First-principles study of the crystal structures and physical properties of H₁₈-BN and Rh6-BN

Ren, X.Y.,Zhao, C.X.,Niu, C.Y.,Wang, J.Q.,Jia, Y.,Cho, J.H. North-Holland 2016 Physics letters. Section A. Vol.380 No.46

<P>As the analog of carbon allotropes, new three-dimensional (3D) boron nitride (BN) allotropes have attracted much attention of researchers due to their great importance in fundamental sciences and wide practical applications. Here, based on first-principles density-functional theory calculations, we predict two new stable BN allotropes: One is H-18-BN with the P (6) over bar m2 (D-3h(1)) symmetry containing eighteen atoms in the hexagonal unit cell and the other is Rh6-BN with the R (3) over barm (C-3v(5)) symmetry containing six atoms in the rhombohedral primitive unit cell. The dynamic stabilities of the two structures are examined through the phonon spectrum analysis as well as molecular dynamics simulations, whereas the mechanical properties are analyzed by elastic constants, bulk modulus and shear modulus. From the analysis of the enthalpy evolution with respect to pressure, we find that h-BN can be transformed into either H-18-BN or RH6-BN structure under a higher pressure of similar to 15 GPa. We also find that both the H-18-BN and Rh6-BN allotropes are brittle materials with indirect band gaps of 2.31 and 4.48 eV, respectively. The simulated XRD spectra provide detailed structural information of H-18-BN and Rh6-BN for future experimental examinations. Our findings not only greatly enrich the existing structural family of 3D-BN materials but also stimulate further experiments. (C) 2016 Elsevier B.V. All rights reserved.</P>

Right-sided acute diverticulitis in the West: experience at a university hospital in Argentina

Huatuco René M. Palacios,Pachajoa Diana A. Pantoja,Liaño Julian E.,Molina Héctor A. Picón,Palencia Rafael,Doniquian Alejandro M.,Parodi Matías 대한대장항문학회 2023 Annals of Coloproctolgy Vol.39 No.2

Purpose: In the West, diverticular disease is located mainly in the left colon. However, it can also present in the right colon, with an incidence of 1%–2% in Caucasians. The purpose of this study was to describe our experience in right-sided acute diverticulitis (RD). Methods: In this retrospective study, 410 patients with acute diverticulitis treated from 2013 to 2020 were included in a university hospital in Córdoba, Argentina. Colonic diverticulitis was stratified into 2 groups; RD and left-sided acute diverticulitis. Demographic and clinical variables, laboratory and imaging findings, type of treatment, follow-up, and recurrence were analyzed. Results: Sixteen patients (3.9%) with RD were identified; 62.5% were male and the mean age was 40.7±11.7 years. A total of 81.3% were Caucasian and 18.7% Native American. Significant differences were found between both groups of diverticulitis; patients with RD were younger (P=0.001), with lower BMI (P=0.01), comorbidity rate (P=0.01), Charlson comorbidity index (P=0.02), hospital stay (P=0.01), severity according to the Hinchey classification (P=0.001) and had a lower recurrence rate (P=0.001). There were no significant differences in sex (P=0.95), duration of pain until admission (P=0.05), laboratory findings (P=0.23) and treatment (P=0.34). Conclusion: Conservative treatment predominated in RD, with a lower rate of complications and recurrences, providing data that support conservative therapy as initial treatment in RD in our environment.

Robot assisted surgery during the COVID-19 pandemic, especially for gynecological cancer: a statement of the Society of European Robotic Gynaecological Surgery (SERGS)

Rainer Kimmig,René H.M. Verheijen,Martin Rudnicki,SERGS Council 대한부인종양학회 2020 Journal of Gynecologic Oncology Vol.31 No.3

All surgery performed in an epicenter of the coronavirus disease 2019 (COVID-19) pandemic, irrespective of the known or suspected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) status of the patient, should be regarded as high risk and protection of the surgical team at the bedside should be at the highest level. Robot assisted surgery (RAS) may help to reduce hospital stay for patients that urgently need complex-oncological-surgery, thus making room for COVID-19 patients. In comparison to open or conventional laparoscopic surgery, RAS potentially reduces not only contamination with body fluids and surgical gasses of the surgical area but also the number of directly exposed medical staff. A prerequisite is that general surgical precautions under COVID-19 circumstances must be taken, with the addition of prevention of gas leakage:• Use highest protection level III for bedside assistant, but level II for console surgeon. • Reduce the number of staff at the operation room. • Ensure safe and effective gas evacuation. • Reduce the intra-abdominal pressure to 8 mmHg or below. • Minimize electrocautery power and avoid use of ultrasonic sealing devices. • Surgeons should avoid contact outside theater (both in and out of the hospital).

Casting light on the overlooked trigger point of the interosseous muscles in metatarsalgia: insights and treatment strategies

Bülent Alyanak,Burak Tayyip Dede,Mustafa Hüseyin Temel,Mustafa Turgut Yıldızgören,Fatih Bağcıer 대한초음파의학회 2024 ULTRASONOGRAPHY Vol.43 No.4

The Neurochemical Effects of Prazosin Treatment on Fear Circuitry in a Rat Traumatic Stress Model

Sema Ketenci,Nazife Gökçe Acet,Gökçe Elif Sarıdoğan,Banu Aydın,Hülya Cabadak,Mehmet Zafer Gören 대한정신약물학회 2020 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.18 No.2

Objective: The timing of administration of pharmacologic agents is crucial in traumatic stress since they can either potentiate the original fear memory or may cause fear extinction depending on the phase of fear conditioning. Brain noradrenergic system has a role in fear conditioning. Data regarding the role of prazosin in traumatic stress are controversial. Methods: In this study, we examined the effects of prazosin and the noradrenergic system in fear conditioning in a predator stress rat model. We evaluated the direct or indirect effects of stress and prazosin on noradrenaline (NA), gamma-aminobuytyric acid (GABA), glutamate, glycine levels and choline esterase activity in the amygdaloid complex, the dorsal hippocampus, the prefrontal cortex and the rostral pons. Results: Our results demonstrated that prazosin might alleviate defensive behaviors and traumatic stress symptoms when given during the traumatic cue presentation in the stressed rats. However prazosin administration resulted in higher anxiety levels in non stressed rats when the neutral cue was presented. Conclusion: Prazosin should be used in PTSD with caution because prazosin might exacerbate anxiety in non-traumatized subjects. However prazosin might as well alleviate stress responses very effectively. Stress induced changes included increased NA and GABA levels in the amygdaloid complex in our study, attributing noradrenaline a possible inhibitory role on fear acquisition. Acetylcholine also has a role in memory modulation in the brain. We also demonstrated increased choline esterase acitivity. Cholinergic modulation might be another target for indirect prazosin action which needs to be further studied.

Whole ceramic-like microreactors from inorganic polymers for high temperature or/and high pressure chemical syntheses

Ren, W.,Perumal, J.,Wang, J.,Wang, H.,Sharma, S.,Kim, D. P. Royal Society of Chemistry 2014 Lab on a chip Vol.14 No.4

Two types of whole ceramic-like microreactors were fabricated from inorganic polymers, polysilsesquioxane (POSS) and polyvinylsilazane (PVSZ), that were embedded with either perfluoroalkoxy (PFA) tube or polystyrene (PS) film templates, and subsequently the templates were removed by physical removal (PFA tube) or thermal decomposition (PS). A POSS derived ceramic-like microreactor with a 10 cm long serpentine channel was obtained by an additional 'selective blocking of microchannel' step and subsequent annealing at 300 degrees C for 1 h, while a PVSZ derived ceramic-like microreactor with a 14 cm long channel was yielded by a co-firing process of the PVSZ-PS composite at 500 degrees C for 2 h that led to complete decomposition of the film template leaving a microchannel behind. The obtained whole ceramic-like microfluidic devices revealed excellent chemical and thermal stabilities in various solvents, and they were able to demonstrate unique chemical performance at high temperature or/and high pressure conditions such as Michaelis-Arbuzov rearrangement at 150-170 degrees C, Wolff-Kishner reduction at 200 degrees C, synthesis of super-paramagnetic Fe3O4 nanoparticles at 320 degrees C and isomerisation of allyloxybenzene to 2-allylphenol (250 degrees C and 400 psi). These economic ceramic-like microreactors fabricated by a facile non-lithographic method displayed excellent utility under challenging conditions that is superior to any plastic microreactors and comparable to glass and metal microreactors with high cost.

Evaluation of Ni Film Interfacial Energy Release Rate on Titanium and Stainless Steel Substrates

Ren, F. Z.,Zhao, W. Z.,Zhou, G. S.,Ju, X. H.,Zheng, M. 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.2

An expression including the effect of residual stress on the interfacial energy release rate is proposed for peeling experiments according to the energy-balance argument. The influence of residual stress on the external work is also contained in the expression. Two numerical methods are employed to evaluate the values of the work expenditure G_db, which is the actual energy dissipated during bending of the peel arm near the peel front. The peeling method is employed to test the interfacial energy release rates, G, for Ni films on Titanium and stainless steel substrates. The results indicate that the value of G for Ni films on stainless steel substrate is about 5.47-6.03 N/m, while 5.23-6.71 N/m for Ni films on titanium substrate; the interfacial energy release rates, G, do not depend on the residual stress in film, film thickness nor peel angle. The effect of residual stress in film on peel strength P/h is also discussed.

Eddy-Induced Growth Rate of Low-Frequency Variability and Its Mid- to Late Winter Suppression in the Northern Hemisphere

Ren, H.-L.,Jin, F.-F.,Kug, J.-S. AMERICAN METEOROLOGICAL SOCIETY 2014 Journal of the atmospheric sciences Vol.71 No.7

Synoptic eddy and low-frequency flow (SELF) feedback plays an important role in reinforcing low-frequency variability (LFV). Recent studies showed that an eddy-induced growth (EIG) or instability makes a fundamental contribution to the maintenance of LFV. To quantify the efficiency of the SELF feedback, this study examines the spatiotemporal features of the empirical diagnostics of EIG and its associations with LFV. The results show that, in terms of eddy vorticity forcing, the EIG rate of LFV is generally larger (smaller) in the upper (lower) troposphere, whereas, in terms of eddy potential vorticity forcing, it is larger in the lower troposphere to partly balance the damping effect of surface friction. The local EIG rate shows a horizontal spatial distribution that corresponds to storm-track activity, which tends to be responsible for maintaining LFV amplitudes and patterns as well as sustaining eddy-driven jets. In fact, the EIG rate has a well-defined seasonality, being generally larger in cold seasons and smaller in the warmest season, and this seasonality is stronger in the Northern Hemisphere than in the Southern Hemisphere. This study also reveals a mid-to late winter (January-March) suppression of the EIG rate in the Northern Hemisphere, which indicates a reduced eddy feedback efficiency and may be largely attributed to the eddy kinetic energy suppression and the midlatitude zonal wind maximum in the midwinter of the Northern Hemisphere.

A penny-shaped interfacial crack between piezoelectric layer and elastic half-space

Ren, J.H.,Li, Y.S.,Wang, W. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.1

An interfacial penny-shaped crack between piezoelectric layer and elastic half-space subjected to mechanical and electric loads is investigated. Using Hankel transform technique, the mixed boundary value problem is reduced to a system of singular integral equations. The integral equations are further reduced to a system of algebraic equations with the aid of Jacobi polynomials. The stress intensity factor and energy release rate are determined. Numerical results reveal the effects of electric loadings and material parameters of composite on crack propagation and growth. The results seem useful for design of the piezoelectric composite structures and devices of high performance.

Compost Extract and Organic Manure Improve the Plant Growth of Lucerne (Medicago sativa) and Soil Properties Synergistically by Helping in the Nodulation Process

H. Y. Ren,G. D. Han,Z. N. Nie,G. W. Yang,J. Schrautzer,Y. J. Zhang 한국초지조사료학회 2016 한국초지조사료학회 학술대회논문집 Vol.2016 No.08