Miracle-dz/UniFAR-FTUs huggingface dataset:
Development of a Low-Cost Four-Color LED Photometer

Instrumentation is becoming more important in all aspects of chemistry, from research to control of industrial processes. Due to this increasing reliance on instrumentation, students should begin working with instruments early in their training. However, the cost of having a sufficient number of instruments for this purpose is prohibitive. In an effort to reduce the rising cost of laboratory equipment used in general chemistry labs and to introduce instrumentation at the undergraduate level, we developed and tested a low-cost four-color LED photometer. This photometer resembles a Spectronic 20 in that it detects absorbance at selected wavelengths of visible light. However, the photometer retains the advantages of a dual-beam system. The cost is reduced by the elimination of all optical components, which are often the most expensive portion of spectrophotometers. Also, removal of the optical components permits the light source, sample chambers, and detectors to all be mounted in the same holder. This makes the unit very compact and easy to use in a student laboratory.
In silico screening of 4764 computation-ready, experimental metal–organic frameworks for CO2 separation

We report a molecular simulation study to screen 4764 computation-ready, experimental metal–organic frameworks (CoRE-MOFs) for CO2 separation from flue gas (CO2/N2) and natural gas (CO2/CH4). Quantitative relationships are established, for the first time, between the metal type and adsorbent evaluation criteria (adsorption selectivity and capacity, working capacity and regenerability). It is found that alkalis exist in 75% of alkali-MOFs as nonframework ions or open metal sites, and 75% of alkaline-MOFs contain alkalines as open metal sites; thus alkali- and alkaline-MOFs exhibit high adsorption selectivity and large capacity. Combining selectivity, working capacity and regenerability, however, alkali- and alkaline-MOFs possess the lowest performance for CO2 separation. Among ∼1000 lanthanide-based CoRE-MOFs, 50% contain lanthanides as open metal sites and have the highest performance. The best 30 CoRE-MOFs are identified for CO2/N2 and CO2/CH4 separation, and they mostly contain lanthanides. Furthermore, we predict the breakthrough curves in two identified CoRE-MOFs and demonstrate their superior separation performance. This modeling study highlights the central importance of adsorbent evaluation by holistic criteria, and suggests that lanthanides could be interesting metals in the design of new MOFs for CO2 separation.
Microphase separation of star-diblock copolymer melts studied by dissipative particle dynamics simulation

The microphase-separation behaviors of two types of star-diblock copolymers (A)4(B)4 and (AB)4 are investigated through the dissipative particle dynamics (DPD). The simulated phase diagrams show similar ordered mesostructures as those of corresponding linear and cyclic ones, such as lamellas (LAM), perforated lamellas (PL), hexagonal (HEX) cylinders and body-centered-cubic (BCC) spheres, besides, a series of gyroid (GR) morphologies predicted by theoretical research have been identified. In the regions between the totally ordered and disordered phases, we have found some melted morphologies that can be thought as locally ordered, such as micelles (M), liquid rods (LR) and random network (RN), which have not been identified in relevant theoretical predictions. The simulated threshold for a totally ordered mesostructure to appear is higher than theoretical predictions, which can be ascribed mainly to the increasing fluctuation with finite chain length, and the star architecture can facilitate microphase separation, which is in agreement with the theoretical predictions. In addition, it is easier for the (A) n (B) n copolymers than for corresponding (AB) n ones to trigger microphase separation under the same conditions. The relations between the root-mean-square radius of gyration (RMSGR) and the composition f A in the two types of star copolymers are almost contrary, which can be attributed to the differences in their structural characteristics.
The Cosmic Evolution Early Release Science (CEERS) Survey

We propose the Cosmic Evolution Early Release Science (CEERS) Survey (NOI #135), which covers 100 sq. arcmin with JWST imaging and spectroscopy, and is designed to achieve the DD-ERS goals. CEERS will inform the selection of a wide variety of spectroscopic targets for Cycle 2 with a practical choice of imaging area, depth, and wavelength coverage, targeting a field that is supported by a rich set of HST/CANDELS multi-wavelength data. CEERS will demonstrate, test, and validate efficient extragalactic surveys with coordinated, overlapping parallel observations with the JWST instrument suite, including NIRCam and MIRI imaging, NIRSpec R~100 and R~1000 spectroscopy, and NIRCam slitless grism (R~1500) spectroscopy. These tests enable Cycle 2 observations, including validating JWST parallel observing modes, dither and exposure-time strategies, and spectroscopic observing modes including slit-loss corrections. CEERS enables immediate community science into both extragalactic JWST science drivers “First Light and Reionization” and “The Assembly of Galaxies”, including: 1) The discovery of 20-80 galaxies at z~9-13, constraining their abundance and physical nature; 2) Deep spectra of >400 galaxies at z>3, including 40 known candidates at 6<z<9, enabling redshifts and constraints on physical conditions of star-formation and black hole growth via line diagnostics; 3) Quantifying the first bulge and disk structures at z>3; and 4) Characterizing galaxy mid-IR emission to study dust-obscured star-formation and supermassive black hole growth at z~1-3. The CEERS collaboration is diverse on many axes with demonstrated expertise in rapid delivery of high-level science products. Scientific Category: Galaxies and the IGM Scientific
Fresh tomato aroma volatiles: a quantitative study

Description d'une methode de piegeage sur Tenax suivie d'une separation par chromatographie gazeuse en colonne capillaire. L'identification est confirmee par spectrometrie de masse. Les resultats sont utilises pour evaluer les effets de la maturation et du stockage frigorifique sur les modifications de la flaveur des tomates
Differentiation of β-Sheet-Forming Structures: Ab Initio-Based Simulations of IR Absorption and Vibrational CD for Model Peptide and Protein β-Sheets

Ab initio quantum mechanical computations of force fields (FF) and atomic polar and axial tensors (APT and AAT) were carried out for triamide strands Ac-A-A-NH-CH3 clustered into single-, double-, and triple-strand β-sheet-like conformations. Models with φ, ψ, and ω angles constrained to values appropriate for planar antiparallel and parallel as well as coiled antiparallel (two-stranded) and twisted antiparallel and parallel sheets were computed. The FF, APT, and AAT values were transferred to corresponding larger oligopeptide β-sheet structures of up to five strands of eight residues each, and their respective IR and vibrational circular dichroism (VCD) spectra were simulated. The antiparallel planar models in a multiple-stranded assembly give a unique IR amide I spectrum with a high-intensity, low-frequency component, but they have very weak negative amide I VCD, both reflecting experimental patterns seen in aggregated structures. Parallel and twisted β-sheet structures do not develop a highly split ami.
A critical evaluation of the factors influencing the dissolution of Gafsa phosphate rock

SUMMARY A carbonate-substituted phosphate rock (Gafsa, GPR) was allowed to dissolve in the presence of one or more of the following: an acid pH buffer (a source of protons), hydrous ferric oxide gel (Fe gel, a sink for P), and a cation exchange membrane (CEM, a sink for calcium). This allowed a quantitative evaluation of the individual and combined influences of three of the most important soil-related factors (pH, P sink, and Ca sink) which control phosphate rock (PR) dissolution in soils. At 44 d, pH alone (pH 6.1 compared to 4.5) had little effect on the extent of dissolution (1.5 and 6.0% dissolution of P, respectively), probably because of the Ca common-ion effect resulting from the preferential dissolution of the more-soluble CaCO, accessory phase. The inclusion of a P sink at pH 6.2 resulted in only a 3.2% dissolution of P after 44 d, whereas at pH 4.5 it increased dissolution from 6.0% to 9.8%. This suggests that pH and P sorption have an interactive effect in influencing GPR dissolution. Inclusion of a Ca sink had the largest influence on GPR dissolution. This was due to the ability of the Ca sink to remove accessory CaCO2. At pH 6.2 the dissolution of P was 10 times larger in the presence of a Ca sink than it was in the presence of a P sink. Despite the smaller ratio of Ca sink size to GPR-Ca content relative to that of the P sink size to GPR-P content, the Ca sink was more effective in promoting GPR dissolution. The presence of the Ca sink resulted in twice as much dissolution of P at pH 4.5 than at pH 6.5. At pH 4.5, and in the presence of both the Ca sink and the P sink, 95% dissolution of GPR occurred over the 44-d experimental period.
Study on operation of a microbial fuel cell using mesophilic anaerobic sludge

A two-chamber microbial fuel cell (anaerobic anode chamber and air-sparged cathode chamber) was designed and built in our laboratory where carbon fibres were used as electrodes and Nafion 0125 protonselective membrane was placed between the two cells. Anaerobic sludge from a local biogas plant was applied in the anode chamber and various substrates were used to study the operation of the system and to measure the electric power generated.
The influence of sub‐optimal irrigation and drought on crop yield, N uptake and risk of N leaching from sugarbeet

Abstract. Variously timed sub‐optimal irrigation strategies were applied to sugarbeet grown on a light soil (loamy sand or sandy loam) over four seasons (1991 to 1994) to investigate the effect on crop growth and nitrate leaching risk. Data from the two dry seasons, (1991 and 1994) are reported here. In the driest year (1991) soil mineral N levels after autumn harvest were negatively related to crop water use (P < 0.05). In this season, there was little drainage from the soil profile, and full irrigation reduced residual soil N by 31 kg N/ha (0‐90 cm) compared with the unirrigated treatment (79 kg N/ha). The potential for N leaching during the ensuing winter was consequently more than halved. In 1991 and 1994 there was a strong positive linear relationship between dry matter yield, N uptake and water use, but a negative relationship between plant N concentration and water use. These relationships were a function of the severity and not the timing of drought. The additional N uptake associated with increased irrigation and crop water use was biased towards a large concentration in the aboveground crop (tops), which are normally returned to the soil. The C:N ratio of sugarbeet tops was affected by crop water supply with droughted crops having lower values. This would also influence N release and subsequent leaching risk. However, the effects of drought on N leaching risk were relatively small when compared with other root crops such as potatoes.
Interactions between soil drying due to plant water use and decreases in aggregate stability caused by maize roots

Summary In a sandy loam soil the stability of freshly sampled aggregates, determined by turbidimetry, showed a net decrease following the growth of maize that was partly offset when the plants dried the soil over a period of 9 days. The cause of this restabilization on drying may be the adsorption onto soil surfaces of polysaccharide materials produced in the rhizosphere.
Solid-phase Microextraction of Insect Epicuticular Hydrocarbons for Gas Chromatographic/Mass Spectrometric Analysis

A recently developed solvent-free sampling method, solid-phase microextraction, has been employed for sampling the cuticular hydrocarbons from three species of social wasps for GM/MS analysis. Comparison between the gas chromatograms of cuticular hydrocarbons obtained by microextraction and those of hexane-extracted samples from the same specimens shows that solid-phase microextraction is very suitable for sampling insect cuticle hydrocarbons, including those of high molecular weight. Because of its simplicity, this method is very suitable for routine work. © 1997 John Wiley & Sons, Ltd.
Quantitative interpretation of pH distributions in aquatic sediments: A reaction-transport modeling approach

Despite its status of master variable, there have been relatively few attempts to quantitatively predict the distributions of pH in biogeochemical reactive transport systems. Here, we propose a theoretical approach for calculating the vertical pore water profiles of pH and the rates of proton production and consumption in aquatic sediments. In this approach, the stoichiometric coefficients of species that participate in acid-base equilibrium reactions are treated as unknown variables in the biogeochemical reaction network. The mixed kinetic-equilibrium reaction system results in a set of coupled differential and algebraic equations and is solved using a new numerical solver. The diagnostic capabilities of the model are illustrated for depositional conditions representative of those encountered on the continental shelf. The early diagenetic reaction network includes the major microbial degradation pathways of organic matter and associated secondary redox reactions, mineral precipitation and dissolution processes, and homogeneous acid-base reactions. The resulting pH profile in this baseline simulation exhibits a sharp decrease below the sediment-water interface, followed by an increase with depth and again a decrease. The features of the pH profile are explained in terms of the production and consumption of protons by the various biogeochemical processes. Secondary oxygenation reactions are the principal proton producers within the oxic zone, while reduction of iron and manganese oxyhydroxides are primarily responsible for the reversal in the pH gradient in the suboxic zone. Proton production in the zone of sulfate reduction outweighs alkalinity production, maintaining the undersaturation of the pore waters with respect to calcite. Integrated over the entire depth of early diagenesis, dissolution of CaCO 3 is the main sink for protons. Variations in the reaction rate order and rate constant for CaCO 3 dissolution do not fundamentally alter the shape of the pH profile. An entirely different shape is obtained, however, when the pore waters are assumed to remain in thermodynamic equilibrium with calcite at all depths. Pore water (bio)irrigation decreases the amplitude of pH changes in the sediment and may modify the shape of the pH profile.
Dispersing Carbon Nanotubes in Aqueous Solutions by a Starlike Block Copolymer

The ability of dispersing carbon nanotubes (CNTs) in aqueous solutions by a starlike amphiphilic block copolymer with PPO−PEO segments (AP432) was investigated in detail. For comparison, two commercially available linear amphiphilic block copolymers, Pluronics L64 and F127, were also selected. It was found that AP432 and F127 can get good CNT dispersions, while L64 was proved to be unable to disperse CNTs. AP432 with five branches could disperse CNTs efficiently at much lower concentrations compared with the linear F127, although it has a smaller molecular weight and shorter terminal EO groups. This indicated clearly that, once branched, copolymers would get a much better ability to disperse CNTs. Increasing concentration of AP432 or F127 would disperse more CNTs, but at high copolymer concentrations the aggregation of dispersed CNTs was observed, which may be related to the free micelles formed by AP432 or F127 around CNTs. Other influencing factors such as the mass ratio of CNTs to copolymers and sonica.
Unique Combination of Mechanical Strength, Thermal Stability, and High Ion Conduction in PMMA−Silica Nanocomposites Containing High Loadings of Ionic Liquid

We report the simple synthesis of tractable and high ion conducting PMMA-silica nanocomposites achieved by sol−gel processing. Mechanical strength was obtained by incorporating silica nanofillers covalently bonded to the polymer chains, whereas flexibility, thermal stability, and high ionic conduction were provided by the ionic liquid.
The structure of schwertmannite, a nanocrystalline iron oxyhydroxysulfate

Abstract Schwertmannite is a poorly crystalline mineral that forms ochre rusts and precipitates in acid mine environments. Despite its ubiquity and its role as scavenger of important contaminants such as arsenic or selenium, its structure has not been yet determined. Here, a structure for schwertmannite is presented based on pair distribution function (PDF) data, X-ray diffraction (XRD) analyses, and density functional theory (DFT) calculations. We propose a structure formed by a deformed frame of iron octahedra similar to that of akaganeite. Simulations of X-ray diffraction patterns unveil the presence of long-range order associated with the position of the sulfate molecules, providing a useful way to discern two types of sulfate complexes in the structure. The simulations suggest that two sulfate molecules per unit cell are present in the structure forming one outer sphere and one inner sphere complex inside the channels formed by iron octahedra. Knowledge of the positions of the sulfates in the structure will help to better understand exchange processes with oxyanions of trace contaminants, such as arsenate, chromate, or selenate, that strongly influence their biogeochemical cycling in mining ecosystems.
Synthesis and characterization of inorganic silicon oxycarbide glass thin films by reactive rf-magnetron sputtering

Silicon oxycarbide glasses have been of interest because of the potential range of properties they might exhibit through a change in carbon-to-oxygen ratio. They are metastable materials and, as such, their structures and properties are very dependent upon the synthesis method. Silicon oxycarbide bonding has been seen in materials made by melting, oxidation, polycarbosilane or sol/gel pyrolysis, and chemical vapor deposition. In this work, the radio-frequency reactive sputtering of silicon carbide targets was explored for synthesis of amorphous silicon oxycarbide thin films. SiO(2−2x)Cx films, with a continuous range of compositions where 0⩽x⩽1, were deposited by controlling the amount of oxygen present in the plasma with a SiC target. This resulted in a density range from 1.9to2. 8g∕cm3 and a range of refractive indexes from 1.35 to 2.85. Analysis of the film compositions, structures, and properties were performed using x-ray photoelectron spectroscopy, infrared spectroscopy, nuclear magnetic resonance, p.
Differential effect of organic cultivation on the levels of phenolics, peroxidase and capsidiol in sweet peppers

BACKGROUND: Coincident with the changes in agricultural practices from conventional to organic, changes in the nutrient composition of fresh fruits and vegetables have been identified. The levels of peroxidase, total phenolics content, and capsidiol activity in organic as compared with conventional sweet pepper fruit were examined in this study. In order to avoid interferences of environmental factors on the studied parameters, the sweet peppers were grown (organically and conventionally) in a greenhouse under the same soil and climate conditions. RESULTS: Peroxidase was partially purified using the Triton X-114 method and both organic and conventional peppers had the same isoenzymatic form. However, peroxidase activity in organic sweet peppers was higher than in conventional ones, in both maturity stages studied. The level of total phenolics compunds was also higher in organic than in conventional sweet peppers. With respect to the capsidiol activity, expressed as inhibition of fungus growth, it was not affected by the cultivation method at the green mature stage. However, at the red mature stage, organic sweet peppers showed higher capsidiol activity than those grown under the conventional system. CONCLUSION: Sweet peppers grown under organic culture have a maturity-related response, with high levels of phenolic compounds, and peroxidase and capsidiol activity that contribute to disease resistance in organic farming. Copyright © 2007 Society of Chemical Industry
Phosphodiester Stretching Bands in the Infrared Spectra of Human Tissues and Cultured Cells

Methodology has been developed recently in our Ottawa laboratory to obtain infrared spectra of intact biological tissues and whole cells with extremely high signal-to-noise ratio. This development has allowed us to evaluate the structural properties of biomolecules in tissue sections and exfoliated cells of human neoplasms by monitoring their infrared spectra (Refs. 2 and 3 and research submitted for publication). During this work we found that several changes in the infrared spectra of malignant tissues and cells are common to all cancers which we studied, including those of the colon, stomach, esophagus, skin, liver, cervix, and vagina (Refs. 2 and 3 and research submitted for publication). It is important to know the structural origin of these spectral changes, since they may reflect a step of a shared pathway in carcinogenesis. The most striking changes in the spectra that are common to various malignant tissues and cells are observed in the symmetric (νsPO2−) and asymmetric (νasPO2−) stretching bands of phosphodiester groups. These results suggest that in all cancerous tissues and cells studied to date most PO2− groups become hydrogen bonded and that the intermolecular packing among neighboring PO2− groups becomes closer. (Refs. 2 and 3 and research submitted for publication). Indirect evidence, discussed later, pointed to nucleic acids as the molecules mainly responsible for the observed changes in the νsPO2− and νasPO2− bands. Since any information concerning structural changes in nucleic acids associated with malignancy is potentially significant for our understanding of cancer, we sought to confirm the molecular origin of the phosphodiester stretching modes in the infrared spectra of tissues and whole cells. We therefore investigated the infrared spectra of human malignant colon tissues, cultured human colon adenocarcinoma cells, and the nuclei, DNA, RNA, and lipids isolated from the cultured adenocarcinoma cells. Moreover, the correlation of the intensities of the νas,PO2− and ,νsPO2− bands in the infrared spectra of human thymus and muscle tissues with their relative concentrations of nucleic acids in the cells has been studied.
Isentropic advection and convective lifting of water vapor in the UT - LS as observed over Brazil (22° S) in February 2004 by in situ high-resolution measurements of H 2 O, CH 4 , O 3 and temperature

The micro-SDLA balloonborne diode laser spectrometer was flown twice from Bauru (22° S, Brazil) in February 2004 during HIBISCUS to yield in situ H 2 O measurements in the Upper Troposphere (UT) and Lower Stratosphere (LS) and in particular in the Tropical Tropopause Layer (TTL). The overall TTL was found warmer (with a subsaturated cold point near –79°C) and the LS moister compared to former measurements obtained in tropical oceanic conditions. The use of specific balloons with a slow descent, combined with the high-resolution of the laser sensor, allowed us to observe in situ in the UT, the TTL and the LS several thin layers correlated on H 2 O, CH 4 , O 3 , temperature and PV. A component of these layers is associated with the isentropic transport into the UT- LS of extratropical stratospheric air masses. Moreover, the examination of temperature and tracer (CH 4 , O 3 ) profiles gives insights on the potential contribution of convective transport of H 2 O in the TTL.