Presence Of Diammonium Hydrogen Phosphate Research Articles

Selective adsorption of the activator diammonium hydrogen phosphate in the reverse flotation separation of brucite and dolomite

To achieve efficient purification of brucite resources, diammonium hydrogen phosphate (DAP) was used as an activator to realize the reverse flotation separation of brucite and dolomite in a flotation system with dodecylamine (DDA) as the collector. The microflotation test reveals only a small difference between the flotation recovery of brucite and dolomite in the DDA system. The presence of DAP considerably improve the flotation recovery of dolomite and increase the flotation difference between the two minerals. The adsorption capacity measurements indicate that DAP selectively increase the adsorption capacity of dolomite for DDA but do not affect the adsorption capacity of brucite for DDA. Contact angle measurements reveals that DAP enhances the floatability of dolomite in DDA system and the difference in contact angle between brucite and dolomite. Zeta potential detection and Fourier transform infrared spectroscopy analysis reveal that the strong adsorption of DAP on dolomite is conducive to the adsorption of DDA on the dolomite surface but the presence of DAP do not affect the weak adsorption of DDA on the brucite surface. X-ray photoelectron spectroscopy results reveal that DAP strongly adsorbs on the characteristic Ca sites on the dolomite surface and that DDA has a strong adsorption ability on dolomite after DAP adsorption, which is beneficial for the targeted activation of dolomite flotation.

Thermo-compression process-mediated in-situ cellulose microfibers phosphorylation enables high performant cellulosic paper packaging

With the increasing demand for environmentally friendly alternatives to traditional plastic packaging, the development of sustainable cellulosic-based materials has become a strategic research topic. In this concept, a groundbreaking approach was adopted herein to produce phosphorylated cellulose microfibers (CMFs)-based paper packaging via a one-pot preparation step using a thermo-compression process (150 °C under pression for 45 min) in the presence of diammonium hydrogen phosphate ((NH4)2HPO4, denoted DAP) and urea. This process involves a chemical mechanism leading to the production of phosphorylated cellulosic paper with a very compacted structure induced by the hornification phenomenon. This phenomenon reveals the formation of additional and irreversible strong hydrogen bonds leading thus to an increase of the materials’ crystallinity up to 91%, and to an enhancement of their morphological, thermal stability, flame retardancy, hydrophobicity, water vapor permeability, and mechanical strength properties. To further enhance these properties, and thus their potential applications, the as-produced phosphorylated CMF paper samples were then coated with a thin layer (40 ± 1.11 µm) of poly[ethylene-co-(vinyl acetate)] (EVA) polymer. A comparison of collected properties with those from non-phosphorylated CMFs or from materials prepared using the conventional phosphorylation process clearly demonstrates that the proposed one-pot preparation method led to the production of advanced materials more effective for packaging applications. Overall, the findings associated to this work could be used as a proof-of-concept for the development of sustainable packaging materials, which could be made by following a more efficient and cost-effective manufacturing procedure than current benchmarks.

Stimulation of d- and l-lactate dehydrogenases transcriptional levels in presence of diammonium hydrogen phosphate resulting to enhanced lactic acid production by Lactobacillus strain

The present study revealed the effect of nitrogen sources on lactic acid production and stimulation of d- and l-lactate dehydrogenases (LDH) of parent Lactobacillus lactis NCIM 2368 and its mutant RM2-24 generated after UV mutagenesis. Both the parent and mutant strains were evaluated for d-lactic acid production in control and modified media. The modified media did not show remarkable effect on lactic acid production in case of parent whereas mutant exhibited significant enhancement in d-lactic acid production along with the appearance of l-lactic acid in the broth. Both LDH activities and specific activities were found to be higher in mutant than the parent strain. These results suggested that the diammonium hydrogen phosphate in modified media triggered the expression of LDH genes leading to enhanced lactic acid production. This observation has been proved by studying the expression levels of d- and l-LDH genes of parent and mutant in control and modified media using quantitative RT-PCR technique. In case of mutant, the transcriptional levels of d-LDH and l-LDH increased ∼17 fold and ∼1.38 fold respectively in modified medium compared to the values obtained with control medium. In case of parent, no significant change in transcriptional levels of d- and l-LDH was found when the cells were grown in either control medium or modified medium. This study suggested that the mutant, RM2-24 has l-LDH gene which is expressed in presence of (NH4)2HPO4 resulting in l-lactic acid production. Co-production of l-lactic acid in d-lactic acid fermentation may be detrimental in the PLA production.

Efficient synthesis of 2-amino-4-aryl-8-[(E)-arylmethylidene]-5, 6, 7, 8-4H pyrano [3, 2-c]pyridine in green media

An efficient, general, and atom-economic procedure for the synthesis of 2-amino-6 methyl-4-aryl-8-[(E)-arylmethylidene]-5, 6, 7, 8-4H-pyrano [3, 2-c]pyridine-3-carbonitriles has been developed by reaction of 3,5-bis[(E)-arylmethylidene]-tetrahydro-4(1H)-pyridinones with malononitrile. The reaction proceeds under green media (EtOH/H2O, 1:1) and in the presence of diammonium hydrogen phosphate (10%) or piperidine (10%) to afford pyranopyridines at room temperature with good high yields.

4-Aryl-4H-naphthopyrans derivatives: one-pot synthesis, evaluation of Src kinase inhibitory and anti-proliferative activities

BackgroundA series of 2-amino-4-aryl-4H-benzo[h or f]chromene-3-carbonitrile derivatives were synthesized and evaluated for inhibition of Src kinase and cell proliferation in breast carcinoma (BT-20) cell lines.MethodsThe one-pot, three-component reaction of α or β-naphthol, malonitrile and an aromatic aldehyde in the presence of diammonium hydrogen phosphate was afforded the corresponding 2-amino-4-aryl-4H-benzo[h or f]chromene-3-carbonitrile derivatives, All target compounds were evaluated for inhibition of Src kinase and cell proliferation in breast carcinoma (BT-20) cell lines.ResultsAmong all tested compounds, unsubstituted 4-phenyl analog 4a showed Src kinas inhibitory effect with IC50 value of 28.1 μM and was the most potent compound in this series. In general, the compounds were moderately active against BT-20. 3-Nitro-phenyl 4e and 3-pyridinyl 4h derivatives inhibited the cell proliferation of BT-20 cells by 33% and 31.5%, respectively, and found to be more potent compared to doxorubicin (25% inhibition of cell growth).ConclusionThe data indicate that 4-aryl-4H-naphthopyrans scaffold has the potential to be optimized further for designing more potent Src kinase inhibitors and/or anticancer lead compounds.

Flexible enantioselectivity of tryptophanase attributable to benzene ring in heterocyclic moiety of d-tryptophan.

The invariance principle of enzyme enantioselectivity must be absolute because it is absolutely essential to the homochiral biological world. Most enzymes are strictly enantioselective, and tryptophanase is one of the enzymes with extreme absolute enantioselectivity for L-tryptophan. Contrary to conventional knowledge about the principle, tryptophanase becomes flexible to catalyze D-tryptophan in the presence of diammonium hydrogenphosphate. Since D-amino acids are ordinarily inert or function as inhibitors even though they are bound to the active site, the inhibition behavior of D-tryptophan and several inhibitors involved in this process was examined in terms of kinetics to explain the reason for this flexible enantioselectivity in the presence of diammonium hydrogenphosphate. Diammonium hydrogenphosphate gave tryptophanase a small conformational change so that D-tryptophan could work as a substrate. As opposed to other D-amino acids, D-tryptophan is a very bulky amino acid with a benzene ring in its heterocyclic moiety, and so we suggest that this structural feature makes the catalysis of D-tryptophan degradation possible, consequently leading to the flexible enantioselectivity. The present results not only help to understand the mechanism of enzyme enantioselectivity, but also shed light on the origin of homochirality.

Synthesis of 4‐Aryl‐3‐Methyl‐1‐Phenyl‐1H‐Benzo[h]Pyrazolo[3,4‐b]Quinoline‐5,10‐diones Using Diammonium Hydrogen Phosphate as an Efficient and Versatile Catalyst in Water

AbstractA simple and efficient synthesis of 4‐aryl‐3‐methyl‐1‐phenyl‐1H‐benzo[h]pyrazolo[3,4‐b]quinoline‐5,10‐diones has been accomplished by the one‐pot condensation reaction of 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine, aldehydes and 2‐hydroxynaphthalene‐1,4‐dione in water in the presence of diammonium hydrogen phosphate.

Tryptophanase-catalyzed L-tryptophan synthesis from D-serine in the presence of diammonium hydrogen phosphate.

Tryptophanase, an enzyme with extreme absolute stereospecificity for optically active stereoisomers, catalyzes the synthesis of l-tryptophan from l-serine and indole through a β-substitution mechanism of the ping-pong type, and has no activity on d-serine. We previously reported that tryptophanase changed its stereospecificity to degrade d-tryptophan in highly concentrated diammonium hydrogen phosphate, (NH4)2HPO4 solution. The present study provided the same stereospecific change seen in the d-tryptophan degradation reaction also occurs in tryptophan synthesis from d-serine. Tryptophanase became active to d-serine to synthesize l-tryptophan in the presence of diammonium hydrogen phosphate. This reaction has never been reported before. d-serine seems to undergo β-replacement via an enzyme-bonded α-aminoacylate intermediate to yield l-tryptophan.

Diammonium Hydrogen Phosphate as an Efficient and Inexpensive Catalyst for the Synthesis of Bis(indolyl)methanes under Solvent-Free Conditions

Bis(indolyl)methanes were synthesized by the reaction of indole derivatives and aromatic and aliphatic aldehydes in the presence of diammonium hydrogen phosphate as a solid catalyst under solvent-free conditions. This methodology offers significant improvements for the synthesis of bis(indolyl)methanes with regard to the yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents.

Formation of poly-3-hydroxybutyrate by a soil microbial community during batch and heterocontinuous cultivation

Glucose added to soil as an extracellular source of carbon and energy was proved to be deposited into an intracellular polymer poly-3-hydroxybutyrate (PHB). Untreated soil samples contained PHB amounts corresponding to 1.56 –2.64 μg of crotonic acid per 1 g soil. During batch cultivation after addition of 1 % glucose the PHB content increased by 20-fold after 2 d and then decreased owing to the disappearance of glucose from the soil. Repeated additions of glucose did not bring about any significant increase in PHB content as compared with a single addition. In soil supplied continuously with 0.1 or 0.25 % glucose solution, the content of PHB increased, after an initial lag, gradually up to the 10th day. After 1-d cultivation the content of PHB in the batch system increased even in the presence of diammonium hydrogen phosphate. In a heterocontinuous system no PHB accumulation took place in the presence of this source of nitrogen and phosphorus as long as the C:N ratio of theadded substrate was 10: 1.