Characteristics of von Willebrand Factor multiuser in blood clotting

The von Willebrand Factor (vWF) is a large multimeric protein in the blood that aids in blood clotting. It activates the clotting cascade at a specific time and a specific place, which is one of the human body\u27s masterpieces in targeted molecular manipulation. Hydrodynamic or shear force triggers conformational changes of vWF, by which its potency and reactivity are regulated. In this thesis, we take inspiration from novel findings in the vWF experiments, and aim to describe the behaviors observed in this process within the context of polymer science. By understanding this physical principle, we hope to harness nature\u27s ability to help us develop targeted drug therapy, which is capable to deliver drug wherever and whenever needed.After initial introduction of the blood clotting process, we first propose a novel bead- spring model in the presence of infinite medium. Contrary to the classic bead-spring model that each bead is connected by one type of spring, our model\u27s beads are connected by finitely extensible nonlinear elastic (FENE) springs and Hookean springs consecutively. The motivation is that the A2 domain, which undergoes significant unfolding during single molecule stretching experiments, has been proven to be very flexible. Instead of modeling a monomer as one bead, more details inside each monomer and more complexity of vWF multimer has been captured by modeling vWF monomers as a highly flexible A2 domain with relatively very rigid domains on either side of A2. The A2 domain is modeled as a finitely extensible nonlinear elastic (FENE) spring capable of significant extension. At each end of the spring is a spherical bead to represent neighboring rigid domains. Adjacent monomers are connected by a tight harmonic spring1successively to form vWF multimers of desired length. In an effort to validate our mythology and generalize our results quantitatively, vWF multimers represented by this model have been probed to understand a single vWF multimer in both relaxation without flow scenarios and unfolding in response to shear flow circumstances.After investigating flow-induced changes in vWF multimer conformation, we extend our research further to study adhesion of vWF multimer by incorporating a collagen-coated surface to the vWF model in the second section of this thesis. During the blood clotting process, vWF undergoes a counterintuitive adsorption process and here we begin to develop the fundamental model required to understand this process. Because the presence of a pure surface will create a non-monotonic lift force, which greatly facilitate the desorption behavior of vWF multimer even under highly attractive surface, we add another A3 domain and collagen interactions representing by reversible ligand-receptor- type bonds based on bell model kinetics. The bonding and debonding rate between vWF multimers and collagen-coated surface is determined by the energy landscape i.e. binding and unbinding energy of bell model, which are measured by force spectroscopy and were extracted using the Dudko-Hummer-Szabo model under different temperature. The no- slip bond that the tensile force has no influence on the bond is being used firstly to counteract the lift force induced desorption. The results show that the adhesion process is still impeded by bead-wall hydrodynamic interactions, which is different from the experimental observations. The final section of this paper will be focused on the dynamics of vWF multimers in complex geometries, especially in a slit

STRENGTH CHECK OF AIR CONDITIONER PANEL MECHANISM BASED ON FINITE ELEMENT MOTHOD

The virtual prototyping technology and the finite element analysis method were used to simulate the motion mechanism of a type of air conditioner panel in order to reduce the possibility of the mechanism failure at the design stage. First,the motion of air conditioner panel is analyzed by ADAMS software and load is exported. The results show that the overall motion of the panel is stable,but a large speed change occurs when the panel is fully open. The maximum load appears in the process of air conditioning start-up. Second,the software ABAQUS was used to analyze the stress. It is indicated that the maximum stress region is the contact position between the gear and the rack when the air conditioning starts up. The maximum stress area is the contact position for rack and pinion when the panel is fully open. In both cases,the maximum stress values satisfy the strength requirements. Finally,the simulation analysis is verified by experimental results of Lab VIEW platform

IBIL Measurement and Optical Simulation of the D_I Center in 4H-SiC

In this paper, DI defects are studied via experiments and calculations. The 2 MeV H+ is used to carry on an ion-beam-induced luminescence (IBIL) experiment to measure the in-situ luminescence of untreated and annealed 4H-SiC at 100 K. The results show that the luminescence intensity decreases rapidly with increasing H+ fluence, which means the losses of optical defect centers. In addition, the evident peak at 597 nm (2.07 eV) is the characteristic peak of 4H-SiC, and the weak peak between 400 nm and 450 nm is attributed to the DI optical center. Moreover, the first-principles calculation of 4H-SiC is adopted to discuss the origin of DI defects. The optical transition of the defect SiC(CSi)2 from q = 0 to q = 1 is considered the experimental value of the DI defect center

Spatiotemporal variations of CO2 fluxes in a Cynodon-dominated riparian zone of the Three Gorges Reservoir (TGR), China

Aims Riparian ecosystems play an important role in overall ecosystem function, including the global carbon cycle of terrestrial ecosystems, at both landscape and global scales. Yet few studies have reported in situ measurements of CO2 in riparian areas where flooding is a unique disturbance to carbon cycling. Methods At multiple locations across riparian zones (RZ) with different water submergences in Xiangxi Bay (XXB), we studied seasonal variations of CO2 exchange between this Cynodon-dominated community and the atmosphere for 2 years by using static chambers. Important Findings We found that the seasonal changes in CO2 fluxes were apparent and dependent on the biophysical environment. In the beginning of spring, low gross primary productivity (GPP) in lightly flooded zones (LFZ) resulted in a positive net ecosystem exchange (NEE), indicating a net CO2 source. With the increase in temperature, more species and vegetation abundance appeared, and the increased GPP turned the LFZ from a net CO2 source into a sink. This transition seemed predominantly controlled by the physiological growth of vegetation. The mean NEEs, REs and the light-use efficiency (alpha) of the vegetation at HFZ and MFZ were significantly higher than those at LFZ and UFZ. Yet the coefficients of variation (CV) of NEE and RE at MFZ and HFZ were lower than those at LFZ and UFZ. Submergence promoted the emission and uptake of CO2 to the atmosphere. Elongated submergence reduced the number of species and lowered the spatial variability of the RZ, further lowering the variation of the CO2 exchange

Sea-ice loss amplifies summertime decadal CO2 increase in the western Arctic Ocean

http://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr98-06/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr99-k05_leg2/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr00-k06/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr04-05/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr06-04_leg2/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr09-03_leg2/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr10-05_leg2/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr12-e03/

A progressive rise in stomach cancer-related mortality rate during 1970-1995 in Japanese individuals over 85 years of age

A large number of studies have shown a gradual fall in stomach cancer-related mortality rate during the last decade. Here we analyzed the pattern of stomach cancer-related mortality rates in Japanese aged>85 years from 1970 to 1995. We used data for the entire population of Japan. The magnitude of change was measured by relative risk and cause-elimination life tables to distinguish time trends in mortality rates of stomach cancer for individuals over 85 years of age compared with other age groups (55-84 years). In the over-85 age group, stomach cancer mortality increased from 374 in 1970 to 662 in 1995 per 100,000 (77%) for males and from 232 to 296 per 100,000 (27%) for females. Using the 55-59 years group as the reference category, the relative risk increased from 2.3 to 9.9 and from 2.8 to 11.1 in men and women, respectively. The effects of mortality on life expectancy also increased 1.5 times and 1.1 times, respectively. Our results showed a rise of stomach cancer mortality in Japanese aged over 85 years, which paralleled the increase in relative risk and negative contribution to life expectancy. While the mortality of younger age groups is decreasing, the change over from increase to decrease in the over-85 age group is only just beginning.stomach cancer, mortality, age, Japan, old,