Influence of the preliminary annealing conditions on step motion at the homoepitaxy on the Si(100) surface

In this paper, the motion of steps SA and SB on the Si(100) surface in the process of Si Molecular beam epitaxy (MBE) is explored. The study was carried out by means of the reflection intensity dependence behavior analysis of reflection high-energy electron diffraction (RHEED) corresponding to the (2×1) and (1×2) reconstructions. Superstructural rearrangement from a two-domain to a single-domain surface is associated with the bilayer step formation, which occurs due to the different motion rates of the steps SA and SB. Based on the research conducted, the conditions under which the step doubling occurs were determined. A behavior analysis of the diffraction reflection intensity dependences showed that an increasing of preliminary annealing time and temperature facilitates to the faster convergence of the steps SA and SB, but to the slower recovery of the initial surface. The presented experimental results indicate that step movement rate difference depends on the step A edge kink density

Temperature spectra of conductance of Ge/Si p-i-n structures with Ge quantum dots

Abstract This work presents results of investigation of Ge/Si p-i-n structures with Ge quantum dots in the i-region by the method of admittance spectroscopy. The structures contain multiple layers with Ge quantum dots separated by thin 5 nm layers of Si in the intrinsic region. Two peaks are observed on the temperature dependences of conductance of the investigated heterostructures. It is revealed that the second peak is broadened and corresponds to a system of closely lying energy levels

Admittance spectroscopy of Ge/Si p-i-n structures with Ge quantum dots

The experimental results on synthesis of Si/Ge p-i-n structures with Ge quantum dots in the i-region and their investigation by the method of admittance spectroscopy are presented. The activation energies of the emission process from localized states are calculated for two types of structures. Current-voltage characteristics without illumination and under illumination are measured

The Trusted UHF Receiver for Radio Frequency Identification of Critical Infrastructure Objects

Results of designing the low-noise amplifier, quadrature demodulator, and baseband amplifier with an integrated low-pass filter for the UHF radio frequency identification receiver are presented. IP-blocks are designed for implementation in the domestic CMOS 180 nm technology process. The low-noise amplifier is implemented with integrated single pole double throw switches based on the MOSFETs which are needed for bypass mode realization at the RF input. The benefits of this approach are increased input linearity of the receiver by no less than 30 dB with an increase of a noise figure. The quadrature demodulator is realized according to a typical design based on the passive MOSFET mixer core. The programmable-gain baseband amplifier is implemented with an integrated low-pass filter based on Tow-Thomas biquad architecture. IP-blocks designed for use in an RFID reader transceiver VLSI IC with sensitivity value no more than -75 dBm and input linearity value not less than 10 dBm in a «Talk» mode. The trustiness of the receiver is provided by the full-cycle design procedure and verification under experimental investigation. The electric parameters values of the proposed receiver correspond to foreign VLSIs implemented in a CMOS process with the same technology nodes. Thus, it is important to design the domestic ISO 18000-6C reader equipment intended for critical infrastructure

The Design Technique for Power Management Unit of the Tag IC for Radio Frequency Identification of Critical Infrastructure Objects

The ultra-high frequency (UHF) tag IC’s main part of the power management unit (PMU) design technique is presented. The technique is a step-by-step algorithm for designing a PMU and consists of five interrelated stages. At the first stage, the requirements for the parameters of the PMU (output voltage, output DC power, efficiency, output capacitor capacity) and the Q-factor of the tag analog front-end are determinates. At the second stage, the design of an electrical circuit of a voltage multiplier (VM) is carried out. VM is required to convert the voltage of the input radio frequency (RF) signal into an DC voltage. During the third stage, the design of the electrical circuit of the DC voltage limiter is carried out, which is necessary to reduce the output voltage of VM to a safe level. The result of stage 4 is an electrical circuit of surge protection designed to provide the required level of immunity of the tag IC to the effects of electrostatic discharge and a high-power RF signal. As part of the final stage, the evaluation and alignment with the required Q-factor value of the tag IC analog front-end is carried out. The proposed technique can be used for the development of domestic UHF tag ICs (ISO 18000-6C, GJB 7377.1, etc.) based on CMOS technological processes, including ICs designed for radio frequency identification of critical infrastructure objects. Using the presented technique, the design of a PMU with an estimated efficiency value of 70%, an estimated Q-factor of the analog front-end of less than 15 at an RF input signal power of -12.7 dBm was performed

Role of Phagocytosis in the Pro-Inflammatory Response in LDL-Induced Foam Cell Formation; a Transcriptome Analysis

Excessive accumulation of lipid inclusions in the arterial wall cells (foam cell formation) caused by modified low-density lipoprotein (LDL) is the earliest and most noticeable manifestation of atherosclerosis. The mechanisms of foam cell formation are not fully understood and can involve altered lipid uptake, impaired lipid metabolism, or both. Recently, we have identified the top 10 master regulators that were involved in the accumulation of cholesterol in cultured macrophages induced by the incubation with modified LDL. It was found that most of the identified master regulators were related to the regulation of the inflammatory immune response, but not to lipid metabolism. A possible explanation for this unexpected result is a stimulation of the phagocytic activity of macrophages by modified LDL particle associates that have a relatively large size. In the current study, we investigated gene regulation in macrophages using transcriptome analysis to test the hypothesis that the primary event occurring upon the interaction of modified LDL and macrophages is the stimulation of phagocytosis, which subsequently triggers the pro-inflammatory immune response. We identified genes that were up- or downregulated following the exposure of cultured cells to modified LDL or latex beads (inert phagocytosis stimulators). Most of the identified master regulators were involved in the innate immune response, and some of them were encoding major pro-inflammatory proteins. The obtained results indicated that pro-inflammatory response to phagocytosis stimulation precedes the accumulation of intracellular lipids and possibly contributes to the formation of foam cells. In this way, the currently recognized hypothesis that the accumulation of lipids triggers the pro-inflammatory response was not confirmed. Comparative analysis of master regulators revealed similarities in the genetic regulation of the interaction of macrophages with naturally occurring LDL and desialylated LDL. Oxidized and desialylated LDL affected a different spectrum of genes than naturally occurring LDL. These observations suggest that desialylation is the most important modification of LDL occurring in vivo. Thus, modified LDL caused the gene regulation characteristic of the stimulation of phagocytosis. Additionally, the knock-down effect of five master regulators, such as IL15, EIF2AK3, F2RL1, TSPYL2, and ANXA1, on intracellular lipid accumulation was tested. We knocked down these genes in primary macrophages derived from human monocytes. The addition of atherogenic naturally occurring LDL caused a significant accumulation of cholesterol in the control cells. The knock-down of the EIF2AK3 and IL15 genes completely prevented cholesterol accumulation in cultured macrophages. The knock-down of the ANXA1 gene caused a further decrease in cholesterol content in cultured macrophages. At the same time, knock-down of F2RL1 and TSPYL2 did not cause an effect. The results obtained allowed us to explain in which way the inflammatory response and the accumulation of cholesterol are related confirming our hypothesis of atherogenesis development based on the following viewpoints: LDL particles undergo atherogenic modifications that, in turn, accompanied by the formation of self-associates; large LDL associates stimulate phagocytosis; as a result of phagocytosis stimulation, pro-inflammatory molecules are secreted; these molecules cause or at least contribute to the accumulation of intracellular cholesterol. Therefore, it became obvious that the primary event in this sequence is not the accumulation of cholesterol but an inflammatory response

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN