Chemical Engineering @ChemengFiles.Com

LEO Pharma is progressing by leaps and bounds in the Chinese market by creating a subsidiary with the ambition of becoming the leading dermatological China.

The new company, LEO Pharma China, will market the broad portfolio of LEO Pharma of drugs protected by patents and high level for the treatment of chronic skin psoriasis and other dermatological products (pharmaceuticals for the treatment of skin diseases).

The leading brand for psoriasis LEO Pharma, Daivobet ®, has just been adopted by the Chinese authorities and can now be marketed in China.

LEO Pharma is progressing by leaps and bounds in the Chinese market by creating a subsidiary with the ambition of becoming the leading dermatological China.

The new company, LEO Pharma China, will market the broad portfolio of LEO Pharma of drugs protected by patents and high level for the treatment of chronic skin psoriasis and other dermatological products (pharmaceuticals for the treatment of skin diseases).

The leading brand for psoriasis LEO Pharma, Daivobet ®, has just been adopted by the Chinese authorities and can now be marketed in China.

The effect of bacterial surface biopolymers on bacterial adhesion to surfaces was studied through experiments and modeling. Atomic Force Microscopy (AFM) provided the tool to measure the interaction forces between different bacterial cells and silicon nitride tips under different chemical conditions at a nanoscopic level. Two bacterial strains were considered: Pseudomonas putida KT2442 and Escherichia coli K-12 JM109. This study addressed the following issues: 1) the effect of solution ionic strength and solvent polarity on adhesion between Pseudomonas putida KT2442 and the silicon nitride AFM tip, 2) role of heterogeneity of bacterial surface biopolymers on bacterial adhesion, 3) role of lipopolysaccharides (LPS) on adhesion at three different scales: continuous, batch, and nanoscale, and 4) nature of interactions between E. coli JM109 and a model surface (silicon nitride tip).

The effect of bacterial surface biopolymers on bacterial adhesion to surfaces was studied through experiments and modeling. Atomic Force Microscopy (AFM) provided the tool to measure the interaction forces between different bacterial cells and silicon nitride tips under different chemical conditions at a nanoscopic level. Two bacterial strains were considered: Pseudomonas putida KT2442 and Escherichia coli K-12 JM109. This study addressed the following issues: 1) the effect of solution ionic strength and solvent polarity on adhesion between Pseudomonas putida KT2442 and the silicon nitride AFM tip, 2) role of heterogeneity of bacterial surface biopolymers on bacterial adhesion, 3) role of lipopolysaccharides (LPS) on adhesion at three different scales: continuous, batch, and nanoscale, and 4) nature of interactions between E. coli JM109 and a model surface (silicon nitride tip).

Hot-wire chemical vapor deposition is a promising technique for deposition of thin amorphous, polycrystalline, and epitaxial silicon films for photovoltaic applications. Fundamental questions remain, however, about the gas-phase and surface-kinetic processes involved. To this end, the nature of the wire decomposition process has been studied in detail by use of mass spectrometry. Atomic silicon was the predominant radical formed for wire temperatures above 1500 K, and catalysis was evident for SiH3 production with the use of a new wire. Aged wires appear to produce radicals by a non-catalyzed route and chemical analysis of these wires reveal large quantities of silicon at the surface, consistent with the presence of a silicide layer. This study is the first of its kind to correlate radical desorption kinetics with filament aging for the hot-wire chemical vapor deposition technique.

Threshold ionization mass spectrometry revealed large quantities of the SiH2 radical, attributed to heterogeneous pyrolysis on the walls of the reactor. At dilute (1%) silane pressures of up to 2 Torr, a negligible amount of ions and silicon agglomerates (Si2, Si2H, Si2H6) were detected. Density functional theory calculations reveal an energetically favorable route for the reaction of Si and SiH4, producing Si2H2 and H2. The trace amounts of Si2H2 observed experimentally, however, may suggest that an intermediate spin state transition involved in this reaction is slow under the hot-wire conditions used. Monte Carlo simulations of the hot-wire reactor suggest SiH3 is the predominant growth species under conditions leading to amorphous and polycrystalline growth. The flux of atomic hydrogen, rather than the identity of the precursor, appears to be the more important factor in governing the amorphous-to-microcrystalline transition that occurs upon hydrogen-dilution. Two-dimensional Monte Carlo simulations were used to model a hot-wire reactor for the first time, showing that filament arrays can be used to improve film growth uniformity. Under conditions where agglomerate formation does not occur, continuum simulations predict a maximum growth rate of 10 nm/s for dilute (1%) silane conditions and a rate of 50 nm/s for pure silane.

Hot-wire chemical vapor deposition is a promising technique for deposition of thin amorphous, polycrystalline, and epitaxial silicon films for photovoltaic applications. Fundamental questions remain, however, about the gas-phase and surface-kinetic processes involved. To this end, the nature of the wire decomposition process has been studied in detail by use of mass spectrometry. Atomic silicon was the predominant radical formed for wire temperatures above 1500 K, and catalysis was evident for SiH3 production with the use of a new wire. Aged wires appear to produce radicals by a non-catalyzed route and chemical analysis of these wires reveal large quantities of silicon at the surface, consistent with the presence of a silicide layer. This study is the first of its kind to correlate radical desorption kinetics with filament aging for the hot-wire chemical vapor deposition technique.

Threshold ionization mass spectrometry revealed large quantities of the SiH2 radical, attributed to heterogeneous pyrolysis on the walls of the reactor. At dilute (1%) silane pressures of up to 2 Torr, a negligible amount of ions and silicon agglomerates (Si2, Si2H, Si2H6) were detected. Density functional theory calculations reveal an energetically favorable route for the reaction of Si and SiH4, producing Si2H2 and H2. The trace amounts of Si2H2 observed experimentally, however, may suggest that an intermediate spin state transition involved in this reaction is slow under the hot-wire conditions used. Monte Carlo simulations of the hot-wire reactor suggest SiH3 is the predominant growth species under conditions leading to amorphous and polycrystalline growth. The flux of atomic hydrogen, rather than the identity of the precursor, appears to be the more important factor in governing the amorphous-to-microcrystalline transition that occurs upon hydrogen-dilution. Two-dimensional Monte Carlo simulations were used to model a hot-wire reactor for the first time, showing that filament arrays can be used to improve film growth uniformity. Under conditions where agglomerate formation does not occur, continuum simulations predict a maximum growth rate of 10 nm/s for dilute (1%) silane conditions and a rate of 50 nm/s for pure silane.