Ultraviolet spectroscopic study of ferric hydroxide complexation

Ultraviolet absorbance spectra of ferric ions in 0.68m NaClO₄ were studied as a function of pH at 4.0, 14.9, and 25.0°C. The results provided an evaluation of the stability constant for the formation of FeOH²⁺ which is *₁=[FeOH ⁺][H ⁺]/[Fe ³⁺]. The enthalpy change for the reaction Fe³⁺+H₂O FeOH²⁺+H⁺ was calculated as 10.0±0.3 kcal-mole^–1. Increasing temperature was also found to promote the reaction Fe³⁺+2H₂O Fe(OH) ₂ ⁺ +2H⁺. Our results were combined with the results of other to produce an expression describing the first hydrolysis equilibrium at ionic strengths between 0 and 3m and temperatures between 4.0 and 45.0°C at 1 atm total pressure. At 25°C and 0.68m the ionic strength *₁=1.90×10^-3     

Ultraviolet photoelectron spectroscopic study on the interface electronic structure of the L-cysteine on Pd surface

L-cysteine is one of the most versatile biomolecules with a unique metal-binding ability. L-cysteine has an outstanding role in the bioelectronics field as a linker between proteins of biomolecules and metal electrodes of the inorganic metals through multiple functional groups. The interface electronic structures between L-cysteine with metals deserve further investigation for applications in bioelectronics. However, the interface electronic structures of L-cysteine and metals have not been well understood. We have previously reported the existence of a new state between the highest occupied molecular orbital (HOMO) of L-cysteine and the Fermi level of the metals for L-cysteine/Au(111), L-cysteine/Ag(111), and L-cysteine/Cu(111) using photoemission spectroscopy and attributed the formation of the new state to an interaction of the d band with HOMO of L-cysteine. In this study, the electronic structure at the interfaces of L-cysteine on a Palladium (Pd) surface is investigated by ultraviolet photoemission spectroscopy (UPS) using synchrotron radiation including work function, secondary electron cutoff (SECO), and HOMO onset; the position of an interface state, charge injection barrier, and ionization energy are estimated. It is observed that thin-film spectra of L-cysteine on Pd surfaces in the valance top region are different from the L-cysteine thick films, and this can be attributed to an interaction between a sulfur-originated state of L-cysteine HOMO with Pd d orbitals. Also, a 0.6-eV SECO shift is estimated due to the charge transferring between L-cysteine and Pd. The results of SECO further confirm the weakening of the Pd–sulfur bond with increasing L-cysteine coverage on Pd.     

Ultraviolet spectroscopic study of ferric equilibria at high chloride concentrations

The equilibria among the species Fe³⁺, FeCl²⁺, FeCl₂ ⁺, FeOH²⁺ and Fe(OH)₂ ⁺ have been examined by ultraviolet absorption spectroscopy. Our results indicate that previous workers have generally overestimated the stability constant of FeCl²⁺ and that the association of Fe³⁺ and Cl^– is predominantly inner sphere. The formation constant of FeOH²⁺ obtained in 0.68 m NaCl is in good agreement with our earlier results obtained in 0.68 m NaClO₄. Our results indicate that formation of FeOHCl⁺ is much less significant than has been previously reported. Molar absorptivities for the species Fe³⁺, FeCl²⁺, FeCl₂ ⁺ and FeOH²⁺ are reported for wavelengths between 220 and 400 nanometers.     

Infrared spectroscopic study of the interactions of nylon‐6 with water

We studied the interactions of nylon‐6 with water by following the Fourier transform infrared spectra of a hydrated thin film during dehydration. Very small changes in the spectra caused by the interactions were clearly revealed by the application of spectral subtraction. The water was found to interact with amide groups to form hydrogen bonds with non‐hydrogen‐bonded or free C?O and NH groups in the amorphous portion in the first hydration sphere. This was deduced from an analysis of minus and plus peaks appearing around the absorptions of the NH stretching, amide I band, and amide II bands in the difference spectra between the spectra during dehydration and the one at the most dehydration. The interactions of the amide groups with water were significantly stronger than the hydrogen bond between CO and NH in the crystalline portion, according to the magnitude of the frequency shift of relevant bands. Water, as the interacting counterpart, showed a distorted OH stretching absorption with two close peaks at about 3450 cm^?1. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1722–1729, 2003     

Production of cellulase in solid-state fermentation withTrichoderma reesei MCG 80 on wheat straw

Applied Biochemistry and Biotechnology - It is an accepted fact that ethanol production from lignocellulosic materials is not economical as yet because of the high cost of cellulase production. To...     

Millimeter spectroscopic study of intermolecular interactions in solutions

The absorption of 5 cm^–1 electromagnetic radiation by aqueous solutions of methyl, ethyl, n-, and isopropyl, sec-, iso-, and tert-butyl, and tert-amyl alcohols and ethylene glycol was measured within their solubility limits in water at 20°C. It was found that the observed nonadditivity of absorption (absorption deficit) is a qualitative measure of hydration of alcohols of two types: hydrophilic and hydrophobic. The possibility of distinguishing these effects by millimeter spectroscopy was demonstrated. Hydrophobic hydration makes the basic contribution to the hydration number of aliphatic alcohols. On the example of solutions of ethanol and tert-butanol, it was shown that hydrophobic hydration decreases with an increase in the temperature of the solution due to intensification of hydrophobic interactions between the hydrocarbon radicals.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1755–1761, August, 1989.     

Fourier-transform infrared spectroscopic study of the interactions of selenium species with living bacterial cells

A study of the interactions of several selenium species with living bacterial cells was carried out by Fourier-transform infrared (FT-IR) spectroscopy. Bacterial cells consisted of an Escherichia coli strain (K-12) cultivated in a growth medium based on glucose contaminated with selenium species. Equilibrium between the analyte in the solution and the extraction medium was established, and then the effects of selenium species upon the external membrane of the living bacterial cells were characterized by performing FT-IR spectroscopy of whole cells. The presence of the toxicants at various concentrations in the culture medium had an effect on the FT-IR spectra, and the concentration of the selenium species was determined directly in the biomass by FT-IR spectroscopy. The intensity ratios between several absorption lines, which varied as a function of the concentration of the selenium species, were used as the analytical signal.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

Effect of acetic acid and furfural on cellulase production of Trichoderma reesei RUT C30

Because of the high temperature applied in the steam pretreatment of lignocellulosic materials, different types of inhibiting degradation products of saccharides and lignin, such as acetic acid and furfural, are formed. The main objective of the present study was to examine the effect of acetic acid and furfural on the cellulase production of a filamentous fungus Trichoderma reesei RUT C30, which is known to be one of the best cellulase-producing strains. Mandels’s mineral medium, supplemented with steam-pretreated willow as the carbon source at a concentration corresponding to 10 g/L of carbohydrate, was used. Four different concentration levels of acetic acid (0–3.0 g/L) and furfural (0–1.2 g/L) were applied alone as well as in certain combinations. Two enzyme activities, cellulase and β-glucosidase, were measured. The highest cellulase activity obtained after a 7-d incubation was 1.55 FPU/mL with 1.0 g/L of acetic acid and 0.8 g/L of furfural added to the medium. This was 17% higher than that obtained without acetic acid and furfural. Furthermore, the results showed that acetic acid alone did not influence the cellulase activity even at the highest concentration. However, β-glucosidase activity was increased with increasing acetic acid concentration. Furfural proved to be an inhibiting agent causing a significant decrease in both cellulase and β-glucosidase production.     

Trans-annular interactions in morpholines: A photoelectron spectroscopic study

The He I and He II photoelectron spectra of 4-methylmorpholine, 4-morpholinecarbonitrile, and 4-morpholinepropionitrile have been measured. The electronic structure and heteroatom lone pair interactions, in particular, were analyzed with the aid of HeII/HeI intensity variations, comparison with the spectra of related compounds, and AM1 semiempirical calculations. We present an example of combined inductive and resonance interactions operating in the morpholine ring system.     

Visualization of cellulase interactions with cellulose microfibril by transmission electron microscopy

In this study, we developed a method to observe interactions between cellulase and cellulose microfibril by transmission electron microscopy. Although negative staining and low-angle metal shadowing increase image contrast, neither method is sufficient to view enzyme interactions with microfibril. However, we found that the combination of negative staining and low-angle metal shadowing provided better contrast for enzyme-like particles on the microfibril. The lengths of the particles interacting with microfibrils were 7.03 and 5.05 nm, parallel and perpendicular to the fiber direction, respectively. Accounting for the additional thickness owing to metal shadowing, the particle sizes were consistent with that of CBH I from Trichoderma reesei based on a crystalline structural analysis. The combination of these electron staining techniques successfully visualized morphological changes in microfibril as well as enzymes adsorbed on it, thus demonstrating cellulase in action. These results indicate that appropriate staining techniques can be applied to extend the applications of transmission electron microscopy, which may be particularly beneficial for studies on enzymatic behavior.     

Multinuclear NMR spectroscopic and theoretical study on the interactions between diperoxovanadate complex and picoline-like ligands

To understand the substituting effects of organic ligands on the reaction equilibrium, the interactions between diperoxovanadate complex [OV(O(2))(2)(H(2)O)](-) and a series of picoline-like ligands in solution were explored using 1D multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, 2D diffusion ordered spectroscopy (DOSY), and variable temperature NMR in 0.15 mol/l NaCl ionic medium for mimicking the physiological conditions. The order of reactive capability of the picoline-like ligands with [OV(O(2))(2)(H(2)O)](-) is found to be picolinamide>N-methylpicolinamide>methyl picolinate>ethyl picolinate approximately propyl picoliniate>isopropyl picolinate. The substituting group influences the reactivity by either steric effect or electron-donating effect. Competitive coordination interactions result in a series of new seven-coordinated peroxovanadate species [OV(O(2))(2)L](-) (L=picoline-like ligands). Their coordination ways were confirmed by density functional calculations.     

Production of cellulase/β-glucosidase by the mixed fungi culture of Trichoderma reesei and Aspergillus phoenicis on dairy manure

A cellulase production process was developed by growing the fungi Trichoderma reesei and Aspergillus phoenicis on dairy manure. T. reesei produced a high total cellulase titer (1.7 filter paper units [FPU]/mL, filter paper activity) in medium containing 10 g/L of manure (dry basis [w/w]), 2 g/L KH₂PO₄, 2 mL/L of Tween-80, and 2mg/L of CoCl₂. However, β-glucosidase activity in the T. reesei-enzyme system was very low. T. reesei was then cocultured with A. phoenicis to enhance the β-glucosidase level. The mixed culture resulted in a relatively high level of total cellulase (1.54 FPU/mL) and β-glucosidase (0.64 IU/mL). The ratio of β-glucosidase activity to filter paper activity was 0.41, suitable for hydrolyzing manure cellulose. The crude enzyme broth from the mixed culture was used for hydrolyzing the manure cellulose, and the produced glucose was significantly (p<0.01) higher than levels obtained by using the commercial enzyme or the enzyme broth of the pure culture T. reesei.     

Fourier transform infrared spectroscopic and theoretical study of water interactions with glycine and its N-methylated derivatives

In this study we attempt to explain the molecular aspects of amino acids' hydration. Glycine and its N-methylated derivatives: N-methylglycine, N,N-dimethylglycine, and N,N,N-trimethylglycine were used as model solutes in aqueous solution, applying FT-IR spectroscopy as the experimental method. The quantitative version of the difference spectra method enabled us to obtain the solute-affected HDO spectra as probes of influenced water. The spectral results were confronted with density functional theory calculated structures of small hydration complexes of the solutes using the polarizable continuum model. It appears that the hydration of amino acids in the zwitterionic form can be understood allowing a synchronized fluctuation of hydrogen bonding between the solute and the water molecules. This effect is caused by a noncooperative interaction of water molecules with electrophilic groups of amino acid and by intramolecular hydrogen bond, allowing proton transfer from the carboxylic to the amine group, accomplishing by the chain of two to four water molecules. As a result, an instantaneous water-induced asymmetry of the carboxylate and the amino group of amino acid molecule is observed and recorded as HDO band splitting. Water molecules interacting with the carboxylate group give component bands at 2543 ± 11 and 2467 ± 15 cm(-1), whereas water molecules interacting with protons of the amine group give rise to the bands at 2611 ± 15 and 2413 ± 12 cm(-1). These hydration effects have not been recognized before and there are reasons to expect their validity for other amino acids.     

Production of cellulase systems by selected mutants ofTrichoderma reesei in solid-state fermentation and their hydrolytic potentials

Applied Biochemistry and Biotechnology - Three mutants ofTrichoderma reesei were grown in solid-state fermentation (SSF) in flasks and in a pan bioreactor. Mutant strain MCG 80 proved to be best at...     

A spectroscopic study of atomic interactions in aryl derivatives of group iv elements

Spectroscopic features (quantitative IR, Raman, and UV spectra) are discussed for group IV (M=C, Si, Ge, Sn) aryls, mainly R₃MC₆H₅ and R₃MCH₂C₆H₅, in order to distinguish features of the intramolecular interactions. Confirmation is obtained for the existing view on the electron-acceptor behavior of heteroatoms joined to aromatic rings. The effect is seen in the IR and UV spectra, which implies that the ground and excited states are perturbed. The effect of M on the ring is shown to be an over-all one; the positive (induction) component follows the electronegativity of M in a scale close to Gordy's, while the negative one increases somewhat from Si to Ge and Sn.The effects in M aryls are analogous to those in M alkenyls, in particular the - conjugation in a phenyl radical attached to Si, which is already known for M allyls.     

Nitrogen lone pair interactions in organic molecules: a photoelectron spectroscopic study

The electronic structure of several cyclic, saturated and unsaturated amines and imines has been investigated by UV photoelectron spectroscopy (UPS). The analysis of spectra has been performed with DFT and OVGF calculations and comparison with the UPS spectra of related compounds. The extent and type of nitrogen lone pair interactions is discussed because nitrogen lone pairs are the most important functional groups present in these molecules. The magnitude of interactions was found to depend on the spatial orientation and rigidity of mutual positions of the lone pairs, rather than on their spatial distance.     

IR spectroscopic study of ion-molecular interactions in the methanesulfonic acid—N,N-dimethylformamide system

Complex formation in the methanesulfonic acid (MSA)-DMF system was studied by Multiple Attenuated Total Reflectance (MATR) IR spectroscopy at 30°C within the composition range from neat MSA up to neat DMF. Depending on the ratio of components, two types of complexes with a strong quasi-symmetrical H bond (1 and2) are formed. The uncharged complex1 is a quasi-ion pair with the (O…H…O) bridge. Complex2 is formed by a protonated DMF molecule and the (A…H…A)⁻ anion bound as an ion pair. It is established that complexes1 are solvated by DMF molecules in an excess of a base. Solvation or2 in an excess of an acid corresponds to a change from contact to contact-separated ion pairs. Continuous absorption spectra of charged and uncharged complexes1 and2 were obtained. The schemes of acid-base interactions in the MSA-DMF and HCl-DMF systems were compared. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2484–2489, December, 1998.     

Molecular spectroscopic study on the interaction of tetracyclines with serum albumins

A molecular spectroscopic investigation of the interaction between tetracyclines antibiotics and human serum albumin or bovine serum albumin was reported. The influences of some metal ions on the interaction were also studied. When tetracyclines drugs were added into the solution containing serum albumins, the fluorescence intensity of serum albumins decreased with the increasing of the drugs concentrations, which is due to the formation of new non-fluorescence complexes of drug-serum albumin. The tetracyclines acted as quenchers and quenched the fluorescence of the serum albumins. The binding constants and the number of the binding sites of the reaction of tetracyclines and serum albumins were obtained. The main sorts of acting force between the drugs and serum albumins were found and the action distances and the energy transfer efficiencies between donor-acceptor were calculated based on the Foster energy transference.     

几种金属离子对胭脂红与牛血清白蛋白相互作用的影响——荧光光谱研究

利用荧光光谱法研究了不同温度(15、27、39℃)下食用合成色素胭脂红对牛血清白蛋白(BSA)的内源荧光猝灭特性,考察了Cu2+、Ni 2+、Pb2+等金属离子对二者相互作用的影响,并测定了不同温度下的猝灭常数KSV、结合常数KA和结合位点数n.结果表明,3种金属离子基本不影响胭脂红对BSA荧光猝灭机理,但Cu2+、Ni 2+、Pb2+离子都与BSA有一定的结合能力,可在不同程度上增强胭脂红与BSA的结合作用及其对BSA内源荧光的猝灭.