Correct Mode Research Articles

The Evaluation of Variations in Patterns of Sphenoid Sinus Pneumatization Using Computed Tomography in a South Indian Population.

Background and objectiveKnowledge about sphenoid sinus pneumatization is critical for skull base surgeries and functional endoscopic sinus surgery (FESS) in order to avoid serious complications like postoperative meningitis, sinusitis, cerebrospinal fluid (CSF) rhinorrhea, and intracranial hematoma. In this study, we aimed to assess the proportion of anatomical variants in sphenoid sinus pneumatization and to determine the common sphenoid pneumatization pattern in a South Indian population.MethodsThis retrospective study was conducted over a period of six months from July 2019 to December 2019 among 573 patients who underwent non-contrast CT (NCCT) or contrast-enhanced CT (CECT) of the brain, paranasal sinuses (PNS), orbit, and face.ResultsMost of the patients were in the age group of 20-39 years. The male-to-female ratio was 2.45:1. Among the posterior extensions, the most common variant was type D, followed by type C, type B, and type A. Among the clival extensions, the most common variant was Cliv-A, followed by Cliv-B, Cliv-C, and Cliv-D. The most common lateral wall pneumatization was bilateral lateral wall pneumatization followed by unilateral sinus wall pneumatization. Lat-A was the most common lateral wall pneumatization pattern followed by Lat-D, Lat-B, and Lat-C.ConclusionOur study intends to classify the sphenoid sinus pneumatization pattern and identify the most common variant among them, thereby guiding the skull base and FESS surgeons in choosing the correct mode of the operative procedure and also anticipating and avoiding complications of surgery.

New Series of VEGFR-2 Inhibitors and Apoptosis Enhancers: Design, Synthesis and Biological Evaluation.

BackgroundCancer is still a major world health threat, causing a high rate of mortality. VEGFR-2 inhibitor anticancer agents are of great significance. However, they showed some serious side effects.PurposeTo discover new effective and safer anticancer agents, a new series of piperazinylquinoxaline-based derivatives was designed and synthesized on the basis of the pharmacophoric features of VEGFR-2 inhibitor drugs.MethodsThe new candidates were evaluated against A549 lung cancer cells, HepG-2 hepatoma cells, Caco-2 colon cancer cells, MDA breast cancer cells, and VEGFR-2 kinase. Moreover, cell cycle kinetics and apoptosis rates were studied in HepG-2 cells treated with compound 11, which was the most promising candidate.ResultsThe new derivatives revealed better antitumor results (IC50 from 6.48 to 38.58 µM) against the aforementioned cancer cell lines than sorafenib. Also, the new candidates showed VEGFR-2 inhibition with IC50 values ranging from 0.19 to 0.60 µM compared to 0.08 µM for sorafenib. Compound 11, meanwhile, showed IC50 values equal to 10.61, 9.52, 12.45, 11.52, and 0.19 µM against the cancer cell lines and VEGFR-2, respectively. Moreover, compound 11 raised the apoptosis rate in HepG-2 cells from 5% to 44% and caused 4, 2.3, and 3-fold increases in BAX/Bcl-2 ratio, caspase-3 level, and P53 expression, respectively, compared to control untreated cells. Finally, the new derivatives displayed the correct binding mode into VEGFR-2 kinase pocket, giving interactions with the essential residues.ConclusionThis work suggests that compound 11 is a very significant anticancer candidate, and piperazinylquinoxaline is an important scaffold in the development of new potential effective and safer VEGFR-2 inhibitor agents.

Effect of foreign direct investment on gross national income in Nigeria, 2006-2017

Effect of foreign direct investment on gross national income in Nigeria, 2006-2017 Kelechi Johnmary Ani Alex Ekwueme Federal University, Nigeria E-mail: kelechi.ani@funai.edu.ng Chigozie Onu Nnamdi Azikiwe University, Nigeria E-mail: asiano.jc@gmail.com Submission: 11/4/2020 Revision: 12/15/2020 Accept: 1/5/2021 ABSTRACT The study analyzed the effect of foreign direct investment on gross national income over the period of 2006- 2019. The main type of data used in this study is secondary; which were sourced from various publications of Central Bank of Nigeria, such as; Statistical Bulletin, Annual Reports and Statement of Accounts. The regression analysis of the ordinary least square (OLS) is the estimation technique that was employed in this study to determine the effect of the Direct Foreign Investment on gross national income in Nigeria. The cointegration test showed existence of a long run relationship and an indication that 1 cointegrating vectors exist at 5% level of significance among the variables which was corrected with error correction mode (ECM). The result showed that foreign direct investment had a positive effect on gross national income during the period 2006 – 2019. It also revealed that gross domestic product, exchange rate and unemployment rate has a positive effect on gross national income in Nigeria during the same period. The study recommends that government should try to develop trade zones, which are solely based on free economic movements and policies. The study recommends official re-consideration of different determinants of gross national income (GNI) attractions. Government incentives, infrastructure and policies should be put in place to make it easy for general foreign investors, to find Nigeria safe and reliable to invest. Finally, unique fiscal and monetary policies should be formed to strengthen the other macroeconomic variables which will help to overcome the situation of shocks in Nigeria while hosting Foreign Direct Investment inflow for future sustainable economic development.

Reduced order modeling of soft-body impact on glass panels

In the paper, strategies for reduced order modeling of glass panels subjected to soft-body impact are developed by means of dynamic substructuring. The aim is to obtain accurate and computationally efficient models for prediction of the pre-failure elastic response. More specifically, a reduction basis for the subsystem representing the glass panel is established using correction modes, being fixed-interface component modes that considers loading on the substructure boundary. The soft-body impactor is effectively modeled by a nonlinear single-degree-of-freedom system, calibrated by experimental data. Furthermore, a simplified and computationally efficient modeling approach is proposed for the contact interaction between the glass panel and the impact body. An experimental campaign was carried out to validate the developed models. In particular, the glass strain was measured on simply supported monolithic glass panels subjected to soft-body impact. Additional impact tests were performed to determine the dynamic characteristics of the impactor. Moreover, a detailed numerical reference model was developed to evaluate the discrepancy between the experimental tests and the results provided by the reduced order models. The developed models show good agreement with the experimental results. For the studied load cases, it is shown that an accurate prediction of the pre-failure glass strain can be obtained by systems including only a few generalized degrees-of-freedom.

Structural Optimization of Vented Brake Rotors with a Fully Parameterized Model

Vented brake rotors used in an automobile behave similarly to centrifugal fans, drawing cool air from the inboard side, passing it through the disc vents, and exhausting it from the periphery. A vented brake rotor with a better heat dispersing ability is often superior to a solid rotor, in both thermal performance and brake efficiency. In this research, a fully parameterized model for a ventilated brake rotor is created using the ANSYS Parametric Design Language, to uniquely define the rotor’s geometry. With this parameterized model, two structural optimization cases are studied in this paper. The first one investigated is a modal frequency separation problem: The frequency differences in a tangential mode sandwiched between two nodal diameter modes of the brake rotor model are maximized. An automatic identification scheme for extracting correct mode orders is implemented in the program to track the correct modes during optimization. The second case is a thermal deformation problem: The distortion on the frictional surfaces of the rotor loaded with heat flux generated during the braking process is minimized. The optimization results show that a brake rotor design with a thinner outboard disc and a thicker inboard disc provides a great choice for rotor coning reduction.

Docking Ligands into Flexible and Solvated Macromolecules. 8. Forming New Bonds─Challenges and Opportunities.

Over the years, structure-based design programs and specifically docking small molecules to proteins have become prominent in drug discovery. However, many of these computational tools have been developed to primarily dock enzyme inhibitors (and ligands to other protein classes) relying heavily on hydrogen bonds and electrostatic and hydrophobic interactions. In reality, many drug targets either feature metal ions, can be targeted covalently, or are simply not even proteins (e.g., nucleic acids). Herein, we describe several new features that we have implemented into Fitted to broaden its applicability to a wide range of covalent enzyme inhibitors and to metalloenzymes, where metal coordination is essential for drug binding. This updated version of our docking program was tested for its ability to predict the correct binding mode of drug-sized molecules in a large variety of proteins. We also report new datasets that were essential to demonstrate areas of success and those where additional efforts are required. This resource could be used by other program developers to assess their own software.

A Bidirectional Grid-Connected DC–AC Converter for Autonomous and Intelligent Electricity Storage in the Residential Sector

Controlling the cost of electricity consumption remains a major concern, particularly in the residential sector. Smart home electricity management systems (HEMS) are becoming increasingly popular for providing uninterrupted power and improved power quality, as well as for reducing the cost of electricity consumption. When power transfer is required between a storage system and the AC grid, and vice versa, these HEMS require the use of a bidirectional DC–AC converter. This paper emphasizes the potential value of an almost unexplored topology, the design of which was based on the generation of sinusoidal signals from sinusoidal half waves. A DC–DC stage, which behaved as a configurable voltage source, was in series with a DC–AC stage, i.e., an H-bridge, to achieve an architecture that could operate in both grid and off-grid configurations. Wide bandgap power switches (silicon carbide metal-oxide-semiconductor field-effect transistors [MOSFETs]), combined with appropriate control strategies, were the keys to increasing compactness of the converter while ensuring good performance, especially in terms of efficiency. The converter was configured to automatically change the operating mode, i.e., inverter or rectifier in power factor correction mode, according to an instruction issued by the HEMS; the latter being integrated in the control circuit with automatic duty cycle management. Therefore, the HEMS set the amount of energy to be injected into the grid or to be stored. The experimental results validate the operating modes of the proposed converter and demonstrate the relevance of such a topology when combined with an HEMS, especially in the case of an AC grid connection. The efficiency measurements of the bidirectional DC–AC converter, performed in grid-connected inverter mode, show that we exceeded the efficiency target of 95% over the entire output power range studied, i.e., from 100 W to 1.5 kW.

Induced fit docking workflow based on charmm-gui modules: LBS Finder & Refiner and High-Throughput Simulator

Molecular docking is a preferred method to predict ligand binding modes and their binding energy to target protein receptors, which is a critical first step in the early phase structure-based drug discovery. However, there is a persistent problem in docking that can be attributed to the induced fit effect, where the receptor binding site undergoes induced fit conformational changes upon ligand binding to achieve the correct binding mode. To solve this problem, we present a reliable stepwise docking workflow based on CHARMM-GUI LBS Finder & Refiner and High-Throughput Simulator.

Assessment and Integral Indexing of the Main Indicators of Oil and Gas Companies by Circular Convolution

In the oil and gas industry, which is the basis of the Russian energy market, a significant and urgent question arises: How to distribute companies according to their investment attractiveness? Accordingly, quantitative indicators are needed. Lacking extensive experience in the practical implementation of fundamental rating tools, work is needed to develop methodologies of weighting coefficients and lists, built on the experience of the “big three” rating agencies. The article proposes an algorithm for forming an integral rating of companies based on financial reporting indicators and the author’s rules of fuzzy logic based on the principle of “circular convolution”, from the best to the slave, deepening the analysis to the center, when all companies are exhausted and places in the rating are distributed. The problem of assessing and integrally indexing the indicators of large companies in leading sectors of the economy (e.g., oil and gas, banks, electricity) is becoming manifest, while it is obvious that there is competition between large companies of the country’s leading industries for state investment resources. The nature of the leading industries is such that it is necessary to assess the quality of the company’s functioning based on the formation of rating groups. Based on the rating, investments are distributed among the companies under consideration. The author has developed a portfolio model that is analogous to the Harry Max Markowitz model, which does not contradict this model but allows consideration of a broader range of risk assessments used in the model (for example, the rating of companies). The optimal portfolio is built, taking into account the resulting index and the initial grouping in the hierarchical data correction mode. The logically sequential method of circular convolution of four important indicators to an integral index and a mathematically substantiated method for optimizing the minimax portfolio presented in the work will allow the investor to develop optimal (from the point of view of the transparency of the apparatus used, mathematical feasibility and time spent on the implementation of the software package) tools for investing and enlarging his capital.

DIAGNOSTICS OF THE OPTIMAL OPERATING MODES OF GAS TURBINE COMPRESSOR STATIONS BASED ON THE ANALYSIS OF TECHNOLOGICAL PROCESSES

The article is dedicated to the analysis of the influence of the seasonally changing ambient temperature on the technological parameters of the compression process at a gas turbine compressor station for the transportation of natural and associated gas collected from oil and gas fields by an offshore subsea gas pipeline. As a result of the analysis, indicators of suction and discharge pressure, compressor capacity, ambient temperature during the summer and winter months were collected at each stage of a multi-unit two-stage compressor station. The indicators were divided into intervals, the number of measurements in the interval was determined, and graphs of the dependence of the number of measurements on the average value of the interval were built. As a result of the analysis of the graphs, the complex influence of technological parameters and ambient temperature on the performance of gas turbine compressors was evaluated. To compare the results and study the effect of the parameters on the operating mode and efficiency of the compressor station, the numerical value of the criterion as the ratio of the maximum number of measurements to the average value of the corresponding interval for each parameter was calculated. For both 1st- and 2nd-stage compressors, the value of this criterion for productivity was found to be almost twice as low in winter compared to summer. For this reason, there is a need to develop measures that can ensure the operation of the compressor station in the optimal operating mode. As a result of the analysis, it was found that in the 1st stage gas turbine compressors, due to increase of the inlet pressure, which is a positive factor for the compressor, by 16.4% (from 58 psi to 67.5 psi) in summer compared to winter, and due to the increase of the outlet pressure, which is the negative factor, by 0.9% (from 285 psi to 288 psi) and an increase in ambient temperature of 36o F (from 42o F to 80.5o F), the productivity is decreased by 15.2% (from 40.15 MMSCFD to 34.05 MMSCFD) to). In 2nd-stage gas turbine compressors, due to no change of the inlet pressure, which is a positive factor for the compressor, in summer, compared to winter (273 psi in both cases), and due to the decrease of the outlet pressure, which is a negative factor, by 0.2% (from 807.5 psi to 805.5 psi. ) and an increase in ambient temperature of 36o F (from 42o F to 80.5o F), productivity decreased by 10.1% (from 49.05 MMSCFD to 44.05 MMSCFD). Thus, 10.1% of the 15.2% decrease in the productivity of gas turbine compressors in the summer season is due to the increase in ambient temperature, while the remaining 5.1% is due to the organization of technological processes. Taking into account this factor in the field, the selection of the correct technological mode in the gas transportation system allows to prevent the loss of large amounts of gas. Taking into account the design features of gas turbine compressor units, it is concluded that the 10.1% decrease in productivity in the 2nd stage gas turbine compressors in the background of the constant no-change of compressor inlet and outlet pressures in summer and winter is due to automatic decrease in RPM of gas turbines from nominal 15000 cycles/min and thus the decrease of the power of gas turbines due to the overload in summer. Considering the fact that each turbine consumes 30,000 m3 of fuel gas per day, the 360,000 m3 gas per day for fuel at the station is taken from the outlet of the 2nd stage gas turbine compressors, and these turbines are overloaded, the fuel gas is considered to be taken from another source. By feeding all the turbines of the station from the outlet of the 1st stage compressors, it is possible to reduce the load on the interstage collector of the station, increase the productivity of the 1st stage compressors and direct the gas compressed by the 2nd stage compressors to the whole outlet pipeline. As a result of this technological operation, an additional 200,000-250,000 m3 of gas per day can be transported through the compressor station. This technique is recommended for multivariate analysis of various technological processes. As a result of the study, a technological scheme was proposed for increasing the productivity of a gas turbine compressor station by 3-4% by changing the source of fuel gas extraction. Keywords: gas turbine, compressor, natural gas pressure, ambient temperature, productivity, fuel gas, statistical method.

SIGNIFICANCES OF DAILY DISPOSABLE CONTACT LENSES DURING COVID-19

Contact lens is one of the preferred modes of refractive correction for children and adults. With proper care and maintenance, even during pandemic of COVID-19, contact lenses can be prescribed and worn by the patients without much fear of Coronavirus infection. Till now there is no strong clinical evidence that proves contact lenses are not safe to wear during COVID-19. But considering patient’s health and hygiene, various literatures have suggested that with compared to conventional or yearly disposable contact lenses, daily disposable contact lenses are safer to use during COVID-19. Since the daily disposable lenses are discarded daily after use at the end of the day, there is no need of extra care regarding manual cleaning and maintenance. Daily disposable lenses may have a very less or even no deposits and debris so makes patient more comfortable all over the time with less risk of Coronavirus infection.

A fast, fully distributed nonlinear model predictive control algorithm with parametric sensitivity through Jacobi iteration

Centralized model predictive control is impractical for many complex systems due to communication burden and robustness issues. For these systems, distributed model predictive control (DMPC) is an alternative control strategy. In DMPC, the use of nonlinear first-principle model improves the prediction accuracy. However, it also brings about computational delay due to time-consuming optimization of large, non-convex nonlinear programs, which can then degrade the control performance. In this work, a fully distributed nonlinear model predictive control (DNMPC) algorithm is developed to accelerate control feedback. The input computation procedure contains background and online stages, in which prediction–correction mode is applied. In the background stage, the future state is predicted one step forward based on the nominal plant model. Each controller optimizes its own local input and exchanges latest information with other controllers to improve decision making. After distributed optimization, the local controllers collect optimality information to prepare for future computation. When the true state is available, the state prediction error can be calculated. Each controller formulates its local sensitivity equation based on parametric sensitivity. All the sensitivity equations are solved in parallel with application of the Jacobi iterative method. After solution, the nominal optimum is updated with the correction vector and then implemented to the plant. The theoretical analysis of the proposed method is presented. Four case studies are given to demonstrate the effectiveness of the proposed algorithm.

Critical Factors of Dose Distribution in Breast Cancer Tomotherapy With Metallic Port Breast Tissue Expander: Image Correction, Delivery Mode, and Volume Impact.

Objectives: Breast reconstruction helps patients enhance their body image after mastectomy. Metallic ports in tissue expanders lead to dose attenuation during radiotherapy. Tissue expander volume shifts the metallic port position, possibly causing various dose alterations. This study aimed to evaluate the impact of the MAGNA-SITETM tissue expander volume on tomotherapy. Methods: Boluses and MAGNA-SITETM were placed on a Rando phantom to simulate the tissue expander under the pectoralis major. Computed tomography simulation images were transformed through replacing the electron density of (a) metallic artifact region only (Image metallic port) and (b) metallic port and artifact regions (Image Homo). Planning was calculated using fixed-beam and helical-mode techniques. Radiation was delivered with different volumes of the tissue expander. Results: Integrated 997 dose points were calculated. Planning with Image metallic port provided a calculated dose significantly closer to a realistic dose. The percentage of doses achieving the prescribed dose was significantly higher in the helical mode. In layer 2, the 100-mL tissue expander had a significantly lower measurement dose than all other volumes. Volume 150 mL had the highest increase in the measured dose difference from the plan dose at layer 2. Volume 250 mL had the highest percentage of measurement doses passing the 5% dose difference from plan dose. The coldest dose areas were noted in layers 1 and 2, especially in the metallic port–direct image mode. The average dose reduction of the measured cold areas was 6.03 ± 1.94%. Conclusion: Dose distribution was affected by the volume of the metallic port tissue expander. Tomotherapy with proper image heterogeneity correction and helical mode can reduce the attenuation from the metallic port. A tissue expander volume of 150 to 250 mL is suitable. Patients with high risk at the chest wall should be evaluated carefully to avoid underdosing. Radiation oncologists should closely cooperate with plastic surgeons to optimize treatment for each patient.

Nonlinear control of grid-connected PV systems using active power filter with three-phase three-level NPC inverter

Grid-connected photovoltaic (PV) systems have become a significant area of interest for research scientists. Given this, this article presents a nonlinear control of grid-connected PV systems using active power filter (APF) with three-phase three-level neutral point clamped (NPC) inverter. The control objectives involve: (1) Forcing the PV output voltage to track a reference signal provided by the MPPT block in order to produce their maximum power, (2) Regulating the DC link voltage to satisfy a correct operation mode of the three-phase active power filter, and (3) Satisfying power factor correction (PFC) objective at the point of common coupling, PCC. Therefore, the suggested control strategy includes a cascade structure of two loops. The inner-loop regulator is designed using the sliding mode control technique and Lyapunov approaches to ensure the PFC objective by forcing the grid current to follow a given reference signal. The Outer-loop consists mainly of a proportional-integral (PI) regulator so that to regulate the output voltage. Further, the theory of instantaneous real power is used to calculate reference harmonics. The effectiveness of the proposed controller is demonstrated through simulation results using MATLAB/Simulink.

Сутність та аналіз оздоровчих систем

In the article, based on the analysis of data from special literature, generalization of the experience of leading experts and personal experience, a number of conclusions are made. Regarding the essence and analysis of health systems, an extremely important solution to the problem of introducing valeological education and training specialists with a high level of knowledge of individual health and ways to achieve them has been proved. It has been established that this approach makes it possible to formulate a new attitude towards health in society, the cultivation of a healthy lifestyle. Proved additional responsibility for physical education and health education for the training of specialists to work in this direction. It was revealed that health systems are systems of theoretical knowledge and practical methods that ensure the preservation of health, the formation of a healthy lifestyle. It has been proven that health systems contribute to the preservation and strengthening of the health of applicants for education gradually and naturally without applying complex methods and artificial preparations to the body. Respiratory exercises are recognized as relevant among the health systems. Scientific research confirms that breathing exercises are an important and effective therapeutic tool. Systematic special breathing training can significantly increase the efficiency and economy of external breathing and at the same time increase, make more stable the physiological reserves and adaptive capabilities of the body. In the process of scientific research, it was found that there is a significant variety of health systems. The analyzed health systems combine certain common components. These include: the correct mode of work and rest; daily physical activity; a full night's sleep; optimism and the ability to control emotions; the ability to withstand stress, relax and have a good rest, etc. It is recommended to use health systems for the prevention of diseases, as well as for effective healing of the body as a whole.

Joint Inversion of Rayleigh and Love Dispersion Curves Extracted from Ambient Seismic Noise Based on Secular Function

Traditional multi-mode dispersion curve inversion requires correct mode discrimination. However, when the stratum contains complex structures such as low-speed soft interlayer or high-speed hard interlayer, the dispersion curve may show phenomena such as “mode kissing” and “mode jumping”, which can easily cause mode misjudgment and lead to erroneous inversion results. Based on the “secular function”, this paper constructs a new type of objective function applied to the inversion of dispersion curve. This objective function does not require prior mode discrimination, which effectively solves the “mode misjudgment” problem of multi-mode dispersion curve inversion. The joint inversion of Rayleigh and Love dispersion curves extracted from ambient seismic noise is used to improve the constraint of the inversion and avoid the inversion falling into a local minimum in the case of a large-scale search of parameters. Finally, a numerical simulation was performed to verify the feasibility of the new inversion method.

The Myopia Control in Real Clinical Practice: The Results of an Expert Study

The article presents expert study results about myopia control. The study was conducted by Russian eye care practitioners in 2019.Purpose. to summarize the views of eye care practitioners on the problem of myopia control in Russia.Methods. The study was conducted by mailing (sending) questionnaires to practitioners. The questionnaire contained 9 questions. Base questionnaire was developed by British Contact Lens Association (BCLA) for global study, translated into Russian and updated with items of interest to Russian practitioners.Results. 356 questionnaires were received and processed. Concern increasing frequency of pediatric myopia was highest (9.0 ± 0.08 on a 10 point scale). Orthokeratology was perceived to be the most effective method of myopia control, followed by myopia control soft contact lenses and increased time outdoors. Perceived effectiveness rated as percentage was 50.7 ± 1.6 %, 44.9 ± 1.8 % и 42.9 ± 1.7 % respectively. Perifocal spectacles correction was perceived to be the most effective method in the Southern area of Russia (56.8 ± 11.1 %), atropine — in the Northwestern Federal District (39.5 ± 7.1 %), scleroplasty — in the Far East (55.1 ± 7.6 %). Under-correction was perceived to be the least effective method in all areas (11.6 ± 1.0 %). Increased time outdoors was a priority for most practitioners (on average 94.0 ± 7.8 prescriptions per month by one practitioner). Practitioners prescribed single vision spectacles as the primary mode of correction for myopic patients (47.2 ± 3.6 prescriptions per month by one practitioner). Phenylephrine instillation was used often (49.4 ± 3.6 prescriptions per month by one practitioner). This trend was in most areas. Vision therapy was used most frequent in Siberia and the Urals and in the Far East (70.4 ± 11.5 и 20.0 ± 5.2 prescriptions per month by one practitioner respectively). The most common reasons practitioners gave for not adopting myopia control strategies were: they were felt to be uneconomical (42.1 %); they considered there to be inadequate information about the modalities (22.2 %). 45 % practitioners from the Far East called the last reason the main one. 42.9 % practitioners from Northwestern Federal District did not believe that these are any more effective methods then single vision correction.Conclusion. The active promotion and introduction into everyday clinical practice of myopia control methods that have proven to be highly effective could help reduce the frequency of progressive and degenerative myopia

Spatio-Temporal Modeling of Immune Response to SARS-CoV-2 Infection

COVID-19 is a disease occurring as a result of infection by a novel coronavirus called SARS-CoV-2. Since the WHO announced COVID-19 as a global pandemic, mathematical works have taken place to simulate infection scenarios at different scales even though the majority of these models only consider the temporal dynamics of SARS-COV-2. In this paper, we present a new spatio-temporal within-host mathematical model of COVID-19, accounting for the coupled dynamics of healthy cells, infected cells, SARS-CoV-2 molecules, chemokine concentration, effector T cells, regulatory T cells, B-lymphocytes cells and antibodies. We develop a computational framework involving discretisation schemes for diffusion and chemotaxis terms using central differences and midpoint approximations within two dimensional space combined with a predict–evaluate–correct mode for time marching. Then, we numerically investigate the model performance using a list of values simulating the baseline scenario for viral infection at a cellular scale. Moreover, we explore the model sensitivity via applying certain conditions to observe the model validity in a comparison with clinical outcomes collected from recent studies. In this computational investigation, we have a numerical range of 104 to 108 for the viral load peak, which is equivalent to what has been obtained from throat swab samples for many patients.

Safe Contact Lens Practices during Coronavirus (COVID-19) Pandemic

World is threatened by different variants of Coronavirus to an extent that life has been jeopardized in all services including eye care facility. Contact lenses which are one of the preferred modes of vision correction are not an exception to COVID-19 infection. Recently there is confusion among practitioners and patients regarding the safety of contact lens use during COVID-19. This review article summarizes the current recommendations and findings regarding contact lens use during COVID-19. Though eye health professionals and contact lens users are at risk to contract Coronavirus, with proper care, maintenance and disinfection techniques, it would be safe to continue wearing contact lenses. There is currently no strong evidence to suggest that contact lenses are not safe to wear during COVID 19 times. Eye care practitioners responsible for contact lens application must wear special surgical masks, protective glasses or visors and disposable waterproof gloves. Regarding soft contact lenses, preferably daily disposable lenses should be used from the sterile packages. Similarly for rigid gas permeable lenses, lenses made up of fluoropolymer contained in sealed packages must be motivated for the individuals. Since the infected hands can bring the virus to the eyes, contact lens users should avoid touching the nose, mouth and eye unnecessarily. Contact lens after each use must be disinfected with hydrogen peroxide solutions with a special catalyst container. In the case of eye redness and Flu like symptoms, contact lens trial and wearing practices should be suspended or postpone till the condition becomes normal. To minimize the contact time between the patient and examiner soft copy of the instruction sheet, teleconsultation should be motivated. Though the eye is an unlikely site for Coronavirus infection, eye doctors should warn the contact lens wearers to follow scrupulous contact lens hygiene rules.

Molecular Perturbation Effects in AFM-Based Tip-Enhanced Raman Spectroscopy: Contact versus Tapping Mode.

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for nondestructive and label-free surface chemical characterization at nanometer length scales. However, despite being considered nondestructive, the interaction of the TERS probe used in the analysis can alter the molecular organization of the sample. In this study, we investigate the role of the atomic force microscopy (AFM) feedback (contact mode and tapping mode) on molecular perturbation in TERS analysis of soft samples using a self-assembled monolayer (SAM) of 2-chloro-4-nitrobenzene-1-thiol (Cl-NBT) as a test sample. Surprisingly, the tapping mode shows a consistently higher TERS signal resulting from a minimal perturbation of the Cl-NBT SAM compared to the contact mode. This study provides novel insights into the choice of the correct AFM-TERS operation mode for nanoscale chemical analysis of soft and delicate samples and is expected to expedite the growing application of TERS in this area.