Thermodynamic studies of the surface and transport properties in Ag–In and Ag–Sb liquid alloys

The surface tension, surface concentration, viscosity and mutual diffusion co-efficients of the Ag–In and Ag–Sb liquid alloys have been calculated using energetics and derivables from a statistical mechanical framework which recognises the formation of atom clusters of self associates. Our calculations suggest the existence of some form of local order in the systems. Ag–In showed higher tendencies to heterocoordination in the bulk-manifested higher values of mutual diffusion coefficient throughout the concentration range. The viscosity values of Ag–In and Ag–Sb were calculated using the expression reported by Kucharsky which relates the viscosity of a liquid binary alloy to the activity coefficients of the liquid alloy components that are raised to some power m. This exponent m is a fitted parameter. The calculated viscosity values for Ag–Sb had some reasonable agreement with experiment above 0.5 atomic fraction of Sb, using a fitted parameter value of m = 4.5. The fitted parameter value for the viscosity of Ag–In is expected to be in the range 1.5 ≤ m ≤ 3.5.     

Separation and determination of β-casomorphins by using glass microfluidic chip electrophoresis together with laser-induced fluorescence detection

A simple, reliable and reproducible method for the separation and determination of five β-casomorphins (β-CMs, namely TPGN, PGPI, TPGI, TPGP and TPPG) based on glass microfluidic chip electrophoresis and laser-induced fluorescence detection is first described in here. The microfluidic chip electrophoresis and laser-induced fluorescence detection system consisted of a home-made glass "double-T" microchip and a simple LIF detector with excitation and emission wavelengths of 473 and 525 nm, respectively. Fluorescein isothiocyanate (FITC) was used as the precolumn derivatization reagent to label fluorophore on five β-CMs, and the optimum conditions of FITC-derivatization reaction and MCE separation were investigated in detail. Under optimum conditions, five β-CMs were completely separated and detected within 30 min with a detection limit of 18.7-75.1 nmol/L and an RSD (n=5) of 3.0-5.9%, respectively. The proposed method has been successfully used to detect β-CMs in real cheese sample with a recovery of 89-109%, suggesting that our method is sensitive and reliable. These features, as well as its low cost, operation convenience, stability and reusability, make it a promising alternative to β-CMs detection methods.     

Demonstration of α-helical structure of peptides tethered to gold surfaces using surface infrared and circular dichroic spectroscopies

Gold and quartz surfaces terminated in an alkane thiol self-assembled monolayer (SAM) that were partially terminated with azide were reacted with a helical peptide containing two alkyne groups in a Cu(I)-catalyzed Huisgen cycloaddition. Surface grazing incidence angle reflection-absorption infrared spectroscopy (GRAS-IR) was used to determine that when the Au surface was terminated with 25% of the monolayer containing azide groups, 92% of available azide groups reacted with the peptide. The majority of peptides reacted with both alkynes, resulting in peptides tethered to the surface through two covalent bonds. This was confirmed by comparison to a control peptide containing only one reactive alkyne group. Surface circular dichroic (CD) spectroscopy showed that while the helical structure of the peptide was distorted in the reaction solution, α-helical structure was induced when tethered on the SAM functionalized Au surface. Demonstration of the preservation of desired secondary structure of helical elements at a chemically functionalized surface is an important advance in preparing robust biologically mimetic surfaces to integrate functioning proteins into inorganic materials.     

Separation of no-carrier-added 99mTcO4 − from 99Mo–99mTc equilibrium mixture by PEG based aqueous biphasic separation technique using sodium/potassium salts of citric and tartaric acid

Extraction and separation of no-carrier-added (nca) ^99mTcO₄ ^? from ⁹⁹Mo–^99mTc equilibrium mixture was carried out by environmentally benign polyethylene glycol based liquid–liquid aqueous biphasic systems (ABS) consisting various inorganic salts. Among the various inorganic salt trisodium citrate and potassium sodium tartrate showed the suitable salt rich phase for the best separation in this report. The concentration variation of salt rich phase, temperature and PEG phase also exhaustively studied in paper for the achievement of high separation factor. At 40 °C temperature in 50 % (w/v) PEG-4000-2M Na₃citrate showed the highest separation factor (S _Tc/Mo) 1.2 × 10⁷.     

Changes of decay rates of radioactive ~(111)In and ~(32)P induced by mechanic motion

The changes of decay rates of radionuclide 111In(electron capture) and 32P(β decay) induced by exter-nal mechanic motion are studied. The results indicate that,in the external circular rotation in clockwise and anticlockwise centrifuge on Northern Hemisphere(radius 8 cm,2000 r/min) ,the half life of 111In compared with the referred(2.83 d) is decreased at 2.83% and increased at 1.77%,respectively;the half life of 32P compared with the referred(14.29 d) is decreased at 3.78% and increased at 1.75%,respec-tively. When the clockwise and anticlockwise rotations increase to 4000 r/min,the half life of 111In is decreased at 11.31% and increased at 6.36%,respectively;the half life of 32P is decreased at 10.08% and increased at 4.34%,respectively. When the circular rotation is removed,the decay rates of 111In and 32P return back to the referred,respectively. It is found that the external circular rotations in clockwise and anticlockwise centrifuge selectively increased and decreased the decay rates of 111In and 32P,respec-tively,and the effects are strongly dependent on the strength of circular rotation. It is suggested that these effects may be caused by the chiral interaction.     

Samarium diiodide induced asymmetric synthesis of γ-butyrolactone using chiral auxiliaries derived from isosorbide and isomannide

The asymmetric reductive coupling reaction of various acrylates derived from D-isosorbide and D-isomannide with acetophenone mediated by samarium diiodide to give both enan-tiomers of the optically active γ-butyrolactone was described.The best enantiomeric excess of the products was 60%.     

In situ FTIR study of surface site transformations in Pd3In/α-Al2O3 and Pd3Ag/α-Al2O3 induced by CO adsorption

In the course of the treatment of Pd3Ag/α-Al2O3 in 0.5%CO + He at 200 °C, intense transformation of single atom Pd1 surface sites isolated from each other by Ag atoms to multiatomic Pdn (n ≥ 2) ensembles occurs, as revealed by a rapid increase in the intensity of multibonded CO bands in FTIR spectra. The structure of intermetallic Pd3In nanoparticles is significantly more stable, and the formation of new multiatomic adsorption centers was not observed even after extended CO exposures.     

Separation and identification of trinucleotide–melphalan adducts from enzymatically digested DNA using HPLC–ESI–MS

Melphalan is a bifunctional alkylating agent that covalently binds to the nucleophilic sites present in DNA. In this study we investigated oligonucleotides prepared enzymatically from DNA modified with melphalan. Calf thymus DNA was incubated in-vitro with melphalan and the resulting modifications were enzymatically cleaved by means of benzonase and nuclease S1. Efficient sample preconcentration was achieved by solid-phase extraction, in which phenyl phase cartridges resulted in better recovery of the modified species than C₁₈. The applied enzymatic digestion time resulted in production of trinucleotide adducts which were efficiently separated and detected by use of reversed-phase HPLC coupled to an ion-trap mass spectrometer with electrospray ionization. It was assumed that melphalan could act as both a monofunctional and bifunctional alkylating agent. Mono-alkylated adducts were much more abundant, however, and the alkylation site was located on the nucleobases. On the other hand, we unequivocally identified cross-link formation in DNA, even though at low abundance and only a few adduct types were detected. Figure Different Alkylation reactions of Melphalan with DNA     

Practical synthesis of N-Boc- and N-Cbz-α-amido stannanes from α-amido sulfones using TMSSnBu3 and CsF

In the presence of TMSSnBu(3) and CsF, stannylation of N-Boc- and N-Cbz-α-amido sulfones proceeded very well to afford the corresponding α-amido stannanes in moderate-to-high yields. This reaction tolerated α-aryl-, alkenyl-, and alkyl-substituted α-amido sulfones as well as substrates containing either an ester or cyano moiety, which might be reactive with lithium or magnesium stannides employed in conventional stannylation.     

Synthesis of gold nanoparticles on the surface of pyrolytic graphite using penicillin as a stabilizing reagent and the catalytic oxidation of α-naphthylamine

Electrochemical synthesis of gold nanoparticles on the surface of pyrolytic graphite using penicillin as a stabilizing reagent was proposed. The gold nanoparticles were characterized by scanning electron microscopy, cyclic voltammetry, IR spectra, UV spectra, and powder X-ray diffraction spectra. The electro-chemical catalysis of penicillin for α-naphthylamine was demonstrated.     

In situ 19F NMR spectroscopy study of enzymatic transglycosylation reactions using α-d-aldohexopyranosyl fluorides as donors and acceptors

The use of ¹⁹F NMR spectroscopy to study the kinetics of the self-condensation reaction of α-d-aldohexopyranosyl fluorides catalysed by α-glycosidases is described. The corresponding fluorinated disaccharides thus synthesised present separate individual fluorine resonances allowing the integration of each species. This method looks particularly useful to help in the choice of donor in enzymatic transglycosylation reactions since the self-condensation reaction always remains in competition with the condensation reaction (reaction of the donor with acceptors other than itself).     

Characterization of prehistorical glass beads excavated from Khao Sam Kaeo (Chumphon, Thailand) using PIXE and SEM–EDS

It was proved that non-destructive and non-sampling methods were used to analyze the composition of the archaeological glasses. Glass has been used in ornaments and decoration in Thailand for thousands of years. In this study, glass bead fragments found from the archaeological site at Khao Sam Kaeo, Chumphon Province, southern Thailand were analyzed by the proton induced X-ray emission spectroscopy (PIXE) and scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy (SEM?CEDS). The composition analysis showed that copper was mainly presence as the colorant. Titanium, common impurity in sand, was all present in the glass bead samples. Furthermore, this type of glass almost spread over the various sites in this region that demonstrated the long distance or exchange connections. Finally, PIXE and SEM?CEDS have been used to be the efficient techniques to analyze the archaeological objects, especially the glassy materials, to understand their characteristics and how they were produced in ancient times.     

Rapid screening and identification of α-glucosidase inhibitors from mulberry leaves using enzyme-immobilized magnetic beads coupled with HPLC/MS and NMR

α-Glucosidase plays important roles in the digestion and absorption of carbohydrates in the small intestine. The inhibition of α-glucosidase is regarded as a potential way to treat diabetes. We established an approach to screening α-glucosidase inhibitors from medicinal plants using enzyme-coated magnetic bead. Using 1-(3-dimethyl-aminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide as reaction reagents, α-glucosidase was immobilized on the magnetic beads by covalent linkage. The conjugation of α-glucosidase to the magnetic beads was characterized using scanning electron microscope and X-ray diffractometer. The proposed approach was applied in fishing potential α-glucosidase inhibitors from extract of Morus alba, a Chinese medicinal plant. The structures of potential active compounds were identified via liquid chromatography-mass spectrometry and nuclear magnetic resonance. The results demonstrated that two flavonoids (isoquercitrin and astragalin) could bind to α-glucosidase, which was confirmed via conventional α-glucosidase inhibitory assay. Our findings suggested that enzyme-coated magnetic beads may be suitable for discovering active compounds from medicinal plants.     

In vivo detection of DNA adducts induced by cisplatin using capillary HPLC–ICP-MS and their correlation with genotoxic damage in Drosophila melanogaster

The antitumoral effect of cisplatin [cis-diamminodichloroplatinum(II)] in mammals is related to its binding to DNA components. However, there is a lack of specific chemical methods to selectively detect those adducts formed in vivo at low concentrations. In this work, a new sensitive and selective method of determining cisplatin–DNA adducts based on the use of element-selective mass spectrometry is proposed, and the method is then applied to detect cisplatin adducts induced in vivo in somatic cells of Drosophila melanogaster. The bioanalytical strategy proposed here allows the determination of the most important DNA adduct formed between adjacent guanine units of the same DNA strand with cisplatin, and it is based on the coupling of capillary liquid chromatography (cap-LC) to inductively coupled plasma mass spectrometry (ICP-MS). This set-up allows the simultaneous monitoring of the Pt (from the drug) and P (from the DNA components) present in these adducts, once they have been cleaved by enzymatic hydrolysis of the DNA samples. Using this instrumental set-up, the adducts of cisplatin formed in vivo when D. melanogaster flies are exposed to different cisplatin concentrations can be detected and their concentration determined. The results obtained show a direct correlation between the concentration of cisplatin adducts, the induced genotoxic damage (measured as DNA strand breaks using the Comet assay) and the cisplatin concentration. Figure The work illustrates the complementary use of bioanalytical and biological information to study cisplatin interactions with DNA is vivo at biologically relevant concentrations of the drug     

Separation and purification of 90Sr from PUREX HLLW using N,N,N′,N′-tetra(2-ethylhexyl) diglycolamide

This paper describes a method for the separation and purification of ⁹⁰Sr from PUREX–HLLW employing solvent extraction and precipitation techniques. 30 % TBP in n-dodecane was used for the removal of residual uranium, plutonium and neptunium from HLLW. Trivalent actinides and lanthanides were subsequently removed using N,N,N’,N’-tetra(2-ethylhexyl) diglycolamide (TEHDGA, 0.20 M in 30 % isodecyl alcohol and n-dodecane). ⁹⁰Sr was selectively extracted from actinides and lanthanides depleted HLLW using 0.3 M TEHDGA in 5 % isodecyl alcohol and dodecane. Loaded strontium was stripped using 0.01 M HNO₃ and further purified by radiochemical precipitation technique after adding Fe and natural strontium as carriers. Based on the experimental results, a flow-sheet was formulated and mCi levels of ⁹⁰Sr recovered.     

Experimental measurements and theoretical calculations for proton,deuteron and α-particle induced nuclear reactions on calcium: special relevance to the production of <Superscript>43,44</Superscript>Sc

The cross sections of the proton, deuteron and α-particle induced nuclear reactions on Ca were determined experimentally up to 20 MeV. The obtained experimental data were validated theoretically using EMPIRE-3.2 and TALYS-1.6. The production yields of ⁴³Sc and ^44m,gSc radioisotopes were calculated and discussed in view of the reported experimental data. Of all the production routes, the ⁴⁴Ca(p,n)^44m,gSc and ⁴³Ca(d,n)^44m,gSc showed highest yields of 1206 MBq/µA.h (15 → 5 MeV) and 204 MBq/µA.h (8 → 0 MeV), respectively. The α-particles induced reactions on ^natCa or ⁴⁰Ca were found to be suitable for producing considerable activity of ⁴³Sc at energy range 8–20 MeV.     

Stereoselective synthesis of cyclic hemiacetals from 4-formylbenzoates and α,β-unsaturated aldehydes using a sulfoalkyl-substituted N-heterocyclic carbene catalyst

N-Heterocyclic carbene-catalyzed transformation of 4-formylbenzoates and α,β-unsaturated aldehydes to cyclic hemiacetals is described. The reaction proceeded smoothly when the sulfopropyl-substituted imidazolium salt was used as the catalyst. Various substrates were converted to the corresponding cyclic hemiacetals in a stereoselective manner.     

Reactive organoallyl species generated from aryl halides and allene: allylation of α,β-unsaturated aldehydes and cyclic ketones employing Pd/In transmetallation processes

Allylation of α,β-unsaturated aldehydes and cyclic ketones promoted by Pd/In transmetallation processes has been studied. The unsaturated aldehydes underwent regioselective 1,2-addition to afford secondary homoally alcohols. The reactions have been performed using Pd(OAc)₂/PPh₃ as catalytic system and metallic indium affording the products in good yields. The same transformation with unsaturated ketones proved to be less efficient, while saturated cyclic ketones delivered generally excellent yields in the presence of CuI. In these latter processes the presence of a distal heteroatom influences the reaction rate.     

Electrical double layer in surface-inactive electrolyte solution and adsorption of halide ions from 0.1 M solutions on liquid Cd–Ga and In–Ga alloys in gamma-butyrolactone

The double-layer characteristics of liquid renewable Cd–Ga (0.3 at % Cd) and In–Ga (14.2 at % In) electrodes in the gamma-butyrolactone (GBL) solutions of various electrolytes are studied by measuring the differential capacitance and using the method of open-circuit jet electrode. For the (Cd–Ga)/GBL and (In–Ga)/GBL interfaces, the zero-charge potentials, which are not distorted by the specific adsorption of ions, and the chemisorption potential drops of solvent are determined. It is shown that, in spite of the fact that the work function decreases as we pass from (In–Ga) to (Cd–Ga), the chemisorption potential drops of solvent on both electrodes are close. This behavior is explained by a closer approach of GBL dipoles to the surface of (Cd-Ga) electrode providing more effective overlapping of donor–acceptor levels of metal and solvent. It is shown that, in GBL, the adsorption parameters of halide ions and their surface activity series depend on the metal nature. On the (Cd–Ga) and (In–Ga) electrodes, the reversed surface activity series of halide ions is observed: on the Hg electrode in various solvents, the surface activity increases in the series Cl^– < Br^– < I^–, whereas on the (Cd–Ga) and (In–Ga) electrodes in GBL, it varies in the reverse series I^– < Br^– < Cl^–.