Dow Chemical (South Korea)

A number of Angelica species have been used in traditional systems of medicine to treat many ailments. Especially, essential oils (EOs) from the Angelica species have been used for the treatment of various health problems, including malaria, gynecological diseases, fever, anemia, and arthritis. EOs are complex mixtures of low molecular weight compounds, especially terpenoids and their oxygenated compounds. These components deliver specific fragrance and biological properties to essential oils. In this review, we summarized the chemical composition and biological activities of EOs from different species of Angelica. For this purpose, a literature search was carried out to obtain information about the EOs of Angelica species and their bioactivities from electronic databases such as PubMed, Science Direct, Wiley, Springer, ACS, Google, and other journal publications. There has been a lot of variation in the EO composition among different Angelica species. EOs from Angelica species were reported for different kinds of biological activities, such as antioxidant, anti-inflammatory, antimicrobial, immunotoxic, and insecticidal activities. The present review is an attempt to consolidate the available data for different Angelica species on the basis of major constituents in the EOs and their biological activities.

Medium to low density thermoplastic nanofoams have previously been produced using nanoparticles as nucleating center. Here we show that by designing the molecular structure of the polymer matrix to achieve high CO 2 solubility while controlling the glass transition temperature, it is possible to produce nanofoams with cell nucleation densities as high as 10 16 /cm 3 without introducing nucleation aids. This was achieved by maximizing foam expansion without uncontrolled cell ripening for a series of acrylic copolymers, which were foamed under a set of standard conditions. To predict the role of foaming conditions on foam characteristics, a theoretical foaming model was built to simulate cell nucleation, growth and foam stabilization. Experimental or predicted properties of the polymer/carbon dioxide mixture were used as inputs. Despite simplifying assumptions, such as the use of classical nucleation equations, the semi-quantitative model provides insight into the foam expansion behavior and validates experimental observations.

Epilepsy is one of the most serious chronical neurological disorders, affecting more than 50 million people worldwide. It can be defined as a spectrum disorder, and patients with epilepsy possess abnormalities in cognitive functions. A number of factors can cause cognitive dysfunctions in epileptic syndromes, including etiology, the age of onset, type of seizure and severity, duration, and antiepileptic drugs. Event-related potentials (ERPs) are very useful clinical and research instruments to evaluate cognitive function in patients with neuropsychiatry disorders. Event-related potentials directly reflect cortical neuronal activity and provide a particular level of temporal resolution. Among various ERP components, the P300 is the most important component for assessing cognitive processes such as attention, working memory, and concentration. Numerous studies have reported the abnormalities in amplitude or latency of P300 component of ERP in epileptic patients, and these abnormalities are indicative of cognitive dysfunction. Therefore, the purpose of this review is to consolidate the existing literature in connection with the use of P300 in epileptic patients.

Organic light-emitting diode (OLED) displays have been an active and intense area of research for well over a decade and have now reached commercial success for displays from cell phones to large format televisions. A more thorough understanding of the many different potential degradation modes which cause OLED device failure will be necessary to develop the next generation of OLED materials, improve device lifetime, and to ultimately improve the cost vs performance ratio. Each of the different organic layers in an OLED device can be susceptible to unique decomposition pathways, however stability toward excitons is critical for emissive layer (EML) materials as well as any layer near the recombination zone. This study will specifically focus on degradation modes within the hole transport layer (HTL) with the goal being to identify the general decomposition paths occurring in an operating device and use this information to design new derivatives which can block these pathways. Through post-mortem analyses of several aged OLED devices, an apparently common intramolecular cyclization pathway has been identified that was not previously reported for arylamine-containing HTL materials and that operates parallel to but faster than the previously described fragmentation pathways.

An eleven-step synthesis of (±)-spongiolactone from 1,3-cyclohexanedione is reported that relies on a diastereoselective, nucleophile-catalyzed aldol lactonization (NCAL) process with an advanced ketoacid intermediate that installed the anticipated β-lactone pharmacophore of the natural product. In addition, a stereoselective cyclohexenyl zinc addition to a substituted cyclohexanone simultaneously installed two fully substituted vicinal stereocenters. The reported synthesis enabled preliminary structure-activity studies that revealed a regio- and stereoisomeric derivative of spongiolactone with greater antiproliferative activity towards a leukemia (K562) cell line. Furthermore, unusual antiproliferative selectivity of these spongiolactone derivatives toward the K562 cell line was observed with no inhibition of the breast, liver, and lung cancer cell lines tested.

Abstract High strength aluminum alloys of type AA2014 are used in aerospace applications. This alloy is considered unweldable using fusion welding processes. Friction stir welding being a solid state process has been proved to be a suitable process for obtaining sound welds of these materials. In the current study, 8 mm thick rolled AA2014-T651 aluminum alloy plates were joined using friction stir welding. The corrosion behavior of base material and friction stir welds was investigated using the salt fog test (ASTM B117). The corrosion resistance of the welds and parent material in the basic solution was found to be better than that in acidic and neutral solutions. It was also found that the corrosion rate increases with increase in time of exposure. It has been observed that corrosion attack is greater in the weld region than in the parent material and within the weld, heat affected zone has been found to be more susceptible to corrosion compared to the weld nugget and thermomechanically affected zone regions. Transmission electron microscopy studies revealed coarser precipitates and precipitate-free zones in the heat affected zone which are concluded to be the reasons for more susceptibility to corrosion.

Geosmin and 2-methylisoborneol, molecules with the same odor characteristics, are mainly responsible for the smell of soil and cause odor problems worldwide in drinking water supplies. However, the effect of these odor molecules on human brain function is still unclear. The present investigation aimed to evaluate the effect of inhalation of geosmin and 2-methylisoborneol on human electroencephalographic (EEG) activity in order to understand whether their action on brain wave activity is the same or different. A total of 20 healthy volunteers (10 women and 10 men) were selected to determine the EEG power spectrum changes. The EEG data were recorded from 32 channels according to the International 10–20 system and 25 EEG power spectrum indices were analyzed. The inhalation of geosmin and 2-methylisoborneol exhibited different EEG activity by producing changes in different EEG indicators as well as brain regions. In both genders, significant changes in EEG power spectra were observed during the inhalation of geosmin when compared with 2-methylisoborneol. Absolute waves such as beta, fast alpha, low beta, high beta, and gamma significantly decreased, particularly in the centro-parietal (Cp6) region, due to the exposure to geosmin. According to gender variation, geosmin produced significant changes in the absolute low beta and high beta waves at the Cp6 region in women. In the case of 2-methylisoborneol, a significant increase in absolute alpha and absolute fast alpha activity was observed at the F8 region in men. However, there were no significant changes in absolute waves for men and women during the inhalation of geosmin and 2-methylisoborneol. Although both components are responsible for soil smell, they exhibit significantly different EEG activity according to gender.

Abstract The sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a major pest on greenhouse crops including sweet pepper ( Capsicum annuum L.), which is one of the leading greenhouse crops in South Korea. Synthetic insecticides, especially the neonicotinoids, have been used to conventionally control this pest. There have been continuous efforts to develop plant‐derived compounds as insecticides, deterrents, and repellents to reduce spraying synthetic insecticides. To develop new plant‐extract insecticides, we investigated the insecticidal effects of Perilla sp. ( Perilla frutescens var. crispa ) extract on B. tabaci in laboratory conditions. The Perilla sp. extract induced 90 % mortality within one hour, but phytotoxicity symptoms on sweet pepper leaves were also observed. We monitored the population change and spatial distribution of adult B. tabaci in an experimental sweet pepper greenhouse using yellow sticky traps, and analyzed distribution patterns by spatial analysis with distance indices (SADIE). Based on monitoring data and SADIE analysis, we concluded that B. tabaci aggregated near the greenhouse entrances, and it showed aggregation and association pattern as time passed. Therefore, we recommend spraying Perilla sp. extract near the entrances or wild host before the pest population penetrates. It will be one of the alternative pest management strategies to reduce B. tabaci population with fewer negative effects from chemical insecticide. Further study is required to reduce the phytotoxicity symptoms from Perilla sp. extract spray and insecticidal effect should be evaluated under field conditions.

Transferring knowledge from experts to apprentices is critical for sustaining a company’s competitive advantage. Further, existing literature indicates that employees in the Millennial (Y) generation and Generation Z prefer collaboration in the work environment. To address such needs, this research study aims to analyze the factors that enable knowledge collaboration among apprentices and experts in the practice of engineering. Survey data collected from 138 apprentices in the practice of engineering revealed that apprentices are more likely to collaborate with experts within their companies when they can trust the experts and perceive support for collaboration from senior management. This research adds to the body of knowledge by explicitly addressing apprentices’ trust, senior management support, intrinsic motivation, and knowledge collaboration with experts. Engineering managers can use this article to utilize trust, support from senior management, and employee’s intrinsic motivation to increase knowledge collaboration success among engineering experts and apprentices.

The present study aimed to evaluate the phytotoxic potential of essential oils. For this purpose, 18 essential oil samples extracted from Korean plants and 64 commercial essential oils were screened for their phytotoxic potential against the seedling growth of Brassica napus L. (rapeseed). Among the 82 samples, 11 commercial oils (cinnamon, citronella, clove, cumin seed, geranium, jasmine, lemongrass, palmarosa, pimento, rose otto and spearmint) strongly inhibited the seedling growth with <TEX>$GR_{50}$</TEX> value < <TEX>$150{\mu}g\;mL^{-1}$</TEX>. Major components from these effective essential oils were identified by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). GC-MS analyses revealed that the effective samples mainly consist of benzyl benzoate, carvone, citral, citronellol, eugenol, geraniol, D-limonene and terpinene. Subsequently, bioactivity of these individual components was evaluated against the seedling growth of B. napus, Echinochloa crus-galli and Aeschynomene indica. The components from different chemical groups exhibited different potency in inhibiting the seedling growth with varied <TEX>$GR_{50}$</TEX> values ranged from <TEX>$29{\mu}g\;mL^{-1}$</TEX> to > <TEX>$1000{\mu}g\;mL^{-1}$</TEX>. In the greenhouse experiment, citral and geraniol completely suppressed the growth of all the tested 10 plants at <TEX>$100kg\;ha^{-1}$</TEX>. In conclusion, the individual essential oil components geraniol and citral could be used as natural herbicides for weed management.

본 연구의 목적은 국내의 대표적인 침엽수인 소나무, 잣나무, 낙엽송, 분비나무로부터 추출된 정유의 제초활성을 이해하는데 있었다. 소나무, 잣나무, 낙엽송, 분비나무 정유의 기내 종자발아 제초활성 검정 결과, 유채에 대한 <TEX>$GR_{50}$</TEX> 값은 각각 0, 4,766, 1,865, <TEX>$5,934{\mu}g\;ml^{-1}$</TEX>으로 소나무를 제외하고는 제초활성을 나타내었다. 온실조건에서 소나무, 잣나무, 낙엽송, 분비나무 정유 10%를 5종의 화본과 잡초와 5종의 광엽잡초에 처리한 결과 도꼬마리를 제외하고는 24시간 내에 완전 고사되었으며, 처리 식물의 부위는 타는 듯한 화염상 증상을 나타내었고, 처리 3일 이후에는 신초가 재생하여 4종 식물 정유는 속효성, 비선택성, 비이행성 특성을 나타내었다. 소나무, 잣나무, 낙엽송, 분비나무의 정유를 GC-MS로 분석한 결과 각각 16종, 25종, 25종, 16종의 유기화합물이 검출되었으며, 이들 정유에는 탄화수소, 알코올, 케톤, 에스테르가 공통적으로 함유되어 있었다. 그리고 정유 4종의 주 화합물은 3-carene, bornyl acetate, camphene, limonene, <TEX>${\alpha}$</TEX>-pinene, <TEX>${\beta}$</TEX>-pinene, <TEX>${\beta}$</TEX>-phellandrene 이었다. The objective of this research was to understand herbicidal activity of essential oils isolated from leaves of pine (Pinus densiflora), nut pine (Pinus koraiensis), larch (Larix kaempferi) and khingan fir (Abies nephrolepsis) in Korea. In a seed bioassay, essential oils of nut pine, larch and khingan fir inhibited the growth of rapeseed (Brassica napus) seedlings by 50% at 4,766, 1,865, <TEX>$5,934{\mu}g\;ml^{-1}$</TEX>, respectively, however, that of pine did not show any herbicidal effect. In a green house experiment, fall panicum, Southern crabgrass, sorghum, barnyardgrass, quackgrass, black nightshade, Indian jointvetch, velvet leaf, and Japanese morningglory were controlled in 24 hours by the foliar application of 10% essential oils from pine, nut pine, larch and khingan fir. The treated plant parts showed burndown effect, however, new shoots appeared 3 days after treatment. Results of GC-MS analysis showed that essential oils from pine, nut pine, larch and khingan fir contained 16, 25, 25, and 16 compounds, respectively, with hydrocarbons, alcohols, ketones, and esters. The major compounds of the essential oils were 3-carene, bornyl acetate, camphene, limonene, <TEX>${\alpha}$</TEX>-pinene, <TEX>${\beta}$</TEX>-pinene and <TEX>${\beta}$</TEX>-phellandrene.

The quality of dielectric elastomer (DE) films is a key factor affecting the reliability of DE actuators. Reported here is the effect of the number of micron-sized defects on dielectric strength (DS) for poly(dimethylsiloxane) (PDMS) DE films. Using the same PDMS formulation but different procedures, we produced two model DE films with a thickness of approximately 50 μm. The two PDMS DE films suitably serve as a good-quality model film (EF1) and a low-quality model film (EF2) for this study, as shown by a large difference in the number of micron-sized defects found using micro-Raman techniques. The internal defects with various micron sizes in the two PDMS DE films can be quantitatively analyzed using an optical flaw inspection technique. According to two-parameter Weibull analysis, our assumption is that EF2 has a bimodal distribution of breakdown field (Eb) consisting of failure mode 1 in the early failure range and failure mode 2 in the late failure range. The values of the electric field (E) at the failure probability of 63.2%, defined as the scale parameter and regarded as DS, are 76.3 V μm−1 for EF1, and 39.1 and 69.6 V μm−1 for EF2, respectively. For the Eb distribution, the shape parameters estimated are 18.3 for EF1, and 4.7 and 10.2 for EF2, respectively. The results support the idea that there are different failure mechanisms between EF1 and EF2. The difference in the total number of internal defects, 12 for EF1 and 92 for EF2 per area of approximately 15 mm × 15 mm, should explain such a large variation in DS and Eb distribution. Our findings show the beneficial use of the quantitative analytical approach for micron-sized defects associated with the quality control and premature breakdown of DE films.

Several approaches have been used to minimize LWR in advanced resists. Various polymer and matrix properties, such as polymer molecular volume and free volume fraction, polymer dissolution, impact of activation energy of the deprotection reaction and distribution of small molecules in the polymer matrix have been shown to influence the functional behavior of the resist. We have developed polymerization methods to improve the incorporation and homogeneity of monomers, including PAG monomer, in an EUV resist polymer. Further, we report on use of a new cation which imparts reduced OOB character and a 30% improvement in LWR for a 28nm L/S feature with sensitivity of 10mJ/cm2 versus a control containing the TPS cation. Additionally this new material is capable of 21nm resolution. We also tested the new cation for outgassing by RGA and observed a 60% reduction in outgassing versus a TPS control.

Novel acetal-functionalized indacenodithiophene (IDT) moieties were developed in this study. Conductive polymers containing IDT units are promising candidates for synthesizing high-performance thermoelectric materials because their high charge-carrier mobility in the amorphous state has the potential to reduce the thermal conductivity without affecting its electric conductivity. Nevertheless, IDT-containing polymers such as poly(indacenodithiophene-co-3,4-ethylenedioxythiophene) (PIDT-EDOT) exhibit poor conductivity (0.43 S cm–1). Herein, we propose a novel strategy to control the dopant position near the benzylic position of the polymer backbone via a Lewis acid–base complex between a novel acetal-functionalized IDT (IDTa) unit and a dopant, nitrosyl hexafluorophosphate. The PIDTa-EDOT polymer exhibited an increase in doping efficiency and condensed π–π stacking, which increased its electrical conductivity. Moreover, PIDTa-EDOT exhibited a considerably lower thermal conductivity (0.09 W m–1 K–1) than that exhibited by PEDOT:PSS (0.16–0.39 W m–1 K–1). This was because of the reduced grain size of the polymer post doping. Consequently, PIDTa-EDOT exhibited an ∼30-fold increase in electrical conductivity (12.56 S cm–1) and an ∼6-fold increase in thermoelectric performance (ZT = 7.57 × 10–3) compared to those exhibited by PIDT-EDOT. Our research offers a new approach to increase electrical conductivity and decrease thermal conductivity simultaneously. This ultimately leads to the development of a high-performance thermoelectric material.

The American College of Surgeons requires trauma centers to track the number of injured patients admitted to a surgical service as well as nonsurgical admissions (NSAs) as a quality marker. We aim to compare the relationship between admitting service and outcomes in patients with isolated hip fracture (IHF). A 4-year retrospective cohort review of data collected from a single institution's trauma registry for adult patients with IHF was done. Patients were stratified into 2 groups based on admission to a surgical service versus NSA. Demographic and outcome variables including age, gender, Injury Severity Score (ISS), intensive care unit length of stay (ICU-LOS), deep venous thrombosis (DVT), and mortality rates were compared. Analysis of variance and χ test were used for data analysis with statistical significance defined as p < .05. A total of 629 patients with IHF were admitted. Of those, 30 (4.8%) were admitted to a surgical service and 599 (95.2%) were NSAs. Patients admitted to a surgical service were younger but average ISS was similar in both groups. Those admitted to a surgical service had a significantly shorter ICU-LOS than NSA patients (2.97 days vs. 4.91, p < .001). Readmission rate at 30 days (3.3% vs. 1.2%, p > .05) and DVT rates (0% vs. 0.4%, p > .05) were similar between groups. Mortality rates did not differ between groups (3.3% vs. 2.2%, p > .05). Patients with hip fracture requiring surgical intervention admitted to a trauma service have a shorter ICU-LOS than those admitted to nonsurgical services. Other quality markers were similar.

Choosing a benchmark for domestic large-cap equities is critical for plan sponsors because benchmarks play an important role in implementation of the portfolio management decision. As the sole purpose of active management is to generate excess returns over the benchmark, it is important that an equity benchmark representing this asset class be efficient, so that any outperformance of an active manager can be considered an outcome of the manager's skill. A more efficient benchmark for large-cap equity results in a historical average information ratio of zero for the universe of active managers. The key to generating alpha in this asset class then depends on one's ability to identify skillful managers.

Why do some individuals choose the professions they do? Is it for altruistic reasons? This article examines this question from the standpoints of sociobiology, evolutionary biology, game theory, and memetics. Implications for transcultural nursing are included. The Giger-Davidhizar Transcultural Assessment Model is presented as a nursing model and might explain altruism even beyond other models. An overview of the Giger-Davidhizar Transcultural Assessment Model is included.

The experiment of biaxial compressing was done with Fuping marble and the characteristic of acoustic emission in the process of damnification was studied, the linear relation between acoustic emission and damage variation under the condition of biaxial compressing was established and the occur mechanism of acoustic emission was also analyzed.

Los modelamientos asistidos por computador, se constituyen en una herramienta muy util pare la elaboracion de la evaluacion de la amenaza por flujos piroclasticos ante erupciones de volcanes activos. Un flujo piroclastico as el resultado del colapso gravitacional de una columna de erupcion o de domos volcanicos emplazados durante el evento eruptivo; este flujo puede ser modelado como un bloque que se desliza sobre una superficie. en donde la fuerza de gravedad es la que genera el movimiento y las propiedades intrinsecas del flujo, tales como la viscosidad y la cohesion, juegan un papel importante, en cuanto a la movilidad que puede alcanzar dicho flujo, la velocidad maxima lograda por el mismo y la distancia a la que puede llegar. De esta manera. Conociendo la dispersion alcanzada por flujos piroclasticos emitidos per el Volcan Cerro Machin (VCM) as posible establecer parametros que seran de utilidad para la simulacion de flujos piroclasticos por media del programa FLOW3D (SHERIDAN & KOVER 1997). Con estas simulaciones es posible establecer los escenarios de afectacion ante una eventual erupcion.

Abstract Learning strategies have been recognized as important predictors of mathematical achievement. In recent studies, it has been found that Asian students use combined learning strategies, primarily including metacognitive strategies, rather than rote memorization. To the best of the authors’ knowledge, there is only one prior study including South Korea in investigations of the relationship between learning strategies and mathematics achievement in PISA 2012. In that study, students were classified into groups using specific learning strategies, and their mathematics achievements were compared. There are two research gaps: (1) previous studies insufficiently explored how students use learning strategies in the South Korean education system, and (2) there is little research applying the nominal response model (NRM) to explore the association between learning strategy use and mathematics achievement in PISA 2012. Thus, the present study explores to what extent the NRM fits the data compared to the generalized partial credit model (GPCM). We created a learning strategy score from the NRM for South Korean students in PISA 2012 ( N = 3,310). Then, using correlation analysis and quadratic regression analysis, we identified linear and nonlinear relations between learning strategy scores from the NRM and mathematics achievement. The findings indicated that (1) NRM was a better fit for creating learning strategy scores than GPCM, (2) the average correlation coefficient between the learning strategy score and mathematics achievement was 0.18 ( p &lt; .05), and (3) for the curvilinear relationship between the learning strategy score and mathematics achievement, the standardized quadratic coefficient was − 0.090 ( p &lt; .001). Overall, the NRM represents an appropriate model for explaining the relationship between learning strategy and mathematical achievement. Additionally, high-performing South Korean students tend to primarily use metacognitive strategies with memorization. The negative quadratic coefficient captured the limited effect of the primary use of metacognitive strategies with memorization. The implications for the South Korean education system are discussed.