Phosphorene and phosphorene oxides as a toxic gas sensor materials: a theoretical study.

A systematic study of the adsorption of several harmful gases (CO2, NO, SO2, NH3y H2S) onto black phosphorene and three different black phosphorene oxides (BPO) is carried out through density functional theory calculations. In general, it is shown that BPOs are more suitable adsorbents than pure black phosphorene. Smaller values of adsorption energy correspond to CO2molecules, whilst those exhibiting larger ones are NH3, H2S, NO y SO2. It is found that SO2shows the greater difference in electronic charge transfer as well as the longer time of recovery among all species, being an electron acceptor molecule. Besides, it is revealed that physisorption induces changes of different order in the electronic, magnetic and optical responses of phosphorene systems involved. Greater changes in the electronic structure are produced in the case of NO adsorption. In that case, semiconductor nature and magnetization features of black phosphorene band structure become significantly modified. Moreover, a notorious effect of an externally applied electric field on the molecule adsorption onto BPOs has been detected. In accordance, adsorption energy changes with the applied electric field direction, in such a way that the higher value is favored through an upwards-directed orientation of NO y SO2adsorbates. Results presented could help to enhancing the understanding of BPOs as possible candidates for applications in gas sensing.

Low levels of PAHs and organotin compounds in surface sediment samples from a broad marine area of 25 de Mayo (King George) Island, South Shetland Islands.

The Northern region of the Antarctic Peninsula constitutes the area with the highest human presence in West Antarctica. The human presence, with all the activities associated such as logistic, scientific and tourism operations, represents a potential risk of chemical pollution with both, organic and inorganic contaminants. Under these conditions knowledge about the presence and levels of the main persistent organic pollutants (POPs) is essential to evaluate the environmental status of this ecologically relevant and sensitive area. In this work, which complements our previous study regarding trace elements, we performed the first regional-scale monitoring of 24 PAHs (16 of them included in EPA list of primary pollutant), and organotin compounds (OTCs:TBT, DBT and MBT) in surface sediment from 68 sites comprising six different areas in Maxwell Bay, southeast coast of 25 de Mayo (King George) Island. POPs were quantified in surface sediment samples (20-30 m depth) obtained during two summer Antarctic expeditions by gas chromatography-mass spectrometry (GC-MS). The two most anthropized areas (South Fildes and Potter Cove) showed moderated evidence of pollution for PAHs and OTC. In some sampling sites the concentration of total PAHs was higher than 100 ng/g dw, while TBT was detected in only five samples, two of them located in Potter Cove (ranged between 14 and 18 ng/g dw), and three, located in South Fildes area (ranged between 118 and 416 ng/g dw). Although POPs contamination was evidenced in some samples close to scientific stations, a pollution pattern was not clearly identified.

The utility HBA1c test as a screening biomarker for detecting gestational diabetes mellitus.

BACKGROUND: Glycated Hb (HbA1c) has not been used for the diagnosis of gestational diabetes mellitus (GDM). Measurement of HbA1c levels is less complicated and more comfortable than glucose challenge test (GCT) for pregnant women. We studied HbA1c as a biomarker of GDM and as a screening test to avoid the use of GCT. METHODS: A prospective case-control study involves 745 pregnant women between 24th and 28th gestation week. HbA1c levels were measured and GDM was diagnosed according to Carpenter-Coustan criteria. Mean and SD were calculated for GCT value, HbA1c, age, and body mass index (BMI). A receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic performance of HbA1c test in diagnosing GDM. Cut-off points were calculated to rule out GDM and sensitivity (Se) and specificity (Sp) were also determined. A study of the implementation of HbA1c cut-offs was performed to avoid the GCT or to perform the confirmatory oral glucose tolerance test (OGTT). RESULTS: The area under the curve (AUC) was 0.67 (0.58-0.76). Using 4.6% HbA1c as a cut-off prevented false negatives but only decreased the number of GCTs performed by 7.2%. However, using 4.7% HbA1c resulted in one false negative (reduction of 15.0%). Finally, by selecting 4.8% HbA1c, we found two false negatives, but there were 25.9% who do not require a GCT. CONCLUSIONS: Adoption of HbA1c as a screening test for GDM may eliminate the need of GCT. Although the HbA1c test does not have sufficient Se and Sp to be used as the only diagnostic test, the use of a rule-out strategy in combination with the OGTT could be useful.

Element concentrations of environmental concern in surface sediment samples from a broad marine area of 25 de Mayo (King George) Island, South Shetland Islands.

Western Antarctica (WA) constitutes the area with the highest human presence in the white continent and also the region where the effects of global warming are more evident worldwide. Such human presence represents a potential risk of pollution with both, organic and inorganic contaminants. Global warming also could modify dynamics and transport of the pollutants, increasing summer water runoff, ice melting and iceberg scouring. Under this fast-changing scenario, knowledge about the concentration of contaminants is essential to evaluate the environmental status of this ecologically relevant area. In this work, we performed the first regional-scale monitoring of 9 trace elements (Cr, Co, Ni, Cu, Zn, As, Pb, Cd and Hg), as well as Fe and Mn, in surface sediment from 64 sites comprising six different areas in Maxwell Bay, 25 de Mayo (King George) Island. Target elements were quantified in surface sediment samples (20-30 m depth) obtained during two summer Antarctic expeditions: 2010/11 and 2011/12 by inductively coupled plasma linked to a quadrupole mass spectrometer (ICP-MS). Based on the average values observed for the reference areas, baseline values were defined for the studied region. A regional enrichment in Cu (compared with the global mean upper crust) was observed and related to the widespread mineralization of volcanic rocks. The most anthropized area (South Fildes) mainly showed sediment class 3 (moderately polluted) for Pb, Cd and Hg with a number samples revealing some highly contaminated hot spots. Although elemental contamination in some samples close to scientific stations or sites where logistic operations were evidenced, a pollution pattern was not clearly identified. The present work represents the first regional-scale attempt to define the baseline values and the anthropic impacts in this region of the WA and also provides the first data about Hg concentration in surface sediment of the study area.

Design and simulation of origami structures with smooth folds.

Origami has enabled new approaches to the fabrication and functionality of multiple structures. Current methods for origami design are restricted to the idealization of folds as creases of zeroth-order geometric continuity. Such an idealization is not proper for origami structures of non-negligible fold thickness or maximum curvature at the folds restricted by material limitations. For such structures, folds are not properly represented as creases but rather as bent regions of higher-order geometric continuity. Such fold regions of arbitrary order of continuity are termed as smooth folds. This paper presents a method for solving the following origami design problem: given a goal shape represented as a polygonal mesh (termed as the goal mesh), find the geometry of a single planar sheet, its pattern of smooth folds, and the history of folding motion allowing the sheet to approximate the goal mesh. The parametrization of the planar sheet and the constraints that allow for a valid pattern of smooth folds are presented. The method is tested against various goal meshes having diverse geometries. The results show that every determined sheet approximates its corresponding goal mesh in a known folded configuration having fold angles obtained from the geometry of the goal mesh.

[Evaluation of semen parameters in long term cryopreserved samples for over 10 years]. / Evaluación de los parámetros seminales en muestras criopreservadas por más de 10 años.

BACKGROUND: Sperm samples subjected to cryopreservation are vulnerable, reflecting changes in membrane integrity, mobility and DNA. OBJECTIVE: To assess the rate of DNA fragmentation, sperm mobility and recovery viability in capacitated semen samples after cryopreservation for over 10 years. MATERIAL AND METHOD: Longitudinal, prospective, observational study of 19 seminal samples cryopreserved for more than 10 years, in a mexican fertility center. The sample was divided into 4 groups: Group CX (Surgery), Group IVF (in vitro fertilization), OAT Group (Oligo- astheno-teratozoospermia) and QX Group (Chemotherapy), in order to compare variables such as: recovery in mobility, DNA fragmentation index and sperm viability. Continuous variables were designated as means ± SD, and categorical variables as frequencies and percentages. JMP-V9 program was used. RESULTS: There is no difference in storage time and initial volume. The concentration, total mobility, total motile cells and morphology in OAT group are different from the rest. There is difference in initial morphology of the tail, showing more altered parameters in CX and IVF groups. In the CX, FIV and OAT Groups was achieving a mobility recovery of 27.34%, 30.02% and 55.24% respectively. The QX group presented no change. By analyzing the viability only OAT group presented < 50% intact sperm. For DNA fragmentation CX Groups and IVF showed the lowest rate (3.5.± 2.5 and 3.5 ± 3.01 respectively) compared with OAT Groups and QX (9.8 ± 0.2 and 12, 17 ± 3.9). CONCLUSION: It is possible to store semen samples for a long period of time, retrieving suitable viability sperm useful for assisted reproduction techniques.

Influence of nutrients addition and bioaugmentation on the hydrocarbon biodegradation of a chronically contaminated Antarctic soil.

Complexity involved in the transport of soils and the restrictive legislation for the area makes on-site bioremediation the strategy of choice to reduce hydrocarbons contamination in Antarctica. The effect of biostimulation (with N and P) and bioaugmentation (with two bacterial consortia and a mix of bacterial strains) was analysed by using microcosms set up on metal trays containing 2.5 kg of contaminated soil from Marambio Station. At the end of the assay (45 days), all biostimulated systems showed significant increases in total heterotrophic aerobic and hydrocarbon-degrading bacterial counts. However, no differences were detected between bioaugmented and nonbioaugmented systems, except for J13 system which seemed to exert a negative effect on the natural bacterial flora. Hydrocarbons removal efficiencies agreed with changes in bacterial counts reaching 86 and 81% in M10 (bioaugmented) and CC (biostimulated only) systems. Results confirmed the feasibility of the application of bioremediation strategies to reduce hydrocarbon contamination in Antarctic soils and showed that, when soils are chronically contaminated, biostimulation is the best option. Bioaugmentation with hydrocarbon-degrading bacteria at numbers comparable to the total heterotrophic aerobic counts showed by the natural microflora did not improve the process and showed that they would turn the procedure unnecessarily more complex.

[Changes in viability of two Antarctic marine bacteria exposed to solar radiation in the water column: influence of vertical mixing]. / Cambios en la viabilidad de dos bacterias marinas antárticas expuestas a la radiación solar en la columna de agua: influencia de la mezcla vertical.

The effect of UV radiation on two Antarctic marine bacterial strains (UVps and UVvi) was studied in the water column of Potter Cove (South Shetland, Antarctica). Quartz flasks were filled with the bacterial suspensions and exposed to solar radiation at 0 m, 1 m and 3 m depth. Assays using flasks exposed to direct solar radiation and others using flasks covered with/by interferential filters which discriminate between UVA and UVB, were performed. In other assays, a vertical mixing of 4 m/h was simulated. Both strains showed a significant decrease in viability (expressed as colony - forming units) when exposed to a surface UVB dose of 8.4 kJ m(-2). Studies with interferential filters showed a significant decrease at 0 and 1 m depth under both UV treatments. The UVps strain appeared to be more sensitive to UVB than to UVA. Damage produced by UVB was attenuated by the vertical mixing when the surface UVB dose was 4.8 kJ m(-2). This effect was not observed when surface UVB dose was 7.7 kJ m(-2). These results show that the negative effect caused by UVB radiation on the bacterioplankton would be significant only in the first meter of water column of the Antarctic coastal waters with high levels of suspended particulate material.

Cambios en la viabilidad de dos bacterias marinas antárticas expuestas a la radiación solar en la columna de agua: influencia de la mezcla vertical / Changes in viability of two Antarctic marine bacteria exposed to solar radiation in the water column: influence of vertical mixing

Se estudió el efecto de la radiación ultravioleta (RUV) sobre dos cepas bacterianas marinas antárticas (UVps y UVvi) en la columna de agua de la caleta Potter (Shetland del Sur, Antártida). Frascos de cuarzo con las cepas en estudio fueron expuestos a la radiación solar en superficie, a 1 m y a 3 m de profundidad. Se realizaron ensayos con exposición directa y con filtros interferenciales que discriminaron la radiación UVA y la UVB. En otros ensayos se simuló una mezcla vertical de 4 m/h. Ambas cepas mostraron una disminución significativa del número de unidades formadoras de colonias, tanto en superficie como a 1 m de profundidad, luego de exponerlas a dosis superficiales de UVB de 8,4 kJ m-2. El estudio con filtros interferenciales mostró una disminución significativa de la viabilidad en ambos tratamientos UV en superficie y a 1 m. La cepa UVps mostró mayor sensibilidad a la UVB que a la UVA. La mezcla vertical amortiguó el daño causado por la UVB cuando la dosis en superficie fue de 4,8 kJ m-2. Este efecto amortiguador no se observó cuando la dosis en superficie fue de 7,7 kJ m-2. Estos resultados muestran que el efecto negativo de la RUV sobre el bacterioplancton sería particularmente importante en el primer metro de profundidad de las aguas costeras antárticas con abundante material particulado en suspensión.

The effect of UV radiation on two Antarctic marine bacterial strains (UVps and UVvi) was studied in the water column of Potter Cove (South Shetland, Antarctica). Quartz flasks were filled with the bacterial suspensions and exposed to solar radiation at 0 m, 1 m and 3 m depth. Assays using flasks exposed to direct solar radiation and others using flasks covered with/by interferential filters which discriminate between UVA and UVB, were performed. In other assays, a vertical mixing of 4 m/h was simulated. Both strains showed a significant decrease in viability (expressed as colony - forming units) when exposed to a surface UVB dose of 8.4 kJ m-2. Studies with interferential filters showed a significant decrease at 0 and 1 m depth under both UV treatments. The UVps strain appeared to be more sensitive to UVB than to UVA. Damage produced by UVB was attenuated by the vertical mixing when the surface UVB dose was 4.8 kJ m-2. This effect was not observed when surface UVB dose was 7.7 kJ m-2. These results show that the negative effect caused by UVB radiation on the bacterioplankton would be significant only in the first meter of water column of the Antarctic coastal waters with high levels of suspended particulate material.

Neuropatías por compresión de repetición en paciente afecta de síndrome de MNGIE / Repeated pressure neuropathy in patient with mngie syndrome

Presentamos el caso de un paciente con encefalopatía mioneurogastrointestinal (síndrome de MNGIE) remitido al Servicio de Rehabilitación del Hospital Morales Meseguer. El motivo de la consulta fue la aparición de neuropatías por compresión del nervio peroneo común a consecuencia de ingresos sucesivos, de larga duración, por cuadros de descompensación gastrointestinal

This is a clinical case of myoneurogastrointestinal encephalopathy (MNGIE syndrome) referred to the Hospital Morales Meseguer Rehabilitation Service because of Pressure Neuropathies of fibularis communis nerve secondary to long hospital stay after gastrointestinal decompensation episodes

Prevención, diagnóstico y tratamiento de la osteoporosis inducida por corticoides Patrones de conducta en reumatólogos del caribe colombiano / Prevention, diagnosis and treatment of glucocorticoid-induced osteoporosis Patterns of conduct in rheumatologist of Colombian Caribean

Objetivo: Establecer los factores asociados a la decisión clínica de implementar medidas diagnósticas y terapéuticas de OIC, por parte de los reumatólogos, en pacientes tratados con glucocorticoides, en la ciudad de Barranquilla- Colombia, febrero a mayo de 2004. Pacientes y métodos: Se escogieron 121 pacientes consecutivos en tratamiento con corticoides (P.O o IM) por más de 6 semanas que acudían a consulta de reumatología durante los meses de febrero a mayo de 2004. Los pacientes debían tener al menos dos o más consultas con su médico tratante para ingresar en el estudio. En los pacientes incluidos se implementó un formulario de recolección de datos que incluía variables demográficas y clínicas, así como la presencia o ausencia de factores de riesgo para OIC, además de la conducta empleada para el diagnóstico, prevención y/o tratamiento de los pacientes. Resultados: De 121 pacientes incluidos, 103 (85,1 por ciento) eran de sexo femenino y 18 (14,9 por ciento) eran de sexo masculino. 76 pacientes (62,8 por ciento) eran menores de 50 años, y 45 (37,2 por ciento) eran mayores de 50 años. Se indicaron corticoides en 68 pacientes con artritis reumatoide (56,2 por ciento) y en 31 pacientes con LES (25,6 por ciento). Se informó conducta diagnóstica en 50,41 por ciento de los pacientes, distribuidos así: DEXA periférico (Accudexa) 52,4 por ciento, DEXA central (fémur, cuerpo total, columna y columna y cadera) 16,3 por ciento, Ultrasonido de calcáneo (14,7 por ciento), DEXA antebrazo distal y UD (9,2 por ciento). Se informó conducta terapéutica en 96 pacientes (79,3 por ciento). De la población total, 17 pacientes (14 por ciento) recibieron calcio, 26 (21,5 por ciento) recibieron vitamina D y 53 (43,8 por ciento), calcio más vitamina D; 6 pacientes recibieron Bifosfonatos y 1 recibió Calcitonina. Conclusiones: En nuestra población el 50,41 por ciento de los pacientes recibió algún tipo de conducta diagnóstica y 79,3 por ciento, conducta terapéutica, cifras que se comparan favorablemente con las informadas internacionalmente. Sin embargo, para el diagnóstico y tratamiento se emplearon métodos y prescripciones de menor evidencia científica y menor costo que reflejan la capacidad económica de la mayoría la población atendida

[Helicobacter pylori infection in a group of HIV/AIDS patients]. / Infección por Helicobacter pylori en un grupo de pacientes VIH/SIDA.

The prevalence of H. pylori infection in AIDS patients has been controversial. A. controlled prospective and descriptive study was conducted in a group of 64 HIV-infested patients. H. pylori detection was carried out by endoscopic study during which two biopsy samples of gastric antrum and body were taken for the histologic study and other 2 samples of gastric antrum and body for urease testing. H.pylori infection prevalence was 56.3%. The comparison group was composed by 110 serologically HIV-negative patients, with an infection prevalence rate of 77.2%. In the HIV-AIDS group, the frequency of gastric ulcer was 1,5% and no duodenal ulcer was found whereas the comparison group showed a frequency of gastric and duodenal ulcers of 1.8 and 15.5% respectively. HIV+/AIDS patients in category I exhibited an H. pylori infection prevalence of 68.7%, category II, 39.2% and category III, 21,0%. A reversed association was observed between the level of immune deterioration and the prevalence of H. pylori infection.

Sperm dysfunction in subfertile patients with varicocele and marginal semen analysis.

A comparative analysis of potentially functional spermatozoa per ejaculate, progressive motility, hypo-osmotic swelling test, acrosome integrity and sperm viability (24 and 48 h) was carried out in a group of 40 subfertile patients with varicocele and marginal semen analysis and 40 fertile subjects, in order to identify subclinical abnormalities that may explain subfertility. Patients with varicocele had lower numbers of potentially functional spermatozoa per ejaculate, progressive motility, acrosome and membrane integrity and sperm viability. These abnormalities were not related to the grade of varicocele, testicular volume or serum FSH concentration. A positive correlation between the hypo-osmotic swelling test and progressive motility (r = 0.71) and between potentially functional spermatozoa and the hypo-osmotic swelling test (r = 0.69) was found in patients with varicocele. These data suggest that some of the deleterious effects produced by the varicocele might be related to sperm migration and viability in the female genital tract and others to sperm-zona interaction and/or sperm-egg fusion.

[The patient's perspective. Reflections on past, present, and future in the chronic illness experience]. / La perspectiva de los sujetos enfermos. Reflexiones sobre pasado, presente y futuro de la experiencia del padecimiento crónico.

The illness experience is a relevant issue in current research and academic discussions. A growing number of research initiatives have undertaken to account for the subject's perspective and subjectivity in the health field. This paper discusses our research team's approach and results in studying the experience of people living with chronic illness. Our perspective is based upon the production in this relatively new field as well as health-related discussions in Latin America. The illness experience calls for an understanding of it as a subjective and existential phenomenon, entailing the phenomenological arena, immersed in the process where ill people "produce" and "reproduce" themselves. The unfolding and course of the illness as well as treatment management are some salient dimensions we evoke. Some lines of future work are presented in order to create a research agenda, highlighting its implications for existing proposals pertaining to health reform in our Latin American countries.