Hepatitis E virus in pigs and the environment: An updated review of public health concerns.

Hepatitis E virus (HEV) is an important public health problem and is responsible for both acute and chronic viral hepatitis. Public health implications of HEV are derived from its transmission route, either water-borne or food-borne, and its zoonotic potential. Not only in developing countries, but HEV cases are also found in a high number in developed countries. The spread of HEV to the environment might pollute surface waters, which could act as the source of infection for both humans and animals. Identification of the virus in animal products suggests the circulation of HEV within water and food chains. High seroprevalence and circulation of HEV in livestock, in particular pigs, as well as in environmental samples warrants further investigation into pig markets. HEV virulence in different environments and meat supply chains could shed light on the possible sources of infection in humans and the degree of occupational risk. The purpose of this review is to discuss HEV infections with an emphasis on livestock- and environment-related risk factors, and food-borne, water-borne, and zoonotic transmissions.

Fluid mechanics of facial masks as personal protection equipment (PPE) of COVID-19 virus.

A fluid mechanics model of inhaled air gases, nitrogen (N2) and oxygen (O2) gases, and exhaled gas components (CO2 and water vapor particles) through a facial mask (membrane) to shield the COVID-19 virus is established. The model was developed based on several gas flux contributions that normally take place through membranes. Semiempirical solutions of the mathematical model were predicted for the N95 facial mask accounting on several parameters, such as a range of porosity size (i.e., 1-30 nm), void fraction (i.e., 10-3%-0.3%), and thickness of the membrane (i.e., 10-40 µm) in comparison to the size of the COVID-19 virus. A unitless number (Nr) was introduced for the first time to describe semiempirical solutions of O2, N2, and CO2 gases through the porous membrane. An optimum Nr of expressing the flow of the inhaled air gases, O2 and N2, through the porous membrane was determined (NO2 = NN2 = -4.4) when an N95 facial mask of specifications of a = 20 nm, l = 30 µm, and ε = 30% was used as a personal protection equipment (PPE). The concept of the optimum number Nr can be standardized not only for testing commercially available facial masks as PPEs but also for designing new masks for protecting humans from the COVID-19 virus.

Graphene transistor based on tunable Dirac fermion optics.

We present a quantum switch based on analogous Dirac fermion optics (DFO), in which the angle dependence of Klein tunneling is explicitly utilized to build tunable collimators and reflectors for the quantum wave function of Dirac fermions. We employ a dual-source design with a single flat reflector, which minimizes diffusive edge scattering and suppresses the background incoherent transmission. Our gate-tunable collimator-reflector device design enables the quantitative measurement of the net DFO contribution in the switching device operation. We obtain a full set of transmission coefficients between multiple leads of the device, separating the classical contribution from the coherent transport contribution. The DFO behavior demonstrated in this work requires no explicit energy gap. We demonstrate its robustness against thermal fluctuations up to 230 K and large bias current density up to 102 A/m, over a wide range of carrier densities. The characterizable and tunable optical components (collimator-reflector) coupled with the conjugated source electrodes developed in this work provide essential building blocks toward more advanced DFO circuits such as quantum interferometers. The capability of building optical circuit analogies at a microscopic scale with highly tunable electron wavelength paves a path toward highly integrated and electrically tunable electron-optical components and circuits.

Atomic-Scale Characterization of Graphene p-n Junctions for Electron-Optical Applications.

Graphene p-n junctions offer a potentially powerful approach toward controlling electron trajectories via collimation and focusing in ballistic solid-state devices. The ability of p-n junctions to control electron trajectories depends crucially on the doping profile and roughness of the junction. Here, we use four-probe scanning tunneling microscopy and spectroscopy (STM/STS) to characterize two state-of-the-art graphene p-n junction geometries at the atomic scale, one with CMOS polySi gates and another with naturally cleaved graphite gates. Using spectroscopic imaging, we characterize the local doping profile across and along the p-n junctions. We find that realistic junctions exhibit non-ideality both in their geometry as well as in the doping profile across the junction. We show that the geometry of the junction can be improved by using the cleaved edge of van der Waals metals such as graphite to define the junction. We quantify the geometric roughness and doping profiles of junctions experimentally and use these parameters in non-equilibrium Green's function-based simulations of focusing and collimation in these realistic junctions. We find that for realizing Veselago focusing, it is crucial to minimize lateral interface roughness which only natural graphite gates achieve and to reduce junction width, in which both devices under investigation underperform. We also find that carrier collimation is currently limited by the non-linearity of the doping profile across the junction. Our work provides benchmarks of the current graphene p-n junction quality and provides guidance for future improvements.

Amantadine for the Treatment of Refractory Absence Seizures in Children.

INTRODUCTION: Childhood epilepsy is a generalized epilepsy syndrome with a favorable response to antiepileptic drugs; however, a small percentage of typical absence seizures remain refractory to drugs. We studied the safety and efficacy of amantadine in children with refractory absence seizures. MATERIALS AND METHODS: Of 48 children with typical absence seizures attending the outpatient department of a tertiary care neurological center over a period of 3 years from July 2013 to June 2016, 4 children who were refractory to standard treatment for at least 1 year were selected and were started on amantadine 4-6 mg/kg/day, after obtaining informed consent. OBSERVATIONS: The children, aged between 7 and 14 years, had more than 10 episodes of seizures per day in spite of polytherapy with valproate, lamotrigine, clonazepam, levetiracetam, and topiramate in various combinations. Electrographically, all showed the typical generalized 3 Hz spike wave discharges activated by hyperventilation. All the children became seizure free within 1 week after starting amantadine, and there was improvement in their school performance. The children continue to remain seizure free for 6-30 months now. No significant adverse effects were observed on addition of amantadine. DISCUSSION: Amantadine can be tried as a safe add-on drug for children with absence epilepsy refractory to multiple drugs. Further multicenter trials may be needed to prove its effectiveness, as the numbers are small.

Graphene Klein tunnel transistors for high speed analog RF applications.

We propose Graphene Klein tunnel transistors (GKTFET) as a way to enforce current saturation while maintaining large mobility for high speed radio frequency (RF) applications. The GKTFET consists of a sequence of angled graphene p-n junctions (GPNJs). Klein tunneling creates a collimation of electrons across each GPNJ, so that the lack of substantial overlap between transmission lobes across successive junctions creates a gate-tunable transport gap without significantly compromising the on-current. Electron scattering at the device edge tends to bleed parasitic states into the gap, but the resulting pseudogap is still sufficient to create a saturated output (I D -V D ) characteristic and a high output resistance. The modulated density of states generates a higher transconductance (g m ) and unity current gain cut-off frequency (f T ) than GFETs. More significantly the high output resistance makes the unity power gain cut-off frequency (f max ) of GKTFETs considerably larger than GFETs, making analog GKTFET potentially useful for RF electronics. Our estimation shows the f T /f max of a GKTFET with 1 µm channel reaches 33 GHz/17 GHz, and scale up to 350 GHz/53 GHz for 100 nm channel (assuming a single, scalable trapezoidal gate). The f max of a GKTFET is 10 times higher than a GFET with the same channel length.

Electron optics with p-n junctions in ballistic graphene.

Electrons transmitted across a ballistic semiconductor junction are expected to undergo refraction, analogous to light rays across an optical boundary. In graphene, the linear dispersion and zero-gap band structure admit highly transparent p-n junctions by simple electrostatic gating. Here, we employ transverse magnetic focusing to probe the propagation of carriers across an electrostatically defined graphene junction. We find agreement with the predicted Snell's law for electrons, including the observation of both positive and negative refraction. Resonant transmission across the p-n junction provides a direct measurement of the angle-dependent transmission coefficient. Comparing experimental data with simulations reveals the crucial role played by the effective junction width, providing guidance for future device design. Our results pave the way for realizing electron optics based on graphene p-n junctions.

Opto-electrochemical spectroscopy of metals in aqueous solutions.

In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance-emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%-2.5% H2SO4) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H2SO4 solutions. The electrical resistance-emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.

Cost implications and oncological outcomes for laparoscopic versus open surgery for right hemicolectomy.

INTRODUCTION: Recent studies have suggested that laparoscopic surgery for colorectal resection confers a cost benefit compared with open surgery. These studies have considered a wide range of colorectal operations together rather than focusing on a single procedure. Our study compared direct clinical costs for laparoscopic versus open right hemicolectomy. METHODS: Clinicopathological data and cost of treatment for all patients who underwent a right hemicolectomy between 2012 and 2013 were collected. The primary outcome was total cost of treatment. Secondary outcomes were length of stay, operative time and morbidity. The minimum follow-up duration was 12 months. Costs for laparoscopic and open surgery for elective resection alone were compared. Further analyses were performed comparing emergency cases with elective cases and cancer with non-cancer cases. RESULTS: There were 83 patients who underwent a right hemicolectomy during the study period and of these, 65 had an elective procedure. The total cost of a laparoscopic procedure was £3,998.12 compared with £3,427.50 for open surgery (p=0.039). The length of stay was shorter for laparoscopic surgery while the cost of an emergency right hemicolectomy was significantly greater than for elective surgery. CONCLUSIONS: Although the length of stay for laparoscopic surgery was shorter, this did not translate to a reduction in cost. The cost benefit from a shorter length of stay was offset by a greater cost of consumables. Cost effectiveness analyses should be designed carefully, and they should consider individual operations separately when making healthcare management and funding decisions.

Chiral tunneling of topological states: towards the efficient generation of spin current using spin-momentum locking.

We show that the interplay between chiral tunneling and spin-momentum locking of helical surface states leads to spin amplification and filtering in a 3D topological insulator (TI). Our calculations show that the chiral tunneling across a TI pn junction allows normally incident electrons to transmit, while the rest are reflected with their spins flipped due to spin-momentum locking. The net result is that the spin current is enhanced while the dissipative charge current is simultaneously suppressed, leading to an extremely large, gate-tunable spin-to-charge current ratio (∼20) at the reflected end. At the transmitted end, the ratio stays close to 1 and the electrons are completely spin polarized.

Utility of contrast enema to assess anastomotic integrity and the natural history of radiological leaks after low rectal surgery: systematic review and meta-analysis.

PURPOSE: There is no clear consensus on how to assess low rectal anastomotic integrity and patency prior to reversal of de-functioning stoma. The aim of this systematic review was to assess the utility of contrast enema (CE) in this context and to clarify the natural history of radiological leaks. METHODS: Keyword search of electronic databases (Embase, MEDLINE, Cochrane Library, Google Scholar) and bibliographic cross-referencing were performed to identify appropriate studies. Data extraction and synthesis was performed with the primary outcomes being the sensitivity and specificity of CE for detecting clinically significant abnormalities. Statistical analysis was performed using Open Meta-Analyst software. Narrative review of outcomes including those of clinical and radiological leaks was also undertaken. RESULTS: A total of 1,142 CE from 11 articles were included in the final meta-analysis. CE had high specificity (95.4; 95 % confidence interval = 92.0-97.4) and negative predictive value (98.4; 97.4-99.1) and moderate sensitivity (79.9; 63.9-89.9) and positive predictive value (64.6; 55.5-72.9) for the detection of clinically significant anastomotic problems. There was a high degree of correlation between CE and clinical examination findings (96.7 %). Occult radiological leaks were seen in 5.7 % of CE, and all but one (97 %) eventually underwent successful reversal. Only three quarters of patients with clinical leak underwent successful reversal. CONCLUSION: CE is effective at excluding clinically significant anastomotic problems, especially after clinical anastomotic leaks. However, false positive results can be observed in asymptomatic patients, and it is unclear how much additional information CE provides over clinical assessment in the low uncomplicated anastomosis.

Degradation/oxidation susceptibility of organic photovoltaic cells in aqueous solutions.

A criterion of the degradation/oxidation susceptibility of organic photovoltaic (OPV) cells in aqueous solutions was proposed for the first time. The criterion was derived based on calculating the limit of the ratio value of the polarization resistance of an OPV cell in aqueous solution (Rp(s)) to the polarization resistance of the OPV cell in air (Rp(air)). In other words, the criterion lim(Rp(s)/Rp(air)) = 1 was applied to determine the degradation/oxidation of the OPV cell in the aqueous solution when Rp(air) became equal (increased) to Rp(s) as a function of time of the exposure of the OPV cell to the aqueous solution. This criterion was not only used to determine the degradation/oxidation of different OPV cells in a simulated operational environment but also it was used to determine the electrochemical behavior of OPV cells in deionized water and a polluted water with fine particles of sand. The values of Rp(s) were determined by the electrochemical impedance spectroscopy at low frequency. In addition, the criterion can be applied under diverse test conditions with a predetermined period of OPV operations.

Uterus and extralevator abdominoperineal excision: a technique.

BACKGROUND: Perineal hernia is well described after standard abdominoperineal excision of rectum. There appears to be an increasing incidence of perineal hernia following extralevator abdominoperineal excision of the rectum. Currently, there is no standard for the prevention of perineal wound herniation and its potential sequelae. Techniques have been described to prevent perineal hernia, including the use of mesh, muscle flaps, or simple layered closure. OBJECTIVE: This technique describes the use of the uterus in postmenopausal women as a "natural packing material" to prevent the small bowel from entering the lower pelvis, and subsequent perineal herniation. PROCEDURE: The procedure involves retroverting the uterus and securing it to the bony pelvis with the use of nonabsorbable suture material. This can be achieved via the abdominal route as well as the perineal wound. LIMITATIONS: This procedure is only applicable in women with uterus in situ. Dyspareunia may be a side effect. Caution is advised in premenopausal women, because positional menstruation may be an issue. Subsequent hysteroscopy and hysterectomy may be difficult. Care should be taken to avoid damage to the presacral venous plexus and sacral nerves. CONCLUSION: Uterine interposition is a practical, low-risk, inexpensive solution to this problem in a selected group of patients. It avoids the cost and complications of prosthetic mesh and myoplastic reconstruction procedures.

In-hospital complications and 1-year outcome of acute coronary syndrome in patients with hypertension: findings from the 2nd Gulf Registry of Acute Cardiac Events.

Using data from the 2nd Gulf Registry of Acute Coronary Events (Gulf RACE-2) in 2008-09 we investigated the in-hospital complications and 1-year outcome of acute coronary syndrome (ACS) in patients with systemic hypertension from 6 Gulf countries. Of 7847 consecutive patients admitted with ACS, 3746 (47.7%) had hypertension. Hypertension was more prevalent in women, in Arabs than non-Arabs and in older age groups. Patients with hypertension were more likely than those without hypertension to present with dyspnoea and advanced Killip class. Among hypertensive patients, the mortality rate was higher only among those admitted with ST-elevation myocardial infarction. After adjustment for baseline variables, hypertension was an independent predictive factor for heart failure (OR = 1.31) and stroke (OR = 2.47). here were no significant differences in mortality in hypertensive ACS patients when stratified by sex, age or ethnicity.

In-hospital complications and 1-year outcome of acute coronary syndrome in patients with hypertension: findings from the 2nd Gulf registry of acute cardiac events

Using data from the 2nd Gulf Registry of Acute Coronary Events [Gulf RACE-2] in 2008-09 we investigated the in-hospital complications and 1-year outcome of acute coronary syndrome [ACS] in patients with systemic hypertension from 6 Gulf countries. Of 7847 consecutive patients admitted with ACS, 3746 [47.7%] had hypertension. Hypertension was more prevalent in women, in Arabs than non-Arabs and in older age groups. Patients with hypertension were more likely than those without hypertension to present with dyspnoea and advanced Killip class. Among hypertensive patients, the mortality rate was higher only among those admitted with ST-elevation myocardial infarction. After adjustment for baseline variables, hypertension was an independent predictive factor for heart failure [OR = 1.31] and stroke [OR = 2.47]. There were no significant differences in mortality in hypertensive ACS patients when stratified by sex, age or ethnicity

Acute coronary syndrome and khat herbal amphetamine use: an observational report.

BACKGROUND: The khat plant is a stimulant similar to amphetamine and is thought to induce coronary artery spasm. Khat is widely chewed by individuals originating from the Horn of Africa and the Arabian Peninsula. The aim of this study was to evaluate the clinical characteristics and outcome of khat chewers presenting with acute coronary syndrome. METHODS AND RESULTS: From October 1, 2008, through June, 30, 2009, 7399 consecutive patients with acute coronary syndrome were enrolled in the Second Gulf Registry of Acute Coronary Events (Gulf RACE-2). Nineteen percent of patients were khat chewers; 81% were not. Khat chewers were older, more often male, and less likely to have cardiovascular risk factors. Khat chewers were less likely to have a history of coronary artery disease and more likely to present late and to have higher heart rate and advanced Killip class on admission. Khat chewers were more likely to present with ST-segment-elevation myocardial infarction. Overall, khat chewers had higher risk of death, recurrent myocardial ischemia, cardiogenic shock, ventricular arrhythmia, and stroke compared with non-khat chewers. After adjustment for baseline variability, khat chewing was found to be an independent risk factor of death and for recurrent ischemia, heart failure, and stroke. CONCLUSIONS: Our data confirm earlier observations of worse in-hospital outcome among acute coronary syndrome patients who chew khat. This worse outcome persists up to 1 year from the index event. This observational report underscores the importance of improving education concerning the cardiovascular risks of khat chewing.

Permanent electric dipole moments of carboxyamides in condensed media: what are the limitations of theory and experiment?

Electrostatic properties of proteins are crucial for their functionality. Carboxyamides are small polar groups that, as peptide bonds, are principal structural components of proteins that govern their electrostatic properties. We investigated the medium dependence of the molar polarization and of the permanent dipole moments of amides with different state of alkylation. The experimentally measured and theoretically calculated dipole moments manifested a solvent dependence that increased with the increase in the media polarity. We ascribed the observed enhancement of the amide polarization to the reaction fields in the solvated cavities. Chloroform, for example, caused about a 25% increase in the amide dipole moments determined for vacuum, as the experimental and theoretical results demonstrated. Another chlorinated solvent, 1,1,2,2-tetrachloroethane, however, caused an "abnormal" increase in the experimentally measured amide dipoles, which the theoretical approaches we used could not readily quantify. We showed and discussed alternatives for addressing such discrepancies between theory and experiment.