Formation and structure of graphene waves on Fe(110).

A very rich Fe-C phase diagram makes the formation of graphene on iron surfaces a challenging task. Here we demonstrate that the growth of graphene on epitaxial iron films can be realized by chemical vapor deposition at relatively low temperatures, and that the formation of carbides can be avoided in excess of the carbon-containing precursors. The resulting graphene monolayer creates a novel periodically corrugated pattern on Fe(110). Using low-energy electron microscopy and scanning tunneling microscopy, we show that it is modulated in one dimension forming long waves with a period of ∼4 nm parallel to the [001] direction of the substrate, with an additional height modulation along the wave crests. The observed topography of the graphene/Fe superstructure is well reproduced by density functional theory calculations, and found to result from a unique combination of the lattice mismatch and strong interfacial interaction, as probed by core-level photoemission and x-ray absorption spectroscopy.

Controllable p-doping of graphene on Ir(111) by chlorination with FeCl3.

The in situ chlorination of graphene on Ir(111) has been achieved by depositing FeCl(3) followed by its thermal decomposition on the surface into FeCl(2) and Cl. This process is accompanied by an intercalation of Cl under graphene and formation of an epitaxial FeCl(2) film on top, which can be removed upon further annealing. A pronounced hole doping of graphene has been observed as a consequence of the annealing-assisted intercalation of Cl. This effect has been studied by a combination of core-level and angle-resolved photoelectron spectroscopies (CL PES and ARPES, respectively), near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and low-energy electron diffraction (LEED). The ease of preparation, the remarkable reproducibility of the doping level and the reversibility of the doping upon annealing are the key factors making chlorination with FeCl(3) a promising route for tuning the electronic properties in graphene.

Growth and ordering of Ni(II) diphenylporphyrin monolayers on Ag(111) and Ag/Si(111) studied by STM and LEED.

The room temperature self-assembly and ordering of (5,15-diphenylporphyrinato)nickel(II) (NiDPP) on the Ag(111) and Ag/Si(111)-(√3 × âˆš3)R30° surfaces have been investigated using scanning tunnelling microscopy and low-energy electron diffraction. The self-assembled structures and lattice parameters of the NiDPP monolayer are shown to be extremely dependent on the reactivity of the substrate, and probable molecular binding sites are proposed. The NiDPP overlayer on Ag(111) grows from the substrate step edges, which results in a single-domain structure. This close-packed structure has an oblique unit cell and consists of molecular rows. The molecules in adjacent rows are rotated by approximately 17° with respect to each other. In turn, the NiDPP molecules form three equivalent domains on the Ag/Si(111)-(√3 × âˆš3)R30° surface, which follow the three-fold symmetry of the substrate. The molecules adopt one of three equivalent orientations on the surface, acting as nucleation sites for these domains, due to the stronger molecule-substrate interaction compared to the case of the Ag(111). The results are explained in terms of the substrate reactivity and the lattice mismatch between the substrate and the molecular overlayer.

One-dimensional corrugation of the h-BN monolayer on Fe(110).

We report on a new nanopatterned structure represented by a single atomic layer of hexagonal boron nitride (h-BN) forming long periodic waves on the Fe(110) surface. The growth process and the structure of this system are characterized by X-ray absorption (XAS), core-level photoemission spectroscopy (CL PES), low-energy electron microscopy (LEEM), microbeam low-energy electron diffraction (µLEED), and scanning tunneling microscopy (STM). The h-BN monolayer on Fe(110) is periodically corrugated in a wavy fashion with an astonishing degree of long-range order, periodicity of 2.6 nm, and the corrugation amplitude of ∼0.8 Å. The wavy pattern results from a strong chemical bonding between h-BN and Fe in combination with a lattice mismatch in either [111] or [111] direction of the Fe(110) surface. Two primary orientations of h-BN on Fe(110) can be observed corresponding to the possible directions of lattice match between h-BN and Fe(110), with approximately equal area of the boron nitride domains of each orientation.

Impact of oxygen coadsorption on intercalation of cobalt under the h-BN nanomesh.

The process of penetration of cobalt atoms through the h-BN nanomesh on Rh(111) is investigated with both spectroscopic and microscopic techniques. It is discovered that oxygen coadsorption can drastically modify the physical properties and behavior of the deposited Co clusters upon postannealing. In the absence of oxygen, Co forms small nanoparticles in the pores (bonding parts) of the h-BN nanomesh, which start to agglomerate at elevated temperatures without any considerable intercalation. However, even a tiny amount of coadsorbed oxygen reduces cobalt agglomeration and greatly promotes its intercalation and trapping under h-BN. The oxygen exposure necessary for a complete intercalation of 1-2 monolayers of Co is very low, and the formation of oxidic species can be easily avoided. The nanomesh structure remains intact upon intercalating submonolayer amounts of Co, while further intercalation gradually distorts and finally destroys the periodic corrugation. Fortunately, this process is not accompanied by damaging the h-BN sheet itself, and the original structure can be restored by removing Co upon annealing at higher temperatures.

An x-ray absorption and photoemission study of the electronic structure of Ni porphyrins and Ni N-confused porphyrin.

Investigations of chemical bonding and electronic structure features for polycrystalline (porphyrinato)nickel (II) (NiP, the simplest Ni porphyrin), (5,10,15,20-tetraphenylporphyrinato)nickel (II) (NiTPP) and (2-aza-21-carba-5,10,15,20-tetraphenylporphyrinato)nickel (II) (N-confused NiTPP, NiNCTPP) have been performed by means of high-resolution soft x-ray absorption and x-ray photoemission spectroscopy. The Ni 2p(3/2) x-ray absorption spectra show strong π-back-bonding in these compounds leading to a high-energy shift (1.2 eV for the NiP and NiTPP) of the entire absorption structure compared to Ni metal. It has been found that the main absorption line of the Ni 2p(3/2) spectrum of the NiNCTPP is shifted by an additional 0.5 eV to higher energies in comparison with those for other nickel porphyrins. This shift is evidence of stronger back-donation (metal-to-ligand charge transfer) and a smaller effective number of 3d electrons on the central Ni atom in the NiNCTPP as compared to other Ni porphyrins. The confused N atom in the NiNCTPP is of pyrrolic type (protonated nitrogen), which was confirmed by the N 1s absorption and core-level photoemission spectra.

[Synthesis of nitric oxide in patients with viral hepatitis]. / Sintez okisi azota v organizme bol'nykh virusnymi gepatitami.

The end products of nitric oxide (NO) metabolism in human organism, i.e. anions, nitrites (NO2) and nitrates (NO3), are excreted predominantly (95%) via urine. The quantity of these products in urine is an adequate index of NO synthesis in human organism. We measured the quantities of of NO2 and NO3 excreted during of monoviral hepatitis A, B, C, D and in the course of mixed viral hepatic infections, which were caused by the above mentioned viruses. The hyperexcretion of NO2 and NO3 was higher and longer during hepatitis C and D versus hepatitis B, and during the latter versus hepatitis A. The inability of NO to stop the infection may be caused by low sensitivity of the viruses to NO and/or by local low concentration of NO in the site of inflammation.

[Changes in synthesis of nitric oxide, blood levels of ACTH and cortisol in viral hepatitis B]. / Izmenenie sinteza oksida azota, soderzhaniia adrenokortikotropnogo gormona i kortizola v krovi pri virusnom gepatite B.

We examined 170 patients with acute viral hepatitis B (AVH-B) and 10 patients with chronic hepatitis B (CH-B) exacerbation. 85% of them were under 40 years old. During the 12-hour night period we measured urine excretion of nitrites (NO2-) and nitrates (NO3-). It was significantly high in AVH-B but in CH-B exacerbation it did not differ from the controls. ACTH and hydrocortisone blood levels were significantly high in AVH-B and in CH-B exacerbation. Though hydrocortisonemia and nitrituria/nitraturia during AVH-B were both high, the correlation between them was negative due to nitric oxide (NO) synthesis suppression by hydrocortisone. A negative correlation between nitrituria/nitraturia and ALAT, ASAT, bilirubin, alkaline phosphatase, gamma-glutamyl-transpeptidase is an indirect evidence for a protective role of NO against viral hepatitis B.

[Role of bacterial protease degrading secretory immunoglobulin A in Klebsiella persistence]. / Rol' bakterial'noi proteazy, degradiruiushchei sekretornyi immunoglobulin A, v persistentsii klebsiell.

During the study of 186 K. pneumoniae clinical strains the presence of SIgA-protease activity was detected in 109 isolates (58.6%). The PCR test system permitting the detection of iga gene DNA in K. pneumoniae strains isolated in purulent inflammatory processes of different localization was developed. For the first time a conjugative plasmid with a mol. wt. of 100 MD was detected in K. pneumoniae clinical isolates. This plasmid controlled the capacity of inactivating SIgA, carried the markers of antibiotic resistance and was capable of expression in a wide circle of hosts belonging to the family Enterobacteriaceae. The results of in vitro experiments revealed that the strains containing plasmid SIgA were cytotoxic with respect to cells HEp-2 and more resistant to the digestive action of enzymes produced by the phagolysosomes of guinea pig peritoneal cells. As shown on the in vivo biological model with the use of the genetically linked pair of Salmonella typhimurium 274 vaccine strains, differing in SIgA-protease activity, plasmid pSigA ensured more prolonged survival of bacteria in mice in comparison with the nonplasmid variant. The study of SIgA-protease activity of K. pneumoniae strains circulating among patients with a view to the detection of clones causing the development of persistent infection was shown to have good prospects.

[The antimicrobial activity of nitric oxide and its role in the infectious process]. / Antimikrobnaia aktivnost' okisi azota i ee rol' v infektsionnom protsesse.

In this article information on an important role of nitric oxide (NO) in inhibiting the growth of a number of pathogenic microorganisms, including intracellular parasites, and their elimination from the host body is presented. Differences between the mechanisms of the production of NO and free-radical compounds having antimicrobial action are given. The regulation of the activity of constitutive NO-synthase and inducible NO-synthase and the relationship between the latter and the phagocytic activity and production of anti-inflammatory cytokines are described. An important role of NO in the development of the nonspecific resistance of the body is mentioned.

[Effectiveness of cefotetan in clinical practice]. / Effektivnost' tsefotetana v klinicheskoi praktike.

Forty five patients at the age of 15 to 84 years with signs of infection requiring active antibacterial therapy were treated with cefotetan. In the majority of the patients pulmonary affections such as double pneumonia, pleurisy or bronchopneumonia were stated. In some patients bronchopulmonary pathological processes were associated with pancreatitis, cholecystitis or other diseases of the gastrointestinal tract. A separate group included patients with diseases of the small pelvis organs (pelvioperitonitis, metroendometritis or prostatitis) and diseases of the urogenital system (pyelonephritis) arachnoiditis. In all the patients except for one with bronchopneumonia at the background of chronic myeloleukemia and agranulocytosis the results of the treatment were good and satisfactory. Cefotetan proved to be efficient in the treatment of purulent affections of the skin and subcutaneous fat (abscesses and phlegmona), trophic disturbances at the background of pathological processes in the vessels and pyoseptic condition. Cefotetan practically had no side effects. Only in 2 patients insignificant nausea during the first 2 days of the treatment was recorded. In some patients the antibiotic intramuscular injections were painful with formation of cold infiltrates. After intravenous administration of cefotetan no adverse reactions were observed.