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To study the lubrication performance of tilting-pad thrust bearing (TPTBs) during start-up in nuclear pump, a hydrodynamic lubrication model of TPTBs was established based on the computational fluid dynamics (CFD) method and the fluid-structure interaction (FSI) technique. Further, a mesh motion algorithm for the transient calculation of thrust bearings was developed based on the user defined function (UDF).

Optomechanical systems have been exploited in ultrasensitive measurements of force, acceleration and magnetic fields. The fundamental limits for optomechanical sensing have been extensively studied and now well understood—the intrinsic uncertainties of the bosonic optical and mechanical modes, together with backaction noise arising from interactions between the two, dictate the standard quantum limit. Advanced techniques based on non-classical probes, in situ ponderomotive squeezed light and backaction-evading measurements have been developed to overcome the standard quantum limit for individual optomechanical sensors. An alternative, conceptually simpler approach to enhance optomechanical sensing rests on joint measurements taken by multiple sensors. In this configuration, a pathway to overcome the fundamental limits in joint measurements has not been explored. Here we demonstrate that joint force measurements taken with entangled probes on multiple optomechanical sensors can improve the bandwidth in the thermal-noise-dominant regime or the sensitivity in the shot-noise-dominant regime. Moreover, we quantify the overall performance of entangled probes with the sensitivity–bandwidth product and observe a 25% increase compared with that of classical probes. The demonstrated entanglement-enhanced optomechanical sensors would enable new capabilities for inertial navigation, acoustic imaging and searches for new physics.

The raphe nucleus is critical for feeding, rewarding and memory. However, how the heterogenous raphe neurons are molecularly and structurally organized to engage their divergent functions remains unknown. Here, we genetically target a subset of neurons expressing VGLUT3. VGLUT3 neurons control the efficacy of spatial memory retrieval by synapsing directly with parvalbumin-expressing GABA interneurons (PGIs) in the dentate gyrus. In a mouse model of Alzheimer’s disease (AD mice), VGLUT3→PGIs synaptic transmission is impaired by ETV4 inhibition of VGLUT3 transcription. ETV4 binds to a promoter region of VGLUT3 and activates VGLUT3 transcription in VGLUT3 neurons. Strengthening VGLUT3→PGIs synaptic transmission by ETV4 activation of VGLUT3 transcription upscales the efficacy of spatial memory retrieval in AD mice. This study reports a novel circuit and molecular mechanism underlying the efficacy of spatial memory retrieval via ETV4 inhibition of VGLUT3 transcription and hence provides a promising target for therapeutic intervention of the disease progression.

Green and biodegradable materials with great mechanical properties and biocompatibility will offer new opportunities for next-generation high-performance biological materials. Herein, the novel oriented shish kebab crystals of a novel poly(trimethylene carbonate-lactide-glycolide) (PTLG) vascular stent are first reported to be successfully fabricated through a feasible solid-state drawing process to simultaneously enhance the mechanical performance and biocompatibility. The crystal structure of this self-reinforced vascular stent was transformed from spherulites to a shish kebab crystal, which indicates the mechanical interlocking effect and prevents the lamellae from slipping with a significant improvement of mechanical strength to 333 MPa. Meanwhile, it is different from typical biomedical polymers with smooth surface structures, and the as-obtained PTLG vascular stent exhibits a bionic surface morphology with a parallel micro groove and ridge structure. These ridges and grooves were attributed to the reorganization of cytoskeleton fiber bundles following the direction of blood flow shear stress. The structure and parameters of these morphologies were highly similar to the inner surface of blood vessels of the human, which facilitates cell adhesion growth to improve its proliferation, differentiation, and activity on the surface of PTLG.

In principle, quantum entanglement gives advantages in radar detection even under noisy and lossy operating conditions. More than a decade after the proposal, the predicted quantum advantage has finally been demonstrated at microwave frequencies.

In this paper, we presented a novel low-cost method for diamond-wire-sawn (DWS) multicrystalline silicon (mc-Si) wafer texturation based on the metal-assisted chemical etching process with Ag/Cu dual elements and nanostructure rebuilding (NSR) treatment to remove the saw marks and to realize uniform invert pyramid textured structures. Benefiting from both the increased optical absorption and better passivation, an efficiency of 18.71% for invert pyramid mc-Si solar cells from a DWS wafer with a standard size of 156 × 156 mm2 was obtained, which was 0.58% and 2.33% absolutely higher than that (18.13%) of the traditional mc-Si solar cell and than that (16.38%) of the black mc-Si solar cell without NSR treatment, respectively.

The pumped storage power plant, which has the energy conversion and storage capacity, is an important solution for improving the power grid absorption ability to the unstable and fluctuating new energy from wind farms, as well as photovoltaic power stations. The modular multilevel converter (MMC) is a competitive topology for driving the pumped storage motor due to the advantages of high output power level and low output current harmonics. However, the voltages of the sub-module capacitors fluctuate largely when the MMC is operating at low-frequency stage, which would lead to an abnormal start-up process or an unstable low-speed running state of the variable speed pumped storage system. In order to suppress the low-frequency voltage fluctuation of the MMC sub-module capacitors, this paper proposes a charge channel topology including in-phase and inter-phase channel between the sub-modules for transferring the capacitor charge. Then, the reverse fluctuating fundamental component and third harmonic circulating component, as well as the synchronizing fluctuating second harmonic component, of the sub-module capacitor voltages could be counteracted, respectively. Eventually, the start-up operation performance, as well as the low-speed operation performance of the variable speed pumped storage system are enhanced greatly. The effectiveness of the proposed low-frequency capacitor voltage fluctuation suppression method is verified through simulation results.

ABSTRACTAccumulating evidence suggests that gut microbiota as a critical mediator of gut-brain axis plays an important role in human health. Altered gut microbial profiles have been implicated in increasing the vulnerability of psychiatric disorders, such as autism, depression, and schizophrenia. However, the cellular and molecular mechanisms underlying the association remain unknown. Here, we modified the gut microbiome with antibiotics in newborn mice, and found that gut microbial alteration induced behavioral impairment by decreasing adult neurogenesis and long-term potentiation of synaptic transmission, and altering the gene expression profile in hippocampus. Reconstitution with normal gut flora produced therapeutic effects against both adult neurogenesis and behavioral deficits in the dysbiosis mice. Furthermore, our results show that circulating metabolites changes mediate the effect of gut dysbiosis on hippocampal plasticity and behavior outcomes. Elevating the serum 4-methylphenol, a small aromatic metabolite produced by gut bacteria, was found to induce autism spectrum disorder (ASD)-like behavior impairment and hippocampal dysfunction. Together our finding demonstrates that early-life gut dysbiosis and its correlated metabolites change contribute to hippocampal dysfunction and behavior impairment, hence highlight the potential microbiome-mediated therapies for treating psychiatric disorders.

We propose a strategy to improve the performance of the quantum adiabatic algorithm (QAA) on an NP-hard (nondeterministic-polynomial-time-hard) problem exact cover, by increasing the ground-state degeneracy of the problem Hamiltonian. Our strategy is based on the empirical finding that for the QAA the difficulty of random instances decreases with the degeneracy of the ground state. We increase the degeneracy by adding extra qubits to form additional clauses. Our numerical results show that on average our strategy can provide an increase in the minimum gap size along the linear interpolation path of Hamiltonian for both easy and difficult instances. The success probability at fixed total evolution time is thus increased. [ABSTRACT FROM AUTHOR]

Summary:Short chain branches distribution (SCBD) is the key factor for high density polyethylene (HDPE) pipe materials to achieve their excellent performance for long term (50 years) applications. However, the precise SCBD characterization of these HDPE materials with relatively low content of comonomer incorporation still remained as a challenge in this field. In this work, two characterization methods, namely temperature rising elution fractionation (TREF) cross step crystallization (SC) (TREF + SC) and TREF cross 13C‐NMR (TREF + 13C‐NMR), have been respectively used to qualitatively and quantitatively investigate the SCBD for two HDPE pipe materials (PE‐1 and PE‐2 with different long term performances) with small amount of 1‐hexene incorporation prepared from SiO2‐supported silyl chromate catalyst system (S‐2 catalyst) during UNIPOL gas phase polymerization. The comparison of SCBD between the two samples showed that: although short chain branches of PE‐2 with good performance were less than those of PE‐1 with bad performance, PE‐2 showed less comonomer incorporation on the low crystallinity and low molecular weight (MW) fractions keeping even higher comonomer incorporation on the high crystallinity and high MW parts compared with PE‐1. This difference on the SCBD for PE‐1 and PE‐2 was thought to be the key factor which is responsible for their great difference on environment slow crack resistance (ESCR). Moreover, TREF + SC method further reflected the intra‐ and inter‐molecular heterogeneities of each fraction from the two HDPE samples through the lamella thickness distribution compared with TREF + 13C‐NMR.

The hippocampus is a temporal lobe structure critical for cognition, such as learning, memory, and attention, as well as emotional responses. Hippocampal dysfunction can lead to persistent anxiety and/or depression. However, how millions of neurons in the hippocampus are molecularly and structurally organized to engage their divergent functions remains unknown. Here, we genetically target a subset of neurons expressing the coagulation factor c homolog(COCH) gene. COCH-expressing neurons or COCH neurons are topographically segregated in the distal region of the ventral CA3 hippocampus and express Mtf1and Cacna1h. MTF1 activation of Cacna1htranscription in COCH neurons encodes the ability of COCH neurons to burst action potentials and cause social-stress-induced anxiety-like behaviors by synapsing directly with a subset of GABAergic inhibitory neurons in the lateral septum. Together, this study provides a molecular and circuitry-based framework for understanding how COCH neurons in the hippocampus are assembled to engage social behavior.

An industrially proven method for increasing cell efficiency of monocrystalline P‐type PERC cells is reported, whereby a layer of silicon oxide or silicon oxynitride (SiOx/SiOxNy) is sandwiched between aluminum oxide (AlOx) and silicon nitride (SiNx) in the rear passivation stack, forming an AlOx+ SiOx/SiOxNy+ SiNxstructure. This additional layer will theoretically improve the rear side optical and electrical properties for the cell. By adjusting the flow ratio of N2O:NH3, SiOx/SiOxNywith different refractive indices were fabricated. Optimization of the SiOxfilm thickness showed a 0.11% efficiency gain in monofacial P‐type PERC cells because of higher short‐circuit current (Isc) and fill factor (FF), whereas optimization of the SiOxNyfilm refractive index showed a 0.05% efficiency gain in bifacial P‐type PERC cells due to the improvement of Iscand FF too. The current gain is believed to be benefited from the optimized light‐absorbing performance of the composite passivation layer structure. Furthermore, it is demonstrated that the refractive index of the SiNxcapping layer had to be tuned after the incorporation of SiOx/SiOxNyto improve the cell efficiency. A novel SiOxor SiOxNylayer is sandwiched between AlOxand SiNxin the rear passivation stack to improve the rear side optical and electrical properties for the monofacial (efficiency gain over 0.1% mainly comes from current and fill factor) and bifacial (efficiency gain over 0.05% mainly comes from current) P‐PERC solar cell.

Cardiac myocyte disarray is the pathological hallmark of hypertrophic cardiomyopathy (HCM), a disease of sarcomeric proteins. Mutations in the cardiac troponin T (cTnT), a major gene responsible for HCM, are associated with severe myocyte disarray. To study the pathogenesis of cardiac myocyte disarray, we expressed normal and mutant cTnT proteins in the myocardium of adult rabbits via direct intramyocardial injection of recombinant adenoviruses. Aliquots of 1010 plaque-forming units of normal (Ad/CMV/cTnT-Arg92) and mutant (Ad/CMV/cTnT-Gln92) recombinant viruses or a control vector (Ad/ΔE) virus were mixed with equal aliquots of a reporter virus (Ad/CMV/Lac-Z) and co-injected into the myocardium of adult rabbits (n = 12). One week following gene transfer, thin myocardial sections were obtained and analyzed for β-galactosidase, messenger RNA (mRNA) and protein expression, hematoxylin and eosin, Masson’s trichrome, immunofluorescence staining, and electron microscopy. The efficiency of gene transfer varied from 2% to 60% of the cells in an area ≈2.5 mm in length. Northern blotting confirmed expression of the transgenes into mRNA. Immunoblotting of the myofibrillar protein extracts and indirect immunofluorescence staining confirmed expression and incorporation of the transgene proteins into myofibrils. Expression of the mutant cTnT was up to 18% of the endogenous. Light and electron microscopic studies showed normal cardiac myocyte and sarcomere structures. Thus, despite incorporation of the mutant cTnT-Gln92, stable myofibrillar formation and sarcomere assembly proceeded in vivo. The absence of myocyte and sarcomere disarray may reflect the duration, or the level of expression, or the extent of myofibrillar incorporation of the mutant cTnT-Gln92, as well as the site and timing of expression of the transgenes, and interspecies variation in the pathogenesis of HCM.

Mossy cells (MCs) are a unique group of excitatory neurons in the hippocampus, a brain region important for emotion, learning, and memory. Due to the lack of a reliable method to isolate MCs from other cell types, how MCs integrate neural information and convey it to their synaptic targets for engaging a specific function are still unknown. Here, we report that MCs control the efficacy of spatial memory retrieval by synapsing directly onto local somatostatin-expressing (SST) cells. MC-SST synaptic transmission undergoes long-term potentiation (LTP), requiring Gria2-lacking Ca2+-permeable anti-α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor (Ca2+AR). A long noncoding RNA (Gria2I) is associated with Gria2 transcriptional repressors in SST cells. Silencing Gria2I induces Gria2 transcription, blocks LTP of MCs-SST synaptic transmission, and reduces the efficacy of memory retrieval. Thus, MCs directly and functionally innervate local SST neurons, and this innervation controls the efficacy of spatial memory retrieval by Gria2I inhibition of Gria2 transcription.

H2O2is predominantly used as an oxidizer in traditional metal assisted chemical etching (MACE), showing a high consumption rate due to its instability at room temperature. In this work, low concentration HNO3instead of H2O2is investigated in Ag‐assisted chemical etching process for multicrystalline silicon (mc‐Si) wafer. In comparative experiments, black silicon wafers with a surface reflection of 6.46% are obtained using HNO3with only 5% molar concentration quantity of H2O2. After a post nanostructure rebuilding treatment, nano‐scale inverted pyramid‐like structures are obtained. SEM images reveal that increase in HNO3concentration lead to an increase in surface roughness with enlarged structure size. Furthermore, a linear increase in etching rate is observed when AgNO3concentration raised from 0 to 0.8 × 10−3m. The activation energy of 95.4 eV for the HNO3/HF‐Si reaction catalyzed by Ag is obtained by Arrhenius equation. The outcomes demonstrate HNO3as a potential alternative to conventional oxidizer H2O2in traditional MACE process. In this article, the feasibility of replacing traditional H2O2by low concentration HNO3in MACE process is proved. B‐Si surface with a reflectance of 6.462% is fabricated. The increase of C(HNO3) or C(AgNO3) both leads to the raise of inverted pyramid structure size. The activation energy of Ag assisted etching reaction, 95.4 eV, is obtained using Arrhenius equation.

Quantum illumination (QI) is an entanglement-enhanced sensing system whose performance advantage over a comparable classical system survives its usage in an entanglement-breaking scenario plagued by loss and noise. In particular, QI's error-probability exponent for discriminating between equally likely hypotheses of target absence or presence is 6 dB higher than that of the optimum classical system using the same transmitted power. This performance advantage, however, presumes that the target return, when present, has known amplitude and phase, a situation that seldom occurs in light detection and ranging (lidar) applications. At lidar wavelengths, most target surfaces are sufficiently rough that their returns are speckled, i.e., they have Rayleigh-distributed amplitudes and uniformly distributed phases. QI's optical parametric amplifier receiver--which affords a 3 dB better-than-classical error-probability exponent for a return with known amplitude and phase--fails to offer any performance gain for Rayleigh-fading targets. We show that the sum-frequency generation receiver [Zhuang et al., Phys. Rev. Lett. 118, 040801 (2017)]--whose error-probability exponent for a nonfading target achieves QI's full 6 dB advantage over optimum classical operation--outperforms the classical system for Rayleigh-fading targets. In this case, QI's advantage is subexponential: its error probability is lower than the classical system's by a factor of 1/ln(MκNS/NB), when MκNS/NB≫1, with M≫1 being the QI transmitter's time-bandwidth product, NS≪1 its brightness, κ the target return's average intensity, and NB the background light's brightness. [ABSTRACT FROM AUTHOR]

Floodlight quantum key distribution (FL-QKD) is a radically different QKD paradigm that can achieve gigabit-per-second secret-key rates over metropolitan area distances without multiplexing [Q. Zhuang et al., Phys. Rev. A 94, 012322 (2016)]. It is a two-way protocol that transmits many photons per bit duration and employs a high-gain optical amplifier, neither of which can be utilized by existing QKD protocols, to mitigate channel loss. FL-QKD uses an optical bandwidth that is substantially larger than the modulation rate and performs decoding with a unique broadband homodyne receiver. Essential to FL-QKD is Alice's injection of photons from a photon-pair source--in addition to the light used for key generation--into the light she sends to Bob. This injection enables Alice and Bob to quantify Eve's intrusion and thus secure FL-QKD against collective attacks. Our proof-of-concept experiment included 10 dB propagation loss--equivalent to 50 km of low-loss fiber--and achieved a 55 Mbit/s secret-key rate (SKR) for a 100 Mbit/s modulation rate, as compared to the state-of-the-art system's 1 Mbit/s SKR for a 1 Gbit/s modulation rate [M. Lucamarini et al., Opt. Express 21, 24550 (2013)], representing ~500-fold and ~50-fold improvements in secret-key efficiency (bits per channel use) and SKR (bits per second), respectively. [ABSTRACT FROM AUTHOR]

The channel loss incurred in long-distance transmission places a significant burden on quantum key distribution (QKD) systems: they must defeat a passive eavesdropper who detects all the light lost in the quantum channel and does so without disturbing the light that reaches the intended destination. The current QKD implementation with the highest long-distance secret-key rate meets this challenge by transmitting no more than one photon per bit [M. Lucamarini et al., Opt. Express 21, 24550 (2013)]. As a result, it cannot achieve the Gbps secret-key rate needed for one-time pad encryption of large data files unless an impractically large amount of multiplexing is employed. We introduce floodlight QKD (FL-QKD), which floods the quantum channel with a high number of photons per bit distributed over a much greater number of optical modes. FL-QKD offers security against the optimum frequency-domain collective attack by transmitting less than one photon per mode and using photon-coincidence channel monitoring, and it is completely immune to passive eavesdropping. More importantly, FL-QKD is capable of a 2-Gbps secret-key rate over a 50-km fiber link, without any multiplexing, using available equipment, i.e., no new technology need be developed. FL-QKD achieves this extraordinary secret-key rate by virtue of its unprecedented secret-key efficiency, in bits per channel use, which exceeds those of state-of-the-art systems by two orders of magnitude. [ABSTRACT FROM AUTHOR]