Biobased Furfurylated Poplar Wood for Flame-Retardant Modification with Boric Acid and Ammonium Dihydrogen Phosphate

Furfurylated wood exhibits excellent dimensional stability and corrosion resistance,making it a promising material for constructing buildings,but it is highly flammable.Herein,flame-retardant furfurylated poplar wood was produced via a two-step process utilizing boric acid(BA)and ammonium dihydrogen phosphate(ADP)as flame-retardant components,and biomass-derived furfuryl alcohol(FA)as a modifier.The acidity of BA and ADP allowed them to catalyze the polymerization of FA,which formed a cross-linked network that immobilized BA and ADP inside the wood.The addition of BA/ADP substantially delayed the time to ignition from 10 to 385 s and reduced the total heat release and total smoke release by 58.75%and 77.31%,respectively.Analysis of the pyrolysis process showed that the decomposition products of BA and ADP protected the underlying furfurylated wood and diluted combustible gases.This method significantly improved the fire retardancy and smokeless properties of furfurylated wood,providing promising prospects for its application as an engineering material.

Molecular Dynamics Study on Configuration Energy and Radial Distribution Functions of Ammonium Dihydrogen Phosphates Solution

Molecular dynamics simulations were carried out to study the configuration energy and radial distribution functions of mmonium dihydrogen phosphate solution at different temperatures. The dihydrogen phosphate ion was treated as a seven-site model and the ammonium ion was regarded as a five-site model, while a simple-point-charge model for water molecule. An unusually local particle number density fluctuation was observed in the system at saturation temperature. It can be found that the potential energy increases slowly with the temperature from 373 K to 404 K, which indicates that the ammonium dihydrogen phosphate has partly decomposed. The radial distribution function between the hydrogen atom of ammonium cation and the oxygen atom of dihydrogen phosphate ion at three different temperatures shows obvious difference, which indicates that the average H-bond number changes obviously with the temperature. The temperature has an influence on the combination between hydrogen atoms and phosphorus atoms of dihydrogen phosphate ion and there are much more growth units at saturated solutions.

Molecular Dynamics Study on Microstructure of Potassium Dihydrogen Phosphates Solution

Molecular dynamics simulations were carried out to study the internal energy and microstructure of potassium dihydrogen phosphates （KDP） solution at different temperatures. The water molecule was treated as a simple-point-charge model, while a seven-site model for the dihydrogen phosphate ion was adopted. The internal energy functions and the radial distribution functions of the solution were studied in detail. An unusually large local particle number density fluctuation was observed in the system at saturation temperature. It has been found that the specific heat of oversaturated solution is higher than that of unsaturated solution, which indicates the solution experiences a crystallization process below saturation temperature. The radial distribution function between the oxygen atom of water and the hydrogen atom of the dihydrogen phosphate ion shows a very strong hydrogen bond structure. There are strong interactions between potassium cation and oxygen atom of dihydrogen phosphate ion in KDP solution, and much more ion pairs were formed in saturated solution.

Subsurface Damage in Scratch Testing of Potassium Dihydrogen Phosphate Crystal

Potassium dihydrogen phosphate （KDP） is an important electro-optic crystal, often used for frequency conversion and Pockels cells in large aperture laser systems. To investigate the influence of anisotropy to the depth of subsurface damage and the profiles of cracks in subsurface of KDP crystal, an experimental study was made to obtain the form of subsurface damage produced by scratches on KDP crystal in [100], [120] and [110] crystal directions on （001） crystal plane. The results indicated that there were great differences between depth and crack shape in different directions. For many slip planes in KDP, the plastic deformation and cracks generated under pressure in the subsurface were complex. Fluctuations of subsurface damage depth at transition point were attributed to the deformation of the surface which consumed more energy when the surface deformation changed from the mixed region of brittle and plastic to the complete brittle region along the scratch. Also, the process of subsurface damage from shallow to deep, from dislocation to big crack in KDP crystal with the increase of radial force and etch pit on different crystal plane were obtained. Because crystallographic orientation and processing orientation was different, etching pits on （100） crystal plane were quadrilateral while on （110） plane and （120） plane were trapezoidal and triangular, respectively.

Silica supported ammonium dihydrogen phosphate(NH_4H_2PO_4/SiO_2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes

catalyst for the synthesis of 14-aryl- 14-H-dibenzo[aj]xanthenes Silica supported ammonium dihydrogen phosphate （NH4H2PO4/SiO2） is found to be a recyclable heterogeneous catalyst for a rapid and efficient synthesis of various aryl-14-H-dibenzo[a,j]xanthenes with excellent yields under solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times and milder conditions. 2009 Shahnaz Rostamizadeh. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Potassium dihydrogen phosphate catalyzed one-pot synthesis of 2,4,5-triaryl-1H-imidazoles

A simple and efficient method has been developed;benzil/benzoin undergoes smooth condensation with various substituted aldehyde and ammonium acetate in the presence of potassium dihydrogen phosphate（KH;PO;） under mild reaction conditions to afford the corresponding trisubstituted imidazole in excellent yields.The method for synthesis of product,the reaction mixture was reflux in ethanol for 40-90 min.The present method is simple,efficient,and cost-effective.

One-pot synthesis of tri- and tetra-substituted imidazoles using sodium dihydrogen phosphate under solvent-free conditions

Sodium dihydrogen phosphate （NaH2PO4） efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.

Characteristics of Laser-Induced Surface and Bulk Damage of Large-Aperture Deuterated Potassium Dihydrogen Phosphate at 351 nm

Deuterated potassium dihydrogen phosphate damage performance at 351 nm is studied on a large-aperture laser system. Bulk and rear-surface damage are initiated under the 3ω fluences of 6.T J/cm2 and 33/cm2, and show different growth characteristics under multiple laser irradiations with the fluence of 6 J/cm2. The size and number of bulk damage keep unchanged once initiated. However, surface damage size also does not grow, while surface damage number increases linearly with laser shots. Different damage thresholds and growth behaviors suggest different formations of bulk and surface damage precursors. The cause of surface damage is supposed to be near-surface absorbing particles buried under the sol-gel coating.

Solubility and solution thermodynamics of ammonium dihydrogen phosphate in the water–methanol system

The solubility of ammonium dihydrogen phosphate(MAP)in the water–methanol system is essential for antisolvent crystallization studies.To investigate the effect of methanol on the solubility of MAP in water,the solubility of MAP in the water–methanol system was determined by dynamic method and static equilibrium method at temperatures ranging from 293.2 to 343.2 K at atmospheric pressure.Results showed that the solubility of MAP increased with the increase of temperature and the increase of water mole fraction in the water–methanol system.The experimental solubility data were correlated with the modified Apelblat equation,the combined nearly ideal binary solvent/Redlich–Kister(CNIBS/R–K)model and the Jouyban–Acree model.The calculated results based on these three models were in very good agreement with the experimental data with the average relative deviations of 0.65%,0.97%,and 5.38%,respectively.Simultaneously,the thermodynamic properties of the MAP dissolution process in the water–methanol system,including Gibbs energy change,enthalpy,and entropy were obtained by the Van’t Hoff equation,which can be used to assess the crystallization process.

A ten-fold coordinated high-pressure structure in hafnium dihydrogen with increasing superconducting transition temperature induced by enhancive pressure

High pressure is an effective method to induce structural and electronic changes,creating novel high-pressure structures with excellent physical and chemical properties.Herein,we investigate the structural phase transition of hafnium dihydrogen(HfH2)in a pressure range of 0 GPa-500 GPa through the first-principles calculations and the crystal structure analysis by particle swarm optimization(CALYPSO)code.The high-pressure phase transition sequence of HfH2is I4/mmm→Cmma→P-3m1 and the two phase transition pressure points are 220.21 GPa and 359.18 GPa,respectively.A newly trigonal P-3m1 structure with 10-fold coordination first appears as an energy superior structure under high pressure.These three structures are all metallic with the internal ionic bonding of Hf and H atoms.Moreover,the superconducting transition temperature(Tc)values of Cmma at 300 GPa and P-3m1 at 500 GPa are 3.439 K and 19.737 K,respectively.Interestingly,the superconducting transition temperature of the P-3m1 structure presents an upward trend with the pressure rising,which can be attributed to the increase of electron-phonon coupling caused by the enhanced Hf-d electronic density of states at Fermi level under high pressure.

Theoretical Study on Dihydrogen Bonds of NH3BH3 with Several Small Molecules

The dihydrogen bonds B-H...H-X （X= the complexes of NH3BH3 with HF, HCl, F, Cl, Br, C, O, N） in the dimer （NH3BH3）2 and HBr, H2CO, H20, and CH3OH were theoretically studied. The results show that formation of the dihydrogen bond leads to elongation and stretch frequency red shift of the BH and XH bonds, except that in the H2CO system, the CH bond blue shifts. For （NH3BH3）2 and the complexes of the halogenides, red shifts of the XH bonds are caused by the intermolecular hyperconjugation σ（BH）→σ^＊ （XH）. For the system of H2CO, a blue shift of the CH bond is caused by a decrease of the intramolecular hyperconjugation n（O→σ^＊ （CH）. In the other two systems, the red shift of OH bond is a secondary effect of the stronger traditional red-shifted H-bonds N-H... O. In all these systems, red shifts of the BH bonds are caused by two factors： negative repolarization and negative rehybridization of the BH bond, and decrease of occupancy on σ（BH） caused by the intermolecular hyperconjugation σ（BH）→σ^＊ （XH）.

Electrical Conduction in Deuterated Ammonium Dihydrogen Phosphate Crystals with Different Degrees of Deuteration

Conductivity measurements of deuterated ammonium dihydrogen phosphate （DADP） crystals with different deuterated degrees are described. The conductivities increase with the deuterium content, and the value of the a-direction is larger than that of the e-direction. Compared with DKDP crystals, DADP crystals have larger conductivities, which is partly due to the existence of A defects. The ac conductivity over the temperature range 25-170℃has shown a knee in the curve ofln（σT） versus T-1. The conductivity activation energy calculated by the slope of the high temperature region decreases with the deuterium content. The previously reported phase transition is not seen.

The Antiproliferative and Pro-apoptotic Role of 2-aminoethyl dihydrogen Phosphate in Triple-negative Breast Tumor Cells

Antineoplastic phospholipids are a new class of antitumor agents.These molecules interact with the plasma membrane,changing numerous pathways that induce cell death,with high selectivity for cancer cells.A representative of this class of antineoplastic agents is 2-aminoethyl dihydrogen phosphate(2-AEH2P).It is present in high intracellular concentrations in various tissues and organelles with antitumor,antiproliferative and pro-apoptotic action.Therefore,4T1 triple-negative tumor cells were treated in different concentrations in order to assess the cytotoxic potential and its effects on the modulation of cell death pathways in association with the chemotherapeutic drug Paclitaxel.2-AEH2P promoted cytotoxicity in tumor cells and significant morphological changes,however,it did not cause these effects in normal cells.There was positive regulation of proteins involved in the intrinsic pathway of cell death by apoptosis and regulation of the phases of cell cycle progression.Furthermore,structural and distribution changes in mitochondria,as well as decreased cell density and regression of the cytoskeleton were observed.The 2-AEH2P demonstrated a modulatory potential of apoptotic pathways inducing cell death,being a new compound with antitumor properties.

Effect of different operation conditions on PCDD/F inhibition by ammonium dihydrogen phosphate:concentrations,distributions and mechanisms

Phosphorus-containing compounds are considered as the potential alternatives of traditional inhibitors for suppressing the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs),but the suppression characteristics are scarcely studied.In this study,ammonium dihydrogen phosphate(ADP)was selected as the inhibitor to inhibit the PCDD/F formation via de novo synthesis at 350℃.The influence of oxygen content and addition method on PCDD/F inhibition was systematically investigated by means of statistical analysis and morphological characterization.The results showed that oxygen enhanced the formation of PCDD/Fs from 1470 ng g^(−1)(9.78 ng I-TEQ g^(−1))to 2110 ng g^(−1)(14.8 ng I-TEQ g^(−1)).ADP significantly inhibited the PCDD/F formation,with inhibition efficiencies ranging from 82.0%to 97.7%.Herein,a higher oxygen content and the premixed way intensified the suppression effect.Dibenzo-p-dioxin(DD)/dibenzofuran(DF)chlorination was proven to be effectively suppressed while chlorophenol(CP)route was not obviously influenced.With the addition of ADP,Cl source was significantly reduced and the formation of organic Cl was effectively inhibited.Also,it decreased the proportion of C–O/C=N and C=O,revealing the efficient inhibition of carbon oxidation.Meanwhile,the formation of copper phosphate and copper pyrophosphate was observed in XPS(X-ray photoelectron spectroscopy)spectra,indicating that the catalytic metal Cu was chelated and passivated by ADP.The premixed way had a better effect on reducing Cl resources,inhibiting oxidation and chelating metals,due to the direct contact with inhibitor.However,the separation method could only depend on the decomposed gases,resulting in a lower inhibition efficiency.

Does the molecular structure of CaH_2 affect the dihydrogen bonding in CaH_2 HY(Y = CH_3,C_2H_3,C_2 H,CN,and NC) complexes? A quantum chemistry study using MP2 and B3LYP methods

Second-order Maller-Plesset （MP2） and density functional theory （DFT） calculations have been carried out in order to inves- tigate the structures and properties of dihydrogen-bonded CaH2...HY （Y = CH3, C2H3, C2H, CN, and NC） complexes. Our cal- culations revealed two possible structures for Call2 in CaH2..,HY complexes： linear （I） and bent （II）. The bond lengths, interac- tion energies, and strengths for H...H interactions obtained by both MP2 and B3LYP methods are quite close to each other. It was found that the interaction energy decreases with increasing electron density at the Ca-H bond critical point. At- om-in-molecule （AIM） results show that for all of Ca-H...H-Y interactions considered here, the Laplacian of the electron densi- ty at the H--.H bond critical point is positive, indicating the electrostatic nature of these Ca-H...H-Y dihydrogen bonded systems.

High pressure, a protocol to identify the weak dihydrogen bonds:experimental evidence of C–H···H–B interaction

Pressure, as a thermodynamic parameter, provides an appropriate method to detect weak intermolecular interactions. The C–H···H–B dihydrogen bond is so weak that the experimental evidence of this interaction is still limited. A combination of in situ high pressure Raman spectra and angle-dispersive X-ray diffraction(ADXRD) experiments was utilized to explore the dihydrogen bonds in dimethylamine borane(DMAB). Both Raman and ADXRD measurements suggested that the crystal structure of DMAB is stable in the pressure region from 1 atm(1 atm=1.01325×10~5 Pa) to 0.54 GPa. The red shift of CH stretching and CH_3 distortion modes gave strong evidence for the existence of C–H···H–B dihydrogen bonds. Further analysis of Raman spectra and Hirshfeld surface confirmed our proposal. This work provided a deeper understanding of dihydrogen bonds.And we wish that high pressure could be applied to identify other unconfirmed hydrogen or dihydrogen bond.

Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

It has been a tremendous challenge to manu facture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the require ments of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room tem perature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nanoscale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load displacement curves during nanoindentation.

Sensitive fluorescence probes for dihydrogen phosphonate anion based on calix[4]arene bearing naphthol-hydrazone groups

t-Butyl and t-pentylcalix[4]arenes bearing two 2-naphthol-1-hydrazone groups at the lower rim were synthesized,and showed excited-state intermolecular proton transfer fluorescent signal with basic anion.They are more sensitive to dihydrogen phosphate anion than to fluoride anion,although the latter has stronger basicity.Compared with t-butylcalix[4]arene bearing two 2-naphthol-1-hydrazone groups,t-pentylcalix[4]arenes derivative has a larger fluorescent difference between dihydrogen phosphate and fluoride anion.This finding may be used to analyze dihydrogen phosphate anion in the presence of fluoride anion and provide a new approach for designing fluorescence probes that are highly selective for H2PO4-.

Rare-earth mediated dihydrogen activation and catalytic hydrogenation

This review covers H-H bond cleavage of dihydrogen(H2)mediated by structurally well-defined rareearth metal(scandium,yttrium and lanthanides)complexes,and their applications in homogenous catalysis,such as catalytic hydrogenation of unsaturated organic molecules.Depending on the mechanism of the H-H bond cleavage,this review is organized in two parts:(1)σ-bond metathesis,and(2)non-σ-metathesis H2 activation.The latter is a new trend in this research field and is the emphasis of this review.Converting H2 into inorganic rare-earth polyhydride complexes,albeit their potential applications as hydrogen-storage materiel,is not in the scope of this review.

Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals:characterization by nanoindentation

Potassium dihydrogen phosphate(KDP)crystals are widely used in laser ignition facilities as optical switching and frequency conversion components.These crystals are soft,brittle,and sensitive to external conditions(e.g.,humidity,temperature,and applied stress).Hence,conventional characterization methods,such as transmission electron microscopy,cannot be used to study the mechanisms of material deformation.Nevertheless,understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process.This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations.The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals,and dislocation pileup leads to brittle fracture during nanoindentation.Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals,and plastic deformation and brittle fracture are related to the material's anisotropy.However,the E l Ning Hou 13b908074@hit.edu.cn Liang-Chi Zhang liangchi.zhang@unsw.edu.au 1 School of Mechatronics Engineering,Harbin Institute of Technology,Harbin 150001,People's Republic of China 2 School of Mechatronics Engineering,Shenyang Aerospace University,Shenyang 110136.People's Republic of China'Laboratory for Precision and Nano Processing Technologies,School of Mechanical and Manufacturing Engineering,The University of New South Wales,Sydney,NSW 2052,Australia effect of loading rate on the KDP crystal deformation is practically negligible.The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.