Miracle-dz/UniFAR-FTUs huggingface dataset:
The Effects of Chain Length and Thermal Denaturation on Helix-Forming Peptides: A Mode-Specific Analysis Using 2D FT-IR

The major goal of this project was to use FT-IR spectroscopy to monitor the effects of chain length and temperature on small, helix-forming peptides of the general form, Ac-W(EAAAR)nA-NH2, where n ) 1, 3, 5, and 7, in aqueous solutions. FT-IR spectra were collected in D2O as a function of temperature in the range of - 4t o 95 °C. The spectral range of interest, 1500-1725 cm -1 , contains the amide-Iband of the fully-exchanged H f D peptide bond. Even in these simple peptides, the amide-Iregion of the IR spectra is complex and congested, composed of features derived from the conformation of the peptide backbone and from the contributions of amino acid side chains. Unambiguous resolution of peak positions and intensities is thus extremely difficult, particularly when assessing subtle differences between two data sets. Two-dimensional correlation analysis (Noda, I. J. Am. Chem. Soc. 1989, 111, 8116. Noda, I. Applied Spectrosc. 1990, 44, 550) was used to guide and verify the results of the peak-fitting procedure and thereby facilitate physical interpretation of the temperature-dependent spectra. The results of the two-dimensional analysis and fitting procedure show that the spectral bands, particularly those of the amide-Iband, exhibit significant frequency shifts and bandwidth and intensity changes as a function of temperature and chain length. For the amide-Imodes arising from the helical and random conformations of the peptide bond, the normalization of peak intensities to units of molar absorptivity is discussed in terms of different models. Two different molar absorptivity calculations are presented, the first using the length-dependence of R-helical frequencies as predicted by perturbation theory, and the second assuming a more rigorous two-state transition. The results from each are discussed in terms of the effects of chain length on R-helix stabilization and in terms of a mechanism of helix unfolding.
Rational design of a solid acid catalyst for the conversion of methanol to light alkenes: synthesis, structure and performance of DAF-4

By careful choice of the appropriate organic template, new shape-selective solid acid catalysts—framework-substituted microporous aluminium phosphates (AIPO4) that are structurally analogous to the mineral levyne—are designed, synthesised and characterized; they convert methanol preferentially to ethane and propene.
Poly(styrene-co-acrylic acid) core and silver nanoparticle/silica shell composite microspheres as high performance surface-enhanced Raman spectroscopy (SERS) substrate and molecular barcode label

A new type of polymer core and silver nanoparticle/silica shell multifunctional composite microsphere is reported. The monodisperse polymer core of poly(styrene-co-acrylic acid), prepared by surfactant-free emulsion polymerization, serves as the supporting template to facilitate the synthesis and handling of the highly functionalized substrates to achieve consistent mechanical and surface chemical properties. The shell of silver nanoparticles, formed in situ by controlled interfacial reduction of AgNO3 with polyvinylpyrrolidone (PVP), serves as the optimal metal enhancer for surface enhanced Raman spectroscopy (SERS). The Ag nanoparticle shell is stabilized with a silica layer using a sol–gel process, which is also functionalizable with reactive epoxides for further bio-conjugation using epoxy ring-opening methods. Preliminary results indicated that the microspheres are easily prepared with exceptional chemical and physical uniformity. SERS experiments with 4-aminobenzenethiol (4-ABT) as the indicator showed that the resulting multifunctional microspheres allowed the production of highly consistent enhancement of the Raman signals down to nM concentrations of 4-ABT, making them highly desirable candidates as the enhancers for high performance SERS analysis and as SERS optical labels in biomedical imaging. The microspheres are robust and the high density of the SERS active Ag nanoparticles on the microspheres provided unique signal averaging for the method to be potentially quantitative which is an urgent goal for SERS substrate design and SERS analysis.
Reinforcement with cellulose nanocrystals of poly(vinyl alcohol) hydrogels prepared by cyclic freezing and thawing

Cellulose nanocrystals (CNCs) were incorporated into polyvinyl alcohol (PVA) hydrogels prepared by repeated freeze–thaw processing. The CNC-loaded hydrogels had improved structural stabilities and distinct microstructures, characterized by ordered domains of CNCs. The water sorption of the gels increased with CNC content due to the hydrophilic nature of the cellulose and the decrease in PVA crystallinity. A reinforcement effect was observed in the CNC-loaded samples upon the application of uniaxial, confined compression, with the elastic moduli of the PVA–CNC samples increased relative to pure PVA hydrogels. Hydraulic permeability values were derived from the stress transients: at strains of ∼15 to 20% and greater, the permeability of all samples approached a plateau value reflective of the hindered flow in soft gels which have been compressed, densified and dehydrated.
The Evaluation of Six Lactose-Based Materials as Direct Compression Tablet Excipients

AbstractSix lactose-based products have been evaluated as direct-compression tableting excipients in a simple formulation. Anhydrous Lactose, NF was the best material overall, with Fas:-Flo lactose and Ludipress also being very good. The compaction properties of these products changed to varying degrees when tablets were made on a rotary press instead of a single punch press, and when machine speed was increased on the rotary machine.Compendial specifications cannot adequately differentiate between products with differing compaction properties.
Fabrication of curved structures with electron-beam and surface structure characterization

In this article, we propose a fabrication technology for preparing curved structures using an electron-beam writing strategy. Oxygen plasma treatment increases the surface roughness of SU-8 polymer, while minimizing the outgassing problem and stabilizing the SU-8 film. Fourier transform infrared spectra of epoxy bond near 915 cm−1 decreased upon increasing the dosage of the electron beam or the treatment time of the oxygen plasma. Convex, concave, and spiral structures were formed successfully using a gradient dosing strategy. The interface between two shot sections was smoothed by the electron scattering effect. The curved profile was fabricated at various curvatures, and characterized using scanning electron microscopy and a profiler. In addition, a spiral structure was fabricated that possesses the advantageous feature of having a small chip area. We discuss a method of characterizing the spiral structure.
Structural evolution and visible photoluminescence of Zn–ZnO nanophosphor

The Zn–ZnO nanostructure thin films are prepared by an inexpensive vacuum arc‐discharge method combined with vacuum annealing. The structural analysis of the grazing‐incidence X‐ray diffraction pattern using the Rietveld method showed the formation of Zn–ZnO in a single phase. The coexistence of Zn and ZnO in the thin‐film sample was also confirmed using transmission electron microscopy technique. Studies of optical properties by photoluminescence (PL) spectroscopy exhibit a strong violet emission accompanied by weak blue and green emission. The origin of defect emission of Zn–ZnO nanostructure was analyzed. Thus, the existence of metallic Zn nanocrystals embedded in ZnO islands provides a considerable change in the PL mechanism. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, Structure and Second Harmonic Effect of Bis(mu2-3,5-dinitrobenzoato-O,O')zinc(II) and Tetraaquabis(3,5-dinitrobenzoato-O)cobalt(II) Tetrahydrate

The crystal structures of [Zn(dnb)2]n and [Co(dnb)2(H2O)4]·4H2O (dnb = 3,5-dinitrobenzoate) have been determined based on single-crystal X-ray diffraction data. [Zn(dnb)2]n crystallizes in the trigonal space group P 3 1 2 1 , a 11.042(4), b 11.042(4), c 11.498(5) A, Z 3, R1 0.0230, wR2 0.0554. The zinc complex features infinite chiral chains in the solid, in which each pair of adjacent tetrahedrally coordinated zinc atoms are bridged by two dnb ligands, exhibiting powder second harmonic generation efficiency 0.34 times that of urea. [Co(dnb)2(H2O)4]·4H2O crystallizes in the triclinic space group P1, a 7.169(6), b 11.672(7), c 14.951(7) A, a 102.940(10), b 98.36(10), g 92.390(10)˚, Z 2, R1 = 0.0417, wR2 0.0966. The cobalt complex exists as mononuclear molecules in the lattice, in which the cobalt atom is coordinated by two monodentate dnb ligands and four aqua ligands in an octahedral arrangement.
Relationship of Sperm Characteristics, in Reference with DNA Fragmentation, with Fertility of Some Sheep Breeds in Egypt.

ABSTRACTThe objective of this study was to adopt an accurate in vitro test (sperm DNA damage) to predictfertility through ram spermatozoa. Semen was collected once a week for 8 collection weeks from six rams ofRahmani and Romanov breeds, 3 rams from each breed. Semen was evaluated for ejaculate volume, spermconcentration, progressive motility, livability and abnormality of spermatozoa. DNA damage test wasapplied with Halosperm kit. Results showed significant (P<0.05) individual differences in percentages ofabnormality and DNA damage in both breeds as well as in percentages of progressive motility, livabilityand total sperm output in Romanove breed. Breed had a significant (P<0.05) effect only on ejaculate volumeand total sperm output, being higher in Rahmani compared to Romanove breed. Sperm abnormality, spermcell concentration and DNA damage showed an opposite trend with respect to breed effect. Rams showedthe best semen quality in both breed had the highest conception rate (CR). Mean of CR was higher (P<0.05)in Rahmani than Romanov breed (88.38 vs. 78.79%, respectively). Percentages of progressive motility andlivability of spermatozoa were negatively correlated (P<0.05) with DNA damage and positively with CRonly in Rahmani breed. In both breeds, DNA damage had (P<0.01) a positive and strong correlation withpercentage of abnormal sperm where it was r= 0.557 in Rahmani and r=0.840 in Romanov. In addition, CRhad a positive correlation with sperm cell concentration in Rahmani and Romanove rams. The correlationbetween CR and sperm DNA damage was strong and negative (P<0.01) in both breeds (r=-0.699 forRahmani and -0.795 for Romanov). In conclusion, the present study indicated the strong negativecorrelations between sperm DNA damage percentage of abnormal spermatozoa and conception ratesespecially for Romanov rams which showed lower CR. Thus, in vitro sperm DNA damage test can used forevaluating fertility, in accompany with standard semen analysis assays.
Molecular mechanisms of photoaging in human skin in vivo and their prevention by all-trans retinoic acid.

Abstract— Solar UV radiation damages human skin, affecting skin tone and resiliency and leading to premature aging (photoaging), the symptoms of which include leathery texture, wrinkles, mottled pigmentation, laxity and sallowness. We propose that photoaging results largely from UV induction of matrix metalloproteinases (MMP) that degrade skin collagen. We find that pretreatment of human skin with all-trans retinoic acid (tRA) inhibits UV induction of MMP, suggesting that tRA can protect against UV-induced collagen destruction and may therefore be able to lessen the effects of photoaging. The tRA prevents UV-induced accumulation of c-Jun protein, which is required for MMP gene expression. Activation of c-Jun transcriptional activity requires N-terminal phosphorylation. The majority of c-Jun in human skin in vivo is Nterminal phosphorylated. Topically applied tRA does not inhibit N-terminal phosphorylation by UV-induced c-Jun kinase activity in human skin. The tRA likely acts to reduce UV induction of c-Jun protein by stimulating its breakdown through the ubiquitin-proteasome pathway.
Toward a better understanding of the bioavailability, physiology, and toxicity of silver in fish: Implications for water quality criteria

In its ionic form, silver (Ag+) is highly toxic to fish (96‐h 50% lethal concentration [LC50]: low μg/L range). However, concentrations of Ag+ in aquatic environments are extremely low and other more common forms of silver show only low to moderate toxicities (e.g., 96‐h LC50: silver thiosulfate >100,000 μg Ag/L; silver chlorides >100 μg Ag/L). In bioassays with freshwater fish, acute toxicity appears to be derived exclusively from the Ag+ ion concentration of the water. Some other forms of silver are bioavailable but do not show obvious contribution to acute toxicity. Complexation of Ag+ by chloride, dissolved organic carbon, and sulfide are important in reducing silver toxicity. The protective action of hardness (i.e. calcium) is modest. When added as the readily dissociating silver nitrate salt, the toxicity of silver is considerably lower in seawater (96‐h LC50 range: 330–2,700 μg Ag/L) than in freshwater (96‐h LC50 range: 5–70 μg Ag/L). Acute silver toxicity to fish is caused by failure of the organism to maintain constant Na+ and Cl− concentrations in the blood plasma. In freshwater fish, Ag+ exerts its toxic effects on the Na+ and Cl− transport across the gills, whereas the intestine has been indicated as the site of toxicity in seawater fish. Although there are still many gaps in our understanding of silver effects on fish, it can be concluded that present regulatory standards for silver can be much improved by taking into account the important geochemical modifiers of silver toxicity.
Surface passivation of phosphorus‐diffused n+‐type emitters by plasma‐assisted atomic‐layer deposited Al2O3

In recent years Al2O3 has received tremendous interest in the photovoltaic community for the application as surface passivation layer for crystalline silicon. Especially p‐type c‐Si surfaces are very effectively passivated by Al2O3, including p‐type emitters, due to the high fixed negative charge in the Al2O3 film. In this Letter we show that Al2O3 prepared by plasma‐assisted atomic layer deposition (ALD) can actually provide a good level of surface passivation for highly doped n‐type emitters in the range of 10–100 Ω/sq with implied‐Voc values up to 680 mV. For n‐type emitters in the range of 100–200 Ω/sq the implied‐Voc drops to a value of 600 mV for a 200 Ω/sq emitter, indicating a decreased level of surface passivation. For even lighter doped n‐type surfaces the passivation quality increases again to implied‐Voc values well above 700 mV. Hence, the results presented here indicate that within a certain doping range, highly doped n‐ and p‐type surfaces can be passivated simultaneously by Al2O3. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A simplified parametric model to describe the magnitude and geometry of soil shrinkage

Assessing the magnitude and geometry of soil shrinkage is indispensable for sound use and management of swelling and shrinking soils for agriculture and engineering. We have explored a simplified parametric model for the soil shrinkage characteristic curve, which is a measure for the magnitude of soil shrinkage, and tested it against experimental data for a Vertisol and a Lixisol under sugar cane in the Havana province, Cuba. We then applied the model to determine soil consistency limits, including the shrinkage, plastic and structural limits, using the model's third and fourth derivative. We further demonstrated how the model can be used to assess the geometry of shrinkage in terms of the relative crack area and the relative surface subsidence. Excellent matches were obtained between the observations and the fitted model. The shrinkage and structural limits corresponded to distinct changes in the soil shrinkage characteristic curve and were as such considered to be correctly estimated. The accuracy of the estimated plastic limit could, however, not been verified, since data were lacking. Linear regressions with R2 > 0.88 were established relating the shrinkage and plastic limits to the soil's COLE index and the cation exchange capacity. The model could be easily applied to determine the crack area and the surface subsidence. We finally demonstrated how a geometry factor rs plays a crucial role in determining the shrinkage geometry, particularly for rs values ranging from 1 to 3.
Impact of photovoltaic orientation on its relative economic value in wholesale energy markets

Most calculations of optimum photovoltaic (PV) performance focus on maximizing annual energy production. However, given the seasonally and daily time varying electricity demand and resulting variation in price, the PV orientation resulting in maximum energy yield may not yield the maximum economic benefit. With the use of historical solar irradiance and wholesale market prices for several locations in the USA, we evaluate the benefits of a variety of orientations for fixed and tracking PV arrays. We find that orienting fixed arrays slightly to the west of due south generally increases their economic value in the simulated systems because the reduced generation on an annual basis is more than offset by increased generation in high‐value hours in late summer afternoons. However, this effect is small, typically providing an increase in value from 1% to 5%. The economic value of adjusting the orientation semi‐annually (May 1st and September 1st) and monthly shows a modest increase in value from 3% to 5%. Several other implications of this analysis are also discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Experimental Demonstration of Advanced Palladium Membrane Separators for Central High Purity Hydrogen Production

The overall objectives for this project were to: (1) confirm the high stability and resistance of a PdCu trimetallic alloy to carbon and carbide formation and, in addition, resistance to sulfur, halides, and ammonia; (2) develop a sulfur, halide, and ammonia resistant alloy membrane with a projected hydrogen permeance of 25 m{sup 3}m{sup -2}atm{sup -0.5}h{sup -1} at 400 C and capable of operating at pressures of 12.1 MPa ({approx}120 atm, 1750 psia); and (3) construct and experimentally validate the performance of 0.1 kg/day H{sup 2} PdCu trimetallic alloy membrane separators at feed pressures of 2 MPa (290 psia) in the presence of H{sub 2}S, NH{sub 3}, and HCl. This project successfully increased the technology readiness level of palladium-based metallic membranes for hydrogen separation from coal-biomass gasifier exhaust or similar hydrogen-containing gas streams. The reversible tolerance of palladium-copper (PdCu) alloys was demonstrated for H{sub 2}S concentrations varying from 20 ppmv up to 487 ppmv and NH{sub 3} concentrations up to 9 ppmv. In addition, atomistic modeling validated the resistance of PdCu alloys to carbon formation, irreversible sulfur corrosion, and chlorine attack. The experimental program highlighted two key issues which must be addressed as part of future experimental programs: (1) tube defectsmore » and (2) non-membrane materials of construction. Four out of five FCC PdCu separators developed leaks during the course of the experimental program because {approx}10% of the alloy tubes contained a single defect that resulted in a thin, weak point in the tube walls. These defects limited operation of the existing tubes to less than 220 psig. For commercial applications of a PdCu alloy hydrogen separator under high sulfur concentrations, it was determined that stainless steel 316 is not suitable for housing or supporting the device. Testing with sulfur concentrations of 487 {+-} 4 ppmv resulted in severe corrosion of the stainless steel components of the separators. The project identified an experimental methodology for quantifying the impact of gas contaminants on PdCu alloy membrane performance as well as an atomistic modeling approach to screen metal alloys for their resistance to irreversible sulfur corrosion. Initial mathematical descriptions of the effect of species such as CO and H{sub 2}S were developed, but require further experimental work to refine. At the end of the project, an improvement to the experimental approach for acquiring the necessary data for the permeability model was demonstrated in preliminary tests on an enhanced PdCu separator. All of the key DOE 2010 technical targets were met or exceeded except for the hydrogen flux. The highest flux observed for the project, 125 ft{sup 3}ft{sup -2}h{sup -1}, was obtained on a single tube separator with the aforementioned enhanced PdCu separator with a hydrogen feed pressure of 185 psig at 500 C. « less
Properties of phenol-formaldehyde resins prepared from phenol-liquefied lignin

In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H2SO4) or hydrochloric acid (HCl) as the catalyst. The phenol-liquefied lignins were used as raw materials to prepare resol-type phenol-formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol-liquefied lignin-based PF resins had shorter gel time at 135°C and had lower exothermic peak temperature during DSC heat-scanning than that of normal PF resin. The thermo-degradation of cured phenol-liquefied lignin-based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol-liquefied lignin-based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Characterization challenges for nanomaterials

Nanostructured materials are increasingly subject to nearly every type of chemical and physical analysis possible. Due to their small sizes, there is a significant focus on tools with high spatial resolution. It is also natural to characterize nanomaterials using tools designed to analyze surfaces, because of their high surface area. Regardless of the approach, nanostructured materials present a variety of obstacles to adequate, useful, and needed analysis. Case studies of measurements on ceria and iron metal‐core/oxide‐shell nanoparticles are used to introduce some of the issues that frequently need to be addressed during analysis of nanostructured materials. We use a combination of tools for routine analysis including X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x‐ray diffraction (XRD) and apply several other methods as needed to obtain essential information. The examples provide an introduction to other issues and complications associated with the analysis of nanostructured materials including particle stability, probe effects, environmental effects, specimen handling, surface coating, contamination, and time. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation on the mobility and stability in organic thin film transistors consisting of bilayer gate dielectrics

One of the important problems in organic thin film transistors (OTFTs) is the existence of traps on oxide gate dielectrics which degrades the device performance and stability. By modifying the dielectric oxide surface, we obtained devices with bilayer dielectrics that show high mobility and good operational stability compared with the devices based on bare silicon dioxide dielectric layer. The average carrier mobility increases from 0.19 (without surface modification) to 0.35, 0.51, and 0.97 cm2 V−1 s−1 after employing a thin layer of hexamethyldisilazane (HMDS), polymethylmethacrylate (PMMA), and polystyrene (PS), respectively. The PS‐modified device exhibits the superior mobility, operational, and air stability in comparison with other devices. We ascribe these results to fewer traps caused by the OH group or OH‐induced water at the interface of semiconductor and the dielectric layer. In our study, the morphology of the semiconductor layer seems to have limited influence on the mobility and operational stability.