Natural Partners Research Articles

Realization of robust Ohmic contact for semiconducting black arsenic by coupling with graphene

Abstract Ohmic contacts are fundamental components in semiconductor technology, facilitating efficient electrical connection and excellent device performance. We employ the first principles calculations to show that semimetallic graphene is a natural Ohmic contact partner of monolayer semiconducting black arsenic (BAs), for which the valence band top is below the Fermi energy on the order of 102 meV. Thanks to the giant Stark effect induced from the van der Waals electron transfer from BAs to graphene, without destroying their respective band features. Remarkably, we show that this intrinsic Ohmic contact remains robust across a wide range of interlayer distance (adjustable by strain) or vertical electric field, whereas the weak spin splitting of 1 meV order induced by symmetry breaking plays little role in Ohmic contact. These findings reveal the potential applications of graphene-BAs in ultralow dissipation transistors.

Examining current regional intensity of trade in Africa: How strong are the trade linkages and implications for intra-Africa trade in the African Continental Free Trade Area

The African Continental Free Trade Area (AfCFTA) is a continent-wide free trade area which is expected to pave way for a continental customs union. This article assessed the current state and extent of intra-Africa trade in 2001-2018. The results give insights into the foundation which the current regional economic communities in Africa have put in place regarding intra- and inter-trade linkages. This is a foundation which the AfCFTA would utilise to achieve trade integration in a continent-wide economic integration arrangement that seeks to improve intra-Africa trade. Five regional groups were considered, namely Arab Maghreb Union, East African Community, the Economic Community of West African States, Economic Community of Central Africa States, and the Southern African Development Community. Intra-regional trade intensity index results show that trade within individual regional groups, and within Africa, is oriented towards respective member countries, although there is no evidence of increased inward orientation over time. Inter-regional trade intensity index results show that most regional groups trade intensively with each other, albeit at different levels. With increased market access in the AfCFTA through lower trade resistances between regional groups, inter-regional trade is expected to increase as per the volume of trade criteria in the natural trading partners hypothesis.

The promiscuous biotin ligase TurboID reveals the proxisome of the T3SS chaperone IpgC in Shigella flexneri.

Promiscuous biotin ligases derived from the bacterial enzyme BirA are used to identify proteins vicinal to a bait protein, thereby defining its proxisome. Despite the popularity of this approach, surprisingly little is known about its use in prokaryotes. Here, we compared the activity of four widely used promiscuous biotin ligases in the cytoplasm of Shigella flexneri, a pathogenic subgroup of Escherichia coli. Our data indicate that the kinetics of TurboID's biotinylating activity is the highest of those tested. In addition, TurboID showed reduced interaction with the natural BirA binding partners, BccP and the biotin operator, when compared to its ancestor BioID. We therefore evaluated the ability of TurboID to probe the proxisome of the type III secretion system (T3SS) chaperone IpgC and the transcriptional activator MxiE. When the T3SS is inactive (off-state), these proteins are inhibited by forming complexes with the T3SS substrates OspD1 and IpaBC, respectively. In contrast, when the T3SS is active (on-state), OspD1 and IpaBC are secreted allowing MxiE and IpgC to interact together and activate their target genes. The results obtained with the IpgC and TurboID fusions capture a good fraction of these known interactions. It also suggests that the availability of IpgC increases in the on-state, resulting in a greater number of proteins detected in its vicinity. Among these is the T3SS ATPase SpaL (also known as Spa47 or SctN), further supporting the notion that chaperones escort their substrate to the T3SS. Interestingly, a specific subset of proteins conserved in E. coli completes the IpgC proxisome in the on-state.IMPORTANCEPromiscuous biotin ligases are widely used to study protein function in eukaryotes. Strikingly, their use in prokaryotes has been rare. Indeed, the small volume and the cytoplasmic location of the biotin ligase's natural binding partners in these organisms pose unique challenges that can interfere with the study of the proxisome of proteins of interest. Here, we evaluated four of the most common promiscuous biotin ligases and found TurboID was best suited for use in the cytoplasm of Shigella flexneri. Using this method, we extended the proxisome of IpgC beyond its known direct binding partners involved in the regulation of the type III secretion system (T3SS) signaling cascade. Of particular interest for further study are transcription factors and housekeeping proteins that are enriched around IpgC when the T3SS is active. We propose a model in which the increased availability of IpgC in the on-state may allow cross-talk of the T3SS with other cellular processes.

Evidence for endogenous hydrogen peroxide production by E. coli fatty acyl-CoA dehydrogenase.

Aerobic organisms continuously generate internal superoxide and hydrogen peroxide, which can damage enzymes and impair growth. To avoid this problem cells maintain high levels of superoxide dismutases, catalases, and peroxidases. Surprisingly, we do not know the primary sources of these reactive oxygen species (ROS) in living cells. However, in vitro studies have shown that flavoenzymes can inadvertently transfer electrons to oxygen. Therefore, it seems plausible that substantial ROS may be generated when large metabolic fluxes flow through flavoproteins. Such a situation may arise during the catabolism of fatty acids. Acyl-CoA dehydrogenase (FadE) is a flavoprotein involved in each turn of the beta-oxidation cycle. In the present study the catabolism of dodecanoic acid specifically impaired the growth of strains that lack enzymes to scavenge hydrogen peroxide. The defect was absent from fadE mutants. Direct measurements confirmed that the beta-oxidation pathway amplified the rate of intracellular hydrogen peroxide formation. Scavenging-proficient cells did not display the FadE-dependent growth defect. Those cells also did not induce the peroxide stress response during dodecanoate catabolism, indicating that the basal defenses are sufficient to cope with moderately elevated peroxide formation. In vitro work still is needed to test whether the ROS evolve specifically from the FadE flavin site and to determine whether superoxide as well as peroxide is released. At present such experiments are challenging because the natural redox partner of FadE has not been identified. This study supports the hypothesis that the degree of internal ROS production can depend upon the type of active metabolism inside cells.

Expression of the Curvularia sp. P450 Monooxygenase Gene in Escherichia coli and Confirmation of Its 7-Hydroxylation Function

The diversity and uniqueness of fungal cytochromes P450 (CYP), capable of catalyzing the regio- and stereospecific hydroxylation of steroids, makes them important for microbiological synthesis of valuable hydroxysteroids. In the present work, the function of recombinant fungal P450 monooxygenase (CYPI) of Curvularia sp. strain VKM F-3040, a promising biocatalyst of 7-hydroxylation of androstane steroids, was studied. RT-PCR amplification of cDNA of the candidate CYPI gene and of the gene of its natural redox partner (POR), their cloning and heterologous expression in the cells of E. coli BL 21 DE(3) was carried out. In vitro experiments showed the ability of the obtained recombinant monooxygenase to catalyze hydroxylation of dehydroepiandrosterone at positions 7α and 7β. Our results expand the knowledge about fungal steroid hydroxylases and open up the prospects for the synthesis of valuable 7-hydroxysteroids by using recombinant producers.

Shifting to the online environment: exploring virtual and in-person collaborations between community college libraries and writing centers

Community college libraries and writing centers are natural partners due to their shared goals regarding academic support and student success, as well as their joint focus on the interrelated processes of writing and research. Research has shown that libraries at four-year institutions and writing centers collaborate in many ways, but little research has been conducted on collaborations at community colleges and whether these collaborations have moved to a virtual setting. Given the rise in online education at community colleges and students' need for developmental education in writing, this study used a qualitative survey approach to gain a better understanding of virtual and in-person collaborative efforts between writing centers and community college libraries. The survey was distributed via listservs and direct emails, with participation limited to those working at two-year institutions with writing centers. Survey findings demonstrated that library and writing center staff are implementing a variety of virtual and in-person collaborative efforts, such as student trainings, individual student appointments, the joint creation of online resources, and campus outreach. Practical implications for academic libraries and future directions for research are also discussed.

THE ARAB POLITICS OF IRAQ DURING THE BAATH PARTY RULE: BETWEEN THEORY AND PRACTICE

The paper analyzes one of the priority aspects of Iraq's foreign policy during the reign of the Ba’ath Party (1968-2003), relations with Arab countries. This policy was elevated to the rank of the most important state strategy and was given a special role in the scale of foreign policy priorities. It was allocated to an exceptional part of state politics, called “Arab politics”, “al-siyasa al-arabiyya”. The research examines the basic ideological and theoretical principles of Ba’athism, which formed the basis of “Arab politics” and on the basis of which the ruling Baath of Iraq built its relations with Arab countries. In this vein, it considers the fundamental principle of Ba'athism, the idea of "Arab unity", which constituted the first element of the party's slogan "Unity, freedom, socialism" and within the framework of which, at certain stages, Ba'ath sought to closely interact with Arab countries. Analyzing official documents, the author concludes that on the issue of Arab unity, Iraq could only unite with those countries that had political systems identical to it. Based on this logic, it becomes clear that among the Arab countries with which Iraq shared common ideological and political principles, Syria, as well as one of the centers of Arab nationalism, Egypt could be natural partners of Iraq within the framework of integration processes in the Arab world. In addition, these countries were among the countries that Iraq considered as opposing Israel and with which it primarily sought to establish close cooperation, including in the military sphere, to resolve the Palestinian problem. It was noted, however, that the radicalism of official Baghdad on this issue not only placed Iraq in isolation in the Arab world, but also sometimes created obstacles to inter-Arab integration and cooperation. Often in his policies there was a deep gap between the declared principles and their practical implementation. Within the framework of “Arab politics”, the article examines in detail Iraqi-Syrian and Iraqi-Egyptian bilateral relations throughout the entire period of the Baath Party’s rule in Iraq, revealing their most characteristic features and peculiarities.

De novo-designed transmembrane proteins bind and regulate a cytokine receptor

Transmembrane (TM) domains as simple as a single span can perform complex biological functions using entirely lipid-embedded chemical features. Computational design has the potential to generate custom tool molecules directly targeting membrane proteins at their functional TM regions. Thus far, designed TM domain-targeting agents have been limited to mimicking the binding modes and motifs of natural TM interaction partners. Here, we demonstrate the design of de novo TM proteins targeting the erythropoietin receptor (EpoR) TM domain in a custom binding topology competitive with receptor homodimerization. The TM proteins expressed in mammalian cells complex with EpoR and inhibit erythropoietin-induced cell proliferation. In vitro, the synthetic TM domain complex outcompetes EpoR homodimerization. Structural characterization reveals that the complex involves the intended amino acids and agrees with our designed molecular model of antiparallel TM helices at 1:1 stoichiometry. Thus, membrane protein TM regions can now be targeted in custom-designed topologies.

Being big in the big tent: Is fat social justice part of diversity, equity, and inclusion efforts on college campuses in the United States?

ABSTRACT Fat social justice and fat liberation movements share language, symbols, and strategies with many other movements striving to fight discrimination and stigma, such as movements centered on race, gender, sexuality, and disability. These communities should be natural partners with fat activists in striving for intersectional liberation and in fighting existing structures of privilege. It is less clear, however, the degree to which fat activism and activists are welcome in spaces explicitly constructed to address comprehensive approaches to social justice. To address this question, we examine a setting specifically built to address issues of privilege, oppression, and discrimination: diversity, equity, and inclusion organizations at US colleges and universities. We compile a data set of diversity, equity, and inclusion offices at 200 four-year colleges and universities in the US, with stratified samples to ensure inclusion across regions of the US, a broad variety of educational settings from large Research 1 institutions to small liberal arts colleges, and a subset of historically black colleges and universities. We examine whether and to what degree issues of fat social justice and liberation are included in university diversity and inclusion offices, websites, and materials. Findings show fat people, their experiences, and fat social justice issues are generally excluded in DEI spaces. We provide potential explanations for this exclusion and outline possible steps forward for those interested in fat social justice.

Do Trade Agreements Enhance Bilateral Trade? Focus on India and Sri Lanka

This article examines bilateral trade relations between the two important countries of South Asia, India and Sri Lanka, in light of the South Asian Free Trade Area (SAFTA) and the India–Sri Lanka Free Trade Agreement (ISFTA). The analysis period spans the years 1995 to 2020. The primary analysis found that bilateral trade has been sluggish and that the SAFTA and ISFTA agreements have had no discernible effect on these two countries’ bilateral trade performance. The causes of lackluster trade performance were investigated using the “revealed comparative advantage” and the “trade complementarity” indices. Clear evidence was found demonstrating that the reason for the bilateral trade’s consistent lackluster performance is due to both countries’ lack of revealed comparative advantage in the majority of product groups, followed by export similarity in the product groups where they do have a comparative advantage. The findings also confirm the suspicion of many observers that they are competitors rather than natural trading partners. Although any substantial future increase in their bilateral trade is improbable and fanciful, the paper reflects on methods of strengthening bilateral trade.

Relationship between labour and environmental law - Accidental or natural partners?

Relationship between labour and environmental law - Accidental or natural partners?

Identification of a Gene Encoding a New Fungal Steroid 7-Hydroxylase and Its Functional Characterization in Pichia pastoris Yeast.

The hydroxylation of steroids in the C7β position is one of the rare reactions that allow the production of value-added precursors in the synthesis of ursodeoxycholic acid and other pharmaceuticals. Recently, we discovered this activity in the ascomycete Curvularia sp. VKM F-3040. In this study, the novel gene of 7-hydroxylase (P450cur) was identified as being heterologously expressed and functionally characterized in Pichia pastoris. Transcriptome data mining and differential expression analysis revealed that 12 putative genes in Curvularia sp. mycelia significantly increased their expression in response to dehydroepiandrosterone (DHEA). The transcriptional level of the most up-regulated cytochrome P450cur gene was increased more than 300-fold. A two-gene construct with a candidate P450cur gene and the gene of its natural redox partner, NADPH-cytochrome P450 reductase (CPR), which is interconnected by a T2A element, was created. Using this construct, recombinant P. pastoris strains co-expressing fungal P450cur and CPR genes were obtained. The functional activity of the recombinant P450cur was studied in vivo during the bioconversion of androstane steroids. The fungal 7-monooxygenase predominantly catalyzed the 7β-hydroxylation of androstadienedione (ADD), DHEA, and androstenediol, whereas 1-dehydrotestosterone was hydroxylated by P450cur mainly at the C7-Hα position. To our knowledge, this is the first report of a recombinant yeast capable of catalyzing the 7α/β-hydroxylation of ADD and DHEA.

Unveiling the structural and functional consequences of the p.D109G pathogenic mutation in human αB-Crystallin responsible for restrictive cardiomyopathy and skeletal myopathy

αB-Crystallin (αB-Cry) is expressed in many tissues, and mutations in this protein are linked to various diseases, including cataracts, Alzheimer's disease, Parkinson's disease, and several types of myopathies and cardiomyopathies. The p.D109G mutation, which substitutes a conserved aspartate residue involved in the interchain salt bridges, with glycine leads to the development of both restrictive cardiomyopathy (RCM) and skeletal myopathy. In this study, we generated this mutation in the α-Cry domain (ACD) which is crucial for forming the active chaperone dimeric state, using site-directed mutagenesis. After inducing expression in the bacterial host, we purified the mutant and wild-type recombinant proteins using anion exchange chromatography. Various spectroscopic evaluations revealed significant changes in the secondary, tertiary, and quaternary structures of human αB-Cry caused by this mutation. Furthermore, this pathogenic mutation led to the formation of protein oligomers with larger sizes than those of the wild-type protein counterpart. The mutant protein also exhibited increased chaperone activity and decreased chemical, thermal, and proteolytic stability. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and fluorescence microscopy (FM) demonstrated that p.D109G mutant protein is more prone to forming amyloid aggregates. The misfolding associated with the p.D109G mutation may result in abnormal interactions of human αB-Cry with its natural partners (e.g., desmin), leading to the formation of protein aggregates. These aggregates can interfere with normal cellular processes and may contribute to muscle cell dysfunction and damage, resulting in the pathogenic involvement of the p.D109G mutant protein in restrictive cardiomyopathy and skeletal myopathy.

Medicine in the field: Growing connections between environmental and medical history

AbstractThis article argues that Environmental History and History of Medicine are disciplines that are natural allies and productive partners; successfully working across the sub‐disciplines will be essential to understanding current and future crises, including climate change and pandemics. While it is relatively easy to find acknowledged intersections between histories of science and/or technology and of the environment, so far these are less systematic and substantial in the history of medicine. Partly this is because there are points of serious methodological and theoretical tension, but I argue that these can function as moments of contact and provocation. Most obviously Environmental History poses challenges to historians of medicine in terms of the scale of our work in both its chronological and conceptual reach, and how we incorporate the non‐human, and even the non‐biotic as historical actors. History of Medicine offers approaches to help environmental historians negotiate their relationships with science, in particular the balance between science as a subject of study or as a source of data. Both disciplines share the struggle of combining focused, heavily contextualised local histories with the pressing need for globalised and ‘big picture’ historical explanations. In this review I will outline the main historiographical challenges to working across these subdisciplines—particularly in terms of scale and focus—and then consider the most productive intersections of these fields before making recommendations for future collaborative work.

Peacekeeping and crisis management: a brief assessment of EU-UN cooperation

The present short paper aims to add to the debate on the future of peacekeeping and crisis management in the current context of international relations. Starting from the premise that cooperation between the European Union and the United Nations (UN) for peace and security is a significant source of synergies between both organisations, the paper highlights the way in which the Common Foreign and Security Policy (CFSP) and the Common Security and Defence Policy (CSDP) were built, summarising the applicable legal regime, especially following the entry into force of the Lisbon Treaty. By providing a review of the legal background to EU crisis management and assessing the EU’s added value for UN-led efforts, the paper concludes that the Lisbon Treaty provisions provide the EU with the instruments necessary to assume a significant role in peacekeeping and crisis management. Although the EU’s natural partner in the field of peacekeeping and crisis management is the UN, there is growing uncertainty regarding the strength of the ties between both organisations as multilateralism traverses a crisis seemingly unlike others in the past.

Pieces of the puzzle? Coalition formation and tangential preferences

The similarity of parties’ policy preferences has long been considered an important determinant of whether they form a government coalition. That similarity has typically been assessed based on parties’ respective locations in a policy space. The degree to which parties care about different issues may, however, also vary. Parties that care about different issues may actually be the most compatible partners, as their tangential preferences would allow them to engage in policy logrolling and enable them to preserve their distinctiveness in the eyes of voters. This analysis tests arguments regarding the role of tangentiality and its interaction with policy proximity on the party composition of governments formed in Western Europe from 1945 to 2019. The findings show that parties that emphasise the same issues are more natural coalition partners provided the ideological differences between the parties are sufficiently similar.

Ochrona zwierząt i antysemityzm w niemieckim czasopiśmiennictwie specjalistycznym w latach 1919–1939

Animal Protection and Antisemitism in German Professional Press in the Years 1919–1939 The article discusses the entanglement of antisemitism and animal protection movement on the basis of the professional press of German veterinarians, animal protectionists, and meat producers from 1919 until 1939. The focal point is the question of shehitah. The article shows to what extent this question was a part of a general debate on the slaughter reform and the development of new stunning methods. Not surprisingly, most of the articles in the analyzed press were in favor of the introduction of the stunning obligation before the slaughter, which was from the Jewish perspective equal to the ban of shehitah. The article differentiates between the arguments of the majority of proponents of the obligation and those of their radical antisemitic colleagues. It argues that the animal protection movement in its majority cannot be described as racist or as a natural partner of national socialists, for only some representatives of it, such as Max Müller or Rudolf Einhauser from Munich, displayed a clear antisemitic rhetoric.

Histological changes in the uterine and ovarian walls in pyometra

In recent years, the number of small domestic animals, which have become cohabitants of people both in cities and in rural areas, has increased significantly. Keeping cats indoors with the use of artificial lighting has led to the fact that anestrus falls out of their sexual cycle, and the stages of arousal are manifested in them throughout the year. This phenomenon is the cause of various inflammatory processes in the uterus. The most common gynecological diseases in cats are pyometra, endometritis, and vaginitis. Violation of the hormonal status in the hypothalamus-pituitary chain in the absence of contact with natural partners is accompanied by a disorder of the function of the ovaries and uterus. A change in the hormonal balance, manifested by a violation of the ratio of estradiol and progesterone concentrations in the blood, affects the function of the endometrium and provokes an increase in the secretory activity of the uterine glands. Initiated in the arousal stage of the sexual cycle, it does not fade away but progresses even more. This is how the conditions for the emergence of an inflammatory process in the uterus are created and maintained. The course of the disease is accompanied by persistent morphological changes in the state of the uterus and all organs and their systems. Diagnosis of the disease is well-developed and does not present any difficulties in veterinary clinical practice. However, the approaches to substantiating the etiology and pathogenesis of the disease and the effectiveness and expediency of a conservative or operative treatment method are controversial. There are also limited reports on the histostructure of certain areas of the fallopian tubes and uterus, depending on the functional state of the cat’s body. The research aimed to investigate the histological structure of the uterus and ovaries of cats with pyometra. Ten explanted uteri and ovaries were subjected to histological examination in 10 cases of surgical treatment of cats with pyometra. In this research, it has been established that the pathohistological changes of the uterine wall due to pyometra are characterized by endometrial hypertrophy, the basis of which is hyperplasia with the formation of various forms of outgrowths covered with epithelium, followed by their dystrophy and the formation of detritus, which locally sticks to the endometrium and fills the uterine cavity, local desquamation of the serous mesothelium membrane, compaction of the muscular membrane, loosening of the vascular membrane, and dilatation of veins. The surface parts of the endometrial glands undergo dystrophic changes and cystic degeneration, manifested by hyperplasia of their walls and the formation of cavities filled with detritus of desquamated epithelium and cavities of “empty cysts” filled with remnants of detritus. Deep sections of the endometrial glands are reduced, but their histostructure is not transformed. Changes in the ovaries are manifested by focal desquamation of the mesothelium, the formation in the depth of the cortical substance of mainly one voluminous corpus luteum, atresia of follicles, and the presence of full-fledged tertiary follicles.

Monolayer Graphene-MoSSe van der Waals Heterostructure for Highly Responsive Gate-Tunable Near-Infrared-Sensitive Broadband Fast Photodetector.

Transition metal dichalcogenides (TMDCs) are potential two-dimentional materials as natural partners of graphene for highly responsive van der Waals (vdW) heterostructure photodetectors. However, the spectral detection range of the detectors is limited by the optical bandgap of the TMDC, which acts as a light-absorbing medium. Bandgap engineering by making alloy TMDC has evolved as a suitable approach for the development of wide-band photodetectors. Here, broadband (visible to near-infrared) photodetection with high sensitivity in the near-infrared region is demonstrated in a MoSSe/graphene heterostructure. In the ambient environment, the photodetector exhibits high responsivity of 0.6 × 102 A/W and detectivity of 7.9 × 1011 Jones at 800 nm excitation with a power density of 17 fW/μm2 and 10 mV source-drain bias. The photodetector shows appreciable responsivity in self-bias mode due to nonuniform distribution of MoSSe flakes on the graphene layer between the source and drain end and the asymmetry between the two electrodes. Time-dependent photocurrent measurements show fast rise/decay times of ∼38 ms/∼48 ms. A significant gate tunability on the efficiency of the detector has been demonstrated. The device is capable of low power detection and exhibits high operational frequency, gain, and bandwidth. Thus, the MoSSe/graphene heterostructure can be a promising candidate as a high-speed and highly sensitive near-infrared photodetector capable of operating at ambient conditions with low energy consumption.

Omne vivum ex ovo: the oocyte reprogramming and remodeling activities.

Understanding the establishment of post-fertilization totipotency has broad implications for modern biotechnologies. This review summarizes the current knowledge of putative egg components governing this process following natural fertilization and after somatic cell nuclear transfer. The mammalian oocyte is a unique cell, and comprehending its physiology and biology is essential for understanding fertilization, totipotency and early events of embryogenesis. Consequently, research in these areas influences the outcomes of various technologies, for example, the production and conservation of laboratory and large animals with rare and valuable genotypes, the rescue of the species near extinction, as well as success in human assisted reproduction. Nevertheless, even the most advanced and sophisticated reproductive technologies of today do not always guarantee a favorable outcome. Elucidating the interactions of oocyte components with its natural partner cell - the sperm or an 'unnatural' somatic nucleus, when the somatic cell nucleus transfer is used is essential for understanding how totipotency is established and thus defining the requirements for normal development. One of the crucial aspects is the stoichiometry of different reprogramming and remodeling factors present in the oocyte and their balance. Here, we discuss how these factors, in combination, may lead to the formation of a new organism. We focus on the laboratory mouse and its genetic models, as this species has been instrumental in shaping our understanding of early post-fertilization events.