Function space valued Markov model for electric arc furnace

In this paper, a novel approach for using a function space Markov chain-like to model a nonlinear, highly time-varying load such as an electric arc furnace (EAF) is proposed. After identifying the state space, this approach generalizes the original state case (where state is an element being analyzed) to a function case (in which one analyzes the cycle-vector as an element) and uses the same fundamental idea of Markov-like modeling, thus making it more convenient and powerful for EAF current/voltage prediction in a distribution system. Several approximations for the cycle-vector are investigated to reduce the complexity of the formulation and the burden on computation. The predictions derived from fast Fourier transform (FFT) frequency decomposition method appear to give better results than other proposed approximations based on both accuracy and efficiency indexes. Such an approach is further extended for harmonic compensation with an active harmonic filter (AHF) in a distributed system.     

Extraction from Food and Natural Products by Moderate Electric Field: Mechanisms,Benefits, and Potential Industrial Applications

Several extraction techniques have been proposed recently as the food industry is seeking alternatives to tedious classical methods. Moderate electric field (MEF) extraction at low and high temperatures offers several advantages such as enhancing product quantity and quality as well as saving time and energy. This method has gained interest as a preferred extraction technique among researchers. This review is devoted to introducing the principles, mechanisms, and recent progress in the MEF extraction technique. The parameters influencing MEF treatment are also discussed and performances are compared to conventional extraction methods. Considerations for industrial development of MEF as well as its drawbacks are also discussed. MEF extraction is applicable to a wide range of food materials and offers several benefits such as reducing extraction time and energy and also enhancing the extract's quality and yield. Optimizing process parameters, such as treatment time and temperature, electric field intensity, and frequency, along with raw material selection and preparation can boost the performance of a MEF system. Further investigations on safety and sustainability of this novel technique are required prior to commercial applications.     

Enantioenriched Calcium‐(R)‐5,5′,6,6′,7,7′,8,8′‐Octahydro‐BINOL (H8‐BINOL): An Efficient Catalyst for the Creation of a Quaternary Stereocenter#

An efficient catalyst for the creation of a quaternary stereocenter has been developed utilizing easily available, eco‐friendly CaCl₂ and applied for enantioselective carbon‐carbon bond forming reactions. Among the surveyed ligands, it was found that (R)‐5,5′,6,6′,7,7′,8,8′‐octahydro‐BINOL‐Ca ( 2f ) gave maximum ee (72%) with excellent yields.     

Nonholonomic motion planning: steering using sinusoids

Methods for steering systems with nonholonomic c·onstraints between arbitrary configurations are investigated. Suboptimal trajectories are derived for systems that are not in canonical form. Systems in which it takes more than one level of bracketing to achieve controllability are considered. The trajectories use sinusoids at integrally related frequencies to achieve motion at a given bracketing level. A class of systems that can be steered using sinusoids (claimed systems) is defined. Conditions under which a class of two-input systems can be converted into this form are given     

Viscoelastic behaviour of acrylic bone cements

Local contact stresses at the bone-cement interface are thought to play an important role in the initiation of component loosening. A reduced-modulus bone cement can lower these local contact stresses. The viscoelastic properties of such a cement raised the question of long term subsidence of the implant system. In this study, the viscoelastic properties of a reduced-modulus bone cement were compared with standard polymethylmethacrylate, PMMA, bone cement using stress relaxation tests. Unconstrained stress relaxation tests were performed at 37 degrees C in an aqueous environment by applying 1%, 2.5%, and 5% strains on bone cement specimens and monitoring the diminishing load for 100 h. The initial rapid stress relaxation occurring over the first hour and the steady state stress relaxation occurring between 15 and 100 h were analyzed. A fast stress diminution occurred in PBMMA specimens indicating that, in a total hip arthroplasty application, PBMMA bone cement would transfer the stress quickly and distribute it over a larger area of endosteal bone surface. Steady state stress relaxation experiments showed a significant difference in 2.5% and 5% stress relaxation values (P < 0.05) between PMMA and PBMMA specimens, but not at the 1% stress values. Length measurements indicated that the viscoelastic PBMMA specimens demonstrated little recovery after 100 h of imposed strain whereas the elastic PMMA specimens showed substantial recovery. This seems to indicate relatively larger subsidence rates in unconstrained PBMMA specimens compared to PMMA specimens. In vivo, the cement is surrounded by endosteal bone at the outer side and by an implant on the inner side. Therefore, constrained creep tests are necessary to obtain the data required for an assessment of in vivo subsidence.     

Corticothalamic connections of extrastriate visual areas in rhesus monkeys

Corticothalamic connections of extrastriate visual areas were studied by using the autoradiographic anterograde tracing technique. The results show that the medial extrastriate region above the calcarine sulcus projects mainly to the lateral pulvinar (PL), medial pulvinar (PM), and lateral posterior (LP) nuclei. In addition, the dorsal portion of the medial region has connections to the lateral dorsal (LD) as well as to intralaminar nuclei. The dorsolateral extrastriate region projects strongly to the PL and LP nuclei, to the PM and inferior pulvinar (PI) nuclei, and to the LD and intralaminar nuclei. The lateral extrastriate region above the inferior occipital sulcus (IOS) has strong connections to both the PL and PI nuclei and has minor projections to the PM and oral pulvinar nuclei. The ventrolateral extrastriate region below the IOS projects mainly to the PI nucleus and to the caudal portion of the PL nucleus and has some projections to the PM nucleus. The ventromedial extrastriate region medial to the occipitotemporal sulcus has strong connections with the ventral and medial sectors of the PI nucleus. This region also projects to the caudal portion of the PL nucleus and has minor connections to the LP nucleus. Finally, the annectant gyrus projects to the PL nucleus and to the rostral portion of the PI nucleus and has minor connections to the PM nucleus. Thus, the medial and dorsolateral extrastriate regions are related mainly to the PL and LP nuclei as well as to intralaminar nuclei. In contrast, the ventrolateral and ventromedial regions are connected strongly with the PI nucleus. This connectional organization appears to reflect functional differentiation at the cortical level.     

Synthesis and antitumor evaluation of bis[(pivaloyloxy)methyl] 2'-deoxy-5-fluorouridine 5'-monophosphate (FdUMP): a strategy to introduce nucleotides into cells

The bis[(pivaloyloxy)methyl] [PIV2] derivative of 2'-deoxy-5- fluorouridine 5'-monophosphate (FdUMP) was synthesized as a potential membrane-permeable prodrug of FdUMP. The compound was designed to enter cells by passive diffusion and to revert to FdUMP after removal of the PIV groups by hydrolytic enzymes. The most convenient preparation of PIV2FdUMP was by condensation of 2'-deoxy-5-fluorouridine (FUdR) with PIV2 phosphate in the presence of triphenylphosphine and diethyl azodicarboxylate (the Mitsunobo reagent). PIV2FdUMP was stable in the pH range 1.0-4.0 (t1/2 > 100 h). It was also fairly stable at pH 7.4 (t1/2 = 40.2 h). In 0.05 M NaOH solution, however, it was rapidly degraded (t1/2 < 2 min). In the presence of hog liver carboxylate esterases, PIV2FdUMP was converted quantitatively to the mono-[(pivaloyloxy)methyl] [PIV1] analogue PIV1FdUMP. After a 24 h incubation, only trace amounts of FdUMP (1-3%) were observed, indicating that PIV1FdUMP is a poor substrate for carboxylate esterases. In mouse plasma, PIV2FdUMP was rapidly metabolized, first to PIV1FdUMP and then to FdUMP. With continued incubation, FUdR was formed, presumably due to further catabolism of FdUMP by plasma phosphatases or 5'-nucleotidases. Since PIV1FdUMP is a poor substrate for carboxylate esterase, the cleavage of the second PIV group is most likely mediated by plasma phosphodiesterases. The rate of degradation of PIV2FdUMP in the presence of acid and alkaline phosphatase, 5'-nucleotidase, or spleen phosphodiesterase was the same as that in buffer controls, indicating that the compound is not a substrate for these nucleotide catabolizing enzymes. The concentration of PIV2FdUMP and its 3'-O-acetyl ester (PIV2 3'-O-Ac-FdUMP) required to inhibit the growth of Chinese hamster ovary (CHO) cells in vitro to less than 50 cells per colony was 5 x 10(-6) M, the same as that required for 5-fluorouracil (FU). Both nucleotide prodrugs showed the same growth-inhibitory potency against a mutant CHO cell line that was 20-fold resistant to FU (CHO/FU). Administered intraperitoneally at optimal dosage for 5 consecutive days, PIV2FdUMP and PIV2 3'-O-Ac-FdUMP were as effective as FU at prolonging the life spans of mice bearing intraperitoneally implanted P388 leukemia. Both prodrugs retained full therapeutic activity against a P388 subline resistant to FU. Collectively, these data indicate that PIV2FdUMP and PIV2 3'-O-Ac-FdUMP are effective membrane-permeable prodrugs of FdUMP.     

Xanthine oxidase activity associated with arterial blood pressure in spontaneously hypertensive rats

Recent evidence in vivo indicates that spontaneously hypertensive rats (SHR) exhibit an increase in oxyradical production in and around microvascular endothelium. This study is aimed to examine whether xanthine oxidase plays a role in overproduction of oxidants and thereby may contribute to hypertensive states as a consequence of the increasing microvascular tone. The xanthine oxidase activity in SHR was inhibited by dietary supplement of tungsten (0.7 g/kg) that depletes molybdenum as a cofactor for the enzyme activity as well as by administration of (-)BOF4272 [(-)-8-(3-methoxy-4-phenylsulfinylphenyl)pyrazolo(1,5-alpha)-1,3, 5-triazine-4-monohydrate], a synthetic inhibitor of the enzyme. The characteristic elevation of mean arterial pressure in SHR was normalized by the tungsten diet, whereas Wistar Koto (WKY) rats displayed no significant alteration in the pressure. Multifunctional intravital videomicroscopy in mesentery microvessels with hydroethidine, an oxidant-sensitive fluoroprobe, showed that SHR endothelium exhibited overproduction of oxyradicals that coincided with the elevated arteriolar tone as compared with WKY rats. The tungsten diet significantly repressed these changes toward the levels observed in WKY rats. The activity of oxyradical-producing form of xanthine oxidase in the mesenteric tissue of SHR was approximately 3-fold greater than that of WKY rats, and pretreatment with the tungsten diet eliminated detectable levels of the enzyme activity. The inhibitory effects of the tungsten diet on the increasing blood pressure and arteriolar tone in SHR were also reproducible by administration of (-)BOF4272. These results suggest that xanthine oxidase accounts for a putative source of oxyradical generation that is associated with an increasing arteriolar tone in this form of hypertension.