Electronic correlation effects and the Coulomb gap at finite temperature

We have investigated the effect of the long-range Coulomb interaction on the one-particle excitation spectrum of n-type Germanium, using tunneling spectroscopy on mechanically controllable break junctions. The tunnel conductance was measured as a function of energy and temperature. At low temperatures, the spectra reveal a minimum at zero bias voltage due to the Coulomb gap. In the temperature range above 1 K the Coulomb gap is filled by thermal excitations. This behavior is reflected in the temperature dependence of the variable-range hopping resitivity measured on the same samples: Up to a few degrees Kelvin the Efros-Shkovskii ln$R \propto T^{-1/2}$ law is obeyed, whereas at higher temperatures deviations from this law are observed, indicating a cross-over to Mott's ln$R \propto T^{-1/4}$ law. The mechanism of this cross-over is different from that considered previously in the literature.Comment: 3 pages, 3 figure

Structure and spatial distribution of Ge nanocrystals subjected to fast neutron irradiation

The influence of fast neutron irradiation on the structure and spatial distribution of Ge nanocrystals (NC) embedded in an amorphous SiO2 matrix has been studied. The investigation was conducted by means of laser Raman Scattering (RS), High Resolution Transmission Electron Microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The irradiation of NC-Ge samples by a high dose of fast neutrons lead to a partial destruction of the nanocrystals. Full reconstruction of crystallinity was achieved after annealing the radiation damage at 800 deg. C, which resulted in full restoration of the RS spectrum. HR-TEM images show, however, that the spatial distributions of NC-Ge changed as a result of irradiation and annealing. A sharp decrease in NC distribution towards the SiO2 surface has been observed. This was accompanied by XPS detection of Ge oxides and elemental Ge within both the surface and subsurface region

About low field memory and negative magnetization in semiconductors and polymers

Ginzburg-Landau bulk magnetization of itinerant electrons can provide a negative effective field in the Weiss model by coupling to localized magnetic moments. The coupling enforces remnant magnetization, which can be negative or positive depending on the sample magnetic history. Stable magnetic susceptibility of coupled nonequilibrium subsystems with magnetization reversal is always positive. Gauss-scale fields could be expected for switching between negative and positive remnant moments in semiconductors with coupling at ambient temperatures. Negative magnetization in ultra-high conducting polymers is also discussed within the developed framework.Comment: 8 pages, no figure

Tribological properties of hydraulic fluids modified by peat-based additives

The paper presents physicochemical investigations of the structure and properties of a nano-modifier synthesized from peat, the local raw material subjected to pyrolysis in air-free conditions. This nano-modifying additive is a combination of various forms of nanocarbon and polar and non-polar adsorbing materials such as silica (SiO[2]), calcium carbonate (CaCO[3]) and carbon (C). Different nanocarbon forms (nanotubes, fullerenes, nanodiamonds, nanofiber, nanodispersed carbon) used in different proportions with micro and macro peat components give multifunctional properties to the synthesized nano-modifier and the ability to positively change tribological properties of hydraulic fluids and oil lubricants. Test results of type TMT-600 show that its different percentage is required to modify tribological properties of the steel tribocouple under different loading conditions. At 0.5 wt.% content of this nano-modifier, stabilization of the friction ratio and an increase of seizure load are observed

Influence of trigonal warping on interference effects in bilayer graphene

Bilayer graphene (two coupled graphitic monolayers arranged according to Bernal stacking) is a two-dimensional gapless semiconductor with a peculiar electronic spectrum different from the Dirac spectrum in the monolayer material. In particular, the electronic Fermi line in each of its valleys has a strong p -> -p asymmetry due to trigonal warping, which suppresses the weak localization effect. We show that weak localization in bilayer graphene may be present only in devices with pronounced intervalley scattering, and we evaluate the corresponding magnetoresistance

Integrated solution for patients of a very high cardiovascular risk. Final results

Secondary prevention should be actively implemented at all stages of treatment and rehabilitation of patients after acute coronary syndrome (ACS). The integration of remote monitoring of patients with the transfer of vital and laboratory data into clinical practice seems promising.Aim. To evaluate the clinical and patient-centered effectiveness of the original 12-month combined face-to-face and telecare program in patients with recent ACS.Material and methods. For the present analysis the data from 84 (out of 100) patients (median age, 56 (50;61) years, 70 males) was used. These patients had to have hypertension and/or type 2 diabetes and an ACS with percutaneous revascularization within 12 months. Their low-density lipoprotein cholesterol (LDL-C) had to be above 2,4 mmol/L. Telehealth program supplemented routine care. A program contained electronic self-control diaries for blood pressure (BP) and lipid profile, and teleconsulting service (text chat). Mandatory face-to-face visits were carried out at 3 and 12 months after the enrollment. The primary end point was ∆LDL-C. Additional clinical and patient-specific endpoints were evaluated.Results. At the 12-month visit, there was a significant decrease in LDL-C by 1,6 (-2,3;-0,9) mmol/L. Besides the initial LDL-C value, the decrease in LDL-C was associated with the proper adherence to keeping diaries of BP and lipid profile (β=0,7), and the number of text messages sent by the doctor in the 1st month after the enrollment (β=0,04). In more adherent patients, the ∆LDL-C was greater by 0,49 mmol/L (95% CI (-1,2; -0,1)) after adjustment for abovementioned covariates. In 35 patients (42%), target LDL-C was achieved, in 60 patients (71%) — a decrease ≥1 mmol/l. Other lipids also have changed for the better. Moreover, adherent patients were twice as likely to achieve the target LDL-C (OR 2,2; 95% CI (0,6; 3,8)) than non-adherent ones. A decrease in office systolic BP by 5,8 mm Hg was shown (p=0,03). The number of physician-to-patient messages exceeded those from patients to physician (median 143 and 111 per patient for 12 months, respectively). The quality of life has improved, but only in terms of emotions. Satisfaction with the program remained high at all timepoints of the study.Conclusion. Our study showed the effectiveness of the integrated care in ACS patients with the telehealth tool included. Commitment to BP self-monitoring, as well as active consultative support at the first stages of rehabilitation, contributes to additional dynamic control of lipid profile, timely correction of lipid-lowering therapy with the achievement of the target LDL-C level. Most of the patients did not experience any difficulties in using the program and are ready to recommend integrated approach to other peers

Integrated solution for very high cardiovascular risk patients. Rationale and design of a pilot study

Coronary artery disease (CAD) is the most common cardiovascular disease and the leading cause of morbidity and mortality. Acute coronary syndrome (ACS) as an abrupt destabilization of CAD, multiplies the risk of cardiovascular events. To reduce the incidence of recurrent cardiovascular events, timely tackling potentially reversible risk factors such as hypertension and/or hyperglycemia is imperative. However, a solid basis for a secondary prevention lies in the treatment of dyslipidemia and begins in the first hours of hospital admission. Despite considerable evidence regarding the efficacy and safety of lipid-lowering therapy, averagely only one third of patients maintain control of lipids. The main challenges are low adherence, poor continuity of medical care, and the lack of an ambulatory routine follow-up. Telehealth solutions are believed to address these barriers and may be considered as an add-on to in-person patient care. Telemonitoring of vital and laboratory parameters, remote patient counseling can be introduced into routine care delivery. Telemedicine shows promise for fostering better clinical effect, and provides health-related quality of life improvement.It is planned to conduct a pilot observational study aimed to create and to test an integrated solution, i.e. telemonitoring and remote counseling in patients of very high cardiovascular risk with ACS followed by myocardial revascularization. The goal is to determine the clinical effectiveness, i.e achievement of target values of blood pressure, lipid profile and glycemia, and patient-centeredness of this approach