Revised Periodic Boundary Conditions: Fundamentals, Electrostatics, and the Tight-Binding Approximation

Many nanostructures today are low-dimensional and flimsy, and therefore get easily distorted. Distortion-induced symmetry-breaking makes conventional, translation-periodic simulations invalid, which has triggered developments for new methods. Revised periodic boundary conditions (RPBC) is a simple method that enables simulations of complex material distortions, either classically or quantum-mechanically. The mathematical details of this easy-to-implement approach, however, have not been discussed before. Therefore, in this paper we summarize the underlying theory, present the practical details of RPBC, especially related to a non-orthogonal tight-binding formulation, discuss selected features, electrostatics in particular, and suggest some examples of usage. We hope this article to give more insight to RPBC, to help and inspire new software implementations capable of exploring the physics and chemistry of distorted nanomaterials.Comment: 17 pages, 5 figures, 2 table

Gender differences in components of insulin-like signaling pathway in kidney tissues in local and advanced clear cell renal cell carcinoma

Objective: study of components of an insulin-like signaling pathway in kidney tissues in local and advanced clear cell renal cell carcinoma depending on the gender of patients. Materials and methods: the object of the study was conditionally intact kidney tissue and tumor and perifocal tissues obtained during the surgical treatment of 100 patients with histologically confirmed clear cell kidney cancer (local cancer (Т1-2N0М0) n=50, advanced cancer (Т3-4N0М1) n=50). Levels of the IGF-1, IGF-2, IGFBP-1 and IGFBP-2 growth factors (Mediagnost, Germany) and STH-releasing (Peninsula Laboratories International, USA) were determined by ELISA using standard test systems. The results were analyzed using Statistica 6.0 (Stat-Soft, 2001). Results: levels of IGFВР-2 and STH-releasing in conditionally intact tissues in women were 44% and 40% lower than in men, respectively. The IGFВР-2 level in perifocal tissues of women was 38% higher than in men, while STH-releasing was lower by 1.9 times. Tumor tissues of local kidney cancer in women showed significant decrease in IGF-1 by 25%, IGFВР-1 by 29% and IGFВР-2 by 2 times. Levels of IGFBP-1 and IGFBP-2 in conditionally intact tissues of women with advanced cancer were 2 and 2.7 times lower, respectively, compared to men. IGFBP-2 and STH-releasing in perifocal tissues of women were increased by 43.8% and 44.6%, respectively. In tumor tissues of women with advanced kidney cancer, levels of IGF-1 were 1.7 times higher, IGF-2 – 31% lower, IGFBP-2 – 2.8 times lower and STH-releasing – 36% lower, compared to men. Conclusions: IGFBP-2 in all studied kidney tissues in local and advanced cancer was an identically variable index characterizing gender differences in the body’s reaction to the tumor process

Cancer treatment and research in the context of COVID-19 pandemic: the experience of foreign countries

The coronavirus disease 2019 (COVID-19) has rapidly swept the world Patients with cancer could be at particular risk of COVID-19, since they are often immunosuppressed by their therapy Assessing the risk-benefit ratio of potentially immunosuppressive treatment for patients with cancer with insufficient knowledge of this new disease and balancing individual and community benefits poses acute ethical dilemmas for oncologists Researchers provided the first guidelines for cancer patients treatment Individual treatment plans should be adjusted to minimise routine visits, procedures and tests Patients should be categorised into different priorities for receiving active cancer therapy during the pandemic Oncologists should consider changing intravenous treatments to subcutaneous or oral routes, as well as suspending radiation therapy or using hypofractionation In case of developing COVID-19 patients with cancer should be treated in the respiratory or intensive care units rather than in the oncology units Preventive measures and emergency plans to help patients should also be developed The COVID-19 pandemic has had a devastating impact on clinical research in haematology and oncology A dramatic reduction in the number of participants in current research and delays in planned haematology and oncology research, as well as adverse financial consequences and potential delays in the delivery of promising drugs to patients should be expected Regulatory agencies provided guidelines on managing clinical trials during the COVID-19 pandemic, emphasising the importance of pragmatism and flexibility in routine visits, procedures and tumour assessments and clearly documenting protocol deviations Ensuring patients’ safety during the pandemic is of primary priority Every trial participant should be contacted before the planned visit to ensure they don’t have any COVID-19 symptoms Laboratory and radiological assessments should be done at the closest to patient medical facility, and some investigational products, such as oral medications, should be delivered directly to patient to avoid hospital visits The COVID-19 pandemic has had a serious negative impact on both treatment of cancer patients and research in this area The support of all stakeholders is the only thing that can help ensure the best possible care for patients at this difficult time Коронавирусная инфекция 2019 г (COVID-19) быстро охватила весь мир Онкологические пациенты составляют особую группу риска, так как и само заболевание, и терапия, которую они получают, часто оказывают иммуносупрессивное действие Исследователи разных стран предоставили первые рекомендации по лечению онкологических больных в период пандемии Индивидуальные планы лечения должны корректироваться с целью минимизации рутинных посещений, процедур и исследований Врачам-онкологам необходимо рассмотреть перевод пациентов на пероральное и подкожное введение препаратов вместо инфузионного, а также приостановление лучевой терапии или использование гипофракционирования Также рекомендуется разработать профилактические меры и план действий в чрезвычайных ситуациях для оказания помощи пациентам Пандемия новой коронавирусной инфекции оказала разрушительное воздействие на проведение клинических исследований в области гематологии и онкологии, так как многие научные сотрудники и ресурсы были направлены в институты и больницы для оказания помощи возросшему потоку пациентов с COVID-19 Следует ожидать резкое сокращение числа участников текущих исследований, задержки планируемых запусков новых гематологических и онкологических исследований, а также пагубные финансовые последствия и возможные задержки поставок перспективных лекарств пациентам При проведении любых исследований в настоящее время обеспечение безопасности пациентов имеет первостепенное значение Пандемия COVID-19 оказала серьезное негативное воздействие и на лечение больных с онкологическими заболеваниями, и на исследования в этой области И лишь поддержка всех заинтересованных сторон поможет обеспечить помощь пациентам в это непростое врем

Oncolytic virotherapy in glioblastoma treatment: Progres and chalenges in clinical research (literature review)

Glial tumors comprise about 60 % of primary malignant brain tumors, and 70 % of them show morphological signs of high-grade cancer (High Grade Gliomas II, IV WHO 2016) [1, 2]. Despite a significant technical pre- and intraoperative progress as well as advances in radiotherapy and chemotherapy, the overall median survival is very low, being less than 20 months [3] and less than 12 months in patients with relapse [4]. Recent studies have shown that chemo- and radioresistance is due to the existence of cancer stem cells [5, 6]. Poor treatment outcomes require the development and implementation of new approaches to the treatment of highgrade gliomas. In recent years, increasing attention has been paid to the development of immunotherapeutic treatment approaches, including the development of oncolytic virotherapy. Tropism to target cancer cells, as well as various viral vectors, has been developed using methods of genetic engineering; synergism of viruses and adjuvant therapy has been studied. Despite extensive experimental studies of the mechanism of oncolysis [1], there are only a few reports on Phase I-II clinical trials. This review considers the most successful applications of oncolytic viruses in relation to glioblastoma in animal models and their translation into clinical practice in patients

Approximate modeling of spherical membranes

Spherical symmetry is ubiquitous in nature. It is therefore unfortunate that simulation of spherical systems is so hard and require complete spheres with millions of interacting particles. Here, we introduce a method to model spherical systems using revised periodic boundary conditions adapted to spherical symmetry. Method reduces computational costs by orders of magnitude, and is applicable for both solid and liquid membranes, provided the curvature is sufficiently small. We demonstrate the method by calculating the bending and Gaussian curvature moduli of single-layer and multilayer graphene. The method works with any interaction (ab initio, classical interactions), with any approach (molecular dynamics, Monte Carlo), and with applications ranging from science to engineering, from liquid to solid membranes, from bubbles to balloons.peerReviewe

Formation of the system of anti-stressor reactions as a non-specific basis for health and longevity

The proposed editorial article touches upon aspects of fundamental medicine associated with the discovery of systems of nonspecific adaptation reactions in the organism as a whole. It is shown that the key law of the organism's response to the actions of the external and internal environment consists in the dependence between the reaction quality and the quantity (measure, intensity) of an acting factor

Edge-stress -induced spontaneous twisting of graphene nanoribbons

We present a continuum model for spontaneous twisting of graphene nanoribbons driven by compressive edge stresses. Based on a geometrically nonlinear theory of plates, we identify scaling laws for the dependence of twist angles on ribbon width. Strikingly, we find the existence of a critical width below which a ribbon will not undergo spontaneous twisting, preferring an in-plane stretching mode instead. The model predictions are shown to be in excellent qualitative and quantitative agreement with density-functional tight-binding simulations. More generally, our model provides a unifying picture of twisting in graphene nanoribbons with different edge orientations and chemical functionalizations that have been reported recently in the literature.peerReviewe