Improvement in Transdermal Bioavailability of Nitroglycerin by Formulation Design

Controlled skin permeation kinetics of nitroglycerin delivered by the three once-a-day transdermal therapeutic systems was recently evaluated and compared using the freshly excised hairless mouse abdominal skin mounted in a finite-dosing Frantz diffusion cell assembly. The kinetics of skin permeation from the conventional ointment formulation was also studied using the same in vitro skin permeation system.

Six experimental formulations of nitroglycerin were developed, aiming to enhance the permeation rate of nitroglycerin through intact skin. The kinetics of skin permeation of nitroglycerin from these experimental formulations was also investigated, using the same in vitro skin permeation system, and compared to the conventional ointment formulation as well as the newly marketed once-a-day transdermal therapeutic systems. Results indicated that the rates of skin permeation can be greatly improved by proper formulation design.     

Carrier–Phonon Interaction Induced Large Negative Thermal-Optic Coefficient at Near Band Edge of Quasi-2D (PEA)2PbBr4 Perovskite

The soft and polar nature of quasi-2D (PEA)₂PbBr₄ perovskite, and robust photo-generated excitons lead exciton-polaritons and exciton-polarons as the important phenomena near the band edge for application in the lighting aspect. In this work, a convenient methodology is proposed based on the polariton resonant modes in temperature-dependent (77 K to RT) spectroscopy, and investigate the effect of these quasi-particles on refractive index dispersion. The large binding energy (≈335 meV) of quasi-2D excitons is obtained by the reflectance measurements at 77 K. Stable exciton-polaritons and exciton-polarons are confirmed by energy dispersions and the observation of self-trapped exciton-polaron state, respectively. Furthermore, the large negative thermal-optic coefficient due to damping effect of exciton-phonon scattering is observed. The phenomenon is opposite to those observed in conventional semiconductors (e.g., Si, Ge, GaN, AlN, GaAs, AlAs, and ZnO etc.). The observed stable negative thermal-optic coefficients from 160 K to RT indicate that the quasi-2D perovskite can be used as a phase compensator for conventional semiconductor materials.     

Why the mind may not be modular

Fodor argued that in contrast to input systems which are informationally encapsulated, general intelligence is unencapsulated and hence non-modular; for this reason, he suggested, prospects for understanding it are not bright. It is argued that an additional property, primitive functionality, is required for non-modularity. A functionally primitive computational model for quantifier scoping, limited to some scoping influences, is then motivated, and an implementation described. It is argued that only such a model can be faithful to intuitive scope preferences. But it is also argued that an extended model which includes all scoping influences is a hopeless prospect from a developmental perspective. Fodor's views are concluded to have some independent support: quantifier scoping is a mental ability parasitic on general intelligence that is non-modular though in a revised sense, warranting pessimism about our ability of model it.     

Combining scanning tunneling microscopy and synchrotron radiation for high-resolution imaging and spectroscopy with chemical, electronic, and magnetic contrast

The combination of high-brilliance synchrotron radiation with scanning tunneling microscopy opens the path to high-resolution imaging with chemical, electronic, and magnetic contrast. Here, the design and experimental results of an in-situ synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system are presented. The system is designed to allow monochromatic synchrotron radiation to enter the chamber, illuminating the sample with x-ray radiation, while an insulator-coated tip (metallic tip apex open for tunneling, electron collection) is scanned over the surface. A unique feature of the SXSTM is the STM mount assembly, designed with a two free-flex pivot, providing an angular degree of freedom for the alignment of the tip and sample with respect to the incoming x-ray beam. The system designed successfully demonstrates the ability to resolve atomic-scale corrugations. In addition, experiments with synchrotron x-ray radiation validate the SXSTM system as an accurate analysis technique for the study of local magnetic and chemical properties on sample surfaces. The SXSTM system's capabilities have the potential to broaden and deepen the general understanding of surface phenomena by adding elemental contrast to the high-resolution of STM.     

Optimizing bus services with variable directional and temporal demand using genetic algorithm

As a major mode choice of commuters for daily travel, bus transit plays an important role in many urban and metropolitan areas. This work proposes a mathematical model to optimize bus service by minimizing total cost and considering a temporally and directionally variable demand. An integrated bus service, consisting of all-stop and stop-skipping services is proposed and optimized subject to directional frequency conservation, capacity and operable fleet size constraints. Since the research problem is a combinatorial optimization problem, a genetic algorithm is developed to search for the optimal result in a large solution space. The model was successfully implemented on a bus transit route in the City of Chengdu, China, and the optimal solution was proved to be better than the original operation in terms of total cost. The sensitivity of model parameters to some key attributes/variables is analyzed and discussed to explore further the potential of accruing additional benefits or avoiding some of the drawbacks of stop-skipping services.     

Cost minimization in placing service chains for virtualized network functions

Network function virtualization (NFV) places network functions onto the virtual machines (VMs) of physical machines (PMs) located in data centers. In practice, a data flow may pass through multiple network functions, which collectively form a service chain across multiple VMs residing on the same or different PMs. Given a set of service chains, network operators have two options for placing them: (a) minimizing the number of VMs and PMs so as to reduce the server rental cost or (b) placing VMs running network functions belonging to the same service chain on the same or nearby PMs so as to reduce the network delay. In determining the optimal service chain placement, operators face the problem of minimizing the server cost while still satisfying the end‐to‐end delay constraint. The present study proposes an optimization model to solve this problem using a nonlinear programming (NLP) approach. The proposed model is used to explore various operational problems in the service chain placement field. The results suggest that the optimal cost ratio for PMs with high, hybrid, and low capacity, respectively, is equal to 4:2:1. Meanwhile, the maximum operating utilization rate should be limited to 55% in order to minimize the rental cost. Regarding quality of service (QoS) relaxation, the server cost reduces by 20%, 30%, and 32% as the end‐to‐end delay constraint is relaxed from 40 to 60, 80, and 100 ms, respectively. For the server location, the cost decreases by 25% when the high‐capacity PMs are decentralized rather than centralized. Finally, the cost reduces by 40% as the repetition rate in the service chain increases from 0 to 2. A heuristic algorithm, designated as common sub chain placement first (CPF), is proposed to solve the service chain placement problem for large‐scale problems (eg, 256 PMs). It is shown that the proposed algorithm reduces the solution time by up to 86% compared with the NLP optimization model, with an accuracy reduction of just 8%.     

Synergistic Reinforcement of Built‐In Electric Fields for Highly Efficient and Stable Perovskite Photovoltaics

Perovskite solar cells (PSCs) have received great attention due to their outstanding performance and their low processing costs. To boost their performance, one approach is to reinforce the built‐in electric field (BEF) to promote oriented carrier transport. The BEF is maximized by reinforcing the work function difference between cathode and anode (Δμ₁) and increasing the work function difference between lower and upper surfaces of perovskite film (Δμ₂) via introduction of electric dipole molecules, denoted as PTFCN and CF3BACl. The synergistic reinforcement of BEF improves charge transport and collection, and realizes markedly high photovoltaic performances with the best power conversion efficiency (PCE) up to 21.5%, a growth of 15.6% as compared to the control device, which is higher than the superposition of improvements achieved by either raising Δμ₁ or Δμ₂. Importantly, dual‐functional CF3BACl not only supplies dipole effect for tuning the surface potential of perovskite but offers hydrophobic trifluoride group toward the long‐term stable unencapsulated PSCs retaining more than 95% PCE after storing 2000 h under ambient conditions. This work demonstrates the synergistic effect of Δμ₁ and Δμ₂, providing an effective strategy for the further development of PSC in terms of photovoltaic conversion and stability.     

Learner readiness for online learning: Scale development and student perceptions

The purpose of this study was to develop and validate a multidimensional instrument for college students’ readiness for online learning. Through a confirmatory factor analysis, the Online Learning Readiness Scale (OLRS) was validated in five dimensions: self-directed learning, motivation for learning, computer/Internet self-efficacy, learner control, and online communication self-efficacy. Research data gathered from 1051 college students in five online courses in Taiwan revealed that students’ levels of readiness were high in computer/Internet self-efficacy, motivation for learning, and online communication self-efficacy and were low in learner control and self-directed learning. This study found that gender made no statistical differences in the five OLRS dimensions, but that higher grade (junior and senior) students exhibited significantly greater readiness in the dimensions of self-directed learning, online communication self-efficacy, motivation for learning, and learner control than did lower grade (freshman and sophomore) students.     

A decision support system for engineering design based on an enhanced fuzzy MCDM approach

Design concept is an important wealth-creating activity in companies and infrastructure. However, the process of designing is very complex. Besides, the information required during the conceptual stage is incomplete, imprecise, and fuzzy. Hence, fuzzy set theory should be used to handle linguistic problem at this stage. This paper presents a fuzzy integrated approach to assess the performance of design concepts. And those criteria rating, relative weights and performance levels are captured by fuzzy numbers, and the overall performance of each alternative is calculated through an enhanced fuzzy weighted average (FWA) approach. A practical numerical example is provided to demonstrate the usefulness of this study. In addition, this paper, in order to make computing and ranking results easier to increase the recruiting productivity, develops a computer-based decision support system to help make decisions more efficiently.