Search

Neocentromeres develop when kinetochores assemble de novo at DNA loci that are not previously associated with CenH3 nucleosomes, and can rescue rearranged chromosomes that have lost a functional centromere. The molecular mechanisms associated with neocentromere formation in plants have been elusive. Here, we developed a Xian (indica) rice line with poor growth performance in the field due to approximately 272 kb deletion that spans centromeric DNA sequences, including the centromeric satellite repeat CentO, in the centromere of chromosome 8 (Cen8). The CENH3-binding domains were expanded downstream of the original CentO position in Cen8, which revealed a de novo centromere formation in rice. The neocentromere formation avoids chromosomal regions containing functional genes. Meanwhile, canonical histone H3 was replaced by CENH3 in the regions with low CENH3 levels, and the CenH3 nucleosomes in these regions became more periodic. In addition, we identified active genes in the deleted centromeric region, which are essential for chloroplast growth and development. In summary, our results provide valuable insights into neocentromere formation and show that functional genes exist in the centromeric regions of plant chromosomes.

Three-dimensional (3D) chromatin organization is highly dynamic during development and seems to play a crucial role in regulating gene expression. Self-interacting domains, commonly called topologically associating domains (TADs) or compartment domains (CDs), have been proposed as the basic structural units of chromatin organization. Surprisingly, although these units have been found in several plant species, they escaped detection in Arabidopsis (Arabidopsis thaliana). Here, we show that the Arabidopsis genome is partitioned into contiguous CDs with different epigenetic features, which are required to maintain appropriate intra-CD and long-range interactions. Consistent with this notion, the histone-modifying Polycomb group machinery is involved in 3D chromatin organization. Yet, while it is clear that Polycomb repressive complex 2 (PRC2)-mediated trimethylation of histone H3 on lysine 27 (H3K27me3) helps establish local and long-range chromatin interactions in plants, the implications of PRC1-mediated histone H2A monoubiquitination on lysine 121 (H2AK121ub) are unclear. We found that PRC1, together with PRC2, maintains intra-CD interactions, but it also hinders the formation of H3K4me3-enriched local chromatin loops when acting independently of PRC2. Moreover, the loss of PRC1 or PRC2 activity differentially affects long-range chromatin interactions, and these 3D changes differentially affect gene expression. Our results suggest that H2AK121ub helps prevent the formation of transposable element/H3K27me1-rich long loops and serves as a docking point for H3K27me3 incorporation.

A serendipitous and efficient approach to access various δ-carbolines was developed through base-promoted cascade β-F-elimination/electrocyclization/Diels–Alder/retro-Diels–Alder reaction in good to high yields with excellent regio/chemoselectivity.

Kongzhuang coal mine of Shanghai Datun Energy Resources Co., Ltd. is a typical deep coal mine in eastern China. The mining disturbance of working face in deep coal mine leads to the fracture and movement of overlying strata and the damage of the aquifer in overlying strata, thereby causing water inrush disaster and posing a serious threat to the safety production in coal mine. Therefore, the temporal and spatial evolution mechanism of the water-conducting fractured zone of overlying strata in the Kongzhuang coal mine is researched systematically in this paper. Especially, the hydro-geological conditions and mining conditions in the Kongzhuang coal mine are analyzed; on this basis, the fracture and movement of overlying strata are simulated by physical similarity simulation test, and the temporal and spatial evolution rule of overlying strata in the Kongzhuang coal mine is obtained. Besides, the development height of “two zones” is measured by double-end water shutoff detection method, and the risk assessment for the water inrush disaster of the coal seam roof is carried out in the Kongzhuang coal mine. The research achievements in this paper indicate that the water-conducting channel formed in the mining process of #7 coal seam is the most important water-filling channel. Quaternary aquifer water recharges the mine indirectly through the bedrock aquifer, and the sandy mudstone with large thickness is the key layer to control the development of a water-conducting fracture zone. Meanwhile, the height of the caving zone is 26.7 m, about 8.3 times of mining height, and the height of the fracture zone is 68.3 m, approximately equal to 16.26 of the mining height. The results of #1 and #2 borehole leakages in the double-end water shutoff detection method show that the height of the water-conducting fractured zone is 63.70 m-65.27 m, and the split-to-mining ratio is 15.17-15.54. The water inrush risk of the coal seam roof shows that most of the 7436 working face is in the transition zone, and a small area around the cutting hole of the working face is in the relatively dangerous zone. Therefore, the innovation of this paper is that the temporal and spatial evolution mechanism of the water-conducting fractured zone of overlying strata in the Kongzhuang coal mine is revealed, which provides the theoretical guidance for the prediction and prevention of water inrush disaster in the coal mine with the similar mining conditions.

Among the various scanning techniques, spot and raster scanning are the most frequently adopted. Raster scanning turns off the beam only when each isoenergy slice irradiation is completed. This feature intrinsically solves the leakage dose and frequent beam-switching problems encountered during spot scanning. However, to shorten the delivery time of raster scanning, a sophisticated dose control strategy is required to guarantee dose distribution. In this study, a real-time compensation method with raster scanning for synchrotron systems was designed. It is characterized by a small spot-spacing planning strategy and real-time subtraction of the transient number of particles delivered between two planning-spot positions from the planned number of particles of the subsequent raster point. The efficacy of the compensation method was demonstrated by performing accurate raster scanning simulations with an in-house simulation code and accurate final dose evaluations with a commercial treatment planning system. Given the similar dose evaluation criteria under a practical high scanning speed, compared with the spot scanning method, the total delivery time of the compensated raster scanning method was significantly shortened by 53.3% in the case of irradiating a cubical target and by 28.8% in a pelvic case. Therefore, it can be concluded that real-time compensated raster scanning with a fast scanning configuration can significantly shorten the delivery time compared to that of spot scanning. It is important to reduce the pressure on patients caused by prolonged immobilization and to improve patient throughput capacity at particle therapy centers.

Thin-film architectures are a staple in a wide range of technologies, such as semiconductor devices, optical coatings, magnetic recording, solar cells and batteries. Despite the industrial success of thin-film technology, mostly due to the easy fabrication and low cost, a fundamental drawback remains: it is challenging to alter the features of the film once fabricated. Here we report a methodology to modify the thickness and sequence of the innermost solid-state thin-film layers. We start with a thin-film stack of amorphous iron oxide and silver. By applying a suitable voltage bias and then reversing it, we can float the silver layer above or below the oxide layer by virtue of the migration of silver atoms. Scanning transmission electron microscopy reveals various sequences and thicknesses of the silver and oxide layers achieved with different experimental conditions. As a proof-of-principle, we show a dynamic change of structural colours of the stack derived from this process. Our results may offer opportunities to dynamically reconfigure thin-film-based functional nanodevices in situ.

Structured interfaces with subwavelength features enable modulations of phase, amplitude, and polarization on demand, leading to a plethora of flat-profile devices and metasurfaces. Plasmonic and dielectric metasurfaces have been intensively explored, building up the frameworks of flat optics for ultrathin and integrated nanophotonics. The in situ controllability and tunability of aforementioned family of metasurfaces, however, has been a grand challenge, due to the intrinsic limitations of the materials. Semiconductors with diversified catalogs of material candidates thus demonstrate promising potentials, owing to the mature and versatile technologies developed nowadays. The fuse of semiconductors and nanostructured metasurfaces has been witnessed more recently, paving a distinct avenue toward active, tunable, reconfigurable light manipulation for next-generation optical nanodevices. Judicious selection of the active materials for metasurfaces empowers the active functionality of the designer applications. This paper presents a review of this merging semiconductor paradigm for active metasurfaces across a wide range of spectrum and shows unprecedented potentials in the future interface-based optoelectronics, quantum optics, nano-optics, and surface engineering with full compatibility of semiconductor foundry.

Metasurfaces are engineered surfaces that consist of subwavelength periodic elements and can be used to manipulate electromagnetic waves. Multifunctional or reconfigurable electromagnetic meta-devices based on a direct-current biasing system can be built using lumped electronic components. However, such meta-devices require bulky power supplies, field-programmable gate arrays, electrical wires and complex control circuits. Here, we report a digital metasurface platform that can be programmed optically to implement electromagnetic functions. Our digital platform has 6 × 6 subarrays, each of which contains 4 × 4 metasurface elements based on electronic varactors integrated with an optical interrogation network based on photodiodes. The interrogation network can convert visible light illumination patterns to voltages and applies bias to the metasurface elements, generating specific microwave reflection phase distributions. To illustrate the capabilities of our approach, we use the optically driven digital metasurface for external cloaking, illusion and dynamic vortex beam generation. A digital platform that integrates a metasurface based on electronic varactors with an optical interrogation network based on photodiodes can be programmed by visible light to implement electromagnetic functions, including microwave cloaking, illusion and vortex beam generation.

Nowadays, complicated preparation processes and harsh sintering conditions wave transparent ceramics limit its further development. To solve this problem, we explore a promising precursor by adopting a polymerization-pyrolysis method to prepare porous Si–Al–O–B ceramics at a mild sintering condition (1000 °C). The porous Si–Al–O–B ceramics exhibits enhanced wave transparency at 10–16 GHz with a low dielectric constant (

In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and e-amino acid derivatives.

An unprecedented Ir-catalyzed asymmetric cascade umpolung allylation/2-aza-Cope rearrangement of trifluoroethylisatin ketimines has been realized. The current method provides a facile access to biologically important α-trifluoromethyl-containing homoallylic amines in high yields with excellent enantioselectivity. Notably, umpolung reactivity of trifluoroethylisatin ketimine was discovered for the first time. Mechanism studies revealed the key intermediates in the initial umpolung allylation and the stereospecific chirality transfer in the subsequent 2-aza-Cope rearrangement.

The first example of highly efficient kinetic resolution of exo-3-oxodicyclopentadienes and endo-3-oxodicyclopentadiene has been developed by means of Cu(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide. Compared with the existing methodologies for those synthetically important optically active convex molecules, the current protocol provides an alternative but more practical approach from the readily available racemic starting materials, which is free from the repetitive reduction/oxidation steps in the enzymatic resolution or the indispensable stoichiometric amount of chirality-induction reagents.

Two Gram-negative, aerobic, motile bacteria strains were isolated from leaf spot disease of Quercus mongolica. Strain hsmgli-8T has 99.86 % 16S rRNA gene sequence similarity to LY10J, and the highest 16S rRNA gene sequence similarity to Pseudomonas cerasi 58T (97.2 %), then Pseudomonas ficuserectae JCM 2400T (97.18 %), Pseudomonas meliae CFBP 3225T, Pseudomonas tremae CFBP 6111T and Pseudomonas congelans DSM 14939T (all 97.12 %), and less than 97.1 % similarity to other recognized species. In phylogenetic trees based on 16S rRNA gene and multilocus sequence data, the two novel strains form a separate branch, indicating that they do not belong to any Pseudomonas group and subgroup, and should belong to a novel species within the genus Pseudomonas . This assertion is also supported by the results of genome average nucleotide identity analysis. The major fatty acids are C16 : 0, C18 : 1 ω7c and/or C18 : 1 ω6c, C16 : 1 ω7c and/or C16 : 1 ω6c. Polar lipids include phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, aminolipid and seven uncharacterized phospholipids. The predominant respiratory quinone is Q-9. The DNA G+C content is 59.45–59.50 mol%. Based on these data, we propose that the two novel strains should be assigned as a novel species within the genus Pseudomonas . We propose that the novel strains be named Pseudomonas quercus sp. nov. The type strain is hsmgli-8T (=CFCC 15739T=LMG 31544T).

Two Gram-negative, facultative anaerobic strains are isolated from the symptomatic tissue of willow bark canker. The cells grow at 4–41 ℃, pH 5.0–10.0, with optimal growth occuring at 30 °C and pH 7.0. Two novel strains share the highest 16S rRNA gene sequence similarity with Brenneria nigrifluens LMG 2694T (98.8%). In the phylogenetic trees based on sequences of 16S rRNA gene and four housekeeping genes (gyrB, rpoB, atpD and infB), two novel strains form a distinct branch from Brenneria species, indicating that two novel strains should belong to a novel species in the genus Brenneria, which is confirmed by the results of average nucleotide identity analysis and Digital DNA–DNA hybridization. Two novel strains have 81.9–85.0 % average nucleotide identity values with its closely relatives, B. nigrifluens LMG 2694T, B. alni DSM 11811T, B.corticis CFCC11842T, B. populi CFCC 11963T and B. corticis gBX10-1-2T, respectively, lower than the proposed species boundary cut-off for ANI (95-96 %). The main fatty acids are C16:0, C16:1 ω7c and C18:1 ω7c. The DNA G+C content is 53.5 -53.7 %. Based on these data, two novel strains represent a novel species within the genus Brenneria. The name Brenneria yuansilingia sp. nov. is proposed. The type strain is hezel4-2-4T (=CFCC 15597T = LMG 31719T).

Osteoarthritis (OA) is a joint disorder involving cartilage degeneration and subchondral bone sclerosis. The bone-cartilage interface is implicated in OA pathogenesis due to its susceptibility to mechanical and biological factors. The crosstalk between cartilage and the underlying subchondral bone is elevated in OA due to multiple factors, such as increased vascularization, porosity, microcracks and fissures. Changes in the osteochondral joint are traceable to alterations in chondrocytes and bone cells (osteoblasts, osteocytes and osteoclasts). The phenotypes of these cells can change with the progression of OA. Aberrant intercellular communications among bone cell-bone cell and bone cell-chondrocyte are of great importance and might be the factors promoting OA development. An appreciation of cellular phenotypic changes in OA and the mechanisms by which these cells communicate would be expected to lead to the development of targeted drugs with fewer side effects.

Thin-film architectures are a staple in a wide range of technologies, such as semiconductor devices, optical coatings, magnetic recording, solar cells and batteries. Despite the industrial success of thin-film technology, mostly due to the easy fabrication and low cost, a fundamental drawback remains: it is challenging to alter the features of the film once fabricated. Here we report a methodology to modify the thickness and sequence of the innermost solid-state thin-film layers. We start with a thin-film stack of amorphous iron oxide and silver. By applying a suitable voltage bias and then reversing it, we can float the silver layer above or below the oxide layer by virtue of the migration of silver atoms. Scanning transmission electron microscopy reveals various sequences and thicknesses of the silver and oxide layers achieved with different experimental conditions. As a proof-of-principle, we show a dynamic change of structural colours of the stack derived from this process. Our results may offer opportunities to dynamically reconfigure thin-film-based functional nanodevices in situ.

Geometric metasurfaces primarily follow the physical mechanism of Pancharatnam–Berry (PB) phases, empowering wavefront control of cross‐polarized reflective/transmissive light components. However, inherently accompanying the cross‐polarized components, the copolarized output components have not been attempted in parallel in existing works. Here, a general method is proposed to construct phase‐modulated metasurfaces for implementing functionalities separately in co‐ and cross‐polarized output fields under circularly polarized (CP) incidence, which is impossible to achieve with solely a geometric phase. By introducing a propagation phase as an additional degree of freedom, the electromagnetic (EM) energy carried by co‐ and cross‐polarized transmitted fields can be fully phase‐modulated with independent wavefronts. Under one CP incidence, a metasurface for separate functionalities with controllable energy repartition is verified by simulations and proof‐of‐principle microwave experiments. A variety of applications can be readily expected in spin‐selective optics, spin‐Hall metasurfaces, and multitasked metasurfaces operating in both reflective and transmissive modes., A general scheme based on a phase‐modulated metasurface for simultaneous and independent manipulation of co‐ and cross‐polarized wavefronts is proposed, which breaks through the inherent limitation of the geometric phase principle and achieves full energy modulation in output fields. The energy proportion between two orthogonal CP output functionalities can also be artificially manipulated as an extra freedom of degree for light manipulation.

Facile access to quaternary α-trifluoromethyl α-amino acids has been developed. This sequential reaction involves an Ir-catalyzed asymmetric allylation of α-trifluoromethyl aldimine esters followed by an unprecedented kinetic resolution.

The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality, holographic imaging, and nonlinear wavefront control. Transition-metal dichalcogenide (TMDC) monolayers offer giant optical nonlinearity within a few-angstrom thickness, but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light sources. In contrast, noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control, with hundred-nanometer pixel-level resolution; however, they suffer from intrinsically weak nonlinear susceptibility. Here, we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves, yielding drastically different nonlinear functionalities that cannot be accessed by either constituent. Such a hybrid nonlinear interface allows second-harmonic (SH) orbital angular momentum (OAM) generation, beam steering, versatile polarization control, and holograms, with an effective SH nonlinearity χ 2 of ~25 nm/V. This designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement, paving the way toward multifunctional and ultracompact nonlinear optical devices.

Background: Osteoarthritis (OA) is a joint disease that leads to a high disability rate and a low quality of life. With the development of modern molecular biology techniques, some key genes and diagnostic markers have been reported. However, the etiology and pathogenesis of OA are still unknown. Objective: To develop a gene signature in OA. Method: In this study, five microarray data sets were integrated to conduct a comprehensive network and pathway analysis of the biological functions of OA related genes, which can provide valuable information and further explore the etiology and pathogenesis of OA. Results and Discussion: Differential expression analysis identified 180 genes with significantly expressed expression in OA. Functional enrichment analysis showed that the up-regulated genes were associated with rheumatoid arthritis (p < 0.01). Down-regulated genes regulate the biological processes of negative regulation of kinase activity and some signaling pathways such as MAPK signaling pathway (p < 0.001) and IL-17 signaling pathway (p < 0.001). In addition, the OA specific protein-protein interaction (PPI) network was constructed based on the differentially expressed genes. The analysis of network topological attributes showed that differentially upregulated VEGFA, MYC, ATF3 and JUN genes were hub genes of the network, which may influence the occurrence and development of OA through regulating cell cycle or apoptosis, and were potential biomarkers of OA. Finally, the support vector machine (SVM) method was used to establish the diagnosis model of OA, which not only had excellent predictive power in internal and external data sets (AUC > 0.9), but also had high predictive performance in different chip platforms (AUC > 0.9) and also had effective ability in blood samples (AUC > 0.8). Conclusion: The 4-genes diagnostic model may be of great help to the early diagnosis and prediction of OA.

Recently, color generation in resonant nanostructures have been intensively studied. Despite of their exciting progresses, the structural colors are usually generated by the plasmonic resonances of metallic nanoparticles. Due to the inherent plasmon damping, such plasmonic nanostructures are usually hard to create very distinct color impressions. Here we utilize the concept of metasurfaces to produce all-dielectric, low-loss, and high-resolution structural colors. We have fabricated TiO2 metasurfaces with electron-beam lithography and a very simple lift-off process. The optical characterizations showed that the TiO2 metasurfaces with different unit sizes could generate high reflection peaks at designed wavelengths. The maximal reflectance was as high as 64% with full width at half-maximum (fwhm) around 30 nm. Consequently, distinct colors have been observed in bright field and the generated colors covered the entire visible spectral range. The detailed numerical analysis shows that the distinct colors wer...

It has been a long-term dream to achieve nanolaser array with uniform laser wavelengths, high densities, and high output powers. However, such kind of nanolaser array is practically quite challenging due to the variations of both bottom-up synthesized nanostructures and top-down etched devices. Herein we explore a simple method to achieve such kind of uniform nanolaser array. By placing a single crystalline CH3NH3PbBr3 nanoribbon onto a gold grating, both of our numerical calculation and experimental results show that the light can be well trapped by a waveguide mode around the air slot area, providing the possibility of high power nanolaser in a narrow air slot. The smallest size of the gap for light confinement is optimized to around 350–400 nm. Consequently, a high-density, uniform nanolaser array has been experimentally realized. And the coupling between different subunits is found to be negligibly small. We believe that this research can boost the progresses of nanolaser array and the corresponding p...

In this paper, an optimal selection method of gyroscope groups based on dedicated observer scheme and extended Kalman filter is proposed. According to the measurements of star sensors and gyroscopes, an extended Kalman filter is designed by the satellite attitude kinematic equation to estimate the attitude and generate the system residual. In addition, multiple sets of filters are built based on the redundancy of the gyroscope hardware. Three heads with the smallest error are selected to calculate the angular velocity of the satellite, achieving high-precision attitude determination. Simulation results verify the effectiveness of the proposed method.

The colour gamut, a two-dimensional (2D) colour space primarily comprising hue and saturation (HS), lays the most important foundation for the colour display and printing industries. Recently, the metasurface has been considered a promising paradigm for nanoprinting and holographic imaging, demonstrating a subwavelength image resolution, a flat profile, high durability, and multi-functionalities. Much effort has been devoted to broaden the 2D HS plane, also known as the CIE map. However, the brightness (B), as the carrier of chiaroscuro information, has long been neglected in metasurface-based nanoprinting or holograms due to the challenge in realising arbitrary and simultaneous control of full-colour HSB tuning in a passive device. Here, we report a dielectric metasurface made of crystal silicon nanoblocks, which achieves not only tailorable coverage of the primary colours red, green and blue (RGB) but also intensity control of the individual colours. The colour gamut is hence extruded from the 2D CIE to a complete 3D HSB space. Moreover, thanks to the independent control of the RGB intensity and phase, we further show that a single-layer silicon metasurface could simultaneously exhibit arbitrary HSB colour nanoprinting and a full-colour hologram image. Our findings open up possibilities for high-resolution and high-fidelity optical security devices as well as advanced cryptographic approaches., Synchronous Nanoprinting-Hologram Metasurfaces: Towards full hue-saturation-brightness control Structural colours with hue-saturation-brightness (HSB) control and independent integration with full-colour hologram open up possibilities for optical security devices and advanced cryptographic approaches. Researchers from China and Singapore propose a crystalline-silicon nanoblock metasurface that is able to control the intensity and phase of transmitted red, green, blue (RGB) lights independently. By mixing the three RGB nanoblocks with different intensity proportions together, it is possible to control the HSB value of the transmitted light, pushing the metasurface structural colour from conventional two-dimensional hue-saturation space to a real three-dimensional HSB space. Furthermore, arbitrary HSB colour printing and full-colour hologram images can be integrated in one single metasurface structure. That makes a drastic leap for singlet multifunctional metasurfaces, instead of cascading multiple metasurfaces with one for colourprinting and the other for hologram respectively.

Fluorescence in situ hybridization using probes based on oligonucleotides (oligo-FISH) is a useful tool for chromosome identification and karyotype analysis. Here we developed two oligo-FISH probes that allow the identification of each of the 12 pairs of chromosomes in rice (Oryza sativa). These two probes comprised 25 717 (green) and 25 215 (red) oligos (45 nucleotides), respectively, and generated 26 distinct FISH signals that can be used as a barcode to uniquely label each of the 12 pairs of rice chromosomes. Standard karyotypes of rice were established using this system on both mitotic and meiotic chromosomes. Moreover, dual-color oligo-FISH was used to characterize diverse chromosomal abnormalities. Oligo-FISH analyses using these probes in various wild Oryza species revealed that chromosomes from the AA, BB or CC genomes generated specific and intense signals similar to those in rice, while chromosomes with the EE genome generated less specific signals and the FF genome gave no signal. Together, the oligo-FISH probes we established will be a powerful tool for studying chromosome variations and evolution in the genus Oryza.

In this paper, we study fatigue failure using the variational multiscale method (VMM). In the VMM, displacement jumps are represented using finite elements with specially constructed discontinuous shape functions. These elements are progressively added along the crack path during fatigue failure. The stiffness of these elements changes non-linearly in response to the accumulation of damage during cyclic loading. The evolution law for stiffness is represented as a function of traction and the number of loading cycles since the initial onset of failure. Numerical examples illustrate the use of this new methodology for modeling macroscopic crack growth under Mode I loading as well as microscopic crack growth under mixed mode loading within the elastic regime. We find that the discontinuous elements can consistently predict the Mode I stress intensity factor (SIF) and the micro-structurally short crack growth paths, and that the computed Paris law for steady crack growth is controlled primarily by two parameters in the decohesion law.

Energy efficient buildings rely on simulation to predict energy performance. However, problems associated with simulation tools can lead to surprises when discrepancies are found between actual and predicted building energy performance; this frustrates building owners, investors, and designers. A probabilistic method of risk assessment for the calculation of energy use intensity and total utility cost in energy performance has been developed. Sensitive and uncertain parameters were selected and given a probability distribution instead of one fixed value for the simulations. Latin hypercube sampling was used to generate input combinations with parameter values picked stochastically from distributions based on the Monte Carlo method. With these input combinations, 10,000 simulations on seven distributed parameters were run using a cloud processing service. The output data, energy use intensity and energy cost, were analyzed using curve-fitting techniques to find a best-fit distribution, which could be used for risk analysis of energy performance and cost. The results illustrate the probability and reliability of prediction within a specific range. Instead of relying on a single value, these curves would help designers better evaluate design alternatives, and the probability distribution of energy performance and cost would be useful in making decisions about investments for energy efficient projects.

Crack propagation in a polycrystalline microstructure is analyzed using a novel multiscale model. The model includes an explicit microstructural representation at critical regions (stress concentrators such as notches and cracks) and a reduced order model that statistically captures the microstructure at regions far away from stress concentrations. Crack propagation is modeled in these critical regions using the variational multiscale method. In this approach, a discontinuous displacement field is added to elements that exceed the critical values of normal or tangential tractions during loading. Compared to traditional cohesive zone modeling approaches, the method does not require the use of any special interface elements in the microstructure and thus can model arbitrary crack paths. The capability of the method in predicting both intergranular and transgranular failure modes in an elastoplastic polycrystal is demonstrated under tensile and three-point bending loads.

The role of subchondral bone in cartilage damage attracts increasing interests in osteoarthritis (OA) research. Subchondral bone might play more important roles in cartilage damage for postmenopausal women due to estrogen’s remarkable influence on bone metabolism. However, it still lacks direct evidence on the role of subchondral bone since estrogen can influence metabolisms of cartilage and subchondral bone at the same time. This study adopted the OVX-OA rat model. Damage scores and mechanical properties of cartilage and trabecular parameters of subchondral bone were evaluated. Change ratios of all the parameters at week 9 relative to week 3 which represented alterations after OVX were calculated. The results showed that change ratios of subchondral bone and cartilage damage in femur unit were both significantly lower than those in tibia unit. The two units were under the same estrogen level. That lower cartilage damage responded to lower subchondral bone change in femur unit provided evidence that articular cartilage damage might directly be affected by mechanical environmental changes induced by subchondral bone alteration in OVX-OA. Thus, for clinics, subchondral bone might be an new treatment target for this type of OA; for numerical simulation of articular joint, subchondral bone and cartilage shouldn’t be modeled as two independent parts.