Ammonium Hydroxide Solution Research Articles

Hydrothermal growth and characterization of ZnO thin film on sapphire (0001) substrate with p-GaN buffer layer

Monocrystalline ZnO thin films on p-GaN/sapphire (0001) substrate were grown by single step hydrothermal technique at 90 °C. ZnO thin films were grown in aqueous solution of zinc nitrate and ammonium hydroxide. The X-ray diffraction, scanning electron microscopy and room temperature photoluminescence analysis were carried out to characterize structural, morphological and optical properties of the films. The thin films revealed single crystalline nature and wurtzite symmetry. The films were c-axis oriented and have honeycomb like pitted surface morphology. The epitaxial relationship between ZnO film and p-GaN buffer layer was observed to be (0001)[112¯0] ZnO||(0001)[112¯0] GaN. Sharp luminescent peak centered at 376 nm due excitonic emission and broad deep level emission peak were obtained from room temperature photoluminescence measurement of the ZnO thin film.

Surface characterisation of daguerreotypes with the optical metrological technique of confocal microscopy

This paper presents non-perturbing techniques of optical and surface metrology applied to surface studies of daguerreotypes. Daguerreotypes are positive images developed directly on the surface of silvered copper plates. The image is a submicrometre, ultra fine structured surface that exceeds the resolving power of the optical microscope for surface examination. Confocal white light microscopy is shown to be a useful technique for examining the three-dimensional ultra fine structure of the daguerreotype image. This technique provides quantitative information of surface characteristics using established surface roughness parameters to document the daguerreotype surface. Examination at this level can measure changes due to environmentally induced deterioration and provide comparative data of before and after chemical and physical treatment. Confocal microscopy shows considerable potential in the evaluation and documentation of both daguerreotype condition and treatments performed on the image structure. Confocal microscopy was used in the close examination of the Southworth and Hawes portrait of an unidentified man and it demonstrated the ability to unambiguously identify and quantify surface damage. The daguerreotype of an unidentified woman wearing a bonnet was treated with ammonium hydroxide solution to remove tarnish and surface changes were followed with confocal microscopy.

Effects of aging on beef chuck and loin muscles enhanced with ammonium hydroxide and salt1,2

The objective of this study was to determine whether aging would alter the beneficial effects (tenderness, juiciness, and flavor) of enhancing beef chuck and round steaks with a 20% solution of water, ammonium hydroxide, salt, and carbon monoxide. A randomized, complete block design was used, with 2 treatments [0% (control) and 20% (pump)], 3 aging periods (1, 2, and 3 wk), 3 muscles (M. triceps brachii from the clod heart, M. biceps femoris from the sirloin cap, and M. rectus femoris from the knuckle), and 3 replications. There were a total of 12 subprimals per treatment per aging period (n = 72 each). Individual steaks were cut to a thickness of 2.54 cm and packaged in a high-oxygen modified-atmosphere package (80% oxygen, 20% carbon dioxide). At the end of the aging period, steaks were vacuum packaged and frozen. Steaks were used to determine Warner-Bratzler shear force (WBS) and consumer sensory ratings. For all muscles, WBS values were lower for pump steaks than control at every aging period (P < 0.050). In addition, as aging period increased, WBS values for all steaks increased. Consumer taste panels revealed more desirability for tenderness, juiciness, flavor, and overall acceptability for pump steaks than control steaks. In addition, steaks aged for 1 d were more desirable than steaks aged for 7 and 14 d (P < 0.050). These data indicate that aging does not decrease the benefits (tenderness, juiciness, and flavor) of enhancement.

Enhancement of beef chuck and loin muscles with ammonium hydroxide and salt1,2

The objective of this study was to evaluate the tenderness of beef chuck and round muscles when enhanced with ammonium hydroxide and salt at different pump levels. A randomized, complete block design of 4 treatments and 3 muscles with 3 replications was used, with a total of 15 subprimals per treatment. Treatments included a 0% (CON), 15% (T15), 22.5% (T22), and 30% (T30) target pump. The triceps brachii (TB), biceps femoris (BF), and rectus femoris (RF) muscles were studied. Muscles were injected with a solution of ammonium hydroxide and sodium chloride (patent-pending technology from Freezing Machines Inc., Dakota Dunes, SD). Individual steaks were cut to a thickness of 2.54 cm, vacuum-packaged in trays, and frozen. Warner-Bratzler shear force, pH, and sensory evaluations were determined. Shear force decreased as the target pump percentage increased for all muscles (P < 0.050): TB = 39.9, 35.1, 32.1, and 27.0 N; BF = 39.4, 26.2, 23.3, and 19.3 N; RF = 42.7, 32.9, 30.7, and 28.9 N for CON, T15, T22, and T30, respectively. In all cases, there were no shear force differences between T15 and T22 (P > 0.050). As percentage pump increased, pH increased. The ultimate pH was moderately strongly to strongly related to shear force (r = 0.55, 0.70, and 0.80 for RF, TB, and BF, respectively). Trained taste panel ratings revealed an increase in tenderness, decrease in connective tissue, and an increase in juiciness as pump level increased for all muscles. In all cases but one (juiciness of the RF), the CON had the least desirable ratings and shear force values (P < 0.050). There were no major differences between T15 and T22, and T30 steaks tended to have an uncharacteristic soft and mushy texture. For this reason a 20% target pump level was determined to be the optimum pump level. These data suggest that adjusting pH in beef with ammonium hydroxide and salt can increase tenderness in muscles from the beef chuck and round. Any level of treatment was beneficial, with the greatest shear force benefit occurring in muscle pumped to 30%.

Facile and Efficient One‐Pot Protocol for Synthesis of 5‐Phenyl‐1,4‐benzodiazepine‐2‐one Derivatives

Several new derivatives of 5‐pheny‐1,4‐benzodiazepine‐2‐ones were synthesized from 2‐aminobenzophenone derivatives containing electron‐withdrawing substituents in one pot with mild conditions using THF as a solvent with ammonium hydroxide solution and K2CO3.

Growth of ZnO thin film on p-GaN/sapphire (0 0 0 1) by simple hydrothermal technique

Zinc oxide (ZnO) heteroepitaxial thin films were successfully grown on p-GaN/sapphire (0 0 0 1) by single-step hydrothermal route at a low temperature of 90 °C. Continuous ZnO thin films with c-axis orientation were grown in aqueous solution of zinc acetate di-hydrate and ammonium hydroxide. X-ray diffraction, scanning electron microscopy and room temperature photoluminescence were carried out for structural, morphological and optical property analysis. The as-grown ZnO films showed preferential growth along (0 0 0 1) direction. The in-plane orientation between ZnO thin film and p-GaN buffer layer was found to be [1 1 2¯ 0] ZnO∥[1 1 2¯ 0] GaN. Sharp luminescence peak centered at 377 nm due to excitonic recombination from ZnO thin film was observed.

Preparation and characterization of nanostructured Ni(OH) 2 and NiO thin films by a simple solution growth process

Nanostructured Ni(OH) 2 thin films were prepared by a simple solution growth process with F − and NH 3 used as Ni 2+ coordination agents, and ammonia hydroxide solution used as OH − supplier to accelerate the hydrolyzation of nickel complex species. The results showed Ni(OH) 2 thin films were constructed mainly with hexagonal β - Ni ( OH ) 2 nanorods; the F − and NH 3 in reactive solutions played important roles in the film growth process; and solution pH had great influence on the morphologies of thin films, which was explained by the competition of Ni(OH) 2 nucleation and growth in solutions. NiO crystallinity thin films were obtained by annealing Ni(OH) 2 thin films at 400 °C for 2 h and the morphologies of the Ni(OH) 2 thin films were sustained well during the annealed process.

Study of rounded concave and sharp edge convex corners undercutting in CMOS compatible anisotropic etchants

In this paper, we have studied the undercutting at rounded concave and sharp convex corners in (1 0 0)-silicon wafers using a complementary metal-oxide semiconductor (CMOS) compatible tetramethyl ammonium hydroxide (TMAH) solution with and without surfactant. In order to minimize the undercutting at both corner types while keeping reasonable etch rates, smooth etched-surfaces and CMOS compatibility, the non-ionic surfactant NC-200 that contains 100% polyoxyethylene-alkyl-phenyl-ether is considered. The effect of concentration and etching temperature is studied using 10, 20 and 25 wt% TMAH solutions at 60, 70 and 80 °C. When NC-200 at 0.1% of the total volume of the etchant is used, the undercutting ratio at both rounded concave and sharp convex corners is beneficially reduced as the etchant concentration is increased while, simultaneously, the etch rate increases. This is the opposite trend to the etch characteristics of pure TMAH. In addition, the rough etched surface morphology at low concentration is also improved by using NC-200.

Leaching Kinetics of Tungstic Acid and in situ Synthesis of Tungsten Carbide in Silica Gel Matrix

Leaching of tungstic acid is carried out in ammonium hydroxide solution at two different pH (8 and 10.5), at three different temperatures of 40°, 50° and 60°C. It Is observed that initially the dissolution rate is very fast followed by decrease in rate with time. It also increases with increase of temperature and pH. The mechanism of isothermal leaching kinetics of tungstic acid in ammonium hydroxide is mainly of contracting geometry type. Ammonium tungstate has been used as a precursor to synthesize nano tungsten carbide in the silica gel matrix by in situ generation of hydrogen and extremely fine carbon. The size of tungsten carbide is found to be in the nm range.

Free-standing SiO2 films containing Si nanocrystals directly suitable for transmission electron microscopy

Free-standing SiOx films were prepared by molecular beam deposition following back side Silicon (Si) wafer etching in tetramethyl ammonium hydroxide (TMAH) solution. Transmission Electron Microscopy confirms the presence of Si nanocrystals in the as-prepared film. Raman spectroscopy show that deep structural film reorganization appears during high temperature laser treatment. The laser annealing decreases photoluminescence from the films.

Investigation of dye-doped sol–gels for ammonia gas sensing

Sol–gel films doped with fluorescein (FL) and phenol red (PR) dyes were evaluated for their responses to ammonia gas. In a steady state, the sensors respond to the gas-phase ammonia evolved from ammonium hydroxide solutions in the range of 5 × 10 −6 to 0.05 M for FL-doped gels, and 10 −4 to 1 M for PR-doped gels. The sensors have high selectivity for ammonia against larger amines and moderate selectivity against methyl and ethylamines. The FL-gel exhibits rapid and reproducible response to dry NH 3 gas samples of 9–50 ppm, while PR-gel is insensitive to ammonia in this low concentration range. The life-times of the sensors are over a year.

Synthesis and characterization of polymeric resins with aliphatic and aromatic amino ligands and their sorption behavior towards gold from ammonium hydroxide solutions

The functional resins with amino ligands are synthesized by the modification of lightly crosslinked poly(vinylbenzyl chloride–divinylbenzene) matrix with the following amines: 1-methylpiperazine, ethylenediamine, dipropylamine, 1-methylimidazole, 2-mercapto-1-methylimidazole, 1,2-dimethylimidazole and 1-(3-aminopropyl) imidazole. Two methods of the modification reactions were employed, the first one is the traditional heating of the polymer with either neat amine or amine solution in an appropriate solvent, the second method is heating of the reaction mixture in a microwave reactor. The resultant resins show different degrees of modification depending on the applied method and contain 1.61–3.68 mmol of ligand/g. The 1-methylimidazole resin displays the highest affinity towards gold from ammonium buffer (100 g/dm 3 NH 3 · H 2O, 50 g/dm 3 (NH 4) 2SO 4). For this resin, the sorption is as high as 15.5 mg/g and log K d (distribution coefficient) value is 2.94. All resins are highly selective and they do not sorb copper amino complexes. These polymeric materials were characterized using nitrogen, sulfur and chlorine elemental analysis and FTIR spectroscopy.

Effect of Ca/P Ratio on the Dissolution of Calcium Phosphate Powders

Calcium phosphate ceramics (CPC) have been attractively used in different areas of biomedical applications, such as substances of artificial hard tissue replacement implants, drug delivery system due to their biocompatibility and bioactivity. In this work, three calcium phosphate powders between Ca/P molar ratio 1.50-1.67 were synthesized by aqueous precipitation method, using the mixture of Ca(NO3)2·4H2O and H3PO4 solutions to ammonia solution. During the precipitation reaction, Ca/P molar ratio was adjusted by controlling pH of the solution between 8.0 and 10.5 by the addition of ammonium hydroxide solution. All powders were treated at 800 oC for 2 hrs. The calcined powders were immersed in pH 7.4 distilled water at 37°C for 3 and 7 days. Decomposition and related dissolution with the various Ca/P ratios were investigated by XRD, FTIR, and TEM observation.

Distinct Uptake Mechanisms but Similar Intracellular Processing of Two Different Toll-like Receptor Ligand-Peptide Conjugates in Dendritic Cells

Covalent conjugation of Toll-like receptor ligands (TLR-L) to synthetic antigenic peptides strongly improves antigen presentation in vitro and T lymphocyte priming in vivo. These molecularly well defined TLR-L-peptide conjugates, constitute an attractive vaccination modality, sharing the peptide antigen and a defined adjuvant in one single molecule. We have analyzed the intracellular trafficking and processing of two TLR-L conjugates in dendritic cells (DCs). Long synthetic peptides containing an ovalbumin cytotoxic T-cell epitope were chemically conjugated to two different TLR-Ls the TLR2 ligand, Pam(3)CysSK(4) (Pam) or the TLR9 ligand CpG. Rapid and enhanced uptake of both types of TLR-L-conjugated peptide occurred in DCs. Moreover, TLR-L conjugation greatly enhanced antigen presentation, a process that was dependent on endosomal acidification, proteasomal cleavage, and TAP translocation. The uptake of the CpG approximately conjugate was independent of endosomally-expressed TLR9 as reported previously. Unexpectedly, we found that Pam approximately conjugated peptides were likewise internalized independently of the expression of cell surface-expressed TLR2. Further characterization of the uptake mechanisms revealed that TLR2-L employed a different uptake route than TLR9-L. Inhibition of clathrin- or caveolin-dependent endocytosis greatly reduced uptake and antigen presentation of the Pam-conjugate. In contrast, internalization and antigen presentation of CpG approximately conjugates was independent of clathrin-coated pits but partly dependent on caveolae formation. Importantly, in contrast to the TLR-independent uptake of the conjugates, TLR expression and downstream TLR signaling was required for dendritic cell maturation and for priming of naïve CD8(+) T-cells. Together, our data show that targeting to two distinct TLRs requires distinct uptake mechanism but follows similar trafficking and intracellular processing pathways leading to optimal antigen presentation and T-cell priming.

Comparison of liquid chromatographic methods with direct detection for the analysis of gentamicin

Several liquid chromatographic (LC) methods have been described for the analysis of gentamicin. LC combined with pulsed electrochemical detection (LC-PED) or evaporative light scattering detection (LC-ELSD) was found to be the most suitable technique. A first method, previously developed by Adams et al. used a poly(styrene-divinyl benzene) stationary phase with a mobile phase containing sodium sulphate, sodium-1-octanesulphonate, tetrahydrofuran, 0.2 M phosphate buffer (pH 3) and water. However, the polymer columns show low efficiency, which also leads to poor sensitivity. So, recently the use of newer conventional C18 columns was further investigated. Improved separation was obtained using a Supelcosil LC-18-DB column with an adapted mobile phase. Another method derived from a company method was checked by using a Gemini column and a mobile phase containing an aqueous solution of trifluoroacetic acid (TFA) and pentafluoropropionic acid (PFPA) adjusted to pH 2.6 with sodium hydroxide (NaOH). This method was transferred to ELSD by replacing the non-volatile NaOH with volatile ammonium hydroxide solution. A volatile method, which was originally developed for ELSD using an aqueous solution of 50 mM TFA and gradient elution with methanol, was also combined with PED. In this study, these methods were compared with regard to their selectivity, sensitivity and ease of use.

A co-precipitation technique to prepare BiTaO4 powders

A simple co-precipitation technique has been successfully used for the preparation of pure ultrafine single phase BiTaO4. A standard ammonium hydroxide solution was used to precipitate Bi3+ and Ta5+ cations as hydroxides simultaneously under basic conditions. This precursor, on heating at 600 °C, produced product phase. This is the lowest temperature for the formation of BiTaO4 phase so far reported in the literature. For comparison BiTaO4 powders were also prepared by the traditional solid state method. The phase contents and lattice parameters were studied by the powder X-ray diffraction (XRD).

Nanocontact Printing Using a Hydrogen Silsesquioxane Stamp with Low E-beam Dose

Hydrogen silsesquioxane (HSQ) soft stamps with hard upper-part protruding areas are proposed for nanocontact printing in this study. The stamps are fabricated by low-dose E-beam lithography on low-temperature prebaked HSQ films with development in low-concentration tetramethyl ammonium hydroxide (TMAH) solution. In order to obtain an optimum nanoscale stamp, E-beam dose, TMAH concentration, and development time were set as fabrication parameters. Scanning electron microscopy (SEM) images of the HSQ stamps exhibited nanopatterns that have a superior sidewall profile: lines with an aspect ratio of 6.86. New material systems are suggested in our nanocontact printing. Poly-l-lysine and aminosilane were separately used as inks for the HSQ stamps on a HSQ/Si substrate at room temperature. Ink thickness, pressing pressure, and pressing time were manipulated to find the optimum condition for the printing, and afterwards the transferred patterns were examined by the utilization of fluorescence microscope, atomic force microscopy, and SEM. Experimental results demonstrated that line patterns with about in length of both inks are properly transferred onto the HSQ/Si substrate, and the HSQ stamps were also verified to possess good durability and repeatability.

A co-precipitation technique to prepare BiNbO 4 powders

A simple co-precipitation technique was successfully used for the preparation of pure ultrafine single phase BiNbO 4. A standard ammonium hydroxide solution was used to precipitate Bi 3+ and Ta 5+ cations as hydroxides simultaneously under basic conditions. For comparison, BN powders were also prepared by the traditional solid-state method. It is observed that the co-precipitation technique produces BiNbO 4 on heating at 600 °C, whereas complete phase formation occurs only at 800 °C in the solid-state method. The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD).

Molecularly imprinted sol–gel nanoparticles for mass-sensitive engine oil degradation sensing

Titanate sol-gel layers imprinted with midchain carbonic acids have proven highly useful for detecting engine oil degradation processes owing to selective incorporation of oxidised base oil components. Synthesising the material from TiCl(4) in CCl(4) and precipitating with water leads to imprinted TiO(2) nanoparticles with a diameter of 200-300 nm. Replacing the water by a 1 M ammonium hydroxide solution reduces the average particle size to 50-100 nm with retention of the interaction capabilities. Experiments with the latter solution revealed that the 100-nm particles take up substantially more analyte, indicating a size-dependent phenomenon. As the number of interaction sites within each material is the same, this cannot be a consequence of thermodynamics but must be one of accessibility. The sensor characteristic of water-precipitated particles towards engine oil degradation products shows substantially increased sensitivity and dynamic range compared with the corresponding thin films. Coating quartz crystal microbalances with such nanoparticle materials leads to engine oil degradation sensors owing to incorporation of acidic base oil oxidation products. Interaction studies over a large range of layer thicknesses revealed that both the absolute signal and the steepness of the correlation between the sensor signal and the layer height is 2 times higher for the particles.

A co-precipitation method for preparation of Bi 3TiNbO 9 powders

A simple co-precipitation technique has been successfully used for the preparation of pure, ultrafine, single phase Bi 3TiNbO 9 (BTN). An aqueous ammonium hydroxide solution was used to simultaneously precipitate Bi 3+, Ti 4+ and Nb 5+ cations as hydroxides under basic conditions (pH ∼9). No pyrochlore phase was found while heating powder at 500 °C and pure BTN phase was found to be formed by X-ray diffraction (XRD). For comparison, BTN samples were also synthesized by the traditional solid state method. The sequence of phase formation in both cases were investigated by XRD studies.