Tunable Spin-Polarized Edge Currents in Proximitized Transition Metal Dichalcogenides.

We explore proximity-induced ferromagnetism on transition metal dichalcogenides (TMDs), focusing on molybdenum ditelluride ribbons with zigzag edges, deposited on ferromagnetic europium oxide (EuO). A tight-binding model incorporates exchange and Rashba fields induced by proximity to EuO or similar substrates. For in-gap Fermi levels, electronic modes in the nanoribbon are localized along the edges, acting as one-dimensional (1D) conducting channels with tunable spin-polarized currents. TMDs on magnetic substrates can become very useful in spintronics, providing versatile platforms to study the proximity effects and electronic interactions in complex 1D systems.

Satellite DNA methylation status and expression of selected genes in Bos indicus blastocysts produced in vivo and in vitro.

Bovine embryos produced in vivo and in vitro differ with respect to molecular profiles, including epigenetic marks and gene expression profiles. This study investigated the CpG methylation status in bovine testis satellite I (BTS) and Bos taurus alpha satellite I (BTαS) DNA sequences, and concomitantly the relative abundance of transcripts, critically involved in DNA methylation (DNMT1 and DNMT3A), growth and development (IGF2R) and pluripotency (POU5F1) in Bos indicus embryos produced in vitro or in vivo. Results revealed that methylation of BTS were higher (P < 0.05) in embryos produced in vitro compared with their in vivo produced counterparts, while the methylation status of BTαS was similar in both groups. There were no significant differences in transcript abundance for DNMT3A, IGF2R and POU5F1 between blastocysts produced in vivo and in vitro. However, a significantly lower amount of DNMT1 transcripts was found in the in vitro cultured embryos (P < 0.05) compared with their in vivo derived counterparts. In conclusion, this study reported only minor changes in the expression of developmentally important genes and satellite DNA methylation related to the in vitro embryo production system.

A report on the outbreak of Zika virus on Easter Island, South Pacific, 2014.

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus circulating in Asia and Africa. In 2013, a large outbreak was reported on the archipelago of French Polynesia. In this study, we report the detection and molecular characterization of Zika virus for the first time in Chile from an outbreak among the inhabitants of Easter Island. A total of 89 samples from patients suspected of having ZIKV infection were collected between the period from January to May, 2014. Molecular diagnosis of the virus was performed by RT-PCR followed by the sequencing of the region containing the NS5 gene. A comparison of the viral nucleic acid sequence with those of other strains of ZIKA virus was performed using the MEGA software. Fifty-one samples were found positive for ZIKV by RT-PCR analysis. Further analysis of the NS5 gene revealed that the ZIKV strains identified in Easter Island were most closely related to those found in French Polynesia (99.8 to 99.9% nt and 100% aa sequence identity). These results strongly suggest that the transmission pathway leading to the introduction of Zika virus on Easter Island has its origin in French Polynesia.

Rapid spread of Clostridium difficile NAP1/027/ST1 in Chile confirms the emergence of the epidemic strain in Latin America.

Clostridium difficile infection has gained importance in recent years as a result of the rapid spread of epidemic strains, including hypervirulent strains. This study reports the molecular epidemiology of C. difficile obtained from hospitalized patients in Chile. Seven hundred and nineteen isolates of toxigenic C. difficile from 45 hospitals across the country were characterized through toxin profile, pulsed-field gel electrophoresis (PFGE), and sequencing of the tcdC gene. In addition, polymerase chain reaction (PCR) ribotyping and multilocus sequence typing (MLST) were performed on a subset of selected strains. PFGE typing of 719 isolates of C. difficile produced 60 PFGE patterns (subtypes). Subtype 1 was predominant (79% of isolates) and related to the hypervirulent strain (NAP1). Subtype 1 showed 73% relatedness with nine other subtypes, which had a similar tcdC deletion. Subtype 1 corresponded to ribotype 027 and ST1. This report shows the wide dissemination of the hypervirulent strain NAP1/027/ST1 in Chile.

Helicoidal fields and spin polarized currents in carbon nanotube-DNA hybrids.

We report on theoretical studies of electronic transport in the archetypical molecular hybrid formed by DNA wrapped around single-walled carbon nanotubes (CNTs). Using a Green's function formalism in a π-orbital tight-binding representation, we investigate the role that spin-orbit interactions play on the CNT in the case of the helicoidal electric field induced by the polar nature of the adsorbed DNA molecule. We find that spin polarization of the current can take place in the absence of magnetic fields, depending strongly on the direction of the wrapping and length of the helicoidal field. These findings open new routes for using CNTs in spintronic devices.

Inactivation of SARS-CoV-2 isolates from lineages B.1.1.7 (Alpha), P.1 (Gamma) and B.1.110 by heating and UV irradiation.

Currently, the rapid global spread of SARS-CoV-2 is related to G clade (including GH, GR, GRY and GV clades), which are associated with more than 98 % of sequenced viral isolates worldwide. The unprecedented velocity of spread of SARS-CoV-2 outbreak represents a critical need for prevention strategies. Vaccines are recently being available and antiviral drugs have shown limited efficacy in COVID-19 patients. Thus, it is needed to know how to reduce the infectivity of the virus by different physicochemical conditions in order to prevent exposure to contaminated material. This work describes heating and irradiating UV-C light procedures to reduce the infectivity of SARS-CoV-2 belonging to different three lineages. Results of physicochemical treatment showed no differences among viral lineages. Analytical conditions for efficient inactivation of SARS-CoV-2 were determined.

Spatially extended Kondo state in magnetic molecules induced by interfacial charge transfer.

An extensive redistribution of spin density in TBrPP-Co molecules adsorbed on a Cu(111) surface is investigated by monitoring Kondo resonances at different locations on single molecules. Remarkably, the width of the Kondo resonance is found to be much larger on the organic ligands than on the central cobalt atom-reflecting enhanced spin-electron interactions on molecular orbitals. This unusual effect is explained by means of first-principles and numerical renormalization-group calculations highlighting the possibility to engineer spin polarization by exploiting interfacial charge transfer.

A simple method for SARS-CoV-2 detection by rRT-PCR without the use of a commercial RNA extraction kit.

The World Health Organization (WHO) has declared a pandemic caused by a new coronavirus named SARS-CoV-2. The growing demand for commercial kits used for automated extraction of SARS-CoV-2 RNA, a key step before rRT-PCR diagnosis, could cause a shortage of stocks that hinders the rapid processing of samples. Although the recommendation is to use automated methods for nucleic acid extraction, alternatives are necessary to replace commercial kits. However, these alternatives should be as reliable as automated methods. This work describes a simple method to detect SARS-CoV-2 from specimens collected in different preservation media. Samples were previously inactivated by heating and precipitating with a PEG/NaCl solution before rRT-PCR assays for Orf1ab, N and S genes. The new method was compared with an automated protocol of nucleic acid extraction. Both procedures showed similar analytical results. Consequently, this simple and inexpensive method is a suitable procedure for laboratory diagnosis of SARS-CoV-2 infection.

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides.

The growth and exfoliation of two-dimensional (2D) materials have led to the creation of edges and novel interfacial states at the juncture between crystals with different composition or phases. These hybrid heterostructures (HSs) can be built as vertical van der Waals stacks, resulting in a 2D interface, or as stitched adjacent monolayer crystals, resulting in one-dimensional (1D) interfaces. Although most attention has been focused on vertical HSs, increasing theoretical and experimental interest in 1D interfaces is evident. In-plane interfacial states between different 2D materials inherit properties from both crystals, giving rise to robust states with unique 1D non-parabolic dispersion and strong spin-orbit effects. With such unique characteristics, these states provide an exciting platform for realizing 1D physics. Here, we review and discuss advances in 1D heterojunctions, with emphasis on theoretical approaches for describing those between semiconducting transition metal dichalcogenides MX 2 (with M = Mo, W and X = S, Se, Te), and how the interfacial states can be characterized and utilized. We also address how the interfaces depend on edge geometries (such as zigzag and armchair) or strain, as lattice parameters differ across the interface, and how these features affect excitonic/optical response. This review is intended to serve as a resource for promoting theoretical and experimental studies in this rapidly evolving field.

Lymnaeid Snail Vectors of Fascioliasis, Including the First Finding of Lymnaea neotropica in Ecuador, Assessed by Ribosomal DNA Sequencing in the Southern Zone Close to the Peru Border.

PURPOSE: Fascioliasis is a freshwater snail-borne zoonotic trematodiasis of high pathogenicity and wide veterinary repercussions. In South America, moreover, it causes serious public health problems, with high human infection rates in Andean countries. Ecuador offers a worrying risky scenario due to its physiography, including many human infection reports and animal endemicity throughout its Andean highlands. METHODS: Endemic areas with increasing animal fascioliasis were surveyed for lymnaeid snails in the province of Loja, southern Ecuador, close to the border of Peru, the country known to present the widest human fascioliasis endemic zone. The altitude of the sampling sites ranged between 150 and 1770 m a.s.l., and their location was close to human villages. Biotopes surveyed were characterized according to fascioliasis transmission needs. RESULTS: The species Lymnaea schirazensis and L. neotropica were identified by rDNA ITS-2 and ITS-1 sequencing. The non-transmitting L. schirazensis combined haplotype agreed with populations of this species previously reported from northern Ecuador. The finding of the efficient vector L. neotropica is reported for the first time in Ecuador and suggests a passive introduction from neighbouring Peru by uncontrolled livestock transport. CONCLUSIONS: Rice irrigation system implementation, lymnaeid finding on Taraxacum (dandelion) plants which are consumed fresh in salads by people, and Saccharum (sugarcane), whose bark is peeled off with the teeth, represent potential infection sources for humans. The closeness to the Cajamarca human hyperendemic area in northern Peru, where the same two lymnaeids have been also found and triclabendazole resistance reported, is an additional risk to be considered regarding the livestock transborder exchange.

Long range of indirect exchange interaction on the edges of MoS2 flakes.

We study the Ruderman-Kittel-Kasuya-Yosida interaction between two magnetic impurities connected to the edges of zigzag-terminated MoS2 flakes. When the impurities lie on the edges of the flake, the effective exchange interaction exhibits sizable noncollinear Dzyaloshinskii-Moriya character that competes with a strong Ising coupling. We analyze the characteristic decay exponent for doping levels inside the band gap of the infinite layer, corresponding to edge states of the flake at the Fermi level. The characteristic exponents show sub-two-dimensional behavior for these band fillings, with decays much slower than quadratic. The Ising interaction has effectively one-dimensional long range, while the noncollinear component that grows for short impurity separation becomes comparable in magnitude. The resulting tunable exchange interaction on these systems opens the way for the study of interesting phases of impurity arrays with long-range stable helical order.

Detecting coupling of Majorana bound states with an Aharonov-Bohm interferometer.

We study the transport properties of an interferometer composed by a quantum dot (QD) coupled with two normal leads and two one-dimensional topological superconductor nanowires (TNWs) hosting Majorana bound states (MBS) at their ends. The geometry considered is such that one TNW has both ends connected with the QD, forming an Aharonov-Bohm (AB) interferometer threaded by an external magnetic flux, while the other TNW is placed near the interferometer TNW. This geometry can alternatively be seen as a long wire contacted across a local defect, with possible coupling between independent-MBS. We use the Green's function formalism to calculate the conductance across normal current leads on the QD. We find that the conductance exhibits a half-quantum value regardless of the AB phase and location of the dot energy level, whenever the interferometer configuration interacts with the neighboring TNW. These findings suggest that such a geometry could be used for a sensitive detection of MBS interactions across TNWs, exploiting the high sensitivity of conductance to the AB phase in the interferometer.

Tumor fibroso solitario (TFS) parafaríngeo: reporte de caso y revisión de literatura / Parapharyngeal solitary fibrous tumor (SFT): case report and literature review

El espacio parafaríngeo es una región donde puede surgir un amplio espectro de tumores, que son poco frecuentes y comprenden solo el 0,5 al 1,5% de las neoplasias de cabeza y cuello. Generalmente, son hallazgos y suelen presentarse como masas asintomáticas. Incluye neoplasias primarias, extensión directa de regiones adyacentes y enfermedad metastásica. La literatura describe múltiples patologías e histologías que pueden surgir de esta zona, entre ellas, tenemos los tumores fibrosos solitarios, que son un espectro de neoplasias mesenquimatosas fibroblásticas de histogénesis incierta, que generalmente involucran la pleura. Son lesiones muy poco frecuentes y su localización parafaríngea es excepcional, siendo su primer reporte en la literatura en 1993. Se presenta el caso de un tumor fibroso solitario del espacio parafaríngeo evaluado en nuestro centro, con su enfrentamiento diagnóstico, resolución quirúrgica y seguimiento respectivo, con el objetivo de presentar esta patología poco frecuente a nuestros colegas y contribuir al conocimiento médico.

The parapharyngeal space is a region where a wide spectrum of tumors can arise, which are rare and comprise only 0.5% to 1.5% of head and neck neoplasms. They are generally findings and usually present as asymptomatic masses. Includes primary neoplasms, direct extension from adjacent regions, and metastatic disease. The literature describes multiple pathologies and histologies that can arise from this area, among them, we have solitary fibrous tumors, which are a spectrum of fibroblastic mesenchymal neoplasms of uncertain histogenesis, which are generally the pleura. It is a very rare lesion and its parapharyngeal location is exceptional, being its first report in the literature in 1993. We present the case of a solitary fibrous tumor of the parapharyngeal space evaluated in our center, with its diagnos- tic confrontation, surgical resolution and respective follow-up, with the aim of presenting this rare pathology to our colleagues and contributing to medical knowledge.

Flea market finds and global exports: Four multistate outbreaks of human Salmonella infections linked to small turtles, United States-2015.

Zoonotic transmission of Salmonella infections causes an estimated 11% of salmonellosis annually in the United States. This report describes the epidemiologic, traceback and laboratory investigations conducted in the United States as part of four multistate outbreaks of Salmonella infections linked to small turtles. Salmonella isolates indistinguishable from the outbreak strains were isolated from a total of 143 ill people in the United States, pet turtles, and pond water samples collected from turtle farm A, as well as ill people from Chile and Luxembourg. Almost half (45%) of infections occurred in children aged <5 years, underscoring the importance of the Centers for Disease Control and Prevention recommendation to keep pet turtles and other reptiles out of homes and childcare settings with young children. Although only 43% of the ill people who reported turtle exposure provided purchase information, most small turtles were purchased from flea markets or street vendors, which made it difficult to locate the vendor, trace the turtles to a farm of origin, provide education and enforce the United States federal ban on the sale and distribution of small turtles. These outbreaks highlight the importance of improving public awareness and education about the risk of Salmonella from small turtles not only in the United States but also worldwide.

Presencia y biometría de bazo accesorio en individuos chilenos: estudio por tomografía computarizada / Presence and biometry of accessory spleen in Chilean individuals: study by computerized tomography

El bazo se localiza en el cuadrante superior izquierdo del abdomen, relacionándose posteriormente con la 9a a 11a costilla, de las que se separa por el diafragma y el receso costodiafragmático, se localiza por detrás del estómago y lateralmente al riñón izquierdo. Por alteraciones en su desarrollo pueden generarse bazos accesorios (BA), considerándose un tejido ectópico del bazo. Se consideran tejido normal, con los mismos procesos fisiológicos que el bazo principal. Con el propósito de localizar y determinar aspectos biométricos de los mismos, se realizó un estudio de corte transversal y de carácter descriptivo, sobre una muestra de 220 exámenes de TC pertenecientes a pacientes mayores de 18 años del Hospital Regional Hernán Henríquez Aravena, Temuco, Chile. Para este estudio se excluyeron toda aquellas TC con antecedentes de esplenectomía y lesiones de Bazo o peri-esplénicas. El análisis de los datos mostró una prevalencia de 32,3 % de BA, pudiendo ser de una única presencia, dos e incluso tres BA por paciente.De un total de 71 personas que tienen al menos un BA, 34 (47,89 %) fueron de sexo femenino y 37 (52,11 %) de sexo masculino. Hubo 56 pacientes (78,9 %) con un BA, 29 (40,85 %) del sexo femenino y 27 (38,03 %) del masculino; 15 (21,1 %) presentaron más de un BA, 5 (7,04 %) de sexo femenino y 10 (14,08 %) de sexo masculino, si bien se puede observar variación en la cantidad de BA según sexo, no existe una relación estadísticamente significativa entre dichas variables. La ubicación más frecuente encontrada en el plano axial fue la zona antero-medial con 59 casos (66,29 %); asimismo, en el plano sagital, la localización más frecuente fue en el polo inferior con 40 casos (44,44 %). Datos biométricos de estos BA son mostrados en Tablas. Esta información será de gran valor morfológico y médico debido a la escasa literatura existente sobre esta materia en individuos chilenos.

The spleen is located in the upper left quadrant of the abdomen, subsequently related to the 9th to 11th rib, from which it is separated by the diaphragm and the cost-diaphragmatic recess, it is located behind the stomach and laterally to the left kidney. Due to alterations in its development, accessory spleens (AS) can be generated, being considered an ectopic tissue of the spleen. The AS are considered normal tissue, with the same physiological processes as the main spleen. With the purpose of locating and determining biometric aspects of them, a cross-sectional and descriptive study was carried out on a sample of 220 CT scans belonging to patients over 18 years of age at the Hernán Henríquez Aravena Regional Hospital, Temuco, Chile. For this study, all CT scans with a history of splenectomy and spleen or peri-splenic lesions were excluded. The analysis of the data showed a prevalence of 32.3 % of AS, being able to be of a single presence, two and even three AS per patient. Of a total of 71 people who have at least one AS, 34 (47.89 %) were female and 37 (52.11 %) male. There were 56 patients (78.9 %) with a one AS, 29 (40.85 %) of the female sex and 27 (38.03 %) of the male; 15 (21.1 %) presented more than one AS, 5 (7.04 %) female and 10 (14.08 %) male, although variation in the amount of AS according to sex can be observed, no there is a statistically significant relationship between these variables. The most frequent location found in the axial plane was the anteromedial zone with 59 cases (66.29 %); also, in the sagittal plane, the most frequent location was in the lower pole with 40 cases (44.44 %). Biometric data of these AS are shown in tables. This information will be of great morphological and medical value due to the limited existing literature on this subject in Chilean individuals.

Potential landscapes and induced charges near metallic islands in three dimensions.

We calculate electrostatic potential landscapes for an external probe charge in the presence of a set of metallic islands. Our numerical calculation in three dimensions (3D) uses an efficient grid relaxation technique. The well-known relaxation algorithm for solving the Poisson equation in two dimensions is generalized to 3D. In addition, all charges on the system, free as well as induced charges, are determined accurately and self-consistently to satisfy the desired boundary conditions. This allows the straightforward calculation of the potential on the outer boundary using the free space electrostatic Green's function, as well as the calculation of the entire capacitance matrix of the system. Physically interesting examples of nanoscale systems are presented and analyzed.

Electronic states in a cylindrical quantum lens: quantum chaos for decreasing system symmetry.

The eigenvalue problem in a cylindrical lens geometry is studied. Using a conformal mapping method, the shape of the boundary and the Hamiltonian for a free particle are reduced to those of a two-dimensional problem with circular symmetry. The wave functions are separated into two independent Hilbert subspaces due to the inherent symmetry of the problem. For small geometry deformations, the solutions are found by a specially designed perturbation approach. Comparisons between exact and perturbative solutions are made for different lens parameters. As the symmetry of the lens is reduced, the characteristics of the spectrum and the corresponding spatial properties of the wave functions are studied. Our results provide a family of billiard geometries in which the electronic level spectrum is well characterized. In analyzing the level spacing distribution of the spectrum, a strong deviation from the Poisson and Wigner limiting distributions is found as the boundary geometry changes. This intermediate distribution is indicative of a mixed phase space, also revealed explicitly in the classical Poincaré maps we present.

Total colectomy and "J" pouch ileo-anal pull through without temporary diverting ileostomy in the management of ulcerative colitis.

Anal sphincter saving operations are currently the procedures of choice for most patients with ulcerative colitis. In this study we review the experience of The Mayagüez Medical Center, Department of Surgery with 18 patients who underwent a total abdominal colectomy, rectal mucosectomy and "J" pouch ileoanal pull through without a temporary diverting ileostomy in the management of ulcerative colitis. The complications that are associated with this procedure in our patients are: wound infection, postoperative leak, early stricture and intestinal obstruction. Only one patient died and it was due to a massive pulmonary embolism. Finally, we conclude that this procedure should be reserved for well nourished, psycho-logically stable young patients who are willing to tolerate the complications associated with it.

Cecal volvulus after laparoscopic liver biopsy.

Laparoscopic surgery has become widely accepted due to its benefits of less post-operative pain and shorter hospital stay. As with any other new technique, there are associated inherent complications. We present a case of cecal volvulus after laparoscopic liver biopsy. This is the first case reported in the literature of cecal volvulus secondary to laparoscopy.

Squamous cell carcinoma of the prostate: case report and review of literature.

Carcinoma of the prostate, that is adenocarcinoma, is one of the most common malignancies in the male with an estimated incidence for 1991 of 122,000 new cases. On the other hand, squamous cell carcinoma of the prostate, with a median incidence of .5%-1% of all prostatic malignancies, has a similar clinical presentation but differs in treatment response and prognosis. We herein present one case of this histological pattern and review the literature pertaining to it.