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Molecular computing is an emerging paradigm that plays an essential role in data storage, bio-computation, and clinical diagnosis with the future trends of more efficient computing scheme, higher modularity with scaled-up circuity and stronger tolerance of corrupted inputs in a complex environment. Towards these goals, we construct a spatially localized, DNA integrated circuits-based classifier (DNA IC-CLA) that can perform neuromorphic architecture-based computation at a molecular level for medical diagnosis. The DNA-based classifier employs a two-dimensional DNA origami as the framework and localized processing modules as the in-frame computing core to execute arithmetic operations (e.g. multiplication, addition, subtraction) for efficient linear classification of complex patterns of miRNA inputs. We demonstrate that the DNA IC-CLA enables accurate cancer diagnosis in a faster (about 3 h) and more effective manner in synthetic and clinical samples compared to those of the traditional freely diffusible DNA circuits. We believe that this all-in-one DNA-based classifier can exhibit more applications in biocomputing in cells and medical diagnostics. Molecular computing is an emerging paradigm with a crucial role in clinical diagnosis. Here, authors develop a spatially localized, DNA-integrated circuits-based classifier, DNA IC-CLA, which enables accurate cancer diagnosis for clinical samples in a faster and more effective manner. [ABSTRACT FROM AUTHOR]

As a zero-carbon fuel, hydrogen is considered a promising alternative fuel. Hydrogen flames can be greatly affected by intrinsic instabilities including the diffusional-thermal instability (DTI) and Darrieus-Landau instability (DLI). Therefore, it is important to understand their properties, especially for cryogenic flames that are related to the safe utilization of liquid hydrogen. In this work, we conduct two-dimensional simulations of unsteady hydrogen/air conical flames to assess the effects of intrinsic instabilities, DTI and DLI, on the response of premixed hydrogen/air conical flames to inlet flow perturbations. The equivalence ratio and initial temperature are changed to respectively achieve different Lewis numbers (related to DTI) and expansion ratios (related to DLI). It is found that under certain conditions flame pinch-off occurs, during which a separated flame pocket is formed by the strong amplification of flame wrinkles generated by the inlet flow perturbations. The underlying mechanism of flame pinch-off enhancement due to DTI and DLI is different. For fuel-lean hydrogen/air at normal temperature, the flame front wrinkling is enhanced by strong DTI and it is the stretch-chemistry interaction that leads to flame pinch-off. However, for stoichiometric hydrogen/air at cryogenic temperature, there is a strong effect of DLI and flame pinch-off is mainly induced by flame-flow interaction. Moreover, downstream flow and flame speed near the separated flame pocket for flames exhibiting strong DTI and DLI are compared and the difference is analyzed. The findings indicate that intrinsic flame instability can amplify flame wrinkling and fluctuations in heat release rate, thereby contributing to flame pinch-off. [ABSTRACT FROM AUTHOR]

Neural Architecture Search (NAS) is a highly challenging task that requires consideration of search space, search efficiency, and adversarial robustness of the network. In this paper, to accelerate the training speed, we reformulate NAS as a multi-armed bandit problem and present Anti-Bandit NAS (ABanditNAS) method, which exploits Upper Confidence Bounds (UCB) to abandon arms for search efficiency and Lower Confidence Bounds (LCB) for fair competition between arms. Based on the presented ABanditNAS, the adversarially robust optimization and architecture search can be solved in a unified framework. Specifically, our proposed framework defends against adversarial attacks based on a comprehensive search of denoising blocks, weight-free operations, Gabor filters, and convolutions. The theoretical analysis on the rationality of the two confidence bounds in ABanditNAS are provided and extensive experiments on three benchmarks are conducted. The results demonstrate that the presented ABanditNAS achieves competitive accuracy at a reduced search cost compared to prior methods. [ABSTRACT FROM AUTHOR]

An excellent passivation technique is a crucial factor for obtaining high efficiency of solar cells. Our previous work demonstrated that a novel material strategy, using poly(4-styrenesulfonic acid) (PSS) polymer thin film, possesses high-quality passivation effect which can rival the record level of high-temperature (1000 °C) annealed SiO2. However, the thermal budget of the PSS thin film and its subsequent failure mechanism have not been reported yet. Here, PSS thin film maintains a superb passivation effect with the annealed temperatures up to 200 °C and hardly presents passivation effect with the annealed temperatures beyond 250 °C, which is similar to the thermal behavior of the industry's champion passivation material hydrogenated amorphous silicon (a-Si:H). To explain the failure mechanism, on the macro level, the surface morphology, optical and electrical performance, and thermogravimetric analysis (TGA) are investigated, and on the micro level, chemical composition and vibrational bands characteristic of the molecular of the PSS thin films are studied. This low temperature, vacuum-free and high passivation effect of silicon surfaces passivation technique has been a candidate for flexible photovoltaics, which holds great potential for reducing cost and integrating perovskite-silicon tandem solar cells. [ABSTRACT FROM AUTHOR]

The histamine receptors belong to the G protein-coupled receptor (GPCR) superfamily, and play important roles in the regulation of histamine and other neurotransmitters in the central nervous system, as potential targets for the treatment of neurologic and psychiatric disorders. Here we report the crystal structure of human histamine receptor H3R bound to an antagonist PF-03654746 at 2.6 Å resolution. Combined with the computational and functional assays, our structure reveals binding modes of the antagonist and allosteric cholesterol. Molecular dynamic simulations and molecular docking of different antihistamines further elucidate the conserved ligand-binding modes. These findings are therefore expected to facilitate the structure-based design of novel antihistamines. Crystal structure of human histamine receptor H3R bound to an antagonist PF-03654746 reveals the unexpected binding modes of the antagonist and allosteric cholesterol, which could facilitate the structure-based design of novel antihistamines. [ABSTRACT FROM AUTHOR]

Chemical sensing for the sensitive and reliable detection of mercury(II) ions (Hg2+) is of great importance in environmental protection, food safety, and biomedical applications. Due to the bio-enrichment property of Hg2+ in organisms, it is particularly meaningful to develop an effective tool that can in situ and rapidly monitor the level of Hg2+ in living organisms. In this work, we report ligand functionalized gold-silver bimetallic nanoclusters with bright red fluorescence as intracellular probes for imaging Hg2+ in living cells and zebrafish. The bimetallic nanoclusters of DTT-GSH@Au/AgNCs (DG-Au/AgNCs) with strong fluorescence that benefited from the synergistic effect of Au and Ag atoms were obtained through a one-pot synthesis method, incorporating glutathione (GSH) and dithiothreitol (DTT) as the reducers and functionalized ligands. Attractively, the bright red fluorescence of DG-Au/AgNCs could be rapidly and selectively quenched by Hg2+ within 1 min with a very low detection limit of 1.01 nM. Additionally, DG-Au/AgNCs had a great advantage in the detection of Hg2+ in living cells and zebrafish owing to its notably strong red fluorescence at 665 nm, which could avoid effectively auto-fluorescence interference from the organism. Such easily prepared bimetallic fluorescent nanoclusters would be expected to provide a noninvasive and sensitive approach in the detection of heavy metals in situ for environmental protection. [ABSTRACT FROM AUTHOR]

In recent years, addressing ill-posed problems by leveraging prior knowledge contained in databases on learning techniques has gained much attention. In this paper, we focus on complete three-dimensional (3D) point cloud reconstruction based on a single red-green-blue (RGB) image, a task that cannot be approached using classical reconstruction techniques. For this purpose, we used an encoder-decoder framework to encode the RGB information in latent space, and to predict the 3D structure of the considered object from different viewpoints. The individual predictions are combined to yield a common representation that is used in a module combining camera pose estimation and rendering, thereby achieving differentiability with respect to imaging process and the camera pose, and optimization of the two-dimensional prediction error of novel viewpoints. Thus, our method allows end-to-end training and does not require supervision based on additional ground-truth (GT) mask annotations or ground-truth camera pose annotations. Our evaluation of synthetic and real-world data demonstrates the robustness of our approach to appearance changes and self-occlusions, through outperformance of current state-of-the-art methods in terms of accuracy, density, and model completeness. [ABSTRACT FROM AUTHOR]

The ongoing pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), necessitates strategies to identify prophylactic and therapeutic drug candidates for rapid clinical deployment. Here, we describe a screening pipeline for the discovery of efficacious SARS-CoV-2 inhibitors. We screen a best-in-class drug repurposing library, ReFRAME, against two high-throughput, high-content imaging infection assays: one using HeLa cells expressing SARS-CoV-2 receptor ACE2 and the other using lung epithelial Calu-3 cells. From nearly 12,000 compounds, we identify 49 (in HeLa-ACE2) and 41 (in Calu-3) compounds capable of selectively inhibiting SARS-CoV-2 replication. Notably, most screen hits are cell-line specific, likely due to different virus entry mechanisms or host cell-specific sensitivities to modulators. Among these promising hits, the antivirals nelfinavir and the parent of prodrug MK-4482 possess desirable in vitro activity, pharmacokinetic and human safety profiles, and both reduce SARS-CoV-2 replication in an orthogonal human differentiated primary cell model. Furthermore, MK-4482 effectively blocks SARS-CoV-2 infection in a hamster model. Overall, we identify direct-acting antivirals as the most promising compounds for drug repurposing, additional compounds that may have value in combination therapies, and tool compounds for identification of viral host cell targets. Here, the authors perform repurposing screens of the ReFRAME drug library in two cell lines and identify inhibitors of SARS-CoV-2 infection. Antiviral activity of prodrug MK-4482 is confirmed in hamsters. [ABSTRACT FROM AUTHOR]

Pre-existing immunity to seasonal endemic coronaviruses could have profound consequences for antibody responses to SARS-CoV-2, induced from natural infection or vaccination. A first step to establish whether pre-existing responses can impact SARS-CoV-2 infection is to understand the nature and extent of cross-reactivity in humans to coronaviruses. Here we compare serum antibody and memory B cell responses to coronavirus spike proteins from pre-pandemic and SARS-CoV-2 convalescent donors using binding and functional assays. We show weak evidence of pre-existing SARS-CoV-2 cross-reactive serum antibodies in pre-pandemic donors. However, we find evidence of pre-existing cross-reactive memory B cells that are activated during SARS-CoV-2 infection. Monoclonal antibodies show varying degrees of cross-reactivity with betacoronaviruses, including SARS-CoV-1 and endemic coronaviruses. We identify one cross-reactive neutralizing antibody specific to the S2 subunit of the S protein. Our results suggest that pre-existing immunity to endemic coronaviruses should be considered in evaluating antibody responses to SARS-CoV-2. Pre-existing immune responses between antigenically related viruses can influence responses in viral infections or vaccinations. Here the authors assess and characterize the presence of antibody and memory B cell populations specific to SARS-CoV2 and endemic human coronaviruses. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor that plays an important role in glucose homeostasis and treatment of type 2 diabetes. Structures of full-length class B receptors were determined in complex with their orthosteric agonist peptides, however, little is known about their extracellular domain (ECD) conformations in the absence of orthosteric ligands, which has limited our understanding of their activation mechanism. Here, we report the 3.2 Å resolution, peptide-free crystal structure of the full-length human GLP-1R in an inactive state, which reveals a unique closed conformation of the ECD. Disulfide cross-linking validates the physiological relevance of the closed conformation, while electron microscopy (EM) and molecular dynamic (MD) simulations suggest a large degree of conformational dynamics of ECD that is necessary for binding GLP-1. Our inactive structure represents a snapshot of the peptide-free GLP-1R and provides insights into the activation pathway of this receptor family. Glucagon-like peptide-1 receptor (GLP-1R) plays an important role in glucose homeostasis and treatment of type 2 diabetes. Here authors report the peptide-free crystal structure of human GLP-1R in an inactive state which reveals a unique closed conformation of the extracellular domain. [ABSTRACT FROM AUTHOR]

Class B G-protein-coupled receptors (GPCRs), which consist of an extracellular domain (ECD) and a transmembrane domain (TMD), respond to secretin peptides to play a key part in hormonal homeostasis, and are important therapeutic targets for a variety of diseases. Previous work has suggested that peptide ligands bind to class B GPCRs according to a two-domain binding model, in which the C-terminal region of the peptide targets the ECD and the N-terminal region of the peptide binds to the TMD binding pocket. Recently, three structures of class B GPCRs in complex with peptide ligands have been solved. These structures provide essential insights into peptide ligand recognition by class B GPCRs. However, owing to resolution limitations, the specific molecular interactions for peptide binding to class B GPCRs remain ambiguous. Moreover, these previously solved structures have different ECD conformations relative to the TMD, which introduces questions regarding inter-domain conformational flexibility and the changes required for receptor activation. Here we report the 3.0 Å-resolution crystal structure of the full-length human glucagon receptor (GCGR) in complex with a glucagon analogue and partial agonist, NNC1702. This structure provides molecular details of the interactions between GCGR and the peptide ligand. It reveals a marked change in the relative orientation between the ECD and TMD of GCGR compared to the previously solved structure of the inactive GCGR-NNC0640-mAb1 complex. Notably, the stalk region and the first extracellular loop undergo major conformational changes in secondary structure during peptide binding, forming key interactions with the peptide. We further propose a dual-binding-site trigger model for GCGR activation-which requires conformational changes of the stalk, first extracellular loop and TMD-that extends our understanding of the previously established two-domain peptide-binding model of class B GPCRs. [ABSTRACT FROM AUTHOR]

The human glucagon receptor, GCGR, belongs to the class B G-protein-coupled receptor family and plays a key role in glucose homeostasis and the pathophysiology of type 2 diabetes. Here we report the 3.0 Å crystal structure of full-length GCGR containing both the extracellular domain and transmembrane domain in an inactive conformation. The two domains are connected by a 12-residue segment termed the stalk, which adopts a β-strand conformation, instead of forming an α-helix as observed in the previously solved structure of the GCGR transmembrane domain. The first extracellular loop exhibits a β-hairpin conformation and interacts with the stalk to form a compact β-sheet structure. Hydrogen-deuterium exchange, disulfide crosslinking and molecular dynamics studies suggest that the stalk and the first extracellular loop have critical roles in modulating peptide ligand binding and receptor activation. These insights into the full-length GCGR structure deepen our understanding of the signalling mechanisms of class B G-protein-coupled receptors. [ABSTRACT FROM AUTHOR]

Telomerase is one of the most common markers of human malignant tumors, such as uterine, stomach, esophageal, breast, colorectal, laryngeal squamous cell, thyroid, bladder, and so on. It is necessary to develop some sensitive but convenient detection methods for telomerase activity determination. In this study, a label-free and ultrasensitive electrochemiluminescence (ECL) biosensor has been fabricated to detect the activity of telomerase extracted from HeLa cells. Thiolated telomerase substrate (TS) primer was immobilized on the gold electrode surface through gold-sulfur (Au-S) interaction and then elongated by telomerase specifically. Then, it was hybridized with complementary DNA to form double-stranded DNA (dsDNA) fragments on the electrode surface, and Ru(phen) has been intercalated into the dsDNA grooves to act as the ECL probe. The enhanced ECL intensity has a linear relationship with the number of HeLa cells in the range of 5∼5000 and with a detection limit of 2 HeLa cells. The proposed ECL biosensor has high specificity to telomerase in the presence of common interferents. The relative standard deviations (RSDs) were <5 % at 100 HeLa cells. The proposed method provides a convenient approach for telomerase-related cancer screening or diagnosis. [ABSTRACT FROM AUTHOR]

Finding new applications for existing pharmaceuticals, known as drug repositioning, is a validated strategy for resolving the problem of high expenditure but low productivity in drug discovery. Currently, the prevalent computational methods for drug repositioning are focused mainly on the similarity or relevance between known drugs based on their 'features', including chemical structure, side effects, gene expression profile, and/or chemical-protein interactome. However, such drug-oriented methods may constrain the newly predicted functions to the pharmacological functional space of the existing drugs. Clinically, many drugs have been found to bind 'off-target' (i.e. to receptors other than their primary targets), which can lead to undesirable effects. In this study, which integrates known drug target information, we propose a disease-oriented strategy for evaluating the relationship between drugs and disease based on their pathway profile. The basic hypothesis of this method is that drugs exerting a therapeutic effect may not only directly target the disease-related proteins but also modulate the pathways involved in the pathological process. Upon testing eight of the global best-selling drugs in 2010 (each with more than three targets), the FDA (Food and Drug Administration, USA)-approved therapeutic function of each was included in the top 10 predicted indications. On average, 60% of predicted results made using our method are proved by literature. This approach could be used to complement existing methods and may provide a new perspective in drug repositioning and side effect evaluation. [ABSTRACT FROM AUTHOR]

Investigation of the potential therapeutic mechanisms of drug candidates is an essential step in the process of new drug discovery. With the rapid development of systems biology, recent network analyses of proteins, drugs, and diseases have enabled great progress in delineating the molecule mechanisms of drug candidates. However, most analyses perform a direct association between gene/protein and disease levels without considering the intermediate biological pathways regulated by the drugs. Given that a protein performs its biological roles through pathways, we propose using a novel pathway-pathway network analysis to investigate the potential therapeutic functions of the drug candidates. Many studies have demonstrated that salvianolic acid B (Sal B) of Salvia miltiorrhiza is an effective therapy for cardiovascular diseases (CVD). Using molecular docking methods to identify direct interacting targets of Sal B, we collected all Sal B-regulated proteins with supporting experimental evidence in PubMed abstracts. FDA-approved CVD drugs and their corresponding targets were also collected. From a traditional drug-protein network analysis, we found that Sal B could affect ACE and REN of the renin-angiotensin-aldosterone system to relax vessels and alleviate hypertension. Subsequent pathway-pathway network analysis was attempted to study the mechanisms of Sal B in treating CVD, and demonstrated that Sal B regulates immunity/inflammation, apoptosis, ion transport and basic metabolism processes in the treatment of CVD. Regulating the immune/inflammation process may be the major mechanism of Sal B. We believe that pathway-pathway network analysis is a novel method for studying the therapeutic mechanisms of herbal ingredients. [ABSTRACT FROM AUTHOR]

The recrystallization of β-Sn profoundly affects deformation and failure of Sn-Ag-Cu solder joints in thermomechanical fatigue (TMF) testing. The numerous grain boundaries of recrystallized β-Sn enable grain boundary sliding, which is absent in as-solidified solder joints. Fatigue cracks initiate at, and propagate along, recrystallized grain boundaries, eventually leading to intergranular fracture. The recrystallization behavior of Sn-Ag-Cu solder joints was examined in three different TMF conditions for five different ball grid array component designs. Based on the experimental observations, a TMF damage accumulation model is proposed: (1) strain-enhanced coarsening of secondary precipitates of AgSn and CuSn starts at joint corners, eventually allowing recrystallization of the Sn grain there as well; (2) coarsening and recrystallization continue to develop into the interior of the joints, while fatigue crack growth lags behind; (3) fatigue cracks finally progress through the recrystallized region. Independent of the TMF condition, the recrystallization appeared to be essentially complete after somewhat less than 50% of the characteristic life, while it took another 50% to 75% of the lifetime for a fatigue crack to propagate through the recrystallized region. [ABSTRACT FROM AUTHOR]

mTOR signaling pathway is deregulated in most cancers and uncontrolled cell cycle progression is a hallmark of cancer cell. However, the precise molecular mechanisms of the regulation of DNA replication and chromatin metabolism by mTOR signaling are largely unknown. We herein report that mTOR signaling promotes the loading of MCM2-7 helicase onto chromatin and upregulates DNA replication licensing factor CDC6. Pharmacological inhibition of mTOR kinase resulted in CHK1 checkpoint activation and decreased MCM2-7 replication helicase and PCNA associated with chromatins. Further pharmacological and genetic studies demonstrated CDC6 is positively controlled by mTORC1-S6K1 and mTORC2 signaling. miRNA screening revealed mTOR signaling suppresses miR-3178 thereby upregulating CDC6. Analysis of TCGA data found that CDC6 is overexpressed in most cancers and associates with the poor survival of cancer patients. Our findings suggest that mTOR signaling may control DNA replication origin licensing and replisome stability thereby cell cycle progression through CDC6 regulation. [ABSTRACT FROM AUTHOR]

The Yiyuan hominin fossil site is one of the few localities in China where a partial skullcap and several loose teeth of Homo erectus have been discovered. Yiyuan was previously assigned broadly to the Middle Pleistocene by biostratigraphical correlation and ESR/U-series dating. Here, we report the first application of a radio-isotopic dating method to the site. 26Al/10Be burial dating results derived from two sand samples from the fossiliferous deposits show that the hominin fossils can be confidently dated to 0.64 ± 0.08 Ma (million years ago). The reliability of this age is supported by the zero age of modern fluvial sediment near the cave. Our result is consistent with the age estimation based on biostratigraphic correlation and supports the argument that the Yiyuan and Zhoukoudian Locality 1 H. erectus fossils are contemporaneous. The results presented here, along with other recent chronological studies on Chinese Middle Pleistocene hominin sites, indicate that the time span from 600–400 ka (thousand years ago) is a critical period for human evolution in East Asia. Importantly, this time bracket includes several major climatic changes that would have influenced hominins, both morphologically and behaviorally. [ABSTRACT FROM AUTHOR]

Three genome-wide association studies (GWAS) have been conducted on the genetic susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), two of which consistently identified tagging single nucleotide polymorphisms (SNPs) around HLA-DQ/DR. In contrast, large multi-centre association studies between HBV genotype, mutations and the risk of HCC are relatively rare, and their interactions with host variants are even less. We performed a multi-centre study of 1,507 HBV-related HCC cases and 1,560 HBV persistent carriers as controls to evaluate the effects of HBV genotype, mutations, GWAS-identified HLA-DQ/DR SNPs (rs9272105 and rs9275319) and their interactions on HCC risk. We found HBV genotype C was more frequent in HBV-related HCC. And 11 HBV hotspot mutations were independently and significantly associated with HCC risk. We also detected significant interactions of rs9272105 with both the HBV genotype and mutations. Through stepwise regression analysis, HBV genotype, the 11 mutations, HLA-DQ/DR SNPs, and the interaction of rs9272105 with mutation A1752G were all entered into the HCC prediction model, and the area under the curve for the panel including the HLA-DQ/DR SNPs, HBV genotype and mutations was 0.840. The HBV genotype, the mutations and the HLA-DQ/DR SNPs may serve as biomarkers for the surveillance of HBV persistent carriers. [ABSTRACT FROM AUTHOR]

Traditional Chinese Medicine (TCM) treatment has been commonly used to treat Chronic Hepatitis B (CHB) in Asian countries based on TCM syndrome diagnosis, also called 'ZHENG'. The syndrome is identified through the four-diagnostic methods, with certain degree of subjectivity and ambiguity from individual doctors. Normally those CHB patients also receive series of parameters from modern clinical examination, while they are routinely believed to be unrelated with the TCM syndrome diagnosis. In this study, we investigated whether these biomedical indexes in modern medicine could be beneficial to TCM syndrome diagnostics in an integrative way. Based on 634 patient samples from health controls and three subtypes of CHB syndromes, a two-view based hierarchical classification model was tested for TCM syndromes prediction based on totally 222 parameters integrated from both TCM practice and modern clinical tests. The results indicated that the performance of syndrome classification based on a proper integration of TCM and modern clinical indexes was significantly higher than those based on one view of parameters only. Furthermore, those indexes correlated with CHB syndrome diagnosis were successfully identified for CM indexes and biochemical indexes respectively, where potential associations between them were hinted to the MAPK signaling pathway. [ABSTRACT FROM AUTHOR]