The process of bamboo-oriented strand lumber (BOSL) represents one of the best opportunities for automation, property control and consistency, and high utilization of material from abundant, ...fast-growing, and sustainable bamboo. In this study, BOSLs were prepared, with reference to the preparation process of bamboo scrimber, by compressing and densifying constituent units under the action of moisture-heat-force and resin polymerization, and then the effects of density variation on their physical and mechanical properties were investigated. The results revealed that the modulus of rupture, modulus of elasticity, compressive strength and shear strength of BOSL with density of 0.78–1.3 g/cm3 ranged from 124.42 to 163.2 MPa, 15,455 to 21,849 MPa, 65.02 to 111.63 MPa, and 9.88 to 18.35 MPa, respectively. The preparation of BOSL with bamboo as raw material could retain the good mechanical properties of natural bamboo, and produce bamboo-based structural products with different properties by controlling the density. The high strength of BOSL with high density was primarily due to the increased volume fraction of elementary fibers, the reduced porosity, and the enhanced gluing interface. The performance of BOSL can be comparable to, or surpass that of, wood or bamboo products. This study provided necessary basic research for the engineering design and application of BOSL.
Arbuscular mycorrhizal fungi (AMF) have established themselves as pivotal allies in the realm of plant physiology, renowned for their remarkable contributions to augmenting both growth and resilience ...against environmental stresses. In this study, we embarked on a comprehensive investigation into the discernible impact of two distinct AMF species on a widely planted oat cultivar, ‘Qingyan No. 1’, when subjected to the austere conditions of a drought. The experimental design included three distinct AMF treatments (inoculation with Rhiaophagus intraradices, Funneliformis mosseae, or not), and the three water treatments were 75% of field capacity (well watered), 50% of field capacity (moderate drought), and 30% of field capacity (severe drought). The obtained results showed that the rate of inoculation under 75% FC for both AMF species was over 74%. Drought stress limited the growth and osmotic regulation of the oat plants. However, AMF inoculation observably increased the above-ground biomass under 75% FC and increased the root biomass under 30% FC. AMF inoculation also increased the root traits under 75% FC and 50% FC. R. intraradices inoculation increased the above-ground soluble sugar and soluble protein concentrations, and both AMF species showed decreased malondialdehyde (MDA) concentrations in the roots. Furthermore, the pervasive influence of drought stress exerted a discernible stranglehold on nutrient uptake in the oat plants, profoundly impacting the distribution of nutrients within the shoots and roots. Regardless of the drought stress treatment, the inoculation with both AMF species increased the P concentrations in the roots and the K and Mg concentrations in the roots, and the inoculation with R. intraradices increased the Ca concentration in the whole oat plant. Under 75% FC, the N concentration of the whole oat plant was significantly reduced by both AMF species. However, under 50% FC and 30% FC, the N concentrations in the shoots inoculated with both AMF species were close to that of the non-inoculated shoots. In summary, AMF improved the osmotic regulation and nutrient absorption and distribution of oat plants under drought stress and thus promoted the growth and biomass accumulation of oat plants.
Heterogeneous Feature Fusion Machines (HFFM) is a kernel based logistic regression model that effectively fuses multiple features for visual recognition tasks. However, the batch mode solution for ...HFFM, ‘Block Coordinate Gradient Descent’ (BCGD) has the same low efficiency and poor scalability as the most batch algorithms do. In this paper, we describe a newly developed online learning algorithm in multiple Reproducing Kernel Hilbert Spaces for solving HFFM model. This new algorithm is called OLHFFM, i.e. Online HFFM. OLHFFM is novel combination of kernel-based learning technique with dual averaging gradient descent methods. In addition, group LASSO regularization technique is used in OLHFFM for finding important explanatory coefficients that are related to support samples in group manner. The effectiveness of OLHFFM has been demonstrated by a number of experiments that were conducted on public event, object dataset, as well as on large scale handwritten digital dataset. Using the OLHFFM approach, we have achieved almost equivalent recognition performance to that using batch-mode approach. Experiments conducted on both MIT Caltech-6 and challenging VOC2011 TrainVal object datasets show that OLHFFM is superior in performance to kernel based online learning approaches such as ILK or NORMA. In addition, the classification performance of OLHFFM approach as demonstrated by the experiments conducted on large scale MNIST dataset is comparable to or better than that of the current state-of-the-art online multiple kernel learning approaches such as OM-2, UFO-MKL, OMCL and OMKL. Extensive experiments on visual data classification demonstrate the effectiveness and robustness of the new OLHFFM approach.
The mitochondrial genomes of seed plants are unusually large and vary in size by at least an order of magnitude. Much of this variation occurs within a single family, the Cucurbitaceae, whose genomes ...range from an estimated 390 to 2,900 kb in size. We sequenced the mitochondrial genomes of Citrullus lanatus (watermelon: 379,236 nt) and Cucurbita pepo (zucchini: 982,833 nt)--the two smallest characterized cucurbit mitochondrial genomes--and determined their RNA editing content. The relatively compact Citrullus mitochondrial genome actually contains more and longer genes and introns, longer segmental duplications, and more discernibly nuclear-derived DNA. The large size of the Cucurbita mitochondrial genome reflects the accumulation of unprecedented amounts of both chloroplast sequences (>113 kb) and short repeated sequences (>370 kb). A low mutation rate has been hypothesized to underlie increases in both genome size and RNA editing frequency in plant mitochondria. However, despite its much larger genome, Cucurbita has a significantly higher synonymous substitution rate (and presumably mutation rate) than Citrullus but comparable levels of RNA editing. The evolution of mutation rate, genome size, and RNA editing are apparently decoupled in Cucurbitaceae, reflecting either simple stochastic variation or governance by different factors.
•The paper focus on the high-value utilization of bamboo used for structural materials. Bamboo strand-based structural composite lumber (BSCL) were prepared.•Their production process has the ...characteristic of high raw material utilization ratio and high level of automation.•The research showed that the MOR as high as 300 MPa and MOE of BSCL as high as 30000 MPa were obtained.•BSCLs have potential to be considered as a high performance alternative to wood-based Structural Composite Lumber.
In order to make efficient and high-value utilization of bamboo materials, bamboo strand-based structural composite lumber (BSCL) with high bamboo utilization, high automation level and excellent performance was prepared. The influence of technological parameters, including strand thickness, strand length and resin content, on the performance of BSCLs was analyzed under the mutual function of board density. The results showed that board density and resin content have a significant effect on the water resistance properties of BSCL. With increasing resin contents and densities, most water resistance properties increased. It was also revealed that the density has a significant influence on mechanical properties. The modulus of rupture, modulus of elasticity, compressive strength and shear strength of BSCL with density of 0.73–1.32 g/cm3 ranged from 64.63 MPa to 328.18 MPa, 13354 MPa to 29340 MPa, 24.27 MPa to 158.26 MPa, 5.48 MPa to 36.22 MPa, respectively. In addition, strand length had notable influence on modulus of rupture and shear strength of board with a density of 0.9 g/cm3. But mechanical properties did not significantly vary with strand thickness and resin content. The mechanical properties of BSCL could be comparable or surpass that of wood or bamboo products. This study provided necessary basic research for engineering design and application of BSCL.
Aiming at the problem of the loss of 3D point cloud, due to the occlusion of the field of view in the 3D measurement process, a measurement scheme based on line-structured light with dual-camera is ...given. In addition, in the line-structured light measurement technology, the traditional light plane calibration is more complicated, and the three-dimensional measurement accuracy is relatively low. For this reason, this paper used the binocular polar line constraint to calibrate the physical parameters of the light plane. Experimental results show that the dual-camera measurement system can obtain high-precision global measurement results. The maximum measurement error is 0.091 51 mm, and the average measurement error is 0.076 05 mm. Compared with the traditional binocular matching method and the traditional laser triangulation method, this method can deal with the problem of field occlusion more effectively, thereby reducing the loss of measurement information in the measurement process.
We developed a criterion-referenced student rating of instruction (SRI) to facilitate formative assessment of teaching. It involves four dimensions of teaching quality that are grounded in current ...instructional design principles: Organization and structure, Assessment and feedback, Personal interactions, and Academic rigor. Using item response theory and Wright mapping methods, we describe teaching characteristics at various points along the latent continuum for each scale. These maps enable criterion-referenced score interpretation by making an explicit connection between test performance and the theoretical framework. We explain the way our Wright maps can be used to enhance an instructor's ability to interpret scores and identify ways to refine teaching. Although our work is aimed at improving score interpretation, a criterion-referenced test is not immune to factors that may bias test scores. The literature on SRIs is filled with research on factors unrelated to teaching that may bias scores. Therefore, we also used multilevel models to evaluate the extent to which student and course characteristic may affect scores and compromise score interpretation. Results indicated that student anger and the interaction between student gender and instructor gender are significant effects that account for a small amount of variance in SRI scores. All things considered, our criterion-referenced approach to SRIs is a viable way to describe teaching quality and help instructors refine pedagogy and facilitate course development.
Geographic barriers and Quaternary climate changes are two major forces driving the evolution, speciation, and genetic structuring of extant organisms. In this study, we used Pinus armandii and ...eleven other Asian white pines (subsection Strobus, subgenus Pinus) to explore the influences of geographic factors and Pleistocene climatic oscillations on species in South China, a region known to be centers of plant endemism and biodiversity hotspots. Range-wide patterns of genetic variation were investigated using chloroplast and mitochondrial DNA markers, with extensive sampling throughout the entire range of P. armandii. Both cpDNA and mtDNA revealed that P. armandii exhibits high levels of genetic diversity and significant population differentiation. Three geographically distinct subdivisions corresponding to the Qinling-Daba Mountains (QDM), Himalaya-Hengduan Mountains (HHM) and Yungui Plateau (YGP) were revealed in mainland China by cpDNA. Their break zone was located in the southeastern margin of the Qinghai-Tibetan Plateau (QTP). A series of massive mountains, induced by the QTP uplift, imposed significant geographic barriers to genetic exchange. The disjunct distribution patterns of ancestral haplotypes suggest that a large continuous population of the white pines may have existed from southwest to subtropical China. Repeated range shifts in response to the Pleistocene glaciations led to the isolation and diversification of the subtropical species. The two Taiwanese white pines share a common ancestor with the species in mainland China and obtain their chloroplasts via long-distance pollen dispersal from North Asian pines. Distinct genetic patterns were detected in populations from the Qinling-Daba Mountains, Yungui Plateau, Himalaya-Hengduan Mountains, and subtropical China, indicating significant contributions of geographic factors to the genetic differentiation in white pines. Our study depicts a clear picture of the evolutionary history of Chinese white pines and highlights the heterogeneous contributions of geography and Pleistocene climatic fluctuations to the extremely high plant species diversity and endemism in South China.
This study examined a new form of pervasive gender inequality: the gender gap among high achievers in math and considered its implication for developing STEM talents. Using the cross-nation Programme ...for International Student Achievement (PISA) data from both 2003 and 2012, we examined the mathematics gender gap among 15-year-old high achievers across ten countries/regions. We showed a consistent male advantage among the top performers in mathematics. Follow-up regression analyses revealed that the gap was associated with some socio-demographic and schooling/attitudinal variables, even after controlling for the background variables. We argue that education communities should acknowledge and address this form of gender inequality, as it could have ramifications for the science, technology, engineering, and mathematics (STEM) education pipeline. Educators and society in general still face challenges in closing the gender gap among high achievers in math with an aim to develop a gender-balanced STEM talent pool.
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