Air-Oxidation of Starch Using Quinquevalent Vanadium as Catalyst

Air-oxidation of corn starch in the presence of ammonium meta vanadate at 35–40°C and pH 9 has been studied. The resulting oxidized starch contained more carbonyl but less carboxyl as compared to an industrial oxidized starch. However, the presence of undesirable amounts of the catalyst imparted extremely high viscosity to the oxidized starch. The ultraviolet irradiation was found to have a pronounced effect on the air oxidation of starch in the presence of ammonium meta vanadate. Increased carboxyl content was observed in the UV light catalyzed oxidized starch.     

Thermomechanical characterization of thermoplastic polyimides to improve the chain collaboration via ureidopyrimidone endcaps

In this report, we explored the effect of incorporating ureidopyrimidone (UPy) linkers in a series of polyimides (PIs) previously studied in our laboratory. The polymers consist of an aromatic diamine monomer with a methylene linker, 4,4′’‐methylenebis (2,6‐dimethylaniline), used to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to decrease rigidity. The polymers were designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links, with an aim to improve the mechanical characteristics. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that the UPy linkers with their four‐hydrogen bond sites are introduced to connect the chains in series. The connection strengthens the chain interactions and increases the range of the thermal and mechanical properties of the PI. Furthermore, the connecting regions are an important component to preserve the thermal stability of PIs while maintaining the processability. The polymers were characterized by FTIR, nuclear magnetic resonance, GPC, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, microhardness, and tensile testing. POLYM. ENG. SCI., 59:2231–2246, 2019. © 2019 Society of Plastics Engineers     

Kinetic study of olefin polymerization with a supported metallocene catalyst. III. Ethylene homopolymerization in slurry

A kinetic study of ethylene homopolymerization is conducted with a supported unbridged metallocene catalyst in a slurry reactor. The effects of operational parameters such as the reaction temperature and pressure on kinetics are investigated. The kinetic parameters which have been determined for this particular catalyst from previous gas phase studies are used in a slurry reactor model to predict the polymerization behavior under various reaction conditions. The experimental data compare favorably with the predictions from this model. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2901–2917, 2001     

Kinetic study of olefin polymerization with a supported metallocene catalyst. II. Ethylene/1‐hexene copolymerization in gas phase

A kinetic study of ethylene/1‐hexene copolymerization is conducted with a supported metallocene catalyst in a gas‐phase reactor. The investigation into the kinetics of ethylene/1‐hexene copolymerization includes the effects of operational parameters such as the reaction temperature, pressure, and comonomer concentration. The large variations in gas‐phase composition using only an initial charge of 1‐hexene are illustrated by experiment. To remedy this, the ability to control the comonomer composition of 1‐hexene online for the entire duration of the reaction is demonstrated. Online perturbation techniques are implemented to determine key kinetic parameters such as the activation energies for propagation and catalyst deactivation. From pressure perturbation results, a reaction rate order close to 1 is obtained for ethylene in the presence of 1‐hexene. Finally, all the parameters obtained from the study are compared to those determined from ethylene–propylene (E–P) copolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1096–1119, 2001     

Acetone absorption in UV‐irradiated polycarbonate

Isothermal acetone absorption in UV‐irradiated polycarbonate (PC) was investigated at temperatures from ?23 to +25°C. The crystalline fraction of PC increased with UV dose. The anomalous transport data were analyzed based on Harmon's model which includes contributions from Case I transport characterized by the diffusion coefficient, D, and Case II transport characterized the velocity, v. Diffusion coefficients were monitored by both mass uptake using the model (D and v), and movement of the sharp front (D_f). Plots of log of D, v, and equilibrium swelling ratio (ESR) versus 1/T exhibited similar features. That is, plots were linear and superimposable for all doses at the higher temperatures, and exhibited a transition temperature and then a linear region that varied with dose. The values of D, D_f, and v increased with increasing dose, whereas the ESR decreased with dose. The direction of Case II transport was opposite to that of Case I diffusion during which time, sorbed solvent was expelled from the samples. Results are discussed in terms of a solvent‐induced change in lattice structure at the lower temperatures and in terms of UV radiation effects on the PC matrix that enhance solvent crystallization. POLYM. ENG. SCI., 58:1174–1183, 2018. © 2017 Society of Plastics Engineers     

Safeguarding the data warehouse

Data warehousing and the Internet are regarded as the two most important changes to the information systems landscape in the past few years. Although they are agents of powerful change, their deployment presents many challenges and opportunities. Here is outlined one set of challenges that has emerged with the convergence of the Internet and data warehousing security.     

A Receding Horizon Control algorithm for adaptive management of soil moisture and chemical levels during irrigation

The capacity to adaptively manage irrigation and associated contaminant transport is desirable from the perspectives of water conservation, groundwater quality protection, and other concerns. This paper introduces the application of a feedback-control strategy known as Receding Horizon Control (RHC) to the problem of irrigation management. The RHC method incorporates sensor measurements, predictive models, and optimization algorithms to maintain soil moisture at certain levels or prevent contaminant propagation beyond desirable thresholds. Theoretical test cases are first presented to examine the RHC scheme performance for the control of soil moisture and nitrate levels in a soil irrigation problem. Then, soil moisture control is successfully demonstrated for a center-pivot system in Palmdale, CA where reclaimed water is used for agricultural irrigation. Real-time soil moisture, temperature, and meteorological data were streamed wirelessly to a field computer to enable autonomous execution of the RHC algorithm. The RHC scheme is demonstrated to be a viable strategy for achieving water reuse and agricultural objectives while minimizing negative impacts on environmental quality.     

Timing constraint specification and analysis

Real‐time programmers have to deal with the problem of relating timing constraints associated with source code to sequences of machine instructions. This paper describes an environment to assist users in the specification and analysis of timing constraints. A timing analyzer predicts the best and worst case bounds for these constrained portions of code. A user interface for this timing analyzer was developed to depict whether these constraints were violated or met. A user is allowed to specify timing constraints within the source code of a C program. The user interface also provides three different methods for interactively selecting portions of programs. After each selection the corresponding bounded times, source code lines, and machine instructions are automatically displayed. Users are prevented from only selecting portions of the program for which timing bounds cannot be obtained. In addition, a technique is presented that allows the timing analysis to scale efficiently with complex functions and loops. The result is a user‐friendly environment that supports the user specification and analysis of timing constraints at a high (source code) level and retains the accuracy of low (machine code) level analysis. Copyright © 1999 John Wiley & Sons, Ltd.     

Use of latex teat dip with germicide during the prepartum period

The efficacy of an acrylic latex barrier teat dip with germicide on new infections at parturition was tested on 113 cows and heifers during the prepartum period. A split udder design was used in which right quarters were undipped controls and left quarters were dipped with latex dip once daily for approximately 14 d prior to parturition. Distal streak canal swabs were taken from all quarters prior to the beginning of dipping, and all cows were quarter sampled in duplicate at drying off, parturition, and the first 5 consecutive wk of lactation. All quarters received antibiotic therapy at drying off. Excluding infections detected by distal streak canal swabs, the number of new infections at parturition in control and dipped quarters was 32 and 36. New infections at parturition in control and dipped quarters were Staphylococcus aureus, 2 and 2; coagulase-negative staphylococci, 8 and 9; stretptococci, 10 and 12; coliforms, 8 and 8; and others, 4 and 5. Differences were not significant. These results suggest no benefit to use of prepartum latex teat dip with germicide on new infections at parturition.     

Influence of sodium chloride and potassium bicarbonate on udder edema and selected blood parameters

Forty-four first lactation heifers were fed NaCl (23 and 136 g/d) or KHCO3 (0 and 272 g/d) beginning 42 d prepartum and continuing to 10 d postpartum to study the influence of these salts on udder edema and selected blood parameters. Addition of NaCl or KHCO3 singly to the diet significantly increased the severity of udder edema, but the addition of both salts did not increase edema. Blood samples were collected from the jugular vein at 42 d prepartum and at 1, 3, and 10 d postpartum. Hematocrit and pH were measured on whole blood and osmolarity on serum samples. Concentrations of protein, Ca, Na, K, and Cl in serum were also determined. Serum total proteins were reduced and serum osmolarity was increased in the cows fed NaCl. Blood pH was elevated in the group receiving KHCO3. Serum K was higher in groups receiving supplemental KHCO3. No differences across dietary treatments were observed in the other parameters. Although addition of NaCl or KHCO3 to the diet increased the severity of udder edema, the exact mechanism causing edema could not be determined.