A Hierarchical Nanoparticle‐in‐Micropore Architecture for Enhanced Mechanosensitivity and Stretchability in Mechanochromic Electronic Skins

Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force‐responsive colorimetric sensors and soft robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a hierarchical nanoparticle‐in‐micropore (NP‐MP) architecture in porous mechanochromic polymers, which enhances the mechanosensitivity and stretchability of mechanochromic electronic skins (e‐skins), is reported. The hierarchical NP‐MP structure results in stress‐concentration‐induced mechanochemical activation of mechanophores, significantly improving the mechanochromic sensitivity to both tensile strain and normal force (critical tensile strain: 50% and normal force: 1 N). Furthermore, the porous mechanochromic composites exhibit a reversible mechanochromism under a strain of 250%. This architecture enables a dual‐mode mechanochromic e‐skin for detecting static/dynamic forces via mechanochromism and triboelectricity. The hierarchical NP‐MP architecture provides a general platform to develop mechanochromic composites with high sensitivity and stretchability.     

Perception of the upright in normal and schizophrenic subjects

To see the effects of a large angle of frame-tilt, movement of the rod in the clockwise direction, and the difference between the normal and schizophrenic subjects in the perception of the upright, a mixed design (subjects X angle X presentation X trial) was used. 24 normal and 24 schizophrenic subjects were tested in a darkroom with a rod-and-frame test. The results showed a small error with a clockwise movement of the rod, when the frame also was tilted clockwise, and no difference in perception of the upright between the normal and schizophrenic subjects.     

SWIFT—A new real time commit protocol

Although there are several factors contributing to the difficulty in meeting distributed real time transaction deadlines, data conflicts among transactions, especially in commitment phase, are the prime factor resulting in system performance degradation. Therefore, design of an efficient commit protocol is of great significance for distributed real time database systems (DRTDBS). Most of the existing commit protocols try to improve system performance by allowing a committing cohort to lend its data to an executing cohort, thus reducing data inaccessibility. These protocols block the borrower when it tries to send WORKDONE/PREPARED message [1, 6, 8, 9], thus increasing the transactions commit time. This paper first analyzes all kind of dependencies that may arise due to data access conflicts among executing-committing transactions when a committing cohort is allowed to lend its data to an executing cohort. It then proposes a static two-phase locking and high priority based, write-update type, ideal for fast and timeliness commit protocol i.e. SWIFT. In SWIFT, the execution phase of a cohort is divided into two parts, locking phase and processing phase and then, in place of WORKDONE message, WORKSTARTED message is sent just before the start of processing phase of the cohort. Further, the borrower is allowed to send WORKSTARTED message, if it is only commit dependent on other cohorts instead of being blocked as opposed to [1, 6, 8, 9]. This reduces the time needed for commit processing and is free from cascaded aborts. To ensure non-violation of ACID properties, checking of completion of processing and the removal of dependency of cohort are required before sending the YES-VOTE message. Simulation results show that SWIFT improves the system performance in comparison to earlier protocol. The performance of SWIFT is also analyzed for partial read-only optimization, which minimizes intersite message traffic, execute-commit conflicts and log writes consequently resulting in a better response time. The impact of permitting the cohorts of the same transaction to communicate with each other [5] on SWIFT has also been analyzed. Recommended by: Ahmed Elmagarmid     

Effect of elevated carbon dioxide and nitrogen management on rice milling qualities

Elevated atmospheric carbon dioxide (CO₂) concentration has a potential impact on the growth and yield of rice (Oryza sativa L.), but little is known on grain milling quality. A field experiment in open-top chamber (OTC) was conducted to assess the effect of elevated CO₂ under varying N management on brown rice, milled rice and head rice yield. The experiment was conducted during wet season (June–November) of the year 2011 and 2012 at Kharagpur, India, using a long-duration, high-yielding cultivar ‘Swarna Sub1,’ which was grown in open field and in OTCs of ambient and elevated CO₂ environment (25 % higher than ambient) with five different N management levels. The elevated CO₂ reduced the brown rice, milled rice and head rice percentage by 1.2, 1.4 and 14 %, respectively, as compared to ambient environment in OTC. Due to elevated CO₂, the reduction in processed yields were 9 and 4 % in brown/milled rice and 21 and 15 % in head rice under sole application of chemical fertilizer and integration of chemical and organic sources, respectively. The decrease in rice milling quality was associated with increasing canopy temperature (+0.8 °C) during grain-filling stage under elevated CO₂ environment. The elevated CO₂ has a substantial adverse impact on grain milling quality, and to some extent, this can be compensated through proper N management.     

Long-distance axial trapping with Laguerre-Gaussian beams

We show that the axial spread of the focal volume of a tightly focused beam propagating through a glass-water interface is much reduced for Laguerre-Gaussian (LG) modes as compared to the TEM(00) mode. Therefore, use of the LG beam helps in achieving a significant improvement of the axial trapping range in optical tweezers. We demonstrate the use of LG modes to manipulate biological cells from the bottom layer of the medium to the top surface layer. Exposure of the cells to a higher oxygen concentration at the surface layer is used for estimation of the intramembrane oxygen diffusion rate.     

Optical bifunctionality of europium-complexed luminescent graphene nanosheets

Graphene is an intriguing two-dimensional material, which could be modified for achieving tunable properties with many applications. Photoluminescence of graphene due to plasmonic emission is well-known, however, attempts to develop strong luminescent graphene have been difficult. Synthesis of a graphene-based material with a dual optical functionality, namely quenching the fluorescence of organic dyes while maintaining its own self-luminescence, is an interesting and challenging proposition. Here, we demonstrate this optical bifunctionality in a lattice-modified luminescent graphene, where europium(III) cations are complexed with graphene through oxygen functionalities. After excitation at 314 nm, a hypersensitive red emission is observed at 614 and 618 nm showing the complexation of europium(III) with graphene. We demonstrate dual functionality of this graphene by the quenching of luminescence of Rhodamine-B while displaying its own hypersensitive red emission. The decay lifetime observed through the time-resolved spectroscopy confirms its potential for applications in biosensing as well as optoelectronics.     

Rapid analysis of scattering from periodic dielectric structures using accelerated Cartesian expansions

The analysis of fields in periodic dielectric structures arise in numerous applications of recent interest, ranging from photonic bandgap structures and plasmonically active nanostructures to metamaterials. To achieve an accurate representation of the fields in these structures using numerical methods, dense spatial discretization is required. This, in turn, affects the cost of analysis, particularly for integral-equation-based methods, for which traditional iterative methods require O(N2) operations, N being the number of spatial degrees of freedom. In this paper, we introduce a method for the rapid solution of volumetric electric field integral equations used in the analysis of doubly periodic dielectric structures. The crux of our method is the accelerated Cartesian expansion algorithm, which is used to evaluate the requisite potentials in O(N) cost. Results are provided that corroborate our claims of acceleration without compromising accuracy, as well as the application of our method to a number of compelling photonics applications.     

Determination of optimal AGV fleet size for an FMS

The required number of AGVs necessary to perform a given level of material handling task in an FMS environment is determined using analytical and simulation modelling. The analytical method involves consideration of load handling time, empty travel time, and waiting and blocking time. Load handling time is computed from given system parameters. Determination of empty vehicle travel is difficult due to the inherent randomness of an FMS. Several research studies for this purpose are discussed and a new model is proposed. It entails formulation of a mixed integer programme with an objective of minimizing empty trips. The constraints are in the form of upper and lower bounds placed on the total number of empty trips starting from or ending at a load transfer station. The phenomena of vehicle waiting and blocking are also discussed. The cumulative impact of these three time estimates are then translated into an initial estimate of AGV fleet size as predicted by individual models. The method is applied to an illustrative example. Finally, simulation methodology is used to validate the initial estimates of fleet size. The results indicate that the different models either under-estimate or over-estimate the actual number of vehicles required in the system. The proposed model, though under-estimates the minimum AGV requirement, yet provides results which are close to the simulation results. Hence, it can be used as an analytical tool prior to the simulation phase of AGVS design.     

How manufacturing processes affect the level of pesticide residues in tea

Tea (both green and black) is consumed throughout the world, both for pleasure and therapeutic purposes. Most people will be unaware of their involuntary exposure to residues of pesticides lingering in processed tea and so possibly transferring into infusions of tea. The purpose of this work was to study the effect of green tea and orthodox black tea manufacturing processes on the fate of pesticides sprayed onto tea bushes (Camellia sinensis). The fates of residues of dimethoate, quinalphos, dicofol and deltamethrin in these two different types of tea manufacturing processes were compared. For black tea, the manufacturing process involves leaf harvesting, withering, rolling, fermentation and drying; and for green tea, leaf harvesting, microwave heating, rolling and drying. The two processes resulted in the same concentration factor of plant material into the dried commodity, while the decreases in residue levels were different for different pesticides. Initial microwave heating and dehydration in the green tea manufacturing process resulted in greater loss of pesticide residues than did withering and dehydration in black tea; no significant reduction in residue level resulted from the rolling and fermentation steps in black tea. Residue levels in both green and black teas were reduced during final drying. Copyright © 2004 Society of Chemical Industry