Synthesis of nanoscale zero-valent iron supported on exfoliated graphite for removal of nitrate

Nano ZVI particles supported on micro-scale exfoliated graphite were prepared by using KBH4 as reducing agent in the H2O/ethanol system. The supported ZVI materials generally have higher activity and greater flexibility for environmental remediation applications. The exfoliated graphite as the support was treated beforehand to hydrophilic material. Nano iron particles are deposited onto the rough graphite surface while those were formed by borohydride reduction. The possible nitrate reduction pathways were proposed. The TEM image shows that iron particles are highly dispersed on the surface of graphite and several of iron particles are imbedded in the pit of support surface. In this synthesis, iron particles have a nearly spherical shape with a grain size of 50?100 nm. The surface areas of materials with different iron loadings of 3.5%, 7.0%, 10.0%, 15.0% and 20.0%(mass fraction) are 2.89, 9.55, 8.45, 23.8 and 6.18 m2·g?1 by BET surface analyzer. The chemical reduction of nitrate by supported nano ZVI in aqueous solution were tested in series batch experiments. Experiment results suggest that NO3? can be more rapidly reduced to NH4+ at neutral pH and anaerobic conditions by supported nano ZVI than unsupported nano ZVI or ZVI scraps. The 15% nano Fe/graphite shows the best reduction efficiency contrasted with other Fe loading particles.

Evaluating the Effectiveness of Air Pollution Abatement Policy of Hong Kong

As only about 15% of the total time of people in Hong Kong was spent outdoors, it would be more valuable if the associated effectiveness and impact of the recently proposed abatement measures could be expressed in terms of the improvement in the total exposure levels. This paper uses an exposure assessment model developed from the local microenvironment concentration data together with our surveyed time activity patterns to evaluate the effectiveness of the proposed air pollution abatement policy. Prior to the enforcement of abatement measures, about 2.5% of the young group and 1.2% of the adult group having their exposure levels exceeded that defined by the current 8-hour PM10 standard (180 μg/m3). With the enforcement of abatement measures, only 0.3% of the adult group would be restored to a safe level.

Headedness in Yorǘhbá： An Examination of the Deviant Value of Determiner Phrase

The issue of ＂headedness＂ is a product of Chomsky＇s （1988） notion of UG （Universal Grammar） that led to the development of a framework known as P＆P （Principles and Parameters） theory. It is this theory we have adopted for our analysis in this paper. The purpose of this paper is to examine the inconsistency in the value of Head Parameter with reference to the value of DP （determiner phrase） in Yorfib^i. As a native speaker of Yorfib~, the author has adopted an introspective method of data collection and used the intuitive knowledge of other native speakers of the language for necessary clarifications. Despite the fact that English and Yorfib~ are both head-initial, the structure of the NPs （noun phrases） in English shows that the head noun is always pre-modified, making the NP ＂head-final＂--a violation of the value of Head Parameter in the language. This necessitated the need for Abney＇s （1987） DP hypothesis; in which the determiner heads its own phrase, thereby making a NP in English head-initial. This solves the problem of Head Parameter in English. However, since nouns in Yor/lb^i are post-modified, adopting ＂DP-analysis＂ will automatically produce head-final--a violation of the value of Head Parameter in the language. Given the inconsistency in the specification of head-complement order among the noun phrases in English and Yorfib~, this paper proposes to set a parameter for SVO （Subject-Verb-Object） languages with pre-modification （like English） to adopt ＂DP-analysis＂, and those with post-modification （like Yorfib^t） to adopt ＂NP-analysis＂. This will ensure ＂head-initial＂ value for the two categories of SVO languages

Evaluating the influence of 6 MV and 15 MV photon beams on prostate intensity-modulated radiation therapy plans

Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer. Methods Thirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. Al plans were generated by using suitable planning objectives and dose con-straints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy. Results The mean percentage values of V70 Gy for the rectal wal for the plans with 6 MV, 15 MV, and mixed-energy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40 Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-en-ergy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.Conclusion These preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinical y relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overal higher plan quality for deep-seated tumors.

原子核形变与价核子数的系统关系

利用NpNn 方法研究了A≥ 10 0的偶 -偶核基态四极形变参数 β的系统规律 .根据质量数以及价质子 (中子 )是粒子还是空穴对原子核分组 ,发现 β与 (NpNn) 1 2 的关系曲线是平滑的 .不同组中原子核的 β变化曲线的斜率和趋势显示 ,价核子和空穴对核四极形变的贡献不同 .通过对近滴线原子核理论形变值的变化规律的研究表明 ,在NpNn 方法中p n价核子相互作用的一般关系可能依然适用于不稳定核 .

Assessment of Potential Nutrient Release from Phosphate Rock and Dolostone for Application in Acid Soils

Finding alternative local sources of plant nutrients is a practical, low-cost, and long-term strategy. In this study, laboratory column experiments were conducted in a completely randomized design to evaluate the feasibility of using phosphate rock and dolostone as fertilizers or acid-neutralizing agents for application in tropical acid soils. The dissolution rates of different particle-size fractions(0.063–0.25, 0.25–0.5, and 0.5–2 mm) of both rocks were studied by citric acid solution at p H 4 and 2 and water, with extraction times of 1, 3, 5, 7, 12, 24, 72, 144, 240, and 360 h. The results showed that the dissolution of both rocks depended on the particle size,leaching solution, and extraction time. The dissolution rate of rock-forming minerals increased as the specific surface area increased,corresponding to a decrease in particle size. In all cases, the release kinetics was characterized by two phases: 1) a first stage of rapid release that lasted 24 h and would ensure short-term nutrient release, and 2) a second stage of slow release after 24 h, representing the long-term nutrient release efficiency. Both rocks were suitable as slow-release fertilizers in strongly acid soils and would ensure the replenishment of P, Ca, and Mg. A combination of fine and medium particle-size fractions should be used to ensure high nutrient-release efficiency. Much work could remain to determine the overall impact of considerable amounts of fresh rocks in soils.

Evaluation of Particle Numbers via Two Root Mean Square Radii in a 2-Species Bose–Einstein Condensate

The coupled Gross–Pitaevskii equations for two-species BEC have been solved analytically under the Thomas-Fermi approximation(TFA). Based on the analytical solution, two formulae are derived to relate the particle numbers N_A and N_B with the root mean square radii of the two kinds of atoms. Only the case that both kinds of atoms have nonzero distribution at the center of an isotropic trap is considered. In this case the TFA has been found to work nicely. Thus, the two formulae are applicable and are useful for the evaluation of N_A and N_B.

Evaluation of the effective thermal conductivity of composite polymers by considering the filler size distribution law

We present an empirical model for the effective thermal conductivity (ETC) of a polymer composite that includes dependency on the filler size distribution-chosen as the Rosin-Rammler distribution. The ETC is determined based on certain hypotheses that connect the behavior of a real composite material A, to that of a model composite material B, filled with mono-dimensional filler. The application of these hypotheses to the Maxwell model for ETC is presented. The validation of the new model and its characteristic equation was carried out using experimental data from the reference. The comparison showed that by using the size distribution law a very good fit between the equation of the new model (the size distribution model for the ETC) and the reference experimental results is obtained, even for high volume fractions, up to about 50%.

A covalent organic framework-based multifunctional therapeutic platform for enhanced photodynamic therapy via catalytic cascade reactions

Utilizing the unique tumor microenvironment(TME)to conduct chemical reactions for cancer treatment becomes a hot topic recently.Nevertheless,single chemical reaction in TME is often restricted by scanty reaction substrates and slow reaction rate.Meanwhile,the toxic substances produced by the reactions are usually not enough to kill cancer cells.Herein,using covalent organic frameworks(COFs)as the template,Au nanoparticles(Au NPs)were subsequently grown on the surface of the COF,then a thin layer of manganese dioxide(MnO2)was coated over the material,and finally hyaluronic acid(HA)was introduced to improve the biocompatibility.The resultant product,named COF-Au-MnO2,was involved in several processes to form cascade reactions in the TME.Specifically,under hypoxic conditions,COF-Au-MnO2 could react with intratumoral H2O2 to produce O2 to enhance the type II photodynamic therapy(PDT),and Au NPs could decompose glucose to promote starving-like therapy.Besides,starving-like therapy can also produce H2O2 to increase O2 production.Simultaneously,MnO2 can consume glutathione(GSH)to enhance the antitumor efficacy,and the released Mn2+could be used for T1-weighted magnetic resonance imaging(MRI).Both in vitro and in vivo experiments had proven excellent cancer cell killing effect and antitumor efficacy of COF-Au-MnO2via such a cycle-like process.

Performance evaluation of anti-radiation based on the gamma degradation process

In the environment of space radiation, the high-energy charged particles or high-energy photons acting on a spacecraft can cause either temporary device degradation or permanent failure. The traditional probability model is difficult to obtain reliable estimation of unit radiation resistance performance with small samples. Considering that different products will change differently after high-energy particle radiation, we construct a model based on the gamma degradation process. This model can efficiently describe the law of unit radiation resistance variation with the total radiation dose levels under the effect of the total dose and displacement damage. Finally, the proposed model is used to assess the anti-radiation performance of the N-channel power MOSFET device STRH60N20FSY3 produced by STM to obtain average unit radiation resistance, survival probability, survival function, etc.