Search

Intraocular lens (IOL) implantation surgery is quite effective in the treatment of blindness caused by cataracts. However, in clinical applications, IOLs readily form glistening. This phenomenon usually occurs for a period after IOL implantation ranging from a few months to several years. The molecular mechanism of the formation of glistening in IOLs is still inconclusive. Failure to understand and explain the molecular mechanism of glistening formation greatly hinders the design and application of new glistening-free IOL materials. Here, in this study, we use molecular dynamics simulation methods to conduct in-depth research on the molecular mechanism of the glistening formation of IOLs, aiming to provide a possible molecular mechanism of glistening. Furthermore, based on this molecular mechanism, we propose a novel strategy of a glistening-free material based on a composite design method to reasonably copolymerize several types of molecules or functional groups, so that the glistening phenomenon can be effectively eliminated. The possible molecular mechanism of glistening formation proposed in this research can offer a solid theoretical basis and guidance for the subsequent construction of glistening-free IOL materials.

VIsual Background Extractor (VIBe) is a simple and effective background subtraction model, it is important to choose the threshold according to different environments. A new method based on the VIBe is presented which uses the adaptive threshold. We give a new description of the similarity degree without threshold, and then use the energy minimization model to combine the spatial information and show that dynamically choosing threshold in our kernel estimates at each individual pixel can significantly improve results. To compare with the traditional VIBe algorithms, a synthetic test SABS and a real world test I2R are used. Experiment shows that the presented method is on average 10% better than the traditional VIBe in accuracy.

Pose estimation is a thoroughly studied problem in computer vision. But in some realistic scenarios, reference points cannot lie within camera’s field of view (non-intervisible). In this article, planar mirror is placed in front of body, allowing the camera to observe reflection of reference points which can characterize body coordinate. We can form an equation system related to transformation between camera coordinate and body coordinate. We propose an unattached and linear approach to solve and optimize transformation of camera-to-body without any prior information of planar mirror configuration. Additionally, we analyze the sensitivity of our algorithm. We present a number of simulations and experiments to prove that our formulation significantly improves accuracy and robust.

Active Traffic Management (ATM) is a tool that can stabilize traffic flow and improve safety by dynamically managing and controlling traffic based on the prevailing traffic conditions. This paper analyzes the traffic flow characteristics of G6 freeway in Beijing of China based on survey data. The relationships among traffic parameters such as standard deviation of speeds (SDS), average speed and occupancy are established in order to calibrate the critical thresholds for the activation of a VSL system in ATM. Furthermore, the control logic of a VSL system is proposed based on the relationships between SDS and other parameters.

The debromination of deca-bromodiphenyl ester (BDE209) is one of the most important processes in itsremoval from the environment. Despite numerous experimental studies improved the efficiency of poly brominateddiphenyl ethers (PBDEs') debromination, few studies focused on the mechanism. This work provides a preliminaryinvestigation on studying the debromination mechanism of BDE209 with density functional theory (DFT). Experimentalresults suggest a stepwise process catalyzed by Ni⁄Fe bimetallic nano particles. So, a potential debromination mechanismof BDE209 via a four-membered ring transition state has been proposed. The B3LYP calculations indicate loweractivation energies catalyzed by Ni relative to Fe, which agrees with the experimental result that a much higherdebromination efficiency with Ni⁄Fe bimetallic nano particles than nano zero-valent iron. Also water has small solventeffect on the activation energies of debromination. The efficiency of debromination improves greatly in solvent mixturewith higher ratio of water in experiment probably because of more protons provided by more water for the corrosion anddebromination. Finally, the meta-bromine atoms are the most susceptible to be debrominated.

The annual and seasonal trends in pan evaporation in the lower Yellow River Basin based on quality-controlled data from 10 meteorological stations in 1961–2010 are analyzed. The causes for the changes in annual and seasonal pan evaporation are also discussed. The results suggest that, despite the 1.15°C increasing in annual mean surface air temperature over the past 50 years (0.23°C per decade), the annual pan evaporation has steadily declined by an average rate of −7.65 mm per year. By comparison, this change is greater than those previously reported in China. Significant decreasing trends in annual pan evaporation have been observed at almost all stations. As a whole, seasonal pan evaporation decreased significantly, especially in summer, whereas seasonal temperature increased significantly, except in summer. Thus, the pan evaporation paradox exists in the lower Yellow River Basin. The trend analysis of other meteorological factors indicates significant decrease in sunshine duration and wind speed, but no significant variations in precipitation and relative humidity at annual and seasonal time scales. By examining the relationship between precipitation and pan evaporation, it did not show a concurrent decrease in pan evaporation and increase in precipitation. The partial correlation analysis discovered that the primary cause of decrease in annual and seasonal pan evaporation is the decrease in wind speed. A further examination using a stepwise regression shows that decrease in wind speed and sunshine duration, and increase in mean temperature are likely to be the main meteorological factors affecting the annual and seasonal pan evaporation in the lower Yellow River Basin over the past 50 years.

Density functional theory and ab initio elongation-method-based calculations have been performed on the adsorptions of Si and C chains on unfaulted and faulted Si(111) surfaces and of Si chains on the Si(111)−OH surface. The C-chain adsorptions on the faulted and unfaulted Si(111) surfaces have almost the same geometries but different reaction energies. The C chain adsorbs more easily on the faulted Si(111) surface than on the unfaulted surface. The Si linkage atom is stabilized upon adsorption of a C chain on the unfaulted and faulted Si(111) surfaces. The band gap of a Si(111)−OH surface with an adsorbed Si chain and a Si−O linkage becomes narrower with respect to that of a clean Si(111)−OH surface. The local density of states of the Si substrate atom in the Si−O linkage shows that the electron peaks become more localized and stronger near the conduction band after the adsorption of the Si chain. Because of the replacement of the H atom bonded to the O atom by the adsorption of the Si chain, the energy range of the occupied molecular orbitals of the O linkage atom becomes broader near the band gap. The reaction energy of a C chain on the faulted Si(111) surface remains constant with C-chain length.

A new conservation theorem of the nonholonomic systems is studied. The conserved quantity is only constructed in terms of a general Lie group of transformation vector of the dynamical equations. Firstly, we establish the dynamical equations of the nonholonomic systems and the determining equations of Lie symmetry. Next, the theorem of non-Noether conserved quantity is deduced. Finally, we give an example to illustrate the application of the result.

The nonlinear optical properties, IR and Raman frequencies as well as NMR chemical shifts of two S6symmetrical C48N12azafullerene isomers Iand IIconformations were calculated and compared with those of C60at the B3LYP6-31G level of density functional theory. The second order hyperpolarizabilities were determined by means of ZINDOSOS. The static hyperpolarizabilities of C48N12are smaller than those of C60, whereas the DC-electric field induced second harmonic generation of IIis 58 larger than that of C60at the frequency of 1.1653 eV, suggesting that IIis a potential NLO candidate. In contrast to I, all five of the most intense IR and Raman frequencies of IIexceed 1000 cm−1. These differences, and those between the computed 13C NMR chemical shifts of Iand IIshould be useful to distinguish and to identify these two structural isomers.