Reactivity of ammonium chloride/mercuric chloride mixtures with monel containers. The new compounds (NH4)(2)(NH3)(x)[Ni(NH3)(2)Cl-4] and (NH4)(5)Cl-2[CuCl2][CuCl4]

Ammonium chloride/mercuric chloride mixtures (molar ratio 2: 1) react at 350degreesC with Monel (Cu68Ni32) to yield (NH4)NiCl3 and mercury and copper amalgam, respectively. With larger amounts of (NH4)Cl in the reaction mixture, dark green (NH4)(2)(NH3)(x)[Ni(NH3)(2)Cl-4] (x approximate to 0.77) (1) is also formed as a main product. Light blue crystals of the mixed-valent copper(I,II) chloride (NH4)(5)Cl-5[CuCl2][CuCl4] (2) were obtained as a minor byproduct from a 4:1 reaction mixture. The crystal structures were determined from single crystal X-ray data; (1): tetragonal, I4/mmm, a = 770.9(1), e = 794.2(2) pm, 190 reflections, R-1 = 0.0263; (2): tetragonal, I4/mcm, a = 874.8(1), c = 2329.2(3) pm, 451 reflections, R-1 = 0.0736. In (1) Ni2+ resides in trans-[Ni(NH3)(2)Cl-4](2-) octahedra, and in (2) copper(l) is linearly two-coordinated in ECUC121- and copper(II) resides in a flattened tetrahedron [CuCl4](2-) with a tetrahedricity of 89%. (C) 2001 Elsevier Science.

Observations on the mechanism of eggshell formation in the liver fluke, Fasciola hepatica

A mechanism for eggshell production in Schistosoma mansoni has been proposed (Wells & Cordingley, 1991), and suggests that the release of eggshell protein globules from the vitelline cells occurs under alkaline conditions within the ootype followed by their subsequent fusion to form the eggshell. Fusion and tanning of these components produces eggshell which autofluoresces. The present study was carried out to determine whether a similar process operates in Fasciola hepatica. A number of drug treatments were used to disrupt key steps in the maturation of vitelline cells. Treatment with the calcium ionophore lasalocid (1 x 10(-5) M) led to the premature release of eggshell globules from the vitelline cells but not their fusion. Incubation in monensin (1 x 10(-6) M), a sodium ionophore and ammonium chloride (NH4Cl) (5 x 10(-2) M), a weak base, resulted in the premature fusion of eggshell protein globules within the vitelline cells and premature tanning of the eggshell protein material. The copper-containing enzyme, phenol oxidase, is thought to be involved in the tanning process during the production of eggs. Diethyldithiocarbamate (DDC, 1 x 10(-3) M) is a phenol oxidase inhibitor and treatment with this compound, in combination treatments with monensin and NH4Cl, prevented fusion of the vitelline cell globules and tanning of the shell protein material. The results of the study suggest that the mechanism for eggshell formation in F. hepatica is similar to that proposed for S. mansoni and may be common to other trematodes as well.

Hierarchical zeolites prepared by organosilane templating: A study of the synthesis mechanism and catalytic activity

The crystallization of hierarchical ZSM-5 in the presence of the organosilane octadecyl-dimethyl-(3-trimethoxysilyl-propyl)-ammonium chloride as the mesoporogen was investigated as a function of time and temperature. The synthesis by this method proceeds in two steps. The rapid formation of a predominantly amorphous disordered mesoporous aluminosilicate precursor phase is followed by the formation of globular highly mesoporous zeolite particles involving dissolution of the precursor phase. It is difficult to completely convert the initial phase into the final hierarchical zeolite. This limits the amount of aluminium built into the MFI network and the resulting Bronsted acidity. In the presence of iron, more crystalline hierarchical zeolite is obtained. These Fe-containing zeolites are excellent catalysts for the selective oxidation of benzene to phenol. Their hierarchical pore structure leads to higher reaction rates due to increased mass transfer and increased catalyst longevity despite more substantial coke formation. (C) 2011 Elsevier B.V. All rights reserved.

Encapsulation of phase change materials using rice-husk-char

This paper explored a new approach to prepare phase change microcapsules using carbon-based particles via Pickering emulsions for energy storage applications. Rice-husk-char, a by-product in biofuel production, containing 53.58 wt% of carbon was used as a model carbon-based material to encapsulate hexadecane. As a model phase change material, hexadecane was emulsified in aqueous suspensions of rice-husk-char nanoparticles. Water soluble polymers poly(diallyldimethyl-ammonium chloride) and poly(sodium styrene sulfonate) were used to fix the rice-husk-char nanoparticles on the emulsion droplets through layer-by-layer assembly to enhance the structural stability of the microcapsules. The microcapsules formed are composed of a thin shell encompassing a large core consisting of hexadecane. Thermal gravimetrical and differential scanning calorimeter analyses showed the phase change enthalpy of 80.9 kJ kg−1 or 120.0 MJ m−3. Design criteria of phase change microcapsules and preparation considerations were discussed in terms of desired applications. This work demonstrated possible utilisations of biomass-originated carbon-based material for thermal energy recovery and storage applications, which can be a new route of carbon capture and utilisation.

Ionic Liquid-Based Routes to Conversion or Reuse of Recycled Ammonium Perchlorate

New, potentially green, and efficient synthetic routes for the remediation and/or re-use of perchlorate-based energetic materials have been developed. Four simple organic imidazolium- and phosphonium-based perchlorate salts/ionic liquids have been synthesized by simple, inexpensive, and nonhazardous methods, using ammonium perchlorate as the perchlorate source. By appropriate choice of the cation, perchlorate can be incorporated into an ionic liquid which serves as its own electrolyte for the electrochemical reduction of the perchlorate anion, allowing for the regeneration of the chloride-based parent ionic liquid. The electrochemical degradation of the hazardous perchlorate ion and its conversion to harmless chloride during electrolysis was studied using IR and Cl-35 NMR spectroscopies.

Ca2+- and volume-sensitive chloride currents are differentially regulated by agonists and store-operated Ca2+ entry.

Using patch-clamp and calcium imaging techniques, we characterized the effects of ATP and histamine on human keratinocytes. In the HaCaT cell line, both receptor agonists induced a transient elevation of [Ca2+]i in a Ca2+-free medium followed by a secondary [Ca2+]i rise upon Ca2+ readmission due to store-operated calcium entry (SOCE). In voltage-clamped cells, agonists activated two kinetically distinct currents, which showed differing voltage dependences and were identified as Ca2+-activated (ICl(Ca)) and volume-regulated (ICl, swell) chloride currents. NPPB and DIDS more efficiently inhibited ICl(Ca) and ICl, swell, respectively. Cell swelling caused by hypotonic solution invariably activated ICl, swell while regulatory volume decrease occurred in intact cells, as was found in flow cytometry experiments. The PLC inhibitor U-73122 blocked both agonist- and cell swelling–induced ICl, swell, while its inactive analogue U-73343 had no effect. ICl(Ca) could be activated by cytoplasmic calcium increase due to thapsigargin (TG)-induced SOCE as well as by buffering [Ca2+]i in the pipette solution at 500 nM. In contrast, ICl, swell could be directly activated by 1-oleoyl-2-acetyl-sn-glycerol (OAG), a cell-permeable DAG analogue, but neither by InsP3 infusion nor by the cytoplasmic calcium increase. PKC also had no role in its regulation. Agonists, OAG, and cell swelling induced ICl, swell in a nonadditive manner, suggesting their convergence on a common pathway. ICl, swell and ICl(Ca) showed only a limited overlap (i.e., simultaneous activation), although various maneuvers were able to induce these currents sequentially in the same cell. TG-induced SOCE strongly potentiated ICl(Ca), but abolished ICl, swell, thereby providing a clue for this paradox. Thus, we have established for the first time using a keratinocyte model that ICl, swell can be physiologically activated under isotonic conditions by receptors coupled to the phosphoinositide pathway. These results also suggest a novel function for SOCE, which can operate as a "selection" switch between closely localized channels.

Ca2+ current and Ca(2+)-activated chloride current in isolated smooth muscle cells of the sheep urethra.

1. Isolated sheep urethral cells were studied using the perforated patch clamp technique (T = 37 degrees C). Depolarizing steps ranging from -40 to -10 mV evoked an inward current that peaked within 10 ms and a slower inward current. Stepping back to the holding potential of -80 mV evoked large inward tail currents. All three currents were abolished by nifedipine (1 microM). Substitution of external Ca2+ with Ba2+ resulted in potentiation of the fast inward current and blockade of the slow current and tails. 2. Changing the chloride equilibrium potential (ECl) from 0 to +27 mV shifted the reversal potential of the tail currents from 1 +/- 1 to 27 +/- 1 mV (number of cells, n = 5). Chloride channel blockers, niflumic acid (10 microM) and anthracene-9-carboxylic acid (9AC, 1 mM), reduced the slow current and tails suggesting that these were Ca(2+)-activated Cl- currents, ICl(Ca). 4. Caffeine (10 mM) induced currents that reversed at ECl and were blocked by niflumic acid (10 microM). 5. In current clamp mode, some cells developed spontaneous transient depolarizations (STDs) and action potentials. Short exposure to nifedipine blocked the action potentials and unmasked STDs. In contrast, 9AC and niflumic acid reduced the amplitude of the STDs and blocked the action potentials. 6. In conclusion, these cells have both L-type ICa and ICl(Ca). The former appears to be responsible for the upstroke of the action potential, while the latter may act as a pacemaker current.

Monitoring electrical resistance of concretes containing alternative cementitious materials to assess their resistance to chloride penetration

This is an invited contribution in a special issue of the Journal of Cement and Concrete Composites

'PERMIT' ion migration test for measuring the chloride ion transport of concrete on site

The ingress of chlorides into concrete is predominantly by the mechanism of diffusion and the resistance of concrete to the transport of chlorides is generally represented by its coefficient of diffusion. The determination of this coefficient normally requires long test duration (many months). Therefore, rapid test methods based on the electrical migration of ions have widely been used. The current procedure of chloride ion migration tests involves placing a concrete disc between an ion source solution and a neutral solution and accelerating the transport of ions from the source solution to the neutral solution by the application of a potential difference across the concrete disc. This means that, in order to determine the chloride transport resistance of concrete cover, cores should be extracted from the structure and tested in laboratories. In an attempt to facilitate testing of the concrete cover on site, an in situ ion migration test (hereafter referred to as PERMIT ion migration test for the unique identification of the new test) was developed. The PERMIT ion migration test was validated in the lab by carrying out a comparative investigation and correlating the results with the migration coefficient from the one-dimensional chloride migration test, the effective diffusion coefficient from the normal diffusion test and the apparent diffusion coefficient determined from chloride profiles. A range of concrete mixes made with ordinary Portland cement was used for this purpose. In addition, the effects of preferential flow of ions close to the concrete surface and the proximity of reinforcement within the test area on the in situ migration coefficients were investigated. It was observed that the in situ migration index, found in one working day, correlated well with the chloride diffusion coefficients from other tests. The quality of the surface layer of the cover concrete and the location of the reinforcement within the test area were found to affect the flow of ions through the concrete during the test. Based on the data, a procedure to carry out the PERMIT ion migration test was standardised.