Timber and bamboo, as key green materials, are pivotal for sustainable prefabricated structures, whose performance often depends on dowel-type connections. Under perpendicular-to-grain loading, these connections are prone to brittle splitting failure. This study presents a comprehensive experimental and analytical investigation into the mechanical performance of perpendicular-to-grain bolted steel-to-timber connections. An extensive experimental program, comprising 391 specimens in 62 test series, was conducted to evaluate embedment property, slip modulus, ductility, load-bearing capacity, and bolt group effects. Analysis of 242 full-hole bending specimens revealed that the embedment behavior of glued laminated bamboo differs significantly from that of timber, and that such specimens cannot provide reliable perpendicular-to-grain embedment strength for yield capacity prediction of dowel-type connections. Among design codes, the embedment strength model in CSA O86 demonstrated superior accuracy when validated against yield capacity data, whereas other codes showed significant deviations. The study further examines the factors governing the initial and ultimate slip moduli, leading to the establishment and validation of a new calculation method for the initial slip modulus in single-bolt connections. Finally, based on the single- and multi-bolt tests, the research investigates slip modulus, ductility coefficients, failure characteristics of multi-bolt connections, yield and splitting capacities, the effective number of bolts, and provides essential considerations for engineering design.

Kiwifruit is widely cultivated for its high vitamin C content and nutritional value. In January 2022, root rot symptoms were found in about 30% of Actinidia chinensis cv. Jinyan plants grafted on A. deliciosa rootstocks in an orchard located in Sanming (26.32°N, 117.23°E), Fujian Province of China. The affected plants appeared stunted, with brown and decaying roots, some of which were covered with white hyphae. To isolate the pathogen, the surfaces of typical symptomatic roots were sterilized for 30 s using 75% ethanol, followed by four rinses in sterile water, placing on potato dextrose agar (PDA), and incubating away from light at 25°C for 7 days. 16 Globisporangium-like isolates were obtained through hyphal tip isolation, displaying a milky-white appearance with irregular protuberances on the surface, and yellow-white backs with radial fold lines. The isolates were then cultured on corn meal agar for 5 days at 25°C in dark for morphological characteristics. Under microscope, the hyphae appeared as long strips without septa and 4.1 to 8.2 µm wide (average 6.7 µm), containing irregularly sized spherical droplets. Both terminal and intercalary hyphae swellings were observed; these appeared either spherical or subspherical, with some having projections. Their dimensions were 12.3 to 27.6 µm (average 17.3 µm). The oospores were mostly spherical, either plerotic or aplerotic, 11.8 to 22.3 µm wide (average 18.9 µm), with occasional projections. The antheridia were rod-shaped and curved, with one end attached to the oogonia. Amplification of the sequences of internal transcribed spacer (ITS) regions and cytochrome c oxidase subunit I (COI) were conducted using the primers ITS1/ITS4 (White et al. 1990) and OomCoxI-Levlo/OomCoxI-Levup (Robideau et al. 2011), respectively. The sequencing results revealed identical ITS and COI sequences in all 16 isolates. BLASTn analysis of the 969-bp ITS sequence ON202808 showed 99.38-99.59% similarity (965/971bp, 967/971bp) with the KJ162353 and AY598701 sequences from Globisporangium spinosum isolates, while the 700-bp COI sequence ON075783 showed 100% and 99.41% identity (680/680bp, 676/680bp) with the GenBank sequences HQ708835 and HQ708832, respectively, from G. spinosum. Phylogenetic analysis also showed that the obtained isolate (termed MA16) clustered with isolates from G. spinosum on the same evolutionary branch. For pathogenicity testing, four-month-old healthy Jinyan (A. chinensis) plants grown in sterilized media were transferred to sterile petri dishes covered with wet filter paper, and their roots were inoculated with a 5-mm-wide disk of MA16 when cultivated on PDA medium for 5 days. Miliang-1 (A. deliciosa) and Hongyang (A. chinensis) plants were treated similarly. The control groups each included three plants that were inoculated with non-colonized PDA. The plants were kept at 25 °C with a 12-/12-h light/dark cycle for 10 days when the inoculated plants exhibited root rot symptoms similar to those seen in the field, together with rotting and browning of the leaves. The control plants appeared healthy with no symptoms. After re-isolated from infected tissues, the pathogen was verified to be G. spinosum according to its ITS sequence, thus fulfilling the Koch’s postulates. Recently, Pythium spinosum has been classified as G. spinosum according to whole-genome sequencing and phylogenomic analysis (Nguyen et al. 2022). Based on the morphological features and pathogenicity results, MA16 was identified as G. spinosum (van der Plaats-Niterink 1981; Huo et al. 2023). This report appears to be the first description of kiwifruit root rots caused by G. spinosum in China, and its identification will assist the development of strategies to counteract the disease.

Wood and engineered wood products are green construction materials with excellent mechanical properties, widely utilized in various buildings and bridges. This paper reviews their short-term and long-term mechanical properties and probabilistic models. Short-term mechanical properties analysis reveals strong tensile (up to 165 MPa) and bending strengths (up to 264 MPa), contrasted by lower compressive strength (up to 103 MPa) and minimal shear/rolling strength (up to 14 MPa). These properties vary based on species type, lay-up angle, and dimensions, and are mutually influential. It also demonstrated that innovative techniques such as compression and cross-laminated lay-ups enhance the strength and sustainability of wood products, utilizing smaller logs effectively and reducing carbon emissions. For long-term mechanical properties, empirical models typically used for creep strength assessment fail to account for load duration variability, a gap partly addressed by damage accumulation models which require further development. The considerable time for long-term tests underlines the need for developing accelerated load tests to more effectively assess durability. As for probabilistic models, numerical methods and machine learning provide advanced probabilistic models by analyzing extensive data, offering significant improvements over traditional experimental methods.The global contribution of the work is mainly to enhance the understanding of wood and engineered wood products for properly design and extensive application of timber structures in civil engineering and promoting sustainable development.

Timber structures have advantages such as green environmental protection and low-carbon energy conservation. Bolted connection with steel plate as one of the most commonly used dowel-type connections is widely used in timber structures. Nevertheless, the splitting capacity of timber beams loaded perpendicular to the grain by bolted connections with steel plate is influenced by various factors, leading to significant differences in calculation formulas and outcomes. On the basis of preliminary experimental research, a total of 113 timber beams and 6 bamboo glulam beams with steel plate bolted connections, loaded perpendicular to the grain, were tested and categorized into two main groups, with the consideration of the materials used for members and the total width of bolted connections. It was found that the splitting capacity of bolted connections loaded perpendicular to the grain increased along with the increase of material density of wood and bamboo. Essentially, a linear correlation was observed between the splitting capacity and the material density. In addition, the splitting capacity increased with an increase in the total width of connections and that the splitting capacity tended to be constant when the total width of connections reached a certain amount. Based on the test results and the current calculation model for splitting capacity, a modified model for calculating the splitting capacity of bolted connections loaded perpendicular to the grain was proposed. Notably, the average ratio of the calculated splitting capacity to literature-reported experimental results is 0.975. More importantly, the modified model, considering a comprehensive set of factors, offers broader application and improves usability for engineering designers.

Connections in timber beams loaded perpendicular to the wood grain are prone to brittle splitting failure. Different approaches can be found in the literature and design codes to account for the splitting capacity in the design of the structure. To study the splitting strength of timber beams loaded perpendicular to the wood grain by bolted steel-wood-steel connections, a total of 240 larch timber beams were tested. The impacts of the diameter of bolts, the number of bolts, the relative connection height, the beam span, and multiple connections of simply supported beams and continuous beams as well as the connection locations with respect to simply supported beams and overhanging beams on the splitting capacity, were investigated. Material properties such as the perpendicular-to-grain tensile strength, modulus of elasticity parallel to the wood grain, and Mode I fracture energy of the tested beams were also evaluated. Based on the comparisons between the test results and the predictions of different approaches for timber beams loaded perpendicular to the wood grain using bolted steel-wood-steel connections, the prediction ability of different approaches was analyzed and recommendations for the approach modification were given.

Differential concentrations of phytohormone trigger distinct outputs, which provides a mechanism for the plasticity of plant development and an adaptation strategy among plants to changing environments. However, the underlying mechanisms of the differential responses remain unclear. Here we report that a high concentration of auxin, distinct from the effect of low auxin concentration, enhances abscisic acid (ABA) responses in Arabidopsis thaliana, which partially relies on TRANS-MEMBERANE KINASE 1 (TMK1), a key regulator in auxin signaling. We show that high auxin and TMK1 play essential and positive roles in ABA signaling through regulating ABA INSENSITIVE 1 and 2 (ABI1/2), two negative regulators of the ABA pathway. TMK1 inhibits the phosphatase activity of ABI2 by direct phosphorylation of threonine 321 (T321), a conserved phosphorylation site in ABI2 proteins, whose phosphorylation status is important for both auxin and ABA responses. This TMK1-dependent auxin signaling in the regulation of ABA responses provides a possible mechanism underlying the high auxin responses in plants and an alternative mechanism involved in the coordination between auxin and ABA signaling.

Two distinct closterovirus-like genome sequences (termed AdV-1 v1 and v2) were identified in Actinidia chinensis var. deliciosa ‘Miliang-1’ that had no disease symptoms using high-throughput sequencing. Using overlapping reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends, the genomic sequences of AdV-1 v1 and v2 were confirmed as 17,646 and 18,578 nucleotides in length, respectively. The two complete genomes contained 9 and 15 open reading frames, respectively, coding for proteins having domains typical of Closteroviridae , such as RNA-dependent RNA polymerase (RdRp), heat shock protein 70 homolog (HSP70h) and coat protein (CP). Sequence analysis showed that the amino acid sequences of RdRp, HSP70h, and CP of the two variants exhibited high similarity (> 80%), while their genomic organization was somewhat different. This suggested that the two viral genomes identified here are variants of the family Closteroviridae in a single kiwifruit host. Furthermore, phylogenetic relationship analysis revealed that the two variants had a closer relationship with the unclassified virus Persimmon virus B (PeVB) and Actinidia virus 1 (AcV-1) than with other members of the family Closteroviridae , as did their genomic organization. It is speculated that the two variants, together with PeVB and AcV-1 belong to a new subfamily of Closteroviridae .

In scores of experiments indicates that the super-retarding mortar, keeping plasticity long-term, can make cement setting and hardening at a slower speed through chemical additive. Based on large numbers of orthogonal tests and theoretical analyses, the super-retarding mortar which satisfies the demands of actual engineering was developed successfully in present paper. And it is consist of cement, sand, water and composite retarder blended in an appropriate rate. From 0°C to 40°C, setting time can be adjusted from 1 day to 22 days in the light of to the engineering requirements, and after condensation, it begins to harden gradually and ends with the compression strengthen over 30MPa. Experiments were employed to test the influences of accession amounts of composite retarder dosage on setting time and compression strengthen of super-retarding mortar. Besides, the retarding mechanism was studied, and the super-retarding mortar was applied to experimental models. The results show the super-retarding mortar can be applied to the actual engineering, and it can be treated as the theoretical reference for the actual project application of the new prestressed concrete system.

Two different mRNA transcripts and their genomic sequence of Fe-Superoxide dismutase gene were obtained with homologous and RACE from embryogenic callus of an ancient litchi tree ‘ Songli',and the bioinformatics were analyzed to illustrate its role in the process of in vitro reservation.The full length of LcFeSOD cDNA was about 1 285 bp,containing a 753-nucleotides-long open reading frame(ORF) which encoding a protein of 250 amino acid residues,named as LcFe-SOD7a.Bioinformatics analysis showed that the protein encoded by LcFe-SOD7a with transmembrane helices was hydrophilic,stable and acidic protein,mainly located in the microbody(peroxisome) and cytoplasm,and had a variety of phosphorylation sites.The genomic sequence of LcFe-SOD7a with a length of 2 284 bp was consisted of seven introns,with the fourth intron 920 bp,the longest.Meanwhile,an intron kept alternative splicing gene,named LcFe-SOD7b,which encoding a protein of 207 amino acid residues was obtained,which causing protein encoding terminated in advance.