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Brain ventricular and subcortical structures are heritable both in size and shape. Genetic influences on brain region size have been studied using conventional volumetric measures, but little is known about the genetic basis of ventricular and subcortical shapes. Here we developed pipelines to extract seven complementary shape measures for lateral ventricles, subcortical structures, and hippocampal subfields. Based on over 45,000 subjects in the UK Biobank and ABCD studies, 60 genetic loci were identified to be associated with brain shape features (P < 1.09 × 10-10), 19 of which were not detectable by volumetric measures of these brain structures. Ventricular and subcortical shape features were genetically related to cognitive functions, mental health traits, and multiple brain disorders, such as the attention-deficit/hyperactivity disorder. Vertex-based shape analysis was performed to precisely localize the brain regions with these shared genetic influences. Mendelian randomization suggests brain shape causally contributes to neurological and neuropsychiatric disorders, including Alzheimer’s disease and schizophrenia. Our results uncover the genetic architecture of brain shape for ventricular and subcortical structures and prioritize the genetic factors underlying disease-related shape variations.

Early dietary exposure via human milk nutrients offers a window of opportunity to support cognitive and temperament development. While several studies have focused on associations of few pre-selected human milk nutrients with cognition and temperament, it is highly plausible that human milk nutrients synergistically and jointly support cognitive and behavioral development in early life. We aimed to discern the combined associations of three major classes of human milk nutrients with cognition and temperament during the first 6 months of life when human milk is the primary source of an infant’s nutrition and explore whether there were persistent effects up to 18 months old. The Mullen Scales of Early Learning and Infant Behavior Questionnaires—Revised were used to assess cognition and temperament, respectively, of 54 exclusively/predominantly breastfed infants in the first 6 months of life, whose follow-ups were conducted at 6–9, 9–12, and 12–18 months old. Human milk samples were obtained from the mothers of the participants at less than 6 months of age and analyzed for fatty acids [total monounsaturated fatty acids, polyunsaturated fatty acid, total saturated fatty acid (TSFA), arachidonic acid (ARA), docosahexaenoic acid (DHA), ARA/DHA, omega-6/omega-3 polyunsaturated fatty acids ratio (n-6/n-3)], phospholipids [phosphatidylcholine, phosphatidylethanolamine (PE), phosphatidylinositol (PI), sphingomyelin], and choline [free choline, phosphocholine (PCho), glycerophosphocholine]. Feature selection was performed to select nutrients associated with cognition and temperament. The combined effects of selected nutrients were analyzed using multiple regression. A positive association between the arachidonic acid (ARA) and surgency was observed (p = 0.024). A significant effect of DHA, n-6/n-3, PE, and TSFA concentrations on receptive language (R2 = 0.39, p = 0.025) and the elevated ARA, PCho, and PI with increased surgency (R2 = 0.43, p = 0.003) was identified, suggesting that DHA and ARA may have distinct roles for temperament and language functions. Furthermore, the exploratory association analyses suggest that the effects of human milk nutrients on R.L. and surgency may persist beyond the first 6 months of life, particularly surgency at 12–18 months (p = 0.002). Our study highlighted that various human milk nutrients work together to support the development of cognition and temperament traits during early infancy.

A new global potential energy surface (PES) for the ground state of the SH2+(X4A′′) system is constructed using a permutation invariant polynomial neural network method. In ab initio calculations, the MRCI-F12 method with the AVTZ basis set is used. Furthermore, the dynamics calculations of the S+ + H2(v = 0–3, j = 0) → SH+ + H reaction are carried out based on the new PES. The reaction probabilities and integral cross sections are compared with available theoretical calculations. Present values are in general good agreement with the previous theoretical studies. However, some discrepancies can still be found due to different PESs used in the calculation. Furthermore, the vibrational energy of the reactant molecule can significantly enhance the reactivity compared to the translational energy. The differential cross sections indicated that the reaction mechanism is changed from the “head-on” rebound mechanism to the tripping mechanism with the increasing number of initial vibrational excitation state.

Early dietary exposure via human milk (HM) components offers a window of opportunity to support cognitive and temperamental development. While several studies have focused on associations of few pre-selected HM components with cognition and temperament, it is highly plausible that HM components synergistically and jointly support cognitive and behavioral development in early life. We aimed to discern the combined associations of a wide array of HM nutrients with cognition and temperament during the first six months of life and explore if there were persistent effects up to 18 months old, when HM is the primary source of an infant’s nutrition. The Mullen Scales of Early Learning and Infant Behavior Questionnaires-Revised were used to assess cognition and temperament, respectively, of fifty-four exclusively/predominantly breastfed infants in the first 6 months of life, whose follow-ups were conducted at 6-9, 9-12 and 12-18 months old. HM samples were obtained from the mothers of the participants at less than 6 months of life and analyzed for fatty acids (total monounsaturated fatty acids, polyunsaturated fatty acid, total saturated fatty acid (TSFA), arachidonic acid (ARA), docosahexaenoic acid (DHA), ARA/DHA, omega-6/omega-3 polyunsaturated fatty acids ratio (n-6/n-3)), phospholipids (phosphatidylcholine, phosphatidylethanolamine (PE), phosphatidylinositol (PI), sphingomyelin) and choline (free choline, phosphocholine (PCho), glycerophosphocholine). Feature selection was performed to select nutrients associated with cognition and temperament, respectively. The combined effects of selected nutrients were analyzed using multiple regression. A positive association between the arachidonic acid (ARA) and surgency was observed (p = 0.024). Significant effect of DHA, n-6/n-3, PE and TSFA concentrations on receptive language (R2 = 0.39, p = 0.025), and the elevated ARA, PCho, and PI with increased surgency (R2 = 0.43, p = 0.003) was identified, suggesting that DHA and ARA may have distinct roles for temperament and language functions. Furthermore, the exploratory association analyses suggest that the effects of HM nutrients on R.L. and surgency may persist beyond the first 6 months of life, particularly surgency at 12-18 months (p = 0.002). Our studies highlighted that various HM nutrients work together to support the development of cognition and temperament traits during early infancy.

Prenatal opioid exposure has been linked to adverse effects spanning multiple neurodevelopmental domains, including cognition, motor development, attention, and vision. However, the neural basis of these abnormalities is largely unknown. A total of 49 infants, including 21 opioid-exposed and 28 controls, were enrolled and underwent MRI (43 ± 6 days old) after birth, including resting state functional MRI. Edge-centric functional networks based on dynamic functional connections were constructed, and machine-learning methods were employed to identify neural features distinguishing opioid-exposed infants from unexposed controls. An accuracy of 73.6% (sensitivity 76.25% and specificity 69.33%) was achieved using 10 times 10-fold cross-validation, which substantially outperformed those obtained using conventional static functional connections (accuracy 56.9%). More importantly, we identified that prenatal opioid exposure preferentially affects inter- rather than intra-network dynamic functional connections, particularly with the visual, subcortical, and default mode networks. Consistent results at the brain regional and connection levels were also observed, where the brain regions and connections associated with visual and higher order cognitive functions played pivotal roles in distinguishing opioid-exposed infants from controls. Our findings support the clinical phenotype of infants exposed to opioids in utero and may potentially explain the higher rates of visual and emotional problems observed in this population. Finally, our findings suggested that edge-centric networks could better capture the neural differences between opioid-exposed infants and controls by abstracting the intrinsic co-fluctuation along edges, which may provide a promising tool for future studies focusing on investigating the effects of prenatal opioid exposure on neurodevelopment.

Cardiovascular health interacts with cognitive and psychological health in complex ways. Yet, little is known about the phenotypic and genetic links of heart-brain systems. Using cardiac and brain magnetic resonance imaging (CMR and brain MRI) data from over 40,000 UK Biobank subjects, we developed detailed analyses of the structural and functional connections between the heart and the brain. CMR measures of the cardiovascular system were strongly correlated with brain basic morphometry, structural connectivity, and functional connectivity after controlling for body size and body mass index. The effects of cardiovascular risk factors on the brain were partially mediated by cardiac structures and functions. Using 82 CMR traits, genome-wide association study identified 80 CMR-associated genomic loci (P < 6.09 × 10-10), which were colocalized with a wide spectrum of heart and brain diseases. Genetic correlations were observed between CMR traits and brain-related complex traits and disorders, including schizophrenia, bipolar disorder, anorexia nervosa, stroke, cognitive function, and neuroticism. Our results reveal a strong heart-brain connection and the shared genetic influences at play, advancing a multi-organ perspective on human health and clinical outcomes.

The human cerebral cortex plays a crucial role in brain functions. However, genetic influences on the human cortical functional organizations are not well understood. Using a parcellation-based approach with resting-state and task-evoked functional magnetic resonance imaging (fMRI) from 40,253 individuals, we identified 47 loci associated with functional areas and networks at rest, 15 of which also affected the functional connectivity during task performance. Heritability and locus-specific genetic effects patterns were observed across different brain functional areas and networks. Specific functional areas and networks were identified to share genetic influences with cognition, mental health, and major brain disorders (such as Alzheimer’s disease and schizophrenia). For example, in both resting and task fMRI, the APOE ε4 locus strongly associated with Alzheimer’s disease was particularly associated with the visual cortex in the secondary visual and default mode networks. In summary, by analyzing biobank-scale fMRI data in high-resolution brain parcellation, this study advances our understanding of the genetic determinants of cerebral cortex function and prioritizes genetically associated fMRI traits for clinical applications of specific brain disorders.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood, and is often characterized by altered executive functioning. Executive function has been found to be supported by flexibility in dynamic brain reconfiguration. Thus, we applied multilayer community detection to resting-state fMRI data in 180 children with ADHD and 180 typically developing children (TDC) to identify alterations in dynamic brain reconfiguration in children with ADHD. We specifically evaluated MR derived neural flexibility, which is thought to underlie cognitive flexibility, or the ability to selectively switch between mental processes. Significantly decreased neural flexibility was observed in the ADHD group at both the whole brain (raw p = 0.0005) and sub-network levels (p p = 0.025, FDR corrected) when compared to subjects with ADHD who were medication naïve, and their neural flexibility was not statistically different from the TDC group (p = 0.74, FDR corrected). Finally, regional neural flexibility was capable of differentiating ADHD from TDC (Accuracy: 77% for tenfold cross-validation, 74.46% for independent test) and of predicting ADHD severity using clinical measures of symptom severity (R2: 0.2794 for tenfold cross-validation, 0.156 for independent test). In conclusion, the present study found that neural flexibility is altered in children with ADHD and demonstrated the potential clinical utility of neural flexibility to identify children with ADHD, as well as to monitor treatment responses and disease severity.

Brain regions communicate with each other via tracts of myelinated axons, commonly referred to as white matter. White matter microstructure can be measured in the living human brain using diffusion based magnetic resonance imaging (dMRI), and has been found to be altered in patients with neuropsychiatric disorders. Although under strong genetic control, few genetic variants influencing white matter microstructure have ever been identified. Here we identified common genetic variants influencing white matter microstructure using dMRI in 42,919 individuals (35,741 in the UK Biobank). The dMRIs were summarized into 215 white matter microstructure traits, including 105 measures from tract-specific functional principal component analysis. Genome-wide association analysis identified many novel white matter microstructure associated loci (P< 2.3 × 10−10). We identified shared genetic influences through genetic correlations between white matter tracts and 62 other complex traits, including stroke, neuropsychiatric disorders (e.g., ADHD, bipolar disorder, major depressive disorder, schizophrenia), cognition, neuroticism, chronotype, as well as non-brain traits. Common variants associated with white matter microstructure alter the function of regulatory elements in glial cells, particularly oligodendrocytes. White matter associated genes were enriched in pathways involved in brain disease pathogenesis, neurodevelopment process, and repair of white matter damage (P< 1.5 × 10−8). In summary, this large-scale tract-specific study provides a big step forward in understanding the genetic architecture of white matter and its genetic links to a wide spectrum of clinical outcomes.

Individual variations of white matter (WM) tracts are known to be associated with various cognitive and neuropsychiatric traits. Diffusion tensor imaging (DTI) and genome-wide single-nucleotide polymorphism (SNP) data from 17,706 UK Biobank participants offer the opportunity to identify novel genetic variants of WM tracts and explore the genetic overlap with other brain-related complex traits. We analyzed the genetic architecture of 110 tract-based DTI parameters, carried out genome-wide association studies (GWAS), and performed post-GWAS analyses, including association lookups, gene-based association analysis, functional gene mapping, and genetic correlation estimation. We found that DTI parameters are substantially heritable for all WM tracts (mean heritability 48.7%). We observed a highly polygenic architecture of genetic influence across the genome (p value = 1.67 × 10−05) as well as the enrichment of genetic effects for active SNPs annotated by central nervous system cells (p value = 8.95 × 10−12). GWAS identified 213 independent significant SNPs associated with 90 DTI parameters (696 SNP-level and 205 locus-level associations; p value

Latent thermal energy storage has been recommended as an effective technique to the thermal management system of space exploration due to its excellent ability of storing thermal energy. In the current work, the melting process of phase change material under supergravity conditions (3g, 5g, 7g) are numerically investigated by a pore-scale lattice Boltzmann method with the real microstructure of metal foam. A comparative study is carried out to illustrate the influence of gravitational acceleration and metal foam on melting performance of phase change material. Results indicate that natural convection accelerates the motion velocity of the upper PCM, and leads to the inhomogeneous distribution of melting front. Moreover, with the increasing gravitational acceleration, there is a transition of the dominated heat transfer mechanism from conduction to convection, which attributes to the stepped-up natural convection effect, and thus melting front gets even steeper and melting rate is significantly increased. Besides, the existence of metal foam significantly distorts the melting front and enhances the melting rate.

Based on Yuan’s potential energy surface (PES) (Sci. Rep. 5, 14594 (2015)), the $$\hbox {S}(^{1}\hbox {D}) + \hbox {HD}$$ reaction are studied using time-dependent quantum method in the collision energy range 0.001-1.0 eV. The dynamic results of the $$\hbox {S}(^{1}\hbox {D}) + \hbox {HD}$$ reaction, such as reaction probability, integral cross sections (ICSs), differential cross sections (DCSs) and rate constant, are calculated at state-to-state level of theory. ICSs and thermal rate constants are compared with available experimental data. The results indicated that present values are in general good agreement with the experimental data. The DCSs of the two channels are forward–backward symmetric in the collision energy range investigated. This implies that complex-forming reaction mechanism plays a dominant role in the reaction and the statistical model is suitable for the $$\hbox {S}(^{1}\hbox {D}) + \hbox {HD}$$ reaction. The rate constants of these two channels are not sensitive to the temperature.

A new global potential energy surface (PES) for the ground state of the SH2+(X4A'') system is constructed using a permutation invariant polynomial neural network method. In ab initio calculations, the MRCI-F12 method with the AVTZ basis set is used. Furthermore, the dynamics calculations of the S+ + H2(v = 0-3, j = 0) → SH+ + H reaction are carried out based on the new PES. The reaction probabilities and integral cross sections are compared with available theoretical calculations. Present values are in general good agreement with the previous theoretical studies. However, some discrepancies can still be found due to different PESs used in the calculation. Furthermore, the vibrational energy of the reactant molecule can significantly enhance the reactivity compared to the translational energy. The differential cross sections indicated that the reaction mechanism is changed from the "head-on" rebound mechanism to the tripping mechanism with the increasing number of initial vibrational excitation state.

Less than 35% of recyclable waste is being actually recycled in the US, which leads to increased soil and sea pollution and is one of the major concerns of environmental researchers as well as the common public. At the heart of the problem are the inefficiencies of the waste sorting process (separating paper, plastic, metal, glass, etc.) due to the extremely complex and cluttered nature of the waste stream. Recyclable waste detection poses a unique computer vision challenge as it requires detection of highly deformable and often translucent objects in cluttered scenes without the kind of context information usually present in human-centric datasets. This challenging computer vision task currently lacks suitable datasets or methods in the available literature. In this paper, we take a step towards computer-aided waste detection and present the first in-the-wild industrial-grade waste detection and segmentation dataset, ZeroWaste. We believe that ZeroWaste will catalyze research in object detection and semantic segmentation in extreme clutter as well as applications in the recycling domain. Our project page can be found at http://ai.bu.edu/zerowaste/.

Titanium-nickel shape memory alloy (SMA) has good biomedical application value as an implant. Alloy corrosion will promote the release of toxic nickel ions and cause allergies and poisoning of cells and tissues. With this background, surface modification of TiNi SMAs using TiC-powder-assisted micro-electrical discharge machining (EDM) was proposed. This aims to explore the effect of the electrical discharge machining (EDM) parameters and TiC powder concentration on the machining properties and surface characteristics of the TiNi SMA. It was found that the material removal rate (MRR), surface roughness, and thickness of the recast layer increased with an increase in the discharge energy. TiC powder&rsquo, s addition had a positive effect on increasing the electro-discharge frequency and MRR, reducing the surface roughness, and the maximum MRR and the minimum surface roughness occurred at a mixed powder concentration of 5 g/L. Moreover, the recast layer had good adhesion and high hardness due to metallurgical bonding. XRD analysis found that the machined surface contains CuO2, TiO2, and TiC phases, contributing to an increase in the surface microhardness from 258.5 to 438.7 HV, which could be beneficial for wear resistance in biomedical orthodontic applications.

Background Genetic polymorphisms leading to variations in human milk oligosaccharide (HMO) composition have been reported. Alpha-Tetrasaccharide (A-tetra), an HMO, has been shown to only be present (>limit of detection; A-tetra+) in the human milk (HM) of women with blood type A, suggesting genetic origins determining the presence or absence (A-tetra-) of A-tetra in HM. Objectives This study aimed to determine whether associations exist between HMO concentrations and cognitive development, and whether the associations vary between A-tetra+ and A-tetra- groups in children (

The human brain remains active in the absence of explicit tasks and forms networks of correlated activity. Resting-state functional magnetic resonance imaging (rsfMRI) measures brain activity at rest, which has been linked with both cognitive and clinical outcomes. The genetic variants influencing human brain function are largely unknown. Here we utilized rsfMRI from 44,190 individuals of multiple ancestries (37,339 in the UK Biobank) to discover and validate the common genetic variants influencing intrinsic brain activity. We identified hundreds of novel genetic loci associated with intrinsic functional signatures (P< 2.8 × 10−11), including associations to the central executive, default mode, and salience networks involved in the triple network model of psychopathology. A number of intrinsic brain activity associated loci colocalized with brain disorder GWAS (e.g., Alzheimer’s disease, Parkinson’s disease, schizophrenia) and cognition, such as 19q13.32, 17q21.31, and 2p16.1. Particularly, we detected a colocalization between one (rs429358) of the two variants in theAPOEε4 locus and function of the default mode, central executive, attention, and visual networks. Genetic correlation analysis demonstrated shared genetic influences between brain function and brain structure in the same regions. We also detected significant genetic correlations with 26 other complex traits, such as ADHD, major depressive disorder, schizophrenia, intelligence, education, sleep, subjective well-being, and neuroticism. Common variants associated with intrinsic brain activity were enriched within regulatory element in brain tissues.

Quantum dynamical calculations of the H + LiH+ → Li+ + H2 reaction were performed based on the potential energy surface (PES) reported by Dong et al. (RSC Adv. 7, 7008 (2017)) using the time-depend...

The effects of the rovibrational excitation of reactants in the N(2D) + D2(X1Σg+) → ND(X3Σ+) + D(2S) reaction are calculated in a collision energy range from the threshold to 1.0 eV using the time-...

A new potential energy surface (PES) of the ground state (X2A′) of Li2H was built using 18,403 ab initio points. The MRCI-F12 method with AVQZ basis set were used in the ab initio calculation. Furthermore, the widely used permutation invariant polynomial neural network method was adopted in the fitting process. The features of new PES were compared with previous theoretical and experimental studies. The results indicated that the spectroscopic parameters of PES are in good agreement with experimental data. In addition, the dynamics calculations of the H + Li2 → Li + LiH reaction were carried out using time-dependent wave packet method based on the new PES. The dynamics properties such as reaction probability, integral cross section and thermal rate constant were reported and compared with previous theoretical studies.

The time-dependent wave packet method with a second order split operator is employed to study the state-to-state resolved reaction dynamics of the H + Li2 system. The dynamics properties, such as reaction probability, integral cross-section, differential cross-section and the rovibrational state distribution of the product are fully calculated in the present work. Both forward and backward scattering signals peaked at two extreme angles, indicating that the insert reaction mechanism plays an important role and that the statistic model is highly suitable to assess the reaction dynamics H + Li2.

Structural and microstructural variations of human brain are heritable and highly polygenic traits, with hundreds of associated genes founded in recent genome-wide association studies (GWAS). Using gene expression data, transcriptome-wide association studies (TWAS) can prioritize these GWAS findings and also identify novel gene-trait associations. Here we performed TWAS analysis of 211 structural neuroimaging phenotypes in a discovery-validation analysis of six datasets. Using a cross-tissue approach, TWAS discovered 204 associated genes (86 new) exceeding Bonferroni significance threshold of 1.37*10−8(adjusted for testing multiple phenotypes) in the UK Biobank (UKB) cohort, and validated 18 TWAS or previous GWAS-detected genes. The TWAS-significant genes of brain structures had been linked to a wide range of complex traits in different domains. Additional TWAS analysis of 11 cognitive and mental health traits detected 69 overlapping significant genes with brain structures, further characterizing the genetic overlaps among these brain-related traits. Through TWAS gene-based polygenic risk scores (PRS) prediction, we found that TWAS PRS gained substantial power in association analysis compared to conventional variant-based PRS, and up to 6.97% of phenotypic variance (p-value=7.56*10−31) in testing datasets can be explained by UKB TWAS-derived PRS. In conclusion, our study illustrates that TWAS can be a powerful supplement to traditional GWAS in imaging genetics studies for gene discovery-validation, genetic co-architecture analysis, and polygenic risk prediction.

Volumetric variations of human brain are heritable and are associated with many brain-related complex traits. Here we performed genome-wide association studies (GWAS) of 101 brain volumetric phenotypes using the UK Biobank (UKB) sample including 19,629 participants. GWAS identified 365 independent genetic variants exceeding significance threshold of 4.9 × 10−10, adjusted for testing multiple phenotypes. Gene-based association study found 157 associated genes (124 new), and functional gene mapping analysis linked 146 additional genes. Many of the discovered genetic variants and genes have previously been implicated in cognitive and mental health traits. Using genome-wide polygenic risk score prediction, more than 6% of phenotypic variance (P = 3.13 × 10−24) in four other independent studies could be explained by the UKB GWAS results. In conclusion, our study identifies many new genetic associations at variant, locus and gene levels and advances our understanding of the pleiotropy and genetic co-architecture between brain volumes and other traits., Editorial summary: Genome-wide analyses in 19,629 individuals identify 365 independent variants associated with brain volumetric phenotypes. The study provides insight into the overlapping genetic architecture of brain volume measures and cognitive and mental health traits.

First-principles calculations are used to investigate electronic and field emission characteristics of (5, 5) capped BeO nanotubes (BeONTs), which indicate that their emission currents under external electric fields are close to those of carbon nanotubes, and decagons on their apexes are the most probable positions for electron emission. In addition, work functions of the (5, 5) BeONTs decrease linearly with applied electric fields. The remarkable influence of lithium adsorption on their field emission characteristics is also investigated. Their work functions decline distinctly after lithium adsorption, while the emission currents have been improved by more than one order of magnitude. Moreover, there is a polynomial relationship between the total currents and the external fields.

The equilibrium structure, spectroscopy constants, and anharmonic force field of silver hydrosulfide (AgSH) have been calculated at B3P86, B3PW91 and MP2 methods employing two basis sets, TZP and QZP, respectively. The calculated geometries, ground state rotational constants, harmonic vibrational wave numbers, and quartic and sextic centrifugal distortion constants are compared with the available experimental and theoretical data. The equilibrium rotational constants, fundamental frequencies, anharmonic constants, and vibration-rotation interaction constants, Coriolis coupling constants, cubic and quartic force constants are predicted. The calculated results show that the MP2/TZP results are in good agreement with experiment observation and are also an advisable choice to study the anharmonic force field of AgSH.

Large eddy simulation is performed to investigate the mixing characteristics between the hot and cold fluids in a T-junction with different amplitudes and periods of inlet velocity. The distributions of temperature field and velocity field as well as the properties of vortex structures are focused in the present study. In addition, the wavelet power spectrum density (WPSD) of both temperature and velocity fluctuations are investigated by wavelet transform. The results show that the instantaneous temperature and velocity in the mixing area vary periodically, while the variation period is the same as that of inlet velocity. A typical phenomenon is observed near the moment of lowest inlet velocity, the backflow occurs near the upstream of the opposite wall of the jet entrance. Moreover, the WPSD results show that both mixing velocity and temperature fluctuations have the identical prominent frequency which is equal to that of inlet velocity. The period of inlet velocity has a large effect on the WPSDs of velocity and temperature fluctuations in the low frequency region, while does the amplitude of inlet velocity in the high frequency region. In addition, the effect of either period or amplitude on velocity fluctuations is not synchronized with that of temperature fluctuations.

The dynamics studies of the abstraction and exchange channels of the H + DBr and D + HBr reactions are carried out based on the potential energy surface reported by Li et al. (J. Chem. Phys. 2019, 151: 185102) in the collision energy range from 0.001 to 2.0 eV. The dynamics properties such as reaction probability, integral cross section, differential cross section, the ro-vibrational state distribution of products, specific-state rate constants, etc. are reported at state-to-state level of theory and compared with available theoretical and experimental values. The results indicate that present values are in general good agreement with experimental data for both H + DBr and D + HBr reactions. Furthermore, the isotopic and quantum tunneling effects are discussed. The differential cross sections reflect that the direct abstract mechanism plays a dominant role in the abstraction reactions and head-on “rebound” mechanism dominates the exchange reactions.

Printed circuit heat exchangers (PCHEs) have attracted wide attention in the nuclear energy field owing to their high compactness, strong pressure endurance, and high heat transfer capacity. In situations where corrosion resistance or light weight is required, PCHEs made of titanium exhibit obvious advantages. However, the corrosion resistance of titanium is so high that it is hard to machining titanium using common chemical etching method. Also, etching methods to fabricate fluid channels on titanium plates for microchannel plate heat exchangers such as PCHEs have not been reported in the open literature, therefore the research of producing fluid channels on titanium plates using etching method for PCHEs is demanded. In this work, an electrochemical etching experimental system was established, and the electrolytic machining process using NaCl-containing ethylene glycol as an electrolyte for preparing PCHE fluid channels on titanium plates was studied. To improve the corrosion rate, ultrasonic transducers were added to the experimental system. The influences of the etching temperature and ultrasonic exposure were examined with respect to the etching rate and surface topography. The results showed that ultrasonic transducers with a rated power of 120 W and a frequency of 50 kHz can enhance the corrosion rate by a factor of 4–5 and that the growth trend of the etching rate can be improved with increasing etching temperature. An etching temperature of 45 °C leads to the best comprehensive performance under ultrasonic exposure in terms of etching rate, roughness, and etching factor. Two improved methods including secondary polishing method and pulsed electrode method are proposed to maintain the quality of the surface profile when the etching rate is enhanced.

The effects of inlet temperature difference between the main and branch fluids on the flow and thermal mixing characteristics in the T-junction under inflow pulsation are numerically investigated by large eddy simulation (LES) turbulent model. The inlet velocities of both the main and branch pipes are assumed to be sinusoidal distribution, which is similar to the rolling condition in the ocean. Thermal mixing between hot and cold fluids with temperature differences of 15 K, 30 K and 45 K is carried out in the present study. The flow and mixing characteristics, including qualitative and quantitative analyses of temperature and velocity are studied. The results show that the reverse flow occurs in the unsteady thermal mixing processes due to the effect of inertia force, and the area of reverse flow decreases as the inlet temperature difference increases. Increasing inlet temperature difference induces a more stable thermal stratification flow with smaller thermal mixing length and lower temperature gradient. The maximum root mean square (RMS) of temperature fluctuation slightly decreases and shifts to the upper of main pipe as the inlet temperature difference increases. In addition, the spectral analysis of temperature fluctuation performed by Wavelet Transform (WT) indicates that the number of frequency peaks decreases as the temperature difference increases. Meanwhile, the main frequencies of wavelet power spectrum densities (WPSDs) for the lower points (points 1 ~ 3) decrease, while those for the upper points (points 5 ~ 7) increase as the temperature difference increases.

Phase change thermal storage technology has received considerable attention in the thermal management of electronic devices. Unfortunately, the efficiency using paraffin is too low to meet the heat dissipation requirements of high power devices. In this work, gallium is selected as the phase change material, and the melting mechanism of gallium heat sink in spatial distributions is examined by experiment. Results show that the heat transfer efficiency of regions in the Y-cross section near the heating surface and in the X-cross section near the upper surface of the gallium heat sink are better than other regions. The average effective thermal conductivity of the gallium heat sink reaches 71.97 W/(m·K). The natural convection promotes the overall melting rate, but it results in the inefficient heat transfer in the middle melting stage and worse heat transfer in the later melting stage. Compared with the copper foam/paraffin composite heat sink in the same size, the overall and most of melting time of the gallium heat sink is reduced by 55.5% and 56.0%, respectively. At the same thermal storage capacity, the volume and weight of the gallium heat sink are reduced by 67% and 18%, respectively, compared with the copper foam/paraffin composite heat sink.

Based on the potential energy surface reported by Yuan and co-workers (Phys. Chem. Chem. Phys. 17 (2015) 11732–11739), the specific state (v0 = 0, j0 = 0) dynamics calculations of the Li(2S) + H2(X1Σg+) → LiH(X1Σ+) + H(2S) reaction were performed using the time-dependent wave packet and quasi-classical trajectory methods in the collision energy range from 2.0 to 3.0 eV. The reaction probability, integral cross section, differential cross section, the distribution of LiH product and so on were reported at state-to-state level of theory. The results obtained by quasi-classical trajectory method are in good agreement with quantum values, which indicates that the quantum effect is not very apparent. The differential cross sections results indicate that the abstract reaction mechanism is dominant in the reaction.

Based on the potential energy surface reported by Li and co-workers (J. Comput. Chem. 34 1686–1696 (2013)), the dynamics calculations of N(2D) + H2(v0 = 0, j0 = 0) reaction and its isotopic variant...