Controlling plasma composition during carbon film deposition in microwave discharges by means of optical-emission spectroscopy

Optical emission spectra from the microwave discharge plasma that is used to activate gas-phase deposition of carbon films are systematically investigated under various deposition conditions. The line emission intensities from CH and C₂ radicals, which are responsible for the growth of the diamond and graphite phases, respectively, are studied as functions of the main macroparameters of the process. To find the relation between the features of the emission spectra and the composition of the films obtained, the films were examined using Raman spectroscopy and electron microscopy. It is shown that monitoring the relative intensities of the spectral lines can be used to obtain the desired type of film, in which case the state of the substrate surface and the presence of a catalyst on it also play an important role. Experiments on the deposition of carbon films in the pulsed regime of plasma excitation show the possibility of changing the phase composition of the film by varying both the pulse repetition rate and the off-duty factor. At the same average microwave power, the rate of film deposition in the pulsed regime of plasma excitation is lower than that in a continuous discharge; however, the growth rate of the graphite phase decreases insignificantly.     

Analysis of the DRD4 Gene Polymorphism in Populations of Russia and Neighboring Countries

Allele and genotype frequencies of the VNTR polymorphism in the third exon of humanDRD4 gene were determined in 544 individuals living in Russia (Russians, Bashkirs, Tatars, and Mordovians) and in the neighboring countries (Kazakhs and Ukrainians). The data obtained were compared with the allele frequency distribution patterns reported for the populations of Eurasia. Similarly to other Eurasian populations, in our population samples R4 allele was prevalent (64 to 87%). The frequency of this allele in the populations of Western Europe constitute 61 to 71%, while in the populations of Asia it varies from 74 to 96%. In this respect, the populations studied occupied the intermediate position. In the samples examined the R7 allele frequency decreased from 7% in Ukrainians to 1% in Bashkirs, while in Kazakhs and Mordovians the allele was absent. This finding was consistent with theR7 allele distribution pattern in the populations of Eurasia, characterized by higher frequency in the West and lower frequency or absence of the allele in the East. In the group of 22 Eurasian populations, the R7 allele frequency negatively correlated with the frequency of the R4 allele (r = -0.86 at P < 0.001). Unlike the R4 and R7 alleles, the frequency of which changed in the eastward direction, the R2 allele frequency distribution displayed slightly expressed latitudinal increase southwards. The DRD4 genotype distribution deviated from the equilibrium in most of the samples examined. In some samples, statistically significant increase of the R2/R2homozygotes frequency was demonstrated. One of the possible explanations of this phenomenon is assortative mating with respect to phenotypic (behavioral) allele manifestation. The data obtained can serve as the basis for the investigation of the possible role of the DRD4 alleles as the risk factors for the development of alcoholism and other types of addictions.     

VNTR Polymorphisms of the Serotonin Transporter and Dopamine Transporter Genes in Male Opiate Addicts

VNTR polymorphisms of the serotonin transporter (hSERT) and dopamine transporter (DAT1) gene were studied in male opiate addicts. Samples of ethnic Russians and ethnic Tatars did not differ in genotype and allele frequencies. Homozygosity at hSERT (especially 10/10) was associated with early opiate addiction, while genotype 12/10 proved to be protective. In the case of DAT1, genotype 9/9 was associated with early opiate addiction. The combination of hSERT genotype 10/10 with DAT1 genotype 10/10 was shown to be a risk factor of opiate abuse under 16 years of age.