Synthesis, characterization, and water oxidation by a molecular chromophore-catalyst assembly prepared by atomic layer deposition. The "mummy" strategy.

A new strategy for preparing spatially-controlled, multi-component films consisting of molecular light absorbing chromophores and water oxidation catalysts on high surface area, mesoporous metal oxide surfaces is described. Atomic layer deposition (ALD) is used to embed a surface-bound chromophore in a thin layer of inert Al2O3, followed by catalyst binding to the new oxide surface. In a final step, catalyst surface-binding is stabilized by a subsequent ALD overlayer of Al2O3. The ALD assembly procedure bypasses synthetic difficulties arising from the preparation of phosphonic acid derivatized, covalently-linked assemblies. An ALD mummy-based assembly has been used to demonstrate photoelectrochemical dehydrogenation of hydroquinone. Electrocatalytic water oxidation at pH 8.8 is observed over a 2 hour electrolysis period and light-assisted water oxidation over a 6 hour photolysis period with O2 detected with a generator-collector electrode configuration.

Synthesis, structure, and electronic properties of monomeric and dimeric trispyrazolylborate platinum(II) hydride complexes.

Tp'PtMe(H)2 (2) [Tp' = hydridotris(3,5-dimethylpyrazolyl)borate] has been prepared from Tp'PtMe(CO) (1) via reaction with water in a basic acetone/water mixture. Protonation of 2 at one of the pyrazole nitrogen atoms induces methane elimination, and the resulting platinum(II) monohydride solvent intermediate (3) can be trapped by added ligand. Two chiral cationic platinum(II) monohydride complexes of the type [kappa(2)-((Hpz)BHpz2)Pt(H)(L)][BAr'4] [L = MeCN (4), CH2=CH2 (5); pz = 3,5-dimethylpyrazolyl, BAr'4 = tetrakis(3,5-trifluoromethylphenyl)borate] have been isolated. If 2 is protonated in the absence of trapping ligand, a deep red hydride-bridged dinuclear complex, [kappa(2)-((Hpz)BHpz2)Pt(mu-H)]2[BAr'4]2 (6), forms. DFT calculations supplement intuitive expectations regarding 3-center-2-electron bridging orbital descriptions for the electronic structure of this complex. X-ray structure determinations for the monomeric acetonitrile adduct 4 and the dicationic dimer 6 are reported.

Reactions of an amphoteric terminal tungsten methylidyne complex.

Treatment of [Tp'(CO)(2)W triple bond C--PPh(3)][PF(6)] (Tp' = hydridotris(3,5-dimethylpyrazolylborate)) with Na[HBEt(3)] in THF forms the methylidyne complex Tp'(CO)(2)W triple bond C--H via formyl and carbene intermediates Tp'(CO)(C(O)H)W triple bond C- PPh(3) and Tp'(CO)(2)W=C(PPh(3))(H), respectively. Spectroscopic features reported for Tp'(CO)(2)W triple bond C--H include the W triple bond C stretch (observed by both IR and Raman spectroscopy) and the (183)W NMR signal (detected by a (1)H, (183)W 2D HMQC experiment). Protonation of the Tp'(CO)(2)W triple bond C--H methylidyne complex with HBF(4).Et(2)O yields the cationic alpha-agostic methylidene complex [Tp'(CO)(2)W=CH(2)][BF(4)]. The methylidyne complex Tp'(CO)(2)W triple bond C-H can be deprotonated with alkyllithium reagents to provide the anionic terminal carbide Tp'(CO)(2)W triple bond C--Li; a downfield resonance at 556 ppm in the (13)C NMR spectrum has been assigned to the carbide carbon. The terminal carbide Tp'(CO)(2)W triple bond C-Li adds electrophiles at the carbide carbon to generate Tp'(CO)(2)W triple bond C--R (R = CH(3), SiMe(3), I, C(OH)Ph(2), CH(OH)Ph, and C(O)Ph) Fischer carbynes. A pK(a) of 28.7 was determined for Tp'(CO)(2)W triple bond C--H in THF by titrating the terminal carbide Tp'(CO)(2)W triple bond C--Li with 2-benzylpyridine and monitoring its conversion to Tp'(CO)(2)W triple bond C--H with in situ IR spectroscopy. Addition of excess Na[HBEt(3)] to neutral Tp'(CO)(2)W triple bond C--H generates the anionic methylidene complex [Na][Tp'(CO)(2)W=CH(2)]. The synthetic methodology for generating an anionic methylidene complex by hydride addition to neutral Tp'(CO)(2)W triple bond C--H contrasts with routes that utilize alpha-hydrogen abstraction or hydride removal from neutral methyl precursors to generate methylidene complexes. Addition of PhSSPh to the anionic methylidene complex in solution generates the saturated tungsten product Tp'(CO)(2)W(eta(2)-CH(2)SPh) by net addition of the SPh(+) moiety.

Deprotonation of cationic tungsten(IV) aqua-oxo-alkyne complexes to form dioxo-vinyl tungsten(VI) complexes.

Chiral tungsten(IV) aqua-oxo-alkyne complexes, [Tp'W(O)(H2O)(RC identical to CR)][OTf] (R = H (1); R = Me (2)); (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate; OTf = trifluoromethanesulfonate), have been prepared by halide abstraction from iodide precursors. These cationic complexes have been characterized with triflate as the counteranion. The tautomeric dihydroxo isomer has not been observed. The neutral triflate adduct Tp'W(O)(OTf)(HC identical to CH) (3) has also been isolated. Cationic complexes 1 and 2 undergo deprotonation and isomerization when exposed to Al2O3 to give the dioxo-vinyl compounds Tp'W(O)2(CH=CH2) (6) and Tp'W(O)2[C(Me)=C(H)(Me)] (7), reflecting the conversion of the WIV(OH)(RC identical to CR) fragment to WVI(=O)(RC=CHR). The presumed intermediates, neutral oxo-hydroxo compounds Tp'W(O)(OH)(RC identical to CR) (R = H (9); R = Me (10)), can be accessed by deprotonation of 1 or 2 with NaOH. Conversion of 9 to 6 was achieved thermally upon heating at 100 degrees C for 2 days. X-ray structural data have provided solid-state structures of both the cationic aqua complex 2 and the dioxo-vinyl complex 6.

Social blushing.

This article reviews theory and research regarding the physiology, situational and dispositional antecedents, behavioral concomitants, and interpersonal consequences of social blushing and offers a new theoretical account of blushing. This model posits that people blush when they experience undesired social attention. Puzzling questions involving blushing in solitude, the phenomenology of blushing, types of blushing, and blushing in dark-skinned people are discussed.

The pelvic ileal reservoir. An experimental comparison of the 3-loop and 2-loop systems.

In an experimental study the function of the 3-loop (Parks) pelvic ileal reservoir was compared with that of the 2-loop (Utsunomiya) reservoir. Both types achieved satisfactory degrees of continence and evacuation when tested in the defunctioned state. Following restoration of intestinal continuity, the stools of dogs with 3-loop pouches were usually liquid (69 percent) compared to the more formed stools (72 percent) in the 2-loop group, P less than 0.001. At postmortem the reservoirs of the 3-loop group were found to have undergone much greater dilatation (P less than 0.05). These findings suggest that construction of the 3-loop (Parks) pelvic reservoir may lead to retention with overflow if catheterization is not used. It is not clear whether the superior function of the 2-loop pouch is attributable to better motor function or the absence of an efferent limb which allows it to be placed deep in the pelvis.

Capillary gas chromatographic determination of terbutryn and its degradation products in sorghum grain and confirmation of the compounds by mass spectrometry.

An analytical method with a limit of detection 0.05 mg kg-1 is described for the determination of the herbicide terbutryn and its three degradation products, GS-26575, GS-11355 and GS-26831 in sorghum grains using fused silica capillary gas chromatography. Electron impact and methane chemical ionization mass spectra are reported to confirm the characterization of the compounds. No residues of these chemicals were found in sorghum harvested 14 weeks following terbutryn treatment at 0-4.5 kg ha-1.

Low colorectal anastomoses. An experimental assessment of two sutured and two stapled techniques.

Extraperitoneal colorectal anastomoses were constructed in dogs by four methods: one layer of sutures (N = 10), two layers of sutures (N = 10), EEA staples (N = 10), and SPTU staples (N = 10). Dehiscence occurred in eight sutured and one stapled anastomosis (P less than 0.05). The four leaks following two layer sutured anastomoses caused three deaths, whereas all four leaks following one-layer sutured anastomoses were only detected radiologically (P less than 0.02). In the stapled group, the single leak followed EEA anastomosis and was fatal. Anastomotic narrowing was greater in sutured than stapled groups (P less than 0.05). Two layers of sutures produced gross narrowing compared with one layer (P less than 0.002). Two rows of staples (EEA) produced more narrowing than one row (SPTU) (P less than 0.01). Mean hydroxyproline concentrations and bursting pressures on the seventh postoperative day were higher in stapled than sutured anastomoses (P less than 0.05). Submucosal alignment, mucosal continuity, tissue viability, and stage of healing were all inferior for two-layer sutured anastomoses, reaching statistical significance for tissue viability (P less than 0.05). Stapled anastomoses were completed significantly faster (32.6 +/- 7.3 minutes) than sutured (54.1 +/- 8.4 minutes) (P less than 0.01). This experimental study has demonstrated that stapling is a fast and reliable method of colorectal anastomosis with a low complication rate. The shortcomings of the standard two-layer sutured anastomosis are discussed.

Gas chromatographic and mass spectrometric determination of ametryn and its N-dealkylated products.

Gas chromatographic and mass spectrometric properties of ametryn and its N-dealkylated products were studied to establish the potential use in a recently reported method describing the residue analyses of these compounds by gas chromatography with N-P detection. Electron impact mass spectra show base peaks at the molecular ion (M+), and methane chemical ionization mass spectra give base peaks at (M + 1) ion for all the compounds studied. Characteristic mass spectral fragmentations of ametryn, GS-11354, GS-11355, and GS-26831 are presented. Combined gas chromatography-mass spectrometry rather than gas chromatography alone provides unambiguous residue characterization. The technique also allows quantitation of ametryn and its N-dealkylated products that cochromatograph with interfering materials present in a complex substrate.

Comparison of infrared coagulation and rubber band ligation for first and second degree haemorrhoids: a randomised prospective clinical trial.

One hundred and thirty seven previously untreated out-patients with first and second degree haemorrhoids were allocated at random to treatment by infrared coagulation (n=66) or rubber band ligation (n=71). Complete follow up was obtained in 122 patients (60 who had undergone infrared coagulation (group 1), and 62 rubber band ligation (group 2)) at periods from three months to one year after completion of treatment. Infrared coagulation produced a satisfactory outcome in 51 patients (85%): 34 were rendered asymptomatic and 17 improved. Rubber band ligation produced a satisfactory outcome in 57 patients (92%): 33 were rendered asymptomatic and 24 improved. Both methods were equally effective in first and second degree haemorrhoids. The incidence of side effects, particularly discomfort, during and after treatment was significantly higher in those treated by rubber band ligation (p less than 0.001). This appeared to be an appreciable deterrent to future patient compliance. The number of patients losing more than 24 hours from work was higher after rubber band ligation than after infrared coagulation. The number of treatments necessary to cure symptoms did not differ significantly between the two methods. Infrared coagulation was significantly faster than rubber band ligation (p less than 0.001). Infrared coagulation is a simple, fast, and effective outpatient method for the treatment of first and second degree haemorrhoids with fewer troublesome side effects and higher patient acceptability than rubber band ligation.