopy, and X‐ray diffraction. The results show that the OLC have almost perfect onion structures containing about 7–10 closed shells and exhibit a narrow distribution of 4–6 nm when the C/Mo ratio is about 150. The hexagonal molybdenum carbide (Mo2C) is dispersed on the surface of OLC. The size of OLC can be controlled by adjusting the C/Mo ratios. The formation mechanism of the nanocomposites of OLC and Mo2C is briefly discussed.
Response of methane emission and dissolved organic carbons to warming and nitrogen fertilization in boreal peatlands

Although most sources of greenhouse gases (GHG) have been extensively studied, relatively little is understood about the interactive effect of warming and nitrogen addition on methane (CH₄) emissions from boreal peatland. Since methane is a considerably more potent GHG compared to carbon dioxide (CO₂), studies investigating what physical and biological factors control methane emissions in boreal peatlands are becoming increasingly important as an increase in temperature increases the rate of CH₄ emission as well as enhancing the decomposition of dissolved organic matter (DOM). In this experiment, I investigated the response of CH₄ emissions and dissolved organic carbon (DOC) concentrations and optical characteristics to warming and nitrogen fertilization in boreal peatlands as a result of global climate change at a peat bog complex in western Newfoundland, Canada. I found that climate warming increased CH₄ emission and DOC concentration at 40 cm peat depth. In contrast, nitrogen (N) addition did not increase CH₄ emission in a boreal peatland. However, the interactive effect of warming and nitrogen addition decreased the rate of CH₄ emission due to the reducing effect of N-addition which counteracted the positive effect of warming in increasing the rate of CH₄ emission from boreal peatlands. This unexpected trend suggests unforeseen factors are involved in the process of methanogenesis that were beyond the scope of this experiment. However, the interactive effect of warming and N addition synergistically increased the DOC and total nitrogen (TN) concentrations at the 40 cm depth due to root exudates favoring DOC mineralization in boreal peatlands. The results further indicate that specific ultraviolet absorbance (SUVA₂₅₄) increased peat aromaticity. Furthermore, fluorescence index (FI) indicated the peat was of microbially (1.53-1.65) processed dissolved organic matter (DOM) over vascular plant derived DOM in peatland. Humification index (HIX) values for the treatment effects ranged between 0.15-0.17, indicating the peat carbon was not highly degraded and composed of less condensed molecules, indicating a decrease in recalcitrant humified carbon production.
Small wastewater systems in Portugal: Current situation and trends for the future

Portugal is a small Mediterranean country. Where wastewater treatment is concerned, the Portuguese levels of service in 2000 and 2006 were, respectively, 55% and 80%. These levels of service will continue to increase until 2013. Because of economic, environmental, and energy concerns, the design, construction, and operation of wastewater treatment plants (WWTPs) are currently under careful review in Portugal. Innovative designs continue to be developed and alternative treatment processes, specifically those based on natural systems, such as constructed wetlands, are being used. This paper presents information about investment costs of 165 wastewater treatment plants (WWTPs) built in Portugal between 2002 and 2004. The WWTPs were grouped in four population ranges that were analysed in terms of investment per capita costs. For the lowest range, up to 2000 inhabitants, the average investment cost was about €800 per inhabitant and just €89 per inhabitant for WWTPs serving more than 30,000 inhabitants. The anal.
Bending and twisting dynamics of short linear DNAs. Analysis of the triplet anisotropy decay of a 209 base pair fragment by Brownian simulation

Brownian dynamics is used to simulate the decay anisotropy of short linear DNA fragments modeled as a string of beads. The model is sufficiently general to allow for static bends, anisotropic bending, and elastic constants for bending and twisting which can vary along the chain. In limiting cases, simulations are found to be in excellent agreement with analytic theory down to a correlation length of at least 500 A. This model is then used to analyze the 0–2.5 μs triplet depletion anisotropy decay of a 209 base pair sea urchin DNA fragment. It is concluded that the conventional worm‐like chain model, in which bending is isotropic and/or there are no static bends along the chain, is unable to account for the experimental results unless a correlation length of 1000 A is assumed. A worm‐like chain with anisotropic bending requires a similar but slightly larger correlation length.
Raman-elastic-backscatter lidar for observations of tropospheric aerosol

In this work, a combined Raman-elastic backscatter lidar is described. It is based on a Q-switched powerful frequencydoubled Nd:YAG laser (output pulse power: up to 1 J at 1064 nm; up to 100 mJ at 532 nm; pulse duration 15 ns FWHM; repetition rate 2 Hz). A Cassegrain telescope (35 cm diameter, 200 cm focal length) collects backscattered radiation from atmospheric particles and molecules. Lidar's spectral receiving module consists of three cannels. The first two channels separate and detect elastic-backscattered lidar signals at laser wavelengths 1064 nm and 532 nm, respectively. In the third lidar channel, a radiation at a wavelength of 607 nm is selected and detected, resulting from Raman backscattering of laser second harmonic (532 nm) by atmospheric nitrogen molecules. Experimental profiles of the aerosol backscattering coefficient demonstrating measurement abilities of the system are shown and discussed. Particularly, attention is paid to profiles containing signals from high-altitude cirrus clouds, low-altitude stratus clouds, hazy atmospheric areas and Saharan dust over the city of Sofia.
Stimuli-induced gel–sol transition of multi-sensitive supramolecular β-cyclodextrin grafted alginate/ferrocene modified pluronic hydrogel

This paper studies a kind of biocompatible hydrogel composed of alginate-g-β-cyclodextrin (Alg-β-CD) and ferrocene-terminated pluronic F127 (F127-Fc), which showed gel–sol phase transformations in response to temperature, oxidizing agents, and glucose because of the reversible association–dissociation of Fc-β-CD inclusions and F127 micelles.
Hydrogenated Amorphous Silicon Oxide Solar Cells Fabricated near the Phase Transition between Amorphous and Microcrystalline Structures

We investigated the properties of hydrogenated amorphous silicon oxide (a-Si1-xOx:H) deposited near the phase transition between amorphous and microcrystalline structures. a-Si1-xOx:H films were prepared by plasma-enhanced chemical vapor deposition using a gas mixture of silane, hydrogen, and carbon dioxide. The film structure was changed from amorphous to microcrystalline phase by increasing hydrogen dilution. Optical and electrical characterizations revealed that wide-gap a-Si1-xOx:H films were deposited under phase transition conditions. We also fabricated a-Si1-xOx:H single-junction p–i–n solar cells by varying the hydrogen dilution for the i-layer. The solar cells showed a maximum open circuit voltage of 1.04 V (Jsc=7.92 mA/cm2, FF=0.64, Eff=5.2%) when the i-layer was deposited under phase transition conditions.
Adsorption of lead(II) from aqueous solution by activated carbon prepared from Eichhornia

Activated carbon prepared from Eichhornia was used for the adsorptive removal of Pb(II) from aqueous solution. As the raw material for the preparation of the activated carbon is an aquatic weed, the production of this carbon is expected to be economically feasible. Parameters such as agitation time, metal ion concentration, adsorbent dose and pH were studied. Adsorption equilibrium was reached in 100 min for a solution containing 15 mgdm−3 and 125 min for solutions containing 20 and 25 mgdm−3 Pb(II), respectively. Adsorption parameters were determined using both Langmuir and Freundlich isotherm models. The adsorption capacity was 16.61 mgg−1 at pH 3.0 for particle sizes of 125–180 µm. Pb(II) removal increased as the pH increased from 2 to 4 and remained constant up to pH 10.0. Desorption studies were also carried out with dilute hydrochloric acid to recover both carbon and Pb(II). Quantitative desorption of Pb(II) from carbon indicates that adsorption of metal ion is by ion exchange. © 2002 Society of Chemical Industry