Control the orbital angular momentum in third-harmonic generation using quasi-phase-matching.

Manipulating photon's orbital angular momentum (OAM) through nonlinear interactions has drawn increasing research interests in recent years. In this work, we propose a scheme to control the OAM of the third harmonic wave through two cascaded second-order nonlinear processes. A Gaussian beam was frequency doubled at the first stage. Subsequent sum frequency mixing of the Gaussian second harmonic wave and an orthogonal-polarized Laguerre-Gaussian-like fundamental wave generate the third harmonic wave, which carries the same OAM as that of the Laguerre-Gaussian-like fundamental wave. In this experiment, we demonstrated controlling the OAM of the third harmonic wave in a tandem periodically-poled LiTaO3 optical superlattice, and the results are in accordance with theoretical predictions.

The complete mitochondrial genome and phylogenetic analysis of Lepidozona coreanica (Reeve, 1847).

In the present study, the complete mitochondrial genome of Lepidozona coreanica was sequenced and described. The complete mitogenome sequence of L. coreanica is 16,572 bp long and contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes. The base composition was AT biased (70.1%). The 13 PCGs of L. coreanica and the other 15 species of Polyplacophora were used for phylogenetic analysis using maximum-likelihood methods. The results showed that L. coreanica, Ischnochiton hakodadensis, and Chaetopleura apiculata are sister groups of the three lineages.

A further insight into the biosorption mechanism of Au(III) by infrared spectrometry.

BACKGROUND: The interactions of microbes with metal ions form an important basis for our study of biotechnological applications. Despite the recent progress in studying some properties of Au(III) adsorption and reduction by Bacillus megatherium D01 biomass, there is still a need for additional data on the molecular mechanisms of biosorbents responsible for their interactions with Au(III) to have a further insight and to make a better exposition. RESULTS: The biosorption mechanism of Au(III) onto the resting cell of Bacillus megatherium D01 biomass on a molecular level has been further studied here. The infrared (IR) spectroscopy on D01 biomass and that binding Au(III) demonstrates that the molecular recognition of and binding to Au(III) appear to occur mostly with oxygenous- and nitrogenous-active groups of polysaccharides and proteins in cell wall biopolymers, such as hydroxyl of saccharides, carboxylate anion of amino-acid residues (side-chains of polypeptide backbone), peptide bond (amide I and amide II bands), etc.; and that the active groups must serve as nucleation sites for Au(0) nuclei growth. A further investigation on the interactions of each of the soluble hydrolysates of D01, Bacillus licheniformis R08, Lactobacillus sp. strain A09 and waste Saccharomyces cerevisiae biomasses with Au(III) by IR spectrometry clearly reveals an essential biomacromolecule-characteristic that seems the binding of Au(III) to the oxygen of the peptide bond has caused a significant, molecular conformation-rearrangement in polypeptide backbones from ß-pleated sheet to α-helices and/or ß-turns of protein secondary structure; and that this changing appears to be accompanied by the occurrence, in the peptide bond, of much unbound -C=O and H-N- groups, being freed from the inter-molecular hydrogen-bonding of the ß-pleated sheet and carried on the helical forms, as well as by the alternation in side chain steric positions of protein primary structure. This might be reasonably expected to result in higher-affinity interactions of peptide bond and side chains with Au(III). CONCLUSIONS: The evidence suggests that the polypeptides appear to be activated by the intervention of Au(III) via the molecular reconformation and in turn react upon Au(III) actively and exert profound impacts on the course of Au(0) nucleation and crystal growth.

[In situ measurement of the permeability of concrete by FTIR-MIR].

Fourier transform infrared spectroscopy with multiple internal reflection mode (FTIR-MIR) has been applied for the first time to measure the permeability of concrete. The effect of water-cement ratio and curing time on the microstructure and permeability of concrete was studied. Also, the penetration process of H2O and SO4(2-) through the concrete specimens was investigated. The results indicated that the movement of H2O through unsaturated concrete was mainly caused by capillary suction and the movement of SO4(2-) through unsaturated concrete should take into account diffusion, advection caused by a capillary suction flow and the reaction between SO4(2-) and the cement hydration products. The permeability of concrete was determined by its microstructure. With the decrease in water-cement ratio and the increase in curing time, the porosity and the connectivity of pores in concrete decreased, which resulted in the decrease of concrete permeability.

A further insight into the biosorption mechanism of Pt(IV) by infrared spectrometry.

BACKGROUND: Platinum nanomaterial is one of the significant noble metal catalysts, and the interaction of platinum with microbe is one of the key factors in influencing the size and the distribution of the platinum nanoparticles on the microbial biomass. Some properties of Pt(IV) adsorption and reduction by resting cells of Bacillus megatherium D01 biomass have once been investigated, still the mechanism active in the platinum biosorption remains to be seen and requires further elucidating. RESULT: A further insight into the biosorption mechanism of Pt(IV) onto resting cells of Bacillus megatherium D02 biomass on a molecular level has been obtained. The image of scanning electron microscopy (SEM) of the D02 biomass challenged with Pt(IV) displayed a clear distribution of bioreduced platinum particles with sizes of nanometer scale on the biomass. The state of Pt(IV) bioreduced to elemental Pt(0) examined via X-ray photoelectron spectroscopy (XPS) suggested that the biomass reduces the Pt(IV) to Pt(II) followed by a slower reduction to Pt(0). The analysis of glucose content in the hydrolysates of D02 biomass for different time intervals using ultraviolet-visible (UV-vis) spectrophotometry indicated that certain reducing sugars occur in the hydrolyzed biomass and that the hydrolysis of polysaccharides of the biomass is a rapid process. The infrared (IR) spectrometry on D02 biomass and that challenged with Pt(IV), and on glucose and that reacted with Pt(IV) demonstrated that the interaction of the biomass with Pt(IV) seems to be through oxygenous or nitrogenous chemical functional groups on the cell wall biopolymers; that the potential binding sites for Pt species include hydroxyl of saccharides, carboxylate anion and carboxyl of amino acid residues, peptide bond, etc.; and that the free monosaccharic group bearing hemiacetalic hydroxyl from the hydrolyzed biomass behaving as an electron donor, in situ reduces the Pt(IV) to Pt(0). And moreover, the binding of the Pt(IV) to the oxygen of the carbonyl group of peptide bond caused a change in the secondary structure of proteins; i.e. a transformation, in polypeptide chains, of beta-folded to alpha-helical form; it might be expected to be more advantageous than beta-folded form to the platinum nanoparticles under shelter from gathering although the both special conformations of proteins could be much probably responsible for the stabilization of the particles. CONCLUSION: That knowledge could serve as a guide in the researches for improving the preparation of highly dispersive supported platinum catalyst and for fabricating new advanced platinum nanostructured devices by biotechnological methods.

A further insight into the adsorption mechanism of protein on hydroxyapatite by FTIR-ATR spectrometry.

The adsorption mechanism of bovine serum albumin (BSA) on hydroxyapatite (HA) for different time intervals has been studied by Fourier transform infrared (FTIR)-attenuated total internal reflectance (ATR) spectrometry in this paper. The difference spectra obtained in HA and BSA frequency regions demonstrate that the binding of PO, from the phosphate (PO43-) of HA, to the hydrogen of methyl (-CH3), methene (-CH2) and amideII (-CNH) in the protein appears to be much faster and stronger than that of the PO group. In addition, Ca2+ must serve as a key role in the interaction of BSA with HA. The binding of Ca2+ to the oxygen of the peptide bond seems to induce a significant reconformation of polypeptide backbones from ß-pleated sheet to α-helix and ß-turn of helical circles. This alteration seems to have been accompanied by much hydrogen of polypeptides driven to bind PO43- and OH- of the HA actively and much -C=O and HN groups of the peptide bond freed from inter-chain hydrogen bonding to react on Ca2+ and combine strongly with the HA surface. This might be well expected to promote the HA biomineralization.

Spectroscopic characterization of Au3+ biosorption by waste biomass of Saccharomyces cerevisiae.

Some spectroscopic characteristics of Au3+ biosorption by waste biomass of Saccharomyces cerevisiae have been reported in this paper. The effect of temperature on the correlation parameters of chemical kinetics and thermodynamics of the binding reaction was investigated by using AAS. XRD diffraction pattern of gold-loaded biomass revealed that the Au3+ bound on the cell wall of the biomass had been reduced into gold particle. FTIR spectrophotometry on blank and gold-loaded biomass demonstrated that active groups such as the hydroxyl group of saccharides, and the carboxylate anion of amino-acid residues, from the peptidoglycan layer on the cell wall seem to be the sites for the Au3+ binding, and the free aldehyde group of the hemiacetalic hydroxyl group from reducing sugars, i.e. the hydrolysates of the polysaccharides on the peptidoglycan layer, serving as the electron donor, in situ reduced the Au3+ to Au0. XPS and IR characterizations of the interaction between glucose and Au3+ further supported that the reduction of Au3+ to Au0 can directly occur at the aldehyde group of the reducing sugars.

A further insight into the mechanism of Ag+ biosorption by Lactobacillus sp. strain A09.

The mechanism of Ag(+) biosorption by resting cell of Lactobacillus sp. strain A09 has been further investigated at the molecular level using spectroscopic techniques. The values of estimated equilibrium constants, rate constants, half-life periods and apparent enthalpies of the binding reaction were calculated via the determination of Ag(+) adsorbed by the biomass using atomic absorption spectrophotometry (AAS). The reductive ratio of the Ag(+) to Ag(0) by the A09 biomass was examined by X-ray photoelectron spectroscopy (XPS). Analysis for sulfur and nitrogen atomic contents in dry powder of the biomass with EA-1110 elemental analysis (EA) showed that amino acid residues retaining the reductive property of Ag(+) to Ag(0) are very small quantity, whereas glucose content in the hydrolysates of the biomass analyzed by ultraviolet-visible spectrophotometry (UV-vis) indicated that the amount of reducing sugars in the biomass is much larger than 2.71%. The fourier transform infrared (FTIR) spectrophotometry on blank and silver-loaded biomass demonstrated that the chemical functional group such as the free aldehyde group of the hemiacetalic hydroxyl group from reducing sugars, i.e. the hydrolysates of the polysaccharides from the cell wall plays a leading role in serving as the electron donor for reducing the Ag(+) to Ag(0). This result was further supported by characterizations on the interaction of the Ag(+) with glucose using X-ray powder diffractometry (XRD) and FTIR spectroscopy.