Liquid phase diffusion growth of SiGe single crystals under magnetic fields

The manuscript presents the results of a combined experimental and modeling study on the Liquid Phase Diffusion (LPD) growth of single crystal SixGe1-x on Germanium with and with the application of magnetic fields. Although the LPD process is mainly diffusion driven through out the growth period, strong natural thermosolutal convection occurs in the first five hours of growth, and the growth interface is concave to the melt. Applied rotating and static magnetic fields were considered to examine the growth and silicon dissolution processes in the LPD system. Results show that the application of a combined applied magnetic is beneficial

Optical properties of SiGe single crystals grown by liquid phase diffusion

In this article, we present measurements for the pseudo-optical functions of germanium-rich SixGe1-x (0.000<x<0.100) single-crystals(grown by Liquid Phase Diffusion; LPD) using spectroscopic ellipsometry and photo reflectance techniques in the energy range of 1.72–3.20 eV. The E1 interband transition energies are obtained from numerically differentiated optical spectra for various crystal compositions. It was shown that the values of E1 interband transition energy determined by both the ellipsometric and photo reflectance measurements for germanium-rich SixGe1-x single-crystals are in agreement with those of bulk SiGe crystals reported in the literature[21–24].The interband transition energies are found to be in the range of 2.100 and 2.215 eV for the composition values of 0.000<x0.100. The surface morphology of the crystals assayed via atomic force microscopy shows fibrous surfaces with the average grain size of 250 nm. The measured root-mean-square (rms) roughness and maximum height are in the range of 3.78–5.40 and 32.42–67.84 nm, respectively, with increasing germanium composition

Influence of supercritical CO2 cooling on tool wear and cutting forces in the milling of Ti-6Al-4V

Ti-6Al-4V is known as a difficult-to-machine alloy due to its low thermal conductivity which limits the material’s machinability causing rapid tool wear. Supercritical CO2 is an environmentally friendly alternative cooling technique that can improve the machinability of Ti-6Al-4V enabling higher productivity. This study investigates the variation in tool life and cutting force coefficients when milling Ti-6Al-4V with scCO2, scCO2 combined with minimum quantity lubrication and flood coolant. Results from cutting trials carried out at 60 m/min have shown that when the chip load is controlled, substantial improvement in tool life can be obtained with scCO2+MQL compared to flood coolant with no significant change in cutting force coefficients. However, it has been found that the capabilities of scCO2 are limited outside the practical speed and feed range resulting in no additional benefit in tool life and sharp increase in cutting force coefficients due to higher thermal gradient and excessive tool wear

Strength of selection pressure is an important parameter contributing to the complexity of antibiotic resistance evolution

Revealing the genetic changes responsible for antibiotic resistance can be critical for developing novel antibiotic therapies. However, systematic studies correlating genotype to phenotype in the context of antibiotic resistance have been missing. In order to fill in this gap, we evolved 88 isogenic Escherichia coli populations against 22 antibiotics for 3 weeks. For every drug, two populations were evolved under strong selection and two populations were evolved under mild selection. By quantifying evolved populations' resistances against all 22 drugs, we constructed two separate cross-resistance networks for strongly and mildly selected populations. Subsequently, we sequenced representative colonies isolated from evolved populations for revealing the genetic basis for novel phenotypes. Bacterial populations that evolved resistance against antibiotics under strong selection acquired high levels of cross-resistance against several antibiotics, whereas other bacterial populations evolved under milder selection acquired relatively weaker cross-resistance. In addition, we found that strongly selected strains against aminoglycosides became more susceptible to five other drug classes compared with their wild-type ancestor as a result of a point mutation on TrkH, an ion transporter protein. Our findings suggest that selection strength is an important parameter contributing to the complexity of antibiotic resistance problem and use of high doses of antibiotics to clear infections has the potential to promote increase of cross-resistance in clinics

Evaluation of Trastuzumab-induced early cardiac dysfunction using two-dimensional Strain Echocardiography

Abstract Aim: Trastuzumab, a chemotherapeutic agent used in the treatment of breast cancer. has been shown to induce subclinical left ventricular (LV) dysfunction during a three to six month period as evidenced by strain echocardiographic examination without any change occurring in the ejection fraction of LV. The present study evaluated the presence of subclinical LV dysfunction using strain echocardiography 1 day and 7 days after the initiation of trastuzumab therapy. Material and methods: The patients with breast cancer receiving adjuvant trastuzumab therapy underwent 2-dimensional, tissue Doppler, and strain echocardiographic examination at baseline and 1 day and 7 days after therapy. LV global longitudinal strain (GLS), global circumferential strain (GCS) values, and other echocardiographic parameters were calculated. Results: A total of 40 females, mean age 50±10 years, were evaluated. Of these patients, 97% received anthracycline and 73% received radiotherapy before the initiation of trastuzumab therapy. No change was observed in any of the echocardiographic parameters 1 day after the initiation of trastuzumab therapy (p&gt;0.05). The LV ejection fraction, tissue Doppler parameters, and GCS values did not show any changes 7 days after the initiation of therapy, whereas significant decreases were observed in GLS value (19.2±4.0% vs. 17.2±3.4, p=0.001) and systolic annular velocity of the lateral LV wall (S&apos; velocity) (10.5±3.2 vs. 8.6±2.2, p=0.002). Conclusion: Trastuzumab therapy is associated with subclinical LV dysfunction as early as 7 days after initiation of the therapy as evidenced by the decreases in GLS value of LV and systolic annular velocity of the lateral LV wall

Growth of bulk SiGe single crystals by liquid phase diffusion method: experimental and computational aspects

SiGe is an emerging semiconductor material with many promising applications in high-speed micro electronics and thermo-photovoltaics. In light of significant differences in physical properties of constituent elements, it is still a challenge to grow bulk SiGe single crystals with uniform composition and low defect density. Thus, it is essential to scrutinize the solidification behaviour of SiGe system. Hence, this book presents a combined experimental and modelling study for the growth of SiGe single crystals by a new solution growth process called Liquid Phase Diffusion (LPD). Following a brief introduction of the subject, the crystal structure, phase diagram, growth techniques used for producing SiGe single crystals and their place in the overall scheme of SiGe alloy systems are presented. The development of a macroscopic mixture model is presented to model the LPD growth system. The LPD growth system is examined using two- and three-dimensional transient simulations. The design, construction, and testing of the LPD growth system are presented along with the experimental results and characterization of grown crystals

Anterior Segment Analysis and Evaluation of Corneal Biomechanical Properties in Children with Joint Hypermobility

Objectives: To compare anterior segment parameters and biomechanical analysis of the cornea in children with joint hypermobility (JH) and healthy children