Ligand-free all-inorganic metal halide nanocubes for fast, ultra-sensitive and self-powered ozone sensors.

Ligand-free all-inorganic lead halide nanocubes have been investigated as ozone sensing materials operating at room temperature. It is found that the nanocubes, crystallined in the orthorhombic CsPbBr3 structure, can operate at room temperature, be self-powered and exhibit high sensitivity and remarkable repeatability. More importantly, they demonstrate higher sensitivity (54% in 187 ppb) and faster response and recovery times compared to hybrid lead mixed halide perovskite (CH3NH3PbI3-x Cl x ) layers, which is the only lead halide perovskite material tested for ozone sensing, to date. Following the exposure to an ozone environment, the stoichiometry and the morphology of the nanocubes remain unaltered. The facile and easy fabrication process together with the high responsivity and stability to the ozone environment makes the bare CsPbBr3 nanocubes a promising material for sensing applications. The sensing properties of the nanoparticulate metal halides presented here provide new exciting opportunities towards engineering reliable and cheap sensing elements for room-temperature operated and self-powered sensors.

Early and late complications of stapled haemorrhoidopexy: a 6-year experience from a single surgical clinic.

PURPOSE: Introduction of stapled hemorrhoidopexy (SH) brought a radical change in the treatment of haemorrhoidal disease. The aim of this study is to evaluate the results and the complications (early and late) from the use of this technique. METHODS: During the last 6 years (2005-2011), 123 patients underwent a SH in our ward. Our sample consists of 79 male and 44 female patients with an average age of 48.2 years (range 22-83 years). Of them, 83 had third-degree haemorrhoidal disease, 34 had fourth-degree and 6 had second-degree bleeding haemorrhoids. The follow-up period was 6-72 months. RESULTS: Pain was minimal or even not existent. Additional sutures or use of adrenaline 1:200.000 for haemostasis were required in 6 patients (4.8%). The bleeding has been diminished with the use of this new haemorrhoidectomy stapler PPH03. Urinary retention, which was observed in 3 patients (2.4%), was temporary and the use of catheter was not needed. As a late complication, 'faecal urgency' occurred in 8 patients (6.5%), and disappeared after some months. No recurrent haemorrhoidal disease occurred. No cases of chronic pain were reported. Average hospital stay was 1 day, except for 2 patients who remained for 2 days for bleeding observation. CONCLUSIONS: The correct application of SH reduces the possible complications. The advantages of the stapled procedure are reduced postoperative pain, the minimal hospital stay and early return to work.

Mycobacterium tuberculosis lipoamide dehydrogenase is encoded by Rv0462 and not by the lpdA or lpdB genes.

The gene encoding dihydrolipoamide dehydrogenase from Mycobacterium tuberculosis, Rv0462, was expressed in Escherichia coli and the protein purified to homogeneity. The 49 kDa polypeptide forms a homodimer containing one tightly bound molecule of FAD/monomer. The results of steady-state kinetic analyses using several reduced pyridine nucleotide analogs and a variety of electron acceptors, and the ability of the enzyme to catalyze the transhydrogenation of NADH and thio-NAD(+) in the absence of D,L-lipoamide, demonstrated that the enzyme uses a ping-pong kinetic mechanism. Primary deuterium kinetic isotope effects on V and V/K at pH 7.5 using NADH deuterated at the C(4)-proS position of the nicotinamide ring are small [(D)(V/K)(NADH) = 1.12 +/- 0.15, (D)V(app) = 1.05 +/- 0.07] when D,L-lipoamide is the oxidant but large and equivalent [(D)(V/K)(NADH) = (D)V = 2.95 +/- 0.03] when 5-hydroxy-1,4-naphthoquinone is the oxidant. Solvent deuterium kinetic isotope effects at pH 5.8, using APADH as the reductant, are inverse with (D)(V/K)(APADH) = 0.73 +/- 0.03, (D)(V/K)(Lip(S))2 = 0.77 +/- 0.03, and (D)V(app) = 0.77 +/- 0.01. Solvent deuterium kinetic isotope effects with 4,4-dithiopyridine (DTP), the 4-thiopyridone product of which requires no protonation, are also inverse with (D)(V/K)(APADH) = 0.75 +/- 0.06, (D)(V/K)(DTP) = 0.71 +/- 0.02, and (D)V(app) = 0.56 +/- 0.15. All proton inventories were linear, indicating that a single proton is being transferred in the solvent isotopically sensitive step. Taken together, these results suggest that (1) the reductive half-reaction (hydride transfer from NADH to FAD) is rate limiting when a quinone is the oxidant, and (2) deprotonation of enzymic thiols, most likely Cys(46) and Cys(41), limits the reductive and oxidative half-reactions, respectively, when D,L-lipoamide is the oxidant.

Dihydroorotate dehydrogenase from Clostridium oroticum is a class 1B enzyme and utilizes a concerted mechanism of catalysis.

Dihydroorotate dehydrogenase from Clostridium oroticum was purified to apparent homogeneity and found to be a heterotetramer consisting of two alpha (32 kDa) and two beta (28 kDa) polypeptides. This subunit composition, coupled with known cofactor requirements and the ability to transfer electrons from L-dihydroorotate to NAD(+), defines the C. oroticum enzyme as a family 1B dihydroorotate dehydrogenase. The results of steady-state kinetic analyses and isotope exchange studies suggest that this enzyme utilizes a ping-pong steady-state kinetic mechanism. The pH-k(cat) profile is bell-shaped with a pK(a) of 6.4 +/- 0.1 for the ascending limb and 8. 9 +/- 0.1 for the descending limb; the pH-k(cat)/K(m) profile is similar but somewhat more complex. The pK(a) values of 6.4 and 8.9 are likely to represent the ionizations of cysteine and lysine residues in the active site which act as a general base and an electrostatic catalyst, respectively. At saturating levels of NAD(+), the isotope effects on (D)V and (D)(V/K(DHO)), obtained upon deuteration at both the C(5)-proR and C(5)-proS positions of L-dihydroorotate, increase from a value of unity at pH >9.0 to sizable values at low pH due to a high commitment to catalysis at high pH. At pH = 6.5, the magnitude of the double isotope effects (D)V and (D)(V/K(DHO)), obtained upon additional deuteration at C(6), is consistent with a mechanism in which C(5)-proS proton transfer and C(6)-hydride transfer occur in a single, partially rate-limiting step.