The art and science of handheld instrument maintenance

Calling maintenance of handheld water quality instrumentation an “art and science” might seem to be a misnomer, but it is not. A little common sense and some knowledge of science go a long way in helping you to avoid becoming a victim of your instrumentation. When in doubt, slow down and follow the procedures and you'll find that they really do work.     

基于Mold Wizard的注塑模自动设计

通过电脑机箱塑胶面板模具的自动设计，介绍Mold Wizard设计向导的使用方法和注意事项，使设计人员能在循序渐进的引导之下，高质、高效地完成模具设计任务。     

Biosorption behaviors of Cu, Zn, Cd and mixture by waste activated sludge

Biosorption of heavy metal ions, such as Cu²⁺, Cd²⁺ and Zn²⁺, was carried out using waste activated sludge from municipal sewage treatment plant as adsorption material, and the effects of parameters, such as pH value, temperature, reaction time and sorption duration, were studied in detail. The results indicate that the removal rates of Cu²⁺, Zn²⁺ and Cd²⁺ with low concentration are 96.47%, 80% and 90%, respectively, adsorbed by waste activated sludge. Little effect of dosage of activated sludge on the adsorption of Cu²⁺ and more effects on the adsorption of Zn²⁺ and Cd²⁺ are observed. Little effect of temperature is observed, while pH value and adsorption time exert important influence on the sorption process. The adsorption behaviors of heavy metal ions all have parabolic relationships with pH value. The optimum pH value is between 6 and 10, and the optimum adsorption time is 1 h. In single heavy metal ion system, the sorption processes of Cu²⁺, Zn²⁺ and Cd²⁺ are in accordance with Freundlich model, which indicates that it is suitable for the treatment of these three heavy metal ions using intermittent operation. In addition, the sorption capacity of the sludge for Cu²⁺ is preferential to the other two ions.     

谈谈建筑中的有关文化

指出在人类社会的发展进程中 ,建筑与文化是密不可分的。建筑以其独有的艺术形式 ,表现了人类文化在各个历史阶段的水平 ,以及对未来的理想、追求和向往。可以说 ,建筑已成为人类文明的一个重要组成部分。因此 ,广大建筑师们 ,一定要从文化入手来探讨建筑的发展 ,才能创作出优秀的作品 ,屹立在世界的东方     

The discovery of polyacetylene film: The dawning of an era of conducting polymers

This lecture is not directly related to our discovery and development of conducting polymers to which the Nobel Prize in Chemistry in 2000 was awarded. However, I would like to present my previous work that I had carried out just before we reached the discovery of chemical doping. I do hope my talk will be of use for you the audience to deepen your understandings by learning what had happened before and how we did reach the idea of chemical doping.     

听课·作业·写字

课堂是学生学习知识的主要场所,听课是接受知识的主要途径,集中注意是听好课堂讲授的心理保证,预习有助注意的集中。通过预习对所学的内容进行探寻性了解,既可提高兴趣,又为认知重组提供了基础。写作业是对已学的内容进行练习从而达到巩固学习的目的。使知识牢固的根本办法是理解它,理解的记忆是深刻的记忆。课后复习,在复习中弄清道理,弄清道理后再练习、写作业,这是事半功倍的学习方法。写字和做人一样,讲究平正,平淡无浊,正直不奸。开设写字课、书法课,是集审美、品德和知识于一炉的举措。     

Effects of potable water filtration sludge on the rheological behaviour of one-coat plastering mortars

This work describes the study of the potential use of the sludge generated in potable water filtration/cleaning operations (waste material) as workability-aid in rendering/plastering mortars. A commercial mortar was used as reference and several formulations were investigated, containing sodium phosphate enriched waste material instead of the enriched bentonite traditionally used as workability-aid and setting retarder in cement-based compositions.

Fresh mortars were characterised in terms of plasticity as a function of elapsed time. Rheological behaviour was studied with a specific rheometer. The same setting delay can be obtained with the use of the enriched sludge even by using lower contents of the additive (0.25%), but the workability window tends to be narrower. Fluidity assured by the tested admixtures is mostly controlled by changes in yield stress values of the paste.

The replacement of bentonite by an equivalent amount of sodium phosphate-added waste material (ca. 0.25 wt.%) is technically feasible.     

What's in your wash tank?

Sellers of aqueous cleaning agents have but two things to offer: their proprietary formulation and their service. So they protect the former because it's their lifeblood. And users value the latter because they need to know as much as they can about the formulation—to fulfill OSHA's Hazard Communication (HAZCOM) requirements, to manage or troubleshoot their “bug pond” where the spent formulation is treated, or just to get clean parts. This, column will attempt to generally identify the composition of your aqueous cleaning agent.     

Optical probes of polydiethynylsilanes

We have applied a variety of optical probe techniques for studying the ground-state properties, photoexcitations, and optical nonlinearities of the novel class π-conjugated polymers incorporating Si (or Ge), the polydiethynylsilanes (PDES): [(HCC)₂SiR₂]_x, where R = alkyl, phenyl, etc. Our measurements imply that the PDES backbone structure consists of units of four-membered rings alternately connected to CH and SiR₂ units; thus it can be regarded as an almost degenerate ground state (AB)_x with a band gap at 2 eV. The PDES are therefore the second class of conducting polymers that can support soliton excitations. Using the photomodulation spectroscopy technique, we have found in PDES photogeneration of charged solitons similar to that in trans-(CH)_x, as predicted by theory. However, due to the short average conjugation length in PDES films, the soliton energy levels are split by end-effects confinement. We have also found at 2 eV χ⁽³⁾ = 3 × 10^{− 9} esu, which decays in a record time of 135 fs, followed by a slower decay component of 750 fs, without a long tail even at higher laser intensities.     

二氧化碳对X60钢微生物腐蚀行为影响

利用失重法和扫描电镜研究了CO₂与嗜热SRB共存条件下X60钢在海底污泥和污水中的腐蚀行为.结果表明:CO₂饱和条件下,随着温度的升高,污泥和污水中腐蚀速率均增加,且含SRB的污泥和污水中X60钢的腐蚀速率均大于不含SRB的腐蚀速率,SEM观察表明,X60钢遭受的破坏以点蚀为主;随着CO₂分压的增大,X60钢的腐蚀速率增大,且污泥中腐蚀速率大于污水中腐蚀速率.     

Magnetic ordering in ternary RMn2Ge2 compounds (R = Tb, Ho, Er, Tm, Lu) from neutron diffraction study

The compounds RMn₂Ge₂ (R = Tb, Ho, Er, Tm, Lu) have been investigated by neutron diffraction. TbMn₂Ge₂ is a collinear ferrimagnet with the Mn and Tb moment aligned along the c axis (μ_TB = 8.81(59) μ_B: μ_Mn = 2.21(44) μ_B). HoMn₂Ge₂ exhibits incommensurale ordering below 2.1 K characterized by two wavevectors at 1.3 K: q₁ = (0.1543(4), 0.1543(4), 0) and q₂ = (0.210(1), 0.007(1), 0). The Mn sublattice remains antiferromagnetic down to 1.3 K (μ_Mn = 2.38(6) μ_B). The Er moments order ferromagnetically below 5.5 K in ErMn₂Ge₂ (μ_Mn = 6.81(31) μ_B). The moments are perpendicular to the c axis. The Mn sublattice remains antiferromagnetic down to 1.8 K (μ_Mn = 2.34(18) μ_B). The magnetic structure of TmMn₂Ge₂ is characterized by the propagation vector (0.0.1/2). the Tm moments lying in the basal plane. The ordering of the Tm moments yields a canting of the Mn moments (τ = 21(3)°); μ_Tm = 6.63(18) μ_B; μ_Mn = 2.28(27) μ_B). The antiferromagnetic structure of LuMn₂Ge₂ has been determined (μ_Mn = 2.32(14) μ_B). The evolution of the magnetic properties of the heavy rare earth compounds RMn₂Ge₂ is discussed.     

Better materials can reduce the threat from terrorism

... you will never have a perfect defense, not against the bullet, not against the tank and not against nuclear weapons. What you can do is vastly complicate an attacker’s calculations, blunt his force and save millions of lives. For more information, contact Toni Maréchaux at National Research Council, 2101 Constitution Ave. NW, National Materials Advisory Board, Washington, D.C., 20418; e-mail tmarecha@nas.edu.; www.national academies.org/nmab.     

汽车模具企业的发展提升简

模具企业要在国际模具行业中立于不败之地,应该认真分析总结在过去所作的工作中,有什么东西值得发扬,有什么东西值得改进,有哪些地方需要向别人学习。否则,我们就落后于别人,失掉工作,失掉市场,被市场经济淘汰。本文浅谈模具企业如何发展提升才能赢得市场的一些观点。     

Application of a F.E.M. code to the evaluation of the friction law of a tungsten part at high temperatures

The mechanics laboratory of VALDUC has been working for many years in metal forming: its activities go from punching to milling through extruding and sheet metal forming.

The need of numerical modelling has been clearly demonstrated these recent years, as it can be a very cost-effective mean of research and development tool, and, furthermore, it can give more information than any other instrumented experiment. But, it is first necessary, in order to do the right use of a finite element code, to elaborate some validation tests which have to be done with extensively care. Then, we must also perform, or find in literature or purchasing brochure, some characterisation tests so as to know how the material behaves and to be able to use a constitutive law.

As each manufacturing process is very peculiar, it is very difficult to find a code well adapted to every problem; so we have decided that the best way was to develop our own software in conjunction with a french school with already some knowledge in the corresponding field (INSA de LYON) and other industrial partners (among them FORTECH). The code, called POLLUX, that we have now, can be described with the following advantages:

• * it possesses an elasto-visco-plastic formulation, which gives an accurate value of the hydrostatic pressure; this last is the main parameter of damage models and is important for further improvement in friction field.

• * the code handles both mechanical and thermal simulation which are coupled.

We will compare POLLUX's results with some upsetting tests which have been conducted on tungsten cylinders of 20 mm diameter and with an height of 30 mm, with circles machined at the top and bottom faces to follow precisely the sliding. Experiments were conducted at temperatures ranging between 600 and 1000°C, under primary vacuum with quasi-isothermal conditions. This study has been focused on the following parameters:

• * first, adapting a constitutive law based on the experimental upsetting load.

• * determining the best friction coefficient distribution for the TRESCA and the COULOMB laws, for each temperature, and then analysing the evolution of these coefficients versus temperature, trying to find the best fit law in order to use it in the thermo-mechanical version of the code.

• * see how the strain variations correspond between experimental and predicted results.

     

Challenged by your outside vendor

High levels of quality and process control can be retained in outsourced jobs. The key is to convey to your vendor your expectation that standards will be met and adhered to through quality assurance specification and quality control procedures. These should contain complete information covering general and detailed requirements.     

The Center for Microanalysis of Materials

“Excuse me,” said a graduate student that I’ve not seen before, “I’d like to get some time on the Auger.” “Fine” I reply, “If you are going to need a lot of time, Nancy will train you so that you can use the machine yourself. If it’s only a small project, she’ll work with you. In either case, see Nancy to get a session scheduled.” Shaking off the last remnants of sleep, I realize that I’ve forgotten the most important question, “Oh, just a minute …. Why? … I mean, what do you want to find out?” And so begins a discussion which leads to the recommendation that, instead of Auger spectroscopy, the student use a combination of SIMS and STEM. We schedule time appropriately.     

Effects of milling, doping and cycling of NaAlH4 studied by vibrational spectroscopy and X-ray diffraction

The effects of milling and doping NaAlH₄ with TiCl₃, TiF₃ and Ti(OBuⁿ)₄, and of cycling doped NaAlH₄ have been investigated by infrared (IR) and Raman spectroscopy and X-ray powder diffraction. Milling and doping produce similar effects. Both decrease the crystal domain size (900 Å for milled and 700 Å for doped, as compared to 1600 Å for unmilled and undoped NaAlH₄) and increase anisotropic strain (by a factor >2.5, mainly along c). They also influence structure parameters such as the axial ratio c/a, cell volume and atomic displacement amplitudes. They show IR line shifts by 15 cm⁻¹ to higher frequencies for the Al–H asymmetric stretching mode ν₃, and by 20 cm⁻¹ to lower frequencies for one part of the H–Al–H asymmetric bending mode ν₄, thus suggesting structural changes in the local environment of the [AlH₄]⁻ units. The broad ν₃ bands become sharpened which suggests a more homogeneous local environment of the [AlH₄]⁻ units, and there appears a new vibration at 710 cm⁻¹. The Raman data show no such effects. Cycling leads to an increase in domain size (1200–1600 Å), IR line shifts similar to doped samples (except for TiF₃: downward shift by 10 cm⁻¹) and a general broadening of the ν₃ mode that depend on the nature of the dopants. These observations support the idea that some Ti diffusion and substitution into the alanate lattice does occur, in particular during cycling, and that this provides the mechanism through which Ti-doping enhances kinetics during re-crystallisation.     

Synthesis, luminescence and quantum yields of Eu(III) mixed complexes with 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1,10-phenanthroline-N-oxide

The new complex tris(4,4,4-trifluoro-1-phenyl-1,3-butanedionate)(1,10-phenanthroline-N-oxide)europium(III) has been synthesized, characterized, and its photophysical properties (excitation and luminescence spectra, and quantum yields) investigated down to 4.2 K. A similar complex containing H₂O instead of phenNO molecules was also investigated for comparison. The more pronounced temperature dependence of the quantum yield q and the larger difference between the q values upon ligand and direct Eu³⁺ excitation for the hydrated compound show that there are other quenching processes operative, besides the expected multiphonon relaxation via the H₂O vibrations. The results clearly show that the substitution of the water molecules by phenNO leads to greatly enhanced quantum yields (i.e. 30% vs. 66%, upon ligand excitation at 300 K) and longer ⁵D₀ lifetimes (380 μs vs. 670 μs respectively). This can be ascribed to a more efficient ligand-to-metal energy transfer and to less efficient non-radiative ⁵D₀ relaxation processes.     

连铸铁泥制备纳米α-Fe2O3及光催化去除Cr(Ⅵ)

连铸铁泥富含铁元素,资源化利用是必然选择。以连铸铁泥为原料,采用水热法成功制备纳米α-Fe₂O₃,实现高附加值利用。研究结果显示,所制备的纳米α-Fe₂O₃为均匀的球状介孔结构,比表面积为48.78 m2/g,平均晶粒尺寸约40~50 nm,较大的比表面积与较小的晶粒尺寸可提供大量的光催化活性位点,有利于提升材料的光催化性能。将纳米α-Fe₂O₃应用于Cr(Ⅵ)脱除的光催化剂,显示较好的Cr(Ⅵ)废水脱除效果,180 min内去除率可达100%。经过5次循环后,Cr(Ⅵ)的去除效率仍可达到89.2%,说明纳米α-Fe₂O₃具有良好的可重复使用性。对光催化去除Cr(Ⅵ)的反应机理进行研究,表明光生电子(e-)、羟基自由基(·OH)和超氧阴离子(·O₂-)是参与Cr(Ⅵ)去除的主要活性物质。本研究可将工业副产品连铸铁泥转化为高附加值的纳米材料,并为重金属废水脱除提供了一个新的思路,有较高的实际应用价值。     

New organic superconductor, λ-(BETS)2GaCl4 and metal-insulator transition of BETS conductor with magnetic anions (BETS = bis(ethlenedithio)tetraselenafulvalene)

Crystal structutres and electronic properties of BETS compounds with tetrahedral anions, MX₄ (BETS = bis(ethylenedithio)tetraselenafulvalene; M = Ga, Fe, In; X = Cl, Br) were examined. The salts can be classified into two types (κ, λ). All the compounds with so-called κ-type molecular arrangements retained metallic behavior down to 4 K. λ-(BETS)₂GaCl₄ demonstrated a a superconducting transition around 8 K. Whereas λ-(BETS)₂FeCl₄ with the isomorphic λ-type structure exhibited a sharp metal-insulator transition at 8 K. Low-temperature X-ray studies showed that the structural difference between λ-GaCl₄ and λ-FeCl₄ salts is very small. The structure analysis of κ-(BETS)₂FeCl₄ at 18 K indicated that the FeCl₄ anion has approximately C_3v symmetry. The ESR measurements revealed the high-spin state of Fe³⁺ in λ-FeCl₄ salt and and low-spin state in κ-FeCl₄ salt. ESR intensities of κ- and λ-FeCl₄ salts suggested antiferromagnetic interaction between Fe³⁺ ions.