Ammonium Bicarbonate Solution Research Articles

Synthesis and Characterization of Different γ-Al2O3 Nanocatalysts for Methanol Dehydration to Dimethyl Ether

Abstract A simple co-precipitation method was utilized to synthesize γ-Al2O3 catalysts using aluminum nitrate nonahydrate as the source of aluminum cations for methanol dehydration to dimethyl ether (DME). Different precipitating agents comprising ammonium carbonate, ammonium bicarbonate and ammonia solutions were used for preparation of the samples. The catalysts were characterized by XRD, FTIR, SEM, NH3-TPD and N2 adsorption-desorption techniques. The sample prepared by ammonia solution had the highest acidity among the synthesized catalysts. Also, N2 adsorption-desorption results showed suitable textural properties for all of the synthesized samples. Vapor phase dehydration of methanol to DME was performed in the fixed bed micro reactor over the synthesized catalysts and commercial one for comparison purposes. The effects of different characteristics of catalysts such as surface area, acidity, sintering factor and temperature as an operating parameter on performance of catalysts were investigated. The catalyst prepared by ammonia solution showed best catalytic activity due to the suitable textural properties and high amount of acidic sites. Also, the results showed that only high acid strength can’t result high yield of DME for a solid acid catalyst.

Influence of concentration polarization on flux behavior in forward osmosis during desalination using ammonium bicarbonate

Forward osmosis is recognized as one of the promising membrane based desalination process and viable alternative to reverse osmosis as a lower cost and more environmentally friendly desalination technology. The solution of ammonium bicarbonate was used as a draw solution to extract water from a feed containing 0.5M sodium chloride. The water was transported from feed to draw solution and it can be recovered upon moderate heating of the draw solution, which is decomposed into ammonia and carbon dioxide gases producing pure water. The mechanism of water transport in the case of feed containing pure water or sodium chloride has been elucidated depending upon the orientation of the membrane. The concentrative and dilutive internal concentration polarizations played a major role in a situation when feed was towards support layer and feed was towards active layer, respectively. For the desalination applications, the feed towards support layer was found to be best mode to achieve higher flux. An increase in draw solution concentration from 1.0 to 3.6M, resulted in an increase in flux values from 0.58 to 1.39×10−6m3m−2s−1 at 30°C. Further, an increase in temperature of the draw solution from 30 to 45°C resulted in increase in transmembrane flux from 1.39 to 2.11×10−6m3m−2s−1 at the highest draw solution concentration. It was concluded that forward osmosis can prove to be a feasible technique for the recovery of water from saline water.

Electrothermal Supercharging of Proteins in Native Electrospray Ionization

The formation of high charge-state protein ions with nanoelectrospray ionization (nESI) from purely aqueous ammonium bicarbonate solutions at neutral pH, where the proteins have native or native-like conformations prior to ESI droplet formation, is demonstrated. This "electrothermal" supercharging method depends on the temperature of the instrument entrance capillary, the nESI spray potential, and the solution ionic strength and buffer, although other factors almost certainly contribute. Mass spectra obtained with electrothermal supercharging appear similar to those obtained from denaturing solutions where charging beyond the total number of basic sites can be achieved. For example, a 17+ ion of bovine ubiquitin was formed by nESI of a 100 mM ammonium bicarbonate, pH 7.0, solution, which is three more charges than the total number of basic amino acids plus the N-terminus. Heating of the ESI droplets in the vacuum/atmosphere interface and the concomitant denaturation of the protein in the ESI droplets prior to ion formation appears to be the primary origin of the very high charge-state ions formed from these purely aqueous, buffered solutions. nESI mass spectra resembling those obtained under traditional native or denaturing conditions can be reversibly obtained simply by toggling the spray voltage between low and high values.

Power generation by coupling reverse electrodialysis and ammonium bicarbonate: Implication for recovery of waste heat

Utilization of waste heat has attracted increasing attentions due to energy crisis and environmental problems. Efficiency of traditional thermodynamic cycles for waste heat conversion is limited by the temperature of heat sources. We propose here the concept of a novel waste heat conversion system, namely a thermal-driven electrochemical generator (TDEG), which comprises a reverse electrodialysis (RED) stack and a distillation column. By using thermally instable ammonium bicarbonate solutions as working fluids, waste heat can be converted to electricity. The feasibility of NH4HCO3 to generate electricity for TDEG was validated in a RED stack for the first time. Two important operating conditions influencing power output of RED stack, i.e. concentration of low concentration solution and flow rate of feed solutions were optimized to be 0.02M and 800mL/min, respectively. A maximum power density of 0.33W/m2 was obtained for the specific RED stack. Ionic flux efficiency and energy efficiency under the optimal condition were 88% and 31%, respectively. The study lays a foundation for the establishment of the promising TDEG.

Experimental Studies on the Influence of HCO<sub>3</sub>- on Absorption and Desorption of CO<sub>2</sub> from Ammonia Solution

With aqueous ammonia in the process of CO2 absorption and desorption to join sodium bicarbonate, the influence of HCO3- on CO2 absorption and desorption from ammonia solution was investigated through the experimental analysis of the desorption quantity of CO2, desorption rate, CO2 loading and the absorption rate. The experimental results showed that, in experimental conditions, The desorption rate decreased gradually with increasing ammonia concentrations. The desorption rate increased 12%, 17%, 19% and 28.8% when 1 mol/L of ammonia solution is added in 0.1 mol/L, 0.3 mol/L, 0.5 mol/L and 1 mol/L of sodium bicarbonate. The higher concentration of ammonium bicarbonate solution which was added sodium bicarbonate，the more observably the effect of CO2 desorption was promoted. The absorption rate had dropped when absorption process added 0.3 mol/L sodium bicarbonate, the CO2 loading was a little change.

Preparation of ZnO Nanostructures by Chemical Precipitation Method

ZnO nanostructures have been successfully prepared by dissolution–reprecipitation of micro-sized ZnO powder from aqueous ammonium hydrogencarbonate solution in the presence of thiourea, followed by calcination at 400°C for 1 h. The products were characterized by simultaneous thermal analysis, x-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, and Fourier-transform infrared spectroscopy analysis. The results reveal that the morphology and particle size of the as-prepared ZnO samples are susceptible to the amount of added thiourea. The developed method has potential for application in industry due to simple processing and inexpensive reagents.

Preparation and Characterization of NiO Nanoparticles by Chemical Precipitation Method

NiO nanoparticles have been successfully prepared by dissolution-reprecipitation of micro-sized NiO powder from aqueous ammonium hydrogencarbonate solution in the presence of urea followed by calcination at 400°C for 1 h. The products were characterized by simultaneous thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourrier transform infrared spectroscopy (FT-IR). The results show that the as-prepared NiO samples have cubic crystallite structure with the average particle size ranging from 19 nm to 40 nm calculated by the Scherrer formula. The developed method has potential for application in industry due to simplicity and inexpensive materials.

Simultaneous determination of six alkaloids in Coptis chinensis of different regions by RP-HPLC

A reversed-phase HPLC method for simultaneous determination of gatrorrhizine, columbamine, epiberberine, coptisine, palmatine and berberine in Coptis chinensis was developed. Analysis was carried out on an Xtimate C18 column (4.6 mm x 250 mm, 5 microm) eluted with acetonitrile-30 mmol x L(-1) ammonium bicarbonate solution (including 0.7% ammonia and 0.1% triethylamine) by gradient elution. The detective wavelength was 270 nm, the column temperature was 30 degrees C, and the flow rate was 1.0 mL x min(-1). By the above method, the linear ranges of gatrorrhizine, columbamine, epiberberine, coptisine, palmatine and berberine were 0.85-16.96 (r = 0.9997), 1.25-24.96 (r = 0.999 5), 2.05-40.96 (r = 0.999 9), 3.65-72.96 (r = 0.999 9), 2.88-57.60 (r = 0. 999 8),13.25-264.96 mg x L(-1) (r = 0.999 6), respectively. The average recoveries (n = 6) of the six alkaloids were 101.6% (RSD 1.3%),102.5% (RSD 1.5%), 100.8% (RSD 1.9%),102. 6% (RSD 1.2%), 97.80% (RSD 1.3%), 99.01% (RSD 1.5%), respectively. The determined results demonstrate that there is a significant difference in the contents of six alkaloids and total alkaloids among the tested samples. The method is accurate, reliable and repeatable for simultaneous determination of gatrorrhizine, columbamine, epiberberine, coptisine, palmatine and berberine in C. chinensis.

Study on co-precipitation synthesized Y 3Al 5O 12:Ce yellow phosphor for white LED

A precursor of the Y 3Al 5O 12:Ce (YAG:Ce) phosphor was obtained by co-precipitation of the solution of high purity nitrates with ammonium bicarbonate solution. The precipitation process of the precursor was studied in this work. YAG:Ce yellow phosphors with fine morphology was synthesized by annealing the precursor at a reducing atmosphere. The crystal phase, microstructure of the phosphors and their photoluminescence were investigated. The results indicated that the pure phase of YAG:Ce could be obtained at 1673 K annealing temperature. The particles of phosphor were basically spherical in shape with the mean size less than 2 μm. The excitation spectrum showed a broad and strong absorption band at about 460 nm, compatible with the excited wavelength of commercial blue light emitting diode (LED) for white LED lighting. Bright yellow-emission located at 540 nm was observed.

Experimental approaches to feed solution permeability in pressure-driven membrane separation processes

This study demonstrates the application of the solution-diffusion pore-flow fluid-resistance (SDPFFR) model, which is used to describe solvent transfer in pressure-driven membrane separation processes. The experimental work is carried out in a reverse osmosis (RO) setup by using two different membranes, TFC-HR and TFC-ULP, manufactured by Koch Membranes Systems, Inc. (USA). Characterization for these membranes by using the transmission electron microscopy (TEM) is also presented. Aqueous solutions of sodium chloride and ammonium bicarbonate were used as feed at 15, 25, and 35 °C. The results show that water transfer in the feed side of the membrane is controlled by the molecular properties of the solute in addition to the operational conditions. Water permeability in the feed solution has been observed to increase as the solute hydration strength or concentration decrease, and as the temperature and the hydraulic pressure increase. The validated model explains the interaction between water permeability in the feed solution and water permeability inside the membrane material. The model shows good agreement with the experimental results. It provides good description for solvent transfer in membrane separation processes and may be useful for future development and design applications, when based on experimental data.

Identification and Characterization of a Novel Nuclear Protein Complex Involved in Nuclear Hormone Receptor-mediated Gene Regulation

NRC/NCoA6 plays an important role in mediating the effects of ligand-bound nuclear hormone receptors as well as other transcription factors. NRC interacting factor 1 (NIF-1) was cloned as a novel factor that interacts in vivo with NRC. Although NIF-1 does not directly interact with nuclear hormone receptors, it enhances activation by nuclear hormone receptors presumably through its interaction with NRC. To further understand the cellular and biological function of NIF-1, we identified NIF-1-associated proteins by in-solution proteolysis followed by mass spectrometry. The identified components revealed factors involved in histone methylation and cell cycle control and include Ash2L, RbBP5, WDR5, HCF-1, DBC-1, and EMSY. Although the NIF-1 complex contains Ash2L, RbBP5, and WDR5, suggesting that the complex might methylate histone H3-Lys-4, we found that the complex contains a H3 methyltransferase activity that modifies a residue other than H3-Lys-4. The identified components form at least two distinctly sized NIF-1 complexes. DBC-1 and EMSY were identified as integral components of an NIF-1 complex of approximately 1.5 MDa and were found to play an important role in the regulation of nuclear receptor-mediated transcription. Stimulation of the Sox9 and HoxA1 genes by retinoic acid receptor-alpha was found to require both DBC-1 and EMSY in addition to NIF-1 for maximal transcriptional activation. Interestingly, NRC was not identified as a component of the NIF-1 complex, suggesting that NIF-1 and NRC do not exist as stable in vitro purified complexes, although the separate NIF-1 and NRC complexes appear to functionally interact in the cell.

Determination of arsenic species and arsenosugars in marine samples by HPLC‐ICP‐MS

AbstractArsenic speciation analysis in marine samples was performed using high‐pressure liquid chromatography (HPLC) with ICP‐MS detection. The separation of eight arsenic species, viz. AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+, was achieved on a Shiseido Capcell Pak C18 column using an isocratic eluent (pH 3.0), in which conditions AsIII and MMA were co‐eluted. The method was successfully applied to several marine samples, e.g. oyster, fish, shrimp and marine algae. For the extraction of arsenic from seafood products, low‐power microwave digestion was employed, and for the extraction of arsenic from marine algae, sonicated extraction was employed. The separation of arsenosugars in the extracts from marine algae was achieved on an anion exchange column, Hamilton PRP X‐100, using ammonium hydrogen carbonate solution (pH 8.4). The concentrations of arsenosugar‐2, ‐3 and ‐4 in the extracts from the marine algae were analyzed to test the use of a Fucus sample as a reference standard material and were in the range 3.6–27.5 µg g−1, which accounted for 6.0–34.9% of total arsenic. Copyright © 2007 John Wiley & Sons, Ltd.

Analysis and Quantification of Diagnostic Serum Markers and Protein Signatures for Gaucher Disease

Novel approaches for the qualitative and quantitative proteomics analysis by nanoscale LC-MS applied to the study of protein expression response in depleted and undepleted serum of Gaucher patients undergoing enzyme replacement therapy are presented. Particular emphasis is given to the method reproducibility of these LC-MS experiments without the use of isotopic labels. The level of chitotriosidase, an established Gaucher biomarker, was assessed by means of an absolute concentration determination technique for alternate scanning LC-MS generated data. Disease associated proteins, including fibrinogens, complement cascade proteins, and members of the high density lipoprotein serum content, were recognized by various clustering methods and sorting and intensity profile grouping of identified peptides. Condition-unique LC-MS protein signatures could be generated utilizing the measured serum protein concentrations and are presented for all investigated conditions. The clustering results of the study were also used as input for gene ontology searches to determine the correlation between the molecular functions of the identified peptides and proteins.

A New Homogeneous Precipitation Route to Ammonium Aluminum Carbonate Hydroxide

A new precipitation route to ammonium aluminum carbonate hydroxide (AACH) was presented. There was an incubation period before AACH precipitated. Effects of synthesis parameters such as pH of ammonium hydrogen carbonate solution, precipitation temperature, concentration of aluminum citrate and type of anions on the precipitation of ammonium aluminum carbonate hydroxide were discussed. It was found that the incubation period decreased with the increasing pH of AHC solution, concentration of aluminum citrate and the decreasing reaction temperature. Compared to NO3 -, SO4 2- delayed the formation of AACH and enlarged the particle size of AACH.

Unusual N-Glycan Structures in α-Mannosidase II/IIx Double Null Embryos Identified by a Systematic Glycomics Approach Based on Two-dimensional LC Mapping and Matrix-dependent Selective Fragmentation Method in MALDI-TOF/TOF Mass Spectrometry

alpha-Mannosidase IIx (MX) is an enzyme closely related to alpha-mannosidase II (MII), a key enzyme in N-glycan biosynthesis that catalyzes the first step in conversion of hybrid- to complex-type N-glycans in Golgi apparatus. Recently we generated MII/MX double knock-out mice and found that double nulls completely lack the complex-type N-glycans (Akama, T. O., Nakagawa, H., Wong, N. K., Sutton-Smith, M., Dell, A., Morris, H. R., Nakayama, J., Nishimura, S.-I., Pai, A., Moremen, K. W., Marth, J. D., and Fukuda, M. N. (2006) Essential and mutually compensatory roles of alpha-mannosidase II and alpha-mannosidase IIx in N-glycan processing in vivo in mice. Proc. Natl. Acad. Sci. U. S. A. 103, 8983-8988). In the present study, we determined minor but unusual N-glycan structures found in MII/MX double knock-out mice. We identified such N-glycans by a systematic glycomics approach applying a two-dimensional LC mapping database and matrix-dependent selective fragmentation technique in MALDI-TOF/TOF MS, a highly sensitive and reliable technique that provides specific fragmentations enabling the determination of precise oligosaccharide structures including regioisomers (Kurogochi, M., and Nishimura, S.-I. (2004) Structural characterization of N-glycopeptides by matrix-dependent selective fragmentation of MALDI-TOF/TOF tandem mass spectrometry. Anal. Chem. 76, 6097-6101). Quantitative profiling of all N-glycan structures including minor components from MII/MX nulls, MII nulls, MX nulls, and wild-type mice at embryonic day 15.5 yielded a total of 37 species when structural heterogeneity was reduced by the removal of the sialic acids. Among six unusual N-glycan structures, two glycoforms were novel and were found only in MII/MX double nulls. We characterize such structure as pseudocomplex-type N-glycans. The present study demonstrated that use of the versatile matrix-dependent selective fragmentation method in MALDI-TOF/TOF MS greatly accelerates detailed structural analysis of a trace amount of N-glycans.

A Chemical Proteomics Approach for the Identification of Accessible Antigens Expressed in Human Kidney Cancer

A promising avenue toward the development of more selective anticancer drugs consists in the targeted delivery of bioactive molecules to the tumor environment by means of binding molecules specific to tumor-associated markers. We have used a chemical proteomics approach based on the ex vivo perfusion and biotinylation of accessible structures within surgically resected human kidneys with tumor to gain information about accessible and abundant antigens that are overexpressed in human cancer. This procedure led to the selective labeling with biotin of vascular structures. Biotinylated proteins were purified on streptavidin resin and identified using mass spectrometric methodologies, revealing 637 proteins, 184 of which were only found in tumor specimens and 223 of which were only found in portions of normal kidneys. Immunohistochemical and PCR analysis confirmed that several of the putative cancer antigens identified in this study are indeed preferentially expressed in tumors. In conclusion, we have developed a methodology that allows the identification of accessible biomarkers in human tissues. The tumor-associated antigens identified in this study may be suitable targets for antibody-based anticancer therapies. The experimental approach described here should be applicable to other surgical specimens and to other pathologies as well as to the study of basic physiological and immunological processes.

Forward (Direct) Osmosis: A Novel and Prospective Process for Brine Control

Forward (Direct) Osmosis: A Novel and Prospective Process for Brine ControlThis paper reports the study of a novel process - Forward (Direct) Osmosis (FO) that potentially can be used for brine control. The driving force in the described FO process is provided by a draw solution comprising highly concentrated ammonium bicarbonate or fructose solution. Using a commercially available FO membrane, experiments conducted using a crossflow, flat-sheet membrane cell yielded...Author(s)How Yong NgWanling TangSourceProceedings of the Water Environment FederationSubjectSession 55: Water Reclamation and Reuse: Water Reuse – Membrane Residuals and Reuse DisinfectionDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2006ISSN1938-6478SICI1938-6478(20060101)2006:8L.4345;1-DOI10.2175/193864706783778952Volume / Issue2006 / 8Content sourceWEFTECFirst / last page(s)4345 - 4352Copyright2006Word count220

The Opportunistic Pathogen Toxoplasma gondii Deploys a Diverse Legion of Invasion and Survival Proteins

Host cell invasion is an essential step during infection by Toxoplasma gondii, an intracellular protozoan that causes the severe opportunistic disease toxoplasmosis in humans. Recent evidence strongly suggests that proteins discharged from Toxoplasma apical secretory organelles (micronemes, dense granules, and rhoptries) play key roles in host cell invasion and survival during infection. However, to date, only a limited number of secretory proteins have been discovered, and the full spectrum of effector molecules involved in parasite invasion and survival remains unknown. To address these issues, we analyzed a large cohort of freely released Toxoplasma secretory proteins by using two complementary methodologies, two-dimensional electrophoresis/mass spectrometry and liquid chromatography/electrospray ionization-tandem mass spectrometry (MudPIT, shotgun proteomics). Visualization of Toxoplasma secretory products by two-dimensional electrophoresis revealed approximately 100 spots, most of which were successfully identified by protein microsequencing or matrix-assisted laser desorption ionization-mass spectrometry analysis. Many proteins were present in multiple species suggesting they are subjected to substantial post-translational modification. Shotgun proteomic analysis of the secretory fraction revealed several additional products, including novel putative adhesive proteins, proteases, and hypothetical secretory proteins similar to products expressed by other related parasites including Plasmodium, the etiologic agent of malaria. A subset of novel proteins were re-expressed as fusions to yellow fluorescent protein, and this initial screen revealed shared and distinct localizations within secretory compartments of T. gondii tachyzoites. These findings provided a uniquely broad view of Toxoplasma secretory proteins that participate in parasite survival and pathogenesis during infection.

Endothelial lipase releases saturated and unsaturated fatty acids of high density lipoprotein phosphatidylcholine

We assessed the ability of endothelial lipase (EL) to hydrolyze the sn-1 and sn-2 fatty acids (FAs) from HDL phosphatidylcholine. For this purpose, reconstituted discoidal HDLs (rHDLs) that contained free cholesterol, apolipoprotein A-I, and either 1-palmitoyl-2-oleoylphosphatidylcholine, 1-palmitoyl-2-linoleoylphosphatidylcholine, or 1-palmitoyl-2-arachidonylphosphatidylcholine were incubated with EL- and control (LacZ)-conditioned media. Gas chromatography analysis of the reaction mixtures revealed that both the sn-1 (16:0) and sn-2 (18:1, 18:2, and 20:4) FAs were liberated by EL. The higher rate of sn-1 FA cleavage compared with sn-2 FA release generated corresponding sn-2 acyl lyso-species as determined by MS analysis. EL failed to release sn-2 FA from rHDLs containing 1-O-1'-hexadecenyl-2-arachidonoylphosphatidylcholine, whose sn-1 position contained a nonhydrolyzable alkyl ether linkage. The lack of phospholipase A(2) activity of EL and its ability to liberate [(14)C]FA from [(14)C]lysophosphatidylcholine (lyso-PC) led us to conclude that EL-mediated deacylation of phosphatidylcholine (PC) is initiated at the sn-1 position, followed by the release of the remaining FA from the lyso-PC intermediate. Thin-layer chromatography analysis of cellular lipids obtained from EL-overexpressing cells revealed a pronounced accumulation of [(14)C]phospholipid and [(14)C]triglyceride upon incubation with 1-palmitoyl-2-[1-(14)C]linoleoyl-PC-labeled HDL(3), indicating the ability of EL to supply cells with unsaturated FAs.

Condensation reactions and formation of amides, esters, and nitriles under hydrothermal conditions.

Hydrothermal pyrolysis experiments were performed to assess condensation (dehydration) reactions to amide, ester, and nitrile functionalities from lipid precursors. Beside product formation, organic compound alteration and stability were also evaluated. Mixtures of nonadecanoic acid, hexadecanedioic acid, or hexadecanamide with water, ammonium bicarbonate, and oxalic acid were heated at 300 degrees C for 72 h. In addition, mixtures of ammonium bicarbonate and oxalic acid solutions were used to test the abiotic formation of organic nitrogen compounds at the same temperature. The resulting products were condensation compounds such as amides, nitriles, and minor quantities of N-methylalkyl amides, alkanols, and esters. Mixtures of alkyl amide in water or oxalic acid yielded mainly hydrolysis and dehydration products, and with ammonium bicarbonate and oxalic acid the yield of condensation products was enhanced. The synthesis experiments with oxalic acid and ammonium bicarbonate solutions yielded homologous series of alkyl amides, alkyl amines, alkanes, and alkanoic acids, all with no carbon number predominances. These organic nitrogen compounds are stable and survive under the elevated temperatures of hydrothermal fluids.