Examination of the role of oxygen in the photografting of methacrylic acid on a polyethylene film with a mixed solvent consisting of water and organic solvents

The photografting of methacrylic acid (MAA) on a linear low‐density polyethylene film (thickness = 30 μm) under air and nitrogen atmospheres was investigated at 60°C in mixed solvents consisting of water and an organic solvent, with xanthone as a photoinitiator. The organic solvents used were acetone, methanol, tetrahydrofuran, and dioxane. A maximum percentage of grafting occurred at a certain concentration of the organic solvent in the mixed solvent. This was observed for the systems under both air and nitrogen. The grafting reaction under air exhibited an induction period, but the rate of grafting after the period was greater than that under nitrogen. The formation of poly(ethylene peroxide)s by photoirradiation seemed to be a factor for the accelerated photografting under air. On the basis of attenuated total reflection infrared spectroscopy and scanning electron microscopy of the grafted film, the MAA‐grafted chains of the sample prepared under air tended to penetrate more deeply inside the film than those of the sample prepared under nitrogen. The resulting grafted films exhibited a pH‐responsive character: the grafted films shrank in an acidic medium but swelled in alkaline medium. This was evaluated from measurements of dimensional changes in the grafted films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 992–998, 2003     

Combination of Hargreaves method and linear regression as a new method to estimate solar radiation in Perlis, Northern Malaysia

The best way to obtain the solar radiation data of a particular place of interest (POI) is to measure at the specific site continuously and accurately over the long term. However, due to financial, maintenance, calibration requirement of the measuring equipment or institutional limitations, these data are absent, incomplete or inaccessible in most areas of the world. Based on meteorological data from Chuping Station, Perlis which is at Northern Malaysia, there were several missing data of solar radiation for the year 2007 and 2008. This paper presents a new method to estimate the solar radiation which is a combination of Hargreaves method and linear regression. Normally, both regression coefficients, a and b of the linear regression are found based on the measured data, but using the proposed method, both regression coefficients based on the Hargreaves method with the correlated parameter, x is the difference of daily temperature. This paper also presents the basic knowledge of Hargreaves method before the proposed method is implemented. As validation, those solar radiation data that are measured by Chuping Station for the year 2006 and by Electrical Energy and Industrial Electronic System (EEIES) Cluster Station for the month of March–June 2011 and their estimated solar radiation data are compared and analyzed using coefficient of residual mass (CRM), root mean squared error (RMSE), Nash–Sutcliffe equation (NSE) and percentage error (e). The statistical analysis of the average monthly measured solar radiation data for the past 26 years (1979–2006) is compared with the estimated solar radiation data for 3 years (2006–2008). The proposed method result shows that the value of CRM is closer to zero which indicates that the proposed method is perfectly estimated, the values of RMSE are low value, this indicates that the method performs well, the value of NSE is closer to 1 which indicates that the estimated solar radiation match perfectly with the measured data taken for the past 26 years, the value of e is closer to zero which indicates that the proposed method is acceptable and applicable.     

Dynamic Data Driven Simulations in Stochastic Environments

To improve the predictions in dynamic data driven simulations (DDDAS) for subsurface problems, we propose the permeability update based on observed measurements. Based on measurement errors and a priori information about the permeability field, such as covariance of permeability field and its values at the measurement locations, the permeability field is sampled. This sampling problem is highly nonlinear and Markov chain Monte Carlo (MCMC) method is used. We show that using the sampled realizations of the permeability field, the predictions can be significantly improved and the uncertainties can be assessed for this highly nonlinear problem.     

A Fully Autonomous Microrobotic Endoscopy System

In this paper, design of an autonomous microrobotic endoscopy system is presented. The proposed microrobotic endoscope is a vision-guided device, developed to facilitate navigation inside a human colon. The design of the entire system is divided into three areas viz. design of a microrobotic carrier, path planning and guidance, and an off-board control system. A microrobotic design based on pneumatic mechanisms to achieve locomotion and steering is explained. General mathematical analysis governing the differential steering of the robotic tip is also described. The path planning of the microrobot is carried out based on the sensory fusion utilising the quantitative parameters from the captured images and the tactile sensors. A real-time image segmentation scheme is described for extracting the lumen from endoscopic images. An off-board control system to control the directional movements of the microrobot is also explained. The proposed endoscopy system was tested with physical models and animal colons and the experimental observations are presented.     

采用剪切弯曲三角杆的对称冷弯型钢-混凝土组合梁的大比例试验

对对称冷弯型钢-混凝土组合梁进行静力受弯试验,介绍了基于剪切弯曲杆改进的剪切弯曲三角杆。冷弯型钢构件比热轧构件更薄,不允许焊接栓钉剪力连接件,剪切弯曲三角杆能解决这一问题。将两个冷弯型钢槽的背靠背连接成对称构件,它在静力作用下具有足够的强度和刚度。通过剪切弯曲三角杆的抗剪方程计算的抗弯承载值与试验数据很吻合。     

Large-scale test of symmetric cold-formed steel (CFS)-concrete composite beams with BTTST enhancement

A new connection device, based on bent-up tab shear transfer enhancement called bent-up triangular tab shear transfer (BTTST), has been studied through a symmetric cold-formed steel (CFS)-concrete composite beam subjected to a static bending test. BTTST provides an alternative connector system unique to CFS where CFS sections are usually thinner than hot-rolled sections and welding of headed-stud shear connectors is inapplicable. Coupled with the back-to-back arrangement of two CFS channels where symmetricity of the built-up section is restored, the resulting composite floor system has been proven to possess adequate strength and stiffness properties under static loads. The work has shown that the predicted values of the flexural capacities calculated using a new equation of shear capacity of BTTST agrees reasonably well with the experimental values.     

Locomotion techniques for robotic colonoscopy.

Colonoscopy has become a routine procedure in many hospitals all over the world for colon cancer diagnosis. This review article discusses the work done by researchers in the quest to automate the colonoscopy procedure. In vitro and in vivo experimentation have been carried out to prove the possibilities of a robot crawling along a patient's colon, treating polyps as they are encountered. Locomotion is an essential part of robotic colonoscopy. The robot must be able to propel itself from the anus right up to the cecum without damaging the colon walls. The challenge is to design a robust locomotion technique that is able to advance through the stretchable, slippery, and mobile colon, which is always in its collapsed stage, in three-dimensional orientation. The authors believe that in the future, conventional colonoscopy will be revolutionized, giving way to robotics to assist doctors in colonoscope manipulation and performing therapeutic procedures and leaving doctors to concentrate on the diagnostic aspect of the procedure, which would encourage mass screening as more patients can be evaluated per session.     

On a simple triangular reissner/mindlin plate element based on incompatible modes and discrete constraints

In this paper the formulation of a new triangular element based on the Reissner/Mindlin plate theory is presented. The element has three nodes and three d.o.f. per node only. It is based on constant bending modes plus incompatible energy orthogonal higher order bending modes. The transverse shear effects are represented using the moment equilibrium and the constitutive equations. Discrete (collocation) shear constraints are considered on each side to relate the kinematical and the independent shear strains. The element has a proper rank, is completely locking free, passes all constant patch-tests exactly. The detailed numerical evaluation shows that the element, called DST-BK, is a robust and high-performance element for thick and thin plates.     

The nuclear actin-related protein Act3p/Arp4p is involved in the dynamics of chromatin-modulating complexes

Chromatin remodelling and histone-modifying complexes govern the modulation of chromatin structure. While components of these complexes are diverse, nuclear actin-related proteins (Arps) have been repeatedly found in these complexes from yeast to mammals. In most cases, Arps are required for functioning of the complexes, but the molecular mechanisms of nuclear Arps have as yet been largely unknown. The Arps and actin, sharing a common ancestor, are supposed to be highly similar in the three-dimensional structure of their core regions, including the ATP-binding pocket. The Arp Act3p/Arp4p of Saccharomyces cerevisiae exists within the nucleus, partly as a component of several high molecular mass complexes, including the NuA4 histone acetyltransferase (HAT) complex, and partly as uncomplexed molecules. We observed that mutations in the putative ATP-binding pocket of Act3p/Arp4p increased its concentration in the high molecular mass complexes and, conversely, that an excess of ATP or ATPgammaS led to the release of wild-type Act3p/Arp4p from the complexes. These results suggest a requirement of ATP binding by Act3p/Arp4p for its dissociation from the complexes. In accordance, a mutation in the putative ATP binding site of Act3p/Arp4p inhibited the conversion of the NuA4 complex into the smaller piccoloNuA4, which does not contain Act3p/Arp4p and exhibits HAT activity distinct from that of NuA4. Although the in vitro binding activity of ATP by recombinant Act3p/Arp4p was found to be rather weak, our observations, taken together, suggest that the ATP-binding pocket of Act3p/Arp4p is involved in the function of chromatin modulating complexes by regulating their dynamics.