Potensi Sinamaldehid sebagai Anti Hiperpigmentasi secara In Silico

Permasalahan kulit yang sering ditemui yaitu hiperpigmentasi yang terjadi akibat adanya sintesis melanin berlebihan yang menyebabkan penggelapan warna kulit. Hiperpigmentasi dapat diatasi dengan agen anti hiperpigmentasi yang beraktivitas dalam menghambat proses sintesis melanin. Sintesis melanin dapat dihambat dengan berbagai cara salah satunya dengan menghambat aktivitas tyrosinase. Tyrosinase merupakan enzim yang berperan dalam mengkatalisis proses biosintesis melanin. Sinamaldehid merupakan senyawa bahan alam banyak ditemukan pada tanaman Cinnamomum burmanni mempunyai aktivitas sebagai antioksidan. Penelitian ini bertujuan untuk mengetahui potensi sinamaldehid dalam menghambat tyrosinase yang akan dibandingkan dengan native liganya secara in silico. Uji in silico dilakukan secara docking molecular dengan tahapan yaitu preparasi dan optimasi sinamaldehid, preparasi tyrosinase serta validasi dan docking. Metode docking molecular telah dinyatakan valid karena RMSD (root mean square distance) yang diperoleh tidak lebih dari 3 Å. Analisis data dilakukan dengan melihat energi ikatan yang dihasilkan dan ikatan yang terbentuk antara senyawa dengan residu asam amino pada protein. Nilai energi ikatan yang diperoleh antara ikatan sinamaldehid dengan tyrosinase adalah-6,21 kkal/mol. Sedangkan energi ikatan antara tyrosinase dengan native ligandnya -4,79 kkal/mol. Hal tersebut menunjukkan afinitas dari sinamaldehid pada protein tyrosinase lebih besar dibandingkan native ligandnya, sehingga sinamaldehid dikatakan memiliki potensi sebagai anti hiperpigmentasi dengan mekanisme molecular berupa inhibitor protein target tyrosinase sehingga dapat menghambat aktivitas enzim tyrosinase.

DYNAMICS OF INVOLUNTARY FORMATION OF EEG CORRELATION PATTERNS BY BIOFEEDBACK MECHANISM

The purpose of the work is to assess the dynamics of electroencephalogram (EEG) correlation development under involuntary control by biofeedback mechanism. Materials and Methods. The study involved 33 people (26 men and 7 women) aged 19–27 years. The paradigm of involuntary control was tested. The user did not have to arbitrarily change his/her state to achieve the desired color solution on the screen. The mode of color spectrum variation was determined by RGB channels, where each color was set according to correlation coefficients of EEG signals from a given pair of electrodes. The authors analyzed EEG correlation patterns in the biofeedback system through the color change on the screen. At the beginning, the user selected three most “pleasant” and three least “pleasant” colors. Feedback effect was multidirectional. Whenever the distance increased from the first to the fourth quantile for feedback experiments, the values were less than in the control. Whenever the distance decreased, the control values were less than the experimental ones. Results. A decrease in the RGB space mean square distance was revealed by the end of the experiment. Differences were also identified between the two study groups in the feedback experiments. The subjects were observed to maintain the dynamics during the experiment: if, in case of feedback, the distance to the preferred colors decreased, it decreased in the control experiment as well. The group approaching the target (preferred color) was initially at a larger distance from it, but had smaller values of roof-mean-square deviation (RMS). Keywords: brain-computer interfaces, involuntary control. Цель работы – оценка динамики формирования корреляции электроэнцефалограммы (ЭЭГ) в условиях непроизвольного управления по механизму биологической обратной связи. Материалы и методы. В исследовании приняли участие 33 чел. (26 мужчин и 7 женщин) в возрасте от 19 до 27 лет. Тестировалась парадигма непроизвольного управления, при которой пользователю не требовалось произвольно менять своё состояние для достижения нужного цветового решения на экране. Режим изменения цветовой гаммы определялся по каналам RGB, где каждый из цветов задавался исходя из корреляционных коэффициентов сигналов ЭЭГ с заданной пары электродов. Проведен анализ корреляционных паттернов ЭЭГ, реализованных в системе биологической обратной связи через изменение цветов на экране монитора. Предварительно пользователь выбирал три наиболее «приятных» и три наименее «приятных» цвета. Влияние обратной связи было разнонаправленным. Там, где от первого к четвёртому квантилю расстояние увеличивалось для экспериментов с обратной связью, значения были меньше, чем в контроле. Там, где расстояние уменьшалось, значения для контроля были меньше значений, полученных в эксперименте. Результаты. Выявлено уменьшение среднеквадратичного расстояния в пространстве RGB к концу эксперимента. Различия также были установлены между двумя исследуемыми группами в экспериментах с наличием обратной связи. Показано, что испытуемые сохраняют тренд динамики в ходе эксперимента: если при наличии обратной связи расстояние до предпочитаемых цветов уменьшалось, то оно уменьшалось и в контрольном эксперименте. Группа, демонстрировавшая приближение к цели (предпочитаемому цвету), имела изначально большее расстояние до неё, но меньшие значения среднеквадратичного отклонения. Ключевые слова: интерфейсы «мозг – компьютер», непроизвольное управление.

PROPERTIES OF DILUTE SOLUTIONS OF COPOLYMERS OF GLYCIDYLMETHACRYLATE AND METHYLPHEOPHORBIDE «a» IN DIMETHYLFORMAMIDE

The study of the rheological properties of polymers, and also the establishment of quantitative dependencies, along with the problem of the relationship of molecular characteristics with the synthesis conditions, is an important scientific and practical task. The solution of this problem gives to predict the behavior of polymers, to develop and find the optimal modes and parameters of obtaining materials with predetermined properties. For a research of chemical interaction between macromolecules in solutions, the dilute solutions rheology of copolymers of glycidylmethacrylate and methylphaeophorbide “a” in dimethylformamide was studied. The study of dilute solutions of the corresponding copolymers was carried out by viscometric method in the temperature range of 20-35 ºC. Copolymers of glycidylmethacrylate and methylphaeophorbide “a” of different composition were obtained by radical copolymerization in solution. The synthesized copolymers are characterized by molecular-weight characteristics determined by gel-permeation chromatography. It is established that the solutions of the copolymers correspond to the systems with the lower critical temperature of dissolution. The belonging of the studied solutions to the systems with the lower critical dissolution temperature is confirmed by the dependence of the Huggins constant on the temperature. From the obtained results it follows that the ball of the macromolecule shrinks with increasing temperature. The influence of solution temperature, molecular weight and composition of copolymers on their interaction with the solvent, expressed quantitatively through the parameters of the characteristic viscosity, the Huggins constant, the mean-square distance between the ends of macromolecular chains, is shown. The mean-square distance between the ends of the chains of polymer in the solution was estimated by the equation of Flory-Fox. It is shown that for the studied copolymers the specific index decreases with increasing temperature. It was determined that the introduction of the porphyrin fragment into the structure of the polymer macromolecule retains the character of the interaction of the macromolecular tangle with the solvent.

The Properties of Weak Solutions of N-Vinylpyrrolidone and Methyl Methacrylate Copolymers in Dimethylformamide

The rheology of solutions of N-vinylpyrrolidone and methyl methacrylate copolymers in dimethylformamide in the temperature range 20–35°C was studied. The influence of temperature and of the molecular weight and composition of the copolymers on their interaction with the solvent was shown, expressed quantitatively in terms of intrinsic viscosity, the Huggins constant, and the mean square distance between the ends of the macromolecular chains.

Automatic Approach for Lung Segmentation with Juxta-Pleural Nodules from Thoracic CT Based on Contour Tracing and Correction

This paper presents a fully automatic framework for lung segmentation, in which juxta-pleural nodule problem is brought into strong focus. The proposed scheme consists of three phases: skin boundary detection, rough segmentation of lung contour, and pulmonary parenchyma refinement. Firstly, chest skin boundary is extracted through image aligning, morphology operation, and connective region analysis. Secondly, diagonal-based border tracing is implemented for lung contour segmentation, with maximum cost path algorithm used for separating the left and right lungs. Finally, by arc-based border smoothing and concave-based border correction, the refined pulmonary parenchyma is obtained. The proposed scheme is evaluated on 45 volumes of chest scans, with volume difference (VD) 11.15±69.63 cm3, volume overlap error (VOE) 3.5057±1.3719%, average surface distance (ASD) 0.7917±0.2741 mm, root mean square distance (RMSD) 1.6957±0.6568 mm, maximum symmetric absolute surface distance (MSD) 21.3430±8.1743 mm, and average time-cost 2 seconds per image. The preliminary results on accuracy and complexity prove that our scheme is a promising tool for lung segmentation with juxta-pleural nodules.

The Effect of Footrest on Standing Postural Control

The use of a footrest while performing activity in standing is frequently associated with improvement of a user’s well-being however no information exists on the role of a footrest in improving postural stability. The aim of the study was to evaluate the effects of using a footrest in postural control. Twenty healthy young volunteers were tested using three experimental conditions: standing with two feet on the force platform and standing on the force platform when one foot was placed on a 15 cm footrest positioned in front or laterally. The mean and root mean square distance, range and velocity of the center of pressure (COP) were calculated in the anterior-posterior (AP) and medio-lateral (ML) directions using the force platform data. The COP displacements in AP and ML directions increased in conditions of standing with one foot placed on the footrest regardless of its location. Standing with eyes closed increased COP displacements further. The outcome of the study suggests the importance of using COP measures for evaluation of postural stability and provides additional information needed for optimization of working conditions involving standing with a footrest.

Application Potential of Four Nontraditional Similarity Metrics in Hydrometeorology

This paper presents a review and assessment of four nontraditional similarity metrics that can be applied to hydrological and meteorological data. These metrics are 1) the uncentered correlation coefficient, 2) the Hodgkin–Richards index, 3) the Petke index, and 4) the Wang–Bovik index. The first metric has been widely used in hydrometeorology, and the other three have been proposed in other disciplines for similarity analysis. It is demonstrated that these similarity metrics, in their original formulations, either do not actually have the purported advantage over the traditional Pearson correlation coefficient or are not suitable for some hydrometeorological applications. They are reformulated in this study to address these deficiencies. The resulting modified metrics are unitless, bounded, and proportional to the Pearson correlation coefficient, and three of them have the confirmed advantage of explicitly penalizing for differences in the mean and/or in the variance. Two application examples are used to demonstrate the applicability of these similarity metrics in hydrometeorology. A metavalidation model and a graphical tool (Taylor diagram) are used to evaluate the performances of these similarity metrics. In a case study of analog analysis, the Wang–Bovik index stands out as the best metric for simulation of the human perception of similarity between two-dimensional patterns, whereas the modified Petke index and the traditional root-mean-square distance may perform slightly better than the others in the regions with a very large difference between the variances.

Dispersion of aerosol particles in the free atmosphere using ensemble forecasts

The dispersion of aerosol particle pollutants is studied using 50 members of an ensemble forecast in the example of a hypothetical free atmospheric emission above Fukushima over a period of 2.5 days. Considerable differences are found among the dispersion predictions of the different ensemble members, as well as between the ensemble mean and the deterministic result at the end of the observation period. The variance is found to decrease with the particle size. The geographical area where a threshold concentration is exceeded in at least one ensemble member expands to a 5–10 times larger region than the area from the deterministic forecast, both for air column "concentration" and in the "deposition" field. We demonstrate that the root-mean-square distance of any particle from its own clones in the ensemble members can reach values on the order of one thousand kilometers. Even the centers of mass of the particle cloud of the ensemble members deviate considerably from that obtained by the deterministic forecast. All these indicate that an investigation of the dispersion of aerosol particles in the spirit of ensemble forecast contains useful hints for the improvement of risk assessment.

Effect of Cardiovascular Fatigue on Postural Stability

Context:Previous research has demonstrated that localized leg muscle fatigue induced by lower extremity exercises (e.g., squat jumps, sprints, and treadmill running) has an adverse effect on postural stability.Objective:To assess the effect of cardiovascular fatigue induced by upper extremity exercise on postural stability.Design:Repeated measures.Participants:Fourteen healthy young adults between the ages of 22 and 30 years (7 male and 7 female).Intervention:Participants performed an exercise protocol on an upper-body ergometer to induce cardiovascular fatigue.Main Outcome Measures:Postural sway, represented by center of pressure excursion, during bilateral standing in two different foot positions.Results:In a tandem standing position, mediolateral mean distance, root mean square distance, resultant power, and centroidal frequency increased signifcantly after inducement of cardiovascular fatigue.Conclusion:Cardiovascular fatigue adversely affects postural stability.