Search

Service combinatorial optimisation is one of the key issues of green resource supply in a cloud environment. During the execution process of service composition, service composition fails due to compatibility, resource competition, failure, and other reasons between sub-services. To solve the above problems, this paper focuses on the service combinatorial optimisation problem in green cloud computing resource supply. It proposes a service combinatorial optimisation model based on layered coloured Petri nets (LCPN). The service composition process meets the functional attributes of user needs and focuses on non-functional attributes such as service quality and execution time. It can dynamically adjust the service composition scheme to ensure feasibility and business logic compatibility. The experimental results show that the service combination scheme considering atomic service quality and virtual machine processing capability has the highest average comprehensive index value, 12.09% higher than the scheme considering only one factor. In handling concurrent events, the LCPN network can allocate resources reasonably, ensuring the compatibility of message interaction between various modules and the business logic of various transactions.

Aquaporins are transmembrane channels that allow for the passive permeation of water and other small molecules across biological membranes. Their channel activities are sensitive to mercury ions. Intriguingly, while most aquaporins are inhibited by mercury ions, several aquaporins are activated by mercury ions. The molecular basis of the opposing aquaporin regulation by mercury remains poorly understood. Herein, we investigated AqpZ inhibition and AQP6 activation upon binding of mercury ions using solid-state NMR (ssNMR) and molecular dynamics (MD) simulations. Based on the structure of the Hg–AqpZ complex constructed by MD simulations and ssNMR, we identified that the pore closure was caused by mercury-induced conformational changes of the key residue R189 in the selectivity filter region, while pore opening was caused by conformational changes of residues H181 and R196 in the selectivity filter region in AQP6. Both conformational changes were caused by the disruption of the H-bond network of R189/R196 by mercury. The molecular details provided a structural basis for mercury-mediated functional changes in aquaporins.

After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death1,2. Yet with targeted interventions, these processes can be mitigated or reversed, even minutes or hours post mortem, as also reported in the isolated porcine brain using BrainEx technology3. To date, translating single-organ interventions to intact, whole-body applications remains hampered by circulatory and multisystem physiological challenges. Here we describe OrganEx, an adaptation of the BrainEx extracorporeal pulsatile-perfusion system and cytoprotective perfusate for porcine whole-body settings. After 1 h of warm ischaemia, OrganEx application preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs. Commensurately, single-nucleus transcriptomic analysis revealed organ- and cell-type-specific gene expression patterns that are reflective of specific molecular and cellular repair processes. Our analysis comprises a comprehensive resource of cell-type-specific changes during defined ischaemic intervals and perfusion interventions spanning multiple organs, and it reveals an underappreciated potential for cellular recovery after prolonged whole-body warm ischaemia in a large mammal.

In many species of Gram-positive bacteria, SepF participated in the membrane tethering of FtsZ Z-ring during bacteria division. However, atomic-level details of interaction between SepF and FtsZ in an assembled state are lacking. Here, by combining solid-state NMR (SSNMR) with biochemical analyses, the interaction of Bacillus subtilisSepF and the C-terminal domain (CTD) of FtsZ was investigated. We obtained near complete chemical shift assignments of SepF and determined the structural model of the SepF monomer. Interaction with FtsZ-CTD caused further packing of SepF rings, and SSNMR experiments revealed the affected residues locating at α1, α2, β3, and β4 of SepF. Solution NMR experiments of dimeric SepF constructed by point mutation strategy proved a prerequisite role of α–α interface formation in SepF for FtsZ binding. Overall, our results provide structural insights into the mechanisms of SepF–FtsZ interaction for better understanding the function of SepF in bacteria.

Hydrocephalus, characterized by cerebral ventricular dilatation, is routinely attributed to primary defects in cerebrospinal fluid (CSF) homeostasis. This fosters CSF shunting as the leading reason for brain surgery in children despite considerable disease heterogeneity. In this study, by integrating human brain transcriptomics with whole-exome sequencing of 483 patients with congenital hydrocephalus (CH), we found convergence of CH risk genes in embryonic neuroepithelial stem cells. Of all CH risk genes, TRIM71/lin-41harbors the most de novo mutations and is most specifically expressed in neuroepithelial cells. Mice harboring neuroepithelial cell-specific Trim71deletion or CH-specific Trim71mutation exhibit prenatal hydrocephalus. CH mutations disrupt TRIM71 binding to its RNA targets, causing premature neuroepithelial cell differentiation and reduced neurogenesis. Cortical hypoplasia leads to a hypercompliant cortex and secondary ventricular enlargement without primary defects in CSF circulation. These data highlight the importance of precisely regulated neuroepithelial cell fate for normal brain–CSF biomechanics and support a clinically relevant neuroprogenitor-based paradigm of CH.

In general, a spin-polarized light beam cannot couple its spin angular momentum (SAM) with intrinsic orbital angular momentum (IOAM) without spin reversal. Here we find that nonlinear media can give the spin-polarized photon an IOAM, as they travel in the media due to the nonlinear susceptibility along the transmission direction, which does not require spin reversal. To characterize this SAM-to-IOAM conversion process, we establish an evolution ray equation for photons carrying IOAM by reference to the Schrödinger equation. We further reveal the inherent physics of such a phenomenon from a full-wave perspective and find that the vortex generation originates from the nonlinear-induced geometric phase.

The bacterial mechanosensitive channel of large conductance (MscL) functions as a pressure-relief safety valve to prevent cells from lysing during sudden hypo-osmotic shock. The hydrophobic gate of MscL in the closed state forms a barrier to the permeation of ions and water molecules and can be switched to the open state for releasing solutions and ions. Currently, the gate-constituting residues and the functional role of these residues in the hydrophobic gate of MscL remain elusive and controversial. Here, we employ magic angle spinning solid-state nuclear magnetic resonance (ssNMR) techniques and functional assays to investigate the hydrophobic gate of MscL from Methanosarcina acetivorans(Ma-MscL) in lipid bilayers. We obtain chemical shift assignments of ∼70% residues of Ma-MscL and predict its 3D structure. Based on the structural characterization, we identify that the residues I21–T30 in the transmembrane helix 1 constitute the hydrophobic gate by detecting water distributions in the transmembrane pore using ssNMR H/D exchange and water-edited experiments. By using ssNMR structural characterization and functional assays, we reveal that the packing of aromatic rings of F23 in each subunit of Ma-MscL is critical to the hydrophobic gate, and hydrophilic substitutions of the other functionally important residues A22 and G26 modulate channel gating by attenuating hydrophobicity of constriction of F23.

Negative refraction is an exotic optical phenomenon that is usually observed at the interface between a positive-index material and a negative-index, or “left-handed” material. One direct application of negative refraction is the Veselago lens, a flat lens that can focus the light emitted by a point source located on one side of the negative index medium onto the opposite side. Besides negative-index materials, Veselago lensing effect has been observed with two-dimensional crystals possessing Dirac points, such as graphene for electrons. Here we observe all-angle negative refraction and Veselago imaging in three dimensions with a Type I Weyl metamaterial. Furthermore, our ideal Weyl metamaterial exhibits remarkable spin-selective transmission around the Weyl frequency that arises from its intrinsic chiral optical response. Our results show that the ideal Weyl metacrystal provides a versatile platform for lensing applications and novel photon-spin selective devices.

The single-file water transport through a biomimic water channel consisting of a (6,6) carbon nanotube (CNT) with different types of external point charges is studied using molecular dynamics simulations. It is demonstrated that, as in the aquaporins, asymmetrically positioned charges cannot generate robust unidirectional water flow in the CNT. Thermal fluctuation in bulk water competes with charge affinity to steer the water transport, resulting in nonmonotonic flow with intermittent reversal of transport direction. The energetic analysis suggests that the water−water interaction, determined by dipole orientation configuration, influences the transport rate significantly. These findings can provide correct biomimic understanding of water transport properties and will benefit the design of efficient functional nanofluidic devices.

•The voltage of lithium-ion batteries under high impact is measured, with a sharp drop and slow rise.•The partial short circuit of the separator and the relaxation effect contribute to the impact failure.•MI-PNGV model is proposed to simulate the failures under different extreme mechanical conditions.•The design guideline is proposed to avoid the mechanic impact failure of lithium-ion batteries.

An optical limiter was designed and fabricated. The device consists of an organic solution sandwiched between a polymer slab and a transparent relief polymer grating with a triangular groove. At low power the device has a high transmittance because the refractive index of the solution is matched with those of the slab and the grating materials and because the grating does not diffract. However, high power makes the organic solution thermally vaporize and makes the indices of the solution, slab, and grating materials become mismatched, which causes the grating to appear. The incident light is strongly absorbed, scattered, and self-defocused by the organic solution, and the grating suppresses the zero-order diffraction. Thus the transmitted light energy becomes lower than the damage threshold of human eyes or optical sensors. The device is an effective protection for human eyes or optical sensors against broadband pulsed-laser damage.

Better understanding of the progression of neural stem cells (NSCs) in the developing cerebral cortex is important for modeling neurogenesis and defining the pathogenesis of neuropsychiatric disorders. Here, we use RNA sequencing, cell imaging, and lineage tracing of mouse and human in vitroNSCs and monkey brain sections to model the generation of cortical neuronal fates. We show that conserved signaling mechanisms regulate the acute transition from proliferative NSCs to committed glutamatergic excitatory neurons. As human telencephalic NSCs develop from pluripotency in vitro, they transition through organizer states that spatially pattern the cortex before generating glutamatergic precursor fates. NSCs derived from multiple human pluripotent lines vary in these early patterning states, leading differentially to dorsal or ventral telencephalic fates. This work furthers systematic analyses of the earliest patterning events that generate the major neuronal trajectories of the human telencephalon.

Integral impeller is a key component of turbocharger. Although the research on structural design and machining of integral impeller has made some progress, The technical route of design and processing of integral impeller for vehicle turbocharger is cumbersome and slightly less efficient. A novel technology route of structure design and CNC machining for the integral impeller is proposed in this paper. Firstly, according to the relevant design criteria, the relevant parameters such as the overall impeller height, the blade height, the impeller inlet diameter, the impeller outlet diameter and the number of blades are obtained. Then the 3D model is created in the CAXA manufacturing engineer. Using CAXA CAM, the tool paths are generated in order to output CNC machining programs. The CNC machining programs are imported into the five-axis machining center for machining the integral impeller. The technology route can effectively improve the design efficiency, reduce the cost of design and manufacturing, and shorten the design cycle to a certain extent.

For compact explosively driven ferromagnetic impulse source used in magnetic flux compression generators, the relations between the magnet's demagnetization rate and the shock wave pressure are theoretically analyzed. A nonlinear finite element method is adopted to conduct numerical simulation on the magnet's impact loading process. The propagation rules and pressure distributions of shock wave within hollow cylindrical NdFeB magnet caused by lateral impact of single-ended and double-ended initiating explosives are explored. The numerical simulation results show that, the pressures at both ends resulting from lateral impact of double-ended initiating explosives on hollow cylindrical magnet are low; double-ended initiating has faster demagnetization rate, swifter variation of flux and higher electromotive force of inductive output than single-ended initiating.

In order to realize the simulation test of key components under continuous high impact environment, a continuous high impact test equipment based on direct impact loading of multiple impact heads is designed. In view of the collision contact problem between the impact head of semi-cylindrical structure and the tested object, a mathematical model of collision contact force is established based on Hertz line contact theory and hysteretic damping model, the change of the contact force and the energy loss are described in the form of nonlinear elastic force and equivalent damping, provide theoretical support for impact parameter analysis of the test equipment. On the basis of theoretical analysis, the overload acceleration of continuous high impact test equipment is verified combined with dynamic simulation and experiment, demonstrate the rationality and feasibility of the test equipment design.

ABSTRACTFifty clinical Mycoplasma pneumoniaestrains were isolated from 370 children with respiratory tract infections. Four strains were susceptible to macrolides, while the other 46 (92%) were macrolide resistant. The molecular mechanism of resistance was shown to be associated with point mutations in 23S rRNA at positions 2063 and 2064.

This paper considers the simultaneous attack of a stationary target by multiple missiles. A novel fixed-time distributed guidance law based on the proportional navigation (PN) guidance law is designed by integrating a consistent control technique into the guidance strategy. This guarantees that the time-to-go of the missile becomes consistent. The guidance law adopts a discrete design, and a compensation item driven by normal acceleration is added to tangential acceleration. This eliminates the potential singularity problem when the heading angle is zero before the consistency is obtained, and thus the multiple missile system still converges in fixed time. In addition, the proposed guidance law can be applied to both undirected and directed graphs. Furthermore, two improved guidance laws are proposed to improve the robustness of the system against adverse effects caused by input delays and topology switching failures and to provide a theoretical proof. Finally, a simulation is used to verify the performance of the distributed guidance law and its robustness against the above failures. [ABSTRACT FROM AUTHOR]