Magneto-Thermoelastic Response in an Infinite Medium with a Spherical Hole in the Context of High Order Time-Derivatives and Triple-Phase-Lag Model

The article presents the interactions of magneto-thermoelastic effects in an isotropic material with a spherical cavity. The spherical cavity is expected to be tractionless and subjected to both heat and magnetic fields. The motion equation contains the Lorentz force. Laplace’s transformation methodology is used with a refined multi-time-derivative triple-phase-lag thermoelasticity theory to develop the generalized magneto-thermoelastic coupled solution. Many results were obtained to serve as benchmarks for future comparisons. The effects of time, magnetic field, and electric permittivity under the thermal environment were investigated.     

Refined Lord–Shulman Theory for 1D Response of Skin Tissue under Ramp-Type Heat

In this article, we present a mathematical model of thermoelastic skin tissue based on a refined Lord–Shulman heat conduction theory. A small thickness of skin tissue is considered to be one-dimensional with mechanical clamped surfaces. In addition, the skin tissue’s outer surface is subjected to ramp-type heating while its inner surface is adiabatic. A simple Lord–Shulman theory, as well as the classical coupled thermoelasticity, are also applied in this article. Laplace transform techniques and their inversions are calculated to return to the time domain. Numerical outcomes are represented graphically to discuss the significant impacts on the temperature, dilatation, displacement, and stress distributions. Such results provide a more comprehensive and better insight for understanding the behavior of skin tissue during the temperature distribution of a specific boundary condition.     

GPR174 signals via Gαs to control a CD86-containing gene expression program in B cells

GPR174 is abundantly expressed in B and T lymphocytes and has a role in restraining T cell responses, but the function of GPR174 in B cells is less clear. Here we report that upon in vitro culture B cells undergo a spontaneous GPR174-dependent activation process that is associated with marked changes in gene expression, including up-regulation of Cd86, Nr4a1, Ccr7, and phosphodiesterases. B cells lacking Gαs show a block in induction of the GPR174-dependent program. Spontaneous up-regulation of CD86 in cultured B cells is dependent on protein kinase A. Both GPR174- and Gαs-deficient B cells show enhanced survival in culture. In vivo, GPR174 contributes to NUR77 expression in follicular B cells and is needed for establishing a marginal zone compartment of normal size. Treatment of mice with lysophosphatidylserine (lysoPS), a GPR174 ligand, is sufficient to promote CD86 up-regulation by follicular B cells. These findings demonstrate that GPR174 can signal via Gαs to modulate B cell gene expression and show this can occur in vivo in response to lysoPS. Additionally, the findings illuminate a pathway that might be targeted to improve systems for the in vitro study of B cell responses.

G-protein–coupled receptors (GPCRs) comprise a large family of seven-transmembrane signaling proteins, many of which have roles in the development and function of the mammalian immune system. The outcome of GPCR signaling is determined via coupling to various G proteins. Signaling via Gαi-coupled GPCRs promotes cell migration, whereas GPCR coupling to Gα12/13 proteins often leads to migration inhibition. In contrast, Gαs signaling exerts its effect through cAMP production and leads to complex and often suppressive effects on immune cell activation and proliferation. GPCR GPR174 is one of several related X-linked receptors that are highly expressed on lymphocytes (1–3). Several genome-wide association studies (GWAS) have linked GPR174-associated single-nucleotide polymorphisms (SNPs) to autoimmune disorders including Graves’ and Addison’s diseases (4–6).GPR174 was found to be a receptor for lysophosphatidylserine (lysoPS) and was suggested to signal via Gα12/13-containing heterotrimeric G proteins (1). Studies on GPR174-deficient mice revealed a role for the receptor in restraining T regulatory (Treg) cell development and function (2) and conventional T cell proliferation and IL-2 production (7, 8). In these reports, signaling was suggested to occur via Gαs-containing heterotrimeric G proteins (7, 8). In another study, GPR174 was reported to support B cell migration to spleen stromal cell culture supernatants and biochemical fractionation led to the suggestion that CCL19 and CCL21, well-defined CCR7 ligands, were ligands for GPR174 (3). In that study, GPR174 was suggested to signal via Gαi and Gα13 (3). Taken together, there is currently a lack of clear understanding regarding the signaling pathway(s) engaged downstream of GPR174.CD86 is a critical costimulatory molecule in antigen-presenting cells including B cells (9, 10). Induction of CD86 by B cell receptor (BCR) signaling is an important feature of the BCR-induced activation program, although CD86 can also be induced in B cells by CD40 and cytokine signaling (11–13). Interestingly, Cd86 was originally characterized as a cAMP-inducible gene in B cells (14–18). However, since the BCR, CD40, and cytokines are not thought to induce CD86 via cAMP, the receptors leading to cAMP-mediated induction of CD86 in B cells have been unclear.The study of B cells in vitro has been critical to numerous advances in the understanding of adaptive immunity and it remains a crucial method for dissecting the B cell response. Although not widely reported on, it is generally understood by B cell biologists that B cells undergo some amount of gene expression change during in vitro culture. Indeed, this aspect of cultured B cells presented a major challenge to efforts by the Alliance for Cell Signaling (19, 20) to dissect the signaling circuits in mouse B cells. The pathways involved in causing these gene expression changes are not understood.Here we report that cultured follicular B cells rapidly up-regulate CD86 independently of stimulation in a GPR174- and Gαs-dependent manner. The GPR174-mediated response was not dependent on exogenous ligand or BCR signaling. RNA-sequencing analysis revealed that B cells underwent changes in expression of 1,000 genes after 4 h of unstimulated culture and many of these changes were GPR174 dependent. This included induction of Cd86, Nr4a1, Ccr7, and phosphodiesterases and down-regulation of immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing receptors. There was a strong overlap in the alterations in gene expression between GPR174- and Gαs-deficient B cells, indicating that GPR174 signals via Gαs in follicular B cells. When B cells were maintained in vitro for 1 to 2 d in the absence of stimulation, GPR174 and Gαs deficiencies were associated with augmented survival. In vivo GPR174 deficiency led to reduced NUR77-GFP reporter expression, and GPR174- and Gαs-deficient mice had a reduced marginal zone (MZ) B cell compartment. Treatment of mice with lysoPS was sufficient to cause increased CD86 expression by follicular B cells. These findings establish GPR174 as a receptor capable of exerting a large influence on B cell gene expression and they provide insight into the B cell properties that can be influenced by the receptor.     

Effect of Mg Addition on the Microstructure and Properties of a Heat-Affected Zone in Submerged Arc Welding of an Al-Killed Low Carbon Steel

To reveal the effect of Mg treatment on the microstructure evolution behavior in the actual steel welding process, the microstructure and properties of Al-deoxidized high-strength ship plate steel with Mg addition were analyzed after double-side submerged arc welding. It was found that the Al–Mg–O + MnS inclusion formed under 26 ppm Mg treatment could promote acicular ferrite (AF) nucleation in the coarse-grained heat-affected zone (CGHAZ) and inhibit the formation of widmanstätten ferrite and coarse grain boundary ferrite. In the fine-grained heat-affected zone (FGHAZ) and intercritical heat-affected zone (ICHAZ), polygonal ferrite and pearlite were dominant. Al–Mg–O+MnS cannot play a role in inducing AF, but the grain size of ferrite was refined by Mg addition. The impact toughness in HAZ of the Mg-added steel was higher than that of Mg-free steel. With the heat-input rising from 29.55 to 44.11 kJ/cm, it remained relatively stable in Mg-treated steel. From the fusion line to the base metal, the micro-hardness of the fusion zone, CGHAZ, ICHAZ and FGHAZ decreased to some extent after Mg addition, which means the cold cracking tendency in the welding weak zone could be reduced. Finally, the mechanisms of Mg-containing inclusion-induced AF were also systematically discussed.     

From the Cover: A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene

Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria’s host is a “farmer” clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer’s spore production and depresses a nonfarmer’s spore production. Genome sequence and phylogenetic analyses identify a derived point mutation in the food strain that generates a premature stop codon in a global activator (gacA), encoding the response regulator of a two-component regulatory system. Generation of a knockout mutant of this regulatory gene in the nonfood bacterial strain altered its secondary metabolite profile to match that of the food strain, and also, independently, converted it into a food source. These results suggest that a single mutation in an inedible ancestral strain that served a protective role converted it to a “domesticated” food source.     

Simulation Research on Impact Contact Behavior between Coal Gangue Particle and the Hydraulic Support: Contact Response Differences Induced by the Difference in Impacted Location and Impact Material

In the process of top coal caving, coal gangue particles may impact on various parts of the hydraulic support. However, at present, the contact mechanism between coal gangue and hydraulic support is not entirely clear. Therefore, this paper first constructed the accurate mathematical model of the hydraulic cylinder equivalent spring stiffness forming by the equivalent series of different parts of emulsion and hydraulic cylinder, and then built the mesh model of the coal gangue particles and the support’s force transmission components; on this basis, the rigid–flexible coupling impact contact dynamic model between coal gangue and hydraulic support was established. After deducing contact parameters and setting impact mode, contact simulations were carried out for coal particles impacting at the different parts of the support and coal/gangue particles impacting at the same component of the support, and the contact response difference in the support induced by the difference in impacted component and coal/gangue properties was compared and studied. The results show that the number of collisions, contact force, velocity and acceleration of impacted part are different when the same single coal particle impact different parts of the support. Various contact responses during gangue impact are more than 40% larger than that of coal, and the difference ratio can even reach 190%.     

Animals in a bacterial world,a new imperative for the life sciences

In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal–bacterial interactions, whether in shared ecosystems or intimate symbioses, is fundamentally altering our understanding of animal biology. Specifically, we highlight recent technological and intellectual advances that have changed our thinking about five questions: how have bacteria facilitated the origin and evolution of animals; how do animals and bacteria affect each other’s genomes; how does normal animal development depend on bacterial partners; how is homeostasis maintained between animals and their symbionts; and how can ecological approaches deepen our understanding of the multiple levels of animal–bacterial interaction. As answers to these fundamental questions emerge, all biologists will be challenged to broaden their appreciation of these interactions and to include investigations of the relationships between and among bacteria and their animal partners as we seek a better understanding of the natural world.     

Achieving High-Strength and Toughness in a Mg-Gd-Y Alloy Using Multidirectional Impact Forging

High strength and toughness are achieved in the Mg-4.96Gd-2.44Y-0.43Zr alloy by multidirectional impact forging (MDIF). The forged sample has a fine-grained microstructure with an average grain size of ~5.7 µm and a weak non-basal texture, and it was characterized by an optical microscope (OM), scanning electron microscope (SEM), and electron back-scattering diffraction (EBSD). Tensile results exhibit the tensile yield strength (TYS) and static toughness (ST) of as-homogenized alloy dramatically increased after forging and aging, i.e., the TYS increased from 135−5+4 MPa to 337−2+2 MPa, and the ST enhanced from 22.0−0.5+0.3 MJ/m³ to 50.4−5.4+5.3 MJ/m³. Specifically, the forged Mg-Gd-Y-Zr alloy owns higher TYS than that of commercial rolled WE54 (Mg-5.25Y-3.5Nd-0.5Zr) and WE43 (Mg-4.0Y-3.0Nd-0.5Zr) alloys.     

The synthesis of the Gγ and Aγ chains of human fetal hemoglobin in erythroid colonies cultured from peripheral blood BFUe's of normal adults and newborn and of subjects with an Aγ or a Gγ chain abnormal fetal hemoglobin

Peripheral blood mononuclear cells from normal adults, normal newborn infants, and from newborn and adult subjects with one of three γ chain variants (^GγF-Malta I, ^GγF-Port Royal, ^AγF-Hull) were cultured in vitro with erythropoietin. The ³⁵S-methionine-labelled hemoglobin from 13- to 15-day-old BFUe-derived colonies was studied by chromatography on columns of DEAE-cellulose and the quantities of Hbs A₂, F_x, and F₀ determined. The percentages of ^Gγ and ^Aγ chains in isolated Hb F_x and Hb F₀ were determined using high-performance liquid chromatography (HPLC) of the tryptic peptides of these proteins. Calculation of these percentages was based on the total activities of the ^GγT-15 and ^AγT-15 peptides which contain one (³⁵S-labelled) methionyl residue each and can be separated by the HPLC procedure. The data show an increased synthesis of Hb F in the ?adult”? colonies and a decreased synthesis in the ?newborn”? colonies. The ^Gγ to ^Aγ ratio of the Hb F from adult colonies varied greatly. The percentages of ^Gγ and ^Aγ chains in the Hb F from adult colonies correlated with the percentages in the Hb F isolated from the Hb F of circulating red blood cells. The ^Gγ to ^Aγ ratio in the Hb F from newborn colonies was high as in the Hb F from cord blood samples. ^Gγ and ^Aγ chain abnormal Hb F variants were readily detectable in colonies from both adults and newborn. The ^Gγ to ^Aγ ratio in the Hb F of colonies of adult Hb F-Malta I and Hb F-Hull heterozygotes approached 1, but that of adult Hb F-Port Royal heterozygotes remained about as high as in colonies from newborn heterozygotes. The percent Hb F-Port Royal in the Hb F of adult colonies was twice that in the Hb F of newborn colonies. These results are discussed in the light of information from recent detailed studies of genomic DNA assuming controlling functions for the segments of DNA that are interspersed between the various structural genes.