Upland rice genomic signatures of adaptation to drought resistance and navigation to molecular design breeding.

Upland rice is a distinctive drought-aerobic ecotype of cultivated rice highly resistant to drought stress. However, the genetic and genomic basis for the drought-aerobic adaptation of upland rice remains largely unclear due to the lack of genomic resources. In this study, we identified 25 typical upland rice accessions and assembled a high-quality genome of one of the typical upland rice varieties, IRAT109, comprising 384 Mb with a contig N50 of 19.6 Mb. Phylogenetic analysis revealed upland and lowland rice have distinct ecotype differentiation within the japonica subgroup. Comparative genomic analyses revealed that adaptive differentiation of lowland and upland rice is likely attributable to the natural variation of many genes in promoter regions, formation of specific genes in upland rice, and expansion of gene families. We revealed differentiated gene expression patterns in the leaves and roots of the two ecotypes and found that lignin synthesis mediated by the phenylpropane pathway plays an important role in the adaptive differentiation of upland and lowland rice. We identified 28 selective sweeps that occurred during domestication and validated that the qRT9 gene in selective regions can positively regulate drought resistance in rice. Eighty key genes closely associated with drought resistance were appraised for their appreciable potential in drought resistance breeding. Our study enhances the understanding of the adaptation of upland rice and provides a genome navigation map of drought resistance breeding, which will facilitate the breeding of drought-resistant rice and the "blue revolution" in agriculture.

Sodium alginate-modified alkali-activated eggshell/Fe3O4 nanoparticles: A magnetic bio-based spherical adsorbent for cationic dyes adsorption.

Herein, a mixture of eggshell (ES) and magnetite nanoparticles (MNPs) was alkali-activated using NaOH/Na2SiO3 solution and then, impregnated with sodium alginate (SA) to prepare a magnetic bio-based adsorbent (namely SAAES/SA/MNPs) for the decontamination of water containing basic dyes, in particular, methylene blue (MB) and crystal violet (CV). The physicochemical properties of magnetic spheres of SAAES/SA/MNPs were characterized using XRD, FTIR, FESEM, EDX, elemental mapping, TEM, and zeta potential techniques. Dye adsorption equilibrium was studied experimentally at pH 8.0 and 25-55 °C, and a statistical physics multilayer model was applied to understand the removal mechanism of these dyes including the adsorption orientations on the adsorbent surface. The number of adsorbed dye molecules per functional group (n) of this bio-based adsorbent ranged from 0.70 to 0.91, indicating the presence of vertical and horizontal adsorption orientations for these organic molecules at all tested solution temperatures. The calculated saturation adsorption capacities (Qsat) were 332.57-256.62 mg/g for CV and 304.47-240.62 mg/g for MB, and an exothermic adsorption was observed for both adsorbates. The estimated adsorption energies (∆E) were < 25 kJ/mol, confirming that the SAAES/SA/MNPs-dye interactions were governed by physical forces as electrostatic interactions. This bio-based adsorbent was effectively regenerated using ethanol and it can be reused showing a removal of 71 and 74 % of MB and CV, respectively, after fourth adsorption-desorption cycles. Overall, the results of this article suggest the attractive performance of SAAES/SA/MNPs for removing basic dyes from aqueous solutions, thus highlighting the promising potential of this magnetic bio-based adsorbent for sustainable wastewater treatment at an industrial level.

Changes in the soil fungal communities of steppe grasslands at varying degradation levels in North China.

The grasslands in North China are rich in fungal resources. However, the knowledge of the structure and function of fungal communities and the role of microbial communities in vegetation restoration and succession are limited. Thus, we used an Illumina HiSeq PE250 high-throughput sequencing platform to study the changing characteristics of soil fungal communities in degraded grasslands, which were categorized as non-degraded (ND), lightly degraded, moderately degraded, and severely degraded (SD). Moreover, a correlation analysis between soil physical and chemical properties and fungal communities was completed. The results showed that the number of plant species, vegetation coverage, aboveground biomass, and diversity index decreased significantly with increasing degradation, and there were significant differences in the physical and chemical properties of the soil among the different degraded grasslands. The dominant fungal phyla in the degraded grassland were as follows: Ascomycota, 44.88%-65.03%; Basidiomycota, 12.68%-29.91%; and unclassified, 5.51%-16.91%. The dominant fungi were as follows: Mortierella, 6.50%-11.41%; Chaetomium, 6.71%-11.58%; others, 25.95%-36.14%; and unclassified, 25.56%-53.0%. There were significant differences in the microbial Shannon-Wiener and Chao1 indices between the ND and degraded meadows, and the composition and diversity of the soil fungal community differed significantly as the meadows continued to deteriorate. The results showed that pH was the most critical factor affecting soil microbial and fungal communities in SD grasslands, whereas soil microbial and fungal communities in ND grasslands were mainly affected by water content and other environmental factors.

Geographic differences and variation of functional components of brown rice in 690 mini-core collections from global germplasms.

Objective: To understand the geographic differences and variations in the functional components of brown rice cores collected from global rice germplasms. Methods: Four functional components, γ-aminobutyric acid (GABA), resistant starch (RS), total flavonoids, and alkaloids, in brown rice from 690 mini-core collections from 31 countries from five continents and the International Rice Research Institute, were analyzed using a spectrophotometry colorimetric method, and the results were statistically validated. Conclusion: The highest average amounts of functional components were obtained in Asian germplasms, except for GABA, and total flavonoids were highest in brown rice from Europe and Oceania, followed by Asia. The highest coefficient of variation for GABA was observed in Asia; that for RS and total flavonoids was observed in Africa, followed by Asia; and that for alkaloids was observed in America, followed by Asia. Overall, Asian countries were the most prominent and representative zones with the highest genotypic potential for functional components of brown rice. Forty-one rice accessions with enriched functional components originated mostly from biodiversity-rich areas in China, followed by those in the Philippines. Late sowing favored the enrichment of these components in brown rice. The current study provides a reference for rice breeding with enriched functional constituents, and guidelines for screening functional rice that could be used for human chronic disease research.

Effect of Air Pollutants and Meteorological Factors on Daily Outpatient Visits of Allergic Rhinitis in Hohhot, China.

Objective: There is limited evidence that atmospheric pollutants are associated with the number of allergic rhinitis (AR) visits. This study aimed to investigate the relationship between atmospheric pollutants and meteorological factors and the number of daily visits for AR in Hohhot City, providing a theoretical basis for further research on the effects of atmospheric pollutants on AR. Methods: Microsoft Excel 2016 was used to collect and organize the AR outpatient consultation data, air pollution and meteorological data in Hohhot City during 2018-2020, and the data were descriptively analyzed and Spearman correlation test was performed using SPSS22.0; A generalized additive model was built in R4.2.3 to analyze the effect of air pollution on the number of AR visits and its lagged and cumulative effects, while the robustness of the model was tested using a two-pollutant analysis. Finally, we analyzed the effects of the interaction of temperature, relative humidity and pollutants on the number of AR visits. Results: The daily average concentrations of PM2.5, PM10, SO2, NO2, CO, and O3 in Hohhot during 2018-2020 were 38.1 µg/m3, 83.3 µg/m3, 36.1 µg/m3, 15.1 µg/m3, 14.2 mg/m3, and 99.95 µg/m3, respectively, with the concentrations of PM2.5 and PM10 exceeding the secondary limit of the national standard. The results of the generalized additive model analysis showed that the RR and 95% CI of the effect of each 10 µg/m3 increase in pollutant concentration (1 mg/m3 increase in CO) on the number of AR outpatient clinics were 1.008 (1.001-1.016), 1.002 (1-1.005), 1.072 (1.033-1.113), 1.020 (1007-1.034), 1.033 (1.014-1.052), 0.987 (0.9804-0.9936). Conclusion: Short-term exposure to PM2.5, PM10, SO2, NO2, and CO was significantly associated with an increase in AR clinic visits, and short-term exposure to O3 was significantly associated with a decrease in allergic rhinitis clinic visits.

Relationship Between Outdoor Air Pollutant Exposure and Premature Delivery in China- Systematic Review and Meta-Analysis.

Objective: Preterm birth (PTB) is considered as a public health problem and one of the main risk factors related to the global disease burden. The purpose of this study aims to explore the influence of exposure to major air pollutants at different pregnancies on PTB. Methods: The relationship between air pollutants and PTB in China was collected from cohort studies and case-control studies published before 30 April 2022. Meta-analysis was carried out with STATA 15.0 software. Results: A total of 2,115 papers were retrieved, of which 18 papers met the inclusion criteria. The comprehensive effect of pollutant exposure and PTB were calculated. PM2.5 during entire pregnancy and O3 exposure during third trimester were positively associated with preterm birth. Every 10 µg/m3 increase in the average concentration of PM2.5 during the whole pregnancy will increase the risk of premature delivery by 4%, and every 10 µg/m3 increase in the average concentration of O3 in the third trimester will increase the risk of premature delivery by 1%. Conclusion: Exposure to PM2.5 entire prenatal pregnancy and O3 in third trimester is associated with an increased risk of preterm birth occurrence.

Genome-Wide Association Study Reveals the Genetic Basis of Total Flavonoid Content in Brown Rice.

Flavonoids have anti-inflammatory, antioxidative, and anticarcinogenic effects. Breeding rice varieties rich in flavonoids can prevent chronic diseases such as cancer and cardio-cerebrovascular diseases. However, most of the genes reported are known to regulate flavonoid content in leaves or seedlings. To further elucidate the genetic basis of flavonoid content in rice grains and identify germplasm rich in flavonoids in grains, a set of rice core collections containing 633 accessions from 32 countries was used to determine total flavonoid content (TFC) in brown rice. We identified ten excellent germplasms with TFC exceeding 300 mg/100 g. Using a compressed mixed linear model, a total of 53 quantitative trait loci (QTLs) were detected through a genome-wide association study (GWAS). By combining linkage disequilibrium (LD) analysis, location of significant single nucleotide polymorphisms (SNPs), gene expression, and haplotype analysis, eight candidate genes were identified from two important QTLs (qTFC1-6 and qTFC9-7), among which LOC_Os01g59440 and LOC_Os09g24260 are the most likely candidate genes. We also analyzed the geographic distribution and breeding utilization of favorable haplotypes of the two genes. Our findings provide insights into the genetic basis of TFC in brown rice and could facilitate the breeding of flavonoid-rich varieties, which may be a prevention and adjuvant treatment for cancer and cardio-cerebrovascular diseases.

Genetic-based dissection of resistance to bacterial leaf streak in rice by GWAS.

BACKGROUND: Rice is the second-largest food crop in the world and vulnerable to bacterial leaf streak disease. A thorough comprehension of the genetic foundation of agronomic traits was essential for effective implementation of molecular marker-assisted selection. RESULTS: Our study aimed to evaluate the vulnerability of rice to bacterial leaf streak disease (BLS) induced by the gram-negative bacterium Xanthomonas oryzae pv. oryzicola (Xoc). In order to accomplish this, we first analyzed the population structure of 747 accessions and subsequently assessed their phenotypes 20 days after inoculation with a strain of Xoc, GX01. We conducted genome-wide association studies (GWAS) on a population of 747 rice accessions, consisting of both indica and japonica subpopulations, utilizing phenotypic data on resistance to bacterial leaf streak (RBLS) and sequence data. We identified a total of 20 QTLs associated with RBLS in our analysis. Through the integration of linkage mapping, sequence analysis, haplotype analysis, and transcriptome analysis, we were able to identify five potential candidate genes (OsRBLS1-OsRBLS5) that possess the potential to regulate RBLS in rice. In order to gain a more comprehensive understanding of the genetic mechanism behind resistance to bacterial leaf streak, we conducted tests on these genes in both the indica and japonica subpopulations, ultimately identifying superior haplotypes that suggest the potential utilization of these genes in breeding disease-resistant rice varieties. CONCLUSIONS: The findings of our study broaden our comprehension of the genetic mechanisms underlying RBLS in rice and offer significant insights that can be applied towards genetic improvement and breeding of disease-resistant rice in rapidly evolving environmental conditions.

Highly flame-retardant materials of different divalent metal ions alginate/silver phosphate: Synthesis, characterizations, and synergistic phosphorus-polymetallic effects.

Three kinds of divalent metal ions (Ca2+, Cu2+, Zn2+) alginate/silver phosphate (MAlg/Ag3PO4) hybrid materials were prepared via an in-situ method, and the composites were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infrared spectrum (FTIR). To investigate their flame-retardant properties and phosphorus-polymetallic flame-retardant effects, the combustion behavior and flammability of the composites were assessed by using the thermogravimetric analysis (TGA), limiting oxygen index (LOI) and micro-calorimeter tests (MCC). The results show that the three composites were thermally stable, among which the LOI of CaAlg/Ag3PO4, CuAlg/Ag3PO4 and ZnAlg/Ag3PO4 were 62.6 %, 46.5 % and 79.8 %, respectively, which were much higher than the prescribed flame retardants which was 27 %. According to the TGA, the thermal stability was ZnAlg/Ag3PO4 > CaAlg/Ag3PO4 > CuAlg/Ag3PO4. The heat release capacity (HRC) of the above three materials was 49 J/(g·K), 69 J/(g·K), 41 J/(g·K), respectively, and the fire safety performance was also in the same order as the thermal stability. By using the thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS), the flame retarding mechanism of MAlg/Ag3PO4 and the synergistic effect of Ag3PO4 and divalent metal ions were proposed based on the experimental data.

The synergistic hydration mechanism and environmental safety of multiple solid wastes in red mud-based cementitious materials.

Red mud (RM) is a solid waste material with high alkalinity and low cementing activity component. The low activity of RM makes it difficult to prepare high-performance cementitious materials from RM alone. Five groups of RM-based cementitious samples were prepared by adding steel slag (SS), grade 42.5 ordinary Portland cement (OPC), blast furnace slag cement (BFSC), flue gas desulfurization gypsum (FGDG), and fly ash (FA). The effects of different solid waste additives on the hydration mechanisms, mechanical properties, and environmental safety of RM-based cementitious materials were discussed and analyzed. The results showed that the samples prepared from different solid waste materials and RM formed similar hydration products, and the main products were C-S-H, tobermorite, and Ca(OH)2. The mechanical properties of the samples met the single flexural strength criterion (≥ 3.0 MPa) for first-grade pavement brick in the Industry Standard of Building Materials of the People's Republic of China-Concrete Pavement Brick. The alkali substances in the samples existed stably, and the leaching concentrations of the heavy metals reached class III of the surface water environmental quality standards. The radioactivity level was in the unrestricted range for main building materials and decorative materials. The results manifest that RM-based cementitious materials have the characteristics of environmentally friendly materials and possess the potential to partially or fully replace traditional cement in the development of engineering and construction applications and it provides innovative guidance for combined utilization of multi-solid waste materials and RM resources.

B20 Weyl Semimetal CoSi Film Fabricated by Flash-Lamp Annealing.

B20-CoSi is a newly discovered Weyl semimetal that crystallizes into a noncentrosymmetric crystal structure. However, the investigation of B20-CoSi has so far been focused on bulk materials, whereas the growth of thin films on technology-relevant substrates is a prerequisite for most practical applications. In this study, we have used millisecond-range flash-lamp annealing, a nonequilibrium solid-state reaction, to grow B20-CoSi thin films. By optimizing the annealing parameters, we were able to obtain thin films with a pure B20-CoSi phase. The magnetic and transport measurements indicate the appearance of the charge density wave and chiral anomaly. Our work presents a promising method for preparing thin films of most binary B20 transition-metal silicides, which are candidates for topological Weyl semimetals.

Dual-functional marine algal carbon-based materials with highly efficient dye removal and disinfection control.

The design and simple, green preparation of dual-functional materials for the decontamination of both hazardous dyes and pathogenic microorganisms from wastewater remain challenging currently. Herein, a promising marine algal carbon-based material (named C-SA/SP) with both highly efficient dye adsorptive and antibacterial properties was fabricated based on the incorporation of sodium alginate and a low dose of silver phosphate via a facile and eco-friendly approach. The structure, removal of malachite green (MG) and congo red (CR), and their antibacterial performance were studied, and the adsorption mechanism was further interpreted by the statistical physics models, besides the classic models. The results show that the maximum simulated adsorption capacity for MG reached 2798.27 mg/g, and its minimal inhibit concentration for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 0.4 mg/mL and 0.2 mg/mL, respectively. The mechanistic study suggests that silver phosphate exerted the effects of catalytic carbon formation and pore formation, while reducing the electronegativity of the material as well, thus improving its dye adsorptive performance. Moreover, the MG adsorption onto C-SA/SP showed vertical orientation and a multi-molecular way, and its adsorption sites were involved in the adsorption process with the increase of temperature. Overall, the study indicates that the as-made dual-functional materials have good applied prospects for water remediation.

Study on hydration mechanism and environmental safety of thermal activated red mud-based cementitious materials.

Red mud (RM) cementitious materials were prepared with the thermally, thermoalkali- or thermocalcium-activated RM, steel slag (SS), and other additives. The effects of different thermal RM activation methods on the cementitious material hydration mechanisms, mechanical properties, and environmental risks were discussed and analyzed. The results showed that the hydration products of different thermally activated RM samples were similar with the main products being C-S-H, tobermorite, and Ca(OH)2. Ca(OH)2 was mainly present in thermally activated RM samples, and the tobermorite was mainly produced by samples prepared with thermoalkali- and the thermocalcium-activated RM. The mechanical properties of the samples prepared by thermally and thermocalcium-activated RM had early-strength properties, while the thermoalkali-activated RM samples were similar to the late-strength type of cement properties. The average flexural strength of thermally and the thermocalcium-activated RM samples at 14 days were 3.75 MPa and 3.87 MPa respectively, whereas, the 1000 °C thermoalkali-activated RM samples only at 28 days was 3.26 MPa; the above data could reach the single flexural strength (3.0 MPa) of the first-grade pavement blocks of the building materials industry standard of the People's Republic of China-concrete pavement blocks (JC/T446-2000). The optimal preactivated temperature for different thermally activated RM was different; the optimal preactivated temperature for both thermally and thermocalcium-activated RM was 900 °C, and the flexural strength was 4.46 MPa and 4.35 MPa, respectively. However, the optimal preactivated temperature of thermoalkali activated RM at 1000 °C. The 900 °C thermally activated RM samples had better solidified effects for heavy metal elements and alkali substances. 600~800℃ thermoalkali activated RM samples had better solidified effects for heavy metal elements. Different temperatures of thermocalcium-activated RM samples showed different solidified effects on different heavy metal elements, which may be due to the influence of thermocalcium activation temperature on the structural changes of the hydration products of the cementitious samples. In this study, three thermal RM activation methods were proposed, and the co-hydration mechanism and environmental risk study of different thermally activated RM and SS were further elucidated. This not only provides an effective method for the pretreatment and safe utilization of RM, but also facilitates the synergistic resource treatment of solid waste and further promotes the research process of replacing part of traditional cement with solid waste.

RRS1 shapes robust root system to enhance drought resistance in rice.

A strong root system facilitates the absorption of water and nutrients from the soil, to improve the growth of crops. However, to date, there are still very few root development regulatory genes that can be used in crop breeding for agriculture. In this study, we cloned a negative regulator gene of root development, Robust Root System 1 (RRS1), which encodes an R2R3-type MYB family transcription factor. RRS1 knockout plants showed enhanced root growth, including longer root length, longer lateral root length, and larger lateral root density. RRS1 represses root development by directly activating the expression of OsIAA3 which is involved in the auxin signaling pathway. A natural variation in the coding region of RRS1 changes the transcriptional activity of its protein. RRS1T allele, originating from wild rice, possibly increases root length by means of weakening regulation of OsIAA3. Knockout of RRS1 enhances drought resistance by promoting water absorption and improving water use efficiency. This study provides a new gene resource for improving root systems and cultivating drought-resistant rice varieties with important values in agricultural applications.

Semiconducting Conjugated Coordination Polymer with High Charge Mobility Enabled by "4 + 2" Phenyl Ligands.

Electrically conductive coordination polymers and metal-organic frameworks are attractive emerging electroactive materials for (opto-)electronics. However, developing semiconducting coordination polymers with high charge carrier mobility for devices remains a major challenge, urgently requiring the rational design of ligands and topological networks with desired electronic structures. Herein, we demonstrate a strategy for synthesizing high-mobility semiconducting conjugated coordination polymers (c-CPs) utilizing novel conjugated ligands with D2h symmetry, namely, "4 + 2" phenyl ligands. Compared with the conventional phenyl ligands with C6h symmetry, the reduced symmetry of the "4 + 2" ligands leads to anisotropic coordination in the formation of c-CPs. Consequently, we successfully achieve a single-crystalline three-dimensional (3D) c-CP Cu4DHTTB (DHTTB = 2,5-dihydroxy-1,3,4,6-tetrathiolbenzene), containing orthogonal ribbon-like π-d conjugated chains rather than 2D conjugated layers. DFT calculation suggests that the resulting Cu4DHTTB exhibits a small band gap (∼0.2 eV), strongly dispersive energy bands near the Fermi level with a low electron-hole reduced effective mass (∼0.2m0*). Furthermore, the four-probe method reveals a semiconducting behavior with a decent conductivity of 0.2 S/cm. Thermopower measurement suggests that it is a p-type semiconductor. Ultrafast terahertz photoconductivity measurements confirm Cu4DHTTB's semiconducting nature and demonstrate the Drude-type transport with high charge carrier mobilities up to 88 ± 15 cm2 V-1 s-1, outperforming the conductive 3D coordination polymers reported till date. This molecular design strategy for constructing high-mobility semiconducting c-CPs lays the foundation for achieving high-performance c-CP-based (opto-)electronics.

Natural variation in Tiller Number 1 affects its interaction with TIF1 to regulate tillering in rice.

Tiller number per plant-a cardinal component of ideal plant architecture-affects grain yield potential. Thus, alleles positively affecting tillering must be mined to promote genetic improvement. Here, we report a Tiller Number 1 (TN1) protein harbouring a bromo-adjacent homology domain and RNA recognition motifs, identified through genome-wide association study of tiller numbers. Natural variation in TN1 affects its interaction with TIF1 (TN1 interaction factor 1) to affect DWARF14 expression and negatively regulate tiller number in rice. Further analysis of variations in TN1 among indica genotypes according to geographical distribution revealed that low-tillering varieties with TN1-hapL are concentrated in Southeast Asia and East Asia, whereas high-tillering varieties with TN1-hapH are concentrated in South Asia. Taken together, these results indicate that TN1 is a tillering regulatory factor whose alleles present apparent preferential utilization across geographical regions. Our findings advance the molecular understanding of tiller development.

Variations in OsSPL10 confer drought tolerance by directly regulating OsNAC2 expression and ROS production in rice.

Drought is a major factor restricting the production of rice (Oryza sativa L.). The identification of natural variants for drought stress-related genes is an important step toward developing genetically improved rice varieties. Here, we characterized a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) family, OsSPL10, as a transcription factor involved in the regulation of drought tolerance in rice. OsSPL10 appears to play a vital role in drought tolerance by controlling reactive oxygen species (ROS) production and stomatal movements. Haplotype and allele frequency analyses of OsSPL10 indicated that most upland rice and improved lowland rice varieties harbor the OsSPL10Hap1 allele, whereas the OsSPL10Hap2 allele was mainly present in lowland and landrace rice varieties. Importantly, we demonstrated that the varieties with the OsSPL10Hap1 allele showed low expression levels of OsSPL10 and its downstream gene, OsNAC2, which decreases the expression of OsAP37 and increases the expression of OsCOX11, thus preventing ROS accumulation and programmed cell death (PCD). Furthermore, the knockdown or knockout of OsSPL10 induced fast stomatal closure and prevented water loss, thereby improving drought tolerance in rice. Based on these observations, we propose that OsSPL10 confers drought tolerance by regulating OsNAC2 expression and that OsSPL10Hap1 could be a valuable haplotype for the genetic improvement of drought tolerance in rice.

Large-scale genomic and transcriptomic profiles of rice hybrids reveal a core mechanism underlying heterosis.

BACKGROUND: Heterosis is widely used in agriculture. However, its molecular mechanisms are still unclear in plants. Here, we develop, sequence, and record the phenotypes of 418 hybrids from crosses between two testers and 265 rice varieties from a mini-core collection. RESULTS: Phenotypic analysis shows that heterosis is dependent on genetic backgrounds and environments. By genome-wide association study of 418 hybrids and their parents, we find that nonadditive QTLs are the main genetic contributors to heterosis. We show that nonadditive QTLs are more sensitive to the genetic background and environment than additive ones. Further simulations and experimental analysis support a novel mechanism, homo-insufficiency under insufficient background (HoIIB), underlying heterosis. We propose heterosis in most cases is not due to heterozygote advantage but homozygote disadvantage under the insufficient genetic background. CONCLUSION: The HoIIB model elucidates that genetic background insufficiency is the intrinsic mechanism of background dependence, and also the core mechanism of nonadditive effects and heterosis. This model can explain most known hypotheses and phenomena about heterosis, and thus provides a novel theory for hybrid rice breeding in future.

Precise tuning of interlayer electronic coupling in layered conductive metal-organic frameworks.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have attracted increasing interests for (opto)-electronics and spintronics. They generally consist of van der Waals stacked layers and exhibit layer-depended electronic properties. While considerable efforts have been made to regulate the charge transport within a layer, precise control of electronic coupling between layers has not yet been achieved. Herein, we report a strategy to precisely tune interlayer charge transport in 2D c-MOFs via side-chain induced control of the layer spacing. We design hexaiminotriindole ligands allowing programmed functionalization with tailored alkyl chains (HATI_CX, X = 1,3,4; X refers to the carbon numbers of the alkyl chains) for the synthesis of semiconducting Ni3(HATI_CX)2. The layer spacing of these MOFs can be precisely varied from 3.40 to 3.70 Å, leading to widened band gap, suppressed carrier mobilities, and significant improvement of the Seebeck coefficient. With this demonstration, we further achieve a record-high thermoelectric power factor of 68 ± 3 nW m-1 K-2 in Ni3(HATI_C3)2, superior to the reported holes-dominated MOFs.

A population-based cohort study for presence of ulceration among cutaneous malignant melanoma subgroups of patients.

Background: Observational studies suggest that ulceration is considered to be a negative prognostic factor for cutaneous melanoma. However, the impact of ulceration over different subgroups (e.g. AJCC Stage, thickness level) are controversial and its true causal effect on survival is lack of studies in the view of treating ulceration as an exposure. Objective: To explore the true causal effect of ulceration on melanoma's survival by adopting a combination of methods to discover proper adjustment set and confirming its correctness through a variety of means. Methods: A minimal sufficient adjustment set (MSAS) was found using directed acyclic graphs (DAG) to adjust the effect of causality. Sensitivity analysis was conducted to diagnose potential confounders in addition to MSAS. Cox models were built to analyze the causality in-depth and the model was validated using a novel method. Lastly, stratified effects of ulceration were examined to illustrate its impact within subgroups. Results: Hazard ratio (HR) of ulceration after adjustment by MSAS variables was 1.99 (95% CI=1.88-2.09). The sensitivity analysis of propensity score matching and E-value both demonstrated that variables other than MSAS do not have great influence on ulceration and MSS relationship. The HR of ulceration in AJCC Stage, thickness level, invasion level and tumor extension were all monotonically decreased from 5.76 to 1.57, 4.03 to 1.78, 2.75 to 1.78 and 2.65 to 1.71 respectively. Conclusion: Ulceration in all subgroups were shown to have a significantly negative impact on MSS and its magnitude of effect was monotonically decreased as the disease progressed. The true effect of ulceration can be adjusted by MSAS and its correctness was validated through a variety of approaches.