Forceless spontaneous delamination of high-aspect ratio fluorohectorite into monolayer nanosheets in chloroform.

One-dimensional dissolution of a layered compound in a nonpolar organic solvent is reported for the first time. A high-aspect ratio fluorohectorite modified with a cationic surfactant (dioctadecyldimethylammonium) showed spontaneous delamination into monolayer nanosheets in chloroform.

High-permittivity Solvents Increase MXene Stability and Stacking Order Enabling Ultraefficient Terahertz Shielding.

2D transition metal carbides and nitrides (MXenes) suggest an uncommonly broad combination of important functionalities amongst 2D materials. Nevertheless, MXene suffers from facile oxidation and colloidal instability upon conventional water-based processing, thus limiting applicability. By experiments and theory, It is suggested that for stability and dispersibility, it is critical to select uncommonly high permittivity solvents such as N-methylformamide (NMF) and formamide (FA) (ε  = 171, 109), unlike the classical solvents characterized by high dipole moment and polarity index.

Fabricating defogging metasurfaces a water-based colloidal route.

Metamaterials possess exotic properties that do not occur in nature and have attracted significant attention in research and engineering. Two decades ago, the field of metamaterials emerged from linear electromagnetism, and today it encompasses a wide range of aspects related to solid matter, including electromagnetic and optical, mechanical and acoustic, as well as unusual thermal or mass transport phenomena. Combining different material properties can lead to emergent synergistic functions applicable in everyday life.

Effect of Tempforming on Strength and Toughness of Medium-Carbon Low-Alloy Steel.

The effect of tempforming on the strength and fracture toughness of 0.4%C-2%Si-1%Cr-1%Mo-VNb steel was examined. Plate rolling followed by tempering at the same temperature of 600 °C increases yield stress by 25% and the Charpy V-notch impact energy by a factor of ~10.

Configurations and Sensory Properties of the Stereoisomers of 2,6-Dimethyl-4-propyl-1,3-oxathiane and 2,4-Dimethyl-6-propyl-1,3-oxathiane.

The heterocyclic compounds 2,6-dimethyl-4-propyl-1,3-oxathiane and 2,4-dimethyl-6-propyl-1,3-oxathiane were obtained by condensing 4-mercapto-2-heptanol and 2-mercapto-4-heptanol, respectively, with acetaldehyde. For both, separation of the eight stereoisomers was achieved capillary gas chromatography using heptakis(diethyl--butyldimethylsilyl)-β-cyclodextrin as the chiral stationary phase. Their configurations were assigned by combinations of enzyme-catalyzed kinetic resolutions, HPLC separations, and assessments of NMR data.

Osmotic Swelling of Sodium Hectorite in Ternary Solvent Mixtures: Nematic Liquid Crystals in Hydrophobic Media.

The swelling of clay minerals in organic solvents or solvent mixtures is key for the fabrication of polymer nanocomposites with perfectly dispersed filler that contain only individual clay layers. Here, we investigated the swelling behavior of sodium hectorite in different ternary solvent mixtures containing methanol, acetonitrile, ethylene glycol, or glycerol carbonate with minimal amounts of water. We found that in these mixtures, less water is required than in the corresponding binary mixtures to allow for complete delamination by repulsive osmotic swelling.

Absolute Configurations and Sensory Properties of the Stereoisomers of a Homologous Series (C6-C10) of 2-Mercapto-4-alkanols.

A homologous series (C6-C10) of 2-mercapto-4-alkanols was obtained by the addition of thioacetic acid to the respective alkenones and subsequent reduction with LiAlH. Gas chromatographic separation of the stereoisomers was achieved using chiral stationary phases. Their absolute configurations were assigned by the correlation of H NMR data and enzyme-catalyzed kinetic resolutions.

HIV risk behavior in male and female Russian sexually transmitted disease clinic patients.

Russia is experiencing one of the fastest growing HIV epidemics in the world. Russian sexually transmitted disease (STD) clinic patients are at elevated risk for infection with HIV and other STDs due to unsafe sexual behaviors. Future risk reduction intervention efforts for this group must be grounded in a solid understanding of the factors associated with risky behaviors.

[Carotid atherosclerosis detectability in patients with coronary heart disease and arterial hypertension].

Aim: To assess detectability of carotid atherosclerosis in patients with coronary heart disease (CHD) and arterial hypertension (AH) by the data of ultrasonic screening, to study location and detectability of atherosclerotic lesion of common carotid arteries, internal carotid arteries, external carotid arteries in correlation with basic disease.

Material And Methods: Ultrasonic screening of brachyocephalic arteries was made in 469 patients: with CHD (n = 239), AH (n = 230) including patients with concomitant postinfarction cardiosclerosis (PICS) and moderate chronic cerebrovascular failure (CCVF).

Results: Ultrasonic angiography detected atherosclerotic carotid artery lesion in patients with CHD and PICS (81.

A comparison of HIV/AIDS knowledge and attitudes of STD clinic clients in St. Petersburg, Russia and Milwaukee, Wi, USA.

Over the last decade, Russia has experienced alarming increases in rates of HIV and other sexually transmitted diseases (STDs). Most empirically validated HIV-prevention studies have been conducted in the United States or other developed nations and it is unclear the extent to which these techniques may be useful in the different conditions found in Eastern Europe. The present study compared HIV/AIDS knowledge, attitudes toward condoms, perceived vulnerability to HIV, and attitudes towards HIV testing in samples of 400 Russian and 401 American STD clinic patients.

[Diagnosis of structural changes] of the brain in patients with coronary and asymptomatic carotid atherosclerosis].

Aim: To compare echomorphostructure of atherosclerotic plaques and vascular stenosis degree with structural changes of the brain according to MR image in patients with combined atherosclerotic affection of coronary and carotid arteries in an asymptomatic course of carotid atherosclerosis.

Material And Methods: MR imaging was made in 53 men aged 44 to 78 years with stenosing atherosclerotic affection of the internal carotid arteries. Vascular obstruction reached 30-80%.

[Abnormal cerebrovascular reactivity in patients with asymptomatic atherosclerosis of the carotid arteries].

The study included 53 patients (males at the age of 44-78 years) with ischemic heart disease and arterial hypertension with asymptomatic unilateral atherosclerotic affection of carotid arteries (CA). Ultrasonic investigation registered 30-80% stenosis of carotid arteries in the absence of neurological deficit. Cerebrovascular reactivity was assessed by means of the hypercapnic hypoxic test (HHT) including breathing via additional "dead space" for 3 min.

HIV/AIDS knowledge and attitudes of STD clinic attendees in St. Petersburg, Russia.

Over the last several years, Russia has experienced dramatic increases in rates of HIV and other sexually transmitted disease (STDs). This study examined HIV/AIDS knowledge, attitudes toward condoms, and sources of information about HIV in a sample of 200 male and 200 female Russian STD clinic patients. Study participants displayed substantial knowledge deficits concerning AIDS and HIV transmission.

[Prognostication of hemodynamic efficacy of surgical correction of chronic coronary insufficiency based on stress test with nitroglycerine].

In our previous studies we demonstrated possibility of the use of stress echocardiography with sublingual administration of nitroglycerine for detection of viable myocardium. Basing on data about myocardial and cerebrovascular reserves obtained during nitroglycerine tests we created mathematical model for prediction of hemodynamic effectiveness of coronary bypass surgery. Stress echocardiography, Doppler echography of middle cerebral and internal carotid arteries with nitroglycerine were carried out in 80 patients with coronary artery disease before myocardial revascularization.

[Dynamics of left ventricular remodeling in patients with acute myocardial infarction].

Dynamics of structural and functional left ventricular parameters was investigated in 51 patients with acute anterior myocardial infarction by means of serial (on days 1, 2, 3, 5, 7, 10 and 21 of infarction) echocardiographical study. Increase of end-diastolic volume index relative to initial values became significant on 5th-7th days and continued to progress until 3rd week of infarction. Left ventricular cavity became dilated and attained more occurred shape predominantly at the account of increased transverse diameters.

[Minor stenosis of carotid arteries: differential approach in diagnosis and surgical treatment].

The results of treatment of 161 patients with atherosclerotic small degree stenoses of carotid arteries (up to 50% of diameter) were analyzed. From them 67 patients underwent operations for chronic cerebro-vascular failure and 11 patients--for acute cerebro-vascular failure. 31 patients, who had contraindications for surgery or refused it, plasmapheresis procedures were carried on, 52 patients with asymptomatic carotid arteries' disease underwent conservative treatment.

[The cerebral hemodynamics of patients with ischemic heart disease during transesophageal electrical stimulation of the left atrium].

In 26 patients with coronary heart disease, transesophageal atrial pacing was used to study cerebral hemodynamics from brain tomoscintigraphic findings as compared to the severity of induced of myocardial ischemia, echocardiographic parameters of left ventricular function and prostacyclin-thromboxane balance. In angina pectoris, the lower rate of cerebral blood flow was found to be correlated with the integral parameter of myocardial ischemia, deteriorated cardiac contractile and pump function, and higher plasma thromboxane A2 levels.

[An evaluation of the hypolipidemic effects of lovastatin in primary hypercholesterolemia. A multicenter study].

In the multicenter trial, the hypolipidemic efficacy and adverse event profile of lovastatin were estimated in 294 patients with primary hypercholesterolemia. The mean baseline (on placebo) lipid and lipoprotein values were: total serum cholesterol (TC) 313 mg/dl, triglycerides (TG) 168 mg/dl, low density lipoprotein cholesterol (LDL-C) 235 mg/dl, high density lipoprotein cholesterol (HDL-C) 44.9 mg/dl.