Adsorption and photocatalytic decolorization of a synthetic dye erythrosine on anatase TiO2 and ZnO surfaces

The UV radiation assisted photocatalytic decolorization/degradation kinetics of an anionic dye erythrosine (ER), has been studied over TiO2 and ZnO surfaces. Since adsorption is the prerequisite condition for decolorization/degradation of dye molecules in presence of heterogeneous catalysis, the Langmuir and Freundlich isotherms were examined to verify the adsorption intensity. Standard adsorption free energy measurement implies that the adsorption of ER on both TiO2 and ZnO surfaces is spontaneous endothermic process. The effect of catalyst loading (TiO2/ZnO) revealed the fact that the maximum decolorization rate is obtained under an optimized catalyst loading condition. The decolorization efficiency was also investigated over the pH range of 5.0-10.0 indicating that increasing pH enhances decolorization efficiency. The influence of H2O2 on decolorization efficiency was found noticeable since it is a hydroxyl radical provider. The kinetic study of this degradation indicates that under the experimental condition, the decolorization mechanism follows zero order kinetics on the basis of Langmuir-Hinshelwood (L-H) heterogeneous reaction mechanism.

Fabrication of an ultra-sensitive para-nitrophenol sensor based on facile Zn-doped Er2O3 nanocomposites via an electrochemical approach

In this study, a semiconductor-doped nanocomposite material (Zn-doped Er2O3 nano-composites) was prepared via a single-step wet-chemical technique at alkaline pH. Fourier-transform infrared spectroscopy (FT-IR), UV/Vis spectroscopy, photoluminescence spectroscopy (PL), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (XEDS), and X-ray powder diffractometry (XRD) were applied to determine the structural and morphological properties of the Zn-doped Er2O3 nanocomposite. A thin layer of aggregated Zn-doped Er2O3 nanocomposite was fabricated on the flat surface of a glassy carbon electrode (GCE) with 5% ethanolic Nafion as conducting coating binder for the development of a selective and sensitive p-nitrophenol (para-NP) capturing electrochemical probe for environmental remediation. After the fabrication of the sensor, a novel current-potential (I-V) electrochemical approach was applied to determine its selectivity and sensitivity together with all the necessary analytical parameters against para-NP. Moreover, the calibration plot was found to be linear with the linear dynamic range (LDR) of para-NP concentration. The limit of detection (LOD) at a signal-to-noise ratio of 3 (S/N ∼ 3) and sensitivity were also calculated to be 0.033 ± 0.002 pM and 28.481 × 10-2 μA μM-1 cm-2, respectively, based on the gradient of the calibration plot, and the limit of quantification (LOQ) was determined to be 0.11 ± 0.02 pM. This work demonstrates a well-known approach for the first time that can be used for the development of efficient electrochemical sensors. These sensors based on semiconductor doped nanomaterials embedded onto the GCE for the detection of toxic chemicals in an aqueous system as an environmental remediation. It can be further applied for the analysis of real environmental samples and in the healthcare field.

Optimisation of the batch reactor for the removal of cobalt ions from chloride media

A series of experiments were carried out to determine the best medium for the recovery of cobalt by means of an electrogenerative system. Use of the electrogenerative system with a chloride medium had shown promising performance with the highest free energy of -389.8 kJ mol(-1) compared to that with sulphate and nitrate media. Subsequently, the influence of catholyte concentrations on cobalt recovery using the electrogenerative process was carried out by varying the initial cobalt concentration and sodium chloride concentration. The results showed that almost 100% recovery was attained within 1-4 h of the recovery process. Influence of pH was investigated where the electrogenerative system performed best between pH 5.0 and 7.0. Maximum cell performance of 83% with 99% cobalt removal was obtained at 90 min when 100 mg L(-1) of Co(2+) in 0.5 M NaCl was taken as catholyte solution. The values of ΔH(o) and ΔS(o) of the process were evaluated as 33.41 kJ mol(-1) and 0.13 kJ mol(-1), respectively.

Public Health Safety in Relation to Microbiological Quality of Freshly Drawn Cow’s Milk in Bangladesh

The aim of the present study was to determine the microbial quality of freshly drawn cow’s milk belonging to the arsenic affected and non-affected areas. In the present work 25 milk sample were collected from five different arsenic affected and non-affected areas. The analysis comprised enumeration of total viable count (TVC), total coliform count (TCC) and total staphylococcal count (TSC) for the determination of sanitary quality. The highest total viable count, total coliform count and total staphylococcus count were log 5.894 ± 0.221, log 2.832± 0.129 and log 2.898 ± 0.162 respectively. Staphylococcus spp, Escherichia coli, Pseudomonas spp and Bacillus spp were isolated from the milk samples. Among them Escherichia coli were isolated from the maximum milk samples. It is found that the level of microbial quality in terms of TVC, TCC and TSC were high in arsenic affected areas than arsenic non-affected area. It also found that TVC and TCC were positively correlated with each other. This survey indicates that most of the raw milk samples were not satisfactory in course of public health standard as some pathogenic bacteria were detected from these samples and it is necessary to improve the hygienic practices required for the handling and processing of milk.DOI: http://dx.doi.org/10.3329/bjvm.v12i2.21297 Bangl. J. Vet. Med. (2014). 12 (2): 231-236 

Perinatal Complications in Diabetes Mellitus with Pregnancy: Comparison between Gestational Diabetes Mellitus (GDM) and Diabetes Mellitus Prior to Pregnancy

Diabetes is alarmingly high among Bangladeshi people. But there have been very few studies assessing the effect of diabetes on perinatal outcomes, particularly comparing diabetes prior to pregnancy and gestational diabetes (GDM). This cross sectional observational study was conducted in the Department of Obstetrics & Gynaecology, BIRDEM Hospital, Dhaka, Bangladesh from September 2010 to February 2011. Pregnant women admitted in BIRDEM Hospital for delivery after 28 weeks of gestation were selected to assess perinatal complications of GDM and diabetes prior to pregnancy and to compare them after taking permission from institutional review board. Perinatal complications of 50 women with gestational diabetes, 50 pregnant women with diabetes prior to pregnancy, and 50 non diabetic pregnant women as control were studied after taking written consent and the outcomes between GDM, and mother with diabetes prior to pregnancy were compared. Perinatal outcomes including congenital anomalies, birth asphyxia, macrosomia, respiratory distress syndrome (RDS), hypoglycemia, hyperbilirubinaemia, and perinatal mortality were compared. Neonatal complications were significantly higher in both pregnancy with prior diabetes (74%) and gestational diabetes (58%) when compared with non diabetic control (24%). Leading neonatal complications were macrosomia, birth asphyxia, hyperbilirubinaemia, and hypoglycemia. Macrosomia was significantly higher in GDM than non diabetic group (10% vs. 0%, p=0.003). Frequency of birth asphyxia, hyperbilirubinaemia, and hypoglycemia were significantly higher in the infant of mother with prior diabetes (22%, 54%, & 22% respectively) and GDM (20%, 38%, 18% respectively) than that of non diabetic mother (6%, 20%, 0% respectively). Compared to GDM, mother with prior diabetes had more frequent hyperbilirubinaemia (38% vs. 54%, p=0.004) and hypoglycemia (18% vs. 22%, p=0.04). Women with diabetes had worse pregnancy outcomes compared to non-diabetic mothers. Pregnancy prior to diabetes is associated with more frequent complications than gestational diabetes.

Levocarnitine in the management of fatigue in levothyroxine treated hypothyroid patients

Background and objectives: Hypothyroid patients often complain of fatigue even after effective treatment. Thyroid hormone plays an important role in carnitine-dependent long chain fatty acid transport for oxidation and ultimate formation of ATP. Deficiency of L-carnitine has been presumed to disrupt ATP formation leading to fatigue. Present study was designed to assess the role of L-carnitine as a supplement to manage the fatigue state of hypothyroid patients. Methods: Hypothyroid patients receiving levothyroxine (L-T4) and suffering from fatigue symptoms were enrolled. Patients were randomly divided into Group A (Control group, n=35) and Group B (Experimental group, n=36). Patients of Group A were treated with L-T4 only and Group B patients received L-carnitine 2 g/day in addition to L-T4 therapy for 8 weeks. Fatigue was assessed by fatigue severity scale (FSS), physical fatigue (PF) and mental fatigue (MF) scores. Data regarding fatigue status, serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) were collected at the beginning and after 8 weeks of intervention. Result: The mean age of Group A and Group B patients was 33.5±8.1 and 35.4±7.5 years respectively (p>0.05); and the mean body weight was 61.5±9.6 kg and 62.5±8.2 kg respectively (p>0.05). The mean baseline values of different fatigue scores and the serum TSH and FT4 levels of patients of two groups were identical and not significantly different (p>0.05). In Group-A patients, the mean MF score improved significantly (5.2±1.5 vs 4.6±1.4; p=0.01) from baseline score after 8 weeks while the FSS and PF scores did not improve significantly (p>0.05). In Group-B patients, the mean FSS, PF and MF scores improved significantly (p<0.01) from baseline score after 8 weeks of treatment with L-carnitine along with L-LT4 treatment. FSS, PF and MF scores of Group-B patients reduced significantly (p<0.01) compared to Group-A patients after 8 weeks of treatment. FSS, PF and MF scores improved in 88.9%, 77.8% and 47.2% cases respectively in Group-B compared to 20%, 14.3% and 5.7% cases in Group-A. L-carnitine was well tolerated and no severe adverse event was recorded. Conclusion: The results suggest that, administration of L-carnitine along with L-T4 in hypothyroid patients significantly reduced physical and mental fatigue. Ibrahim Med. Coll. J. 2019; 13(2): 45-52

Iron limitation indirectly reduces the Escherichia coli torCAD operon expression by a reduction of molybdenum cofactor availability

The expression of most molybdoenzymes in Escherichia coli has so far been revealed to be regulated by anaerobiosis and requires the presence of iron, based on the necessity of the transcription factor FNR to bind one [4Fe-4S] cluster. One exception is trimethylamine-N-oxide reductase encoded by the torCAD operon, which has been described to be expressed independently from FNR. In contrast to other alternative anaerobic respiratory systems, the expression of the torCAD operon was shown not to be completely repressed by the presence of dioxygen. To date, the basis for the O2-dependent expression of the torCAD operon has been related to the abundance of the transcriptional regulator IscR, which represses the transcription of torS and torT, and is more abundant under aerobic conditions than under anaerobic conditions. In this study, we reinvestigated the regulation of the torCAD operon and its dependence on the presence of iron and identified a novel regulation that depends on the presence of the bis-molybdopterin guanine dinucleotide (bis-MGD) molybdenum cofactor . We confirmed that the torCAD operon is directly regulated by the heme-containing protein TorC and is indirectly regulated by ArcA and by the availability of iron via active FNR and Fur, both regulatory proteins that influence the synthesis of the molybdenum cofactor. Furthermore, we identified a novel regulation mode of torCAD expression that is dependent on cellular levels of bis-MGD and is not used by other bis-MGD-containing enzymes like nitrate reductase.IMPORTANCEIn bacteria, molybdoenzymes are crucial for anaerobic respiration using alternative electron acceptors. FNR is a very important transcription factor that represents the master switch for the expression of target genes in response to anaerobiosis. Only Escherichia coli trimethylamine-N-oxide (TMAO) reductase escapes this regulation by FNR. We identified that the expression of TMAO reductase is regulated by the amount of bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor synthesized by the cell itself, representing a novel regulation pathway for the expression of an operon coding for a molybdoenzyme. Furthermore, TMAO reductase gene expression is indirectly regulated by the presence of iron, which is required for the production of the bis-MGD cofactor in the cell.

Tuberculous pleural effusion

Despite prevention programs, tuberculosis is still endemic in developing countries. Extrapulmonary tuberculosis is increasing globally in the face of recent emergence of Human Immunodeficiency Virus (HIV) infection. Pleural tuberculosis is a common problem in daily clinical practice. We assessed 26 cases of tuberculous pleural effusion admitted in Bangabandhu Sheikh Mujib Medical University from 2002 to 2007. The diagnosis was based upon clinical examination, tuberculin reaction, imaging, pleural fluid analysis and response to antitubercular chemotherapy a surrogate clinical determinant. Apparently promising newer biochemical pleural fluid measurements were not utilized due to a number of limitations. The presenting symptoms found in this prospective analysis are fever (100%), nonproductive cough (73%), pleuritic chest pain (38%), loss of weight (38%) and shortness of breath (38%). A high index of suspicion after confident exclusion of malignancy and pneumonia is a clue to diagnosis. Out of 80 cases of extrapulmonary tuberculosis admitted during the study period, tuberculous pleural effusion constitutes 32.50%.

Shared functions of Fe-S cluster assembly and Moco biosynthesis

Molybdenum cofactor (Moco) biosynthesis is a complex process that involves the coordinated function of several proteins. In the recent years it has become evident that the availability of Fe-S clusters play an important role for the biosynthesis of Moco. First, the MoaA protein binds two [4Fe-4S] clusters per monomer. Second, the expression of the moaABCDE and moeAB operons is regulated by FNR, which senses the availability of oxygen via a functional [4Fe-4S] cluster. Finally, the conversion of cyclic pyranopterin monophosphate to molybdopterin requires the availability of the L-cysteine desulfurase IscS, which is an enzyme involved in the transfer of sulfur to various acceptor proteins with a main role in the assembly of Fe-S clusters. In this review, we dissect the dependence of the production of active molybdoenzymes in detail, starting from the regulation of gene expression and further explaining sulfur delivery and Fe-S cluster insertion into target enzymes. Further, Fe-S cluster assembly is also linked to iron availability. While the abundance of selected molybdoenzymes is largely decreased under iron-limiting conditions, we explain that the expression of the genes is dependent on an active FNR protein. FNR is a very important transcription factor that represents the master-switch for the expression of target genes in response to anaerobiosis. Moco biosynthesis is further directly dependent on the presence of ArcA and also on an active Fur protein.