Alkylation of Benzene with Propylene in the Presence of Organometallic Siloxane

The characteristics of alkylation of benzene by propylene in the presence of 1-chloro-3,3,5,5-tetramethylcycloaluminodisiloxane soluble in liquid benzene at 110 and 130°C and benzene: propylene ratios of 3:1 and 5:1 (molar) were investigated. The high activity of the investigated catalyst is demonstrated.__________Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 39 –41, May – June, 2005.     

Metallurgical Reaction Characteristic for the Combined Blowing Process of Top-Bottom Blown Oxygen and Bottom Blown Natural Gas

The experiment was carried out in a combinedblowing converter.The natural gas was supplied asthe cooling medium for the bottom lance.The blow-ing practice of medium P hot metal(0.30-0.85% [P]) indicated that with better stirringat the bottom of the converter and lower P_(CO),thissteelmgking process was favorable to reduce theamount of [C] and [O] and increase the (P_2O_5)/[P].The maximum rate of dephospborization might behigh up to 0.0a5%/min and the P content in steelcould be reduced to lower than 0.03% by singleslag-forming operation.     

Low capacitance and high isolation bond pad for high-frequency RFICs

A bond pad structure using semi-insulating porous silicon (PS) is proposed for the purpose of reducing the parasitic pad capacitance and increasing the crosstalk isolation characteristics on low resistivity p/sup -//p/sup +/ epi substrates for high-performance CMOS. Our results show that reducing the parasitic pad capacitance by using PS results in a high bond pad resonant frequency of up to 56.2 GHz (assuming wire bond inductance is 2 nH). In addition, the crosstalk reduction is as much as 6/spl sim/31 dB at frequencies up to 40 GHz even when compared to that on conventional p/sup -/ bulk substrate. Such a high-performance bonding pad structure is important for high-frequency RFICs which require high operation frequency and low substrate effect.     

Modulation of protein splicing of the Saccharomyces cerevisiae vacuolar membrane ATPase intein

Protein splicing of the Saccharomyces cerevisiae vacuolar membrane ATPase intein involves four highly coordinated reactions that result in precise cleavage and formation of peptide bonds. In this study, we investigated the roles of the last N-extein residue (-1 residue) and the intein penultimate residue in modulating splicing reactions. Most of the 20 amino acid substitutions at the -1 position had no effect on overall protein splicing but could lead to significant accumulation of thioester intermediates when splicing was blocked by mutation. A subset of -1 substitutions attenuated the initiation of protein splicing and enabled us to demonstrate in vitro splicing of a mesophilic intein containing all wild-type catalytic residues. Substitutions involving the intein penultimate residue allowed modulation of the branch resolution and C-terminal cleavage reaction. Our data suggest that the N-S acyl rearrangement, which initiates splicing, may also serve as the rate-limiting step. Through appropriate amino acid substitutions, we were able to modulate splicing reactions in vitro by change in pH or temperature or addition of thiol reagents. Both insertion and deletion were tolerated in the central region of the intein although splicing or structure of the intein may have been affected.     

板式空气预热器的推广应用

传统形式的空气预热器普遍存在积灰结焦、热管失效、腐蚀及漏风等问题,难以满足装置大型化需要。采用以波纹板片作为传热元件的新型板式空气预热器,克服了上述问题并在石化、化肥等行业上得到了应用。自投用后运行情况良好,同时大幅度降低了装置的运行费用和检修费用。     

Stochastic optimization of regenerative systems using infinitesimalperturbation analysis

We consider the problem of optimizing the steady-state mean of a controlled regenerative process using a stochastic optimization algorithm driven by infinitesimal perturbation analysis (IPA) derivative estimates. We derive IPA derivative estimates for our problem and prove almost sure convergence of the algorithm. The generality of our formulation should encompass a wide variety of practical systems. We illustrate our framework and results via several examples     

Detection of Onchocerca volvulus infection by O-150 polymerase chain reaction analysis of skin scratches

The standard assay for onchocerciasis diagnosis is microscopic detection of parasites in skin snips. Skin snipping is painful and may potentially transmit bloodborne infections. Thus, an alternative method for the diagnosis of onchocerciasis that does not require skin snipping is needed. A polymerase chain reaction (PCR)-based assay was shown to detect the presence of parasite DNA in superficial skin scrapings. Detection of parasite DNA in both skin snips and skin scratches was found to be more sensitive for detecting low-density infections than was microscopic examination of skin snips. The skin scratch PCR assay is minimally invasive and painless and does not present the risk of transmitting bloodborne infections. These properties make the skin scratch an attractive alternative to the skin snip for detecting O. volvulus infection.     

Joint connection level, packet level, and link Layer resource allocation for variable bit rate multiclass services in cellular DS-CDMA networks with QoS constraints

An approximate analytical formulation of the resource allocation problem for handling variable bit rate multiclass services in a cellular direct sequence code-division multiple-access (DS-CDMA) system is presented. The novelty in this paper is that all grade-of-service (GoS) or quality-of-service (QoS) requirements at the connection level, packet level, and link layer are satisfied simultaneously, instead of being satisfied at the connection level or at the link layer only. The analytical formulation shows how the GoS/QoS in the different layers are intertwined across the layers. A complete sharing (CS) scheme with guard channels is used for the resource sharing policy at the connection level. The CS model is solved using a K-dimensional Markov chain. Numerical results illustrate that significant gain in system utilization is achieved through the joint coupling of connection/packet levels and link layer. This can translate to more revenues for network providers and/or lower charges for mobile users.     

Sol-gel ZnO-SiO/sub 2/ composite waveguide ultraviolet lasers

Random laser action with coherent feedback is realized in ZnO-SiO/sub 2/ composite films, which consists of ZnO clusters embedded in SiO/sub 2/ dielectric matrix prepared by sol-gel technique. The films are deposited on silicon substrate with a SiO/sub 2/ buffer layer to form a waveguide structure. Ultraviolet lasing at room temperature is observed from the composite films with ZnO : SiO/sub 2/ molar ratio varying between 1 : 5 and 1 : 30. The corresponding lasing wavelength and linewidth under 355-nm optical excitation are found to be /spl sim/388 nm and less than 0.6 nm, respectively. Our experiment has shown that the proper control of light confinement inside the random cavities leads to coherent random lasing.     

Analysis of continuous sandwich panels in building systems

Applying the flexibility method with suitable compatibility conditions, an extended theory involving integro-differential and ordinary differential equations are developed to analyze multi-span architectural sandwich panels. Experimental and theoretical data are in good agreement.