Effects of Calcination Temperature of Boron-Containing Magnesium Oxide Raw Materials on Properties of Magnesium Phosphate Cement as a Biomaterial

A new magnesium phosphate bone cement （MPBC） was prepared as a byproduct of boroncontaining magnesium oxide （B-MgO） after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products （KMgPO4.6H2O） of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO （Chinese Pharmacopeia, 2O10 Edition） and for hydroxyapatite surgical implants （GB23101.1-2O08）. The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa＇6H2O, the main hydration product, determined the compressive strength.

Shielding effectiveness of boron-containing ores in Liaoning province of China against gamma rays and thermal neutrons

In this study, the mass attenuation coefficient of boron-containing ores in the Liaoning province of China was calculated using Win XCOM software to investigate the shielding effectiveness of these ores against gamma rays. The mass attenuation coefficients were also calculated using MCNP-4 B code and compared with Win XCOM results; consequently, a good consistency between the results of Win XCOM and MCNP-4 B was observed. Furthermore, the G-P fitting method was used to evaluate the values of exposure buildup factor(EBF) in the energy range of 0.015–15 Me V up to 40 mean free paths. Among the selected ores, boron-bearing iron concentrate ore(M3)was determined to be the best gamma ray shielding ore owing to its higher values of mass attenuation coefficient and equivalent atomic number and lower value of EBF.Moreover, American Evaluated Nuclear Data File(ENDF/B-VII) was used to analyze the shielding effectivenessagainst thermal neutrons. It was determined that Szaibelyite(M2) is the best thermal neutron shielding material.This study would be useful for demonstrating the potential of boron-containing ores for applications in the field of nuclear engineering and technology.

Curing reaction and mechanism of phenol-formaldehyde novolac resins for foundry

In this study on the curing dynamics of phenol-formaldehyde novolac resins(PFNR) and hexamethylene tetramine(HMTA), two typical commercial PFNR were selected as examples and the curing reactions of the resins with HMTA were studied by differential scanning calorimetry(DSC). Based on the data calculated by the Kissinger equation and the Crane equation, a thermocuring dynamic model was established, from which the process conditions, activation energy, reaction kinetics equation and a f irst-order reaction of the curing reactions were derived.

Reinforcement of Lignin-Based Phenol-Formaldehyde Adhesive with Nano-Crystalline Cellulose (NCC): Curing Behavior and Bonding Property of Plywood

The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 and 20&degC/min) and the bonding property was evaluated by the wet shear strength and wood failure of two-ply plywood panels after soaking in water (48 hours at room temperature and followed by 1-hour boiling). The test results indicated that the NCC content had little influence on the peak temperature, activation energy and the total heat of reaction of LPF resin at 5 and 10&degC/min. But at 20&degC/min, LPF0.00% (LPF resin without NCC) showed the highest total heat of reaction, while LPF0.25% (LPF resin containing 0.25% NCC content) and LPF0.50% (LPF resin containing 0.50% NCC content) gave the lowest value. The wet shear strength was affected by the NCC content to a certain extent. With regard to the results of one-way analysis of variance, the bonding quality could be improved by NCC and the optimum NCC content ranged from 0.25% to 0.50%. The wood failure was also affected by the NCC content, but the trend with respect to NCC content was not clear.

Study on binder system of CO_2-cured phenol-formaldehyde resin used in foundry

A new aqueous alkaline resol phenol-formaldehyde resin has been prepared from phenol and formaldehyde using NaOH as catalyst; the optimum synthetic process has been determined. With addition of some cross-linking agents, after passing carbon dioxide gas through the resin bonded sand, high as-gassed strength and 24 h strength are achieved. The bonding bridge of the resin bonded sand fracture has been analyzed by using SEM.

Corner crack mechanism of boron-containing LCAK steel slabs

At Baoshan Iron ＆ Steel Co., Ltd., comer cracks of boron containing LCAK steel slabs had caused remarkable quality loss and mass flow disorder. With the help of fractography and thermodynamics analysis, the embrittlement mechanism of this steel grade was studied and the results are as follows： 1 The transformation from 3＇ to a starts at the austenite grain boundaries and a layer of thin ferrite film gradually forms around the austenite grains. Strain concentration will preferentially start inside the ferrite phase when the stress accumulates to a certain level. 2 The coarse BN particles acceleratedly precipitated at the γ/α interfaces further deteriorate the ductility of the ferrite film, and brittleness results in strain concentration and microvoid coalescence inside the ferrite film. Therefore the austenite grain boundaries are prone to intergranular failure. 3 The stoichiometry among Al, N and B is a very important factor influencing the hot ductility of this steel grade. By controling the B-to-N atomic ratio to above 1, all N can be fixed by B instead of A1. Thus coarsegrained steel is available and fewer grain boundaries and higher ductility can reduce the risk of comer cracks. （4） By adjusting the B-to-N atomic ratio,Baoshan Iron ＆ Steel Co.,Ltd. successfully reduced the number of cracks to nearly one tenth of that in the past and the hot tensile tests confirmed remarkable improvement in the hot ductility of this steel.

Kinetic Study of Curing Phenol-Formaldehyde/Tannin-Formaldehyde Composite Resins

This work presents a study on the uses of tannin-formadehyde derivative into phenolic resins. Eucalyptus tannins (T) were reacted with formaldehyde to form tannin-formaldehyde resin (TF). Then this derivative was used to prepare tannin-formaldehyde/phenol-formaldehyde resins (TFPF) at 20 and 40 %w/w. The kinetic values of thermal curing of Phenol-formaldehyde (PF), tannin-formaldehyde and tannin-formaldehyde/phenol-formaldehyde resins (TFPF) at 20 and 40 wt% from TF were studied by monitoring the weight changes which occurred in the samples weight during thermosetting process at four temperature (160°C, 180°C, 200°C and 220°C). The total evolved condensation products from curing reactions were about 32% - 36% per sample weight, and the rate of curing reaction constants was ranged between 0.163 %wt·min-1 at 160°C and 0.50 %wt·min-1 at 220°C. The path of TFPF curing and kinetic values indicated that these resins could be cured with the behavior and velocity comparable to that of PF. The activation energy of TFPF cross-linking was higher than that of PF. Increasing TF level to 20% and 40% into PF can reduce the amount of PF curing reactions density and weight loss percentage. The global kinetic properties showed that the TF participated in the thermoset network formation with acceptable activity and performance. The general results of this paper show that the TF is a suitable alternative material for partially replacement into PF resin.

Oxidation of Silicon and Boron in Boron Containing Molten Iron

A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that sili- con and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400℃. The favorable oxidation temperature of silicon was about 1 300-- 1 350℃. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.

Synthetic Process of Bio-Based Phenol Formaldehyde Adhesive Derived from Demethylated Wheat Straw Alkali Lignin and Its Curing Behavior

Lignin is a natural biopolymer with a complex three-dimensional network, commercially obtained from wasteliquid of paper pulp and bioethanol production, and could be a candidate for preparation of environment-friendlybio-based polyphenol material. In the present work, the demethylated wheat straw alkali lignin (D-Lig), preparedby demethylation of wheat straw alkali lignin (Lig) using an in-situ generated Lewis acid, was used to synthesizebio-based phenol formaldehyde resin adhesive (D-LPF) applied in plywood. Effects of synthetic process’s factors,including lignin substitution for phenol, NaOH concentration and molar ratio of formaldehyde to phenol, on thebonding strength and free formaldehyde content of D-LPF were investigated in detail, and the optimum syntheticprocess of D-LPF was obtained as following: Lignin substitution for phenol 60%, NaOH concentration 5.0% andmolar ratio of formaldehyde to phenol 2.0, and under the optimum reaction condition, the D-LPF presented lower free formaldehyde content (0.18%) and higher bonding strength (2.19 MPa), which was better than those ofcontaining-lignin phenol formaldehyde resin adhesive (LPF). Additionally, the curing behavior of the adhesivewas studied by differential scanning calorimetry (DSC) combined with gel time. It can be obtained that D-LPFresin adhesive had the shortest gel time, and fastest curing rate, compared with those of PF and L-PF resin adhesives. The curing kinetics data was fitted well by Kissinger model using non-isothermal DSC method, and theaverage activation energy value was 85.3 kJ/mol, slightly higher than that of commercial PF resin, while lowerthan that of LPF (90.2 kJ/mol). Finally, based on the analytical results of high temperature fourier transform infrared spectroscopy (FTIR), a possible curing mechanism of D-LPF was proposed.

Impregnated Paper-Based Decorative Laminates Prepared from Lignin-Substituted Phenolic Resins

High Pressure Laminates(HPL)panels consist of stacks of self-gluing paper sheets soaked with phenol-formaldehyde(PF)resins.An important requirement for such PFs is that they must rapidly penetrate and saturate the paper pores.Partially substituting phenol with bio-based phenolic chemicals like lignin changes the physico-chemical properties of the resin and affects its ability to penetrate the paper.In this study,PF formulations containing different proportions of lignosulfonate and kraft lignin were used to prepare paper-based laminates.The penetration of a Kraft paper sheet was characterized by a recently introduced,new device measuring the conductivity between both sides of the paper sheet after a drop of resin was placed on the surface and allowed to penetrate the sheet.The main target value measured was the time required for a specific resin to completely penetrate the defined paper sample(“penetration time”).This penetration time generally depends on the molecular weight distribution,the flow behavior and the polarity of the resin which in turn are dependent on the manufacturing conditions of the resin.In the present study,the influences of the three process factors:(1)type of lignin material used for substitution,(2)lignin modification by phenolation and(3)degree of phenol substitution on the penetration times of various lignin-phenolic hybrid impregnation resins were studied using a complete twolevel three-factorial experimental design.Thin laminates made with the resins diluted in methanol were mechanically tested in terms of tensile and flexural strains,and their cross-sections were studied by light microscopy.

Boron-containing Phthalonitrile Resin:Synthesis,Curing Behavior,and Thermal Properties

A novel boron-containing monomer,(4-(3,4-dicyanophenoxy)phenyl)boronic acid(BPhPN)was synthesized and used to promote the curing process of phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy)benzene(MPN).Differential scanning calorimetry and rheological analysis were used to study the curing behaviors of BPhPN/MPN(namely B-MPN),and results suggested that B-MPN systems have better processibility.FTIR spectra and solid-state 13C-NMR exhibited triazine and isoindoline have been formed in the curing process.Boron-containing Lewis acid curing mechanism was preliminarily speculated and verified by two model compounds with different boron chemical environments.The thermogravimetric analysis and dynamic mechanical analysis demonstrated that the cured B-MPN polymers showed excellent thermal stability and heat resistance,which were comparable with conventional catalytic systems for phthalonitrile resins.This study not only presented a novel curing system for phthalonitrile resins,but also shed light on future design of high temperature thermosets.

NaOH and Ba(OH)_2 Compound Catalyzed PhenolResorcinol-Formaldehyde Copolycondensation Resin Adhesive for Recombined Bamboo

In order to reduce the curing temperature, shorten the curing time of phenol-formaldehyde(PF) resin adhesive, and ensure the good water-solubility, NaOH and Ba(OH)_2 were used as compound catalysts. The influences of the adding time of Ba(OH)_2, the adding amount of NaOH, Ba(OH)_2 and resorcinol on the properties of adhesives were studied. The properties of NaOH catalyzed phenol-formaldehyde(PF) adhesive, NaOH and Ba(OH)_2 compound catalyzed PF adhesive, NaOH and Ba(OH)_2 compound catalyzed phenol-resorcinol-formaldehyde(PRF) adhesive, and the prepared recombinant bamboo with three kinds of adhesives were compared. The experimental results show that NaOH and Ba(OH)_2 compound catalyst not only shortens the curing time of PF adhesive, but also guarantees the suitable water solubility of adhesive. After copolycondensation with resorcinol, the curing time of adhesive is further shortened, the water solubility is improved obviously, and the highest bonding strength is obtained. Infrared spectrum analysis shows that the reaction activity point of NaOH and Ba(OH)_2 compound catalyzed PRF adhesive will increase, so that both the curing temperature and curing enthalpy decrease.

LARIX GMELINI TANNIN-BASED ADHESIVE FOR PLYWOOD

Larix tannin-phenol-formaldehyde (TPF) adhesive, having 60% by weight of phenol bcing replaced, was evaluated for its utilization in plywood. The kinetic characteristic of the TPF resin was investigated through differential scanning calorimetry (DSC) and the results obtained from the DSC scans show that the resin has a little bit different thermochemical behavior from that of phenol-formaldehyde (PF) resin. Two kinds of plywood panels wcre produced using the TPF adhesive in laboratory. The desired test results met the Chinese GB 9846-88 and ZB B70006-88, respectively, and the long assembly time of TPF resin in preparing plywood can be improved by mixing with the filler.All the properties of plywoods bonded with the TPF adhesive were compared with those obtaincd with synthetic PF adhesive.

Scope of translational medicine in developing boroncontaining compounds for therapeutics

The ubiquitousness of naturally occurring boron-containing compounds(BCCs) has led to their constant contact with humankind.Recently,many synthetic BCCs have been elaborated for a broad spectrum of purposes,especially boric,boronic and borinic acids.Although BCCs were once employed primarily as antiseptics and later as antibiotics,they have become an increasingly relevant therapeutic tool.Nevertheless,this potential of BCCs has been drastically limited due to some unfortunate intra-hospital accidents in the 1940 s and 1950 s.The increasing use of BCCs as insecticides,antimicrobials,and other agents is providing new insights into their role in the physiology of several living species and in the pathophysiology of humans.It is becoming clear that BCCs act through a wide range of mechanisms,as do their corresponding boron-free counterparts.When comparing BCCs and similar boron-free compounds,in many cases the former show advantages in the medical field.The current minireview focuses on how BCCs have been developed by means of translational medicine,a process connecting biomedical research with clinical applications.This process of discovery is currently in an exponential stage.

Ultrafine microstructure in microalloyed steel by a new thermomechnical process

Low carbon microalloyed steel containing 0.062 percent C, 2.34 percent Mn,0.044 percent Nb, 0.029 percent Ti, 0.032 percent V in mass fraction and small amount of B wasprepared in laboratory. Slabs of the steel were rolled into plates of 6mm in thickness followed byaccelerated cooling. The plates possess very high yield strength and reasonable ductility, and theyield ratio is about 0.8. Ultra-fine ferrite structure with micrometer dimension was observed in thesurface layer of the plates. Moreover, the effect of the finishing rolling temperature on the finalmicrostructure and formation mechanism of ultra-fine ferrite as well as the gamma->alphatransformation behavior of the steel was discussed.

Incorporation of carbazole and boron-containing dye into conjugated microporous polymers with significant aerobic oxidative photocatalysis

Carbazole-based conjugated microporous polymers(CMPs)as a new type of advanced porous material have created tremendous research curiosities in the area of photocatalysis.Besides,introducing boron-containing dyes into the CMPs framework was rare but will be rather promising due to their unique properties,including strong electron-accepting capability,efficient catalytic behaviour,significant absorption coefficient and high quantum.Herein,we rationally designed and prepared two new CMPs,i.e.Cz-BF_(2)-CMP and Cz-BPh2-CMP with the combination of carbazole and boron-containing dye as electron donor and acceptor motifs,respectively.Due to the efficient D-A effect between carbazole and boron-dye which not only accelerated the interfacial charge transfer efficiency but also improved the separation capability of photogenerated electron-hole pairs,both CMPs exhibited excellent photocatalytic performances in organic transformations such as green synthesis of benzimidazole in aqueous solution and aerobic oxidation of thioether in EtOH.

Study on Physical and Mechanical Properties of Poplar Modified by Phenol-formaldehyde Resin

Impregnation method can effectively improve physical and mechanical properties of wood. In this study, plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30% under vacuum-pressure process, and then dried and machined according to the related standards. The results show that the physical and mechanical properties of poplar can be improved by the treatment, except for toughness. The average density of poplar increases from 0.397 to 0.710 g/cm3, the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%, 112.97% and 87.69%, respectively, compared to the untreated. And the hardness values on radial and tangential sections, and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%, 82.78%, 71.43% and 22.06%, respectively; while toughness decreases by 48.80%.

Optimization of boron-containing acceptors towards high-efficiency TADF emitters:sky-blue OLEDs with external quantum efficiency of 32.6%

Two new thermally activated delayed fluorescence(TADF)molecules,13-(2,12-di-tert-butyl-5,9-dioxa-13bboranaphtho[3,2,1-de]anthracen-7-yl)-5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine(BOBT)and 13-(4-(dimesitylboranyl)-3,5-dimethylphenyl)-5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine(BPBT),are constructed via connecting the 5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine(BTDMAC)donor(D)with triarylboron or oxygen-bridged cyclized boron acceptors(A),respectively.In comparison with the photoluminescence quantum yield(PLQY)of 84%for BPBT,BOBT shows a higher PLQY of 100%,due to the multi-resonance effect of the boron-oxygen skeleton.In addition,the D-A-type molecular structural characteristic endows the boron-containing BOBT emitter with a fast reverse intersystem crossing rate on the order of 106 s^(-1).The sky-blue organic light-emitting diode(OLED)employing the BOBT emitter achieves state-of-the-art device performances with a high external quantum efficiency of 32.6%.

Research Progress of Metal-Based Shielding Materials for Neutron and Gamma Rays

The radiation generated by nuclear reaction is harmful to human body and equipment,thus the radiation shielding materials that employ the shielding ability from neutron and gamma rays are the best candidates according to application situations and radiation sources.In this paper,the researches of metal-based neutron and gamma rays or multiple purpose shielding materials are systematically summarized,and the respective and principal problems of these materials with respect to shielding effectiveness and other performances,such as corrosion,mechanical properties,manufacture,etc.,are discussed.Finally,the prospect of shielding materials is outlined,which suggests that the development of highly efficient and multiply functional radiation shielding materials with good environmental compatibility is one of the future development trends.

Recent developments in the medicinal chemistry of single boron atom-containing compounds

Various boron-containing drugs have been approved for clinical use over the past two decades,and more are currently in clinical trials.The increasing interest in boron-containing compounds is due to their unique binding properties to biological targets;for example,boron substitution can be used to modulate biological activity,pharmacokinetic properties,and drug resistance.In this perspective,we aim to comprehensively review the current status of boron compounds in drug discovery,focusing especially on progress from 2015 to December 2020.We classify these compounds into groups showing anticancer,antibacterial,antiviral,antiparasitic and other activities,and discuss the biological targets associated with each activity,as well as potential future developments.