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Cytidine base editor (CBE), which is composed of a cytidine deaminase fused to Cas9 nickase, has been widely used to induce C-to-T conversions in a wide range of organisms. However, the targeting scope of current CBEs is largely restricted to protospacer adjacent motif (PAM) sequences containing G, T, or A bases. In this study, we developed a new base editor termed “nNme2-CBE” with excellent PAM compatibility for cytidine dinucleotide, significantly expanding the genome-targeting scope of CBEs. Using nNme2-CBE, targeted editing efficiencies of 29.0%–55.0% and 17.3%–52.5% were generated in human cells and rabbit embryos, respectively. In contrast to conventional nSp-CBE, the nNme2-CBE is a natural high-fidelity base editing platform with minimal DNA off-targeting detected in vivo . Significantly increased efficiency in GC context and precision were determined by combining nNme2Cas9 with rationally engineered cytidine deaminases. In addition, the Founder rabbits with accurate single-base substitutions at Fgf5 gene loci were successfully generated by using the nNme2-CBE system. These novel nNme2-CBEs with expanded PAM compatibility and high fidelity will expand the base editing toolset for efficient gene modification and therapeutic applications.

Escherichia coli (E. coli) is one of the common pathogenic bacteria in veterinary clinical infection. As an opportunistic microorganism, E. coli normally does not cause diseases. However, it causes infections under certain circumstance to domesticated animal and poultry, resulting in severe diarrhea, septicemia, and respiratory infections. Although there are increasing reports regarding the infections of E. coli to domestic animals and poultry, the infection of E. coli in dogs is relatively less reported, especially on septicemia and meningoencephalitis. Here, we reported the isolation and identification of an E. coli isolate named CEC-GZL17 from dogs characterized by septicemia and sudden death, and found that CEC-GZL17 is able to cause meningoencephalitis. Exploration on the potential mechanism underlying meningoencephalitis demonstrated that CEC-GZL17 infection significantly increases TNF-α expression and inhibits ZO-1 and occludin expressions in brain tissue, indicating that the E coli likely use the mechanism to penetrate the blood-brain barrier via disrupting tight junction architecture, thus leading to the invasion to brain tissue.

Recently, a rationally engineered SpCas9 variant (SpCas9-NG) that can recognize a minimal NG protospacer adjacent motif (PAM) was reported to expand the targeting scope in genome editing. However, increased genome-wide off-target mutations with this variant compared with SpCas9 were reported in previous studies. In addition, lower base editing frequencies and higher unintended off-target mutations were also found in Hoxc13-ablated rabbits generated by NG-BE4max in our study. Here, a high-fidelity base editor, NG-HiFi, in comparison to NG-BE4max, showed retention of on-target activity while exhibiting significantly decreased off-target activity in Hoxc13-ablated rabbits. Collectively, the improved specificity and reduced off-target effect of SpCas9-NG assisted in cytidine base editing with the NG-HiFi system, providing a promising tool to precisely model human diseases in rabbits., Graphical abstract, NG-BE4max that can recognize NG PAM was reported to expand the targeting space in genome editing but, however, with higher genome-wide off-target mutations compared with BE4max. Here, a high-fidelity base editor, NG-HiFi, reduces the off-target effect, which is comparable to NG-BE4max.

BackgroundCytidine base editors (CBEs), composed of a cytidine deaminase fused to Cas9 nickase (nCas9), enable efficient C-to-T conversion in various organisms. However, current base editors can induce unwanted bystander C-to-T conversions when multiple Cs are present in the ~ 5-nucleotide activity window of cytidine deaminase, which negatively affects their precision. Here, we develop a new base editor which significantly reduces unwanted bystander activities.ResultsWe used an engineered human APOBEC3G (eA3G) C-terminal catalytic domain with preferential cytidine-deaminase activity in motifs with a hierarchy CCC>CCC>CC(where the preferentially deaminated C is underlined), to develop an eA3G-BE with distinctive CCcontext-specificity and reduced generation of bystander mutations. Targeted editing efficiencies of 18.3–58.0% and 54.5–92.2% with excellent CCcontext-specificity were generated in human cells and rabbit embryos, respectively. In addition, a base editor that can further recognize relaxed NG PAMs is achieved by combining hA3G with an engineered SpCas9-NG variant. The A3G-BEs were used to induce accurate single-base substitutions which led to nonsense mutation with an efficiency of 83–100% and few bystander mutations in Founder (F0) rabbits atTyrloci.ConclusionsThese novel base editors with improved precision and CCcontext-specificity will expand the toolset for precise gene modification in organisms.

Additional file 1: Figure S1. Immunoblots of the rA1-BEs and eA3G-BEs. Figure S2. Comparison of base editing frequencies in non-CC contexts with rA1-BE and eA3G-BE. Figure S3. Comparison of base editing frequencies at on- and off-target sites with rA1-BE and eA3G-BE. Figure S4. Comparison of base editing activity and precision using eA3G-BE and other precise BEs. Figure S5. Representative sequencing chromatograms of off-target detection in Tyr-1 and Tyr-4 mutant rabbits. Figure S6. Comparison of base editing frequencies between rA1-NG and eA3G-NG at 8 target sites with all NGN PAMs. Figure S7. Comparison of base editing activity using loop3 and loop 7 grafted eA3G-BEs. Table S1. Primers used for site-directed mutation in this study. Table S2. Primers used for genotyping in this study. Supplementary sequence. Amino acid sequence of eA3G-BE.

Cytidine base editors, composed of a cytidine deaminase fused to Cas9 nickase, enable efficient C-to-T conversion in various organisms. However, current base editors suffer from severe trade-off between editing efficiency and precision. Here, based on rationally mutated cytidine deaminase domain, we develop a new base editor, YFE-BE4max, effectively narrow the editing width to as little as approximately three nucleotides while maintaining high efficiency in rabbits. Moreover, YFE-BE4max successfully mediated the Tyr p. Q68Stop and Lmna p. G607G mutation in F0 rabbit with high efficiency and precision, which precisely recapitulates the pathological features of human OCA1 and HGPS, respectively. Collectively, YFE-BE4max system provide promising tools to perform efficient base editing with high precision in rabbits and enhances its capacity to precisely model human diseases.

Layered double hydroxides (LDHs), as one type of typical 2D inorganic layered materials, have been extensively used in drug loading and release, functional additive, adsorption, catalysis, energy storage, photochemistry and other fields, owing to their tunable interlayer space, good anisotropy and thermal stability. However, the application of LDHs powder normally suffers from mass losing and serious aggregation. Recent years, LDHs-based flexible composite films have shown promising application prospect in the field of electrochemical storage, optoelectronic devices, and gas barrier materials, due to their portability, ductility and good mechanical properties. This review introduced the preparation methods and application fields of LDHs-based flexible films and pointed out the future research directions.

A series of polyvinylidene fluoride (PVDF)/layered double hydroxide (LDH) composite membranes were prepared via phase inversion method, in which the presence of LDH promotes the formation of β-phase PVDF. This work reveals the key role of hydrogen-bonds on the nucleation mechanism and crystallization behavior of PVDF. The composite membranes exhibit improved porosity and hydrophilicity, leading to an enhanced antifouling property against proteins.

Poly(ethylene terephthalate) (PET) generally suffers from low crystallization rate and long molding duration, which as a result limit its application as engineering plastics. To overcome these drawbacks, series of PET/layered double hydroxide (LDH) nanocomposites were prepared by a solution blending process. The effect of metal composition (MgAl and CaAl) and organo-modification (stearic acid intercalated) for LDH fillers on the crystallization behavior of the nanocomposites was investigated. It was revealed that, compared with PET/CaAl-LDH, the PET/MgAl-LDH nanocomposite exhibits a higher crystallization temperature and faster crystallization rate, which is associated with the superior nucleation ability of MgAl-LDH. The nucleation mechanism of PET induced by LDHs was explored by means of Avrami equation and theory of Hoffman-Lauritzen, pointing out that the incorporation of LDHs reduce the free energy of nucleation and the fold surface free energy of PET. In order to improve the compatibility between LDH and PET, stearic acid (SA) intercalated MgAl-LDH was prepared and filled into PET matrix. The resultant PET/MgAl-LDH-SA shows a further enhanced crystallization temperature and accelerated crystallization rate, in comparison with PET/MgAl-LDH nanocomposites. In addition, the thermal stability, gas barrier and mechanical properties of PET/LDH composites were improved upon incorporation of LDH fillers.

Various shape memory alloy (SMA) dampers have been developed to reduce structural vibration responses. However, the application of SMA dampers has been restricted by the high material costs of SMAs. Therefore, this study developed and tested an innovative SMA damping inerter (SDI) in which an SMA element and an inerter element were arranged in parallel and deployed in series with a supporting spring element. A single-degree-of-freedom structure with an SDI was employed to analyze the effect of vibration mitigation. A theoretical analysis was conducted via an equivalent linearization method, and parameter studies were then used to evaluate the performance of the SDI-fitted structure from perspectives of structural displacement, acceleration, and energy dissipation as well as the most efficient frequency tuning bandwidth. The performances of the SDI and a conventional SMA damper were compared by using a time-domain analysis with recorded and simulated ground motions, revealing clearly superior results for the SDI with respect to structural response mitigation, and seismic energy dissipation. The system proposed here takes advantage of the full potential of combining SMA and inerter elements, making the SDI a robust system for mitigating structural vibration with more economical SMA material costs.

Layered double hydroxide (LDH) platelets with nanosized and microsized level were synthesized and used as fillers in an isotactic polypropylene (PP) matrix. The nucleation and crystallization behavior of PP/LDH composites (denoted as 1-PPLx and 2-PPLx for composites containing nanosized and microsized LDH, respectively; x represents the mass percentage of LDH) was investigated by differential scanning calorimetry and polarized optical microscopy techniques. It is found that the crystallization temperature of PP/LDH composites is largely enhanced and the half crystallization time is reduced remarkably relative to pure PP, especially for 2-PPLx composite. The 2-PPLx composite exhibits stronger heterogeneous nucleating ability and faster crystallization rate than 1-PPLx samples with the same LDH loading. In addition, the crystallized PP/LDH composites possess significantly enhanced thermal stability, gas barrier, and flame-retardant properties relative to neat PP, which would show a broad application prospect in engineering plastics and packing industry.

In this paper, an APP for building indoor environment evaluation and energy consumption estimation based on Android platform is proposed and established. While using the APP, the smart phone built-in sensors are called for real-time monitoring of the building environmental information such as temperature, humidity and noise, etc. the built-in algorithm is developed to calculate the heat and power consumption, and questionnaires, grading and other methods are used to feed back to the space heating system. In addition, with the application of the technology of big data and cloud technology, the data collected by users will be uploaded to the cloud. After the statistics of the uploaded data, regional difference can be obtained, thus providing a more accurate basis for macro-control and research of energy, thermal comfort, greenhouse effect.

This article presents a timely review of thermomechanical behaviours, recent structural applications, and researches of shape memory alloys (SMAs) in civil engineering. SMAs are used in a variety of fields, such as mechanical, aeronautical and medical fields. Other fields of knowledge have been researching these materials, attracted by their superb shape memory effect and pseudoelasticity under mechanical and thermal conditions. This article not only reports a bibliographic review on the constitutive models and thermodynamic properties for SMAs, but also describes the attributes of SMAs that make them ideally suitable to structural control, intelligent structure and structural damage repair.

The 4,5-dihydro-1,2,4-triazole Schiff base derivatives were synthesized with 4-amino-4,5-dihydro-3-(phenoxy- methyl)-1H-1,2,4-triazole-5-thione and substituted benzaldehydes. The chemical structures of the compounds have been confirmed by 1H NMR, IR spectra and elemental analysis. Their biological activities were investigated, and the results showed that they exhibited good fungicidal activities.

Eight Schiff bases of 3-amino-1H-1,2,4-triazole have been synthesized by glacial acetic acid catalyzed condensation of 3-amino-1H-1,2,4-triazole with substituted benzaldehyde and structurally confirmed by IR, 1H NMR and elemental analysis. The preliminary bioassay showed that the title compounds exhibited good fungicidal activities.

Eight Schiff bases have been synthesized using 3-alkyl-4-amino-1,2,4-triazole-5-thione and substituted benzaldehyde as starting materials. The structures of the compounds have been confirmed by 1H NMR, IR and elemental analysis and their biological activities to five vegetable pathogens have been tested. The results showed that they exhibited good fungicidal activities.

Seven pyrimethanil salts were synthesized by organic base containing nitrogen atom reacting with substituted pyridine acids. They are reported for the first time. Their structures have been confirmed by IR, 1H NMR and elemental analysis. The preliminary toxicity tests indicated that most of them exhibited excellent fungicidal activities. The relationship between the structures and the fungicidal activities of the compounds was discussed.

The low-temperature heat capacities of myclobutanil (C15H17CIN4) were precisely measured with an automated adiabatic calorimeter over the temperature range from 78 to 368 K. The sample was observed to melt at (348.800 +/- 0.06) K. The molar enthalpy and entropy of the melting as well as the chemical purity of the substance were determined to be Delta(fus)H(m) = (30931 +/- 11) J.mol(-1), Delta(fus)S(m) = (88.47 +/- 0.02) J.mol(-1).K-1 and 99.41%, respectively. Further research of the melting process for this compound was carried out by means of DSC technique. The result was in agreement with that obtained from the measurements of heat capacities.

The 4,5-dihydro-1,2,4-triazole Schiff base derivatives were synthesized with 4-amino-4,5-dihydro-3-(phenoxy- methyl)-1H-1,2,4-triazole-5-thione and substituted benzaldehydes. The chemical structures of the compounds have been confirmed by 1H NMR, IR spectra and elemental analysis. Their biological activities were investigated, and the results showed that they exhibited good fungicidal activities.

Eight Schiff bases of 3-amino-1H-1,2,4-triazole have been synthesized by glacial acetic acid catalyzed condensation of 3-amino-1H-1,2,4-triazole with substituted benzaldehyde and structurally confirmed by IR, 1H NMR and elemental analysis. The preliminary bioassay showed that the title compounds exhibited good fungicidal activities.

Eight Schiff bases have been synthesized using 3-alkyl-4-amino-1,2,4-triazole-5-thione and substituted benzaldehyde as starting materials. The structures of the compounds have been confirmed by 1H NMR, IR and elemental analysis and their biological activities to five vegetable pathogens have been tested. The results showed that they exhibited good fungicidal activities.