Ammonium Hydroxide Solution Research Articles

Preparation of Uric Acid Standard Stock Solution

For measurement of uric acid in serum, calibrators of known concentration must be prepared in a suitable solvent. Uric acid is virtually insoluble in water or common organic solvents, but it can be dissolved in basic solution such as aqueous solutions of Li2CO3 (1), KOH (2), NaOH(3), and ammonium hydroxide (4)(5). Siekmann(4) used …

Zirconium Titanate: Synthesis and Processing of Fine Powders Prepared by Chemical Route

A process for synthesis of fine zirconium titanate powders by chemical route is described. Zirconium/titanium molar ratio was varied from 0.67 to 1.5 and the powders produced were analyzed. The precipitation process comprises the mixture of zirconium and titanium metal salt solutions to ammonium hydroxide solution, followed by washing of the precipitate, calcination and grinding to result in zirconium titanate. The ceramic powder is then uniaxially pressed as cylindrical samples and sintered at 1400°C for 5 hours. The microstructure of fractured and thermally etched ceramic was observed by scanning electron microscopy, and crystal phase identifications were done by X-ray diffraction. At least two different zirconium titanate phases, ZrTiO4 and Zr5Ti7O24, were identified. Ceramic hardness was measured by Vickers indentation.

Validation of the LC-MS/MS method for the quantification of mevalonic acid in human plasma and determination of the matrix effect

A simple, specific, and sufficiently sensitive liquid chromatography-tandem mass spectrometry (negative-ion electrospray ionization) methodology to determine mevalonic acid (MVA) in human plasma is described, and its application to the analysis of rat plasma MVA levels after rosuvastatin administration is demonstrated. The method was validated over the linearity range of 0.5-50.0 ng/ml (r(2) > 0.99) using deuterated MVA as an internal standard. The lower limit of quantification was 0.5 ng/ml. The assay procedure involved the isolation of MVA from plasma samples using solid-phase extraction. Chromatographic separation was achieved on a HyPurity Advance column with a mobile phase consisting of ammonium formate buffer (10 mM, pH 8.0) and acetonitrile (70:30, v/v). Excellent precision and accuracy were observed. MVA and deuterated mevalonolactone were stable in water and plasma under different storage and processing conditions. The recovery observed was low, which was attributable to a significant matrix effect. A significant decrease (30-40%; P < 0.05) was observed in rat plasma MVA levels after rosuvastatin administration.

Poly(methyl methacrylate) as masking material for microelectromechanical system (MEMS) fabrication

AbstractIn the present study direct current (dc) sputtered poly(methyl methacrylate) (PMMA) films deposited on silicon substrates were evaluated as masking materials for anisotropic etching of silicon in aqueous potassium hydroxide (KOH) and tetramethyl ammonium hydroxide (TMAH) solutions. Sputtered PMMA films were characterized by FTIR to ascertain the bonding, by X‐ray photoelectron spectroscopy (XPS) for the elemental composition, and by the contact angle for measuring the adhesion of the film with the substrate. FTIR and XPS data showed the presence of a poly(tetrafluoroethylene)‐like film on the silicon substrate. The interfacial tension was calculated from the contact angle value, which was 0.82 dyne/cm, confirming good adhesion of the film and the substrate. A pattern was lithographically transferred through the masking material on the silicon substrate, and the etch rate of the masking layer was calculated from the masking time data of the films. The etch rate value of 4 Å/min obtained for the masking material is low compared to the etch rate of the conventional masking materials (60 Å/min for SiO2 and 8 Å/min for Si3N4). © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2094–2098, 2006

A chemically amplified positive-working photosensitive polyimide based on a blend of poly(amic acid ethoxymethyl ester) and poly(amic acid)

We prepared a novel chemically amplified photosensitive polyimide based on a blend of poly(amic acid ethoxymethyl ester) (PAAE) and poly(amic acid); this blend produces polyimide (PI) films with improved mechanical properties after imidization with photoacid generator (PAG). PAAE and poly(amic acid) were end-capped with 5-norbornene-2,3-dicarboxylic dianhydride and 2,3-dimethyl maleic anhydride, respectively, to lower their molecular weights without compromising the properties of the resulting PI films. As a result of the blending of these PI precursors, the mechanical properties of the PI films were found to be less affected by the strong acid generated from the PAG than PI films fabricated by imidization of PAAE alone. The relatively high solubility of the blended PI precursor film in basic aqueous solutions was found to be effectively controlled by the use of a high-temperature post-exposure bake process to partially imidize the end-capped PAA. It was found that a 10-μm-thick film of the PSPI precursor system containing 13 wt% PAGs exhibits a sensitivity ( D 0) of 700 mJ/cm 2 when developed with 2.38 wt% aqueous tetramethyl ammonium hydroxide solution at room temperature. A fine positive pattern was fabricated in a 12 μm thick film with 1000 mJ/cm 2 of i-line exposure. The resultant PI film was also found to exhibit excellent mechanical and thermal properties, which are critical to its practical use as a stress buffer layer in semiconductor packaging.

One-pot preparation of silica-supported hybrid immobilized metal affinity adsorbent with macroporous surface based on surface imprinting coating technique combined with polysaccharide incorporated sol–gel process

A simple and reliable one-pot approach using surface imprinting coating technique combined with polysaccharide incorporated sol–gel process was established to synthesize a new organic–inorganic hybrid matrix possessing macroporous surface and functional ligand. Using mesoporous silica gel being a support, immobilized metal affinity adsorbent with a macroporous shell/mesoporous core structure was obtained after metal ion loading. In the prepared matrix, covalently bonded coating and morphology manipulation on silica gel was achieved by using one-pot sol–gel process starting from an inorganic precursor, <gamma>-glycidoxypropyltrimethoxysiloxane (GPTMS), and a functional biopolymer, chitosan (CS) at the atmosphere of imprinting polyethylene glycol (PEG). Self-hydrolysis of GPTMS, self-condensation, and co-condensation of silanol groups (Si-OH) from siloxane and silica gel surface, and in situ covalent cross-linking of CS created an orderly coating on silica gel surface. PEG extraction using hot ammonium hydroxide solution gave a chemically and mechanically stabilized pore structure and deactivated residual epoxy groups. The prepared matrix was characterized by using X-ray energy dispersion spectroscopy (EDX), scanning electron microscopy (SEM) and mercury intrusion porosimetry. The matrix possessed a high capacity for copper ion loading. Protein adsorption performance of the new immobilized metal affinity adsorbent was evaluated by batch adsorption and column chromatographic experiment using bovine serum albumin (BSA) as a simple model protein. Under the optimized coating conditions, the obtained macroporous surface resulted in a fast kinetics and high capability for protein adsorption, while the matrix non-charged with metal ions offered a low non-specific adsorption.

Change in high field Q-slope by baking and anodizing

Low temperature RF performance of two niobium cavities that underwent different chemical treatments was measured after they were heat treated at 100 °C for 48 h. After heat treatment cavities were anodized in ammonia hydroxide solution for sequentially increasing voltage until baking effect was gone. The thickness of niobium finally consumed is estimated to be 20 nm. The results are discussed in view of one of the current models for the baking effect on the high field Q-slope.

Mechanisms of Macronutrient Deficiency and Associated Clinical Conditions

Eleutheroside B and Eleutheroside E, two kinds of the major bioactive saponins of Eleutherococcus senticosus, play a pivotal role in biologic activity. In this study, a specific and sensitive high performance liquid chromatography–electrospray ionization-tandem mass spectrometry method (HPLC–MS/MS) was developed and validated for simultaneous determination of Eleutheroside B and Eleutheroside E in rat plasma. The analytes were extracted from rat plasma via a simple protein precipitation procedure with methanol and polygonin was used as internal standard. Chromatographic separation was achieved on a C18 column using a gradient elution program with acetonitrile and water containing 0.1% ammonium hydroxide solution as the mobile phase, with a flow rate of 0.2 mL/min. The detection was performed on a triple–quadrupole tandem mass spectrometer by multiple reactions monitoring (MRM) mode in a negative ion mode via electrospray ionization (ESI). The transition monitored were m/z 371 [M−H]− → 209 for Eleutheroside B, m/z 741[M−H]− → 579 for Eleutheroside E and m/z 389[M−H]− → 277 for internal standard. Linear calibration curves were obtained in the concentration range of 1–2000 ng/mL for both (Eleutheroside B and Eleutheroside E), with a lower limit of quantification of 1 ng/mL. Extraction recovery was over 80% in plasma. The intra- and inter-day precision (RSD) values were below 12% and accuracy (RE) was −2.80 to 5.70% at three QC levels for both. The assay was successfully applied to study pharmacokinetics behavior in rats after oral and intravenous administration of the single substances (Eleutheroside B and Eleutheroside E). And further research was performed by comparing the difference in pharmacokinetic behavior between the single substances and an aqueous extract of E. senticosus after oral administration. Significant difference in pharmacokinetic characteristics between the single substances and an aqueous extract was found in rat, which would be beneficial for the pre-clinical research and clinical use of E. senticosus.

A coprecipitation technique to prepare NaNbO3 and NaTaO3

A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO3 (NN) and NaTaO3 (NT). An alcoholic solution of ammonium carbonate and ammonium hydroxide was used to precipitate Na+ and Nb5+ (or Ta5+) cations under basic conditions as carbonate and hydroxide, respectively. On heating at 700°C, these precursors produce respective products. For comparison, both NN and NT powders were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). The particle size and morphology were studied by scanning electron microscopy (SEM).

Preparation of Size Controlled Nanometric Spheres of Colloidal Silica for Synthetic Opal Manufacture

In this work, we present a modification of the sol-gel based, Stöber, Fink and Bohn’s (SBF) procedure for the preparation of nanometric spheres of silica with a monomodal distribution of size and controlled diameter. In the SBF method, tetraethyl orthosilicate (TEOS) is used as a precursor molecule and hydrolysis and condensation reactions to form chains and branches of Si-O bonds are carried out. The novelty of this work consists in the use of an aqueous ammonium hydroxide solution as ammonia source. Graphics of particle size as a function of reagent contents are presented (reaction yield control) and differences to the results from the original SBF method are discussed. This procedure is the very first step for the development of a sol-gel synthetic opals preparation process. As a result, the best route to prepare monodisperse spheres in the whole range of 250 to 850 nm is that of keeping constant the TEOS and NH3 contents at 0.28:1M varying water contents in the range of 8 – 12.5 M.

Pyrazolopyranopyrimidines as a Class of Anti-Inflammatory Agents

Pyrazolopyranopyrimidines 6a-c and 8a-c were prepared from the reaction of compounds 4a-c or 7a-c with methylamine or ammonium hydroxide solutions. Treatment of compounds 6a-c or 8a-c with 2-chloroethyl methyl ether afforded their corresponding acyclonucleosides 9a-c or 10a-c, respectively, as a new class of acyclonucleosides. All prepared compounds were tested as anti-inflammatory agents and some of them revealed moderate to potent anti-inflammatory activity.

Micro force sensor with piezoresistive amorphous carbon strain gauge

In this contribution we report for the first time on the successful integration of amorphous carbon (a-C) as a piezoresistive strain gauge into a silicon micro cantilever force sensor. Sputter-deposited a-C layers showing excellent tribological properties contain a percentage of nearly 20% of tetrahedral sp 3 carbon bonds as observed by optical absorption and Raman spectroscopy. Temperature-dependent transport measurements revealed hopping conduction between conducting sp 2 carbon sites embedded in the insulating skeletal matrix of sp 3 bonds. Changing their distance by strain a change of resistivity could be expected, which was investigated with layers sputter-deposited on a silicon membrane and structured by the lift-off technique using photo resist. Cantilevers comprising a-C strain gauges were etched out of this membrane using tetra methyl ammonium hydroxide (TMAH) and potassium hydroxide (KOH) solutions in a bulk silicon micromachining process. Realised prototypes were tested by applying a variable load to the cantilever free end. We found linear characteristics of the strain gauge resistance versus the applied force in the range of 0 to ±600 μN revealing piezoresistive gauge factors of a–C within 36–46.

The Sorption of Thorium and Americium onto Fresh and Degraded Ordinary Portland Cement and onto Green Tuff

ABSTRACTThe sorption of thorium and americium has been measured onto crushed samples of freshordinary Portland cement (OPC), degraded OPC (DOPC) and green tuff under a range of aqueous conditions as part of research into the disposal of TRU waste in Japan. Sorption onto OPC was measured from deionised water,3 mol dm−3sodium nitrate solution and simulated seawater, and onto DOPC from demineralised water; all solutions were pre-equilibrated with the relevant cement. Sorption onto tuff was measured from pre-equilibrated deionised water, 3 mol dm−3sodium nitrate solution, simulated seawater, OPC leachate and 1 mol dm−3ammonium hydroxide solution. RDvalues were determined from the amount of thorium or americium remaining in solution after centrifugation, 0.45 μm filtration and 10,000 nominal molecular weight cut-off (NMWCO) filtration. Centrifugation gave lower RDvalues than filtration. MeanRDvalues for sorption onto OPC and DOPC were in the range 4 × 104to ≥1 × 106cm3g−1for thorium, and 3 ×103to ≥1 × 105cm3g−1for americium, after filtration through 10,000 NMWCO filters. Mean RDvalues for thorium sorption onto tuff increased from2 × 103cm3g−1in tuff-equilibrated deionised water, to ≥ 4 × 106cm3g−1from ammonium hydroxide solution (10,000 NMWCO-filtration). A similar trend was seen for10,000 NMWCO-iltered americium samples where mean RDvalues increased from 4 × 103cm3g−1in deionised water to 1 × 105cm3g−1in ammonium hydroxide solution.

Preparation of a chemically amplified photosensitive polyimide based on norbornene‐end‐capped poly(amic acid ethoxymethylester)

AbstractA positive‐working chemically amplified photosensitive polyimide (PSPI) developable with basic aqueous solutions was obtained from poly(amic acid ethoxymethylester) (PAAE) as a polyimide precursor and diphenyliodonium 5‐hydroxynaphthalene‐1‐sulfonate (DINS) as a photoacid generator. The norbornene‐end‐capped PAAE based on 4,4′‐oxydiphthalic anhydride and 4,4′‐oxydianiline exhibited high transparency at 365 nm. The protection ratio of the ethoxymethyl groups was optimized to maximize the difference between the dissolution rates of the exposed and unexposed areas. The acid generated from DINS in the UV‐exposed region effectively deprotected the ethoxymethyl groups of PAAE by a chemical amplification mechanism. A 10‐μm‐thick film of the PSPI precursor system containing 16 wt % DINS exhibited a sensitivity (Do) of 1100 mJ cm−2 when developed with a 2.38 wt % aqueous tetramethyl ammonium hydroxide solution at room temperature. A fine, positive, 5‐μm line‐and‐space pattern was fabricated in a 15‐μm‐thick film with 1500 mJ cm−2 of UV exposure. This resolution is excellent in comparison with those previously reported for chemically amplified PSPIs, and such a film can thus be used as a buffer coating in semiconductor packaging. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5520–5528, 2005

Preparation and thermal decomposition of indium hydroxide

Indium hydroxides were prepared by the mixing of aqueous indium nitrate solution with sodium or ammonium hydroxide solutions under various conditions. The thermal decomposition of the resulting materials was examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectroscopy. It has been found that sodium hydroxide solution is more suitable than the addition of ammonium hydroxide solution to prepare indium hydroxide in well crystallization; the thermal decomposition of indium hydroxide, in which the composition is In(OH)3·xH2O where x£2, proceeds according to the following process: In(OH)3·xH2O®cubic In(OH)3®cubic In2O3

A co-precipitation technique to prepare BiNbO 4, MgTiO 3 and Mg 4Ta 2O 9 powders

A simple co-precipitation technique has been used successfully for the preparation of pure, ultrafine, single phase BiNbO 4 (BN), MgTiO 3 and Mg 4Ta 2O 9. An aqueous sodium hydroxide or ammonium hydroxide and ammonium carbonate solution was used to precipitate these cations as hydroxides and carbonates simultaneously under basic conditions. These precursors on heating at 750 °C, produce the respective powders. For comparison, these compounds were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM).

Preparation of tungsten oxide promoted zirconia by different methods

The platinum on tungsten oxide promoted zirconia preparation using different procedures has been studied. Zirconium oxyclhoride, ammonium hydroxide, ammonium metatungstate, and hexachloroplatinic acid solutions were used as raw materials in all cases. Tungsten oxide promoted zirconium hydroxide (obtained using the three first reagents) was calcined at 700 or 800 °C; then, each fraction was impregnated with hexachloroplatinic acid solutions. The solids were characterized by nitrogen adsorption, X-ray diffraction (XRD), NH 3–TPD, temperature-programmed reduction (TPR) and used as catalysts for n-hexane isomerization at 200 °C, WHSV = 4 h −1, 6 kg cm −2 and H 2: n-hexane (molar) = 7. The solids have different properties depending on the preparation procedure: surface area, pore size distribution, X-ray diffraction patterns, TPR profiles and activity for the isomerization reaction. Different WO x domain sizes are also obtained, which modify the TPR profiles and the catalytic activity for n-hexane isomerization.

An LC–MS–MS method for the determination of cyclizine in human serum

Cyclizine is a piperazine derivative with anti-emetic activity that is useful in the prevention and treatment of nausea and vomiting associated with motion sickness. A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is presented for the quantitation of cyclizine in serum. Sample pretreatment involved liquid-liquid extraction of 200 microl of serum with dichloromethane after the addition of 100 microl each of ammonium hydroxide and internal standard solutions. The extracts were analyzed by HPLC on a Luna C18 reversed-phase column and an ion-trap mass spectrometer with an electrospray interface. A limit of detection of 1 ng/ml was determined which allowed for the reliable measurement of cyclizine in the serum of human subjects. The method was found to be linear over the calibration range of 2.5-100 ng/ml. The applicability of this method was demonstrated by the analysis of serum obtained from a human volunteer following administration of a single 50 mg cyclizine hydrochloride tablet. The reported method was observed to have the necessary sensitivity, selectivity, precision and accuracy for monitoring cyclizine concentrations in human subjects following oral administration.

Properties of CdS thin films grown by CBD as a function of thiourea concentration

Abstract This paper reports a study of the growth rate and optical properties of CdS thin films prepared by the chemical bath deposition technique. For the deposition an aqueous solution of cadmium chloride, ammonium chloride, ammonium hydroxide and thiourea were used, the films were deposited on conducting glass (SnO2: F). The growth kinetics is relatively fast when the quantity of thiourea is increased in the deposition solution and higher value of band gap is obtained ( E g = 2.44 eV ). The films show good transmittance in the visible region.

Contribution of ammonium to stimulation of smooth pigweed (Amaranthus hybridus L.) germination by extracts of hairy vetch (Vicia villosa Roth) residue

Hairy vetch is a leguminous winter annual cover crop that provides a significant contribution toward meeting the nitrogen requirement of succeeding crops. Hairy vetch residue is capable of suppressing weeds, but low levels of residue can intermittently stimulate the emergence of weeds, particularly smooth pigweed. This research was conducted to assess the inhibitory and stimulatory effects of hairy vetch extracts on two smooth pigweed lots with differing dormancy conditions under differing germination conditions (25 or 35°C in light or dark). Full‐strength extracts inhibited germination of both lots under all conditions, a result explained by the inhibitory osmotic potential of the full‐strength extract. At ≤ 0.1× proportions of the hairy vetch extract, there was a slight stimulation of germination above that of the control (average = 11%) of both lots of pigweed under all germination conditions, except for a large stimulation (87%) by the more dormant lot at 25°C in light. A similar response to ammonium hydroxide solutions was observed, in which germination stimulation averaged 7% for all conditions except for germination of the dormant pigweed lot that was stimulated 115% by 15 p.p.m. of ammonium ( ) at 25°C in light. As the concentration in the hairy vetch extract was similar to that in the ammonium hydroxide solutions that promoted the largest stimulation of germination, and because there was a high correlation between the degree of germination stimulation by hairy vetch extracts and by ammonium hydroxide, appears to be the principle ingredient in the extract responsible for stimulation of smooth pigweed germination.