Ab initio prediction of semiconductivity in a novel two-dimensional Sb2X3 (X= S, Se, Te) monolayers with orthorhombic structure.

[Formula: see text] and [Formula: see text] are well-known layered bulk structures with weak van der Waals interactions. In this work we explore the atomic lattice, dynamical stability, electronic and optical properties of [Formula: see text], [Formula: see text] and [Formula: see text] monolayers using the density functional theory simulations. Molecular dynamics and phonon dispersion results show the desirable thermal and dynamical stability of studied nanosheets. On the basis of HSE06 and PBE/GGA functionals, we show that all the considered novel monolayers are semiconductors. Using the HSE06 functional the electronic bandgap of [Formula: see text], [Formula: see text] and [Formula: see text] monolayers are predicted to be 2.15, 1.35 and 1.37 eV, respectively. Optical simulations show that the first absorption coefficient peak for [Formula: see text], [Formula: see text] and [Formula: see text] monolayers along in-plane polarization is suitable for the absorption of the visible and IR range of light. Interestingly, optically anisotropic character along planar directions can be desirable for polarization-sensitive photodetectors. Furthermore, we systematically investigate the electrical transport properties with combined first-principles and Boltzmann transport theory calculations. At optimal doping concentration, we found the considerable larger power factor values of 2.69, 4.91, and 5.45 for hole-doped [Formula: see text], [Formula: see text], and [Formula: see text], respectively. This study highlights the bright prospect for the application of [Formula: see text], [Formula: see text] and [Formula: see text] nanosheets in novel electronic, optical and energy conversion systems.

Two-dimensional carbon nitride C6N nanosheet with egg-comb-like structure and electronic properties of a semimetal.

In this study, the structural, electronic and optical properties of theoretically predicted C6N monolayer structure are investigated by means of Density Functional Theory-based First-Principles Calculations. Phonon band dispersion calculations and molecular dynamics simulations reveal the dynamical and thermal stability of the C6N single-layer structure. We found out that the C6N monolayer has large negative in-plane Poisson's ratios along bothXandYdirection and the both values are almost four times that of the famous-pentagraphene. The electronic structure shows that C6N monolayer is a semi-metal and has a Dirac-point in the BZ. The optical analysis using the random phase approximation method constructed over HSE06 illustrates that the first peak of absorption coefficient of the C6N monolayer along all polarizations is located in theIRrange of spectrum, while the second absorption peak occurs in the visible range, which suggests its potential applications in optical and electronic devices. Interestingly, optically anisotropic character of this system is highly desirable for the design of polarization-sensitive photodetectors. Thermoelectric properties such as Seebeck coefficient, electrical conductivity, electronic thermal conductivity and power factor are investigated as a function of carrier doping at temperatures 300, 400, and 500 K. In general, we predict that the C6N monolayer could be a new platform for study of novel physical properties in two-dimensional semi-metal materials, which may provide new opportunities to realize high-speed low-dissipation devices.

On how differently the quasi-harmonic approximation works for two isostructural crystals: thermal properties of periclase and lime.

Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, α(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, CV(T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, CP(T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer.

Clinical evaluation of repeated propofol total intravenous anesthesia in dog.

This current study designed to evaluate any possible changes in required doses and other cardiopulmonary findings after repeated propofol total intravenous anesthesia (TIVA) in dog. The study was conducted in 6 healthy sheepdogs, weight between 16.5 and 28 kg. Anaesthesia induced by 8 mg kg(-1) of propofol and maintained by continuous propofol (0.3 mg/kg/min) infusion in saline solution. All dogs received three times of propofol anaesthesia with the same protocol in a cross over design. As the animals in first, second and third time of anaesthesia allocated into groups 1, 2 and 3, respectively. Heart Rate (HR), rectal temperature (Temp), blood oxygen saturation (SpO2) by pulse oximetry and non invasive arterial blood pressures were measured. Times to the first swallowing attempt, ability to lift the head and standing were measured during recovery. The apnea was recorded in all animals but no significant difference was recorded between groups under study. Calculated doses of induction were sufficient for intubation of the animals. The average doses foe maintenance of anesthesia did not show any significant difference between groups under study. There were no significant differences found between groups in any comparable parameter. Despite of longer recovery time in group three, there were no significant differences between the Groups in different recovery times. Repeated propofol anesthesia did not improve resistance and respiratory changes in this species. However, some effects on blood pressure may happen without any effect on heart rate.

An anatomic study of the lingual nerve in the third molar region.

PURPOSE: The aim of this study was to determine the location of the lingual nerve in the lower third molar region. PATIENTS AND METHODS: In this study, 669 nerves from 430 fresh cadavers were examined. Measurements on each cadaver were made using a micrometer caliper to determine the horizontal and vertical position of the lingual nerve in the lower third molar region. RESULTS: In 94 cases (14.05%), the nerve was above the lingual crest, and in 1 case (0.15%), the nerve was in the retromolar pad region. In the remaining 574 cases (85.80%), the mean horizontal and vertical distances of the nerve to the lingual plate and the lingual crest 2.06 +/- 1.10 mm (range, 0.00 to 3.20 mm) and 3.01 +/- 0.42 mm (range, 1.70 to 4.00 mm), respectively. In 149 cases (22.27%), the nerve was in direct contact with the lingual plate of the alveolar process. CONCLUSIONS: This study confirms the relatively unsafe position of the lingual nerve in relation to some oral and maxillofacial surgery procedures.

The effects of lithium, indomethacin, and neomycin on vasopressin-induced contractions in rat urinary bladder.

1. [Arg8]Vasopressin (AVP) induced a contraction response in rat urinary bladder smooth muscle in a dose-dependent manner. 2. Indomethacin in a 10-microM concentration cannot change the effects of AVP on urinary bladder smooth muscle, which seem to be mediated by a direct action on the muscle rather than indirectly through prostanoid release. 3. Lithium (0.5, 1, and 10 mM) made the muscle more sensitive to AVP action. 4. Neomycin (1.25, 2.5, and 5 mM) had an inhibitory effect on AVP-induced contraction. 5. It seems that in rat urinary bladder vasopressin-induced contraction is mediated through phosphoinositide metabolism.