Synthesis and Characterization of Optical Sol–Gel Adhesive for Military Protective Polycarbonate Resin

Sol–gel adhesive material for isostatic hotpressing lamination process was synthesized using 3-aminopropyltrimethoxysilane (APTES), 3-glycidyloxypropyltrimethoxysilane (GPTS) and methacryloxypropyltrimethoxysilane (MPTS) as precursors. Reaction dynamics between APTES and GPTS was followed on-line with Raman spectroscopy. The lamination process was optimized by varying hotpressing times and pressures at the constant temperature. Mechanical shear strength properties were found to be excellent for studied composition, 25–30 kg/cm² at its best. One possible application of laminated polycarbonate (PC) structure is a soldier helmet visor. Therefore, the ballistic protection properties were tested by shooting with 1.1 gram standard fragment, and determining the v₅₀ velocity value, which corresponds to 50% perforation. The laminated structure gave 5.7% better protection compared with the solid polycarbonate. The laminated components were found to have high optical transparency at the visible wavelengths as well as high environmental stability.     

The influence of the salt concentration on the aggregation behavior of viscoelastic detergents

The influence of excess NaCl on the properties of viscoelastic detergent solutions of Cetypyridiniumsalicylate (CPySal) has been studied by static and dynamic light scattering, electric birefringence and rheological measurements. It is obeserved that the rodlike micelles of length L which are present in these solutions and which are responsible for their elastic properties grow in length with the increase of the NaCl concentration. As long as the rods are shorter than their mean distance, their length can be determined from the rheological and electric birefringence measurements. For very small shear fields these solutions behave as Newtonian fluids. The viscosity of the solution increases strongly when the rods begin to overlap. Solutions with overlapping rods are elastic. It is postulated from the results that the cmc_II (the critical concentration above which rods are present) and the length L of the rods are partially determined by the intermicellar interaction energy. It is furthermore postulated that this intermicellar interaction energy has an influence on the polydispersity of the rods and seems to make the rods relatively monodisperse.     

Synthesis and characterization of the non-Kekulé, singlet biradicaloid Ar'Ge(micro-NSiMe(3))(2)GeAr' (Ar' = 2,6-Dipp(2)C(6)H(3), Dipp = 2,6-i-Pr(2)C(6)H(3))

Reaction of Ar'GeGeAr' (1) with an excess of Me3SiN3 gives the non-Kekulé, biradicaloid Ar'Ge(mu-NSiMe3)2GeAr' (3, Ar' = 2,6-Dipp2C6H3, Dipp = 2,6-i-Pr2C6H3) which has a planar Ge2N2Si2 array and pyramidal geometry at the germaniums. DFT calculations for the model MeGe(mu-NSiH3)2GeMe indicate no Ge-Ge bonding and a singlet ground state. The calculated energy difference between the optimized singlet and triplet states is 17.51 kcal/mol.     

Chemical analysis of rain and snow samples from Chernogolovk/Russia by IC, TXRF and ICP–MS

 Data are reported for a first measurement campaign for a great number of cations (the range of concentrations for main components is given in ng/mL: Na:<70–880; Mg: 12–160; Al:<7–120; K: 200–1600; NH₄ ⁺: 2500–9000; Ca: 300–2500; Fe:<140–1200; Zn: 20–320) and anions (HCOO^-: 100–1800; CH₃COO^-: 400–14500; C₂O^2- ₄: <100–460; NO^- ₂: <20–55; NO^- ₃: 660–9900; SO^2- ₃:<100–1150; SO₄ ^2-: 450–19700; Cl^-: 170–3200) in rain and snow samples of the Chernogolovka region 80 km northeast of the centre of Moscow. These data serve as a first assessment of the situation of the atmosphere in this region. For the determination of fluoride, formate, acetate, nitrite, bromide, nitrate, sulfite, and sulfate by IC, a relevant development of the method was carried out. For some metallic cations, a critical quality control was achieved by parallel measurements with ICP-MS, TXRF, and IC. Furthermore, time resolved measurements were performed for a rain event. Filtration experiments were undertaken to differentiate between the presence of a series of elements and species in liquid or solid state in the collected aqueous samples. Received: 25 July 1996 / Revised: 26 September 1996 / Accepted: 13 October 1996     

Is laser-ablation-ICP-MS an alternative to solution analysis of solid samples?

The basic obstacles for the general use of laser-ablation(LA)-ICP-MS in analytical laboratories are connected with its reproducibility and calibration. A mathematical relation deduced from the correlation function of the analytical signals allows the estimation of the number of craters needed for representative analyses. The procedure was applied to different samples such as manganese crusts and soils. The ion intensities of the major elements in the manganese crusts and nodules were used as internal standards, improving relative standard deviations by factors between 2 and 3. Selected samples of wood and manganese crusts were analyzed by LA-ICP-MS and the results compared with those obtained by solution ICP-MS. The agreement of the values is within the 95% confidence limits. Powdered reference materials and, in the case of wood analysis, cellulose doped with standard solutions were used for the calibration.     

Vesicle Phases with Semipolar Additives

We examined the influence of semipolar additives on the phase behavior of mixed zwitterionic surfactant/consurfactant systems. It is shown that in these systems with increasing concentration esters like hexylacetate (HA) and ketones like hexylmethylketone (HMK) can behave both like consurfactants and like hydrocarbons. In solutions of 200 mM tetradecyldimethylamineoxide (TDMAO)/cosurfactant the additives cause first a phase transformation from the micellar L(1) phase to a lamellar L(alpha) phase. Upon further increasing concentration, the L(alpha) phase is transformed into a microemulsion. The L(alpha) phase consists of densely packed multilamellar vesicles. The vesicles are shown by electron microscopy. The multilamellar character of the vesicles is also reflected in the conductivity of the phase. It is up to 10 times lower than the conductivity of the L(1) phase. In some systems the vesicles are transformed on rest into a multidomain stacked L(alpha) phase. It is furthermore demonstrated that the two-phase L(1)/L(alpha) region in these systems is very narrow. In situations where enough HA is added to be close to the boundary of the L(1) phase, it is shown that very small amounts of cosurfactant can transform the L(1) phase into the L(alpha) phase. In extreme situations 1 mM cosurfactant is sufficient for transforming the L(1) phase with 200 mM TDMAO into the L(alpha) phase. In the investigated systems the L(alpha) phase is a highly viscoelastic fluid in which the storage modulus is 1 order of magnitude larger than the loss modulus. Besides the conventional way to prepare samples by adding all ingredients and stirring the solution intensively, all investigated systems were additionally prepared without applying any shear forces. In a surfactant/cosurfactant solution the additive was brought into the sample by diffusion. The phase behavior of both types of samples showed fundamental differences in some cases, which give insight into the influence of shear forces on these systems. Copyright 2001 Academic Press.     

Multiplex polymerase chain reaction analysis of Glu-1 high-molecular-mass glutenin genes from wheat by capillary electrophoresis with laser-induced fluorescence detection

The unique bread-making properties of wheat are closely correlated with composition and quantity of high-molecular-mass (HMW) glutenin subunits encoded by the Glu-1 genes. We report the development of a multiplex polymerase chain reaction (PCR) method to identify bread wheat genotypes carrying HMW glutenin allele composition of Glu-1 complex loci (Glu-A1, Glu-B1 and Glu-D1) by capillary electrophoresis(CE) with laser-induced fluorescence (LIF) detection. Two triplex primer sets of HMW glutenin subunit genes were examined. An automated and rapid CE-LIF technique is helpful in the multiplex PCR optimization process. Two fluorescent intercalating dyes (EnhanCE, and YO-PRO-1) are compared for detection of DNA fragments. Amplified DNA fragments of HMW glutenin Glu-1 genes were well separated both by agarose slab-gel electrophoresis and CE, and revealed minor differences between the sequences of 1Ax2*, 1Axnull, 1Bx6, 1Bx7, 1Bx17 and 1Dx5 genes. Moreover, CE technique requires samples of smaller volumes in comparison to slab-gel electrophoresis, and data can be obtained in less than 20 min. There was a very high concordance in the assessment of the molecular size of PCR-generated DNA markers. Fast and accurate identification of molecular markers of Glu-1 genes by CE-LIF can be an efficient alternative to standard procedure separation for early selection of useful wheat genotypes with good bread-making quality.     

Spectrum analysis of U-doped LaBr3 single crystals. Part 1: crystal-field analysis

Single crystals of U³⁺:LaBr₃ were grown by the Bridgman-Stockbarger technique. High-resolution polarized absorption spectra of the crystals were recorded at 4.2 K in the 4000-50,000 cm⁻¹ range. Sixty-four experimental crystal-field energy levels of the U³⁺ ion were fitted to a semiempirical Hamiltonian employing free-ion, one-electron crystal-field as well as two-particle correlation crystal-field (CCF) operators with an r.m.s. deviation of 28 cm⁻¹. The performed analysis of the spectra enabled the determination of crystal-field parameters and assignment of the observed 5f³→5f³ transitions. The effects of selected CCF operators on the splitting of some specific U³⁺ multiplets have been investigated and the obtained values of Hamiltonian parameters are discussed and compared with those reported in previous analyses.     

Die Verteilungkoeffizienten von TiO2+, Cr3+, Mn2+ und Fe3+

Ohne Zusammenfassung     

Fluorous,chromatography-free Mitsunobu reaction

[formula: see text] The reaction of secondary and primary alcohols with highly fluorinated 3,4,5-tris(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan- 1-yloxy)benzoic acid in the presence of Ph3P and DIAD in THF at room temperature (fluorous Mitsunobu) resulted in a simple, chromatography-free isolation protocol with excellent yields (83-96%).