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Deep-borehole heat exchangers (DBHE) are generally coaxial pipes installed in deep boreholes and has become an alternative approach to utilize geothermal energy. Since the performance of the DBHE system can be affected by several parameters, it is important to optimize the design of parameters for the DBHE. In this paper, based on the analytical method, we carried out the sensitivity analysis of DBHE design parameters, including outer pipe diameter, inner pipe diameter, flow rate, outer pipe materials, grout materials, and borehole depth during continuous operation for 4 months. The sensitivity analysis results indicate that the heat extraction rate can be significantly affected by outer pipe diameter, borehole depth, and flow rate. The effects of grout materials, inner pipe diameter and outer pipe materials are of second-order. Finally, an optimization method based on the lowest Average Energy Cost index was proposed to optimize these DBHE design parameters under different geological conditions. Given the cost in this study, a combination scheme of all the optimal parameters is given for different depth wells under different geological conditions.

Plant diseases severely reduce crop yields and threaten global food security. Broad-spectrum resistance (BSR) is a desirable trait because it confers resistance against more than one pathogen species or the majority of races/strains of the same pathogen. To control plant diseases, breeders have selected BSR to reduce disease occurrence and prolong the life-span of newly released cultivars in the last several decades (Mundt, Phytopathology 108(7):792–802, 2018). Although effective, breeding of BSR cultivars in crop plants is still time-consuming and technically challenging. Recently, new gene-editing technologies such as CRISPR/Cas9 have dramatically accelerated the process of plant breeding and provided an approach for rapidly creating new varieties with BSR and other beneficial traits (Borrelli et al., Front Plant Sci 9:1245, 2018). In addition, close surveillance of pathogen populations in the field can provide useful information for the deployment of appropriate resistance genes in the target regions. In this mini-review, we focus on the significance and application of the exciting results from two recent companion papers published in Nature Biotechnology that provide new strategies to develop crop plants with BSR against pathogens through targeted promoter editing of susceptibility genes in plants as well as pathogen population monitoring.

Two-dimensional (2D) materials have exotic intrinsic electronic band structures and are considered as revolutionary foundations for novel nanodevices. Band engineering of 2D materials may pave a new avenue to overcome numerous challenges in modern technologies, such as room temperature (RT) photodetection of light with photon energy below their band gaps. Here, we reported the pioneering RT MoS2-based photodetection in the terahertz (THz) region via introducing Mo4+ and S2- vacancies for rational band gap engineering. Both the generation and transport of extra carriers, driven by THz electromagnetic radiations, were regulated by the vacancy concentration as well as the resistivity of MoS2 samples. Utilizing the balance between the carrier concentration fluctuation and carrier-scattering probability, a high RT photoresponsivity of 10 mA/W at 2.52 THz was realized in an Mo-vacancy-rich MoS2.19 sample. This work overcomes the challenge in the excessive dark current of RT THz detection and offers a convenient way for further optoelectronic and photonic devices based on band gap-engineered 2D materials.

Phosphate crystals typically display small birefringence, due to the very small polarizability anisotropy of the highly symmetric [PO4] tetrahedral unit. Here, we discovered a novel phosphate crystal, Te3O3(PO4)2, which exhibits an unexpectedly enhanced birefringence of 0.148 at 1064 nm, which hits a new high in inorganic phosphate materials. Theoretical calculations and structural analysis reveal that the large birefringence can be attributed to the combined effects of the highly distorted [TeO5] group and antiparallel [PO4] pseudo-layer. Notably, bulk Te3O3(PO4)2 single crystals can be grown by the Czochralski method, and a centimeter-size crystal has been successfully obtained. Moreover, the Te3O3(PO4)2 crystal exhibits a wide transmission range (0.29–4.76 μm) and a high laser damage threshold (544 MW cm−2). These excellent properties suggest that Te3O3(PO4)2 is a potential phosphate birefringent material. More importantly, this work confirmed that the distorted [TeO5] group and antiparallel [PO4] pseudo-layer are two excellent functional units for increasing birefringence, which provides a novel strategy for the further design of new phosphate compounds with large birefringence.

A new borate fluoride, Li3CaB2O5F, has been synthesized. It features a sandwich-like structure with the adjacent [Li3OF]∞ and [CaO]∞ layers connected by the weak Li–O bonds and the [B2O5] dimers. Interestingly, Li3CaB2O5F has large ionic conductivity, which is attributed to the diverse and wide Li-ion diffusion pathways.

Two new halogen-rich ortho-borates, Ba6BO3Cl9 and Pb6BO4Cl7, were synthesized and characterized. Interestingly, Pb6BO4Cl7 contains rare uncondensed BO4 tetrahedra. The structure analyses indicate that the large cation/boron ratio, the stereochemically active lone pairs on Pb2+ cations and the rich Cl- anions play key roles in the formation of the uncondensed BO4 tetrahedra.

Molecular sieves are of increasing importance in catalysis, the oil industry, and biomedicine. Traditional molecular sieves are generally oxides that inevitably show some absorption in the mid- and far-IR range due to the vibrations of metal-oxygen bonds, which are unfavorable for the in situ observation of the reactions in molecular sieves through IR techniques. In this study, a new metal halide In[Ba3Cl3F6] has been synthesized. It exhibits a quite transparent window from 0.366 to 22 μm and good adsorption and desorption processes.

Three rare-earth orthoborates Ba2MgY2(BO3)4, Ba2CdY2(BO3)4, and Ba2CdSc(BO3)3 were synthesized via a high-temperature solution method and their structures were determined by single crystal X-ray diffraction for the first time. Ba2MgY2(BO3)4 and Ba2CdY2(BO3)4 are isostructural and both crystallize in the monoclinic crystal system, P21/c, while Ba2CdSc(BO3)3 crystallizes in the triclinic crystal system, P. The structures of Ba2MgY2(BO3)4 and Ba2CdY2(BO3)4 can be described as the three-dimensional (3D) frameworks composed of MO5 (M = Mg, Cd), YOn (n = 6, 7) polyhedra with isolated BO3 and Ba2+ cations residing in the space of the frameworks. The structure of Ba2CdSc(BO3)3 is composed of 2D [CdSc(BO3)3]∞ layers separated by Ba2+ cations. In addition, structural comparisons, thermal behaviors, UV-vis-NIR diffuse reflectance spectra, and infrared spectroscopy results are also reported.

Three phosphates Rb2Zn3(P2O7)2 and Cs2M3(P2O7)2 (M = Zn and Mg) were successfully synthesized by a high-temperature solution method. Their structures were determined by single-crystal X-ray diffraction, which shows that the three structures all display three-dimensional [M3P4O20]14− (M = Zn and Mg) frameworks composed of isolated P2O7 dimers and MO4 (M = Zn and Mg) tetrahedra with Rb+/Cs+ cations located in the space of the frameworks to balance charges. But owing to the cationic size effect, they are not iso-structural. Rb2Zn3(P2O7)2 crystallizes in the non-centrosymmetric P21 space group, whereas Cs2M3(P2O7)2 (M = Zn and Mg) crystallize in the centrosymmetric P21/c space group. And Rb2Zn3(P2O7)2 exhibits a second harmonic generation (SHG) response as large as that of KH2PO4 (KDP). Combining electronic structure and SHG density calculations, we studied the effects of ZnO4 tetrahedra on the SHG response of Rb2Zn3(P2O7)2. Furthermore, a structural comparison is also carried out in Rb2Zn3(P2O7)2 and Cs2M3(P2O7)2 (M = Zn and Mg).

Introduction of Pb2+ cations in silicate systems generates a new compound, PbSrSiO4, which exhibits excellent properties, including a strong second harmonic generation response (∼5.8 × KDP), a short UV cut-off edge (240 nm) and moderate birefringence (0.053@1064 nm). These results suggest that PbSrSiO4 is a promising UV NLO material.

Polymorphic α- and β-BaTi(IO3)6 have been synthesized. They crystallize in the same space group and exhibit highly similar structures. But the different powder X-ray patterns and crystal morphologies indicate that they belong to different phases, which represents the first phase transitions with two polymorphs possessing the same space group and similar cells.

Assessment of available heat capacity in the shallow ground is important to the development of ground source or geothermal heat pumps. A new volumetric method-based approach is proposed for evaluating shallow geothermal potential by combining microtremor survey results. Parameters such as thickness of clay and sandy gravel layers can be achieved by processing the microtremor filed data. The study area was divided into grids based on the different exploration sites. The heat present in each small unit was calculated using the revised volumetric method. This division into small units improved the accuracy of assessment of the geothermal potential and helped plot the distribution map of the available heat amount, which indicated optimal locations for development and utilization of shallow geothermal resources. Jimo, China was used as an example to depict the calculation flow. Since the microtremor survey method can identify the thickness of clay, sandy gravel, and fresh bedrock layers in shallow ground, the amount of shallow geothermal resources present above fresh bedrock was calculated. In Jimo, the amount of exploitable geothermal resources, using the traditional volumetric method, was found to be 4.92 × 1012 kJ. The proposed calculation method not only provided a higher corresponding value of 6.96 × 1012 kJ but also showed the regions with the highest potential of shallow geothermal resources. Hence, this approach provides an alternative method for geothermal potential assessment which can be used globally.

A series of KDP crystals at different rotation speeds ranging from 9 to 120 rpm were grown by rapid growth method. The results fully demonstrate that rotation speed as a key kinetic parameter has a great influence on the whole crystallization process. Moreover, an important characteristic has been proved that the growth rates along X and Z-direction increase with the increase of rotation speed lower than 100 rpm, while the rates of X-direction are always greater than Z-direction. Combined with numerical simulation method, the correlations of solution stability with kinetic factors including rotation speed, crystal size and growth platform are explored in detail. During the crystallization process, the thickness of boundary layer decrease and a higher flow rate is caused with the increase of rotation speed below 100 rpm, and the generation of inclusions at lower speed may be associated with the slower flow rate of growth solution. The stability of solution gradually decreases as the rotation speed ranges from 100 to 120 rpm. Furthermore, the computed results of Re imply that reducing rotation speed as increasing of crystal size may be an effective method to obtain high-quality and large-scale KDP crystal by rapid growth technique. Comparing to the growing platform with four columns, the platform with two circular connecting columns play an active role in influencing the growth rate of KDP crystal, especially in axial direction.

Electron-phonon coupling emerges as a growing frontier in the heart of condensed matter from physical symmetry to the electronic quantum state, but its quantitative strength dependence on the chemical structure has not been assessed. Here, we originally proposed the anion-centered polyhedron (ACP) strategy for elaborating the electron-phonon coupling interaction in rare-earth (RE) materials comprising three chemical factors, RE-O bond length, the effective charge of the coordinated atom, and structural dimensionality. Using Gd

Borophosphates are an ideal material class for the design of deep-UV optical functional crystals, yet their practical applications are limited by their small birefringence. Herein, a new mixed-coordinated borophosphate, NH

Inorganic heteroanionic materials are attracting increasing attention for exploring new nonlinear optical (NLO) materials because they could better satisfy the necessary but conflicting properties of NLO crystals, e.g. large SHG response and wide band-gap. Up to now, the reports on heteroanionic NLO materials have mainly focused on ultraviolet or visible oxide-based fluoroborates, fluorophosphates, borate-phosphates and borate-iodates. However, chalcogenides containing different kinds of anionic groups have barely been reported. Herein, we have synthesized the first oxychalcogenide-carbonate, Sr

Rice false smut caused by Ustilaginoidea virens is becoming one of the most recalcitrant rice diseases worldwide. However, the molecular mechanisms underlying rice immunity against U. virens remain unknown. Using genetic, biochemical and disease resistance assays, we demonstrated that the xb24 knockout lines generated in non-Xa21 rice background exhibit an enhanced susceptibility to the fungal pathogens U. virens and Magnaporthe oryzae. Consistently, flg22- and chitin-induced oxidative burst and expression of pathogenesis-related genes in the xb24 knockout lines were greatly attenuated. As a central mediator of energy signaling, SnRK1A interacts with and phosphorylates XB24 at Thr83 residue to promote ATPase activity. SnRK1A is activated by pathogen-associated molecular patterns and positively regulates plant immune responses and disease resistance. Furthermore, the virulence effector SCRE1 in U. virens targets host ATPase XB24. The interaction inhibits ATPase activity of XB24 by blocking ATP binding to XB24. Meanwhile, SCRE1 outcompetes SnRK1A for XB24 binding, and thereby suppresses SnRK1A-mediated phosphorylation and ATPase activity of XB24. Our results indicate that the conserved SnRK1A-XB24 module in multiple crop plants positively contributes to plant immunity and uncover an unidentified molecular strategy to promote infection in U. virens and a novel host target in fungal pathogenesis.

Oxychalcogenides with the performance-advantages of both chalcogenides and oxides are emerging materials class for infrared (IR) nonlinear optical (NLO) crystals that can expand the wavelength of solid-state lasers to IR regions and are of importance in industrial and civil applications. But rationally designing a high-performance oxychalcogenide NLO crystal remains a great challenge. Herein, we chose the melilite-type Sr

As a clean energy source, the role of wind power in the energy mix is becoming increasingly important. Reliable and high-quality wind speed prediction results are key to wind energy utilization. The traditional point prediction method cannot effectively analyze the uncertainty of wind speed, and the interval prediction model can provide the possible variation range of wind speed under a certain confidence probability and supply more uncertain information to decision makers. However, the previous interval prediction models generally ignore the random characteristics of capturing wind speed and the importance of objective selection of prediction submodels, leading to poor prediction results. To address these problems, a combined model based on data preprocessing, multi-neural network models, multi-objective optimization, and an improved interval prediction method is proposed. The model is applied to five wind speed forecasting examples in Dalian to test the prediction accuracy, multi-step prediction ability, and universality and generalization ability of the model. The experimental results show that the model proposed in this study is satisfactory for various performance evaluation indexes, has high stability and accuracy, and all the solutions obtained by the model are Pareto optimal solutions. Thus, it provides a reliable reference for the effective utilization of wind energy.

Discovering new mid-IR nonlinear optical (NLO) materials with high laser damage thresholds and easy crystal growth is an urgent and challenging task. Through cationic substitution of Si4+ in Li2K4(...

By the combination of the isolated P2O7 dimers and MgO4 tetrahedra, α- and β-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method. α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space group P 212121, while β-Rb2Mg3(P2O7)2 crystallizes in centrosymmetric P 21/ c . Both structures contain a three dimensional [Mg3P4O14]2− anionic framework, while Rb+ cations are in the space. Structure analyses show that the isolated P2O7 dimers can easily adjust their variable configurations and orientations to fit the different coordination environments of the cations, which is conducive to the formation of polymorphs. The phase transformation process from α- to β-Rb2Mg3(P2O7)2 was further investigated by powder X-ray diffraction and thermal gravimetric/differential scanning calorimetry measurements. In addition, UV-vis-NIR diffusion spectra indicate both materials have deep-ultraviolet cut-off edges (below 190 nm). α-Rb2Mg3(P2O7)2 is second-harmonic generation (SHG)-active and the origin of SHG response was investigated by the SHG density calculations. The first-principle calculations were also carried out to illuminate their structure-property relationships.

Predicting workload using physiological sensors has taken on a diffuse set of methods in recent years. However, the majority of these methods train models on small datasets, with small numbers of channel locations on the brain, limiting a model's ability to transfer across participants, tasks, or experimental sessions. In this paper, we introduce a new method of modeling a large, cross-participant and cross-session set of high density functional near infrared spectroscopy (fNIRS) data by using an approach grounded in cognitive load theory and employing a Bi-Directional Gated Recurrent Unit (BiGRU) incorporating attention mechanism and self-supervised label augmentation (SLA). We show that our proposed CNN-BiGRU-SLA model can learn and classify different levels of working memory load (WML) and visual processing load (VPL) across participants. Importantly, we leverage a multi-label classification scheme, where our models are trained to predict simultaneously occurring levels of WML and VPL. We evaluate our model using leave-one-participant-out (LOOCV) as well as 10-fold cross validation. Using LOOCV, for binary classification (off/on), we reached an F1-score of 0.9179 for WML and 0.8907 for VPL across 22 participants (each participant did 2 sessions). For multi-level (off, low, high) classification, we reached an F1-score of 0.7972 for WML and 0.7968 for VPL. Using 10-fold cross validation, for multi-level classification, we reached an F1-score of 0.7742 for WML and 0.7741 for VPL.

Infrared nonlinear optical (IR NLO) crystals play a significant role in the development of IR laser technology. But rationally designing a new IR NLO crystal remains a huge challenge because of the unpredictability of inorganic structures. Herein, inspired by phase transformation of the famous BaB2 O4 (BBO) crystal, a temperature-induced centrosymmetric (CS) to noncentrosymmetric (NCS) transformation approach is employed in CS BaGa2 Se4 to uncover a new NCS ternary chalcogenide, β-BaGa2 Se4 which can exhibit the well-balanced NLO properties, including moderate phase-matching SHG response (≈0.6×AgGaS2 ), high LDT (10×AgGaS2 ), and large birefringence (Δn=0.18 in the visible region). Therefore, β-BaGa2 Se4 will be a promising IR NLO crystal. The analysis for the structure-property relationship shows that the excellent NLO properties of β-BaGa2 Se4 mainly originate from edge-sharing GaSe4 tetrahedral chains, which are different from B3 O6 groups in β-BBO and respect a new direction for the design of IR NLO crystals. So, we believe that the current research provides not only a new IR NLO crystal but also some insights for the design of new IR NLO crystals.

Mitochondria are energy factories of cells and are important for intracellular interactions with other organelles. Emerging evidence indicates that mitochondria play essential roles in the response to pathogen infection. During infection, pathogens deliver numerous enzymes and effectors into host cells, and some of these effectors target mitochondria, altering mitochondrial morphology, metabolism, and functions. To defend against pathogen attack, mitochondria are actively involved in changing intracellular metabolism, hormone-mediated signaling, and signal transduction, producing reactive oxygen species and reactive nitrogen species and triggering programmed cell death. Additionally, mitochondria coordinate with other organelles to integrate and amplify diverse immune signals. In this review, we summarize recent advances in understanding how mitochondria function in plant immunity and how pathogens target mitochondria for host defense suppression.

Metal iodates are of current research interest because of their potential application as nonlinear optical crystals but the exploration of new iodates is mainly concentrated on complex cation iodates. In contrast, iodates with multiple anion groups are rarely reported. In this communication, the first noncentrosymmetric alkaline-metal iodate-sulfate, Na

The Xanthomonas outer protein C2 (XopC2) family of bacterial effectors is widely found in plant pathogens and Legionella species. However, the biochemical activity and host targets of these effectors remain enigmatic. Here we show that ectopic expression of XopC2 promotes jasmonate signaling and stomatal opening in transgenic rice plants, which are more susceptible to Xanthomonas oryzae pv. oryzicola infection. Guided by these phenotypes, we discover that XopC2 represents a family of atypical kinases that specifically phosphorylate OSK1, a universal adaptor protein of the Skp1-Cullin-F-box ubiquitin ligase complexes. Intriguingly, OSK1 phosphorylation at Ser53 by XopC2 exclusively increases the binding affinity of OSK1 to the jasmonate receptor OsCOI1b, and specifically enhances the ubiquitination and degradation of JAZ transcription repressors and plant disease susceptibility through inhibiting stomatal immunity. These results define XopC2 as a prototypic member of a family of pathogenic effector kinases and highlight a smart molecular mechanism to activate jasmonate signaling., XopC2 effectors are present in many plant bacterial pathogens. Here the authors show that XopC2 has kinase activity and enhances disease susceptibility by phosphorylating the OSK1 protein, which increases its interaction with the jasmonate receptor COI1b to promote JA signaling and stomatal opening.

The nonlinear optical (NLO) crystals that can expand the wavelength of the laser to the deep-ultraviolet (DUV) region by the cascaded second harmonic generation (SHG) are of current research interest. It is well known that borates are the most ideal material class for the design of new DUV NLO crystals owing to the presence of good NLO genes, e.g., BO3 or B3O6 groups. However, the NLO pyro-borates with the B2O5 dimers as the sole basic building units are still rarely reported owing to their small SHG responses. In this communication, by constructing a planar pentagonal [Ca(B2O5)]∞ layer, the NLO pyro-borate Ba4Ca(B2O5)2F2 with a large SHG response (∼2.2 × KDP, or ∼7 × α-Li4B2O5) and a DUV transparent window has been designed and synthesized. The first-principles calculations show that the large SHG response of Ba4Ca(B2O5)2F2 mainly originates from the better π-conjugation of the coplanar B2O5 dimers in the [Ca(B2O5)]∞ layer. In addition, the planar pentagonal pattern in the [Ca(B2O5)]∞ layer provides an ideal template for designing the new DUV NLO crystals, apart from those in known DUV borates, e.g., the [Be2BO3F2]∞ layer in KBe2BO3F2 (KBBF)., A new deep-UV NLO pyro-borate Ba4Ca(B2O5)2F2 was synthesized by solid-state reactions. The better π-conjugation of B2O5 dimers in the planar pentagonal layer achieves a large SHG response (∼2.2 × KDP), which is the largest among all the known DUV transparent borates with B2O5 units.

A new borotellurite, LaTeBO

Dimethylaminoethyl methacrylate maleate (DMAEMA–MA) polymerizable ionic liquid was synthesized from 2-(dimethylamino)ethyl methacrylate and maleic acid and characterized by 1HNMR and FTIR. IC-P hydrogel was prepared by hydrothermal synthesis method using 2-acrylamide-2-methylpropane sulphonic acid and acrylamide as monomers, DMAEMA–MA as crosslinker and potassium peroxodisulphate as initiator. BIS-P hydrogel was prepared by using N,N′-methylene bisacrylamide (BIS) as non-ionic crosslinker, and the performances of BIS-P and IC-P hydrogels were compared. The results showed that IC-P hydrogel had a pore structure similar to BIS-P. When the dosage of DMAEMA–MA was 1.6% (based on the total mass of monomers), the swelling rate of the prepared IC1.6 hydrogel in water can reach 235.97%, the conductivity was 58.8 μS cm−1, and the derusting effect of Q235 low carbon steel with rust grade C could reach grade A. Moreover, DMAEMA–MA could improve the thermal stability of IC-P hydrogel.

The controllable incorporation of the dopant element with strictly designed coordination geometry into the target host merits untold scientific and technological potential, yet it has been met with...

To investigate the influence of modified clivoaxial angle (MCAA) on the surgical planning and outcome in adult patients with Chiari malformation type I.Clinical data of 268 adult patients undergoing posterior fossa decompression without (PFD) or with duraplasty (PFDD) or with resection of tonsils (RT) for Chiari malformation type I over 10 years were reviewed retrospectively, with outcome evaluated by Chicago Chiari Outcome Scale (CCOS) score. By means of receiver operating characteristic curve, the threshold of MCAA was calculated to stratify the patients.MCAA was positively correlated with CCOS score. In the MCAA ≤ 127° group (n = 57) with severe ventral cervicomedullary compression (VCMC), CCOS score of PFD, PFDD, and RT was 11.00, 11.06, and 12.42 (P0.05), respectively. In the 127°MCAA ≤ 138° group (n = 87) with moderate VCMC, CCOS score of PFD, PFDD, and RT was 11.71, 12.72, and 13.00 (P0.01), respectively. In the MCAA138° group (n = 124) with mild or no VCMC, CCOS score of PFD, PFDD, and RT was 13.19, 13.90, and 13.67 (P 0.05), respectively. The mean MCAA increased by 4.4° postoperatively (P0.05), which was positively associated with syringomyelia shrinkage.MCAA may play a role in guiding the surgical treatment and predicting the prognosis in adult CMI patients. The larger the MCAA, the less invasive surgery is preferred with higher CCOS. PFDD should be the first choice in patients with mild or no VCMC (MCAA138°) and RT in patients with moderate VCMC (127°MCAA ≤ 138°). For patients with severe VCMC (MCAA ≤ 127°), RT could be considered as the primary surgery with awareness of the possible insufficiency of posterior decompression alone.

Mid-infrared electro-optic Q-switched lasers with high repetition rates have many vital applications. However, the required voltage of electro-optic Q-switching is proportional to the wavelength leading to the severe piezoelectric ring effect, which limits its developments especially with high repetition rates. Based on the rate equation, this work designs a Langasite (LGS) electro-optic Q-switched laser with high repetition rates at 2 μ m by balancing the gain and loss in the cavity. The driven voltage determines the rotation of the polarization corresponding the loss in the cavity, and the gain depends on the incident pump power and repetition rate. By theoretical calculation, the driven voltage used in the high repetition rates is reduced to be 3.9 kV, which is 45% lower than the quarter-wave voltage. We demonstrated the LGS electro-optic Q-switched 2 μ m laser with a repetition rate of 200 kHz and pulse width of 5.52 ns. To the best of our knowledge, this work presents the highest repetition rate in the electric–optic Q-switched laser at 2 μ m and should be helpful for the design of Q-switched lasers with high repetition rates.

Compared to unstiffened circular hollow section (CHS) X-joints, CHS X-joints stiffened with external ring stiffeners and gusset plates have exhibited much higher bearing capacity. To gain insight into the effects of the chord pre-loads on ultimate bearing capacity, this paper presents results of finite element (FE) analyses of the stiffened X-joints with braces under compression and chord under (i) axial load, (ii) in-plane bending moment, or (iii) combinations of axial load and in-plane bending moment. Precision of the FE model under combined brace and chord loads is validated by test results. The ultimate bearing capacities attained by using proportional loading and non-proportional loading respectively are presented, and the results indicate that the differences due to loading path are negligible. The validated FE modelling technologies are then employed in a parametric study on the effect of chord pre-load. A total of 4560 stiffened X-joints are examined in the parametric study. The theoretical analysis presented herein provides a reasonable explanation for the significant reduction in strength of stiffened X-joint when the chord is under axial tension. Finally, a chord stress function with corresponding boundary conditions is proposed, in which the coefficients for different chord load cases are determined through regression analysis. Furthermore, a lower-bound multiplier is given for the function to ensure a conservative design.

Design and fabrication of high-strength and low-thermal-conducting cement-based materials are urgently needed for developing low-energy-consuming buildings. Here glass bead (GB) and ground expanded perlite (EP) particles were respectively used as the macro and micro insulating fillers to synthesize thermally insulating cement-based composites (C-GB-EP). The material structures, mechanical and thermal properties of the C-GB-EP composites were investigated by comprehensive experimental tests. Results indicate that both fillers have no obvious influences on cement hydration, but accelerate the carbonation of calcium hydroxide due to the loosely compacted microstructures. The C-GB-EP composites show complex and multi-scaled material structures dominated by the interactions between the fillers and matrices in different scales. The C-GB-EP composites retain their mechanical properties in the limited EP contents. The C-GB-EP composites show relatively low thermal conductivities and very high thermal-resistant abilities with respect to compressive strength and density. A multi-scale micromechanical model was proposed to predict the effective thermal conductivity of the composites. Inclusion shapes play an important role on depressing the thermal conductivity of composites. Incorporation of penny-shaped insulating inclusions in cement matrix may be an appropriate and effective way to design new types of thermally insulating cement-based composites.

The welded hollow spherical joint (WHSJ) with diameter greater than 1.0 m is commonly employed in long-span tubular transmission towers. It has a relatively higher ratio of diameter to thickness compared to traditional spherical joints, since the larger thickness leads to difficulties in fabricating a spherical joint with a diameter of more than 1.0 meter, and will also lead to deterioration of mechanical properties of materials. Therefore, longitudinal and transverse stiffeners are usually set inside to avoid local buckling and improve bearing capacity. In this study, experimental tests and finite element (FE) analyses of full-scale WHSJs with a diameter of 1400 mm under the multi-axial load are conducted. The results indicate that all specimens have similar failure modes, namely the indentation of the hollow sphere near the main tube, and the failure of the longitudinal stiffeners at the same position. In addition, the setup of longitudinal stiffeners would obviously improve the ultimate bearing capacity (UBC) of WHSJ. After the validity of the FE model is verified, the parametric study is carried out. The results indicate that the UBC of stiffened WHSJ can be approximated by the sum of the resistances of the corresponding unstiffened WHSJ and the stiffeners. Accordingly, design equations are proposed for stiffened WHSJs with diameter greater than 1.0 m. The results obtained by proposed equations are compared with that obtained by tests and FE analyses. They are basically in good agreement, which shows the validity of the equations.

This study reported the capillary imbibition of ethanol in a cement paste traced by X-ray computed tomography (X-CT) enhanced by CsCl. Results show that CsCl can promote the contrast of X-CT images due to the significant X-ray absorption of Cs. The grey value distributions of horizontal section images were calculated to identify the penetration fronts of the CsCl-ethanol solution in the cement paste. The relationship between imbibition height and time follows the Lucas-Washburn equation. The method of enhancing X-ray sorption by CsCl paves a wide path to in situ monitor liquid imbibition in porous materials for assessing their microstructures and properties.

Efficient, high-power ultrafast lasers and their further chirped pulse amplification (CPA) are important for modern science, which requires the laser medium with high thermal conductivity, low phon...