一种新型二肽甜味剂的合成及表征

以3-环己基-L-丙氨酸、Boc-L-天冬氨酸-4-苄酯为原料合成二肽L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(Ⅰ),以3-羟基-4-甲氧基苯甲醛为原料经过Witting反应、H2还原和DIBAL-H还原三步反应合成3-羟基-4-甲氧基苯丙醛(Ⅱ),然后Ⅰ与Ⅱ在氢气、Pd/C催化作用下进行还原氨化反应,得到目标产物N-[3-(3-羟基-4-甲氧基苯基)丙基]-α-L-天冬氨酰-3-环己基-L-丙氨酸-1-甲酯(Ⅲ),总产率为47%。产物的结构采用IR、~1HNMR、~(13)CNMR和HRMS进行表征,并验证其甜度约为蔗糖的25000倍。合成终产物的最佳工艺条件为:n(Ⅱ)∶n(Ⅰ)=1∶1,Pd/C催化剂用量为反应物总重的10%,体积分数80%的甲醇水溶液为溶剂,反应温度35℃,反应时间20 h。     

钌钯双金属催化剂固载顺序控制及性能

以Al_2O_3、PdCl_2和RuCl_3为原料,采用水溶液浸渍法,通过控制固载顺序、制备流程以及焙烧温度等条件,制得系列负载型Ru Pd双金属催化剂,并用于对苯二甲酸二甲酯(DMT)制取1,4-环己烷二甲酸二甲酯(DMCD)的选择性加氢过程。其中,Ru和Pd的总负载量为0.3%(以催化剂总质量为基准,下同),且m(Ru)∶m(Pd)=1∶1。结果发现,采用先Ru后Pd(Ru-Pd)式固载顺序和浸渍-干燥-浸渍-干燥-焙烧(IDIDC)型制备流程,并在450℃下焙烧后,所得负载型Ru-Pd双金属催化剂的反应性能最佳,在6 MPa、180℃下,DMT转化率为89.6%,DMCD选择性为96.0%,DMCD产率为85.9%。这可能与Ru-Pd中大粒径粒子的形成受到抑制、粒径尺寸和分布更小、比表面积和总孔容更高、表面Pd原子摩尔分数较高以及Ru/Pd物质的量比较低有关。     

Decane reforming reaction over Pt,Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on Y-zeolite

Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on NaY- and HY-zeolite were examined as a catalyst for producing gasoline from n-decane via simultaneous reforming and cracking. The catalysts were prepared by calcining and reducing metal-ion-exchanged Y-zeolite with O₂ and H₂ at 300°C., respectively. Thus prepared catalysts were characterized by hydrogen chemisorption and temperature programmed desorption of ammonia. Pt-Ni/NaY and Pt-Ir/NaY bimetallic catalysts offered the improved activity maintenance compared to Pt/NaY monometallic catalyst. The catalysts supported on HY-zeolite showed higher selectivity toward C₅–C₇ and skeletal isomers of C₅–C₇- and C₈–C₁₀ than those of the catalysts supported on NaY-zeolite, which is a desired characteristic for increasing octane value of gasoline these days. However, deactivation with reaction time was much more pronounced on HY-zeolite-supported catalyst. When the catalyst was prcsulfided with H,S, the stability with time on stream was enhanced and the selectivity was quite different from that of the catalyst before presulfiding. The acidity of Y-zeolite and presulfiding of catalyst greatly influenced the activny, selectivity and stability of Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on Y-zeolite in n-decane reforming reaction.     

拱坝表孔泄流下游消能防冲形式的试验研究

摘 要：针对中型拱坝下游消能防冲形式的选择问题,通过物理模型试验,对比分析了长护坦防护、水垫塘+二道坝和短护坦先冲后护三种布置形式下相应的水力学指标。试验结果表明：长护坦方案时,水垫塘内水流流态较差,底板和护岸易失稳破坏;水垫塘+二道坝方案时,水流流态和各项水力学指标满足要求,但水垫塘和二道坝的造价较高;短护坦先冲后护方案时,冲坑位置及深度均在允许范围内,该方案的应用会受到拱坝下游地质条件的制约。依据短护坦先冲后护的试验成果,提出初步确定短护坦防护范围的方法。本工程下泄的单宽流量较小,根据试验成果及类似工程经验,并结合坝址地质和工程造价因素,推荐消能工布置方案为“短护坦先冲后护”方式。     

负载型钴铜双金属氮化物催化氨分解研究

Co and Mo bimetallic nitrides supported on Mg（Al）O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer （XRD）, NH3 temperature-programmed desorption and mass spectrometer （NH3-TPD-MS）, temperature-programmed desorption and mass spectrometer （TPD-MS）, H2 temperature-programmed surface reaction （H2-TPSR） and activity test. The phases of Co3Mo3N and MoN could be formed on Mg（Al）O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg（Al）O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg（Al）O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.     

Simultaneous hydrolysis and fermentation of pulp mill primary clarifier sludge

Bioconversion of sludge from the primary clarifier of a sulphite pulping operation to ethanol offers a number of advantages over conventional disposal options. The amount of material which must be disposed of is reduced while, at the same time, salable and environmentally friendly fuel-ethanol is produced. In this study, primary clarifier sludge (PCS) was shown to be hydrolysed to produce fermentable sugars at a rate proportional to enzyme loading. Initial (1 hour) hydrolysis rates as high as 12.6 g reducing sugar/L · h were observed at an initial enzyme loading of 10 filter paper units (FPU)/g. Hydrolysis was inhibited by spent sulphite liquor (SSL), an inhibition which could be completely overcome by fermenting the SSL to remove sugars. Surfactants were found to only marginally improve the production of sugars. To reduce the deleterious effects of end product inhibition, single stage simultaneous hydrolysis and fermentation (SHF) was carried out using cellulase enzymes and Saccharomyces cerevisiae.     

A low-cost real time virtual system for postural stability assessment at home

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.     

一次风机节能改造

为解决一次风机出口风压低、火焰无力度、系统功耗高等问题,采用空气悬浮风机对其进行节能改造。拆除原有的一次风机备用风机,在原有底座上安装空气悬浮风机,整体设计安装悬浮风机出口管道。改造后,一次风机出口风压明显增大,煤粉燃烧充分,火焰调整灵活,每小时可节电30kWh,两处对空排放管道加装消声器,降噪效果显著。     

第十九届中国国际塑料橡胶工业展览会与第八届亚太国际橡塑工业展览会特别报道（1）

介绍了第十九届中国国际塑料橡胶工业展览会(Chinaplas2005)与第八届亚太国际橡塑工业展览会(APPlas2005)展出的树脂、助剂等的新产品、新技术等。     

Growth and formation mechanism of sea urchin-like ZnO nanostructures on Si

Sea urchin-like nanostructures of ZnO consisting of ZnO nanowires with blunt faceted ends were grown on Si (100) substrates by oxidation of metallic Zn at 600 °C. ZnO nanowires having a diameter of 30–60 nm and length of 2–4 Μm were in similar shape with uniform diameter along its entire length with well faceted blunt ends. X-ray diffraction and transmission electron microscope analysis showed that the as-grown nanostructures were highly crystalline with wurtzite hexagonal structure having lattice constants of a=b=3.25 å and c=5.21 å. Room temperature photoluminescence (PL) measurements showed a weak near band-edge emission at 380 nm, but a strong green emission at 500–530 nm. A model for vapor-solid (VS) growth mechanism of ZnO nanowires was presented, in which nucleation of ZnO is crucial for the growth of the nanostructures.