Coherent Phonons in Bismuth Film Observed by Ultrafast Electron Diffraction

The generation of coherent phonons in polycrystalline bismuth film excited with femtosecond laser pulse is observed by ultrafast time-resolved electron diffraction. The dynamics of the diffracted intensities from the (110), (202), and (024) lattice planes show pronounced oscillations at 130-150 GHz. The origin of these coherent acoustic phonons is discussed in view of optical phonon decay into two acoustic phonons. Different drop times in the intensity of the diffraction orders are observed and interpreted as anisotropy in the energy transfer rate of coherent optical phonons

Friction and Wear Characteristics of C/Si Bi-layer Coatings Deposited on Silicon Substrate by DC Magnetron Sputtering

The tribological behavior of carbon/silicon bi-layer coatings deposited on a silicon substrate by DC magnetron sputtering was assessed and compared to that of amorphous carbon and silicon coatings. The motivation was to develop a wear resistant coating for silicon using thin layers of amorphous carbon and silicon. Wear tests were conducted by sliding a stainless steel ball against the coating specimens under applied normal loads in the range of 20 * 50 mN. Results showed that the wear rate of the bi-layer coating was strongly dependent on the ratio of thickness between the carbon and silicon layers. The wear rate of the bi-layer coating with 25 nm thick carbon and 102 nm thick silicon layers was about 48 and 20 times lower than that of the single-layer amorphous carbon and amorphous silicon coating, respectively. In addition, the steady-state friction coefficient of the bi-layer coating could be decreased to 0.09 by optimizing the thickness of the layer. Finally, a model for the wear reduction mechanism of the carbon/silicon bi-layer coating was proposed

States and properties of metallic systems at a threshold breakdown of the through holes under power laser action (part 2).

Threshold breakdown of the through holes by power laser radiation of metallic foils is considered as response of metallic system to laser radiation. Binding experimentally determined response to the absolute temperature scale allows to determine the value of the imaginary part of the generalized susceptibility depending on temperature, the critical temperature of the transition “liquid metal - gas”, states of the electronic subsystems at this temperature, and the reflectance coefficient values

States and Properties of Metallic Systems at a Threshold Breakdown of the Through Holes Under Power Laser Action. Threshold Breakdown of Through Holes in Metal Foils by Powerful Laser Radiation (Part 1)

Energy of threshold breakdown of through holes in metal foils of different thicknesses by powerful laser radiation is investigated experimentally. Properties of foil matter at “liquid metalgas” phase transition are revealed. One of controlled parameters of the threshold breakdown is the outlet on the shady side of the target. The threshold breakdown hole is outlet of hole for a given foil thickness when further decrease of energy is not able to create

States and Properties of Metallic Systems at a Threshold Breakdown of the Through Holes Under Power Laser Action. Threshold Breakdown of Through Holes in Metal Foils by Powerful Laser Radiation (Part 1)

Energy of threshold breakdown of through holes in metal foils of different thicknesses by powerful laser radiation is investigated experimentally. Properties of foil matter at “liquid metalgas” phase transition are revealed. One of controlled parameters of the threshold breakdown is the outlet on the shady side of the target. The threshold breakdown hole is outlet of hole for a given foil thickness when further decrease of energy is not able to create

Quantitative assessment of hepatic function by indocyanine green clearance test

The purpose of the investigation was to study the informative and prognostic values of a dynamic hepatic function test using indocyanine green (ICG) in cirrhotic patients. The investigation covered 149 patients with hepatic cirrhosis (a study group) and 20 patients without signs of liver disease (a control group). The plasma ICG elimination rate (PICGER) was significantly lower in the study group (7.6±3.4 and 22.9±4.2% per min in the study and control groups, respectively; p < 0.001). With the progression of hepatocellular dysfunction revealed by the ChildPugh criteria, the indocyanine clearance values became progressively worse. In cirrhotic patients, PICGER correlated with the levels of total bilirubin (r = -0.501; p < 0.001), albumin (r = 0.494; p < 0.001), international normalized ratio (r = 0.475; p < 0.001), and the histological activity index of the necroinflammatory process in the hepatic parenchyma (r =-0.579; p < 0.001). In these patients, median survival was significantly higher in cases with prompter ICG elimination and, at a PICGER of > 7, 5 to 7, and <5% per min, it was 20, 11.5, and 6 months (χ2  = 51.9; p<0,001). Analysis of ROC curves demonstrated a greater prognostic value of the ICG clearance test than the Child-Pugh and MELD criteria (statisticPER, 0.852±0.032; c-statisticCHILD, 0.767±0.039, с-statisticMELD, 0.758±0.041; p < 0.001). The sensitivity and specificity of the clearance test in the prediction of annual survival were 86.5 and 76.8%, respectively. Thus, the determination of ICG clearance is a highly informative and specific dynamic test that estimates hepatic functional reserves. The inclusion of this criterion into the existing scales for rating the severity of hepatocellular dysfunction permits improvement of the diagnostic and prognostic efficiency of their use

Structural transformation in C/Si multilayer after annealing

Amorphous C/Si multilayers were prepared by DC magnetron sputtering technique and investigated by transmission electron microscopy and low-angle x-ray diffraction methods after annealing at 650 and 950 °C. The amorphous interlayers of 0.5 − 0.6 nm thick were found at C/Si and Si/C interfaces being of different density and composition. Amorphous structure of the multilayer is stable up to 950 °C when crystallization of α-SiC occurs and voids form in α-Si layer.Изготовленные методом прямоточного магнетронного распыления аморфные многослойные композиции C/Si были исследованы методами просвечивающей электронной микроскопии и малоугловой рентгеновской дифракции после отжигов при температуре 650 и 950 °C. На границах раздела C/Si и Si/C обнаружены аморфные перемешанные зоны толщиной 0.5 – 0.6 нм c различными плотностью и составом. Аморфная структура многослойной композиции стабильна вплоть до 950 °C, когда наблюдается формирование пор в слоях α-Si и кристаллизация α-Si

The preadolescent acne microbiome: A prospective, randomized, pilot study investigating characterization and effects of acne therapy.

BACKGROUND/OBJECTIVES: Acne, a common pediatric disease, tends to be more comedonal in preadolescents, whereas older individuals are more likely to have inflammatory lesions in addition to comedones. Thus the microbiome of preadolescents may be different. In this pilot study we aimed to characterize the preadolescent acne microbiome, compare the microbiome in preadolescents with and without acne, and investigate changes in the microbiome after topical treatment with benzoyl peroxide or a retinoid in a small cohort of preadolescents. METHODS: Participants were 7-10 years of age with (intervention group) or without (control group) acne and were recruited during routine outpatient dermatology visits. Baseline questionnaires, physical examination, and pore strip application were performed for all participants. Intervention group participants were randomized to receive topical therapy with benzoyl peroxide 5% gel or cream or tretinoin 0.025% cream. Participants with acne were followed up 8-10 weeks later and pore strip application was repeated. RESULTS: Preadolescents with acne were colonized with a greater diversity of cutaneous bacteria than controls and the most commonly identified bacterium was Streptococcus. The number of bacterial species and phylogenetic diversity decreased after treatment with benzoyl peroxide and tretinoin. CONCLUSION: The predominant bacteria in microbiome studies of adult acne is Propionibacterium, whereas in this pediatric population we saw a lot of Streptococcus bacteria. After treatment, the microbiomes of intervention group participants more closely resembled those of control group participants