Extrinsic Modification Research Articles

A review on interplay between small RNAs and oxidative stress in cancer progression.

Oxidative stress has been known to be the underlying cause in many instances of cancer development. The new aspect of cancer genesis that has caught the attention of many researchers worldwide is its connection to non-coding RNAs (ncRNAs). ncRNAs may not be protein coding, but in light of the more recent discovery of their wide range of functions, the term 'dark matter of the genome' has been rendered inapplicable. There is an extensive mention of colon cancer as an example, where some of these ncRNAs and their manipulations have seen significant progress. As of now, the focus is on discovering a non-invasive, cost-effective method for diagnosis that is easier to monitor and can be conducted before visible symptoms indicate cancer in a patient, by which time it may already be too late. The concept of liquid biopsies has revolutionized recent diagnostic measures. It has been possible to detect circulating parts of the cancer genome or other biomarkers in the patients' bodily fluids, resulting in the effective management of the disease. This has led these ncRNAs to be considered effective therapeutic targets and extrinsic modifications in several tumor types, proven to be effective as therapy. However, there is a vast scope for further understanding and pertinent application of our acquired knowledge and expanding it in enhancing the utilization of ncRNAs for a better prognosis, quicker diagnosis, and improved management of cancer.This review explores the prognosis of cancer and related mutations by scrutinizing small ncRNAs in the disease.

Effects of foot orthoses with a lateral bar on the biomechanics of the lower limb in individuals with cavus feet during walking

Foot orthoses (FOs) are prescribed to treat and prevent many lower limb musculoskeletal disorders (Bonanno et al., 2017). Extrinsic modifications are regularly added to FOs in clinical practice to ...

Determinants of offspring sex in kangaroos: a test of multiple hypotheses

Abstract When the fitness costs and benefits of sons and daughters differ, offspring sex ratio manipulation could be an important reproductive tactic. We explored the effects of environment and maternal caring ability on offspring sex to test four adaptive sex ratio modification hypotheses: the extrinsic modification hypothesis (EMH), carrying capacity hypothesis (CCH), Trivers-Willard hypothesis (TWH), and cost-of-reproduction hypothesis (CRH). The EMH and CCH propose that environmental conditions shape offspring sex ratios, directly or in interaction with maternal condition. The TWH and CRH predict a positive relationship between maternal condition and production of the costlier sex. The TWH predicts that mothers with superior caring ability should produce more of the sex that can provide the greatest fitness returns from additional maternal allocation, and the CRH proposes that females with limited caring ability should reduce fitness costs by producing the cheaper sex. Repeated measures on 83 known-age eastern gray kangaroos, polygynous marsupials with strong sexual dimorphism, revealed that offspring sex ratio was independent of per capita forage, supporting neither the EMH nor CCH, but was dependent on maternal mass, consistent with the TWH and CCH. Our results, however, cannot clearly identify the ultimate cause of the relationship between maternal mass and greater production of sons. One of the three assumptions of the TWH could not be verified, and mothers of sons suffered only marginal additional fitness costs. Sex ratios in higher vertebrates are likely not solely explained by factors dependent on maternal control.

MXenes for electromagnetic interference shielding: Experimental and theoretical perspectives

MXenes are two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides with unique intrinsic properties, including excellent electrical conductivity, 2D sheet morphology, lightweight, flexibility, tunable surface chemistry, and easy solution processability, thus attracting considerable attention as electromagnetic interference (EMI) shielding materials. In this review, we demonstrate, from both experimental and theoretical perspectives, that the outstanding EMI shielding performance of MXenes is determined not only by its intrinsic properties but also by extrinsic modifications such as the introduction of dielectric inclusions, pores, or other designed structures. This review provides guidance for the efficient application of available resources, as well as insights into the challenges that should be addressed to develop more efficient and economical MXene based shielding materials for the advanced electronics industry of the future.

Textile‐Based Strain Sensor for Human Motion Detection

Human motion analysis consists of real‐time monitoring and recording of human body's kinematics. It is very essential to track ambulatory and daily‐life human motion, which is crucial for many applications and disciplines. Electronic textiles (e‐textiles) afford a valid alternative to traditional solid‐state sensors due to their merits of low cost, lightweight, flexibility, and feasibility to fit various human bodies. In this mini‐review, textile‐based sensor platforms and human motion analysis are well discussed in Section 1. Second, theoretical principles of textile‐based strain sensors are introduced including resistive, capacitive, and piezoelectrical sensors. Section 3 focuses on various types of textile materials that are functionalized as sensing systems by intrinsic or extrinsic modifications. Section 4 summaries various types of e‐textile‐based strain sensors for human motion analysis. The final two sections mainly present perspectives and challenges, and conclusions, respectively.

Structural evolution dynamics in fusion of sumanenes and corannulenes: defects formation and self-healing mechanism

The fusion processes of structures consisting of various combinations between sumanene and corannulene, leading to the formation of graphene nanoribbons (GNRs) under heating are simulated by density-functional-based tight-binding molecular dynamics. Distinct stages are unraveled in the course of GNR formation. Firstly, the carbon fragments coalescence into highly strained framework. Secondly, structural reconstruction invokes breaking most strained bonds to form a GNR structure containing numerous defects. Lastly, defects are remedied by the delicate ‘edge-facilitated self-healing’ process through two synergized edge-related effects: elevated mobility of defects and promoted structure reconstructions owing to the remarkable dynamics associated with edges. Importantly, detailed dynamics in the course of forming GNRs with defects and grain boundaries simulated in this work is valuable to provide better understanding at the atomistic scale of defect formation as well as self-healing in the context of the sp2 carbon network. In particular, edges play important roles in not only generating Stone–Wales (SW), 5-8-5 types of defects, 8-5-5-8 and pentagon–heptagon grain boundaries. In addition, our simulations predict the existence of one novel defect, coined as the Inverse SW defect, which is to be confirmed in future experimental studies. This study of dynamic structural evolution reveals that edges are prone to intrinsic and extrinsic modifications such as atomic-scale defects, structural distortions and inhomogeneity.

Comparison of Single-Phase and Two-Phase Composite Thermal Barrier Coatings with Equal Total Rare-Earth Content

Rare-earth zirconates have been the focus of advanced thermal barrier coating research for nearly two decades; however, their lack of toughness prevents a wide-scale adoption due to lack of erosion and thermal cyclic durability. There are generally two methods of improving toughness: intrinsic modification of the coating chemistry and extrinsic modification of the coating structure. This study compares the efficacy of these two methods for a similar overall rare-earth content via the air plasma spray process. The extrinsically toughened coatings were comprised of a two-phase composite containing 30 wt.% Gd2Zr2O7 (GZO) combined with 70 wt.% of a tougher t′ low-k material (ZrO2-2Y2O3-1Gd2O3-1Yb2O3; mol.%), while a single-phase fluorite with the overall rare-earth content equivalent to the two-phase composite (13 mol.% rare-earth) was utilized to explore intrinsically toughened concept. The coatings were then characterized via x-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy, and their performance was evaluated via erosion, thermal conductivity, thermal annealing (500 h), and thermal cycling. It was shown that the extrinsic method provided an improved erosion and thermal conductivity response over the single phase, but at the expense of high-temperature stability and cyclic life.

MnO2 nanomaterials for flexible supercapacitors: performance enhancement via intrinsic and extrinsic modification.

Increasing power and energy demands for next-generation portable and flexible electronics have raised critical requirements (flexibility, stretch-ability, environmental friendliness, lightweight, etc.) for the energy storage devices. Flexible supercapacitors (SCs), as one of the most promising next-generation energy storage devices, have stimulated intensive interest owing to their outstanding features including small size, low weight, ease of handling, excellent reliability, and high power density. Manganese oxide (MnO2), has attracted much interest in the development of flexible SCs with high electrochemical performance. Yet, the poor electronic and ionic transport in MnO2 electrodes still limits its promotion in practical applications. This review aims to describe the recent progress in the application of MnO2 materials in the development of flexible SCs and summarizes the intrinsic modification of MnO2via crystallinity, crystal structure, and oxygen vacancy introduction and the extrinsic modification of MnO2via non-three-dimensional (3D) and 3D flexible conductive scaffolds for high performance flexible SCs. Moreover, we also discuss briefly on the current challenges, future directions, and opportunities for the development of high-performance MnO2 based flexible SCs.

CAR T Cells for Solid Tumors

Chimeric antigen receptor (CAR) T cells face a unique set of challenges in the context of solid tumors. To induce a favorable clinical outcome, CAR T cells have to surmount a series of increasingly arduous tasks. First, they have to be made specific for an antigen whose expression clearly demarcates tumor from normal tissue. Then, they must be able to home and penetrate the desmoplastic stroma that surrounds the tumor. Once within the tumor, they must expand, persist, and mediate cytotoxicity in a hostile milieu largely composed of immunosuppressive modulators. Whereas a seemingly herculean task, all of the aforementioned requirements can potentially be met effectively through both intrinsic and/or extrinsic modifications of CAR T cells. In this review, we delineate the barriers imposed by solid tumors on CARs and strategies that have and should be undertaken to improve therapeutic response.

Controlled Introduction of Anelasticity in Plasma‐Sprayed Ceramics

Recent studies on the mechanical compliance measurements of plasma‐sprayed ceramic coatings have revealed anelastic response, i.e. the stress–strain relations are nonlinear and hysteretic, collectively. The anelasticity stems from the “brick” layered assemblage of spray‐deposited droplets along with the presence of porosity and other geometric discontinuities. This anelastic response is reproducible and can provide a quantitative description on the mechanical properties of the sprayed ceramic coating. In this paper, we have examined strategies to manipulate and control these anelastic characteristics through plasma spray processing parameters as well as through extrinsic modifications of the defect interfaces. Plasma‐sprayed ceramic coatings are fabricated under various conditions and their unique anelastic parameters are computed. These results reveal that the novel properties are tunable via process and material manipulation, opening up opportunities for microstructural design and optimization of mechanical compliance in industrially relevant coating systems.

Climate and maternal effects modify sex ratios in a weakly dimorphic marsupial

There is growing evidence that the sex ratios of wild vertebrate populations are determined by mechanisms that are directly influenced by environmental characteristics. The Trivers–Willard (TWH) and extrinsic modification (EMH) hypotheses postulate differing determinants of mammalian offspring sex ratios. TWH states that mothers allocate resources according to their current condition and sex-specific offspring costs. EMH states that environmental forces that affect maternal condition determine offspring sex ratios, independently of maternal tactics of sex-biased allocation. We statistically assessed support for each of these hypotheses using long-term life histories of the allied rock-wallaby, Petrogale assimilis; a continuously breeding, polygynous, weakly dimorphic marsupial. We showed that birth sex ratios were equal and independent of maternal and environmental conditions. However, secondary sex ratios were male-biased under good environmental conditions and for high quality mothers or mothers in good condition. Sex differences in offspring survival contributed to these biases: (1) environmental conditions strongly influenced survival to pouch emergence (in support of EMH) and (2) maternal quality affected survival to the end of maternal care (in support of TWH). Environmental effects on survival were more important than maternal factors over the entire period of maternal care and contributed most to male-biased sex ratios at pouch emergence. In contrast, maternal mass was the best predictor of sex ratios at the end of maternal care—the life history stage where offspring body mass differed between the sexes.

Adjustment of Reproductive Investment and Offspring Sex Ratio in White-tailed Deer (Odocoileus virginianus) in Relation to Winter Severity

Both density-dependent factors and environmental stochasticity can impact the dynamics of free-ranging populations. The pathways through which these factors influence population dynamics can be complex and may be immediate or lagged, and cumulative effects of environmental factors have been reported. We examined the effects of the severity (snow depth and persistence and winter rainfall) of the current and previous winters on the probability that female adult and yearling white-tailed deer (Odocoileus virginianus) would produce a fetus, and that adult females would produce a male fetus. We used logistic regression and Akaike’s information criterion to select the best models from a set of 11 a priori candidate models. The severity of the winter 1 year before gestation negatively impacted the probability that both adults and yearlings would produce a fetus. There was no evidence that the probability of yearlings or adults producing a fetus was affected by winter conditions while gestating. Further, there was no evidence that the severity of the winter during which a yearling was gestated affected its probability of producing a fetus as a yearling. As the severity of the winter of gestation increased, the probability of producing a male decreased, consistent with both the Trivers‐Willard sex ratio adjustment hypothesis and the extrinsic modification hypothesis. We suggest that both the decreased probability of reproduction after severe winters and the variation in fetal sex ratio may ultimately increase lifetime fitness if they lead to the production of the fittest offspring given the available maternal resources.

Litter size and fetal sex ratio adjustment in a highly polytocous species: the wild boar

For species in which reproductive success is more variable in one sex than the other, the Trivers and Willard model (TWM) predicts that females are able to adjust their offspring sex ratio. High-quality mothers should provide greater investment to one sex than the other. Previous tests of the TWM have been inconsistent, and whether the TWM applies to species with several offspring per litter is unclear due to possible trade-offs between size, number, and sex of the offspring. Williams’ model (WM) accounts for confounding effects of these trade-offs on sex ratio variation. Lastly, the ‘‘extrinsic modification hypothesis’’ predicts changes in offspring sex ratio in relation to climatic conditions and population density. Using wild boar as a model, we tested 1) whether the WM fitted observed sex ratio variation and 2) whether sex ratio variations were related to maternal attributes (test of the TWM) and/or to resource availability (test of the extrinsic modification hypothesis). Females adjusted their litter size rather than their litter composition, so that the WM was not supported. Likewise, changes in resource availability did not influence the fetal sex ratio, so that the extrinsic modification hypothesis was not supported. The fetal sex ratio was negatively related to increasing litter size, providing some support for the TWM. Sex ratio was male biased for litter sizes up to 6 and then became female biased in larger litters. Our results provide the first case study showing marked changes in sex ratio in relation to litter size in a large mammal. Key words: litter size, primary sex ratio, sex ratio variation, Sus scrofa scrofa, Trivers and Willard model, Williams model. [Behav Ecol]

Sex ratio variation in reindeer Rangifer tarandus: a test of the extrinsic modification hypothesis

Evolutionary theories based on adaptive modification of maternal investment are generally suggested to explain variation in offspring sex ratios, but general concordance with empirical data is rare. Recently, factors beyond the control of the mother, such as density and climate, were reported to affect offspring sex ratios, and the extrinsic modification (EM) hypothesis has been advanced to explain such variation. The EM hypothesis states that offspring sex ratios in sexually dimorphic vertebrates may vary with extrinsically induced changes in maternal condition during pregnancy. We investigated sex ratio variation and inter‐cohort calf live weight variation in 5,509 reindeer Rangifer tarandus calves during an eight‐year period. Using separate models, we also tested whether offspring sex ratio covaried with density, and, respectively, summer weather before conception and winter weather (measured by the North Atlantic Oscillation (NAO)) when calves were in utero. Offspring sex ratios in mid‐July differed from parity only in one year. Calf live weight varied among cohorts and males were heavier than females. The proportion of male calves in the herd decreased significantly with an increasing NAO index when calves were in utero. Density in the year of birth only affected calf sex ratios by increasing the negative effects of the NAO index. The proportion of males in the herd also declined with increasing summer temperature, summer precipitation, and density in the year of conception, suggesting potential for pre‐conception environmental effect. Because the reported environmental variables affected negatively the proportion of male calves in the herd, we suggest that their effects may be associated with nutritional stress caused to the mother before conception, which have not been shown previously, and during pregnancy. Evidence of extrinsic sex ratio adjustment was conclusive and our findings therefore support the EM hypothesis of sex ratio variation.

Extrinsic Modification of Vertebrate Sex Ratios by Climatic Variation

Evidence for the influences of climate on early development, maternal condition, and offspring viability in terrestrial vertebrates suggests that climatic change has the potential to induce variation in offspring sex ratios in such organisms. Using long-term data at individual and population levels, we investigated the influence of global climatic variation, as a result of the North Atlantic Oscillation (NAO), on offspring sex ratios of red deer in Norway. The state of the NAO during the fetal development of hinds influenced the mass of their sons, but not daughters, and increasingly warmer and snowy winters led to increasingly male-biased offspring sex ratios, independently of changes in the mean age of hinds. Moreover, hinds that were themselves born following warm, snowy winters were smaller as adults, produced significantly lighter sons, and tended to produce more sons than hinds born following cold, dry winters. In light of the fact that these observations defy explanation according to previous hypotheses of adaptive modification of offspring sex ratios, we present the extrinsic modification hypothesis, which suggests that sex ratios may evolve in variable environments through natural selection independently of maternal strategies of sex allocation.

Extrinsic Modification of Vertebrate Sex Ratios by Climatic Variation

Extrinsic Modification of Vertebrate Sex Ratios by Climatic Variation

The Effect of Extent of Distribution on Speciation

1. Extent of distribution has a direct influence on the speciation of the group concerned in this way, that as the range of a group of animals is extended, the species increase out of proportion to the genera, the genera out of proportion to the families, and the families out of proportion to the orders. 2. Comparison of different families having unequal geographic ranges is usually inaccurate due to the great differences in the other factors controlling their speciation. Those families which do lend themselves to such a comparison show decidedly the effect of extent of distribution, e. g., the bats and some of the insectivores, the families of widest distribution having the largest indices of modification. A number of exceptions exist in the form of certain wide ranging genera which have a paucity of species. We have no adequate explanation for this phenomenon. 3. Comparison of the faunas of areas of different size gives very accurate results. A number of tabulations show as a whole an invariable increase in the index of modification as the distributional area is extended by the addition of either life zones, faunas, or associations. Such tabular comparisons were made for all the classes of terrestrial vertebrates, for several families of insects, and for the marine Amphipoda of the suborder Gammaridea. Allowing for explicable exceptions, the increase in number of lower systematic groups out of proportion to the increase of higher systematic groups as the area considered is enlarged is a remarkably constant and wide-spread phenomenon. 4. The theoretical explanation here proposed for this phenomenon involves a number of complex problems relating to evolution and speciation, including isolation, the time element, and causes of specific and generic modification. 5. Isolation is an important factor in speciation, since the separation of species into two or more parts allows the parts to become different. The degree of divergence of the segregated parts is largely dependent upon the duration of segregation. 6. Time, in conjunction with isolation and evolution, tends to increase the number of genera and species in a family, but the index of modification, i. e., the average number of species per genus, remains approximately the same in a given area. 7. Three types of modifications in animals may be named :-first, "extrinsic" modifications, which are induced by climate and other environmental conditions, and which lead to differentiation of species and subspecies primarily; second, "intrinsic" modifications, which are concomitant with a change in habits or mode of life of the animal, due to the occupation of a new ecologic niche, and which usually lead to generic or family differentiation; and third, neutral modifications, which are merely the result of the natural tendency of all animals to vary and to be subject to more or less orthogenetic evolution, modifications which can not be correlated with environmental conditions, nor with a change in mode of life of the animal, but which may be influenced largely by inherited tendencies. Such modifications are responsible for the production, through isolation, of different species to live under the same climatic and environmental conditions, and of different genera to occupy the same ecologic niche. 8. Specific modifications may be of three kinds: (1) extrinsic modifications, (2) neutral variations in segregated regions, (3) incipient generic modifications. Generic modifications may be (1) intrinsic modifications, or (2) neutral varations, given generic value by a longer period of segregation. 9. Since different types of a group of animals are usually found associated with different environmental conditions or different ecologic niches, and since it is common for animals, if unhindered, not only to extend their range continually into new territory, but also to occupy new ecologic niches, and since these tendencies lead to specific and generic differentiations, respectively, any given area will have a differentiation of species proportionate to its variety of environmental conditions, and of genera proportionate to its variety of suitable ecologic niches. 10. Since, as the area of distribution is extended, the chance of new conditions of climate and environment being represented remains approximately the same, the increase in number of species is nearly proportional to the increase in the area of distribution, but since the chance of new ecologic niches being represented in most cases constantly decreases, the increase in genera proceeds at an everdiminishing rate. This, going hand in hand with the nearly constant increase in species or subspecies, results in a constantly increasing index of modification.