The removal of the trivalent chromium from the leather tannery wastewater: the optimisation of the electro-coagulation process parameters.

The capacity of the electro-coagulation (EC) process for the treatment of the wastewater containing Cr3+, resulting from a leather tannery industry placed in Medellin (Colombia), was evaluated. In order to assess the effect of some parameters, such as: the electrode type (Al and/or Fe), the distance between electrodes, the current density, the stirring velocity, and the initial Cr3+ concentration on its efficiency of removal (%RCr+3), a multifactorial experimental design was used. The %RCr3+ was defined as the response variable for the statistical analysis. In order to optimise the operational values for the chosen parameters, the response surface method (RSM) was applied. Additionally, the Biological Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), and the Total Organic Carbon (TOC) were monitored during the EC process. The electrodes made of aluminium appeared to be the most effective in the chromium removal from the wastewater under study. At pH equal to 4.52 and at 28°C, the optimal conditions of Cr3+ removal using the EC process were found, as follows: the initial Cr3+ concentration=3,596 mg/L, the electrode gap=0.5 cm, the stirring velocity=382.3 rpm, and the current density=57.87 mA/cm2. At those conditions, it was possible to reach 99.76% of Cr3+ removal, and 64% and 61% of mineralisation (TOC) and COD removal, respectively. A kinetic analysis was performed in order to verify the response capacity of the EC process at optimised parameter values.

Pollution by nitrogen oxides: an approach to NO(x) abatement by using sorbing catalytic materials.

This article summarises the abatement of NO(x) pollution by using sorbing catalytic materials with special relevance to the challenge presented in fixed installations sources. A general vision of the origins of the different pollutants, with emphasis on nitrogen oxides formation, is presented as introduction. The impact of NO(x) pollution comprises additionally a quick view of its toxicity and environmental effects. Actual solutions are presented especially the case of the selective catalytic reduction (SCR) process with its advantages and difficulties. The new concepts for NO(x) abatement are also analysed. In such a way, updated information on solid sorbents for NO(x) removal is provided by including metal oxides, spinelles, perovskites, double-layered cuprates, zeolites, carbonaceous materials, heteropolyacids (HPAs), and supported heteropolyacids. The possibility of reducing those sorbed NO(x) is also underlined. Sorption mechanisms are analysed and clarified by emphasising convergence and disagreement points.

[Silica urolithiasis: report of a new case]. / Litiasis urinaria de sílice: aportación de un nuevo caso.

We report a new case of silica urolithiasis in a 71-year-old patient with background of medicament ingesta (antacid) which could justify the formation of these calculi with so uncommon composition. Medicament calculi amounts about 1% from total urinary calculi. Among them, silica ones (silicon dioxide or Si O2) have been relate din their etiology to chronical ingest of antacid drugs, specially those with magnesium trisilicate. Silica formation in urine is facilitated and conditioned by an acid pH of it. Diagnosis and therapeutical approach does not change in relation to other lithiasis with similar dimension or location. After its composition report, and ruling out the possibility for patient's malingering, urine alkalinization was applied, with an excellent follow-up afterwards. The antacid was substituted by other drug. We analyze the most important aspects about this case. We also make reference to the main related bibliography.

[Viral replication, histologic damage and enzymatic activity in chronic hepatopathies caused by B virus]. / Replicación viral, daño histológico y movimiento enzimático en hepatopatías crónicas por virus B.

The future of patients with chronic hepatitis (HC) due to B virus depends above all on the tendency of the interaction between viral activity and immune response. Viral activity (replication) (RV) can be expressed in these patients by two variants: a) "complete" or "early", associated with the presence in serum of HBsAg, HBeAg, and significant DNA polymerase activity, and b) "incomplete" or "late", in which anti-HBe is found in serum and there are scant or no histopathologic changes ("healthy carriers" in some cases). In prolonged infections viral replication declines gradually, although viral capsid protein continues to be synthesized and DNA-HBV is integrated into the genome. Viral replication per se does not condition the histologic damage (DH) expressive of liver cirrhosis with HBV (HCB). Other publications take a different view of this problem. The increase in viral replication often is proportional to a rise in serum GPT (an expression of histologic damage), but viral replication is not always associated with a progressive disease course. The immune defense leads to cytolysis and subsequent elimination of the HB virus. Some patients with high HBsAg levels have little active forms of liver cirrhosis; the DNA-HBV integrated would be capable of producing HBsAg but not HBcAg. It is precisely this that induces the response of cytotoxic T lymphocytes at the level of the hepatocyte surface. The presence in serum of anti-HBe IgM would be related to the expression of HBcAg on the hepatocyte membrane and/or the liberation of HBcAg particles by lysed hepatocytes. The relationship between the degree of histologic damage and serum aminotransferase levels is better established.

[Viral replication, histologic damage and enzymatic activity in chronic hepatopathies caused by B virus. Analysis of 21 patients]. / Replicación viral, daño histológico y movimiento enzimático en hepatopatías crónicas por virus B. Análisis de 21 pacientes.

In 21 patients from the out-patient clinic of the Internal Medicine Department of our hospital with chronic hepatitis (HC) due to B virus (HBV) and anti-HBC (IgG) serology but not HBsAg, a study was made of the possible correlation between viral replication levels (RV) --as expressed by DNA polymerase values (DNAp)-- and, respectively, histologic changes and serum enzyme movements (GPT, GOT). Our study parted from the diverse criteria cited in the literature concerning the role assigned to viral replication per se and/or immune response per se in the genesis of histologic damage (DH). All patients exhibited signs of moderate clinical and enzymatic activity. The levels of viral replication in the group studies were significant (compared to a control group), which supports the thesis that a certain degree of viral replication, although very attenuated, persists in these patients and is the basis of the continued histological damage that eventually leads to liver cirrhosis (CH) and its derivatives, often with little clinical translation. As regards histologic damage, the correlation with DNAp is reciprocal and of moderate significance, supporting the criterion that the multiform expression of histologic damage in liver cirrhosis due to HBV (HCB) (cellular necrosis, intracellular degenerative phenomena, inflammatory cellular infiltrate, fibrosis) is, at the very least, unproportional to the degree of viral replication and can even be reciprocal. Only the severity of the overall hepatic process remains a function of immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Litiasis urinaria de sílice: aportación de un nuevo caso / Silica urolithiasis: report of a new case

Presentamos un nuevo caso de litiasis urinaria de sílice en un paciente varón de 71 años con antecedentes de ingesta medicamentosa (antiácido) que pudiera justificar la formación de estos cálculos de composición poco común. Los cálculos medicamentosos constituyen aproximadamente un 1 por ciento del total de cálculos urinarios. Dentro de estos, los de sílice (dióxido de silicio o Si O2) han sido relacionados en cuanto a su etiología con la ingesta crónica de fármacos antiácidos, especialmente aquellos que contienen trisilicato de magnesio. La formación de sílice en orina estaría facilitada y condicionada a la presencia de valores ácidos en su pH. El diagnóstico de la litiasis y su enfoque terapéutico no varía con respecto a otros cálculos de similares dimensiones y localización. Tras el informe de su composición, y descartando simulación por parte del paciente, fue instaurada alcalinización urinaria, con una evolución posterior excelente. El antiácido fue sustituido por otro medicamento. Analizamos los aspectos más importantes acerca del caso. Hacemos referencia asimismo a la bibliografía más destacada (AU)

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