•A generalized concept for the formation of nanostructured solids is presented resulting in materials with new atomic structures/new properties.•By varying the conditions for the formation of ...nano-crystals embedded in aqueous electrolytes, switchable quantum transistors were obtained.•The synthesis of a new kind of noncrystalline solid - called nanoglass - is proposed with atomic structures and properties that differ from the ones of today's glasses.•Influence of boundary conditions on self-assembly.•Development of a Single-Atom Transistor.
It is the aim of this review to discuss the preparation, the atomic structure and the properties of nanometer structured solids that consist either totally or partially of amorphous components. We shall try to present evidence suggesting that it is the variation of the boundary conditions applied for preparing these nano-structures that open the way to a variety of materials with new atomic arrangements/new properties ranging from nano-glasses to switchable atomic quantum transistors.
In order to discuss the basic ideas, we shall consider (in the first part of this review) solid materials that are assembled of nanometer-sized crystalline or amorphous building blocks connected by interfaces. The resulting materials are called nano-crystalline materials (nc) and nano-glasses (NG). Nano-crystalline materials and nano-glasses are solid materials composed of nanometer-sized crystalline or nanometer-sized glassy regions connected by crystal/crystal or glass/glass interfaces. As the atomic structures of these interfaces differ from the ones in the building blocks, the atomic and electronic structures of these interfaces differ from the ones in the building blocks. The atomic and the electronic structures (and hence the properties) of nano-crystalline materials and/or nano-glasses differ from the ones of single crystals or of glasses, respectively, that are available today with the same chemical compositions.
In the second part of this review solid materials will be discussed the properties of which are controlled by nanometer spaced solid/liquid or solid/gas interfaces. The first group of materials of this kind to be discussed are nano-porous metals with electrolyte or gas filled interconnected nanometer-sized ligaments. The properties of the resulting numerous solid/liquid or solid/gas interfaces may be controlled reversibly by external variables e.g. by applying an external voltage between an aqueous electrolyte in the pores and the nano-porous metal or by varying the chemical composition of the gas in the pores. Due to the high density (∼1015mm−3) of nano-scale ligaments, the entire nano-porous material reacts and becomes a solid of macroscopic dimensions with tunable mechanical, electric, magnetic, etc. properties. The other group of materials to be discussed in the second section of this review are nanometer-sized single crystals embedded in an aqueous electrolyte. By varying the boundary conditions for the formation of these nanometer-sized crystals, the size, the shape and the electronic structure of these nanometer-sized crystals can be switched reversibly so that switchable quantum transistors are obtained.
All of these findings may also be interpreted in a more general context suggesting that in all the above mentioned cases, complex structures evolve if the following four conditions are met: (i) a substrate or nucleation site, on which the structures can organize, (ii) a free volume providing the sterical degrees of freedom for building the new structures, (iii) a reservoir of building blocks (molecules, atoms, ions, crystallites, glassy clusters) from which the structures can be (reversibly or irreversibly) formed and finally (iv) confined geometries preventing the return to thermal equilibrium by preventing the growth of macroscopic single crystals. This general approach seems to open the way for understanding and developing the guidelines for the growth of new self-organized complex material systems far from thermal equilibrium.
Multiple factors over the lifetime of an individual, including diet, geography, and physiologic state, will influence the microbial communities within the primate gut. To determine the source of ...variation in the composition of the microbiota within and among species, we investigated the distal gut microbial communities harbored by great apes, as present in fecal samples recovered within their native ranges. We found that the branching order of host-species phylogenies based on the composition of these microbial communities is completely congruent with the known relationships of the hosts. Although the gut is initially and continuously seeded by bacteria that are acquired from external sources, we establish that over evolutionary timescales, the composition of the gut microbiota among great ape species is phylogenetically conserved and has diverged in a manner consistent with vertical inheritance.
The barrier to curing HIV-1 is thought to reside primarily in CD4+ T cells containing silent proviruses. To characterize these latently infected cells, we studied the integration profile of HIV-1 in ...viremic progressors, individuals receiving antiretroviral therapy, and viremic controllers. Clonally expanded T cells represented the majority of all integrations and increased during therapy. However, none of the 75 expanded T cell clones assayed contained intact virus. In contrast, the cells bearing single integration events decreased in frequency over time on therapy, and the surviving cells were enriched for HIV-1 integration in silent regions of the genome. Finally, there was a strong preference for integration into, or in close proximity to, Alu repeats, which were also enriched in local hotspots for integration. The data indicate that dividing clonally expanded T cells contain defective proviruses and that the replication-competent reservoir is primarily found in CD4+ T cells that remain relatively quiescent.
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•Integration sequencing identifies clonally expanded and single HIV-1 integrations in human subjects•Large clonal families of HIV-1+ cells are likely not part of the latent reservoir•HIV-1 integrates near or into a 30 bp INT-motif found in Alu repeats
HIV-1-infected CD4+ T cells that undergo clonal expansion are able to proliferate because their proviruses are defective. Conversely, the replication-competent reservoir is likely found in the subset of CD4+ T cells that carry unique integrations and remain quiescent.
Acquired immunodeficiency syndrome (AIDS) of humans is caused by two lentiviruses, human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2). Here, we describe the origins and evolution of these ...viruses, and the circumstances that led to the AIDS pandemic. Both HIVs are the result of multiple cross-species transmissions of simian immunodeficiency viruses (SIVs) naturally infecting African primates. Most of these transfers resulted in viruses that spread in humans to only a limited extent. However, one transmission event, involving SIVcpz from chimpanzees in southeastern Cameroon, gave rise to HIV-1 group M-the principal cause of the AIDS pandemic. We discuss how host restriction factors have shaped the emergence of new SIV zoonoses by imposing adaptive hurdles to cross-species transmission and/or secondary spread. We also show that AIDS has likely afflicted chimpanzees long before the emergence of HIV. Tracing the genetic changes that occurred as SIVs crossed from monkeys to apes and from apes to humans provides a new framework to examine the requirements of successful host switches and to gauge future zoonotic risk.
Ape Origins of Human Malaria Sharp, Paul M; Plenderleith, Lindsey J; Hahn, Beatrice H
Annual review of microbiology,
09/2020, Volume:
74, Issue:
1
Journal Article
Peer reviewed
Open access
African apes harbor at least twelve
Plasmodium
species, some of which have been a source of human infection. It is now well established that
Plasmodium falciparum
emerged following the transmission ...of a gorilla parasite, perhaps within the last 10,000 years, while
Plasmodium vivax
emerged earlier from a parasite lineage that infected humans and apes in Africa before the Duffy-negative mutation eliminated the parasite from humans there. Compared to their ape relatives, both human parasites have greatly reduced genetic diversity and an excess of nonsynonymous mutations, consistent with severe genetic bottlenecks followed by rapid population expansion. A putative new
Plasmodium
species widespread in chimpanzees, gorillas, and bonobos places the origin of
Plasmodium malariae
in Africa. Here, we review what is known about the origins and evolutionary history of all human-infective
Plasmodium
species, the time and circumstances of their emergence, and the diversity, host specificity, and zoonotic potential of their ape counterparts.
Most commercial copper nanoparticles are covered with an oxide shell and cannot be sintered into conducting lines/films by conventional thermal sintering. To address this issue, past efforts have ...utilized complex reduction schemes and sophisticated chambers to prevent oxidation, thereby rendering the process cost ineffective. To alleviate these problems, we demonstrate a reactive sintering process using intense pulsed light (IPL) in the present study. The IPL process successfully removed the oxide shells of copper nanoparticles, leaving a conductive, pure copper film in a short period of time (2 ms) under ambient conditions. The
in situ
copper oxide reduction mechanism was studied using several different experiments and analyses. We observed instant copper oxide reduction and sintering through poly(
N
-vinylpyrrolidone) functionalization of copper nanoparticles, followed by IPL irradiation. This phenomenon may be explained by oxide reduction either via an intermediate acid created by ultraviolet (UV) light irradiation or by hydroxyl (-OH) end groups, which act like long-chain alcohol reductants.
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•High pressure torsion (HPT) of bi-metallic laminate can induce vortex-like folding instabilities of metallic layers.•These multiscale vortices look similar to the ...Kelvin-Helmholtz-type flow instabilities in fluids.•Despite of this similarity, physical reasons for HPT-induced instabilities are principally different from those in fluids.•The vortices are driven by plastic instabilities due to local blocking of shear deformation.
We observed that high pressure torsion (HPT) of a bi-metallic laminate can induce vortex-like folding instabilities of layers. Thus, HPT leads to multiscale swirls which are perpendicular to the anvil axis. These instabilities are similar to folding of metallic surfaces during sliding and to co-axial swirls by HPT. The HPT induced vortex-like instabilities look very similar to the Kelvin-Helmholtz-type flow instabilities in fluids. We demonstrate in this work that this similarity is only apparent, and physical reasons for HPT-induced instabilituies are principally different from those in liquids. We show using finite element simulations that the folding and vortices of metallic layers are driven by plastic instabilities due to local blocking of shear deformation. Thus, HPT of layered samples leads to the multiscale movement of vortices in the material during deformation. These movements resemble turbulent flow of liquids and gases, but they have a completely different physical nature.
A new method named High Pressure Torsion Extrusion (HPTE) is proposed based on a modification of the conventional high pressure torsion technique of severe plastic deformation. During HPTE, a ...specimen is extruded through sectional containers rotating relative to each other. The specimen is subjected to shear deformation in the area where the containers meet each other. One of the main advantages of the HPTE process is that already after a single extrusion pass a high accumulated strain can be achieved in the specimen. Furthermore, the presence of a strong velocity gradient in the specimen cross-section during HPTE provides the possibility to process hybrid materials or composite parts with helical architecture of functional elements. The HPTE method is evaluated theoretically by using finite element methods (FEM) and experimentally by using HPTE for processing copper specimen and the results are presented and discussed.
Development of an effective AIDS vaccine is a global priority. However, the extreme diversity of HIV type 1 (HIV-1), which is a consequence of its propensity to mutate to escape immune responses, ...along with host factors that prevent the elicitation of protective immune responses, continue to hinder vaccine development. Breakthroughs in understanding of the biology of the transmitted virus, the structure and nature of its envelope trimer, vaccine-induced CD8 T cell control in primates, and host control of broadly neutralizing antibody elicitation have given rise to new vaccine strategies. Despite this promise, emerging data from preclinical trials reinforce the need for additional insight into virus—host biology in order to facilitate the development of a successful vaccine.
New breakthroughs have expanded our understanding of HIV, including the transmitted virus, envelope trimer structure, vaccine-induced T cells, and neutralizing antibodies. Haynes et al. examine how these advances have led to HIV vaccine strategies and discuss the need for additional insight into virus—host biology to facilitate successful vaccine development.
The gut microbial communities within great apes have been shown to reflect the phylogenetic history of their hosts, indicating codiversification between great apes and their gut microbiota over ...evolutionary timescales. But because the great apes examined to date represent geographically isolated populations whose diets derive from different sources, it is unclear whether this pattern of codiversification has resulted from a long history of coadaptation between microbes and hosts (heritable factors) or from the ecological and geographic separation among host species (environmental factors). To evaluate the relative influences of heritable and environmental factors on the evolution of the great ape gut microbiota, we assayed the gut communities of sympatric and allopatric populations of chimpanzees, bonobos, and gorillas residing throughout equatorial Africa. Comparisons of these populations revealed that the gut communities of different host species can always be distinguished from one another but that the gut communities of sympatric chimpanzees and gorillas have converged in terms of community composition, sharing on average 53% more bacterial phylotypes than the gut communities of allopatric hosts. Host environment, independent of host genetics and evolutionary history, shaped the distribution of bacterial phylotypes across the Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria, the four most common phyla of gut bacteria. Moreover, the specific patterns of phylotype sharing among hosts suggest that chimpanzees living in sympatry with gorillas have acquired bacteria from gorillas. These results indicate that geographic isolation between host species has promoted the evolutionary differentiation of great ape gut bacterial communities.
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