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Genome resequencing uncovers genome-wide DNA polymorphisms that are useful for the development of high-density InDel markers between two barley cultivars. Discovering genomic variations and developing genetic markers are crucial for genetics studies and molecular breeding in cereal crops. Although InDels (insertions and deletions) have become popular because of their abundance and ease of detection, discovery of genome-wide DNA polymorphisms and development of InDel markers in barley have lagged behind other cereal crops such as rice, maize and wheat. In this study, we re-sequenced two barley cultivars, Golden Promise (GP, a classic British spring barley variety) and Hua30 (a Chinese spring barley variety), and mapped clean reads to the reference Morex genome, and identified in total 13,933,145 single nucleotide polymorphisms (SNPs) and 1,240,456 InDels for GP with Morex, 11,297,100 SNPs and 781,687 InDels for Hua30 with Morex, and 13,742,399 SNPs and 1,191,597 InDels for GP with Hua30. We further characterized distinct types, chromosomal distribution patterns, genome location, functional effect, and other features of these DNA polymorphisms. Additionally, we revealed the functional relevance of these identified SNPs/InDels regarding different flowering times between Hua30 and GP within 17 flowering time genes. Furthermore, we developed a series of InDel markers and validated them experimentally in 43 barley core accessions, respectively. Finally, we rebuilt population structure and phylogenetic tree of these 43 barley core accessions. Collectively, all of these genetic resources will facilitate not only the basic research but also applied research in barley.

Physical unclonable function (PUF) is a promising lightweight hardware security primitive for resource-limited Internet-of-Things (IoT) devices. Strong PUFs are suitable for lightweight device authentication because it can generate quantities of challenge-response pairs. Unfortunately, while the machine learning (ML) techniques have benefited various areas such as Internet, industrial automation, robotics and gaming, they pose a severe threat to PUFs by easily modelling their behaviour. This paper first shows that even a recently reported dual-mode PUF can be cloned by ML (prediction accuracy of up to 95%). To solve this issue, we propose a configurable tristate (CT) PUF which can flexibly perform as an arbiter PUF, a ring oscillator (RO) PUF, or a bistable ring (BR) PUF with a bitwise XOR-based mechanism to obfuscate the relationship between the challenge and the response, hence resisting the ML attacks. An authentication protocol for the use in IoT security is presented. The CT PUF is implemented on Xilinx ZedBoard FPGAs with placement and routing details described. The experimental results show that the modelling accuracy of logistic regression (LR), support vector machines (SVM), covariance matrix adaptation evolutionary strategies (CMA-ES), and artificial neural networks (ANN) is close to 60% (50% as the ideal number in theory) while meeting the PUF requirements for uniformity, reliability, and uniqueness. The hardware overhead and power consumption are slight. The entire project has been open-sourced.

It is a challenging task to deploy lightweight security protocols in resource-constrained IoT applications. A hardware-oriented lightweight authentication protocol based on device signature generated during voltage over-scaling (VOS) was recently proposed to address this issue. VOS-based authentication employs the computation unit such as adders to generate the process variation dependent error which is combined with secret keys to create a two-factor authentication protocol. In this paper, machine learning (ML)-based modeling attacks to break such authentication is presented. We also propose a \underline{c}hallenge \underline{s}elf-\underline{o}bfuscation \underline{s}tructure (CSoS) which employs previous challenges combined with keys or random numbers to obfuscate the current challenge for the VOS-based authentication to resist ML attacks. Experimental results show that ANN, RNN and CMA-ES can clone the challenge-response behavior of VOS-based authentication with up to 99.65% prediction accuracy, while the prediction accuracy is less than 51.2% after deploying our proposed ML resilient technique. In addition, our proposed CSoS also shows good obfuscation ability for strong PUFs. Experimental results show that the modeling accuracies are below 54% when $10^6$ challenge-response pairs (CRPs) are collected to model the CSoS-based Arbiter PUF with ML attacks such as LR, SVM, ANN, RNN and CMA-ES.

Temperature stresses affect plant phenotypic diversity. The developmental stability of the inflorescence, required for reproductive success, is tightly regulated by the interplay of genetic and environmental factors. However, the mechanisms underpinning how plant inflorescence architecture responds to temperature are largely unknown. We demonstrate that the barley SEPALLATA MADS-box protein HvMADS1 is responsible for maintaining an unbranched spike architecture at high temperatures, while the loss-of-function mutant forms a branched inflorescence-like structure. HvMADS1 exhibits increased binding to target promoters via A-tract CArG-box motifs, which change conformation with temperature. Target genes for high-temperature-dependent HvMADS1 activation are predominantly associated with inflorescence differentiation and phytohormone signalling. HvMADS1 directly regulates the cytokinin-degrading enzyme HvCKX3 to integrate temperature response and cytokinin homeostasis, which is required to repress meristem cell cycle/division. Our findings reveal a mechanism by which genetic factors direct plant thermomorphogenesis, extending the recognized role of plant MADS-box proteins in floral development.

Recently, the development of modern vehicles has brought about aggressive integration and miniaturization of on-board electrical and electronic devices. It will lead to exponential growth in both the overall waste heat and heat flux to be dissipated to maintain the devices within a safe temperature range. However, both the total heat sinks aboard and the cooling capacity of currently utilized thermal control strategy are severely limited, which threatens the lifetime of the on-board equipment and even the entire flight system and shrink the vehicle’s flight time and range. Facing these thermal challenges, the USA proposed the program of “INVENT” to maximize utilities of the available heat sinks and enhance the cooling ability of thermal control strategies. Following the efforts done by the USA researchers, scientists in China fought their ways to develop thermal management technologies for Chinese advanced energy-optimized airplanes and spacecraft. This paper elaborates the available on-board heat sinks and aerospace thermal management systems using both active and passive technologies not confined to the technology in China. Subsequently, active thermal management technologies in China including fuel thermal management system, environment control system, non-fuel liquid cooling strategy are reviewed. At last, space thermal control technologies used in Chinese Space Station and Chang’e-3 and to be used in Chang’e-5 are introduced. Key issues to be solved are also identified, which could facilitate the development of aerospace thermal control techniques across the world.

Strong physical unclonable function (PUF) is a promising solution for device authentication in resourceconstrained applications but vulnerable to machine learning attacks. In order to resist such attack, many defenses have been proposed in recent years. However, these defenses incur high hardware overhead, degenerate reliability and are inefficient against advanced machine learning attacks such as approximation attacks. In order to address these issues, we propose a Random Set-based Obfuscation (RSO) for Strong PUFs to resist machine learning attacks. The basic idea is that several stable responses are derived from the PUF itself and pre-stored as the set for obfuscation in the testing phase, and then a true random number generator is used to select any two keys to obfuscate challenges and responses with XOR operations. When the number of challenge-response pairs (CRPs) collected by the attacker exceeds the given threshold, the set will be updated immediately. In this way, machine learning attacks can be prevented with extremely low hardware overhead. Experimental results show that for a 64x64 Arbiter PUF, when the size of set is 32 and even if 1 million CRPs are collected by attackers, the prediction accuracies of Logistic regression, support vector machines, artificial neural network, convolutional neural network and covariance matrix adaptive evolutionary strategy are about 50% which is equivalent to the random guessing., 12 pages, 8 figures

At present, the development of electrochemiluminescence (ECL) immunosensor with excellent performance is still the research focus of immunoassay and detection. Herein, SnS

The liquid-liquid interface evolution characteristic during droplets coalescence in the surrounding liquid is numerically studied taking no account of the influence of the gravity. The influences of viscosity ratio of internal and external fluids as well as the relative size and Oh number of the droplets on the coalescence process are analyzed. The results show that, three coalescence types are indicated in this numerical study. With the decrease of viscosity ratio and Oh, the droplet coalescence type transforms from coalescence with no pinch-off to coalescence with pinch-off. As the radius radio of the larger and smaller droplets decreases, the coalescence type transforms from “coalescence with single pinch-off” to “coalescence with double pinch-offs” or “coalescence with no pinch-off”. The liquid bridge radius increases slower under the less viscosity ratio and larger Oh due to the greater viscous resistance during coalescence process. The dimensionless pinch-off time of the neck decreases with the increase of the viscosity ratio and radius radio, and the decrease of Oh. And when viscosity ratio is greater than 10 and Oh is less than 0.01, the dimensionless pinch-off time changes little.

In this paper, a free energy lattice Boltzmann model of vapor condensation on a surface with a wettability gradient is developed and numerically analyzed to understand the microscopic behaviors of self-propelled droplet condensation. The effect of wettability gradient on droplet self-motion and coalescence as well as vapor condensation is examined and investigated. The condensation rate is presented during the whole droplet condensation process to analyze the role of wettability gradient on droplet condensation. The results indicate that the surface with wettability gradient is preferred for vapor condensation owing to the appearance of self-propelled droplet condensation. Condensate film is initially spread on the high surface energy region, and liquid nucleation sites form, grow and, subsequently, coalesce with other droplets on low surface energy regions. The condensation rate is higher on a surface with a larger wettability gradient due to the more effective removal of condensate. In addition, the condensation rate fluctuates with time at the quasi-steady-state stage. During the condensation process, the droplet coalescence triggers a sudden peak of condensation rate, and the generation of new nucleation results in a rapid increase in the condensation rate.

Carpel is the ovule-bearing female reproductive organ of flowering plants and is required to ensure its protection, an efficient fertilization, and the development of diversified types of fruits, thereby it is a vital element of most food crops. The origin and morphological changes of the carpel are key to the evolution and adaption of angiosperms. Progresses have been made in elucidating the developmental mechanisms of carpel establishment in the model eudicot plantArabidopsis thaliana, while little and fragmentary information is known in grasses, a family that includes many important crops such as rice (Oryza sativa), maize (Zea mays), barley (Hordeum vulgare), and wheat (Triticum aestivum). Here, we highlight recent advances in understanding the mechanisms underlying potential pathways of carpel development in grasses, including carpel identity determination, morphogenesis, and floral meristem determinacy. The known role of transcription factors, hormones, and miRNAs during grass carpel formation is summarized and compared with the extensively studied eudicot model plantArabidopsis. The genetic and molecular aspects of carpel development that are conserved or diverged between grasses and eudicots are therefore discussed.

Central Processing Unit (CPU) is considered as the brain of a computer. If the CPU has vulnerabilities, the security of software running on it is difficult to be guaranteed. In recent years, various micro-architectural cache side-channel attacks on the CPU such as Spectre and Meltdown have appeared. They exploit contention on internal components of the processor to leak secret information between processes. This newly evolving research area has aroused significant interest due to the broad application range and harmfulness of these attacks. This article reviews recent research progress on micro-architectural cache side-channel attacks and defenses. First, the various micro-architectural cache side-channel attacks are classified and discussed. Then, the corresponding countermeasures are summarized. Finally, the limitations and future development trends are prospected.

The theoretical model of the evaporation and condensation heat transfer process of the axially grooved heat pipe (AGHP) assisted by gravity under small angle inclination is established to investigate the evaporation regimes and the heat transfer characteristics of AGHP. To reveal the heat transfer mechanism of the AGHP, the working state and gas-liquid interface distribution of the AGHP with different input power are analysed. And the influence of the inclination angle and groove structure (length-width ratio), including on the maximum heat transfer of AGHP is also discussed. The numerical simulations indicate that: With the increasing input power, the fin-film evaporation regime transits to the corner-film evaporation regime in the AGHP. The growing inclination angle enhances the gravitational effect on the liquid reflux and increases the critical input power for the evaporation regime transition. As the aspect ratio of the grooves increase, the increasing maximum radius of the meniscus leads to stronger heat transfer capacity of the AGHP.

Temperature stresses affect plant phenotypic diversity. The developmental stability of the inflorescence, required for reproductive success, is tightly regulated by the interplay of genetic and environmental factors. However, the mechanisms underpinning how plant inflorescence architecture responds to temperature are largely unknown. We demonstrate that the barley SEPALLATA MADS-box protein HvMADS1 is responsible for maintaining an unbranched spike architecture at high temperatures, while the loss-of-function mutant forms a branched inflorescence-like structure. HvMADS1 exhibits increased binding to target promoters via A-tract CArG-box motifs, which change conformation with temperature. Target genes for high-temperature-dependent HvMADS1 activation are predominantly associated with inflorescence differentiation and phytohormone signalling. HvMADS1 directly regulates the cytokinin-degrading enzyme HvCKX3 to integrate temperature response and cytokinin homeostasis, which is required to repress meristem cell cycle/division. Our findings reveal a mechanism by which genetic factors direct plant thermomorphogenesis, extending the recognized role of plant MADS-box proteins in floral development.

The GRAS (named after first three identified proteins within this family, GAI, RGA, and SCR) family contains plant-specific genes encoding transcriptional regulators that play a key role in gibberellin (GA) signaling, which regulates plant growth and development. Even though GRAS genes have been characterized in some plant species, little research is known about the GRAS genes in barley (Hordeum vulgare L.). In this study, we observed 62 GRAS members from barley genome, which were grouped into 12 subgroups by using phylogenomic analysis together with the GRAS genes from Arabidopsis (Arabidopsis thaliana), maize (Zea mays), and rice (Oryza sativa). Chromosome localization and gene structure analysis suggested that duplication events and abundant presence of intronless genes might account for the massive expansion of GRAS gene family in barley. The analysis of RNA-seq data indicates the expression pattern of GRAS genes in various tissues at different stages in barley. Noteworthy, our qRT-PCR analysis showed the expression of 18 candidate GRAS genes abundantly in the developing inflorescence, indicating their potential roles in the barley inflorescence development and reproduction. Collectively, our evolutionary and expression analysis of GRAS family are useful for future functional characterization of GA signaling in barley and agricultural improvement.

The theoretical model of the heat transfer in the photovoltaic thermal (PV/T) collector with different parallel cooling channels is established to evaluate the effect of parallel cooling channels on the thermal performance of the PV/T collector. To design the structure of the parallel cooling channels, the influences of structural paremeters are discussed. The numerical results indicate that with the number of the subchannels of 10, the pressure drop of the cooling channels is the lowest. Meanwhile, the temperatures of the photovoltaic modules are low and evenly distributed. Moreover, the I-type configuration of the inlet and outlet is the best choice, since the pressure drop of the cooling channels is low and the thermal performance of the PV/T collector is excellent. With the increasing diameter ratio between the main channel and the subchannels, the temperature of the photovoltaic modules is decreasing and the more evenly distributed. Moreover, the figure of merit of the cooling channels with D/d = 4 could be 50% larger than that with D/d = 2.

We experimentally investigate the coalescence between two droplets with different sizes in the surrounding water via high-speed visualization. We identify three coalescence patterns by clarifying the dynamic interface evolutions, including liquid bridge evolution, capillary wave propagation, and pinch-off behaviours. The results indicate that the coalescence patterns are directly related to the propagation of capillary waves on the coalescent droplet, which is governed by the competition among the capillary force, viscous force, and inertia involved in the draining from the original droplets into the liquid bridge. The external water can efficiently damp the oscillation in capillary wave propagation after the coalescence. In the inertial regime after the droplet coalescence, the evolution of liquid bridge is observed to follow a linear scaling law, when the capillary force induced by the azimuthal interface of the liquid bridge drives the liquid bridge expansion. Accordingly, a phase diagram is organized to characterize these coalescence patterns depending on Ohnesorge number, relative viscosity between external water and droplet, and size ratio between two coalesced droplets. This article is protected by copyright. All rights reserved

A model of vapor condensation on a solid surface is developed and numerically analyzed using the free-energy lattice Boltzmann method. Based on the model, the condensation phase change on hydrophobic, hydrophilic and gradient surfaces are simulated with a particular focus on the condensation on a gradient surface. The droplet nucleation, growth, deformation, coalescence and motion during the condensation on a gradient surface are investigated. The present simulation reproduces the self-propelled dropwise condensation on a gradient surface, the film condensation on a hydrophilic surface and the conventional dropwise condensation on a hydrophobic surface. The results indicate that the condensed droplets on a gradient surface can be swept in time to provide a favorable condition for the subsequent condensation. On a smooth gradient surface, owing to the unbalanced wetting force, the vapor condenses into a thin film firstly and then fractures into droplet nucleation as the condensation process goes on. The larger wettability gradient results in a larger amplitude oscillation of condensation rate and a slighter variation of surface coverage.

The condensation flow patterns of ethanol–water mixture in a wide range of ethanol mass concentration inside a hydrophobic microchannel is experimentally studied via a high speed imaging system. The effects of channel surface wettability and ethanol concentration on flow condensation are compared and discussed. The experimental results indicate that the surface hydrophobic modification and ethanol concentration play a significant role in the flow condensation of mixture in a microchannel. The droplet condensation appears almost the whole two-phase flow region when the water steam is the main component, in which the droplet flow, droplet-streak flow, droplet-annular flow, droplet-injection flow and droplet-slug/bubble flow occur sequentially in a hydrophobic microchannel. With increasing ethanol concentration, the droplet-slug/bubble flow after droplet-injection flow disappears and is replaced by the pure slug/bubble flow. When the ethanol vapor is the main component, the droplet condensation almost disappears, and the annular-streak flow, annular flow, injection flow and slug/bubble flow appear sequentially along the flow direction. Both an increase in vapor Reynolds number and a decrease in ethanol concentration cause the injection location move toward the channel outlet. In addition, the surface hydrophobic modification introduces the droplet condensation, which is beneficial for the flow condensation heat transfer.

A theoretical model of the coupled boiling and condensation phase changer heat transfer in a confined chamber is developed and numerically analyzed based on the modified hybrid lattice Boltzmann method. The interaction of boiling and condensation behavior is investigated with particular attention focused on the influence of condensation surface wettability on the boiling heat transfer process. Besides, the temperature response and the detailed two-phase flow pattern inside the chamber with different condensation surface wettability are evaluated. The results indicated that an optimal contact angle of 85° for the condensation surface wettability promoted the heat transfer on the evaporation surface. Subsequently, two modified condensation surfaces (biphilic surface with alternative hydrophilic and hydrophobic regions and gradient surface with a gradual wettability transition from hydrophilic to hydrophobic) are proposed for further heat transfer enhancement of the confined chamber. The results of the boiling curves, the two-phase flow pattern and the local/averaged heat transfer coefficient on the evaporation surface indicated that, compared with the single wettability with the optimal contact angle, both modified condensation surfaces can achieve a higher critical heat flux and a higher boiling heat transfer coefficient. Among these, the biphilic surface can achieve relatively better heat transfer performance.

This paper reports the use of a phase change material (PCM)/fractal metal matrices composite as an innovative solution for melting intensification in horizontal latent heat storage (LHS) systems. The mathematical model of melting heat transfer in the LHS systems containing pure PCM and PCM composite is presented and numerically simulated. The effects of the heat transfer fluid (HTF) temperature and metal material on charging performance are examined quantitatively. Moreover, the distribution optimization of metal matrices for the improvement of melting performance is accomplished using the response surface method (RSM) technique. The results indicate that the presence of metal matrices enhances the heat transfer rate and temperature uniformity of LHS systems. Compared with pure PCM, the duration time of complete melting and solidification for the innovative PCM composites with the same volume is shortened by 93.9% and 95.9%, respectively. The melting process is initially dominated by heat conduction, followed by free convection, while the role of heat convection diminishes as the final melting process proceeds. Given the trade-offs between performance and cost, red copper is preferred for applications focusing on thermal performance, while aluminium alloy is a better choice for large-scale applications in practical engineering. The optimal distribution parameters for metal matrices are: length ratio α = 0.28, fractal level n = 2, and thickness exponent Δ = 0.58.

A three-dimensional unsteady theoretical model of droplet spreading process on an inclined surface is developed and numerically analyzed to investigate the droplet spreading dynamics via the lattice Boltzmann simulation. The contact line motion and morphology evolution for the droplet spreading on an inclined surface, which are, respectively, represented by the advancing/receding spreading factor and droplet wetted length, are evaluated and analyzed. The effects of surface wettability and inclination on the droplet spreading behaviors are examined. The results indicate that, dominated by gravity and capillarity, the droplet experiences a complex asymmetric deformation and sliding motion after the droplet comes into contact with the inclined surfaces. The droplet firstly deforms near the solid surface and mainly exhibits a radial expansion flow in the start-up stage. An evident sliding-down motion along the inclination is observed in the middle stage. And the surface-tension-driven retraction occurs during the retract stage. Increases in inclination angle and equilibrium contact angle lead to a faster droplet motion and a smaller wetted area. In addition, increases in equilibrium contact angle lead to a shorter duration time of the middle stage and an earlier entry into the retract stage.

The role of atmospheric pressure on the frost formation process including the droplet growth, freezing process and frost growth process on the cold surface under natural convection condition is investigated experimentally via a visualization system. The visualization system, configured with the enclosed tank, observation window, microscopy setup and vacuum unit, is used to observe the frost formation process on the cold surface in low atmospheric pressure. The results indicate that the atmospheric pressure plays a significant role in the whole frost formation process. Decreases in atmospheric pressure lead to a smaller phase transition driving force and hence results in a longer time for the process of droplet growth and freezing. The frost crystal shape transforms from irregular to a columnar type and then to a dendritic type when the atmospheric pressure increases from 0.1 bar to 0.5 bar and then to 1 bar. In particular, the frost layer turns to be thinner and sparser in a lower atmospheric pressure.

By the combination of high-speed imaging and numerical simulation, we explore the hydrodynamics and possible morphologies of the entire coalescence of a pendent droplet and sessile one. We identify three types of coalescence morphologies and plot a corresponding phase diagram to identify them depending on the Bond number and the size ratio between the two droplets. In addition to the well-known linear inertial growth of the liquid bridge at the initial contact of the two drops, we observe a new subsequent slower linear expansion of the liquid bridge and provide a linear scaling law with a measured prefactor to quantitatively represent it. This new growth is found to be due to the transition of the capillary force produced by a change in the azimuthal surface profile of the liquid bridge.

A molecular dynamics simulation is performed to study the liquid film evaporation on rough surfaces constructed by the Cantor set fractal. The liquid film evaporation on the rough surfaces with different roughness and fractal dimensions is presented and is compared with that on smooth surface. The results indicate that the response speed for evaporation on the rough surface is faster than that on the smooth surface and is accelerated with the increase of the roughness height and the fractal dimensions. Protrusions on the rough surface are conducive to heat transfer enhancement, and thus, the evaporation on a rough surface can reach equilibrium earlier than that on a smooth surface. With increasing roughness and fractal dimension, the evaporation rate and the thickness of the non-evaporating liquid layer increase.

A theoretical model of liquid flow through porous media is developed and numerically analyzed to investigate the role of pore structure on liquid flow behaviors in porous media. In this model, the Siepinski fractal is utilized to construct the geometry structure of porous media. The velocity distribution in fractal porous media is evaluated and analyzed, and the effects of porosity and pore structure on permeability are examined. The results indicate that the pore structure plays a significant role on determining the flow and transport properties in porous media. The liquid through the interconnected network of channels is unevenly distributed, the streamline is no longer straight inside inter-connected channels, and the swirl patterns occur in the rear of solid matrix. Induced by complex pore structure coupled with liquid–solid interaction, the permeability of porous media may deviate from the monotonous decrease trend with increasing specific surface for a given porosity. In addition, the pore distribution and connectivity also affect the permeability of porous media flow even though at the same porosity and fractal dimension. Interestingly, the presence of large long straight gap may be the dominating factor to enhance permeability for porous media flow.