Fixed-width confidence interval of log odds ratio for joint binomial and inverse binomial sampling

This article provides a two-stage procedure to develop a fixed-width confidence interval of log odds ratio in a joint binomial and inverse binomial setting where the stopping rule is obtained by adopting a two-stage procedure on the number of index subjects for the inverse sampling. A purely sequential version of this procedure is also studied. Different asymptotic results associated with the procedures are obtained. The findings are supported by detailed simulation study followed by one data example.     

A symptotic robustness of sequential confidence intervals and the connection with influence functions

The robustness of sequential confidence intervals is studied by considering contamination with probability ε of the basic underlying distribution in a so-called gross errors model. Asymptotic theory is considered when d → 0, where the prescribed length of the interval is 2d, and simultaneously ε ? ε(d) → 0. A general theorem, in a distribution free setting, is given which provides expressions for the asymptotic coverage probability and the asymptotic distribution of the stopping variable. The results depend on the rate of ε(d)/d as d → 0 and on the contaminating distribution. If the latter distribution is degenerate, it turns out that the influence functions of the above mentioned two estimators used in the construction of the procedure, appear in the expressions for the asymptotic coverage probability and the asymptotic distribution of the stopping variable respectively. This shows how the sequential procedure inherits the robustness properties of the estimators concerned and how this is quantified. The general theorem is specialized to two procedures for the estimation of the mean of a symmetric distribution. Results of Monte Carlo studies indicate agreement between the asymptotic theory and the actual behavior of the procedures.     

Estimate of confidence intervals for geometric mean diameter and geometric standard deviation of lognormal size distribution

Confidence of particle size distribution, which is the size distribution of sample particles selected from a large population with lognormal size distribution, has been studied theoretically. Theoretical equations were derived from the basic formulas commonly used in statistics to estimate confidence intervals for geometric mean diameter and geometric standard deviation. Computer simulation has provided size distribution of sample particles by random sampling in order to confirm the theoretical equations. For both geometric mean diameter and geometric standard deviation, the confidence intervals were calculated so that both values of population were placed approximately in the middle of the intervals. The tendencies for the intervals to decrease with an increase in sample particle number and/or significance level, and with a decrease in geometric standard deviation, were reasonable in statistics. The proposed theoretical equations should be useful for estimating confidence of lognormal size distribution.     

离心式压缩机油系统常见故障及事故处理

在油系统运行中,会出现一些常见故障,如处理不当,会造成工艺系统不稳定,甚至发生机组跳车等事故。分析事故发生原因,正确处理故障,保证机组安全稳定运行。     

Copolymerization of 4-methyl- and 4-methoxyphenyl acrylates with glycidyl methacrylate: Synthesis,characterization, reactivity ratios,and application as adhesives for the leather industry

Copolymers of 4-methyl- and 4-methoxyphenyl acrylates with glycidyl methacrylate having different copolymer compositions were synthesized in 1,4-dioxan using benzoyl peroxide as a radical initiator at 70 ± 0.5°C. The composition of the monomers in the copolymers were calculated using ¹H-NMR spectroscopy by comparing the integral values of well-separated aromatic and alifatic proton peaks. The reactivity ratios were calculated by Fineman-Ross, Kelen-Tudos, and extended Kelen-Tudos methods. The copolymers were characterized by ¹H-NMR and proton decoupled ¹³C-NMR spectroscopic techniques. Gel permeation chromatography was used for determining the $\overline {M_w }$ and $\overline {M_n }$ and polydispersity indexes of the copolymers. Thermal stability of the homo- and copolymers was calculated using thermogravimetric analysis, while differential scanning calorimetry was utilized in determining the glass transition temperature. Copolymers of suitable composition were chosen for curing reactions with diethanolamine in chloroform. The cured resins were tested as adhesives for leather-leather bonding at different temperatures (50, 90, 100, and 110°C). It was found that copoly(MOPA-GMA) at 50°C gave the best adhesive property over all other samples tested. © 1996 John Wiley & Sons, Inc.     

Transformations,properties, and exact solutions of unsteady axisymmetric boundary layer equations for non-Newtonian fluids

Unsteady axisymmetric boundary layer equations for power-law non-Newtonian fluids are analyzed. A number of new exact solutions containing arbitrary functions and free parameters are constructed using generalized or functional separation of variables. The solutions are obtained using a Crocco-type transformation reducing the order of the equations examined and simpler point transformations. Along with the exact solutions to axisymmetric boundary layer equations, some new exact solutions to planar boundary layer equations for non-Newtonian fluids are constructed. Several properties have been discovered that allow the exact solutions of the unsteady axisymmetric boundary layer equations to be generalized by including additional arbitrary functions therein. All results refer to an arbitrarily shaped streamlined solid of revolution.     

Copolymerization of 4-cyanophenyl acrylate with methyl methacrylate: synthesis, characterization and determination of monomer reactivity ratios

A novel acrylic monomer, 4-cyanophenyl acrylate (CPA) was synthesized by reacting 4-cyanophenol dissolved in methyl ethyl ketone with acryloyl chloride in the presence of triethylamine as a catalyst. Copolymers of CPA with methyl methacrylate (MMA) at different composition was prepared by free radical solution polymerization at 70 ± 1 °C using benzoyl peroxide as an initiator. The copolymers were characterized by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques. The solubility tests were checked in various polar and non polar solvents. The molecular weight and polydispersity indices of the copolymers were estimated by using gel permeation chromatography. The glass transition temperature of the copolymers increases with increases MMA content. The thermal stability of the copolymer increases with increases in mole fraction of CPA content in the copolymer. The copolymer composition was determined by using ¹H-NMR spectra. The monomer reactivity ratios determined by the application of linearization methods such Fineman–Ross (r ₁ = 0.535, r ₂ = 0. 0.632), Kelen–Tudos (r ₁ = 0.422, r ₂ = 0.665) and extended Kelen–Tudos methods (r ₁ = 0.506, r ₂ = 0. 0.695).     

Copolymerization of 4-cyanophenyl methacrylate with methyl methacrylate: Synthesis,characterization and determination of monomer reactivity ratios

Summary A novel methacrylic monomer, 4-cyanophenyl methacrylate (CPM) was synthesized by reacting 4-cyanophenol dissolved in methyl ethyl ketone (MEK) with methacryloyl chloride in the presence of triethylamine as a catalyst. Copolymers of CPM with methyl methacrylate(MMA) at different composition was prepared by free radical solution polymerization at 70±1 °C using benzoyl peroxide as initiator. The copolymers were characterized by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques. The solubility of the polymers was tested in various polar and non polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in mole fraction of MMA content. The thermal stability of the copolymer increases with increases in mole fraction of CPM content in the copolymer. The copolymer composition was determined by using ¹H-NMR spectroscopy. The monomer reactivity ratios estimated by the application of linearization methods such as Fineman-Ross (r₁=2.524±0.038, r₂=0.502±0.015), Kelen-Tudos (r₁=2.562±0.173, r₂=0.487±0.005) and extended Kelen-Tudos methods (r₁=2.735±0.128, r₂=0.4915±0.007).     

Copolymerization of 4-biphenyl methacrylate with glycidyl methacrylate: Synthesis, Characterization, thermal properties and determination of monomer reactivity ratios

Summary The methacrylic monomer, 4-biphenylmethacrylate (BPM) was synthesized by reacting 4-biphenyl phenol dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in presence of triethylamine as a catalyst. The copolymers of BPM with glycidyl methacrylate (GMA) were synthesized by free radical polymerization in EMK solution at 70±1 °C using benzoyl peroxide as a free radical initiator. The copolymerization behaviour was studied in a wide composition interval with the mole fractions of BPM ranging from 0.15 to 0.9 in the feed. The copolymers were characterized by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques. The solubility was tested in various polar and non polar solvents. The molecular weight and polydispersity indices of the polymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in BPM content. The thermogravimetric analysis of the polymers showed that the thermal stability of the copolymer increases with BPM content. The copolymer composition was determined using ¹H-NMR spectra. The monomer reactivity ratios were determined by the application of conventional linearization methods such as Fineman-Ross (r₁=0.392 ± 0.006, r₂ = 0.358 ± 0.007, Kelen-Tudos (r₁= 0.398 ± 0.004, r₂= 0.365 ± 0.013) and extended Kelen-Tudos methods (r₁= 0.394 ± 0.004, r₂= 0.352 ± 0.006).     

E- and P-selectin: differences, similarities and implications for the design of P-selectin antagonists

Selectins form a family of Ca2+ -dependent carbohydrate binding proteins that mediate the initial step of leukocyte recruitment in the inflammatory process. Blocking of selectins is therefore considered a promising therapeutic approach to treat acute and chronic inflammatory diseases which are caused by excessive extravasation of leukocytes. This mini-review highlights the major structural differences between E- and P-selectin and summarizes the resulting strategies for the design of selectin antagonists.     

Copolymerization of 2-methyl-N-1,3-thiazole-2-ylacrylamide with glycidyl methacrylate: synthesis, characterization, reactivity ratios and biological activity

The free-radical copolymerization of 2-methyl-N-1,3-thiazole-2-ylacrylamide monomer (TMA) with glycidyl methacrylate (GMA) was carried out in 1,4-dioxane at 65 ± 1 °C using azobisisobutironitril (AIBN) as an initiator. The copolymers were characterized by FTIR, ¹³C-NMR and ¹H-NMR spectroscopic methods. The copolymer compositions were determined by elemental analysis. The weight-average and number-average molecular weights of the copolymers were obtained by gel permeation chromatography (GPC). The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. Thermal properties of the polymers were also studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The monomer reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tudos and Fineman–Ross linearization methods. The reactivity ratios indicated a tendency toward for alternation. The thermal decomposition activation energies of the polymers were evaluated by Ozawa method. The antibacterial and antifungal effects of the copolymers were also investigated on various bacteria and fungi. All the products showed moderate activity against different strains of bacteria and fungi.     

Comparison of SFI,DSC and NMR methods for determining solid-liquid ratios in fats

Dilatometry (SFI) has gained wide acceptance for the characterization of solid-liquid contents of fats over approximately the past 15 years. In more recent times, wide-line nuclear magnetic resonance (NMR) has been used for this purpose. Still more recently the differential scanning calorimetry (DSC) technique has been used to determine solid-liquid contents. These three techniques were used to determine the properties of seven fats and oils which represent a cross section of commercially available materials. These products were blended into 14 different compositions and the solid-liquid contents were determined by the three methods. A comparison is made on the results obtained on the various samples by SFI, NMR and DSC techniques. The results of each procedure are compared according to fat composition. One of 10 papers to be published from the Symposium “Wide-Line Nuclear Magnetic Resonance” presented at the AOCS Meeting, Minneapolis, October 1969.     

浅谈空气自动监测系统监测数据质量保证及异常数据的处理

文章分析了空气自动监测系统运行过程中,如何建立仪器校准、定期的零点和跨度漂移检查、对异常监测数据的科学处理等监测数据质量保证制度,以确保空气自动监测系统稳定可靠运行、监测数据准确完整,为环境管理提供科学的依据。     

Cross-linking photocopolymerization of dodecyl methacrylate with oxyethylene glycol dimethacrylates: Kinetics and reactivity ratios

The photo-induced copolymerization of dodecyl methacrylate (DDM) with five oxyethylene glycol dimethacrylates (OEGDM) was investigated. Effects of the monomer ratio and of the length of dimethacrylate spacer group on the polymerization kinetics, the extent of the after-effect and pendant double bond content in the polymerization product were studied and the reactivity ratios estimated. For systems containing OEGDM with short spacers between the methacrylate groups, R_p^max reached the highest value at certain monovinyl/divinyl monomer ratio. This phenomenon was discussed in terms of the behavior of the reaction diffusion parameter (as a function of monomer ratio and conversion). Determination of the reactivity ratios by five calculation methods showed that r₁ (DDM) values were lower than 1 and the r₂ (OEGDM) values were higher than 1 indicating that the polymer formed at the beginning of the reaction is more densely cross-linked than that formed in the final reaction stages.     

Copolymers of poly(n-alkyl acrylates): synthesis, characterization, and monomer reactivity ratios

Poly(n-alkyl acrylate) copolymer reactivity ratios were determined for n-alkyl acrylate monomers of various side-chain lengths n ranging from 6 to 22. Two sets of copolymers were synthesized to less than <10% conversion to evaluate the reactivity ratios. The first set included P(A10-co-A14), P(A10-co-A18), and P(A14-co-A18); while the second set consisted of P(A6-co-A12), P(A6-co-A22) and P(A12-co-A22). Copolymers were formed from monomer mixtures at 25 mol% intervals ranging from 0 through 100 mol%. ¹³C NMR was performed on the homo polymers and the low conversion copolymers to determine the reactivity ratios of the monomers in each copolymer system. It was determined that the reactivity ratios for all monomers examined here were approximately equal to one. Physical properties of the copolymers, including melting point, heat of fusion, and permeation as a function of temperature, of the low conversion polymers were compared to copolymers formed at 100% conversion to demonstrate that these properties are independent of conversion because no composition drift occurs during polymerization.     

Folding of chains with random and edited sequences: similarities and differences

We have investigated the process of protein folding by Monte-Carlosimulation of folding occurring in a simple 3D lattice modelof a protein globule. We have found the range of ‘optimal’temperatures where the native fold is achieved by the Monte-Carloprocess much faster than that by exhaustive sorting of all thechain folds. The ‘optimal’ temperatures are essentiallythe same for different random and lsquo;edited’ sequences(for the latter, the native fold energy is separated by a considerablegap from the energies of other low-energy folds; for randomsequences, this gap is negligible). At the ‘optimal’temperatures, the ‘edited’ chains attain their nativefold faster than the random ones. However, the essence is thatthe native folds of ‘edited’ chains are thermodynamicallystable at temperatures optimal for fast folding, while the nativefolds of random chains are unstable at the temperatures optimalfor fast folding; also, at low temperatures where the nativefolds of random chains are stable, folding kinetics is veryslow. Consequently, stable native folds are formed slowly byrandom sequences and rapidly by the ‘edited’ ones     

Copolymerization of 1-vinylpyrrolidone with N-substituted methacrylamides: monomer reactivity ratios and copolymer sequence distribution

In order to enhance their resistance to polar solvents and their film forming ability compared to these of neat polyvinylpyrrolidone (PVP), water soluble copolymers which combined rather large PVP sequences with ammonium groups were obtained. Free radical copolymerization of 1-Vinyl-2-Pyrrolidone (NVP) with 3-(dimethylamino)propyl-methacrylamide (DMA) and 3-(methacrylamido)propyltrimethyl-ammonium, methylsulfate (TMA) was investigated in water at 68 °C using a water soluble initiator (4,4′-azobis(4-cyanovaleric acid ACVA)). The copolymer samples obtained at low conversion levels (<10%) could not be recovered quantitatively for these particular copolymers. Therefore, a numerical integration modeling, accounting for change in copolymer composition with conversion, was preferred to determine the optimal reactivity ratios from experimental data obtained at moderate conversions. The reactivity ratios (system TMA-NVP: r_TMA 4.47, r_NVP 0.038, system DMA-NVP: r_DMA 5.67, r_NVP 0.37) proved a strong preferential incorporation of the methacrylamide monomers. The reactivity ratios were then used to estimate the copolymer sequence distributions. It is shown that rather large NVP sequences can be obtained with low TMA or DMA initial contents at moderate conversion. Moreover, these copolymers easily formed films which withstood polar solvents and could be readily cross-linked by thermal curing, opening interesting prospects for membrane separation systems.