The Polymerization of Metal-Containing Vinylic Monomers of Iron and Tungsten with Metal–Carbon σ Bonds

A series of metal-containing vinylic monomers of the type and was homopolymerized using 2,2-azobisisobutyronitrile (AIBN) as the free-radical initiator. These monomers were also copolymerized with styrene in the presence of AIBN. These compounds represent a class of organometallic polymers in which the metal is bonded to the polymer backbone via a metal–carbon bond. The new compounds were characterized by IR and ¹H NMR spectroscopy as well as scanning electron microscopy, gel permeation chromatography, and thermoanalytical studies (DSC and TGA). The properties of the new organometallic polymers are discussed.     

Urea-N uptake by dasheen (Colocasia esculenta L. Schott) in relation to the fertilizer placement method

Urea has become the most important N carrier in many parts of the world and its reaction when added to soil is unique in many ways. Two field experiments were therefore undertaken using¹⁵N to investigate the uptake efficiency of the added urea-¹⁵N which was banded in Experiment I and broadcast in Experiment II. In both experiments the uptake efficiencies were not affected by N-rate and cropping system (Exp. I) or crop residue management (Exp. II) and averaged 17.4 and 16.9% respectively. These low values were supported by evidences of high losses; high pH increases following urea application (volatilization), downward movement of N (leaching), and cycles of waterlogged and well drained conditions in the soil (de-nitrification). Evidence of leaching at least down to 30 cm in the profile was observed in the first experiment where urea was banded but not in experiment II where it was broadcast. The proportion of N in the crop that was derived from added urea (%Ndff) was 57.7% and 36.4% in experiments I and II respectively, suggesting that band application resulted in a higher proportion of the added N in the root zone compared to that for broadcast application. The results indicate the need to investigate other management strategies, such as higher application frequencies and placement closer to the root zone, in order to improve the uptake efficiency of added urea-N in upland rainfed dasheen.     

RFID-enabled item-level product information revelation

We consider a homogeneous product market and the incentive for oligopolists to share item-level product information with their customers. Enabled by Radio Frequency Identification technology, each firm has the option to record and reveal item-level information of a proportion of its products. We consider a two-stage game where each firm first decides its production plan and then determines its level of information revelation. With a constant clearance discount rate, we derive pure strategy equilibria that are subgame perfect and demonstrate that complete information sharing is the unique Nash equilibrium for the game when the common demand is volatile and that no information revelation is the unique Nash equilibrium when demand is not volatile. Furthermore, we show that the Nash equilibrium is the same with a decreasing clearance discount rate and that neither complete information revelation nor zero information revelation is consistent with an equilibrium with an increasing discount rate. Results are similar in a duopoly non-homogeneous product market scenario.     

Enhancement of sterol synthesis by the monoterpene perillyl alcohol is unaffected by competitive 3-hydroxy-3-methylglutaryl-CoA reductase inhibition

Monoterpenes such as limonene and perillyl alcohol (PA) are currently under investigation for their chemotherapeutic properties which have been tied to their ability to affect protein isoprenylation. Because PA affects the synthesis of isoprenoids’ such as ubiquinone’ and cholesterol is the end product of the synthetic pathway from which this isoprenoid pathway branches’ we investigated the effects of this compound upon cholesterol metabolism in the colonic adenocarcinoma cell line SW480. PA (1 mM) inhibited incorporation of ¹⁴C-mevalonate into 21–26 kDa proteins by 25% in SW480 cells. Cholesterol (CH) biosynthesis was assessed by measuring the incorporation of ¹⁴C-acetate and ¹⁴C-mevalonate into 27-carbon-sterols. Cells treated with PA (1 mM) exhibited a fourfold increase in the incorporation of ¹⁴C-acetate but not ¹⁴C-mevalonate into cholesterol. Mevinolin (lovastatin)’ an inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase’ at 2 μM concentration’ inhibited CH synthesis from ¹⁴C-acetate by 80%. Surprisingly’ concurrent addition of mevinolin and PA did not significantly alter the stimulatory effects of PA. As observed differences in ¹⁴C-acetate and ¹⁴C-mevalonate precursor labeling could indicate PA affects early pathway events’ the effects of this monoterpene on HMG-CoA reductase activity were evaluated. Unexpectedly’ 1 mM PA did not stimulate activity of this enzyme. Consistent with its action as a reversibly bound inhibitor’ in washed microsomes’ 2 μM mevinolin pretreatment increased reductase protein expression causing a 12.7 (±2.4)-fold compensatory HMG-CoA reductase activity increase; concurrent treatment with 1 mM PA attenuated this to a 5.3 (±0.03)-fold increase. Gas chromatographic analysis confirmed CH was the major lipid present in the measured thin-layer chromatography spot. Since ¹⁴C-acetate incorporation into free fatty acid and phospholipid pools was not significantly affected by PA treatment’ nonspecific changes in whole acetate pool sizes were not indicated. Because increases in endogenous CH synthesis should result in compensatory changes in exogenous sterol utilization’ the effects of PA upon low density lipoprotein (LDL) receptor activity were evaluated. Consistent with the observed increases in CH synthesis’ 1 mM PA decreased ¹²⁵I-LDL internalization to 50% of the fetal bovine serum control; concurrent addition of 2 μM mevinolin attenuated this effect to a reduction of 80% of the control value. Data suggest that in certain colonic tumor cells PA strongly affects cholesterol metabolism via a mechanism of action that is insensitive to the HMG-CoA reductase inhibitor mevinolin.     

Fouling in a Centritherm Evaporator With Whey Solutions

Fouling caused by sweet cheese whey and reconstituted whey powder solutions was studied in a Centritherm evaporator, with the behavior being estimated by measuring the change in the overall heat transfer coefficients with the time. It was found that there was no fouling detectable for the reconstituted whey powder solution. For sweet cheese whey, the fouling rate was strongly linked with the evaporating temperature and temperature difference. Visual observation showed that the deposit layer on the evaporator surface was very thin and soft, and like the type A milk deposit described by other investigators. A high velocity of liquid film delayed the formation of deposit on the surface. Some interactions between the evaporation temperature, feed flow rate, rotating speed, and temperature difference are discussed. The fouling is caused by denaturation of bovine serum albumin following a second-order rate reaction.     

Vulnerabilities in Chen and Deng's RFID mutual authentication and privacy protection protocol

As incorporation of RFID (Radio Frequency IDentification) tags in a wide variety of applications increase, there is a need to ensure the security and privacy of the entity to which these tags are attached. Not surprisingly, this is a very active area as attested by the large number of related published research literature. Recently, the journal engineering applications of artificial intelligence published a paper by Chen and Deng (2009) where the authors propose a mutual authentication protocol for RFID. This protocol has fundamental flaws that can be readily taken advantage by a resourceful adversary. We identify and discuss these vulnerabilities and point out the characteristics of this protocol that exposes it to these vulnerabilities.     

The use of computer technology in university teaching and learning: a critical perspective

Abstract  Despite huge efforts to position information and communication technology (ICT) as a central tenet of university teaching and learning, the fact remains that many university students and faculty make only limited formal academic use of computer technology. Whilst this is usually attributed to a variety of operational deficits on the part of students, faculty, and universities, this paper considers the wider social relations underpinning the relatively modest use of technology in higher education. The paper explores how university use of computer technology is shaped into marginalized and curtailed positions by a variety of actors. From the 'writing' of ICT at a national policy level through to the marginalization of ICT within the lived 'student experience', a consistent theme emerges where computer technology use is constructed in limited, linear, and rigid terms far removed from the creative, productive, and empowering uses which are often celebrated by educational technologists. In the light of such constraints, the paper considers how these dominant constructions of a peripheral and limited use of ICT may be challenged by the higher education community. In particular, it concludes by reflecting on current critical thinking about how educational technologists can foster a more expansive and empowered use of computer technology within university settings.     

Do caregivers still care?

Plasma levels of medium molecular peptides (MMP) were measured and Paramecium test was made in 28 patients with acute otitis media purulenta (AOMP). Of these, 18 patients had complicating mastoiditis. The baseline results of both tests correlated with clinical symptoms of systemic endogenic intoxication. Paramecium test returned to normal after one day of treatment. Informative value of this test fell with detoxication contrary to plasma MMP value which correlated with the degree of intoxication and remained informative through detoxication being able to show even residual subclinical toxicity. The MMP test is a method of choice in assessing intoxication in patients with AOMP and its complications.