Flotation mechanism of octylic hydroxamic acid on diaspore

Bauxite resources are widely spread in the earth. However, the effective utilization of this mineral is still under infant. The conventional collector for diaspore mineral is oleic acid. It has three main drawbacks which are highly insoluble, large dosages in bauxite flotation, and low selectivity, which hinder its application in industry. In this research, octylic hydroxamic acid was synthesized, and its collecting ability toward two major minerals in bauxite-diaspore and kaolinite was investigated. The collecting power of various reagents for diaspore are shown as follows: oleic acid<octylic hydroxamic acid; while the collecting power for kaolinite was like this: octylic hydroxamic acid<oleic acid. It is shown that octylic hydroxamic acid has the capability of high collectivity and good selectivity. The optimum pH was determined to be 8 9. Zeta potential test revealed that the anionic collectors-octylic hydroxamic acid and oleic acid had been adsorbed on the surface of diaspore and kaolinite, meanwhile the adsorption for diaspore was more remarkable. By the adsorptive capability and IR tests, the adsorption of octylic hydroxamic acid on diaspore was determined to be a process of chemical absorption, which was greater than that of oleic acid.

Action mechanism of octylic hydroxamic acid on diaspore

The conventional collector for diaspore mineral is oleic acid,which is highly insoluble and must be used in high dosage in bauxite flotation,that is the great drawback of oleic acid in use.Octylic hydroxamic acid was synthesized,and its collecting ability to certain minerals in bauxite:diaspore and kaolinite were studied.The collecting power of various reagents to diaspore in an incremental sequence was shown as follows:oleic acid<octylic hydroxamic acid,while the incremental sequence of the collecting power to kaolinite was like this:octylic hydroxamic acid < oleic acid.It could be seen that octylic hydroxamic acid had the capability of high collectivity and good selectivity,and octylic hydroxamic acid was chosen to use in the following experiments.Reduced zeta potential showed the adsorption of the anionic collector on the mineral.By the adsorptive capability and IR(infrared ray)tests,the adsorption of octylic hydroxamic acid on diaspore was determined to be chemical absorption,which was greater than that of oleic acid,as it was absorption by hydrogen bond.

Histone deacetylase inhibitor suberoylanilide hydroxamic acid alleviates liver fibrosis by suppressing the transforming growth factor-β1 signal pathway

Background: Histone deacetylases(HDACs) inhibitors are new anti-fibrotic drugs that inhibit the activity of hepatic stellate cells. The present study focused on the anti-fibrotic function of HDAC inhibitor suberoylanilide hydroxamic acid(SAHA) by suppressing transforming growth factor-β1(TGF-β1) signaling. Methods: Male Sprague-Dawley rats were used to induce liver fibrosis with carbon tetrachloride(CCl 4) and LX2 cell(human hepatic stellate cell line) was stimulated by TGF-β1. Both animals and cells were treated with SAHA. The Smad7 and connective tissue growth factor(CTGF) mRNA levels were detected by real-time polymerase chain reaction(PCR). Western blotting was used to examine the protein levels of CTGF, Histone H3(H3), Smad7, Smad2/3, Acetyl-Histone H3(AH3), HDAC2, α-smooth muscle actin( α-SMA), HDAC6, p-Smad2/3 and HDAC8. In addition, the TGF-β1 and liver enzyme levels from rat serum were detected. Histopathological changes were examined by hematoxylin and eosin(HE), Sirius red and Masson trichrome staining. The α-SMA expression was detected by immumohistochemical staining. Results: Compared with control group, the TGF-β1 and liver enzyme levels from rat serum, together with the mRNA levels of CTGF and protein levels of CTGF, HDAC2, α-SMA, HDAC6, p-Smad2/3 and HDAC8 were elevated in fibrotic rats( P < 0.01). But the Smad7 mRNA and AH3 protein levels were notably suppressed in the fibrotic rats( P < 0.01). Pathological examination showed the typical changes of liver fibrosis in the fibrotic rats. After the treatment with SAHA, the levels of liver enzymes, TGF-β1, CTGF, HDAC2, α-SMA, HDAC6, p-Smad2/3 and HDAC8 were reduced( P < 0.01) and Smad7 and AH3 protein contents were elevated in liver fibrotic rats( P < 0.01). Moreover, immumohistochemistry showed that SAHA significantly suppressed the α-SMA protein content in fibrotic liver( P < 0.01). Conclusion: The HDAC inhibitor SAHA alleviated liver fibrosis by suppressing the TGF-β1 signaling.

Extraction Separation of Germanium with Hydroxamic Acid HGS98

The extraction separation of germanium from indium raffinate in hydrometallurgical zinc process was discussed. The conditions and mechanism of the extraction with hydroxamic acid HGS98 have been investigated in detail. The results show that u sing 2% (mass fraction) hydroxamic acid HGS98 and 5% D 2EHPA as synergist, germanium is extracted (1 stage) over 99% in 5 min at phase ratio ( V o∶ V a) of 1∶5 from indium raffinate with original acidity. Then, using 2 mol·L -1 NH 4F as strip liquor, the stripping recovery is over 98% in 15 min at phase ratio of 1∶1. This process has the following advantages:easy to operate, high recovery and selectivity, and lower investment cost. It provides a new way to recover rare metal-germanium from metallurgical spent residues.

Flotation performance of anisic hydroxamic acid as new collector for tungsten and tin minerals

In order to improve the recovery of tungsten ores containing tin minerals,anisic hydroxamic acid(p-methoxy benzohydroxanic acid,PMOB)was synthesized and introduced as novel collector in the flotation of scheelite,wolframite and cassiterite.The flotation performance and adsorption mechanism were investigated by micro/batch flotation,zeta potential measurements and density functional theory(DFT).The micro flotation results showed that the recoveries of scheelite,wolframite and cassiterite using PMOB as collector are 97.45%,95.77% and 90.08%,respectively,and the corresponding recoveries are 91.00%,84.30% and 84.67% for benzohydroxamic acid(BHA).The batch flotation results revealed that the collector dosage could be reduced by about 45% for PMOB compared with BHA,in the case of similar flotation indicators.Zeta potential measurements indicated that PMOB could be adsorbed on the mineral surfaces by chemisorption.Moreover,density functional theory(DFT)calculation results showed that the substituent group—OCH_(3)endues PMOB stronger electron donation ability and hydrophobicity compared with benzohydroxamic acid(BHA),pmethyl benzohydroxamic acid(PMB)and p-hydroxyl benzohydroxamic acid(PHB).

Studies of benzyl hydroxamic acid/calcium lignosulphonate addition order in the flotation separation of smithsonite from calcite

Flotation separation of smithsonite from calcite is difficult due to their similar surface properties.In the present study,a reagent scheme of depressant calcium lignosulphonate(CLS) and collector benzyl hydroxamic acid(BHA) was introduced in the flotation of smithsonite from calcite.Microflotation tests revealed that the efficient flotation of smithsonite from calcite could only be obtained with the addition order of BHA before CLS,which was opposite to the widely-used order that adding depressant prior to the collector.The zeta potential measurements indicated that BHA selectively adsorbed onto smithsonite surface,then not allowed the CLS adsorption onto the smithsonite surface rather than calcite surface because of the steric hindrance,thereby the smithsonite surface remained hydrophobic while calcite surface became more hydrophilic after the addition of CLS.As a result,the calcite flotation was completely depressed while the smithsonite flotation recovery was still in high value,leading to the optimal flotation separation performance.

Effect of hydroxamic acid polymers on reverse flotation of bauxite

The effect of hydroxamic acid starch (HAS) and hydroxamic acid polyacrylamide (HPAM) on the flotation of diaspore and kaolinite was investigated by flotation test. It is found that HAS depresses diaspore but activates kaolinite in acidic pulp,while HPAM activates both diaspore and kaolinite in the pH range of 2.010.5. The measurement of zeta potential shows that both HAS and HPAM can increase zeta potential of negatively charged diaspore, which indicates the existence of chemical bonding or hydrogen bonding between the reagents and diaspore. By covering the collector dodecyl amine(DDA) on diaspore surface,HAS increases the hydrophilicity of minerals and depresses the flotation of diaspore,however HPAM activates the flotation of diaspore by increasing the adsorption of DDA on diaspore surface.

Synthesis and spectroscopic characterization of fluorescent solid rare-earth complexes with hydroxamic acids

The complexes RE_2(DHYA)_3 centre dot nH_2O in the title bar were synthesizedthrough some reactions of trivalent rare-earth ions. In the process of synthesis, dihydroxamicacids were taken as ligands while the alcohol was taken as a solvent. The ligands includedadipylhydroxamic acid (ADHA), p-phthalichydroxamic acid (PPHA), oxalohydroxamic acid (OXHA),butadihydroxamic acid (BDHA), o-phthalichydroxamic acid (OPHA), benzoylhydroxamic acid (BHA), etc.Measured at 25 deg C, the molar conductances in various modes are 13.00-21.05 S centre dot cm^2centre dot mol^(-1), which shows that rare-earth complexes are nonelectrolytes and the hydroxaminogroups of the complexes have taken part in bonding. Infrared spectra, ultraviolet spectra, nuclearmagnetic resonance (~1HNMR) spectra, and fluorescence spectra were used to investigate thecomplexes. Experiments have proved that the complexes of En^(3+)and Tb^(3+) with aromatic hydroxamicacids have good fluorescent characteristics.

Preparation of cinnamic hydroxamic acid collector and study on flotation characteristics and mechanism of scheelite

In this paper,using methyl cinnamate as raw material,the new cinnamic hydroxamic acid collector(CIHA)was synthesized by the hydroxylamine method.The collector performance of hydroxamic acid was investigated for scheelite and gangue calcite,and the flotation separation test of scheelite and calcite was carried out with CIHA as the collector.The interaction mechanism between hydroxamic acid and scheelite minerals has also been investigated through zeta potential,Fourier transform infrared spectroscopy(FTIR)experiments,X-ray photoelectron spectroscopy(XPS)experiments,and density functional theory(DFT)calculation.The single mineral flotation test and artificially mixed ore showed that CIHA had an excellent collection effect and selectivity.Zeta potential,FTIR,and XPS showed that CIHA was adsorbed on the scheelite surface by strong chemical adsorption.The active group of CIHA was analyzed through quantum chemical calculation.It was speculated that C=O and N-O bonds could synthesize a five-membered chelated hydroxamic acid group with Ca element chelate on scheelite surface,changing hydrophobicity and making it more likely to emerge from the pulp.

Extraction of Zr(IV) from hydrochloric acid with tri-octyl amine and Cyanex 921 in kerosene

This article reports the extraction of zirconium （IV） from aqueous HC1 solution by tri-octyl amine （TOA）, Cyanex 921, and their binary mixture using kerosene as the diluent. The effect of some parameters on the extraction of Zr（IV） was investigated such as equilibration time, aqueous phase acidity, extractant molarity, chloride ion concentration, nature of diluents, and temperature. The extraction of Zr（IV） was found to be 99% from 7.5 M HC1 using the mixture of extractants containing 0.1 M TOA and 0.02 M Cyanex 921 in kerosene. Kerosene was found to be the effective diluent for the extraction of Zr（IV） with the binary mixture of TOA and Cyanex 921. The positive enthalpy change and positive entropy change in the binary extraction system show the endothermic process with an increase in entropy. Stripping of Zr（IV） from the loaded organic phase containing the mixture of TOA （0.1 M） and Cyanex 921 （0.02 M） indicates that HNO3 and Na2CO3 are the best stripping agents.

Enhanced osteogenic differentiation of human periodontal ligament stem cells by suberoylanilide hydroxamic acid

Periodontitis is a type of chronic inflammation in the gingival tissue caused by infectious bacteria colonizing the surface of the teeth,leading to the destruction of tooth-supporting tissues and loss of alveolar bone.Suberoylanilide hydroxamic acid(SAHA),a class of histone deacetylase(HDAC)inhibitor,has the potential to stimulate osteoblast differentiation by acetylating histone proteins,and thus suppressing the expression of adipogenic and chondrogenic genes.However,the effect of SAHA on the differentiation of human periodontal ligament stem cells(hPDLSCs)is yet to be elucidated.Herein,we investigated the effects of SAHA on in vitro proliferation and differentiation of hPDLSCs by MTT assay,Alizarin Red-S,and alkaline phosphatase staining,and real-time PCR.Notably,300 ng/mL SAHA treatment enhanced the proliferation and mineralization of hPDLSCs,indicating their osteogenic potential.Moreover,a significant enhancement of osteogenesis gene markers and proteins was observed.We also demonstrated that ERK is a positive regulator of Runx2 transcription factors during osteoblast differentiation.These results indicate that SAHA may be a useful osteogenic induction agent for periodontal bone regeneration.

Extraction Separation of Scandium，Iron and Lutetium with Isopropyl Phosphonic Acid Mono（1－hexyl－4－ethyl）OctylEster

The extraction and stripping of scandium from its sulfate solutions by isopropyl phosphonic acid mono (1-hexyl-4-ethyl) octyl ester (PT-2, HL) diluted with n-hexane are reported. A high efficiency of separation between scandium, iron and lutetium can be achieved by controlling aqueous acidity. Different mechanisms of Sc3+ with PT-2 in various acid range have been proposed.At lower aqueous acidity, it is a cation exchange reaction, while at higher acidity. a solvation reaction was ascertained. Its IR and NMR spectra have been discussed. The effect of temperature on extraction of Sc3+ was observed and thermodynamic functions were calculated.

Effect of hydroxamic acid starch on reverse flotation desilicate from diasporic bauxite

It is important to depress diaspore effectively in order to remove silicates from diasporic bauxite. A new water soluble polymer hydroxamic acid starch (HA-starch) was prepared. The effects of the product on the diaspore and kaolinite flotation were investigated and its reactive mechanism was studied by zeta potential measurement and FTIR. The results show that HA-starch can depress diaspore while make positive effect on kaolinite flotation at low pH value(pH below 6). The flotation recovery of diaspore was sharply decreased with the increase of concentration of HA-starch. The chemical adsorption of HA-starch on the surface of diaspore was revealed.

Synthesis of a Novel Chiral Trihydroxamic Acid Containing L-Pro-L-Ala-L-Ala-β-(HO)Ala-OMe Unit

An N-hydroxyl peptide unit of H-L-Pro-L-Ala-L-Ala-β-（BnO）Ala-OMe was synthesized by stepwise chain building method in solution. Then, based on nitrilotriacetic acid backbone and this N-hydroxyl peptide unit, a novel chiral tripodal ligand P as an analogue of desferrichrome, has been synthesized. In neutral pH, ligand P formed stable tri（hydroxamato）- iron（Ⅲ） complexes which showed a maximum absorptiota （∑max=2750 M^-lcm^-1） at 422 nm in UV-Vis spectra. The characteristic absorption spectra are similar to those of natural trihydroxamate-type siderophores.

Synthesis and Crystal Structure of 2,2'-Dihydroxy-[1,1']binaphthalenyl-3,3'-bis-hydroxamic Acids

The first synthesis and structural characterization by X-ray crystallography of racemic 2,2＇-dihydroxy-[1,1＇]binaphthalenyl-3,3＇-bis-hydroxamic acids were reported.The com-pound（C28H30N4O8,Mr = 550.56） crystallizes in orthorhombic system,Fdd2 space group with a = 13.055（3）,b = 34.871（7）,c = 12.570（3） ,V = 5722（2） 3,Z = 8,Dc = 1.278 g/cm3,λ = 0.71073 ,μ（MoKα） = 0.095 mm-1,F（000） = 2320,S = 1.021,R = 0.0349 and wR = 0.0802 for 1757 observed reflections with I 〉 2σ（I）.The N-H and O atom are involved in two-dimensional intermolecular hydrogen bond nets,which further stabilize the structure.

Syntheses, Structures, and Luminescent Properties of the ZnⅡ and CdⅡ 1-D Chain Polymers Assembled by Salicylhydroxamic Acid

TWO complexes of compositions [Zn（H2shi）（CHsCOO）]. （1） and [Cd（H2shih（H20）]. （2） （H3shi = salicylhydroxamic acid） have been prepared under solvothermal conditions. They are characterized by X-ray single-crystal diffraction, IR and elemental analysis. The crystal of 1 belongs to the tetragonal system, space group I41/a with a = 18.972（3）, b = 18.972（3）, c = 10.938（2） A, V= 3937.1（I） A3, C9H9NOsZn, Mr - 276.54, Z = 16, Dc = 1.866 g/cm3,μ = 2.500 mm-1, F（000） = 2240, the final R = 0.0425 and wR = 0.123. The crystal of 2 belongs to the monoclinic system, space group P2/c with a = 16.647（3）, b = 6.4577（I）, c = 6.5623（I） A, V = 702.4（2） A3, C14H4Cd2N2OT, Mr = 434.68, Z = 2, Dc = 2.055 g/cm3,μ = 1.599 mm-1, F（000） = 432, the final R = 0.0211 and wR = 0.0761. They both possess I-D polymeric chain structures. The luminescent properties of complexes I and 2 have been investigated.

DFT Study, Linear and Nonlinear Multiple Regression in the Prediction of HDAC7 Inhibitory Activities on a Series of Hydroxamic Acids

In this work, we conducted a QSAR study on 18 molecules using descriptors from the Density Functional Theory (DFT) in order to predict the inhibitory activity of hydroxamic acids on histone deacetylase 7. This study is performed using the principal component analysis (PCA) method, the Ascendant Hierarchical Classification (AHC), the linear multiple regression method (LMR) and the nonlinear multiple regression (NLMR). DFT calculations were performed to obtain information on the structure and information on the properties on a series of hydroxamic acids compounds studied. Multivariate statistical analysis yielded two quantitative models (model MLR and model MNLR) with the quantum descriptors: electronic affinity (AE), vibration frequency of the OH bond (ν(OH)) and that of the NH bond (ν(NH)). The LMR model gives statistically significant results and shows a good predictability R2 = 0.9659, S = 0.488, F = 85 and p-value . Electronic affinity is the priority descriptor in predicting the activity of HDAC7 inhibitors in this study. The results obtained suggest that the descriptors derived from the DFT could be useful to predict the activity of histone deacetylase 7 inhibitors. These models were evaluated according to the criteria of Tropsha et al.

Suberoylanilide hydroxamic acid upregulates reticulophagy receptor expression and promotes cell death in hepatocellular carcinoma cells

BACKGROUND Hepatocellular carcinoma(HCC)is a common clinical condition with a poor prognosis and few effective treatment options.Potent anticancer agents for treating HCC must be identified.Epigenetics plays an essential role in HCC tumorigenesis.Suberoylanilide hydroxamic acid(SAHA),the most common histone deacetylase inhibitor agent,triggers many forms of cell death in HCC.However,the underlying mechanism of action remains unclear.Family with sequence similarity 134 member B(FAM134B)-induced reticulophagy,a selective autophagic pathway,participates in the decision of cell fate and exhibits anticancer activity.This study focused on the relationship between FAM134B-induced reticulophagy and SAHA-mediated cell death.AIM To elucidate potential roles and underlying molecular mechanisms of reticulophagy in SAHA-induced HCC cell death.METHODS The viability,apoptosis,cell cycle,migration,and invasion of SAHA-treated Huh7 and MHCC97L cells were measured.Proteins related to the reticulophagy pathway,mitochondria-endoplasmic reticulum(ER)contact sites,intrinsic mitochondrial apoptosis,and histone acetylation were quantified using western blotting.ER and lysosome colocalization,and mitochondrial Ca^(2+)levels were characterized via confocal microscopy.The level of cell death was evaluated through Hoechst 33342 staining and propidium iodide colocalization.Chromatin immunoprecipitation was used to verify histone H4 lysine-16 acetylation in the FAM134B promoter region.RESULTS After SAHA treatment,the proliferation of Huh7 and MHCC97L cells was significantly inhibited,and the migration and invasion abilities were greatly blocked in vitro.This promoted apoptosis and caused G1 phase cells to increase in a concentration-dependent manner.Following treatment with SAHA,ER-phagy was activated,thereby triggering autophagy-mediated cell death of HCC cells in vitro.Western blotting and chromatin immunoprecipitation assays confirmed that SAHA regulated FAM134B expression by enhancing the histone H4 lysine-16 acetylation in the FAM134B promoter region.Further,SAHA disturbed the Ca^(2+)homeostasis and upregulated the level of autocrine motility factor receptor and proteins related to mitochondria-endoplasmic reticulum contact sites in HCC cells.Additionally,SAHA decreased the mitochondrial membrane potential levels,thereby accelerating the activation of the reticulophagy-mediated mitochondrial apoptosis pathway and promoting HCC cell death in vitro.CONCLUSION SAHA stimulates FAM134B-mediated ER-phagy to synergistically enhance the mitochondrial apoptotic pathway,thereby enhancing HCC cell death.

Production of octyl levulinate biolubricant over modified H-ZSM-5:Optimization by response surface methodology

The present study highlighted the use of modified H-ZSM-5 （Meso-HZ-5） as heterogeneous catalyst for the synthesis of octyl levulinate biolubricant by catalytic esterification of biomass derived renewable levulinic acid （LA） with n-octanol. The process variables such as catalyst loading （X1）, n-octanol to LA molar ratio （X2） and reaction temperature （X3） were optimized through response surface methodology （RSM）, using Box-Behnken model. Analysis of variance was performed to determine the adequacy and significance of the quadratic model. The yield of octyl levulinate was obtained to be 99% at optimum process parameters. The developed quadratic model was found to be adequate and statistically accurate with correlation value （R2） of 0.9971 to predict the yield of octyl levulinate biolubricant. The study was also extended on the validation of theoretical and experimental data, including catalyst reusability.

Catalytic Esterification of Medium-Chain Fatty Acids:Kinetic Investigations

Medium-chain fatty acids (MCFA) are straight-chain fatty acids with aliphatic tails of 6 - 12 carbons, which can form medium-chain triglycerides. They are found mostly in animal fats and in the tropical vegetable oils. Because of their wide applications in industry, there is a growing demand of esters of medium-chain fatty acids production. The aim of our work was investigations of the kinetics of the synthesis of esters of MCFA in the presence of dowex catalyst in wide range of process parameters. Hexanoic, octanoic and decanoic acids were esterified with n-octyl alcohol in the presence of sulfuric acid and commercial dowex W50X8 as catalysts in an experimental semi-periodic glass tank reactor with instantaneous and complete water removal. Because of complete removal of water from the reacting mixture, thus eliminating the reverse hydrolysis reaction, the esterification can be assumed as irreversible reaction. The temperature range was 393 - 423 K, the range of initial mole ratio of alcohol to acid was 3 - 10. The kinetic parameters are given. The reaction kinetics appeared to be of the first order with respect to the acid. The effect of temperature on the reaction rate follows the Arrhenius equation well.