The Non-Mesonic Weak Decay of Double-Lambda Hypernuclei: A Microscopic Approach

The non--mesonic weak decay of double--$\Lambda$ hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon--induced mechanism, $\Lambda N\to nN$, widely studied in single--$\Lambda$ hypernuclei, additional hyperon--induced mechanisms, $\Lambda \Lambda\to \Lambda n$, $\Lambda \Lambda\to \Sigma^0 n$ and $\Lambda \Lambda\to \Sigma^-p$, are accessible in double--$\Lambda$ hypernuclei and are investigated here. As in previous works on single--$\Lambda$ hypernuclei, we adopt a nuclear matter formalism extended to finite nuclei via the local density approximation and a one--meson exchange weak transition potential (including the ground state pseudoscalar and vector octets mesons) supplemented by correlated and uncorrelated two--pion--exchange contributions. The weak decay rates are evaluated for hypernuclei in the region of the experimentally accessible light hypernuclei $^{10}_{\Lambda\Lambda}$Be and $^{13}_{\Lambda\Lambda}$B. Our predictions are compared with a few previous evaluations. The rate for the $\Lambda \Lambda\to \Lambda n$ decay is dominated by $K$--, $K^*$-- and $\eta$--exchange and turns out to be about 2.5\% of the free $\Lambda$ decay rate, $\Gamma_{\Lambda}^{\rm free}$, while the total rate for the $\Lambda \Lambda\to \Sigma^0 n$ and $\Lambda \Lambda\to \Sigma^- p$ decays, dominated by $\pi$--exchange, amounts to about 0.25\% of $\Gamma_{\Lambda}^{\rm free}$. The experimental measurement of these decays would be essential for the beginning of a systematic study of the non--mesonic decay of strangeness $-2$ hypernuclei. This field of research could also shed light on the possible existence and nature of the $H$--dibaryon.Comment: 17 pages, 2 figure

Anti-Advanced glycation end-product and free radical scavenging activity of plants from the yucatecan flora

Background: Formation and accumulation of advanced glycation end-products (AGE) is recognized as a major pathogenic process in diabetic complications, atherosclerosis and cardiovascular diseases. In addition, reactive oxygen species and free radicals have also been reported to participate in AGE formation and in cell damage. Natural products with antioxidant and antiAGE activity have great therapeutic potential in the treatment of diabetes, hypertension and related complications. Objective: to test ethanolic extracts and aqueous-traditional preparations of plants used to treat diabetes, hypertension and obesity in Yucatecan traditional medicine for their anti-AGE and free radical scavenging activities. Materials and Methods: ethanolic extracts of leaves, stems and roots of nine medicinal plants, together with their traditional preparations, were prepared and tested for their anti-AGE and antioxidant activities using the inhibition of advanced glycation end products and DPPH radical scavenging assays, respectively. Results: the root extract of C. fistula (IC50= 0.1 mg/mL) and the leaf extract of P. auritum (IC50= 0.35 mg/mL) presented significant activity against vesperlysine and pentosidine-like AGE. Although none of the aqueous traditional preparations showed significant activity in the anti-AGE assay, both the traditional preparations and the ethanolic extracts of E. tinifolia, M. zapota, O. campechianum and P. auritum showed significant activity in the DPPH reduction assay. <65Conclusions: the results suggest that the metabolites responsible for the detected radical-scavenging activity are different to those involved in inhibiting AGE formation; however, the extracts with antioxidant activity may contain other metabolites which are able to prevent AGE formation through a different mechanism

A review of ureteral injuries after external trauma

<p>Abstract</p> <p>Introduction</p> <p>Ureteral trauma is rare, accounting for less than 1% of all urologic traumas. However, a missed ureteral injury can result in significant morbidity and mortality. The purpose of this article is to review the literature since 1961 with the primary objective to present the largest medical literature review, to date, regarding ureteral trauma. Several anatomic and physiologic considerations are paramount regarding ureteral injuries management.</p> <p>Literature review</p> <p>Eighty-one articles pertaining to traumatic ureteral injuries were reviewed. Data from these studies were compiled and analyzed. The majority of the study population was young males. The proximal ureter was the most frequently injured portion. Associated injuries were present in 90.4% of patients. Admission urinalysis demonstrated hematuria in only 44.4% patients. Intravenous ureterogram (IVU) failed to diagnose ureteral injuries either upon admission or in the operating room in 42.8% of cases. Ureteroureterostomy, with or without indwelling stent, was the surgical procedure of choice for both trauma surgeons and urologists (59%). Complications occurred in 36.2% of cases. The mortality rate was 17%.</p> <p>Conclusion</p> <p>The mechanism for ureteral injuries in adults is more commonly penetrating than blunt. The upper third of the ureter is more often injured than the middle and lower thirds. Associated injuries are frequently present. CT scan and retrograde pyelography accurately identify ureteral injuries when performed together. Ureteroureterostomy, with or without indwelling stent, is the surgical procedure of choice of both trauma surgeons and urologists alike. Delay in diagnosis is correlated with a poor prognosis.</p

Non-human TRIM5 variants enhance recognition of HIV-1-infected cells by CD8+ T cells

Tripartite motif-containing protein 5 (TRIM5) restricts human immunodeficiency virus type-1 (HIV-1) in a species-specific manner by uncoating viral particles while activating early innate responses. Although the contribution of TRIM5 proteins to cellular immunity has not yet been studied, their interactions with the incoming viral capsid and the cellular proteasome led us to hypothesize a role for them. Here, we investigate whether the expression of two non-human TRIM5 orthologs, rhesus TRIM5α (RhT5) and TRIM-cyclophilin A (TCyp), both of which are potent restrictors of HIV-1, could enhance immune recognition of infected cells by CD8+ T cells. We illustrate how TRIM5 restriction improves CD8+ T cell-mediated HIV-1 inhibition. Moreover, when TRIM5 activity was blocked by the non-immunosuppressive analog of cyclosporin A, SmBz-CsA, we found a significant reduction in CD107a/MIP1β expression in HIV-1-specific CD8+ T cells. This finding underscores the direct link between TRIM5 restriction and activation of CD8+ T-cell responses. Interestingly, cells expressing RhT5 induced stronger CD8+ T-cell responses through the specific recognition of the HIV-1 capsid by the immune system. The underlying mechanism of this process may involve TRIM5-specific capsid recruitment to cellular proteasomes and increase peptide availability for loading and presentation of HLA class I antigens. In summary, we identified a novel function for non-human TRIM5 variants in cellular immunity. We hypothesise that TRIM5 can couple innate viral sensing and CD8+ T-cell activation to increase species barriers against retrovirus infection. IMPORTANCE: New therapeutics to tackle HIV-1 infection should aim to combine rapid innate viral sensing and cellular immune recognition. Such strategies could prevent seeding of the viral reservoir and the immune damage that occurs during acute infection. The non-human TRIM5 variants, rhesus TRIM5α (RhT5) and TRIM-cyclophilin A (TCyp), are attractive candidates owing to their potency in sensing HIV-1 and blocking its activity. Here, we show that expression of RhT5 and TCyp in HIV-1-infected cells improves CD8+ T cell-mediated inhibition through the direct activation of HIV-1-specific CD8+ T-cell responses. We found that the potency in CD8+ activation was stronger for RhT5 variants and capsid-specific CD8+ T-cells in a mechanism that relies on TRIM5-dependent particle recruitment to cellular proteasomes. This novel mechanism couples innate viral sensing with cellular immunity in a single protein and could be exploited to develop innovative therapeutics for control of HIV-1 infection

Toward real applicability of electro-ozonizers: Paying attention to the gas phase using actual commercial PEM electrolyzers technology

This work focuses on increasing the TRL of electro-ozonizer technology by evaluating the effect of electrolyte composition and operation conditions on the production of ozone, using an actual commercial cell, CONDIAPURE®, in conditions similar to what could be expected in a real application. Not only is attention paid to the changes in the concentration of ozone in the liquid phase, but also to those observed in the gas phase. The electrolyte and its recirculation flowrate, as well as operation temperatures and pressures are found to have significant influence on production rates. The most efficient way to produce ozone is operating at low temperatures and high pressures. In this work, 0.25 and 0.21 mg O3/min were obtained operating at 10 A in electrolytes consisting of aqueous solutions of perchloric and sulfuric acid, respectively, in tests carried out at 13 °C and 2 bars of gauge pressure. The negative effect of scavengers that appear electrochemically along the production of ozone is very important and seems to be partially compensated when organics are present in the solution due to the competition between the reaction of these scavengers with ozone or organics.Este trabajo se enfoca en incrementar el TRL de la tecnología de electro-ozonizadores mediante la evaluación del efecto de la composición del electrolito y las condiciones de operación en la producción de ozono, utilizando una celda comercial real, CONDIAPURE®, en condiciones similares a las que se podrían esperar en una aplicación real. No solo se presta atención a los cambios en la concentración de ozono en la fase líquida, sino también a los observados en la fase gaseosa. Se ha encontrado que el electrolito y su caudal de recirculación, así como las temperaturas y presiones de operación tienen una influencia significativa en las tasas de producción. La forma más eficiente de producir ozono es operando a bajas temperaturas y altas presiones. En este trabajo, 0.25 y 0.21 mg O 3/min operando a 10 A en electrolitos consistentes en soluciones acuosas de ácido perclórico y sulfúrico, respectivamente, en ensayos realizados a 13 °C y 2 bares de presión manométrica. El efecto negativo de los secuestrantes que aparecen electroquímicamente a lo largo de la producción de ozono es muy importante y parece ser parcialmente compensado cuando los orgánicos están presentes en la solución debido a la competencia entre la reacción de estos secuestrantes con el ozono o los orgánicos

New insights about the electrochemical production of ozone

Ozone is a rather attractive oxidant, it is very efficient in the oxidation of pollutants and in the killing of pathogens and does not generate any hazardous waste during its use. Its generation has been constantly sought in an effective way, focusing on obtaining high concentrations of ozone at the lowest possible cost. Recently, electrochemical production of ozone show advantages over conventional corona discharge generation, since this technology do not need very high voltages, feeding oxygen or pure air or dissolving the ozone into wastewater to be treated. However, it is still at early development stage and there is still a long way to reach the high technology readiness levels needed to complete its value chain. Equipment considerations and operation conditions are the key points that need to be understood in order to increase efficiently. Recent novelties in the state of the art of research are summarized in this work

Electrochemical generation of ozone using a PEM electrolyzer at acidic pHs

This work focuses on the electrochemical production of ozone at acidic pHs, evaluating the influence of the salts in the electrolyte, temperature and pressure on the efficiency of its production. Results demonstrate that electrolysis with electrolytes containing perchlorate salts allow obtaining higher concentrations of ozone than electrolytes containing sulfates. Adding to that, the increase in the operation pressure and the decrease in temperature have a positive effect on the production of ozone. This indicates that not only the oxidation of water, but also the oxidation of oxygen is important to explain the electrochemical production of ozone. A simple model considering all these processes is formulated and validated with the experimental results that allow explaining the fundamentals of ozone production in acidic conditions

Understanding ozone generation in electrochemical cells at mild pHs

In this work, the production of ozone at mild pH conditions using a commercial electrochemical PEM cell CONDIAPURE Ⓡ is evaluated, at once a phenomenological model is proposed to understand the basis of the processes that occur inside the cell. At these pH conditions, the production of ozone can be explained from the oxidation of water, while the decomposition of ozone is found to be extremely important to explain the global experimental behavior observed. Not only is this decomposition a chemical but also an electrochemically assisted process which, in turn, can be related to the production of other oxidants in the cell which interact with ozone behaving as predators. The model formulated explains and satisfactorily reproduces the influence of the operation mode, the current intensity applied and presence and destruction of organics, with regression coefficients (r2) ranging from 0.88 to 0.99, helping to understand how the production of ozone should be promoted during electrochemical processes

Is ozone production able to explain the good performance of CabECO® technology in wastewater treatment?

This work intends to go a step further in the application of electrochemical technology to produce ozone, by evaluating the production of ozone with a commercial cell registered as CabECO®, which has been previously used to disinfect heavily polluted water in a successful manner, with a view to ascertaining whether this success may be related to the production of ozone. The CabECO® cell is a PEM electrolyzer; that is to say, one in which anode and cathode are connected through a PEM membrane. Since ozone production on the electrolyte is important and depends on the composition of the liquid, attention must be paid to the electrochemical production of scavengers. Dosing of oxygen as microbubbles has a very positive effect on the production of ozone, while temperature regulation is as well considerably important, as the increase in temperature generated by ohmic losses can lead to important decreases in the efficiency of ozone electrogeneration. Rates within the range 0.06–0.60 mg O3 min−1 are observed; this means that the maximum current efficiency reached is as high as 6.11% (considering oxygen as raw matter). These results are extremely promising as compared with other references in the literature, at once they also indicate there is room for further improvements and a long way to prevent the effect of scavengers and increase the efficiency of the process

Scale-up in PEM electro-ozonizers for the degradation of organics

This work focuses on the scale-up of electro-ozonizers by evaluating the production of ozone and the degradation of clopyralid synthetic wastes using three commercial PEM electrolyzers. The mechanical concept of the three cells is similar: a single compartment cell equipped with a MEA (consisting of a polymer exchange membrane and two pressed diamond coatings electrodes), powered with monopolar electric connection and where water flows on the surface of the electrodes, although the main electrolyte is the Nafion proton exchange membrane. However, their size and recommended operating conditions are not as similar, and their comparison becomes a good scaleup case study. The CabECO® cell consists of 2 MEAs with a total surface area of 24 cm2, a maximum operating current density of 2. 0A. The Mikrozom® cell consists of only one MEA with a net surface electrodic area of 112 mm2 and a maximum operation current density of 1.0 A. Finally, the CONDIAPURE® cell consists of a single MEA with a total surface area of 146 cm2 and a maximum operation current density of 10.0 A. The performance under mild and extreme operating conditions was compared and the results show that, although the cell concept is similar, the results obtained differ very significantly. The three PEM electrolyzers tested can produce ozone efficiently and mineralize completely clopyralid. The only intermediates measured come from the cathodic hydrodechlorination of clopyralid and oxidative intermediates were only detected at trace concentrations. CabECO® cell demonstrates an outstanding performance with very high current efficiencies in the production of ozone. However, the highest mineralization efficiencies are obtained with the Microzon®, which, although it is the PEM electrolyzer with the smallest active area, is the most efficient because can reach high ozone concentrations and achieve the best clopyralid mineralization. Efficiencies as high as 0.47 mg O3 Wh−1 can be obtained with this cell. Slightly lower values are reached by the CabECO® cell (0.38 mg O3 Wh−1). Enlarging electrode surface area does not seem to be a good strategy from the viewpoint of efficiency and it seems to promote side reactions that compete with ozone production and with the degradation of organics. This means that stacking rather than electrode enlarging should be the strategy more advisable for scaling up the electro-ozonation technology.Este trabajo se centra en la ampliación de los electro-ozonizadores mediante la evaluación de la producción de ozono y la degradación de los desechos sintéticos de clopiralida utilizando tres electrolizadores PEM comerciales. El concepto mecánico de las tres celdas es similar: una celda de un solo compartimiento equipada con un MEA (compuesto por una membrana de intercambio de polímero y dos electrodos de revestimiento de diamante prensado), alimentada con conexión eléctrica monopolar y donde el agua fluye en la superficie de los electrodos, aunque el electrolito principal es la membrana de intercambio de protones Nafion. Sin embargo, su tamaño y las condiciones operativas recomendadas no son tan similares, y su comparación se convierte en un buen caso de estudio de ampliación. La celda CabECO® consta de 2 MEA con una superficie total de 24 cm 2, una densidad de corriente operativa máxima de 2. 0A. La celda Mikrozom® consta de un solo MEA con un área superficial neta de electrodos de 112 mm 2 y una densidad de corriente máxima de operación de 1,0 A. Finalmente, la celda CONDIAPURE® consta de un solo MEA con un área superficial total de 146 cm 2y una densidad de corriente máxima de operación de 10.0 A. Se comparó el desempeño en condiciones de operación suaves y extremas y los resultados muestran que, aunque el concepto de celda es similar, los resultados obtenidos difieren muy significativamente. Los tres electrolizadores PEM probados pueden producir ozono de manera eficiente y mineralizar completamente la clopiralida. Los únicos intermedios medidos provienen de la hidrodecloración catódica de clopiralida y los intermedios oxidativos solo se detectaron en concentraciones mínimas. La celda CabECO® demuestra un desempeño sobresaliente con eficiencias de corriente muy altas en la producción de ozono. Sin embargo, las mayores eficiencias de mineralización se obtienen con el Microzon® que, si bien es el electrolizador PEM con menor área activa, es el más eficiente porque puede alcanzar altas concentraciones de ozono y lograr la mejor mineralización de clopiralida. Eficiencias de hasta 0,47 mg OCon esta celda se pueden obtener 3 Wh −1 . La celda CabECO® alcanza valores ligeramente inferiores (0,38 mg O 3 Wh −1 ). Ampliar el área de la superficie del electrodo no parece ser una buena estrategia desde el punto de vista de la eficiencia y parece promover reacciones secundarias que compiten con la producción de ozono y con la degradación de compuestos orgánicos. Esto significa que el apilamiento en lugar de la ampliación de electrodos debería ser la estrategia más recomendable para escalar la tecnología de electro-ozonización