Indication of the presence of acceptor states around the Fermi level of amorphous silicon

A junction was grown by sputtering of silicon on a single crystal of high resistivity n-type silicon. The reverese bias V-I characteristics followed Fowler-Nerdheim model with a sudden change in the slope at 0.4 volt indicating an increase in the barrier height. This is attributed to tunneling of extra electrons from the bottom of the conduction band of the substrate to the acceptor traps that face each ether at this bias.     

Synthesis of a peptide nucleic acid with a novel 1‐methyl‐6‐mercaptopurine base

A novel peptide nucleic acid (PNA) monomer 16 containing a novel 1‐methyl‐6‐mercaptopurine base was synthesized by coupling the in situ generated acid chloride of (1‐methyl‐6‐mercaptopurin‐9‐yl)acetic acid ( 6 ) into an L‐lysine backbone ( 13 ) using 10% CCl₄ in pyridine and Ph₃P. Compound 6 was synthesized from 6‐mercapto‐1‐methylpurine and ethylbromoacetate in the presence of NaH followed by alkaline hydrolysis and subsequent neutralization with a cation exchange resin. The L‐lysine backbone ( 13 ) was obtained by the reaction of N?‐CBZ‐L‐lysine allyl ester with Boc‐aminoactaldehyde in the presence of NaBH₃CN under reductive amination conditions. Oligomerization of the monomer 16 to PNA analogues was achieved using BOC‐BHA‐PEG‐PS resin as a solid support and the in situ generated acid chloride of 16 by 10% CCl₄ in DCM in the presence of Ph₃P.     

Some uses of transition metal complexes as anti-cancer and anti-HIV agents

The success of the clinical uses of cisplatin, cis-[Pt(II)(NH(3))(2)Cl(2)], has stimulated considerable interest in using other metal complexes as new therapeutic agents. This perspective describes our recent work on several classes of gold(III), platinum(II), ruthenium(II, III, IV), iron(II) and vanadium(IV) complexes for anti-cancer and anti-HIV treatments.     

Cyclometalated Platinum(II) Complexes as Highly Sensitive Luminescent Switch‐On Probes for Practical Application in Protein Staining and Cell Imaging

Protein‐staining platinum : The luminescent switch‐on characteristic of the platinum(II) complex can be utilized for staining a series of proteins in sodium dodecyl sulfate‐polyarcylamide gels, to give emissive gel images directly under UV light (see figure). The detection sensitivity for BSA protein is down to 6.0 ng, revealing potential practical applications of luminescent platinum(II) complexes in the luminescent signaling of biomolecules.

     

Microwave and Ionic Liquids: Inverse Temperature Dependence of Viscosity in Aqueous Medium of Grafted Copolymers

We elaborated a route to the thermosensitive polyelectrolyte system composed of 1‐methyl‐3‐vinylimidazolium salt with β‐cyclodextrin complexed counterions and mono‐(meth)acrylic functionalized poly(N‐isopropylacrylamide) as grafted side chains via a three‐step synthetic procedure. The aqueous solution of the polyelectrolyte displays partially inverse thermoresponsive behavior; it exhibits enhancement of shear viscosity up to body temperature. Furthermore, based on classically prepared poly(NIPAAm) bearing terminal amino groups, corresponding (meth‐) acrylamide‐type of macromonomers were easily obtained under microwave conditions.

     

Characterizations of self-combustion reactions (SCR) for the production of nanomaterials used as advanced cathodes in Li-ion batteries

In this work, self-combustion reactions (SCR) for the preparation of important cathode materials for rechargeable Li-ion batteries were investigated by thermal analytical tools (DSC, ARC, TGA), electron microscopy, XRD, various spectroscopies (MS, Raman, FTIR) and elemental analysis by ICP. The systems studied include solutions containing metal nitrates at the right stoichiometry and sucrose as a fuel, for the preparation of LiMn_0.5Ni_0.5O₂ (layered), LiMn_1.5Ni_0.5O₄ (spinel), LiMn_0.33Ni_0.33Co_0.33O₂ (layered), and LiMn_0.4Ni_0.4Co_0.2O₂ (layered). Similar products, which do not depend on the atmosphere of the processes (air or inert) were obtained by spontaneous SCR and the gradual heating of the same solutions by DSC, ARC, and TGA. The reactions involve the partial caramelization of sucrose, complicated by red-ox reactions with the nitrates that form solid products, whose organic part is finally decomposed around 400 °C. The presence of cobalt ions has a stabilizing effect, which is expressed by the low dissolution rates of Li ions from the solid products thus formed, into aqueous solutions. The reaction mechanisms are discussed herein.     

Development of Functional Composite Cu(II)-Polyoxometalate/PLA with Antimicrobial Properties

Novel composite self-disinfecting films of polylactic acid (PLA) filled with nanosized particles of double sodium–copper(II) paratungstate B Na₂Cu₃(CuOH)₂[W₁₂O₄₀(OH)₂]·32H₂O (POM) were developed. The solvent casting (POM/PLA film) and solvent-free melt extrusion methods (Extr. POM/PLA film) were applied for film preparation. The copper (II) ion release to water from both types of the films after 10 days at different temperatures demonstrated that the PLA matrix acts as a diffusion barrier, and the resulting concentration of released copper in water at room temperature remained low, at 0.79% for POM/PLA film and 0.51% for Extr. POM/PLA film. The POM-containing films reveals a significant inhibitory effect against E. coli ATCC 25922 in the agar diffusion test. The numbers of CFUs in washes of the films after incubation for 24 h were found to be 3.6 log CFU mL^–1 (POM/PLA film) and 4.1 log CFU mL^–1 (Extr. POM/PLA film). The films combine the antibacterial properties of POM and a bio-based polymer matrix, which makes them a prospective coating material for applications in hospital indoor environments. Excellent thermal stability of POM gives a technological advantage for industrial manufacturing to allow the processing of novel composite material in the solvent free (molten) state.     

Aggregation and Adsorption Properties of Tetramethylsulfonatoresorcinarenes and their Associates with Nonionogenic Guest Molecules in Aqueous Solutions

Present paper reports on tensiometric studies of tetramethylsulfonatoresorcinarenes 1 and 2 with nonionogenic guests 3 and 4, pyrimidin derivative and O,O-dymethyl-1,1-dimethyl-3-oxobutylphosphonate, respectively. Association of resorcinarenes with these guests leads to dramatic change of adsorption characteristics of their solutions. CCMs₁ of associates (1&3, 1&4, 2&3, and 2&4) are lower and the estimated surface activity, as well as the height of adsorption layers are higher than for individual substances. Aggregation of compounds 1–4 and association of 1 with 3 and 4 in solution were confirmed by ¹H NMR spectra and studied by diffusion NMR with impulse magnetic field gradient.     

The Complexation Properties of the Water-Soluble Tetrasulfonatomethylcalix[4]resorcinarene toward α-Aminoacids

The flexible bowl-type water-soluble molecule1, consisting of a resorcinol core and fourconvergent tetrasulfonatomethylene groups, existingas a tetraanion in neutral water solution, was studiedas the host molecule for recognition of-aminoacids. Out of 12 examined guestmolecules only those possessing aromatic hydrophobicmoieties or a long hydrophobic chain with a second ionogenic groupform inclusion complexes with 1. The complex formationwas considered with the help of both ¹H NMRand pH-metric titration in a broad range of pH.The role of host and guest geometric complementarity aswell as additional – and hydrophobic interactionsis discussed. The lack of these interactions inaqueous media provides domination of the guestsolvation by water over the 1 : 1 complexformation with 1.