Facile synthesis of metal-free organic dyes featuring a thienylethynyl spacer for dye sensitized solar cells

In this article, we report the facile synthesis of metal-free dyes 6 and 7, their solution-based optical and redox properties and their use as sensitizers in dye-sensitized solar cells (DSSCs). Our studies indicate that the addition of the second thiophene unit in dye 7, decreases the oxidation and reduction potential and consequently the band gap of the molecule compared to 6. Furthermore, increasing the length of the conjugated spacer also affects on the properties of the DSSCs, with dye 7 providing a higher power conversion efficiency compared to 6 (η = 4.49 versus 3.23%)

Side Channel Attacks and Countermeasures on Pairing Based Cryptosystems over Binary Fields

Pairings on elliptic curves have been used as cryptographic primitives for the development of new applications such as identity based schemes. For the practical applications, it is crucial to provide efficient and secure implementations of the pairings. There have been several works on efficient implementations of the pairings. However, the research for secure implementations of the pairings has not been thoroughly investigated. In this paper, we investigate vulnerability of the pairing used in some pairing based protocols against side channel attacks. We propose an efficient algorithm secure against such side channel attacks of the eta pairing using randomized projective coordinate systems for the pairing computation

Comparative study of two- and three-dimensional modeling on arc discharge phenomena inside a thermal plasma torch with hollow electrodes

A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has been developed by taking account of 3D arc current distribution and arc root rotation. The 3D simulation results apparently reveal that the 3D arc root attachment brings about the inherent 3D and turbulence nature of plasma fields inside the torch. It is also found that the constricted arc column near the vortex chamber plays an important role in heating and acceleration of injected arc gases by concentrating arc currents on the axis of the hollow electrodes. The inherent 3D nature of arc discharge is well preserved inside the cathode region, while these 3D features slowly diminish behind the vortex chamber where the turbulent flow begins to be developed in the anode region. Based on the present simulation results, it is noted that the mixing effects of the strong turbulent flow on the heat and mass transfer are mainly responsible for the gradual relaxation of the 3D structures of plasma fields into the 2D axisymmetric ones that eventually appear in the anode region near the torch exit. From a detailed comparison of the 3D results with the 2D ones, the arc root configuration seems to have a significant effect on the heat transfer to the electrode surfaces interacting with the turbulent plasma flow. That is, in the 2D simulation based on an axisymmetric stationary model, the turbulence phenomena are fairly underestimated and the amount of heat transferred to the cold anode wall is calculated to be smaller than that obtained in the 3D simulation. For the validation of the numerical simulations, calculated plasma temperatures and axial velocities are compared with experimentally measured ones, and the 3D simulation turns out to be more accurate than the 2D simulation as a result of a relatively precise description of the turbulent phenomena inside the torch using a more realistic model of arc root attachment. Finally, it is suggested that the 3D transient formulation is indeed required for describing the real arc discharge phenomena inside the torch, while the 2D stationary approach is sometimes useful for getting practical information about the time-averaged plasma characteristics outside the torch because of its simplicity and rapidness in computation.Ministry of Science and Technology in Kore

Delay-multiply-and-sum based synthetic aperture focusing in photoacoustic microscopy

We propose an improved version of a synthetic aperture focusing technique (SAFT) based on a delay-multiply-and-sum algorithm for acoustic-resolution photoacoustic microscopy (AR-PAM). In this method, the photoacoustic (PA) signals from multiple scan-lines are combinatorially coupled, multiplied, and then summed. This process can be considered a correlation operation of the PA signals in each scan-line, so the spatial coherent information between the PA signals can be efficiently extracted. By applying this method in conventional AR-PAM, lateral resolution and signal-to-noise ratio in out-of-focus regions are much improved compared with those estimated from the previously developed SAFT, respectively, thereby achieving the extension of the imaging focal region. Our phantom and in vivo imaging experiments prove the validity of our proposed method. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)open11413Nsciescopu

Thermotropic Liquid-Crystalline Properties of Viologens Containing 4-n-alkylbenzenesulfonates†

A series of viologens containing 4-n-alkylbenzenesulfonates were synthesized by the metathesis reaction of 4-n-alkylbenzenesulfonic acids or sodium 4-n-alkylbezenesulfonates with the respective viologen dibromide in alcohols. Their chemical structures were characterized by Fourier Transform Infrared, 1H and 13C Nuclear Magnetic Resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. They formed LC phases above their melting transitions and showed isotropic transitions. As expected, all the viologen salts had excellent stabilities in the temperature range of 278–295 °C as determined by thermogravimetric analysis

Thermotropic Liquid-Crystalline and Light-Emitting Properties of Bis(4-aalkoxyphenyl) Viologen Bis(triflimide) Salts

A series of bis(4-alkoxyphenyl) viologen bis(triflimide) salts with alkoxy chains of different lengths were synthesized by the metathesis reaction of respective bis(4-alkoxyphenyl) viologen dichloride salts, which were in turn prepared from the reaction of Zincke salt with the corresponding 4-n-alkoxyanilines, with lithium triflimide in methanol. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry, polarizing optical microscopy, and variable temperature X-ray diffraction. Salts with short length alkoxy chains had crystal-to-liquid transitions. Salts of intermediate length alkoxy chains showed both crystal-to-smectic A (SmA) transitions, Tms, and SmA-to-isotropic transitions, Tis. Those with longer length of alkoxy chains had relatively low Tms at which they formed the SmA phases that persisted up to the decomposition at high temperatures. As expected, all of them had excellent thermal stabilities in the temperature range of 330–370 °C. Their light-emitting properties in methanol were also included

A Study on the Application of the Safety Practice Index to Reduce Safety Accidents in the Manufacturing Industry

Human casualties caused by industrial accidents pose a serious threat to corporate management due to the continual strengthening of safety laws as well as changes in the public’s awareness of corporate social responsibility. Accordingly, companies are raising safety awareness among employees by regularly conducting on-site safety activities and training to prevent industrial accidents. However, the safety activities, education, and training of many companies are not carried out voluntarily or in practice by their employees, but mostly through formal implementation. To break away from these customary and passive behaviors and establish a mature safety culture, it is crucial to strengthen the execution capacity of safety management in the field; to this end, we plan to utilize the safety practice index (SPI). The safety practice index (SPI), which quantitatively represents the degree of safety practice, is necessary to increase the effectiveness of safety management for the purpose of preventing accidents. In this study, the correlation was verified by comparing the SPI calculated based on the 2018 and 2019 risk management and the safety activity results of manufacturer A with the reported safety accidents. It was also effective in improving the SPI and reducing safety accidents in 2020 by supplementing the weaknesses of the SPI in 2018 and 2019. According to the results of this study, SPI can be used as an effective indicator for safety accident prevention activities by supplementing weaknesses with strengths through strengthening leadership and safety policies, such as classifying and managing the safety management level of a specific period or department

GMASS: a novel measure for genome assembly structural similarity

Abstract Background Thanks to the recent advancements in next-generation sequencing (NGS) technologies, large amount of genomic data, which are short DNA sequences known as reads, has been accumulating. Diverse assemblers have been developed to generate high quality de novo assemblies using the NGS reads, but their output is very different because of algorithmic differences. However, there are not properly structured measures to show the similarity or difference in assemblies. Results We developed a new measure, called the GMASS score, for comparing two genome assemblies in terms of their structure. The GMASS score was developed based on the distribution pattern of the number and coverage of similar regions between a pair of assemblies. The new measure was able to show structural similarity between assemblies when evaluated by simulated assembly datasets. The application of the GMASS score to compare assemblies in recently published benchmark datasets showed the divergent performance of current assemblers as well as its ability to compare assemblies. Conclusion The GMASS score is a novel measure for representing structural similarity between two assemblies. It will contribute to the understanding of assembly output and developing de novo assemblers

A Study of K-ISMS Fault Analysis for Constructing Secure Internet of Things Service

Although Internet of Things (IoT) technologies and services are being developed rapidly worldwide, concerns of potential security threats such as privacy violation, information leak, and hacking are increasing as more various sensors are connected to the Internet. There is a need for the study of introducing risk management and existing security management standard (e.g., ISO27001) to ensure the stability and reliability of IoT services. K-ISMS is a representative certification system that evaluates the security management level of the enterprise in Korea and is possible to apply as a standardized process to enhance the security management of IoT services. However, there are growing concerns about the quality deterioration of the K-ISMS certification assessment these days because of internet security incidents occurring frequently in K-ISMS certified enterprises. Therefore, various researches are required to improve the accuracy and objectivity of the certification assessment. Since existing studies mainly focus on simple statistical analysis of the K-ISMS assessment results, analysis on the cause of certification assessment fault based on past data analysis is insufficient. As a method of managing the certification inspection quality, in this paper, we analyze the association among the fault items of the K-ISMS certification assessment results using association rule mining which involves identifying an association rule among items in the database