High pressure clamp for electrical measurements up to 8 GPa and temperature down to 77 K

A compact clamp-type high pressure cell for carrying out electrical conductivity measurements on small solid samples of size 1 mm or less at pressures upto 8 GPa (i.e., 80 kbar) and for use down to 77 K has been designed and fabricated. The pressure generated in the sample region has been calibrated at room temperature against the polymorphic phase transitions of Bismuth and Ytterbium. The pressure relaxation of the clamp at low temperatures has been estimated by monitoring the electrical conductivity behavior of lead. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

Aspects of tautomerism. 8. Solvolysis of some pseudo and normal acid chlorides

Pseudo acid chlorides derived from levulinic acid ando-benzoyl-benzoic acid, solvolyse in aqueous acetone, aqueous dioxane and aqueous dimethylformamide by aS Nl process. Their reaction pattern is distinct from that of typical normal acid chlorides, viz.,p-benzoylbenzoyl chloride and fluorene-9-one-1-carboxylic acid chloride, which solvolyse by aS N2 pathway. No evidence for tautomerism could be obtained either between the normal and pseudo forms of the acid chlorides or the derived ion pairs.

Proton translocation coupled to electron transfer reactions in terminal oxidases

Terminal oxidases are the final proteins of the respiratory chain in eukaryotes and some bacteria. They catalyze most of the biological oxygen consumption on Earth done by aerobic organisms. During the catalytic reaction terminal oxidases reduce dioxygen to water and use the energy released in this process to maintain the electrochemical proton gradient by functioning as a redox-driven proton pump. This membrane gradient of protons is extremely important for cells as it is used for many cellular processes, such as transportation of substrates and ATP synthesis. Even though the structures of several terminal oxidases are known, they are not sufficient in themselves to explain the molecular mechanism of proton pumping. In this work we have applied a complex approach using a variety of different techniques to address the properties and the mechanism of proton translocation by the terminal oxidases. The combination of direct measurements of pH changes during catalytic turnover, time-resolved potentiometric electrometry and optical spectroscopy, made it possible to obtain valuable information about various aspects of oxidase functioning. We compared oxygen binding properties of terminal oxidases from the distinct heme-copper (CcO) and cytochrome bd families and found that cytochrome bd has a high affinity for oxygen, which is 3 orders of magnitude higher than that of CcO. Interestingly, the difference between CcO and cytochrome bd is not only in higher affinity of the latter to oxygen, but also in the way that each of these enzymes traps oxygen during catalysis. CcO traps oxygen kinetically - the molecule of bound dioxygen is rapidly reduced before it can dissociate. Alternatively, cytochrome bd employs an alternative mechanism of oxygen trapping - part of the redox energy is invested into tight oxygen binding, and the price paid for this is the lack of proton pumping. A single cycle of oxygen reduction to water is characterized by translocation of four protons across the membrane. Our results make it possible to assign the pumping steps to discrete transitions of the catalytic cycle and indicate that during in vivo turnover of the oxidase these four protons are transferred, one at a time, during the P→F, F→OH, Oh→Eh, and Eh→R transitions. At the same time, each individual proton translocation step in the catalytic cycle is not just a single reaction catalyzed by CcO, but rather a complicated sequence of interdependent electron and proton transfers. We assume that each single proton translocation cycle of CcO is assured by internal proton transfer from the conserved Glu-278 to an as yet unidentified pump site above the hemes. Delivery of a proton to the pump site serves as a driving reaction that forces the proton translocation cycle to continue.

Micromolar concentration of pentoxifylline improves development in vitro of hamster 8-cell embryos: conrmation of biological viability by embryo transfer

The inßuence of the sperm motility stimulant pentoxifylline (PF) on preimplantation embryo development in hamsters was evaluated. Eight-cell embryos were cultured in hamster embryo culture medium (HECM)-2, with or without PF (0· 0233·6 mM). There was 90%, 37% and 29% inhibition of blastocyst development by 3·6 (used for human sperm), 0·9 and 0 ·45 mM PF, respectively. However, 23 µM PF (exposed to hamster oocytes during IVF) signicantly (P < 0·05) improved blastocyst development (63· 6% v. 51· 8%); morulae development was, however, not curtailed by 0·45 mM or 0·9 mM PF (51·8%±6·0 or 50·5%±11·3, respectively). Post-implantation viability of PF-treated embryos was assessed by embryo transfer; 43% of 80 PF-treated embryos implanted compared with 40% of 79 control embryos. Of the 9 recipients, 6 females delivered pups (19, i.e. 16% of transferred embryos or 53% of implanted embryos). These data show that in hamsters, continuous presence of PF at 0·45-3·6 mM is detrimental to 8-cell embryo development whereas 23 µM PF improves the development of embryos to viable blastocysts which produce live offspring.

Conformational studies of the triphenylphosphazenyl side chain in cyclophosphazenes. II. Crystal and molecular structure of 2,4,4,6,6,8,8-heptachloro-2-triphenylphosphazenylcyclotetra(phosphazene), N4P4Cl7(NPPh3)

Abstract is not available.

Ethyl 4-(3-hydroxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate

In the molecular structure of the title compound, C21H25NO4, the dihydropyridine ring adopts a flattened boat conformation while the cyclohexenone ring is in an envelope conformation. In the crystal structure, molecules are linked into a two-dimensional network parallel to (10 (1) over bar) by N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds. The network is generated by R-4(4)(30) and R-4(4)(34) graph-set motifs.

2-Chloro-7,8-dimethylquinoline-3-carbaldehyde

All the non-H atoms of the title compound, C12H10ClNO, lie on a crystallographic mirror plane orientated perpendicular to the crystallographic b axis.

2-Chloro-8-methoxyquinoline-3-carbaldehyde

In the title compound, C11H8ClNO2, the quinoline fused-ring system is almost planar (r.m.s. deviation = 0.020 angstrom). The formyl group is slightly bent out of the quinoline plane [deviation of the O atom = 0.371 (2) angstrom].

Oh Holly, The Fish is Dead

From Kurt Vonnegut to Stephen King, many novelists use metanarrative techniques to insert fictional versions of themselves in the stories they tell. The function of deploying such techniques is often to draw attention to the liminal space between the fictional constructs inherent in the novel as a form, and the real world from which the constructs draw inspiration, and indeed, are read by an audience. For emerging writers working in short form narratives, however, the structural demands of the short story or flash fiction make the use of similar techniques problematic in the level of depth to which they can be deployed. ‘Oh Holly, the fish is dead’ is the fourth in a series of short stories that work to overcome the structural limitations of a succinct form by developing a fractured fictional version of the author over a number of pieces and published across a range of sites. The accumulative affect is a richer metanarrative textual arrangement that also allows for the individual short stories to function independently.

2-Chloro-3-hydroxymethyl-7,8-dimethylquinoline

All non-H atoms of the title compound, C12H12ClNO, are co-planar (r.m.s. deviation = 0.055 angstrom). The hydroxy H atom is disordered over two positions of equal occupancy. In the crystal, molecules are linked by O-H center dot center dot center dot O hydrogen bonds, generating zigzag chains running along the b axis.

Magnetic behaviour in metal-organic frameworks-Some recent examples

The article describes the synthesis, structure and magnetic investigations of a series of metal-organic framework compounds formed with Mn+2 and Ni+2 ions. The structures, determined using the single crystal X-ray diffraction, indicated that the structures possess two- and three-dimensional structures with magnetically active dimers, tetramers, chains, two-dimensional layers connected by polycarboxylic acids. These compounds provide good examples for the investigations of magnetic behaviour. Magnetic studies have been carried out using SQUID magnetometer in the range of 2-300 K and the behaviour indicates a predominant anti-ferromagnetic interactions, which appears to differ based on the M-O-C-O-M and/or the M-O-M (M = metal ions) linkages. Thus, compounds with carboxylate (Mn-O-C-O-Mn) connected ones, [C3N2H [Mn(H2O)''C6H3(COO)(3)''], I, [''Mn(H2O (3)''aEuroeC(12)H(8)O(COO)(2)'']center dot H2O, II, [''Mn(H2O)''aEuroeC(12)H(8)O(COO)(2)''], III, show simple anti-ferromagnetic behaviour. The compounds with Mn-O/OH-Mn connected dimer and tetramer units in [NaMn''C6H3(COO)(3)''], IV, [Mn-2(A mu(3)-OH) (H2O)(2)''C6H3(COO)(3)'']center dot 2H(2)O, V, show canted-antiferromagnetic and anti-ferromagnetic behaviour, respectively. The presence of infinite one-dimensional -Ni-OH-Ni- chains in the compound, [Ni-2(H2O)(A mu(3)-OH)(2)(C8H5NO4], VI, gives rise to ferromagnet-like behaviour at low temperatures. The compounds, [Mn-3''C6H3(COO)(3)''(2)], VII and [''Mn(OH)''(2)''C12H8O(COO)(2)''], VIII, have two-dimensional infinite -Mn-O/OH-Mn- layers with triangular magnetic lattices, which resemble the Kagome and brucite-like layer. The magnetic studies indicated canted-antiferromagnetic behaviour in both the cases. Variable temperature EPR and theoretical magnetic modelling studies have been carried out on selected compounds to probe the nature of the magnetic species and their interactions with them.

2-Chloro-8-methylquinoline-3-carbaldehyde

The quinoline fused-ring system of the title compound, C11H8ClNO, is planar (r.m.s. deviation = 0.005 Å); the formyl group is slightly bent out of the plane [C-C-C-O1 torsion angles = 8.8 (7) and -172.8 (4)°].

6,8-Dibromo-5-hydroxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate

In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) angstrom]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)degrees. The crystal structure is stabilized by intermolecular C-H center dot center dot center dot O interactions and an intramolecular O-H center dot center dot center dot O hydrogen bond also occurs.

3D hierarchical rutile TiO2 and metal-free organic sensitizer producing dye-sensitized solar cells 8.6% conversion efficiency

Three-dimensional (3D) hierarchical nanoscale architectures comprised of building blocks, with specifically engineered morphologies, are expected to play important roles in the fabrication of 'next generation' microelectronic and optoelectronic devices due to their high surface-to-volume ratio as well as opto-electronic properties. Herein, a series of well-defined 3D hierarchical rutile TiO2 architectures (HRT) were successfully prepared using a facile hydrothermal method without any surfactant or template, simply by changing the concentration of hydrochloric acid used in the synthesis. The production of these materials provides, to the best of our knowledge, the first identified example of a ledgewise growth mechanism in a rutile TiO2 structure. Also for the first time, a Dye-sensitized Solar Cell (DSC) combining a HRT is reported in conjunction with a high-extinction-coefficient metal-free organic sensitizer (D149), achieving a conversion efficiency of 5.5%, which is superior to ones employing P25 (4.5%), comparable to state-of-the-art commercial transparent titania anatase paste (5.8%). Further to this, an overall conversion efficiency 8.6% was achieved when HRT was used as the light scattering layer, a considerable improvement over the commercial transparent/reflector titania anatase paste (7.6%), a significantly smaller gap in performance than has been seen previously.