Local changes in blood flow within the preovulatory follicle wall and early corpus luteum in cows

Haemodynamic changes are involved in the cyclic remodelling of ovarian tissue that occurs during final follicular growth, ovulation and new corpus luteum development. The aim of this study was to characterize the real-time changes in the blood flow within the follicle wall associated with the LH surge, ovulation and corpus luteum development in cows. Normally cyclic cows with a spontaneous ovulation (n = 5) or a GnRH-induced ovulation (n = 5) were examined by transrectal colour and pulsed Doppler ultrasonography to determine the area and the time-averaged maximum velocity (TAMXV) of the blood flow within the preovulatory follicle wall and the early corpus luteum. Ultrasonographic examinations began 48 h after a luteolytic injection of PGF(2alpha) analogue was given at the mid-luteal phase of the oestrous cycle. Cows with spontaneous ovulation were scanned at 6 h intervals until ovulation occurred. Cows with GnRH-induced ovulation were scanned just before GnRH injection (0 h), thereafter at 0.5, 1, 2, 6, 12, 24 h and at 24 h intervals up to day 5. Blood samples were collected at the same time points for oestradiol, LH and progesterone determinations. Cows with both spontaneous and GnRH-induced ovulation showed a clear increase in the plasma concentration of LH (LH surge) followed by ovulation 26-34 h later. In the colour Doppler image of the preovulatory follicle, the blood flow before the LH surge was detectable only in a small area in the base of the follicle. An acute increase in the blood flow velocity (TAMXV) was detected at 0.5 h after GnRH injection, synchronously with the initiation of the LH surge. At 12 h after the LH surge, the plasma concentrations of oestradiol decreased to basal concentrations. The TAMXV remained unchanged after the initial increase until ovulation, but decreased on day 2 (12-24 h after ovulation). In the early corpus luteum, the blood flow (area and TAMXV) gradually increased in parallel with the increase in corpus luteum volume and plasma progesterone concentration from day 2 to day 5, indicating active angiogenesis and normal luteal development. Collectively, the complex structural, secretory and functional changes that take place in the ovary before ovulation are closely associated with a local increase in the blood flow within the preovulatory follicle wall. The result of the present study provides the first visual information on vascular and blood flow changes associated with ovulation and early corpus luteum development in cows. This information may be essential for future studies involving pharmacological control of blood flow and alteration of ovarian function.     

Suspensions of Iron Oxide Nanoparticles Stabilized by Anionic Surfactants

Two common anionic surfactants, sodium oleate (SO) and sodium dodecyl benzene sulfonate (SDBS) were used to re‐suspend iron oxide nanoparticles in aqueous solutions. At certain SO concentrations, the SO formulations produced highly stable suspensions. In contrast, SDBS‐stabilized nanoparticles exhibited poor stability at all concentrations. The adsorption isotherm of SO on iron oxide nanoparticles revealed that stable suspensions were obtained when the equilibrium SO concentration (after adsorption) reached its critical micelle concentration (CMC). At this “optimal” condition, the maximum SO adsorption was reached, and the zeta‐potential of the particles was highly negative (～ ?50 mV). According to the SO isotherm, this optimal formulation coincided with the formation of a highly compact SO bilayer. The SDBS isotherm, on the other hand, revealed that SDBS is not strongly adsorbed on the surface of iron oxide nanoparticles and that is likely that a patchy, loosely packed bilayer, is formed on the surface of the iron oxide nanoparticles when the equilibrium SDBS concentration reaches its CMC. The DLVO theory confirmed the connection between formulation conditions and the corresponding stability. This works confirmed that the formation of a surfactant bilayer is an important element in producing stable nanoparticle suspensions with anionic surfactants. It was also confirmed that for anionic surfactants, electrostatic repulsions are an important factor in establishing an energy barrier against flocculation. This work also introduced two more elements into the design of nanoparticle suspensions. The first element is that, in order to ensure the best possible dispersion, the surfactant concentration in solution at equilibrium with the adsorbed surfactant should be close or slightly above its CMC. The second element is that the molecular structure of the surfactant should facilitate the formation of closely packed bilayers.     

Sizing of a solar/hydrogen system for high altitude long endurance aircrafts

High altitude long endurance (HALE) aircrafts are aerial platforms operating in the stratosphere, providing relay services for wireless communication networks. These platforms are an alternative to increase the effectiveness of future communication. Nevertheless, the power system is a key part that determines the implementation and feasibility of these platforms. One effective and renewable option to power an HALE aircraft is a photovoltaic system (PVS) with hydrogen storage. In this paper, the simulation of the solar/hydrogen closed loop system is carried out for a parametric combination of the subsystems power. Power consumption of the propeller was determined as a function of the aircraft weight in steady flight and in still air. In order to obtain the optimal nominal powers the efficacies are calculated at hourly intervals over the course of the year by means of an analytical energy balance. The proposed method was implemented in an algorithm, which allows fast estimation of the actual time of flight and the system efficiency. Finally, the energy system of three HALE aircrafts was analyzed in relation of their wing area and total and empty mass.     

Tailoring the Piezoelectric and Relaxor Properties of (Bi1/2Na1/2)TiO3–BaTiO3 via Zirconium Doping

This article details the influence of zirconium doping on the piezoelectric properties and relaxor characteristics of 94(Bi_1/2Na_1/2)TiO₃–6Ba(Zr_xTi_1?x)O₃ (BNT–6BZT) bulk ceramics. Neutron diffraction measurements of BNT–6BZT doped with 0%–15% Zr revealed an electric‐field‐induced transition of the average crystal structure from pseudo‐cubic to rhombohedral/tetragonal symmetries across the entire compositional range. The addition of Zr up to 10% stabilizes this transition, resulting in saturated polarization hysteresis loops with a maximum polarization of 40 μC/cm² at 5.5 kV/mm, while corresponding strain hysteresis measurements yield a maximum strain of 0.3%. With further Zr addition, the ferroelectric order is progressively destabilized and typical relaxor characteristics such as double peaks in the current density loops are observed. In the strain hysteresis, this destabilization leads to an increase of the maximum strain by 0.05%. These changes to the physical behavior caused by Zr addition are consistent with a reduction of the transition temperature T_F‐R, above which the field‐induced transformation from the relaxor to ferroelectric state becomes reversible.     

Urine cotinine as an index of smoking status in smokers during 96-hr abstinence: comparison between gas chromatography/mass spectrometry and immunoassay test strips.

Biomarkers such as carbon monoxide (CO) and cotinine (a nicotine metabolite) are used in tobacco cessation studies to assess smoking status. CO is easy to assess, is inexpensive, and provides immediate results. However, the short half-life of CO may limit its ability to identify smokers who have abstained for several hours. Quantitative methods (e.g., gas chromatography/mass spectrometry, or GC/MS) for measuring urine cotinine, which has a longer half-life, are valid and reliable, though costly and time consuming. Recently developed semiquantitative urine cotinine measurement techniques (i.e., urine immunoassay test strips, or ITS) address these disadvantages, though the value of ITS as a means of identifying abstaining smokers has not been evaluated. The present study examined ITS as a measure of smoking status in temporarily abstaining smokers. A total of 236 breath and urine samples were collected from smokers who participated in two separate studies involving three independent, 96-hr (i.e., Monday-Friday), Latin-square-ordered, abstinence or smoking conditions; a minimum 72-hr washout separated each condition. Each urine sample was analyzed with GC/MS and ITS. Under these study conditions, CO demonstrated moderate sensitivity (83.1%) and strong specificity (100%), whereas ITS assessment showed strong sensitivity (98.5%) and weak specificity (58.5%). In this study of short-term abstinence, ITS classified as nonabstinent nearly half of the samples collected from abstaining smokers. However, it classified nearly all nonabstinent smokers as currently smoking. Validation of ITS using GC/MS results from smokers undergoing more than 96 hr of abstinence may be valuable.     

Response to thermal treatment of a powder metallurgy Fe-0.8 % B-1.3 % C-1.6 %Cr alloy

Argon atomized powders of the Fe-0.8%B-1.3%C-1.6%Cr alloy in the rapid solidification condition as well as the consolidated material were characterized. Consolidation was carried out by extrusion at 1050°C and by hot isostatic pressing at 700°C. The microstructure of powder particles in the rapid solidification condition is dendritic and remains unchanged after hot isostatic pressing. This microstructure is gradually lost after annealing at temperatures above 900°C. The extruded material presents a fine and homogeneous microstructure constituted by small grains of laminar pearlite and spherical M₂₃(B,C)₆ borocarbides of 1.8 μm in size. A martensite microstructure with a uniform dispersion of M₃(B,C) borocementite particles is obtained after annealing at 1095°C 10 min and water quenching. For long austenitization time at 1095°C, a coalescence of borocementite as well as decarburization is observed in the steel. Dilatometric studies, between 20 and 400°C, of samples quenched from 1095°C show the presence of two contraction volume points at 160 and 310°C. At 160°C, the high carbon martensite decomposes into a two phase mixture of metastable carbides and low carbon martensite. At 310°C simultaneous transformation of austenite to ferrite and metastable carbides into cementite occurs.     

Competence of minors to understand, evaluate, and communicate about their psychoeducational problems.

Examined the ability of 43 10–19 yr olds with learning and behavior problems to evaluate and perform in interventions related to their problems under conditions of presumed or explicit consent. Ss performed mathematics problems of varying degrees of difficulty and indicated their affective response to the task, reactions to performance demands, and performance attributions. Despite low academic skills and some deviant behavior, the majority of Ss demonstrated a relatively high level of ability to understand, evaluate, communicate, and perform, as measured by the accuracy of self-estimates of skill, self-explanations of behavior, and on-task functioning. Inaccurate skill estimates and negative reactions to the task were more frequent when consent was presumed rather than explicitly sought. Data suggest that many minors have the competence necessary for effectively participating in treatment decision making. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dithioester functionalization of poly(cyclohexene oxide) and its application to obtain block copolymers

A new method of introducing dithioester groups into the polymer chain of poly(cyclohexene oxide) is reported. It includes the use of diaryliodonium salt and an aromatic dithioacid as a redox couple to initiate the cationic polymerization of cyclohexene oxide. It was found that the dithioacid by itself cannot start the polymerization of cationic polymerizable monomers; however, in combination with a diaryliodonium salt, an exothermic reaction was produced, yielding a thiocarbonylthio‐functionalized polyether. Thermal profiles of the redox polymerizations were determined by means of optical pyrometry. A preliminary study showed that when the poly(cyclohexene oxide) functionalized with dithioester groups was introduced into the radical polymerization of styrene, the polystyryl growing radicals reacted with the dithioester‐functionalized polyether to form a block polymer. The amount of polyether actually incorporated into the block copolymer was calculated to be 70% of the initial amount of poly(cyclohexene oxide)/dithiobenzoic acid charged into the reactor. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008