Extremal states and coupling properties in electroelasticity.

Electroelastic materials possess properties most attractive for the design of smart devices and systems such as actuators and sensors. Typical polymers show changes in shape under the action of an electric field, and vice versa, together with fast actuation times, high strain levels and low elastic moduli. This paper deals with an Ogden model inspired framework for large deformation electroelasticity which, as a special case, can also be reduced to the modelling of transversely isotropic elasticity. Extremal (local) states are elaborated based on a coaxiality analysis, i.e. extremal states of energy are considered at fixed deformation and changing direction of electric field, respectively, fixed electric field and changing principal directions of deformation. This analysis results in extremal states when stresses and strain commutate, respectively, dielectric displacements and electric field are aligned. In order to further elaborate electromechanical coupling properties, the sensitivity of stresses with respect to electric field is analysed. This sensitivity is represented by a third-order tensor which, in general, depends on deformation and electric field. To illustrate this third-order tensor, a decomposition into deviators is adopted. Related norms of these deviators, together with the electromechanical coupling contribution to the augmented energy, are investigated for different states under homogeneous deformation and changing electric field direction. The analysis is considered to contribute to a better understanding of electromechanical coupling properties and extremal states in large deformation electroelasticity and by that, as a long-term goal, may contribute to the improved design of related smart devices and systems. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

Quantitative region-of-interest tomography using variable field of view.

In X-ray computed tomography, the task of imaging only a local region of interest (ROI) inside a larger sample is very important. However, without a priori information, this ROI cannot be exactly reconstructed using only the image data limited to the ROI. We propose here an approach of region-of-interest tomography, which reconstructs a ROI within an object from projections of different fields of view acquired on a specific angular sampling scheme in the same tomographic experiment. We present a stable procedure that not only yields high-quality images of the ROI but keeps as well the quantitative contrast on the reconstructed images. In addition, we analyze the minimum number of projections required for ROI tomography from the point of view of the band region of the Radon transform, which confirms this number must be estimated based on the size of the entire object and not only on the size of the ROI.

Indoor birch pollen concentrations differ with ventilation scheme, room location, and meteorological factors.

Indoor pollen concentrations are an underestimated human health issue. In this study, we measured hourly indoor birch pollen concentrations on 8 days in April 2015 with portable pollen traps in five rooms of a university building at Freising, Germany. These data were compared to the respective outdoor values right in front of the rooms and to background pollen data. The rooms were characterized by different aspects and window ventilation schemes. Meteorological data were equally measured directly in front of the windows. Outdoor concentration could be partly explained with phenological data of 56 birches in the surrounding showing concurrent high numbers of trees attaining flowering stages. Indoor pollen concentrations were lower than outdoor concentrations: mean indoor/outdoor (I/O) ratio was highest in a room with fully opened window and additional mechanical ventilation (.75), followed by rooms with fully opened windows (.35, .12) and lowest in neighboring rooms with tilted window (.19) or windows only opened for short ventilation (.07). Hourly I/O ratios depended on meteorology and increased with outside temperature and wind speed oriented perpendicular to the window opening. Indoor concentrations additionally depended on the previously measured concentrations, indicating accumulation of pollen inside the rooms even after the full flowering period.

Climate threats on growth of rear-edge European beech peripheral populations in Spain.

European beech (Fagus sylvatica L.) forests in the Iberian Peninsula are a clear example of a temperate forest tree species at the rear edge of its large distribution area in Europe. The expected drier and warmer climate may alter tree growth and species distribution. Consequently, the peripheral populations will most likely be the most threatened ones. Four peripheral beech forests in the Iberian Peninsula were studied in order to assess the climate factors influencing tree growth for the last six decades. The analyses included an individual tree approach in order to detect not only the changes in the sensitivity to climate but also the potential size-mediated sensitivity to climate. Our results revealed a dominant influence of previous and current year summer on tree growth during the last six decades, although the analysis in two equally long periods unveiled changes and shifts in tree sensitivity to climate. The individual tree approach showed that those changes in tree response to climate are not size dependent in most of the cases. We observed a reduced negative effect of warmer winter temperatures at some sites and a generalized increased influence of previous year climatic conditions on current year tree growth. These results highlight the crucial role played by carryover effects and stored carbohydrates for future tree growth and species persistence.

X-ray scattering experiments with high-flux X-ray source coupled rapid mixing microchannel device and their potential for high-flux neutron scattering investigations.

Small-angle X-ray scattering provides global, shape-sensitive structural information about macromolecules in solution. Its extension to time dimension in the form of time-resolved SAXS investigations and combination with other time-resolved biophysical methods contributes immensely to the study of protein dynamics. TR-SAXS can also provide unique information about the global structures of transient intermediates during protein dynamics. An experimental set-up with low protein consumption is essential for an extensive use of TR-SAXS experiments on protein dynamics. In this direction, a newly developed 20-microchannel microfluidic continuous-flow mixer was combined with SAXS. With this set-up, we demonstrate ubiquitin unfolding dynamics after rapid mixing with the chaotropic agent Guanidinium-HCl within milliseconds using only ∼ 40 nanoliters of the protein sample per scattering image. It is suggested that, in the future, this new TR-SAXS platform will help to increase the use of time-resolved small-angle X-ray scattering, wide-angle X-ray scattering and neutron scattering experiments for studying protein dynamics in the early millisecond regime. The potential research field for this set-up includes protein folding, protein misfolding, aggregation in amyloidogenic diseases, function of intrinsically disordered proteins and various protein-ligand interactions.

A Boolean Network Approach to Study the Mechanism Associated with Inflammatory Response Induced by Porphyromonas gingivalis.

Anaerobic Porphyromonas gingivalis is a rod-shaped bacterium and is a primary agent of periodontal inflammation and thus periodontitis. This bacterium disturbs the normal flora of the oral cavity and causes dysbiosis. Databases including Google Scholar Scopus and PubMed were employed to find the evidence by using keywords like 'Porphyromonas gingivalis,' 'Boolean network,' 'inflammatory response and Porphyromonas gingivalis,' 'inflammation and Porphyromonas gingivalis. Only articles that reviewed the role of Porphyromonas gingivalis in oral inflammation were selected. Porphyromonas gingivalis promotes and reorganizes host immune systems against normal host flora, which causes a dysbiotic state. A reorganized immune system induces dysbiosis and periodontitis. Specifically, the role of the C5a receptor in the complement system is vital in this mechanism. P. gingivalis can change the metabolic pathways of phagocytic cells without impeding inflammation. Toll-like receptor and complement signaling are inverted by Porphyromonas gingivalis, which aids them in overcoming immunological responses. However, they sustain the inflammation process, which promotes dysbiosis. Instead of a subjective approach, a systems perspective is required to comprehend this intricate process. A Boolean network is a system approach that seems to be a better approach to understanding this complicated interaction process of Porphyromonas gingivalis with the immune system and inflammation. In short, attempts to understand the complex process using the Boolean network will ultimately help in the early detection of periodontitis, and immediate treatment can prevent soft tissue destruction and dentition loss.

Capturing dynamics with Eiger, a fast-framing X-ray detector.

Eiger is the next-generation single-photon-counting pixel detector following the widely used Pilatus detector. Its smaller pixel size of 75 µm × 75 µm, higher frame rate of up to 22 kHz, and practically zero dead-time (~4 µs) between exposures will further various measurement methods at synchrotron sources. In this article Eiger's suitability for X-ray photon correlation spectroscopy (XPCS) is demonstrated. By exploiting its high frame rate, complementary small-angle X-ray scattering (SAXS) and XPCS data are collected in parallel to determine both the structure factor and collective diffusion coefficient of a nano-colloid suspension. For the first time, correlation times on the submillisecond time scale are accessible with a large-area pixel detector.

Toxic Metals Exposure and APOE4 Gene Variant in Cognitive Decline Disorders.

Neurodegenerative disorders are those which affect cognitive functions. Misfolding of proteins especially apolipoprotein E is a key genetic factor involved in several cognitive impairments. Increasing evidence also described the toxic effects of metals, generated by both nature and humans, on the development of neurological disorders. Understanding of interaction between toxic metals and apolipoprotein E protein in cognitive decline diosrders would provide alternative treatment options. Google Scholar and PubMed database were used to search the articles using different search terms like 'toxic metals', 'cognitive decline', 'Apolipoprotein E', "neurodegenerative disorders" and "metals neurotoxicity". Only those papers were included that discussed the metal exposure-apolipoprotein association in the development of cognitive decline disorders. Heavy metals are particularly recognized as a major source of neurotoxicity. These toxic metals can interact with genetic factors and play important role in disease etiology. Understanding the underlying mechanism of this interaction could provide tremendous benefits to treat cognitive decline disorders. In this study, the role of the apolipoprotein E4 gene in the development of cognitive disease conditions and their phenotypes has been discussed thoroughly which leads to the accumulation of amyloid-beta fibrils. This exploratory study revealed novel hypothetical findings which might contribute to the understanding of the neurotoxic effects of chronic toxic metals exposure and possibly improve our knowledge on the molecular mechanisms linking metal exposure to cognitive decline disorder risk.

A Review on Metabolic Paradoxes and their Impact on Metabolism.

The current review paper portrays the important link of different nutrients like trace elements, proteins, fatty acids, vitamins, and amino acids with the immune system as well as information related to metabolic paradoxes. Optimum working of the metabolic system is essential because it gives various types of supplements to the human body and aid in chemical pathways. Here related data have been retrieved from two databases i.e., PubMed and Google scholar to grasp detailed knowledge about micronutrients and nutrients as well as their association in the metabolic system. Like protein play important role in the normal development of different immune components, amino acids including alanine, Arginine, and glutamic acid properly control the movement of neutrophils, macrophages, and cytokines. While fatty acids act as an anti-inflammatory agent because they possess the ability to inhibit the expression of the MHC class. Apart from these, many essential molecules like uric acid, proteins, calcium, lanolin are also obtained as end products after catabolic and anabolic reactions, and it was found that the uric acid paradox has a cancer inhibitory role. Additionally, TGF and IL-6 paradoxes have a role in the development of tumors, the onset of diabetes, and low-grade inflammatory disorders respectively. However, the entire functioning of metabolic processes depends upon daily diet because humans get the important nutrient from the diet which further vital role in the immune system. Moreover, it was also observed that calcium paradox is related to heart disorders because high calcium accumulation leads to cardiac disorders. Thus, the complete knowledge about these essential components as well as metabolic paradoxes is very important due to their antagonistic role to plan better and improved therapeutic strategies for various diseases.

Toxic Metal -Mediated Neurodegradation: A Focus on Glutathione and GST Gene Variants.

Increasing pieces of evidence have supported those chemicals from industrial, agricultural wastes and organoleptic activities play important role in the development of neurological disorders. The frequency of neurological disorders is increased to a much extent in recent years with the advancements in science and technology. Google Scholar, PubMed, and Scopus databases were selected to search the relevant information by using keywords including "Heavy metals", "Neurotoxicity", "Glutathione", "Glutathione AND Neurodegenerative disorders" etc. Heavy metals are particularly recognized as a major resource of toxicities during the stage of early pregnancy where a fetus gets exposed to them from maternal activities and circulation. As infants have a weak immune system and cannot respond to the specific challenge as faced by the body during mercury, zinc, iron, and cadmium exposure. Daily diet and drinking habits in addition to industrial activities also form a major field of study under investigation. This study aims to investigate the role of these metals in the accumulation of pollutants in the brain, liver, and kidneys hence leading to serious consequences. Moreover, their prevalence in teenagers that are under the age of ten years is being observed that leads them to learn, writing, and intellectual abilities. Males are more affected due to their hormonal differences. The role of the GST gene in the development of cognitive conditions and its phenotypes has been discussed thoroughly in this review. The mutations of GST lead to the accumulation of peroxides and superoxides which exacerbate oxidative damage to cells. Binding of toxic metals to GSH genes and the role of glutathione transferase genes is was demonstrated in this review.

Mediated interactions between rigid inclusions in two-dimensional elastic or fluid films.

Interactions between rigid inclusions in continuous three-dimensional linearly elastic solids and low-Reynolds-number viscous fluids have largely been quantified in the past. Prime example systems are given by functionalized elastic composite materials or fluid colloidal suspensions. Here, we address the significantly less frequently studied situation of rigid inclusions in two-dimensional elastic or low-Reynolds-number fluid films. We concentrate on the situation in which disklike inclusions remain well separated from each other and do not get into contact. Specifically, we demonstrate and explain that the logarithmic divergence of the associated Green's function is removed in the absence of net external forces on the inclusions, in line with physical intuition. For instance, this situation applies when only pairwise mutual interactions between the inclusions prevail. Our results will support, for example, investigations on membranes functionalized by appropriate inclusions, both of technical or biological origin, or the dynamics of active microswimmers in appropriately prepared thin films.

Increasing Efficacy of Covid-19 Vaccines by Lifestyle Interventions.

COVID-19 caused a serious threat to the world population as it spread worldwide rapidly. Existing medicines and vaccines could not cure and control this deadly disease. In this regard, several vaccines have been proposed and designed to control this infection's spread effectively. Along with these vaccines, the general population should adopt specific lifestyle interventions to strengthen their immune system and combat deadly viruses. We used Google Scholar and PubMed databases to find the related information using key terms such as 'COVID-19', 'COVID-19 AND Vaccine efficacy', 'Lifestyle intervention AND COVID-19', and "Lifestyle intervention AND Vaccines," etc. Only articles that discussed the interactions between lifestyle intervention and the efficacy of COVID-19 vaccines were selected for this study. Several previous clinical trials and scientific observations with influenza, polio, and other viral vaccines have demonstrated that vaccine response varies across individuals for antibody titer, independent of vaccine antigenicity. This different vaccine response observed among individuals is attributed to several factors such as dietary and nutritional habits, physical activity, stress and sleep deprivation, deficiency of micronutrients (minerals, vitamins), gut microbiota composition, immunosenescence, smoking, and drinking habits. Although there is not much information about COVID-19 vaccine efficacy and lifestyle interventions, experience with other vaccines can undoubtedly be used to suggest lifestyle interventions to improve COVID-19 vaccine efficacy. These lifestyle interventions may boost antibody responses against COVID-19 vaccines, leading to higher protection from the disease, especially among elderly and immunocompromised people. In conclusion, the present review attempts to understand the role of various nutritional and psychological factors that lead to poor vaccine response and suggests specific nutritional and psychological interventions that can enhance vaccine efficacy and improve immune response against COVID-19 vaccines.

Molecular X-ray computed tomography of myelin in a rat brain.

In this work we demonstrate the feasibility of applying small-angle X-ray scattering computed tomography (SAXS-CT) for non-invasive molecular imaging of myelin sheaths in a rat brain. Our results show that the approach yields information on several quantities, including the relative myelin concentration, its periodicity, the total thickness of the myelin sheaths, and the relative concentration of cytoskeletal neurofilaments. For example the periodicity of the myelin sheaths varied in the range from 17.0 to 18.2 nm around an average of 17.6 (±0.3) nm. We believe that imaging, i.e., spatially resolved measuring these quantities could provide general means for understanding the relation to a number of neurodegenerative diseases.

Lifestyle Genetics-Based Reports in the Treatment of Obesity.

Obesity becomes a chronic disease due to the increasing number of mortality and morbidity cases around the world. In most regions, chronic illnesses, such as obesity, are important sources of morbidity and mortality. Due to a lack of effective strategies for prevention and management, the adverse effects of obesity and related diseases on health continue to be a serious problem. Relevant information was searched from Google Scholar, Scopus, and PubMed using such different terms as "Obesity", "Obesity Management", "Obesity AND Physical activity", "Obesity AND Genetics", "Obesity AND Diet", and "Obesity AND Nutrigenomics". Obesity is characterized by a complex interaction of hereditary and lifestyle factors, which includes food. Diet is an environmental element that plays an important and considerable role in the management of health and reduces the risk of obesity and its comorbidities. Changes in lifestyle patterns not only help burn extra calories but also prevent the development of obesity via its modulating effect on genetic factors. Different people respond differently to an obesogenic environment. The notion of nutrigenetics emerged as a result of various genetic variations that may explain this heterogeneity. Nutritional genomics, also known as nutrigenetics, is the study that investigates and analyses gene variations linked to varied responses to certain foods; moreover, it links this variation to diseases, such as obesity. As a result, tailored nutrition advice based on a person's genetic profile may improve the outcomes of a specific dietary strategy and offer a novel dietary strategy to improve life quality and preventing obesity. This study concluded that physical activity and dietary interventions play an effective role in the management of obesity. Moreover, understanding of the function of the most prominent obesity-related genes, as well as the interaction between nutrition and gene expression, will help researchers design personalized treatment strategies for humans.

Oral Aphthous: Pathophysiology, Clinical Aspects and Medical Treatment.

Oral aphthosis is a painful inflammatory process of the oral mucosa. Oral aphthous can appear alone or secondary to numerous distinct disease processes. If recurrence occurs frequently, it is called recurrent aphthous stomatitis. The pathophysiology of oral aphthous ulcers remains unclear but various bacteria are part of its microbiology. Three morphological types hold great importance in literature because these types help manage the illness properly. Google Scholar and PubMed databases were used to retrieve the relevant data and information. Different keywords including "Aphthous", "Aphthosis", "Canker sores", "Aphthous stomatitis", "Aphthous ulcer causes", "Aphthous ulcer AND Microbiota" and "Aphthous ulcer AND treatment". The causes for oral aphthous ulcerations are widespread and ranges from localized trauma to rare syndromes, underlying intestinal disease, or even malignant disease processes. A detailed history and thorough examination of systems can assist the physician or dermatologist in defining whether it is related to a systemic disease process or truly idiopathic. Management of oral aphthous ulcers is challenging. For oral aphthous or recurrent aphthous ulcers from an underlying disease, topical medications are preferred due to their minimum side effects. Systemic medications are necessary if the disease progresses. Within the limitation of research and literature provided, it is safe to say that topical corticosteroids are the first line of treatment. Herein, the author discusses the pathophysiology, types, causes, diagnosis, and appropriate treatment ladder of oral aphthous stomatitis as described in the literature.

Impact of urbanization on the proteome of birch pollen and its chemotactic activity on human granulocytes.

BACKGROUND: Epidemiologic studies reveal a dramatic increase in allergies in the last decades. Air pollution is considered to be one of the factors responsible for this augmentation. The aim of this study was to analyze the impact of urbanization on birch pollen. The birch pollen proteome was investigated in order to identify differences in protein abundance between pollen from rural and urban areas. The allergenicity of birch pollen from both areas was evaluated by assessing its chemotactic potency as well as its protein and allergen contents. METHODS: Difference gel electrophoresis (DIGE) was used to analyze the pollen proteome. The chemotactic activity of aqueous pollen extracts was determined by migration assays of human neutrophils. RESULTS: DIGE revealed 26 differences in protein spot intensity between pollen from urban and rural areas. One of these proteins was identified by de novo sequencing as the 14-3-3 protein, which resembles a stress-induced factor in other plant species. Furthermore, extracts from pollen collected in urban areas had higher chemotactic activity on human neutrophils compared to pollen from rural sites. CONCLUSIONS: The present study points to an impact of air pollution on allergen carrier proteome and release of chemotactic substances. The increment in proinflammatory substances such as pollen-associated lipid mediators might contribute to the described urban-rural gradient of allergy prevalence. Furthermore, our study suggests that allergenicity is determined by more than the sole allergen content.

Association of rheumatoid arthritis with Mdm2 SNP309 and genetic evidence for an allele-specific interaction between MDM2 and p53 P72R variants: a case control study.

OBJECTIVE: This study examines two common, functional, single nucleotide polymorphisms (SNP) in the genes coding the human homolog of murine-double-minute-2 (MDM2) and p53 in patients with rheumatoid arthritis (RA) based on the hypothesis that p53 may be an important negative regulator of the pro-inflammatory transcription factor nuclear factor kappa b (NFKappaB). METHODS: Genomic DNA was obtained from 221 patients with RA who fulfilled at least 4 ACR criteria and from 521 healthy controls. Mdm2 SNP309 and p53 P72R were genotyped by polymerase chain reaction and restriction enzyme analysis. RESULTS: In RA patients the frequencies of the mdm2 SNP309 G allele and both G-containing genotypes were significantly reduced (G allele: OR: 0.75, 95% CI: 0.59-0.95, p=0.016; genotype TG: OR: 0.71, 95% CI: 0.50-1.00; genotype GG: OR. 0.58, 95% CI: 0.34-0.99; both: p=0.049). Concerning p53 P72R, no differences in allele or genotype frequencies were detected. A combined analysis of both polymorphisms revealed a significant interaction between them (p=0.046). In individuals carrying >1 p53 72R allele, MDM2 had a protective effect, whereas in individuals homozygous for p53 72P, MDM2 had the opposite effect. CONCLUSION: The function of MDM2 depends on the p53 P72R genotype, resulting in either an increased or reduced risk for RA. We suggest that in most cases MDM2 stabilizes the conformation of p53, whereas in p53 PP-positive subjects MDM2 supports the degradation of p53.

Response of prestretched nematic elastomers to external fields.

We investigate the response of prestretched nematic side-chain liquid single-crystal elastomers to superimposed external shear, electric, and magnetic fields of small amplitude. The prestretching direction is oriented perpendicular to the initial nematic director orientation, which enforces director reorientation. Furthermore, the shear plane contains the direction of prestretch. In this case, we obtain a strongly decreased effective shear modulus in the vicinity of the onset and the completion of the enforced director rotation. For the same regions, we find that it becomes comparatively easy to reorient the director by external electric and magnetic fields. These results were derived using conventional elasticity theory and its coupling to relative director-network rotations.

Functional xylem anatomy of aspen exhibits greater change due to insect defoliation than to drought.

The study of tree rings can reveal long-term records of a tree's response to the environment. This dendroecological approach, when supplemented with finer-scale observations of the xylem anatomy, can provide novel information about a tree's year-to-year anatomical and hydraulic adjustments. Here we use this method in aspen (Populus tremuloides Michx.) to identify xylem response to drought and insect defoliation. Surprisingly, we found that precipitation influenced vessel diameter mostly in the trees' youth, while this correlation was less pronounced at maturity. This is likely due to a reduction in stress the stand experiences as it ages, and reflects an ability to mediate drought stress as trees mature. Defoliation events caused consistent and profound changes in fiber anatomy likely leading to reduced structural support to vessels. We therefore expect that in years of defoliation trees may be vulnerable to drought-induced cavitation when leaf area recovers. This study highlights how the inclusion of cellular level measurements in tree ring studies provides additional information on how stress events may alter tree functioning through alterations in structure.

Predicting the start, peak and end of the Betula pollen season in Bavaria, Germany.

Betula pollen is frequently found in the atmosphere of central and northern Europe. Betula pollen are health relevant as they cause severe allergic reactions in the population. We developed models of thermal requirements to predict start, peak and end dates of the Betula main pollen season for Bavaria (Germany). Betula pollen data of one season from 19 locations were used to train the models. Estimated dates were compared with observed dates, and the errors were spatially represented. External validation was carried out with time series datasets of 3 different locations (36years in total). RESULTS: The temperature requirements to detonate the main pollen season proved non-linear. For the start date model (error of 8,75days during external validation), daily mean temperatures above a threshold of 10°C from 28th of February onwards were the most relevant. The peak model (error of 3.58days) takes into account mean daily temperatures accumulated since the first date of the main pollen season in which the daily average temperature exceeded 11°C. The end model (error of 3.75days) takes into account all temperatures accumulated since the start of the main pollen season. CONCLUSION: These models perform predictions that enable the allergic population to better manage their disease. With the established relationship between temperatures and pollen season dates, changes in the phenological behaviour of Betula species due to climate change can be also estimated in future studies by taking into account the different climate scenarios proposed by previous climate change studies.