the estimation of thyroxine in human plasma by an electrophoretic technique

A new method for the determination of thyroxine in blood is described. It relies upon the quantitative dependence of the distribution of thyroxine between albumin and thyroxine-binding protein when exogenous 131I-labelled thyroxine is added to serum in vitro. Preliminary results suggest an accuracy in the estimate of the hormone of about 5–10%. Results in a group of patients whose plasma P.B.I, levels were also determined are given and shown to be similar.

Self-Assembly of Rod-Terminally Tethered Three-Armed Star-Shaped Coil Block Copolymer: Investigation of the Presence of the Branching in the Coil to the Self-Assembled Behavior

Self-assembled behavior of rod-terminally tethered three-armed star-shaped coil block copolymer melts was studied by applying self-consistent-field lattice techniques in three-dimensional (3D) space. Similar to rod-coil diblock copolymers, five morphologies were observed, i.e., lamellar, perforated lamellar, gyroidlike, cylindrical and sphericallike structures, while the distribution of the morphologies in the phase diagram was dramatically changed with respect to that Of rod-coil diblock copolymers.

Probing the kinetics of single molecule protein folding

We propose an approach to integrate the theory, simulations, and experiments in protein-folding kinetics. This is realized by measuring the mean and high-order moments of the first-passage time and its associated distribution. The full kinetics is revealed in the current theoretical framework through these measurements. In the experiments, information about the statistical properties of first-passage times can be obtained from the kinetic folding trajectories of single molecule experiments ( for example, fluorescence). Theoretical/simulation and experimental approaches can be directly related. We study in particular the temperature-varying kinetics to probe the underlying structure of the folding energy landscape. At high temperatures, exponential kinetics is observed; there are multiple parallel kinetic paths leading to the native state. At intermediate temperatures, nonexponential kinetics appears, revealing the nature of the distribution of local traps on the landscape and, as a result, discrete kinetic paths emerge. At very low temperatures, exponential kinetics is again observed; the dynamics on the underlying landscape is dominated by a single barrier.

Species of rare earth(III) and calcium(II) in the presence of L-aspartic acid and L-arginine

Rare earth (III)-Asp-Arg and Ca(II)-Asp-Arg systems were studied by potentiometric titration under physiological conditon. The species of each system were determined. The distribution of Tb (III) and Ca(II) species was discussed, as well as in the quaternary system of Tb(III)-Ca(II)-Asp-Arg.

FACTORS AFFECTING THE ROLE OF SIO2 IN MGCL2-SUPPORTED ZIEGLER-NATTA COPOLYMERIZATION CATALYSTS

This paper describes the roles of silica (SiO2), the butoxy ligand (-OBu) and ethyl benzoate (EB) on ethylene/1-butene copolymerization with MgCl2/SiO2-supported titanium catalysts. The distribution of SiO2 and of the elements Mg and Ti was observed by means of an energy-dispersed X-ray microanalyzer on a scanning electron microscope (SEM). An inversed Si/Mg ratio results, at invariant Ti/Mg ratio and -OBu content, in higher catalyst efficiency and higher comonomer incorporation, with a correspondingly decreased crystallinity of the copolymers. Thus, the inert carrier SiO2 favors copolymerizability, as seen from the values of the reactivity ratios. The copolymer compositional distribution is also affected by the SiO2 content, as seen from the DSC curves of the copolymers. As to the copolymer morphology, addition of SiO2 makes the copolymer particles larger and more uniform.

Effect of heavy metals (Cd, Cu) on the gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminaria japonica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal (Cd) distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu tip to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning (the first day) of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd- and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods. All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.

The stability zone of gas hydrate in the slope of East China Sea and neighboring trough basin area

We analyze the distribution of temperature and heat flow of the sea floor sediment in the area of East China Sea slope and West basin area of the Okinawa Trough. Based on the Sonar Buoy and OBS data, 6 velocity layers are recognized, each of which has velocity of 1.8(1.8 similar to 2.2) km/s,2.2(2.0 similar to 2.5)km/s,2.8 (2.7 similar to 3.2)km/s,3.4 similar to 3.6km/s,4.2(4.1 similar to 4.7)km/s and 5.1km/s, respectively. The upper velocity layer of 1.8 similar to 2.2 km/s corresponds to the Quaternary sediment stratum. The layer with velocity 3.4 similar to 4.2km/s is the Pliocene sediment stratum. The area that is suitable for stable existence of gas hydrate by the temperature and pressure is 70,000km(2) about 1/10 the total area of East China Sea. The thickness of the stability zone ranges from 400m (Middle Part of Okinawa Trough) to 1100m (North and South Part of Okinawa Trough). The Quaternary and Pliocene layers are suitable for stable exitence of gas hydrate. According to the tectonic stability and heat flow, the north part and south part of the Okinawa Trough are the most perspective area for the gas hydrate explorations.

The characteristics of BSRs and their derived heat flow on the profile 973 in the northeastern South China Sea

Processing of a recently acquired seismic line in the northeastern South China Sea by Project 973 has been conducted to study the character and the distribution of gas hydrate Bottom-Simulating Reflectors (BSRs) in the Hengchun ridge. Analysis of different-type seismic profiles shows that the distribution of BSRs can be revealed to some extents by single-channel profile in this area, but seismic data processing plays an important role to resolve the full distribution of BSRs in this area. BSR' s in the northeastern South China Sea have the typical characteristics of BSRs on worldwide continental margins: they cross sediment bed reflections, they are generally parallel to the seafloor and the associated reflections have strong amplitude and a negative polarity. The characteristics of BSRs in this area are obvious and the BSRs indicate the occurrence of gas hydrate-bearing sediments in the northeastern South China Sea. The depth of the base of the gas-hydrate stability zone was calculated using the phase stability boundary curve of methane hydrate and gas hydrate with mixture gas composition and compared with the observed BSR depth. If a single gradient geothermal curve is used for the calculation, the base of the stability zone for methane hydrate or gas hydrate with a gas mixture composition does not correspond to the depth of the BSRs observed along the whole seismic profile. The geothermal gradient therefore changes significantly along the profile. The geothermal gradient and heat flow were estimated from the BSR data and the calculations show that the geothermal gradient and heat flow decrease from west to east, with the increase of the distance from the trench and the decrease of the distance to the island arc. The calculated 2 heat flow changes from 28 to 64 mW/m(2), which is basically consistent with the measured heat flow in southwestern offshore Taiwan.

Probability distribution of random wave-current forces

Based on the second-order solutions obtained for the three-dimensional weakly nonlinear random waves propagating over a steady uniform current in finite water depth, the joint statistical distribution of the velocity and acceleration of the fluid particle in the current direction is derived using the characteristic function expansion method. From the joint distribution and the Morison equation, the theoretical distributions of drag forces, inertia forces and total random forces caused by waves propagating over a steady uniform current are determined. The distribution of inertia forces is Gaussian as that derived using the linear wave model, whereas the distributions of drag forces and total random forces deviate slightly from those derived utilizing the linear wave model. The distributions presented can be determined by the wave number spectrum of ocean waves, current speed and the second order wave-wave and wave-current interactions. As an illustrative example, for fully developed deep ocean waves, the parameters appeared in the distributions near still water level are calculated for various wind speeds and current speeds by using Donelan-Pierson-Banner spectrum and the effects of the current and the nonlinearity of ocean waves on the distribution are studied. (c) 2006 Elsevier Ltd. All rights reserved.

Sources and distribution of aliphatic and polyaromatic hydrocarbons in sediments of Jiaozhou Bay, Qingdao, China

The composition and distribution of aliphatic (n-alkanes) and polyaromatic hydrocarbons (PAHs) were measured for the surface sediments collected at 25 sites from Jiaozhou Bay, Qingdao, China. Total n-alkanes and PAH concentrations ranged from 0.5 to 8.2 mu g/gdw and 0.02 to 2.2 mu g/gdw, respectively, and the distribution of both n-alkanes and PAHs showed large spatial variations in the bay. The distribution of PAHs in the sediments was predominated by the three or more ring compounds. High hydrocarbon levels were generally found in the areas associated with high anthropogenic impact and port activities in the bay. The calculated hydrocarbon indexes suggest that petroleum contamination was the main source of n-alkanes, while both pyrolytic and petrogenic sources contributed PAHs to the surface sediments of Jiaozhou Bay. In comparison to other polluted coastal sediments, the level of contamination from both aliphatic hydrocarbons and PAHs in Jiaozhou Bay sediments is relatively low at the present time. (c) 2005 Elsevier Ltd. All rights reserved.

A three-dimensional coupled physical-biological model study in the spring of 1993 in the Bohai Sea of China

A three-dimensional (3-D) coupled physical and biological model was used to investigate the physical processes and their influence on the ecosystem dynamics of the Bohai Sea of China. The physical processes include M-2 tide, time - varying wind forcing and river discharge. Wind records from I to 31 May in 1993 were selected to force the model. The biological model is based on a simple, nitrate and phosphate limited, lower trophic food web system. The simulated results showed that variation of residual currents forced by M, tide, river discharge and time-varying wind had great impact on the distribution of phytoplankton biomass in the Laizhou Bay. High phytoplankton biomass appeared in the upwelling region. Numerical experiments based on the barotropic model and baroclinic model with no wind and water discharge were also conducted. Differences in the results by the baroclinic model and the barotropic model were significant: more patches appeared in the baroclinic model comparing with the barotropic model. And in the baroclinic model, the subsurface maximum phytoplankton biomass patches formed in the stratified water.

The floristic of the family Gramineae of Karakorum and Kunlun area, China

There are 47 genera and 161 species of Gramineae except the cultivated species in the area of the Karakorum and Kunlun Mountains. The results of research on the distribution of the genera and species of Gramineae in the Karakorum and Kunlun Mountains show that (1) The Gramineae mainly contains elements of North Temperate, rich Old Word Temperate and other Temperate. It is obvious that the floristic nature of Gramineae in the Karakorum and Kunlun Mountains is the North Temperate; (2) All Pantropic genera can stretch to the Temperate Zone in this region, which all parts of the Pantropic type are the Temperate nature to a certain degree. For example, Erianthus ravennae from mediterranean to the Karakorum and Kunlun Mountains through the Central Asia; (3) As most genera of Grasses are the type of Temperate and the Frigid Zone, they have distinct floristic characteristics of mountainous and plateau flora such as Orinus, Alopecurus, Elymus, Trisetum, Littledalea, Elytrigia, Stephanachne and Paracolpodium etc. All of these indicate adaptive phenomenon of alpine specialization and cold-xerophilization on Grasses in this area; (4) Endemic genus of Gramineae is absent due to its nature and history and the endemic species are also rare in the Karakorum and Kunlun Mountains. Most of the genera with one or fewer species have originated from its relative and widespread genera, such as Ptilagrostis from Stipa, Timouria from Achnatherum, and so on; (5) Flora of the Karakorum and Kunlun Mountains is most closely related to the flora of Tibet, and is also extensively to its adjacent areas.

Relationship between the molybdenum phases and the conversion of n-butane over Mo/HZSM-5

The conversion of n-C4H10 was undertaken on MoO3/HZSM-5 catalyst at 773-973K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO3 on HZSM-5 can be readily reduced by n-C4H10 to MoO2 at 773 K and MoO2 can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO2 with n-C4H10 below 893 K is alpha-MoC1-x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO3 to MoO2 (>773 K) or the carburization of MoO2 to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C4H10 can proceed catalytically on both Mo2C/HZSM-5 and MoO2/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the, activity for Mo2C/HZSM-5 is much higher than that for MoO2/HZSM-5. (C) 2002 Elsevier Science B.V. All rights reserved.

Locational distribution of gene functional classes in Arabidopsis thaliana

Riley, M. C., Clare, A., King, R. D. (2007). Locational distribution of gene functional classes in Arabidopsis thaliana. BMC Bioinformatics 8, Article No: 112 Sponsorship: EPSRC / RAEng

Spatial distribution of upland beetles in relation to landform, vegetation and grazing management

Dennis, P., Aspinall, R. J., Gordon, I. J. (2002). Spatial distribution of upland beetles in relation to landform vegetation and grazing management. Basic and Applied Ecology, 3 (2), 183?193. Sponsorship: SEERAD RAE2008