Infrared Spectrum

Aims. This work aims at investigating the molecular gas in the surroundings of the ultra-compact HII region G045.47+0.05 looking for evidence of molecular outflows. Methods. We carried out observations towards a region of 2 × 2 centered at RA = 19 h 14 m 25.6 s , Dec = +11 • 09 27.6 (J2000) using the Atacama Submillimeter Telescope Experiment (ASTE; Chile) in the 12 CO J = 3-2, 13 CO J = 3-2, HCO + J = 4-3, and CS J = 7-6 lines with an angular resolution of 22 . We complement these observations with public infrared data. Results. We characterize the physical parameters of the molecular clump where G045.47+0.0 is embedded. The detection of the CS J = 7-6 line emission in the region reveals that the ultra-compact HII region G045.47+0.0 has not completely disrupted the dense gas where it was born. The HCO + abundance observed towards G045.47+0.0 suggests there is molecular outflow activity in the region. From the analysis of the 12 CO J = 3-2 transition we report bipolar molecular outflows with a total mass of about 300 M . We derive a dynamical time (flow's age) of about 10 5 yr for the outflow gas, in agreement with the presence of an ultra-compact HII region. We identify the source 2MASS 19142564+1109283 as the massive protostar candidate to drive the molecular outflows. Based on the analysis of its spectral energy distribution, we infer that it is an early B-type star of about 15 M . The results of this work support the scenario where the formation of massive stars, at least up to early B-type stars, is similar to that of low-mass stars.

Calcium phosphate powders for manufacturing bioceramics were synthesized via precipitation from stock solutions of (NH4)2HPO4 and Ca(NO3)2, or CaCl2 or Ca(CH3COO)2 with [Ca2+]/[PO 43−] = 1, without pH regulation. Properties of powdered samples, including density and microstructure of ceramics sintered at 900, 1000, 1100°C, were studied. The following pairs of precursors such as Ca(NO3)2/(NH4)2HPO4, CaCl2/(NH4)2HPO4, Ca(CH3COO)2/(NH4)2HPO4 gave both insoluble calcium phosphates and the corresponding by-products of synthesis — NH4NO3, NH4Cl, NH4CH3COO. These by-products were released from the calcium phosphate precipitates in the course of heating to the temperature of sintering. Owing to specific buffer properties of the solutions being formed during synthesis, the pH value varied in a wide range during the precipitation process leading to different final values of pH and, thus, to different target phase(s) after annealing at 900–1100°C. After sintering, the samples based on the powd...

Two hybrid materials based on decavanadates (DMAPH) 6 [V 10 O 28 ]¨H 2 O, (1) and (DMAPH) 6 [V 10 O 28 ]¨16H 2 O, (2) (where DMAPH = 4-dimethylaminopyridinium) were obtained by reactions under mild conditions at T = 294 and 283 K, respectively. These compounds are pseudopolymorphs, which crystallize in monoclinic P2 1 {n and triclinic P1 space groups. The structural analysis revealed that in both compounds, six cations DMAPH interact with decavanadate anion through N-H¨¨¨O dec hydrogen bonds; in 2, the hydrogen-bonding association of sixteen lattice water molecules leads to the formation of an unusual network stabilized by decavanadate clusters; this hydrogen-bond connectivity is described using graph set notation. Compound 2 differs basically in the water content which in turn increases the 𨨨π interactions coming from pyridinium rings. Elemental and thermal analysis (TGA/DSC) as well as FT-IR, FT-Raman, for 1 and 2 are consistent with both structures and are also presented.

Frozen matrices of nitrogen containing Ga, In, and T1 atoms and ozone were prepared by matrix isolation techniques and studied by infrared absorption spectroscopy. Analyses of the spectra based on isotopic oxygen substitution have shown that the reagents yield the charge-transfer species M+O<, similar to the alkali-and alkaline-earth ozonides. Site-splitting perturbations produced several absorption bands for the u j vibration of the ozonide anion. These bands occurred in the region of -830-870 cm-I for the Ga and In species and in the region of 787-819 cm-' for the T1 species, despite similar relatively low ionization potentials for the metal atoms. It is suggested that decreased charge transfer owing to a degree of covalent bonding is responsible for the higher frequency bands of the gallium and indium ozonides.

groups on the ring nitrogens. Protons on nitrogen are known to produce broad N M R peaks at varied locations. The signals at -0.44 and 0.87 ppm are ascribed to the N H protons. Their relative ratio, 1 :2, is in agreement with the assignments; however, the ratio of the methyl protons to the nitrogen protons, 25.7:1, is much higher than the calculated value of 9:l. This could be due to peak broadening of the N H protons. The molecular weight of 2300 indicates the compound exists in solution in a polymeric form. Difficulty was experienced in solvent removal, and efforts to obtain crystals for X-ray structure determination were unsuccessful. The material exhibited only a single endotherm in the differential scanning calorimetry analysis at -275 OC. No endotherm was observed within the melting range. Thermolysis at 280 OC gave (Me3Si)2NH and ammonia; the ratio of the starting material to HN(SiMeJ2 to NH3 was found to be 1:0.6:0.1. From the above ratios, the large decrease in the infrared 11 IO-cm-I absorption, and the retention of the doublet at 3380 and 3290 cm-I, one is tempted to speculate that condensation took place via the NHSiMe3 substitutents. Pyrolysis up to 1000 "C of the low-temperature thermolysis product, using TGA, resulted in a black, shiny residue, pointing to carbon retention in agreement with the high ceramic yield. Conducting the final pyrolysis in a tube furnace, under an ammonia atmosphere, at 280-990 OC, gave a 37.7% ceramic yield, which is higher than the 24.65% calculated for pure AIN production.

Cyclometallated complexes of magnanese(1) with l-methylphenylimidazoles have been prepared. IR and 'H NMR spectroscopic studies show they are octahedral complexes in which the imidazole ligand is bound to the metal through the nitrogen and phenyl C(6) atoms. When the imidazole ligand with two phenyl groups at the C(2') and C(4') atoms is used, both possible cyclometallated compounds are obtained.

In this experiment, the thermal lens technique is used with a modified arrangement of three lasers to induce a two‐color absorption. Two‐pump lasers, a variable wavelength orange dye laser (588–617 nm), a single line blue laser (488 nm), and a single line probe yellow laser (568 nm) are employed. A comparison is made between the magnitude of the thermal lens signal obtained with a one pump laser versus two pump lasers. The absorbing molecules are benzene and naphthalene in liquid n‐Hexane. The CH vibrational overtone spectra are obtained at room temperature for several concentrations. The molecules are excited to a high vibrational state (Δυ = 6) with the first laser and to an electronic level with a second laser (two‐color absorption). Using two pump lasers, the limit of detection of the molecule is several orders of magnitude more sensitive than using one pump laser. A nonlinear behavior of the integrated signal versus concentration is shown for the two‐color laser process. Linea...

The reaction of the trigonal pyramidal Ni(0) complex [Ni(NP3)] (1) with CO in tetrahydrofuran (THF) solution has been re-investigated [NP3 = N(CH&H2PPh&]. Depending on the experimental conditions, the reaction gives either the monocarbonyl [Ni(03-NP3-P,P,P') (CO)] (2) or the dicarbonyl [Ni(q2-NP3-P,P)(C0)21 (3a). Both products exhibit a distorted tetrahedral coordination geometry; in the monocarbonyl complex, the NP3 ligand uses the three phosphorus atoms to bind the metal center, whereas it uses two phosphorus only in 3a. Compounds 2 and 3a have been characterized by IR and 31P and 13C NMR spectroscopies in both the solid state and solution. Compound 3a is thermally stable in the solid state under inert atmosphere even a t high temperature whereas, in ambient temperature solutions, it readily converts to 2 via CO elimination. The solid-gas reaction between crystals of 1 and CO (1 atm) a t room temperature gives a mixture of 2 and of a new species 3b, which has the same stoichiometry as 3a but exhibits a different 31P CPMAS spectrum. On dissolution in T H F saturated with CO, 3b converts to 3a whereas, under inert atmosphere, it dissolves to give initially 3a and later 2 and CO. In light of i n s i t u DRIFT and 31P CPMAS spectroscopies, 3b is suggested to be an ensemble of metastable species in which a phosphine arm from NP3, although unfastened, is located close to the metal center as a consequence of the constraining environment of the crystal lattice. The proximity of the free phosphine arm to nickel makes solid 3b capable of losing one CO ligand, thus converting to 2. Unlike in solution, the latter compound undergoes thermal dissociation of CO in the solid state to generate the starting complex 1.

Poly (aniline-co-o-anisidine) films were coated on Cu-40% brass electrodes using cyclic voltammetric conditions in a sodium oxalate solution with 0?06M aniline and 0?06M o-anisidine monomers at applied scan rates of 20 and 50 mV s 21 . Using this procedure, the surface of the electrodes was clearly covered with a black copolymer layer of strongly adherent homogeneous characteristics. In order to evaluate the corrosion performance of copolymer coated (CuZn/PANIco-POA) and uncoated electrodes in 3?5%NaCl, AC electrochemical impedance spectroscopy, anodic polarisation plots and open circuit potential-time curves were used. The copolymer films exhibited significant protection efficiency against the attack of corrosive agents and reduced drastically the corrosion rate of the brass.

X-ray diffraction and IR spectroscopic studies on cytosine trichloroacetate are reported. Cytosine is protonated at N (3 ) and each oxygen atom of trichloroacetate anion is engaged in tyo nearly linear hydrogen bonds: N(3)...0(1P)=2.755(5), N(4)...0(2P)=2.996(5) A, N(1)~~~0(2P)=2.843( )~andN( )~~~0(1P)=3.010(5)~.Thecarbonylgroupofcytosinedoes not participate in hydrogen bonding.

Phenylazoacetoacetanilide complexes of the type M(PAAC) n , where M is Zn(II), Hg(II), Mo(VI)O 2 , n is the valency of the metal, and HPAAC is Phenylazoacetoacetanilide (Butanamide 3oxo-N-phenyl-2-(phenyl hydrazono), have been synthesized and characterized. Complexes were isolated in solid state and characterized from elemental analysis, magnetic studies, UV-visible, IR and NMR data. The elemental analysis confirms the assigned stoichiometries. The stereochemistries of the complexes were ascertained using magnetic studies, uv-visible diffusive reflectance, IR and 1 H NMR. The present paper describes synthesis and characterization of these complexes. The complexes are found to have striking structural features. In these complexes, the phenylazo group (C 6 H 5 N 2 ) exibits bidentate character and co-ordinates with the metal through the phenylazo and methylketo groups. Metal: Ligand ratio is found to be 1:2. Mo (VI) complex shows the presence of O=M=O bond. Hence Zn (II), Hg (II) complex are tetrahedral and Mo (VI) complex is Octahedral in geometry.

Metal borohydrides are potential materials for solid-state hydrogen due to their high gravimetric and volumetric hydrogen densities. Among them, Ca(BH 4 ) 2 is particularly interesting because of the predicted suitable thermodynamic properties. In this work, we investigate a new synthesis route using high-pressure reactive ball milling. Starting from CaH 2 and CaB 6 with a TiCl 3 or TiF 3 as additive, a reaction yield of 19% is obtained after 24 h milling at room temperature and 140 bar H 2 . The presence of Ca(BH 4 ) 2 is confirmed by the presence of the stretching mode of the [BH 4 ] -group in the infrared spectra of the as-milled samples. Using in situ XRD, we observe the recrystallisation of a poorly crystallised Ca(BH 4 ) 2 phase present after milling. The reversible decomposition/formation of Ca(BH 4 ) 2 is obtained with higher yield (57%) using higher temperature and TiF 3 as additive but not with TiCl 3 despite its similar electronic structure. The differences observed using different additives and the influence of the anion are discussed.

This research was carried out to evaluate how alkali treatment of selected natural fibres (kenaf, luffa, betel nut, banana and rice straw) influences thermal properties, morphological properties and infrared spectrum properties of the composites made from polypropylene reinforced with natural fibres. Composites were made by compression moulding technique using hydraulic hot press. Composites were characterized by thermo-gravimetric analysis (TGA) to establish their thermal stability. The infrared spectrum of both treated and untreated natural fibres/PP composites were studied using Fourier transforms infrared spectrometer (FTIR). Infrared spectroscopy is sensitive to the presence of chemical functional groups in the composites. A functional group is a structural fragment within a molecule. Scanning electron microscopy (SEM) was used to investigate the morphology of composites. Increase in the thermal stability and better fibre-matrix compatibility of the composites were noticed in t...

Soils may constitute evidence that connects a person or object to a particular location. The value of soil stems from its ubiquity and transferability to objects or persons. Due to the complexity of soil, the analysis of its inorganic and organic components can provide complementary and independent types of information about its geological origin, dominant vegetation, management and environment. We present an overview of a range of soil characterisation methods including chemical analysis, mineralogy and palynology, along with new approaches such as DNA profiling and profiling of other digital data such as that obtained from X-ray powder diffraction, infrared spectroscopy and organic marker analysis. Individual analytical techniques have different scales of resolution and relevance depending on the nature of the criminal case and context. Each method has its strengths and weaknesses. As more methods have become digital and quantitative, their use in combination as digital profiles will help to characterise soils more accurately and at different scales. These new approaches can be tested using existing soil databases, and database development and use will help to refine and narrow probable origin of a questioned sample in police intelligence, as well as giving increasingly robust sample comparisons for evidence.

The chemical composition and nutritional content of garlic are greatly impacted by its production location, leading to distinct flavor profiles and functional properties among garlic varieties from diverse origins. Consequently, these variations determine the preference and acceptance among diverse consumer groups. In this study, purple-skinned garlic samples were collected from five regions in China: Yunnan, Shandong, Henan, Anhui, and Jiangsu Provinces. Mid-infrared spectroscopy and ultraviolet spectroscopy were utilized to analyze the components of garlic cells. Three preprocessing methods, including Multiple Scattering Correction (MSC), Savitzky-Golay Smoothing (SG Smoothing), and Standard Normalized Variate (SNV), were applied to reduce the background noise of spectroscopy data. Following variable feature extraction by Genetic Algorithm (GA), a variety of machine learning algorithms, including XGboost, Support Vector Classification (SVC), Random Forest (RF), and Artificial Neural Network (ANN), were used according to the fusion of spectral data to obtain the best processing results. The results showed that the best-performing model for ultraviolet spectroscopy data was SNV-GA-ANN, with an accuracy of 99.73%. The bestperforming model for mid-infrared spectroscopy data was SNV-GA-RF, with an accuracy of 97.34%. After the fusion of ultraviolet and mid-infrared spectroscopy data, the SNV-GA-SVC, SNV-GA-RF, SNV-GA-ANN, and SNV-GA-XGboost models achieved 100% accuracy in both training and test sets. Although there were some differences in the accuracy of the four models under different preprocessing methods, the fusion of ultraviolet and mid-infrared spectroscopy data yielded the best outcomes, with an accuracy of 100%. Overall, the combination of ultraviolet and mid-infrared spectroscopy data fusion and chemometrics established in this study provides a theoretical foundation for identifying the origin of garlic, as well as that of other agricultural products.

From 1983 to 1993, S. Hachi's last excavations at the Afalou Bou Rhummel (Algeria) Babors coastal shelter have contextually produced numerous anthropological and zoological, clay figurines, all hand made and cooked, among Iberomaurusian Late Upper Palaeolithic remains. Regarding Maghrebian territories (Morocco, Algeria, Tunisia and Libya), these so peculiar documents are strictly related to 15 000-11 000 BP levels, although deeper archaeological levels are 18 000 BP. Twenty eight small samples (less 1mg) were analysed through infrared absorption spectroscopy (IR) so as to precise, through typical transformation of the major mineral involved: kaolinite, smectites, and amorphous silicates, the final degree of temperature reached after cooking. These documents were all intentionally cooked between 500 and 800 °C. Local clay was obviously picked up for figurine elaboration.

Here we report on the electroactivity properties of Langmuir-Blodgett (LB) films of the hole-transport molecule 4,4´,4´´-tris [3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA). Fairly stable Langmuir films at the air-water interface are accomplished, despite the non-amphiphilic character of the molecule. The Reflection-Absorption Infrared Spectroscopy (RAIRS) and Fourier Transform Infrared (FT-IR) analysis revealed that the molecules arrange with no neat preferential orientation, in agreement with the amorphous glassy nature of this starburst molecule. However, there is a tendency of the molecules to organize in a more planar conformation due to the intermolecular stacking induced by the LB technique. On the other hand, the fundamental electrochemistry (by Cyclic Voltammetry, CV) of the films is also analyzed. The CV studies of both solution and films reveal that both the solid Wavelength / nm Wavelength / nm m m--MTDATA MTDATA electrooxidization Wavelength / nm Wavelength / nm m m--MTDATA MTDATA electrooxidization state and the electrolyte's anions clearly affect the m-MTDATA's electroactivity, exhibiting a unique and broad redox process instead of the two reversible oxidations observed in solution. The oxidization mechanism is discussed. Finally, the spectroelectrochemistry studies evidence that the oxidization of the films leads to new absorption bands, among which it should be pointed up the emerging bands in the NIR region ascribed to intervalence charge transfer (IVCT) between the generated aminyl radical cations.

A series of novel organoiron complexes has been isolated and studied by 'H NMR, 13C NMR, and IR spectroscopy. Addition of LiC(CHJ)&N to (1,3-cyclohexadiene)tricarbonyliron produces an intermediate which is only stable at low temperature and which is assigned the homoallyl-Fe(CO)J anion structure. The intermediate rearranges on warming into a stable complex, for which full spectral data support the structure as an allyl-Fe(CO)j anionic species. Interception of the first formed intermediate with CO gives an acylferrate complex with an olefin unit still bound to iron, and methylation then occurs at oxygen to produce an unusual internally-bound (alkene)(methoxyalkylidene)tricarbonyliron species.

Antecedentes: Entre los múltiples métodos propuestos para predecir la presencia de fibrosis en los pacientes con hepatitis crónica por virus C, están los índices obtenidos a partir de pruebas bioquímicas en suero (índice de la relación AST/plaquetas [APRI]; índice de Forns [IF]). Objetivo: Comparar la certeza diagnóstica del IF y APRI para predecir la presencia de fibrosis. Métodos: Se incluyeron 105 pacientes con hepatitis crónica por VHC y biopsia hepática. A partir de las pruebas bioquímicas de cada paciente se calculó el IF y APRI. Se construyeron curvas operativas ■ Abstract

XPS (X-ray photoemission spectroscopy) and IR (infrared) analyses of poly(3-methylthienylene) films, electrochemically or chemically redoped with various chemical species at varying doping levels, have been investigated. On the basis of these results, the major chemical species of dopants have been identified. As a result, the dopant content was determined and the poly(3-methylthienylene) films were classified as light or heavy by doping level. The conductivity ranged from about 10 -'2 to 10 2 S cm -1 for all the films investigated. The conductivity and the activation energy of conduction for the heavily<loped films vary as a function of the dopant content, independent of the different chemical species of dopants. In particular, a sudden change is observed in the dependence of activation energy on dopant content. This sudden change may be associated with the semiconductor-metal transition. Furthermore, it is shown that the specific absorption bands in the infrared are induced by the doping, intensified with increasing dopant uptake and accompanied by an increase in conductivity.

Cu(II), Co(II) and Ni(II) complexes of chelating resins (CR) bearing iminodiacetate (IDA) ligands were prepared. The CR-metal complexes were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), thermal behavior (TG and DTG) under nitrogen atmosphere, and electron paramagnetic resonance (EPR). FT-IR spectra of the CR-metal complexes showed the characteristic bands of CR were still present but red-shifted after the metal complexation, and new bands assigned to Me-N bonds were observed. Thermal behavior of the metal-CR complexes supported the metal complexation, metal complexation leading to the decrease of the thermal stability of the CR, the lowest thermal stability being found when the highest amount of Cu(II) was loaded. Based on the EPR results and the thermal behavior of Cu(II)-CR complexes, the scheme for the complexation of Cu(II) on the CR was suggested.

The two dimensional (2D) to three dimensional (3D) transition for the protonated water cluster has been controversial, in particular, for H+(H2O)7. For H+(H2O)7 the 3D structure is predicted to be lower in energy than the 2D structure at most levels of theory without zero-point energy (ZPE) correction. On the other hand, with ZPE correction it is predicted to be either 2D or 3D depending on the calculational levels. Although the ZPE correction favors the 3D structure at the level of coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)] using the aug-cc-pVDZ basis set, the result based on the anharmonic zero-point vibrational energy correction favors the 2D structure. Therefore, the authors investigated the energies based on the complete basis set limit scheme (which we devised in an unbiased way) at the resolution of the identity approximation Møller-Plesset second order perturbation theory and CCSD(T) levels, and found that the 2D structure ha...

Introduccion: La elastosonografia en tiempo real por onda de cizalla (SWE) es una prueba no invasiva utilizada para determinar la rigidez hepatica en pacientes con hepatopatias de diferentes etiologias, lo que permite graduar enestadios la severidad de la fibrosis. En algunas ocasiones, reemplaza la toma de biopsia y es util para seguimiento. En Uruguay, la prueba se introdujo recientemente y no existen hasta el momento estudios de su comportamientoen personas sanas. Materiales y metodos: Estudio transversal, prospectivo, en 22 voluntarios sanos elegidos por conveniencia, tras firma de consentimiento informado. Dos observadores con diferentes niveles de experiencia midieron la rigidez hepatica con SWE, en dos ecografos de distintas marcas comerciales. Resultados: La serie incluyo 22 voluntarios sanos, con edad promedio de 32 anos. La media de rigidez hepatica obtenida para el equipo marca comercial Phillips® y Toshiba®, fue de 5.06 y 5.85 kPa respectivamente. El coeficiente de corre...

Treatment of various substituted semicarbazones of aromatic aldehydes with sulfur monochloride yields the corresponding substituted 2,4‐dihydro‐1,2,4‐triazol‐3‐ones. With thiosemicarbazones, the products are derivatives either of the 2‐amino‐1,3,4 thiadiazole or of the 2,4‐dihydro‐1,2,4‐triazole‐3‐thione depending on the experimental conditions.

Within the family of small carbon clusters, C, has received a particularly notable amount of attention.* Beginning with the extended Huckel calculations of Pitzer and Clementi in 1958,' many ab initio calculations have addressed the structures and energetics of the two most stable isomers.3-13 The most sophisticated calculations now agree that the bicyclic rhombus ('A,) structure and the linear

Synthetic access to the zerovalent palladium complexes {[(o-Ph 2 PC 6 H 4) 2 BPh]Pd(L)} (L = pyridine (8a), 2,6-lutidine (8b)) is reported. Structural characterization and DFT analysis of 8a revealed a strong Pd→B interaction, which appears to inhibit oxidative addition reactions. Activation of allyl acetate is possible by reversible transfer of the acetate leaving group to the ligand's borane functionality. Catalytic activity in the allylic substitution of allyl acetate with HNEt 2 is sensitive to the presence of free acetate, which reduces borane inhibition by reversible borate formation.

Fourier-transform infrared (FT-IR) spectra of yeast ribosomal 5 s RNA have been acquired at several temperatures between 30 and 90 OC. The difference spectrum between 90 (bases unstacked) and 30 "C (bases stacked) provides a measure of base stacking in the RNA. Calibration difference spectra corresponding to stacking of G-C or A-U pairs are obtained from "reference" FT-IR spectra of poly-(rG).poly(rC) minus 5'-GMP and 5'-CMP or poly(rA).poly-(rU) minus 5'-AMP and 5'-UMP. The best fit linear com-O n e 5 s RNA molecule is a required constituent for protein synthesis in virtually every studied prokaryotic or eukaryotic ribosome (Erdmann, 1976). "lie primary nucleotide sequences of more than 50 5s RNAs have been determined (Erdmann, 1982). Because of the apparent universal function of 5s RNA, it is widely speculated that all 5 s RNAs share a common secondary structure. (For example, reconstitution of 5 s RNA from one prokaryote with the remaining ribosomal components from a different prokaryote leads to functional ribosomes.) Thus, the determination of a 5 s RNA secondary structure for even a single species would have broad implications for 5 s RNA structure in other species. Although a "cloverleaf" secondary structure is universally accepted for all known transfer RNAs, there is as yet no agreement on a universal secondary structure for any of the larger RNAs. For ribosomal 5s RNA, for example, literally dozens of secondary structures have been proposed (Erdmann, 1976; Appel et al., 1979). Secondary structure is generally deduced from two complementary types of experiments. The first type (e.g., nuclease cleavage, chemical modification, oligonucleotide binding) typically identifies single-stranded bases or segments. The second type (e.g., differential scanning microcalorimetry and 'H Fourier-transform nuclear magnetic resonance, infrared, Raman, and ultraviolet spectrometry) counts and identifies paired or stacked bases. In addition, the gross shape of the macromolecule can be guessed from light scattering, low-angle X-ray scattering, and circular dichroism (CD) measurements. For 5 s RNAs, most published experiments are of the first type. Only recently have the spectroscopic techniques begun to be applied to 5s RNAs. Although UV spectra of polynucleotides are sensitive to base stacking, analysis for the proportion of individual base-pair types (e.g., G-C vs. A-U vs. G-U) can be obscured by the high degree of overlap between spectra for each of the various bases or base pairs. As noted in a recent review (Carey, 1982), Raman and infrared spectra share the advantage that bands associated with individual bases (A, G, C, U) are at least partly From the Department of Chemistry (K.O.B. and A.G.M.), the Department of Biochemistry (A.G.M.), and the Department of Physiological Chemistry (J.O.A.

Electron spin resonance, ionic thermostimulated current, and infrared absorption measurements are reported for Brazilian natural sodalite. We have found a paraelectric center exhibiting two relaxation processes, which can be converted into a paramagnetic one when the sample is exposed to X irradiation. Infrared absorption bands associated with this center led us to identify it as a complex carbonate. The sensitization process for natural sodalite is also discussed.

The direct electrochemical oxidation of coal gas was studied by pyrolyzing a sample of Ohio #5 coal in flowing Ar at 700, 800, 900, and 950°C and transporting the resulting gaseous products to a Cu (Copper) anode solid oxide fuel cell (SOFC) operated at 950°C. Pyrolysis of coal at 700°C produced a H 2-rich coal gas containing 89% H 2 , 4% CO, 6% CH 4 , 1% CO 2 , and sulfur compounds (i.e., 1% COS and 1% SO 2), which yielded a maximum current density of 320 mA/cm 2 at 0.5 V. Raising the pyrolysis temperature from 700 to 950°C increased the CO concentration in the coal gas (i.e., 42 vol % CO), which in turn reduced the fuel cell maximum current density. No sulfur compounds were present in the coal gas produced at temperatures higher than 700°C. Coal gas fuel operation did not degrade the fuel cell performance. A fuel composition of 25 vol % CH 4 in He generated a current density of 340 mA/cm 2 at 0.5 V. These results demonstrated that the Cu anode is effective for the electrochemical oxidation of sulfur-containing coal gas at 950°C. The addition of CO 2 and D 2 O to the pyrolysis reactor led to the formation of CO and HD, indicating the occurrence of reforming reactions. Diffuse reflectance infrared Fourier transformation (DRIFT) spectra showed that coal pyrolysis proceeded by dehydrogenation of hydroaromatics, dealkylation of aromatics, and oxidation reactions, leading to the formation of coke with a surface containing CO , C-S, and SO bonds. The results of the fuel cell performance strongly support the feasibility of direct power generation from coal gas in a Cu-anode SOFC.

The neutral-component complexes (HCOOH)3•(18-crown-6)2, (CH3COOH)2•18-crown-6, and various halogenated CH3COOH/18-crown-6 adducts have been isolated and studied by infrared and Raman spectroscopy. The halogenated (F, Cl, and Br) derivatives, which occur as (acid•water)x•18-crown-6(x = 1 or 2) adducts, probably have a structure which is similar to that of the known CH2(CN)COOH•H2O•18-crown-6 complex.

The pyridinium chlorochromate oxidation of six bis(trimethylsily1) and six bis(tert-butyldimethylsilyl) ethers of p-hydroquinones at room temperature in methylene chloride solution gave the corresponding quinones in 6040% yield. The bis(trimethylsily1) ethers were slightly more reactive than the bis(tert-butyldimethylsilyl) ethers. High oxidation efficiency was indicated by a 1:l molar stoichiometry; however, more convenient reaction times were obtained at a 2:l molar ratio of pyridinium chlorochromate (PCC) to hydroquinone silyl ether. The mechanism is discussed based upon comparisons of relative reaction rates with electrochemical oxidation potentials.

tored by i.r. spectroscopy. When the v(CO) absorptions of [Fe(CO)4PR~] had disappeared, irradiation was stopped. Reaction time decreases with an increasing number of chlorine substituents at silicon. The reaction mixture was then filtered. From the clear yellow filtrate, all volatile components were removed in vacuo. The remaining pale yellow-to-brown residue was extracted several times with hot hexane or hexane/ benzene 2 : 1. On cooling the combined solutions to 0 ~ the hydrido-silyl complexes precipitated as pale yellow solids. If necessary, they were recrystallized from hexane or hexane/ benzene. Elemental analyses, melting points and yields are given in Table 3. Yields were not optimized.

The vibrational spectra of seven of the inositol isomers and of some of their hydroxyl deuterated counterparts were investigated and were interpreted on the basis of comprehensive normal-coordinate analysis. The spectra of six molecules, scyllo-inositol, neo-inositol, rnyo-inositol, epi-inositol, deuterated scyllo-inositol, and deuterated neo-inositol, were used as the basis for developing a 33-parameter force field which was refined to give the best fit to the experimental spectra by using the Fletcher-Powell nonlinear least-squares algorithm. For these six inositols the overall average error was 10.4 cm-' for 234 assigned frequencies. The generality of the force field was established by its successful use in predicting the vibrational frequencies for cis-inositol, L-chiro-inositol, and rnuco-inositol, which were not included in the force constant refinement; the average errors were only slightly higher than those obtained for the other inositols. The calculated potential energy distributions showed a majority of the vibrations to be composed of complex atomic motions with extensive coupling of the different motions typically occurring below 1500 cm-I. A group of temperature-sensitive bands observed in the region between 300 and 750 cm-I in the spectra of all the inositols was interpreted as modes involving the deformations of the hydrogen-bonded hydroxyl hydrogens. These bands were not assigned and could only be reproduced by inclusion of intermolecular potentials in the molecular models.

We report recent advances on the spectral control of continuous-wave-pumped supercontinuum sources. We show that the generated infrared SC spectrum can be tailored by using photonic crystal fibers with two zero-dispersion wavelengths. The dynamics of the spectral broadening is studied, and we show that slightly different nonlinear mechanisms occur as the zero-dispersion wavelengths are brought closer to each other. We also report the generation of a visible continuous-wave-pumped supercontinuum by using dispersion engineered photonic crystal fibers in which the zero-dispersion wavelength slightly decreases as a function of length over 200 m. The resulting supercontinuum source spans from 650 nm to 1380 nm with an average output power of 19.5 W. The nonlinear mechanisms producing this spectacular effect are carefully investigated with support of numerical simulations. We show that the generation of visible wavelengths is due to the trapping of dispersive waves by powerful red-shifting solitons.

Aluminum nitride is grown on an alumina substrate by several sequential exposures to trimethyl aluminum and ammonia. Broad similarities are evident between the chemistry in this case and that found for the reaction between trimethylaluminum and water except that temperatures of in excess of 500 K are required to form AlN layers whereas alumina is formed at room temperature. It is found, using infrared spectroscopy to examine the surface species formed during repeated sequential adsorption of trimethylaluminum and ammonia, that trimethylaluminum initially reacts to form an adsorbed dimethylaluminum species. This reacts with ammonia to initially form a Lewis acid-base adduct which subsequently reacts to form bridging and terminal NH 2 species. The first methyl group in the adsorbed species is found to be more reactive than the second, an effect that was also noted for reactions with water. The ultimate formation of AlN films by several sequential exposures to trimethylaluminum and ammonia is confirmed using X-ray photoelectron spectroscopy and gravimetrically by weighing the samples after several trimethylaluminum and ammonia exposure cycles.

FT IR and FT Raman spectra of Ag 3 (PO 2 NH), (Compound I), Na 3 (PO 2 NH) 3 .H 2 O (Compound II), Na 3 (PO 2 NH) 3 .4H 2 O (Compound III), [C(NH 2) 3 ] 3 (PO 2 NH) 3 .H 2 O (Compound IV) and (NH 4) 4 (PO 2 NH) 4 .4H 2 O (Compound V) are recorded and analyzed on the basis of the anions, cations and water molecules present in each of them. The PO 2 NH − anion ring in compound I is distorted due to the influence of Ag + cation. Wide variation in the hydrogen bond lengths in compound III is indicated by the splitting of the 6 2 and 6 3 modes of vibration of water molecules. The NH 4 ion in compound V occupies lower site symmetry and exhibits hindered rotation in the lattice. The correlations between the symmetric and asymmetric stretching vibrations of P N P bridge and the P N P bond angle have also been discussed.

The present research aims to design the new dyes with a D-π-A structure to apply Dye-sensitized solar cells. The D-π-A dyes constitute S1 to S9, using 9-vinyl-9H-carbazole (D) as a donor (D); different thiophene derivatives are π-spacers and cynoacrylic acid is an acceptor.For the electronic and optical properties calculation of the studied dyes, use DFT/B3LY-P/6-311G++ levelof theory by using Gaussian 09W software. Using optimized geometrical structures to calculate the UV absorption spectra, utilize the TD-DFT method in the gas and acetonitrile solvent. The HOMO and LUMO energy gap (Eg) values of S5 and S9 dyes show a narrow band gap with 1.8 eV and 1.7 eV, respectively. So all studied dyes have LUMO values higher than the TiO2 conduction band and HOMO values lower than the electrolyte redox potential.The UV absorption spectral data shows S5 and S9 have maximum absorption at 759 nm and 803 nm,respectively.So all the studied dyes are suitable for DSSC application.

Glass sample compositions of xCaO(1-x-z)-SiO 2 zB 2 O 3 with constant nominal CaO of x=33.33 mol% and varying concentrations of B 2 O 3 as z=50,60 and 66.67 mol% are prepared by conventional melt quench technique. Fourier transform infrared (FTIR) spectra of xCaO(1-x-z)-SiO 2 zB 2 O 3 glass system has been measured in the spectral range 400-4000 cm −1 low-frequency region 1700cm-1 to 400cm-1 and highfrequency region 4000cm-1 to 1700cm-1) at room temperature to understand the characteristic frequencies of the chemical bonds, bonding mechanisms and structure of electron shell of atoms, for the purpose to determine the molecular structure of the composition. It is found that the melting temperature of the glasses decreases with the increase of B 2 O 3 concentration and the melting temperature in the range of 950 o C-1100 o C for the samples which consist of 50, 60, and 66.67 mol% of B 2 O 3. In the low-frequency region (1700cm-1 to 400cm-1) the spectra of high B 2 O 3 containing glass showed an increased number of distinct peaks and several broad Gaussian in the thighfrequency region (1700cm-1 to 400cm-1). All the spectra are based on line corrected and deconvoluted to the appropriate number of Gaussians. Fourier transform infrared (FTIR) deconvoluted spectra were analyzed to determine the exact position and relative amounts of the IR bands responsible for the different silicate borates units. The distinct peaks and peak position of the deconvoluted Gaussians are assigned to Si-O-Si, B-O-B, Si-O-Ca, Si-O etc. bonds based on the previous scientific investigations. The presence of B 2 O 3 in the materials suggests that B 3+ occupies the network position and for the linkage Si-O-B in the glasses. The amorphous nature, the surface topography and composition of the prepared glasses was checked by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques respectively on optical inspection, did not show any evidence of phase separation, and all glasses are homogeneous.