Argon plasma transport properties at reduced pressures

Argon plasma transport properties at low pressures (0.01 atm) are calculated using a modified Debve length suggested by T. Kihara et al. Electrons and heavy species are treated as two different gases, and the method of calculation is based on the simplified theory (or transport properties developed by R. S. Devoto. A generalized Saha equation is used to calculate the species composition, and experimental data by Y. Itikawa for momentum transfer cross sections are adapted for the evaluation of electron-atom collision cross sections.     

GC and MS Properties of β-Blockers as tert-Butyldimethylsilyl Derivatives and as Ethoxycarbonyl/Trimethylsilyl Derivatives

Fourteen β-blockers in pre-dried free base forms were simultaneously converted into tert-butyldimethylsilyl (TBDMS) derivatives in one-step. As a different approach, β-blockers were directly transformed into N-ethoxycarbonyl (EOC) derivatives in aqueous solution, followed by extraction and trimethylsilyl (TMS) derivatization. The retention index sets measured by DB-5 and DB-17 dual-column GC were characteristic for each β-blocker as TBDMS- and EOC/TMS derivatives. Their characteristic fragmentation patterns obtained by GC–MS facilitated easier peak identification of each β-blocker. The overall EOC/TMS method for assays of 14 β-blockers in aqueous solution was linear with acceptable precision and accuracy.     

Dynamic and redox active pillared bilayer open framework: single-crystal-to-single-crystal transformations upon guest removal, guest exchange, and framework oxidation

A metal-organic pillared bilayer open framework having 3D channels, [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).6C(5)H(5)N.36H(2)O (BOF-1, 1), has been assembled from bismacrocyclic nickel(II) complex [Ni(2)(C(26)H(52)N(10))(Cl)(4)].H(2)O and sodium 1,3,5-benzenetricarboxylate (Na(3)BTC). The channels are occupied by pyridine and water guest molecules. When the single crystal of 1 was dried in air and then heated at 75 degrees C for 1.5 h, respectively, [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).30H(2)O (1') and [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).4H(2)O (2) resulted with retention of the single crystallinity. The X-ray structures reveal spongelike dynamic behavior of the bilayer framework that reduces the interlayer distance in response to the amount of guest molecules. Solid 2 differentiates various alcohols. When 1 was immersed in pyridine and benzene, guest molecules were exchanged with retention of the single-crystal nature to give rise to [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).20pyridine.6H(2)O (3) and [Ni(2)(C(26)H(52)N(10))](3)[BTC](4).14benzene.19H(2)O (4), respectively. Furthermore, crystal 1 reacted with I(2) via single-crystal-to-single-crystal transformation to produce [Ni(2)(C(26)H(52)N(10))](3)[C(9)H(3)O(6)](4)(I(3))(4).nI(2).17H(2)O (5) that consists of positively charged framework incorporating nickel(III) and nickel(II) ions and the channels including I(3)(-) and I(2).     

Boosting Electrochemical Water Oxidation with Metal Hydroxide Carbonate Templated Prussian Blue Analogues

The development of efficient and stable catalyst systems with low‐cost, abundant, and non‐toxic materials is the primary demand for electrochemical water oxidation. A unique method is reported for the syntheses of metal hydroxide carbonate templated Prussian blue analogues (PBAs) on carbon cloth and their outstanding water oxidation activities in alkaline medium. The best water oxidation activity is obtained with cobalt hydroxide carbonate templated t‐Co^II‐Co^III with an overpotential as low as 240 mV to reach a current density of 10 mA cm^?2. It produces constant current over 50 h in chronoamperometric measurements. Moreover, the catalysts outperform the activities of the PBAs prepared without any template and even the noble metal catalyst RuO₂. Spectroscopic and microscopic studies show that the PBAs are transformed into layered hydroxide–oxyhydroxide structures during electrochemical process and provide the active sites for the water oxidation.     

Flexible eightfold interpenetrating diamondoid network generating 1D channels: selective binding with organic guests

An 8-fold interpenetrating diamondoid network, [Ni(cyclam)]2[TCM]. 2DMF x 10H2O, has been prepared by the self-assembly of a Ni-(II)cyclam macrocyclic complex and sodium tetrakis[4-(carboxyphenyl)-oxamethyl]methane in DMF/water. The network shows an unusual [4 + 4] mode of interpenetration, generating 1D channels of effective window size 6.7 A x 4.7 A. The network shows flexible behavior: it becomes nonporous on removal of the guest molecules occupying the channels, but the open structure is restored when the desolvated solid is immersed in the mixture of H2O/DMF (1:1, v/v) for 5 min. The desolvated host has different binding capacities for n-butanol, pyridine, and ethanol.     

Modeling of the plasma sintering process at reduced pressures

Numerical simulation of the thermal behavior of sintering specimen under RF plasma conditions at reduced pressure is considered. A two-dimensional approach is adopted for describing flow, temperature, and electromagnetic fields in the reactor with appropriate boundary conditions. Slip boundary conditions are imposed for the velocity field at the sample surface and at the wall of the reactor, and corresponding jump boundary conditions are specified for the temperature field. Simple kinetic theory is employed for the calculation of the heat flux from the plasma to the specimen. The so-called capture-radiative-cascade model is adopted for ionization and recombination processes. The results indicate that ion-electron surface recombination is the dominant heat transfer mechanism to the sintering specimen under reduced pressure conditions.     

Electrowetting-based droplet mixers for microfluidic systems

Mixing of analytes and reagents is a critical step in realizing a lab-on-a-chip. However, mixing of liquids is very difficult in continuous flow microfluidics due to laminar flow conditions. An alternative mixing strategy is presented based on the discretization of liquids into droplets and further manipulation of those droplets by electrowetting. The interfacial tensions of the droplets are controlled with the application of voltage. The droplets act as virtual mixing chambers, and mixing occurs by transporting the droplet across an electrode array. We also present an improved method for visualization of mixing where the top and side views of mixing are simultaneously observed. Microliters of liquid droplets are mixed in less than five seconds, which is an order of magnitude improvement in reported mixing times of droplets. Flow reversibility hinders the process of mixing during linear droplet motion. This mixing process is not physically confined and can be dynamically reconfigured to any location on the chip to improve the throughput of the lab-on-a-chip.     

Determination of fluorine by PIGE analysis on bovine tooth enamel treated with bamboo salt SMFP toothpaste and fluoride mouth rinsing solution

The purpose of this study was to evaluate the effectiveness of a toothpaste containing bamboo salt on fluorine uptake in bovine enamel and to compare the efficiency of fluorine uptake between sodium monofluorophosphate (SMFP) toothpaste and sodium fluoride (NaF) mouthrinsing solution using proton induced -ray emission analysis. 30 bovine tooth enamel specimens were prepared and assigned to 5 groups as follows: (a) specimens without any treatment, (b) specimens which were treated with a toothpaste containing dicalcium phosphate dihydrate (DCPD) only, (c) specimens which were treated with a toothpaste containing DCPD and SMFP, (d) specimens which were treated with a toothpaste containing DCPD, SMFP and 2% bamboo salt, (e) specimens which were treated with 0.05% NaF mouthrinsing solution. After 5 and 10 hours of treatment, fluorine concentration was measured at the depth of 263, 625, 2530 nm from the surface of the specimens. The surface concentration of fluorine was markedly increased using SMFP dentifrice. Bamboo salt did not encourage the uptake of fluorine into the enamel surface. NaF mouthrinsing solution showed a considerably higher uptake of fluoride in the intact enamel surface than the SMFP dentifrices.     

N-ethoxycarbonylation combined with (S)-1-phenylethylamidation for enantioseparation of amino acids by achiral gas chromatography and gas chromatography-mass spectrometry

N-ethoxycarbonylation was combined with (S)-1-phenylethylamidation for enantioseparation of amino acids by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) on achiral capillary columns. The method provided complete enantioseparations of 12 amino acids as diastereomeric N-ethoxycarbonyl/(S)-1-phenylethylamides with exceptional resolutions for proline (R(s) > or = 9.9) and pipecolic acid (R(s) > or = 10.2). GC-MS analysis in selected ion monitoring mode employing standard addition method, facilitated quantitation of D-pipecolic acid in kidney bean (0.95 microg/10 mg) and adzuki bean (0.14 microg/10 mg). The peak area ratios indicated that they had the identical chiral composition at 2.5% for D-pipecolic acid and 97.5% for L-pipecolic acid.