Shape-tuned, surface-active and support-free silver oxygen reduction electrocatalyst enabled high performance fully non-PGM alkaline fuel cell.

Exploring non-platinum group metal (n-PGM) based efficient oxygen reduction reaction (ORR) electro-catalysts is highly important for realizing advancement in sustainable next generation-alkaline anion exchange membrane fuel cells (AAEMFCs). Herein, we demonstrate a new "hierarchical shape tuning approach" for the synthesis of controlled sized and shaped non-PGM based Ag ORR electro-catalysts with surface active nano-islands. Hierarchical shapes ranging from spherical (S-AgNs), worm-in-sphere, sphere-in-worm and vermiform (worm-like) Ag nanostructures (V-AgNs) were obtained by precisely varying the ratios of capping agent to dual reducing agents in water at ambient conditions. Compared to S-AgNs, V-AgNs revealed a higher mass normalized ORR Tafel activity (0.303 A mgAg -1 at 0.9 V), onset (1.06 V) and half wave (0.78 V) potentials and higher retention of limiting current density (>88%) after 5000 cycles in 0.5 M potassium hydroxide (KOH) solution attributable to their unique worm like morphology with surface active nano-islands and support free-nature enabled better catalyst utilization. In a fully "non-PGM AAEMFC" (n-PAAEMFC), V-AgNs exhibited the highest fuel cell activity of 115.6 mW cm-2 and stable short-term durability (∼240 h) compared to S-AgNs (41.3 mW cm-2) and previously reported fully n-PAAEMFCs indicating their potential use in next-generation alkaline fuel cells.

Biodegradation of polycyclic aromatic hydrocarbons by an acidophilic Stenotrophomonas maltophilia strain AJH1 isolated from a mineral mining site in Saudi Arabia.

The present study aims at analyzing the degradation of polycyclic aromatic hydrocarbons (PAHs) at acidic conditions (pH = 2) by acidophilic Stenotrophomonas maltophilia strain AJH1 (KU664513). The strain AJH1 was obtained from an enrichment culture obtained from soil samples of mining area in the presence of PAH as sole sources of carbon and energy. Strain AJH1was able to degrade low (anthracene, phenanthrene, naphthalene, fluorene) and high (pyrene, benzo(e)pyrene and benzo(k)fluoranthene) molecular weight PAHs in acidophilic mineral salt medium at pH 2, with removal rates of up to 95% (LMW PAH) and 80% (HMW PAH), respectively. In addition, strain AJH1 treated petroleum wastewater with 89 ± 1.1% COD removal under acidic condition (pH 2) in a continuously stirred reactor. Acidophilic S. maltophilia strain AJH1, hence holds the promise as an effective degrader for biological treatment of PAHs contaminated wastewater at acidic pH.

One pot aqueous synthesis of nanoporous Au85Pt15 material with surface bound Pt islands: an efficient methanol tolerant ORR catalyst.

For the first time, we are reporting the synthesis of Au100-xPtx nanoporous materials in the size range of 7-10 nm through the galvanic replacement of Ag by Pt from Au100-xAg2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the 'Volmer-Weber' growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au100-xPtx NPs. The electrochemical studies using the Au85Pt15/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au85Pt15/C (loading 1.0 mg cm(-2)) as the cathode material and Pt-Ru/C (loading: 0.5 mg cm(-2)) as the anode material performed better (38 mW cm(-2)) than the HiSPEC Pt/C cathode material (16 mW cm(-2)).

Manganese hexacyanoferrate derived Mn3O4 nanocubes-reduced graphene oxide nanocomposites and their charge storage characteristics in supercapacitors.

Mn3O4-reduced graphene oxide (RGO) nanocomposites were prepared by chemical decomposition of the manganese hexacyanoferrate (MnHCF) complex directly on the graphene surface. XRD studies revealed the formation of crystalline hausmannite Mn3O4 nanocubes in the as-prepared nanocomposites without any heat treatment. The FE-SEM images showed the formation of Mn3O4 nanocubes on the graphene surface in the as-prepared nanocomposites. HR-TEM studies confirmed the homogeneous dispersion of ∼25 nm Mn3O4 nanocubes on graphene nanosheets. The amount of Mn3O4 nanocubes and graphene in the nanocomposites was estimated using TGA analysis from room temperature to 800 °C in air. The FT-IR and Raman spectroscopic analysis confirmed the functional groups in the nanocomposites and defects in graphene nanosheets in the nanocomposites. Cyclic voltammetry and galvanostatic charge-discharge experiments demonstrated a high specific capacitance of 131 F g(-1) in 1 M Na2SO4 electrolyte at a current density of 0.5 A g(-1) for the RGM-0.5 nanocomposite. A capacitance retention of 99% was observed for 500 charge-discharge cycles at a current density of 5 A g(-1), which conformed the excellent stability of the RGM electrodes. The prepared Mn3O4-RGO nanocomposites are promising for electrochemical energy storage.

Synergistic effects of pretreatment and blending on fungi mediated biodegradation of polypropylenes.

Environmental issues raise concern on restrict the use of nondegradable polymers and encourage the development of degradable once. This study is carried out was to understand the rate of biodegradation of untreated and pretreated (100°C or UV for 10 days) polypropylene (PP), pro-oxidant blended (MI-PP) and starch blended polypropylenes (ST-PP) with two different fungal strains, Phanerochaete chrysosporium NCIM 1170 (F1) and Engyodontium album MTP091 (F2). About 18.8% and 9.42% gravimetric weight loss and 79% and 57% TGA weight loss (at 400°C) were observed with UV pretreated MI-PP in 1 year with F2 and F1 strains respectively. The amount of lacasse produced by the organism and biomass attached on the polymer surface are correlated with TGA weight loss (0.6-0.93). The formation of extractable oxygenated compounds and unoxidized low-molecular weight hydrocarbons are high in pretreated and blended samples. These results indicate blending and pretreatment strategy leads to an optimal waste-disposal strategy.

Cyclic voltammetric measurements of growth of Aspergillus terreus.

A detailed study using the cyclic voltammogram was done on the live cells of Aspergillus terreus. The peak current values were obtained for different days of growth and plotted against time. The response of cyclic voltammogram showed the phases of the growth of the fungus. The growth curve obtained matched well with the conventional methodology, which assesses the increase of dry weight of the organisms against time. The electrochemical method is more advantageous because it is easy to assess and consumes less time. Further the electrochemical method clearly shows the decline phase which is generally not very defined in the conventional method of assessment of the growth curve. It was confirmed by further experiments that the metabolites were responsible for the anodic peak and not the biomass. Further work is in progress in order to analyze the metabolite(s) that is/are responsible for the anodic peak.

A case of primary drug resistant tuberculosis.

A young man presented with primary multi-drug resistant tuberculosis. The institution of second-line regimes with insufficient efficacy due to clinical inexperience, unreliable sensitivity reports and the inavailability of second-line drugs led to the development of an organism that was resistant to ten anti-tuberculous drugs. Accurate sensitivity testing done in an overseas laboratory enabled the institution of a six-drug regimen that has resulted in clinical cure.

Assessment of growth of Fusarium solani by cyclic voltammetry and possible bioanalytical applications.

Fusarium solani, the fungus isolated from polyurethane waste scraps, was studied for its voltammetric response. The peak current values were obtained for different days and were plotted against time. This electrochemical method based on the voltammetric response showed all the four phases of the growth of the fungus. The growth curve obtained matched well with the conventional methodology, which is obtained by assessing the increase of dry weight of the organisms against time. The electrochemical method is more advantageous than the conventional method because the conventional method is very time consuming and difficult to work with. Further, the electrochemical method clearly shows the decline phase, which is generally not very well defined in the conventional method of assessment of the growth curve. It was confirmed by further experiments that the metabolites were responsible for the anodic peak and not the fungal biomass. Identification of the metabolites that are responsible for the anodic peak is presently being studied.

Tuberculin reactivity and subsequent development of tuberculosis in a cohort of student nurses.

This retrospective study documents a strong correlation between tuberculin reactivity and the subsequent development of active tuberculosis in student nurses. 12% of the 25 student nurses with tuberculin reactions above 20 mm developed tuberculosis over a period of 2 years, compared to only 0.3% of the 341 student nurses with reactions of 20 mm or less. The implications of these findings for preventive therapy are discussed.

Exposure to sputum positive cases of tuberculosis in a government hospital.

A retrospective study was carried out to ascertain the degree of exposure to the tubercle bacillus within Ipoh Hospital. This study reveals that, over a one year period, 92 sputum positive cases were admitted to the general wards. In 11 of these cases, drug resistance was considered to be possible. The mean time from admission to the commencement of treatment was seven days for the newly diagnosed cases. This study thus documents a significant degree of in-hospital exposure to the tubercle bacillus.

Thiamine responsive ankle oedema in detention centre inmates.

Twenty-seven inmates from a detention centre in Perak were evaluated for possible causes of their ankle oedema. Physical examination and biochemical evaluation did not show any evidence of renal or hepatic dysfunction. The cardiac origin of their problem was suggested by the presence of other signs of heart failure in three of them and by radiological evidence of cardiomegaly in 40% of them. All the patients who returned for review demonstrated a prompt clinical response to thiamine replacement therapy.

Huntington disease: report of first case documented in Malaysia.

Huntington disease has not previously been recorded in Malaysia. We report the first case in a local patient with a positive family history. The implications of diagnosing this disease will be discussed.

Beri-beri in immigrant workers--a report of three cases.

Three East Timorese immigrants presented with signs and symptoms of heart failure in early December 1992. One of them also had features of peripheral neuropathy. Another collapsed within 24 hours of admission and attempts at resuscitation failed. The other two showed dramatic response to oral thiamine therapy. An investigation into their dietary history established gross deficiency in fresh vegetables.