Dechlorination mechanism of 2,4-dichlorophenol by Ni/Fe nanoparticles in the presence of humic acid

To understand the feasibility of its application to the in situ remediation of contaminated groundwater, the dechlorination of 2,4-dichlorophenol （2,4-DCP） by Ni/Fe nanoparticles in the presence of humic acid （HA） was investigated. We found that, as high performance liquid chromatography （HPLC） was used, the 2,4-DCP was first quickly reduced to o-chlorophenol （o-CP） andp-chlorophenol （p-CP）, and then reduced to phenol as the final product. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Ni/Fe nanoparticles, as the HA concentration increased, the removal rate decreased evidently. It also demonstrated that 2,4-DCP was reduced more easily to o-CP than to p-CP, and that the sequence of the tendency in dechlorination of intermediates was p-CP〉o-CP. Transmission electron microscope （TEM） showed that HA could act as an adsorbate to compete reactive sites on the surface of Ni/Fe nanoparticles to decrease the dechlorination rate. Also we concluded that the dechlorination reaction of 2,4-DCP over Ni/Fe nanoparticles progressed through catalytic reductive dechlorination.     

Science Letters:Dechlorination mechanism of 2,4-dichlorophenol by Ni/Fe nanoparticles in the presence of humic acid

To understand the feasibility of its application to the in situ remediation of contaminated groundwater, the dechlori-nation of 2,4-dichlorophenol (2,4-DCP) by Ni/Fe nanoparticles in the presence of humic acid (HA) was investigated. We found that, as high performance liquid chromatography (HPLC) was used, the 2,4-DCP was first quickly reduced to o-chlorophenol (o-CP) andp-chlorophenol (p-CP), and then reduced to phenol as the final product. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Ni/Fe nanoparticles, as the HA concentration increased, the removal rate decreased evidently. It also demonstrated that 2,4-DCP was reduced more easily to o-CP than to p-CP, and that the sequence of the tendency in dechlorination of intermediates was p-CP>o-CP. Transmission electron microscope (TEM) showed that HA could act as an adsorbate to compete reactive sites on the surface of Ni/Fe nanoparticles to decrease the dechlorination rate. Also we con-cluded that the dechlorination reaction of 2,4-DCP over Ni/Fe nanoparticles progressed through catalytic reductive dechlorination.     

Kinetics of 2,4-dichlorophenol dechlorination by Pd-Fe bimetallic nanoparticles in the presence of humic acid

The remediation of groundwater which contains chlorinated organic compounds （COCs） by nanoscale bimetallic catalysts has received increasing interest in recent years. This report presents the dechlorination of 2,4-dichlorophenol （2,4-DCP） by Pd-Fe bimetallic nanoparticles in the presence of humic acid （HA） to investigate the feasibility of using Pd-Fe for the in situ remediation of contaminated groundwater. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Pd-Fe nanoparticles. The rate constant k values of 2,4-DCP dechlorination were 0.017, 0.013, 0.009, 0.006 and 0.004 min^-1 for HA concentrations of 0, 5, 10, 15 and 20 mg/L, respectively. The relationship between HA dosage and k values can be described as a linear model.     

水中2,4-二氯苯酚和五氯苯酚电子束辐射降解的研究

用电子束辐射降解水中的2, 4-二氯苯酚(2, 4-DCP)和五氯苯酚(PCP), 研究辐照剂量对溶液初始质量浓度各为50 mg/L的2种氯代苯酚辐射降解和去除有机氯的影响. 同时研究了溶液不同的初始质量浓度、pH值和去氧状态等条件对辐射降解的影响. HPLC的测试结果表明: 随着辐照剂量的增加,氯代苯酚的降解率增加, 溶液中的氯离子增加, 但辐照后溶液中仍有2, 4-DCP和PCP的残余物. 试验结果表明: 有机氯辐射降解的速度要比无机氯生成的速度快得多; 溶液的去氧也能加快氯代苯酚的降解; 在酸性到中性条件下比碱性条件下更利于有机氯裂解.     

2,4-二氯酚表面磁性分子印迹聚合微球合成及其吸附特性研究

采用表面印迹技术制备了磁性分子印迹聚合物（Fe3O4@SiO2@MIPs）,使用扫描电镜（SEM）、透射电镜（TEM）和红外光谱（FT-IR）对产物的结构进行了表征。通过吸附性能实验研究证实了制备的Fe3O4@SiO2@MIPs对目标分子2,4-二氯酚（2,4-DCP）具有快速的吸附动力学特征和较高的吸附容量;与非印迹聚合物（Fe3O4@SiO2@NIPs）比较,Fe3O4@SiO2@MIPs对2,4-DCP表现出显著的亲和性;吸附选择性实验表明,Fe3O4@SiO2@MIPs对2,4-DCP具有较强的特异结合性能。此外,5次的重复使用后,制备材料的吸附效率仍可达80%以上,说明该材料具有可重复使用性。     

Study of transport behavior for Fe-doping La<Subscript>0.67</Subscript>Ca<Subscript>0.33</Subscript>MnO<Subscript>3</Subscript> perovskite manganese

Systematic studies of the transport properties of La_0.67Ca_0.33Mn_1?xFe _x O₃ (x=0–0.3) systems showed that with increasing Fe-doping contentx the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition temperature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe³⁺ doping, which easily forms Fe³⁺?O^2??Mn⁴⁺ channel, suppressing the double exchange Mn³⁺?O^2??Mn⁴⁺ channel and enhancing the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions.     

Inquiring scaffolds in laboratory tasks: an instance of a “worked laboratory guide effect”?

The study explores if established support devices for paper–pencil problem solving, namely worked examples and incremental scaffolds, are applicable to laboratory tasks. N?=?173 grade eight students solved in dyads a physics laboratory task in one of three conditions. In condition A (unguided problem solving), students were asked to determine the mass of an unknown object by applying Hooke’s law. In condition B (laboratory guide), students received a guide which instructed and explained each solution step. In condition C (incremental scaffolds), the solution steps were presented incrementally on learner demand and were preceded by strategic prompts. Dependent variables were learning outcomes (solution, retention, knowledge) and motivational learning experiences (basic needs, situational interest, deeper level processing). The laboratory guide (B) led to better learning outcomes (d?=?0.42) but lower motivation (d?>?0.38) compared to unguided problem solving (A). Incremental scaffolds (C) led to higher motivation (d?>?0.44) but similar learning outcomes compared to a laboratory guide.     

Effect of static magnetic field on α-amylase activity and enzymatic reaction

The effect of magnetic field on α-amylase was studied. Under the experimental conditions, α-amylase solution was treated by 0.15 T, 0.30 T and 0.45 T static magnetic fields for a known period of time, then the activity, kinetic parameters, and the secondary conformation were investigated. The results showed that there was a considerable effect of the magnetic exposure on the α-amylase. The activity was increased by 27%, 34.1%, 37.8% compared with the control. It was also found that both kinetic parameters K _m and V _m could be decreased due to the increasing magnetic field, K _m decreased from 2.20×10^?2 to 0.87×10^?2, whereas V _m decreased from 2.0×10^?3 g/min to 1.1×10^?3 g/min. At the same time, there were some irregular changes in α-amylase secondary conformation.     

Two-order Hermite vector-interpolating subdivision schemes

INTRODUCTION Along with the great progress in 3D data meas- urement device and the popularization of complex solid modelling, recursive subdivision has been a research focus in CAGD and CG (Wang et al., 2001). However, most interpolating subdivision schemes are Lagrange-type schemes whose smoothness is not easily verified. The geometric features of this kind of subdivided curves and surfaces are difficult to be generated, which restricts the application of subdivi- sion methods. From a…     

Characterization of the mean velocity of a circular jet in a bounded basin

A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×10⁴. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio.     

Adsorption of 2,4-Dichlorophenol from Aqueous Solution onto Microwave Modified Activated Carbon： Kinetics and Equilibrium

Batch experiments were conducted to investigate the adsorption of 2,4-dichlorophenol (2,4-DCP) onto microwave modified activated carbon (AC) at three different temperatures (303 K, 313 K and 323 K). Adsorption isotherms, kinetics, and thermodynamics of the adsorption process were explored. Equilibrium data were fitted into Langmuir and Freundlich equations, and the result reveals that the Freundlich isotherm model fits better than the Langmuir model. Three simplified kinetic models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations were adopted to examine the mechanism of the adsorption process, and the pseudo-second-order kinetic model proved to be the best in describing the adsorption data. The thermodynamic parameters of the adsorption process were estimated, showing that the adsorption of 2,4-DCP was exothermic and spontaneous, and the adsorption studied in this paper can be assigned to a physisorption mechanism.     

Electrochemical study on semiconductive properties of the passive film on rebar in concrete

INTRODUCTION Steel rebar embedded in concrete is protectedagainst corrosion by the thin passive film on its sur-face and the physical protection from concrete. Thealkaline environment (pH≥12.5) of the concrete poresolution triggers passivation on the rebar surface andformation of the protective oxide film. The physicaprotection of concrete coverage hinders the invasionof aggressive agents. However, this passivity can bebroken down by local pH loss as a result of concretecracking or the…     

Apigenin-7-<Emphasis Type="Italic">O</Emphasis>-β-<Emphasis Type="SmallCaps">d</Emphasis>-glycoside isolation from the highly copper-tolerant plant <Emphasis Type="Italic">Elsholtzia splendens</Emphasis>

Elsholtzia splendens (Lamiaceae) is a copper-tolerant plant species growing on copper deposits in the south of China. Chromatographic separation of n-BuOH extracts from the flowering aerial biomass afforded apigenin-7-O-β-d-glycoside, using macroporous resin, Sephadex? LH-20 gel, polyamide resin as well as preparative high-performance liquid chromatography (P-HPLC) columns. Chemical structure was elucidated using HPLC/ESI-MS (electrospray ionization-mass spectrometry), Fourier transform infrared (FTIR), and ¹D- and ²D-nuclear magnetic resonance (NMR). Apigenin-7-O-β-d-glycoside could be the post-harvesting product from E. splendens biomass.     

Effects of levobupivacaine and bupivacaine on rat myometrium

Objective： To study the effect of levobupivacaine and bupivacaine on the contractility of isolated uterine muscle strips from pregnant and non-pregnant female rats. Methods： Full-thick myometrial strips were prepared from 18- to 2 l-day pregnant （n=8） and non-pregnant rats （n=7）. After contractions became regular, strips were exposed to cumulative concentrations of the two drugs from 10^-8 to 10^-4 mol/L, amplitude and frequency of the uterine contraction was recorded. Results： Two local anesthetics caused a concentration dependent inhibition on contractility of myometrial strips from pregnant and non-pregnant rats. In the myometrium from non-pregnant rats, -log/C50 of levobupivacaine and bupivacaine were 4.85 and 4.25 respectively. In the myometrium from pregnant rats, similar concentrations of levobupivacaine and bupivacaine were observed, -log/C50 were 2.7 and 2.9 respectively. Levobupivacaine produced an increase in amplitude of contractions, while bupivacaine showed an increased trend in frequency. Conclusion： These results demonstrate that levobupivacaine and bupivacaine may inhibit myometrium contractility. The inhibitory effect of levobupivacaine or bupivacaine is not enhanced by gestation in rat. Levobupivacaine may have more positive influence than bupivacaine in pregnant myometrium.     

Uptake,transport and distribution of molybdenum in two oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis> L.) cultivars under different nitrate/ammonium ratios

Objectives

To investigate the effects of different nitrate sources on the uptake, transport, and distribution of molybdenum (Mo) between two oilseed rape (Brassica napus L.) cultivars, L0917 and ZS11.

Methods

A hydroponic culture experiment was conducted with four nitrate/ammonium (NO₃ ^?:NH₄ ⁺) ratios (14:1, 9:6, 7.5:7.5, and 1:14) at a constant nitrogen concentration of 15 mmol/L. We examined Mo concentrations in roots, shoots, xylem and phloem sap, and subcellular fractions of leaves to contrast Mo uptake, transport, and subcellular distribution between ZS11 and L0917.

Results

Both the cultivars showed maximum biomass and Mo accumulation at the 7.5:7.5 ratio of NO₃ ^?:NH₄ ⁺ while those were decreased by the 14:1 and 1:14 treatments. However, the percentages of root Mo (14.8% and 15.0% for L0917 and ZS11, respectively) were low under the 7.5:7.5 treatment, suggesting that the equal NO₃ ^?:NH₄ ⁺ ratio promoted Mo transportation from root to shoot. The xylem sap Mo concentration and phloem sap Mo accumulation of L0917 were lower than those of ZS11 under the 1:14 treatment, which suggests that higher NO₃ ^?:NH₄ ⁺ ratio was more beneficial for L0917. On the contrary, a lower NO₃ ^?:NH₄ ⁺ ratio was more beneficial for ZS11 to transport and remobilize Mo. Furthermore, the Mo concentrations of both the cultivars’ leaf organelles were increased but the Mo accumulations of the cell wall and soluble fraction were reduced significantly under the 14:1 treatment, meaning that more Mo was accumulated in organelles under the highest NO₃ ^?:NH₄ ⁺ ratio.

Conclusions

This investigation demonstrated that the capacities of Mo absorption, transportation and subcellular distribution play an important role in genotype-dependent differences in Mo accumulation under low or high NO₃ ^?:NH₄ ⁺ ratio conditions.

     

Evaluation of efficacy of resin hemoperfusion in patients with acute 2,4-dinitrophenol poisoning by dynamic monitoring of plasma toxin concentration

Objective: The intoxications caused by 2,4-dinitrophenol (2,4-DNP), even death, have been frequently reported in recent years. This study aims to investigate the dynamic changes of plasma toxin concentration and explore the clinical value of resin hemoperfusion (HP) in the treatment of patients with acute 2,4-DNP poisoning. Methods: We reported 16 cases of acute 2,4-DNP poisoning through occupational exposure due to ignoring the risk of poisoning. The blood samples were collected from the 14 survivors. According to the different treatments of resin HP, the survivors were divided into routine HP (n=5) and intensive HP (n=9) groups. Ultra high performance liquid chromatography/tandem mass spectroscopy (UPLC-MS/MS) was used to detect the 2,4-DNP concentration in plasma in this study. Results: The 14 survivors recovered very well after treatment. The initial plasma 2,4-DNP concentrations (C ₁) of survivors ranged from 0.25 to 41.88 µg/ml (mean (12.56±13.93) µg/ml). A positive correlation existed between initial plasma 2,4-DNP concentration (C ₁) and temperature. The elimination of 2,4-DNP was slow and persistent, and the total clearance rates of plasma toxin from the 1st to 3rd day (R ₃), the 3rd to 7th day (R _3–7), and the 1st to 7th day (R ₇), were only (53.03±14.04)%, (55.25±10.50)%, and (78.29±10.22)%, respectively. The plasma toxin was cleared up to 25 d after poisoning in most of the patients. The R ₃, R _3–7, and R ₇ in the intensive HP group were all apparently higher than those in the routine HP group, with statistical significance (P<0.05). Simultaneously, the elimination half-life (t _1/2) of 2,4-DNP in the intensive HP group was apparently shorter than that in the routine HP group, with statistical significance (P<0.05). Conclusions: The clinicians should be aware of this slow and persistent process in the elimination of plasma 2,4-DNP. Higher initial plasma toxin concentration resulted in a more severe fever for the patient. According to the limited data, longer and more frequent resin HP may accelerate to eliminate the poison.     

Synthesis and characterization of degraded gelatin grafted poly(ɛ-caprolactone) copolymers

Hydrophilic degraded gelatin was modified with hydrophobic poly(ε-caprolactone) (PCL) via a chemical grafting route.Firstly,PCL with one hydroxyl end group was prepared by the ring-opening polymerization of εcaprolactone (ε-CL) with tin (Ⅱ) 2-ethylhexanoate as catalyst and n-butyl alcohol as initiator.Secondly,the PCL reacted with isophorone diisocyanate (IPDI) to prepare PCL with isocyanate functional group (PCL-NCO).Hydroxylamine was used to degrade gelatin by the cleavage between asparagine and glycine residues of gelatin.PCL-NCO reacted with the hydroxyl/amino groups of degraded gelatin in a homogeneous system and yielded the PCL modified gelatin copolymers.The gelatin grafted PCL copolymers were measured by means of XRD,FTIR,DSC and 1 H NMR.The results confirmed the conjugation of PCL onto gelatin chains.The PCL modified gelatin can be used as biomaterials owing to their biocompatibility and biodegradation.     

Results on energies for trees with a given diameter having perfect matching

Let Γd2nbe the set of trees with a given diameter d having a perfect matching,where 2n is the number of vertex.For a tree T in Γd2n,let Pd+1be a diameter of T and q = d m,where m is the number of the edges of perfect matching inPd+1.It can be found that the trees with minimal energy in Γd2nfor four cases q = d 2,d 3,d 4,[d2],and two remarks aregiven about the trees with minimal energy in Γd2nfor2d 33q d 5 and [d2] + 1 q2d 33 1.     

Counting forumula for 3 × 3 generalized magic squares

The aim of this article is to explicitly compute the number of generalized magic squares of order 3. Counting functions for (generalized) magic squares of order n with fixed line sum r is known to be a polynomial function in r over ? of degree (n?1)². For higher values of n, it is quite difficult to explicitly write down such counting functions.     

Kinetics of the reaction between boron trifluoride methanol complex and sodium methoxide to produce enriched <Superscript>10</Superscript>B methylborate

The relation of boron trifluoride concentration with conductivity in boron trifluoride methanol solution (BF₃-CH₃OH)was power exponent fitted in low concentration range. The kinetics of the reaction between boron trifluoride methanol complex and sodium methoxide to produce enriched ¹⁰B methylborate was proposed based on a detailed mechanism study, and was verified by acid-base titration method and conductivity method. It was found that this reaction is first order reaction and the rate constant is 0.022 min^?1 at 338 K(65 °C), the activity energy is 65 kJ/mol. In addition, it was found that the conductivity method is more feasible to measure the kinetic curve than acid-base titration method.