Achieving structurally stable O3-type layered oxide cathodes through site-specific cation-anion co-substitution for sodium-ion batteries

O3-type layered oxides have garnered great attention as cathode materials for sodium-ion batteries because of their abundant reserves and high theoretical capacity.However,challenges persist in the form of uncontrollable phase transitions and intricate Na^(+)diffusion pathways during cycling,resulting in compromised structural stability and reduced capacity over cycles.This study introduces a special approach employing site-specific Ca/F co-substitution within the layered structure of O_(3)-NaNi_(0.5)Mn_(0.5)O_(2) to effectively address these issues.Herein,the strategically site-specific doping of Ca into Na sites and F into O sites not only expands the Na^(+)diffusion pathways but also orchestrates a mild phase transition by suppressing the Na^(+)/vacancy ordering and providing strong metal-oxygen bonding strength,respectively.The as-synthesized Na_(0.95)Ca_(0.05)Ni_(0.5)Mn_(0.5)O_(1.95)F_(0.05)(NNMO-CaF)exhibits a mild O3→O3+O'3→P3 phase transition with minimized interlayer distance variation,leading to enhanced structural integrity and stability over extended cycles.As a result,NNMO-CaF delivers a high specific capacity of 119.5 mA h g^(-1)at a current density of 120 mA g^(-1)with a capacity retention of 87.1%after 100 cycles.This study presents a promising strategy to mitigate the challenges posed by multiple phase transitions and augment Na^(+)diffusion kinetics,thus paving the way for high-performance layered cathode materials in sodium-ion batteries.

Effects of Site-Specific Nitrogen Management on Yield and Dry Matter Accumulation of Rice from Cold Areas of Northeastern China

The effects of yield increase and mechanism of site-specific nitrogen management （SSNM） in five rice varieties from cold areas of northeastern China were studied. Plot experiment for critical SPAD value and experiments of two fertilization methods, SSNM and farmer＇s fertilization practice （FFP） were conducted to study their effects on the quality and dry matter accumulation of rice population, as well as N uptake. Compared with FFP, SSNM significantly decreased the average N rate by 33.8%, significantly increased average ear-bearing tiller rate and LAI for grain-filling stage by 12.3% and 14.1-27.6%, correspondingly, improved dry matter weight and N uptake after heading period by 4.3-29.1% and 11.8-55.1% （P 〈 0.05）, and heightened recovery efficiency and agronomic efficiency by 38.5-133.4% （P 〈 0.05） and 39.8-194.3% （P 〈 0.05）, respectively, as well as increased the average yield by 9.8% in 2004 and 2005. The results indicated that the accumulation rate of dry matter and N increased the rice yield and N use efficiency, because of improving rice population quality and increasing LAI after heading period.

Spatial variability of soil properties in red soil and its implications for site-specific fertilizer management

Assessing spatial variability and mapping of soil properties constitute important prerequisites for soil and crop management in agricultural areas. To explore the relationship between soil spatial variability and land management, 256 samples were randomly collected at two depths (surface layer 0–20 cm and subsurface layer 20–40 cm) under different land use types and soil parent materials in Yujiang County, Jiangxi Province, a red soil region of China. The pH, soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), and base saturation (BS) of the soil samples were examined and mapped. The results indicated that soils in Yujiang were acidified, with an average pH of 4.87 (4.03–6.46) in the surface layer and 4.99 (4.03–6.24) in the subsurface layer. SOM and TN were significantly higher in the surface layer (27.6 and 1.50 g kg–1, respectively) than in the subsurface layer (12.1 and 0.70 g kg–1, respectively), while both CEC and BS were low (9.0 and 8.0 cmol kg–1, 29 and 38% for surface and subsurface layers, respectively). Paddy soil had higher pH (mean 4.99) than upland and forest soils, while soil derived from river alluvial deposits (RAD) had higher pH (mean 5.05) than the other three parent materials in both layers. Geostatistical analysis revealed that the best fit models were exponential for pH and TN, and spherical for BS in both layers, while spherical and Gaussian were the best fitted for SOM and CEC in the surface and subsurface layers. Spatial dependency varied from weak to strong for the different soil properties in both soil layers. The maps produced by selecting the best predictive variables showed that SOM, TN, and CEC had moderate levels in most parts of the study area. This study highlights the importance of site-specific agricultural management and suggests guidelines for appropriate land management decisions.

Construction of Marker-Free GFP Transgenic Tobacco by Cre/lox Site-Specific Recombination System

Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanked by recombination sites in a directed orientation. The Bar gene expression box was subsequently excised from the plant genome by a strategy of Cre gene retransformation. After removal of the Cre-NPT Ⅱ locus by genetic segregation through self-cross, plants that incorporated only the GFP transgene were obtained. Transgenic tobacco plants mediated by Agrobacterium tumefaciens were obtained, which resisted herbicide Basta and GFP expressed well, then the Cre gene was subsequently introduced into 5 plants of them, respectively, by retransformation. The leaf disks from Cre transgenic plants were used to test the resistance to Basta on the medium with 8 mg L-1 of PPT. The results showed that few discs were able to regenerate normally, and the excision at 76-100% efficiency depended on individual retransformation events. Evidence for a precise recombination event was confirmed by cloning the nucleotides sequence surrounding the lox sites of the Basta sensitive plants. The result indicated that the excision event in the recombination sites was precise and conservative, without loss or alteration of any submarginal nucleotides of the recombination sites. Bar gene excised plants were selfpollinated to allow segregation of the GFP gene from the Cre-NPT Ⅱ locus. The progenies from self-pollinated plants were scored for Kan senstivity, then the segregation of GFP gene from Cre-NPT Ⅱ locus in the Kan senstive plants were confirmed by PCR analysis subsequently. Hence, constructing marker-free transgenic tobacco plants by Cre/lox sitespecific recombination system was reliable, and the strategy presented here should be applicable to other plants for the construction of marker-free transgenic plants as well.

Development of a radiolabeled site-specific single-domain antibody positron emission tomography probe for monitoring PD-L1 expression in cancer

Despite advances in immunotherapy for the treatment of cancers,not all patients can benefit from programmed cell death ligand 1(PD-L1)immune checkpoint blockade therapy.Anti-PD-L1 therapeutic effects reportedly correlate with the PD-L1 expression level;hence,accurate detection of PD-L1 expression can guide immunotherapy to achieve better therapeutic effects.Therefore,based on the high affinity antibody Nb109,a new site-specifically radiolabeled tracer,^(68)Ga-NODA-cysteine,aspartic acid,and valine(CDV)-Nb109,was designed and synthesized to accurately monitor PD-L1 expression.The tracer ^(68)Ga-NODA-CDV-Nb109 was obtained using a site-specific conjugation strategy with a radiochemical yield of about 95%and radiochemical purity of 97%.It showed high affinity for PD-L1 with a dissociation constant of 12.34±1.65 nM.Both the cell uptake assay and positron emission tomography(PET)imaging revealed higher tracer uptake in PD-L1-positive A375-hPD-L1 and U87 tumor cells than in PD-L1-negative A375 tumor cells.Meanwhile,dynamic PET imaging of a NCI-H1299 xenograft indicated that doxorubicin could upregulate PD-L1 expression,allowing timely interventional immunotherapy.In conclusion,this tracer could sensitively and dynamically monitor changes in PD-L1 expression levels in different cancers and help screen patients who can benefit from anti-PD-L1 immunotherapy.

The Site-Specific Hydrolysis of l-β-Hydroxybaccatin Ⅱ by Aspergillus Niger

The site-specific microbiological hydrolysis of a natural 1β-hydroxybaccatin I, with the culture of Aspergillus niger. is described.

Application of site-specific biomass models to quantify spatial distribution of stocks and historical emissions from deforestation in a tropical forest ecosystem

Allometric equations developed for the Lama forest, located in southern Benin, West Africa, were applied to estimate carbon stocks of three vegetation types：undisturbed forest, degraded forest, and fallow. Carbon stock of the undisturbed forest was 2.7 times higher than that in the degraded forest and 3.4 times higher than that in fallow. The structure of the forest suggests that the individual species were generally concentrated in lower diameter classes. Carbon stock was positively correlated to basal area and negatively related to tree density, suggesting that trees in higher diameter classes contributed significantly to the total carbon stock. The study demonstrated that large trees constitute an important component to include in the sampling approach to achieve accurate carbon quantification in forestry. Historical emissions from deforestation that converted more than 30% of the Lama forest into cropland between the years 1946 and 1987 amounted to 260,563.17 tons of carbon per year（t CO2/year） for the biomass pool only. The study explained the application of biomass models and ground truth data to estimate reference carbon stock of forests.

Study on Site-specific Nutrient Management in Cotton Field

The study on the characteristics of spatial variability of soil nutrients and fertilizer recommendations in cotton field under certain conditions of agricultural management was conducted with GIS and systematic approach for soil nutrient constrains. The results showed that of the spatial variability of soil nutrient was greatly related to the management condition of previous crops. Grid sampling and variable rate application technology (VRAT) were the tools that would hopefully increase fertilizer efficiency. The fertilizers were applied where they were needed and at proper rate. Balance fertilization demonstration showed that fertilizer recommendations according to the available nutrient level in soil could decrease fertilizer cost with 657.4 yuan / ha and increase seed cotton yield by 19.8%. A net profit of the balanced fertilization was 5314.9 yuan / ha higher than that of local fertilization practice.

Development of rabbit monoclonal and polyclonal antibodies for detection of site-specific histone modifications and their application in analyzing overall modification levels

In addition to DNA sequence information, site-specific histone modifications are another important determinant of gene expression in a eukaryotic organism. We selected four modification sites in common histones that are known to significantly impact chromatin function and generated monoclonal or polyclonal antibodies that recognize each of those site-specific modifications. We used these antibodies to demonstrate that the site-specific histone modification levels remain relatively constant in different organs of the same organism. We also compared the levels of selected histone modifications among several representative organisms and found that site-specific modifications are highly variable among different organisms, providing new insight into the evolutionary divergence of specific histone modifications.

Effects of Long-term Site-specific Fertilization on Soil Physical and Chemical Properties and Nutrients in Dry Farmland

In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farmland, the soil p H, total salt content,crop root length, root weight, soil organic matter, available nitrogen, total nitrogen, total phosphorous and total potassium in different fertilization treatments were measured from 2010 to 2016. Multiple comparisons of the data were performed using Duncan's new multiple range test. The results indicated that in the 0-20 cm soil layer, soil p H value and total salt content changed in different patterns, and varied greatly from 2010 to 2016(P<0.05). The changes of both root length and root weight of millet over time fitted S-shaped curves. The root length and root weight in the four fertilization treatments(Treatment 2 to Treatment5) increased faster than those in the control(Treatment 1). The soil organic matter content in all the five treatments gradually increased from 2010 to 2016. The content of alkaline hydrolyzable nitrogen in soil rapidly increased in the first two to three years of the experiment, followed by a slow increase or decrease in 2013, and then raised rapidly again from 2014 to 2016.The soil total nitrogen content varied significantly from 2010 to 2016. The total phosphorus content in soil changed in a different pattern from that of total nitrogen content. The seven-year field trails revealed that soil p H, total salt content, root length, root weight and soil nutrient all changed with the increase of fertilizer level, and that long-term fertilization is of significance for maintaining soil fertility, improving soil quality and reducing soil salinization.

Chemotactic Activity of Site-Specific Multivalent Conjugates of Stromal Cell-Derived Factor 1<i>α</i>on Branched Nanoparticles

Stromal cell-derived factor 1α (SDF1α) is a potent chemokine for the recruitment of stem cells. A challenge is to maintain its activity and control its release. In this study, we engineered a recombinant cysteine-SDF1α (cysSDF1α) protein, and performed multivalent conjugation of cysSDF1 through the maleimide functional group to two forms of branched nanoparticles: multi-arm poly (ethylene glycol) (MA-PEG) and hyaluronic acid (HA). We characterized the chemotactic activity of the conjugates, and determined how the molecular weight (MW) of MA-PEG and HA affected the chemotactic activity. CysSDF1α had similar efficiency to wild-type SDF1α in cell recruitment. Multivalent conjugation of cysSDF1α to low MW MA-PEG (~18 nm) did not significantly affect the chemotactic activity, while the conjugation of cysSDF1α to high MW MA-PEG (~72 nm) lowered the efficiency, possibly due to the larger spacing between conjugated SDF1α molecules. HA has a linear backbone and a high density of multivalent binding sites;however, the chemotactic activity of HA-linked cys-SDF1α was much lower, which further decreased with the increase of HA MW from 200 kDa (~0.78 μm) to 700 kDa (~2.7 μm). Digestion of HA into smaller fragments using hyaluronidase partially recovered the chemotactic activity of cysSDF1α, suggesting that high MW HA might exert steric hindrance for SDF1α binding to its receptors on cell surface and that HA could be used as a depot for SDF1α storage and release. These results demonstrate that multivalent conjugates of SDF1α to nanoparticles may be used to engineer SDF1α delivery for cell recruitment and tissue regeneration.

Site-specific recombination in Escherichia coli mediated by actinomyces phage R4 integrase

The purpose of this study was to demonstrate that actinomyces phage R4 integrase Sre protein efficiently mediate site-specific recombination in Escherichia coll. An intramolecular recombination assay system in E. coli was constructed. The plasmid pBZP contains attB and attP sites in direct orientation flanking a lacZ gene. When pBZP was introduced into E. coli cells, in which the plasmid pSREA containing sre gene was resident, Sre protein catalyzed integration of attP into attB site, resulting in excision of the lacZ gene. This integration changed bacteria colonies from blue to white on agar plates containing X-Gal, which showed that the lacZ was removed. The integrant DNAs were identified by enzyme digestion, PCR and DNA sequencing. The minimal sizes of attB and attP were 50 bp and 47 bp for 100% recombination efficiency. The phage recombinase Sre efficiently integrated attP into attB site to create attR and attL in E. coli host environment without Streptomyces specific cofactors. This intrmolecular assay system is a simple and efficient system for Sre-mediated recombination in E. coll.

Probing the active sites of site-specific nitrogen doping in metal-free graphdiyne for electrochemical oxygen reduction reactions

The development of highly active and low-cost catalysts for electrochemical reactions is one of the most attractive topics in the renewable energy technology.Herein,the site-specific nitrogen doping of graphdiyne(GDY)including grap-N,sp-N(Ⅰ)and sp-N(Ⅱ)GDY is systematically investigated as metal-free oxygen reduction electrocatalysts via density functional theory(DFT).Our results indicate that the doped nitrogen atom can significantly improve the oxygen(O2)adsorption activity of GDY through activating its neighboring carbon atoms.The free-energy landscape is employed to describe the electrochemical oxygen reduction reaction(ORR)in both O2 dissociation and association mechanisms.It is revealed that the association mechanism can provide higher ORR onset potential than dissociation mechanism on most of the substrates.Especially,sp-N(Ⅱ)GDY exhibits the highest ORR electrocatalytic activity through increasing the theoretical onset potential to 0.76 V.This work provides an atomic-level insight for the electrochemical ORR mechanism on metal-free N-doped GDY.

Molecular engineering of antibodies for site-specific conjugation to lipid polydopamine hybrid nanoparticles

Conjugation of antibodies to nanoparticles allows specific cancer targeting,but conventional conjugation methods generate heterogeneous conjugations that cannot guarantee the optimal orientation and functionality of the conjugated antibody.Here,a molecular engineering technique was used for sitespecific conjugation of antibodies to nanoparticles.We designed an anti-claudin 3(CLDN3)antibody containing a single cysteine residue,h4 G3 cys,then linked it to the maleimide group of lipid polydopamine hybrid nanoparticles(LPNs).Because of their negatively charged lipid coating,LPNs showed high colloidal stability and provided a functional surface for site-specific conjugation of h4 G3 cys.The activity of h4 G3 cys was tested by measuring the binding of h4 G3 cys-conjugated LPNs(C-LPNs)to CLDN3-positive tumor cells and assessing its subsequent photothermal effects.C-LPNsspecifically recognized CLDN3-overexpressing T47 D breast cancer cells but not CLDN3-negative Hs578 T breast cancer cells.High binding of C-LPNs to CLDN3-overexpressing T47 D cells resulted in significantly higher temperature generation upon NIR irradiation and potent anticancer photothermal efficacy.Consistent with this,intravenous injection of C-LPNsin a T47 D xenograft mouse model followed by NIR irradiation caused remarkable tumor ablation compared with other treatments through high temperature increases.Our results establish an accurate antibody-linking method and demonstrate the possibility of developing therapeutics using antibody-guided nanoparticles.

One-step synthesis of site-specific antibody-drug conjugates by reprograming IgG glycoengineering with LacNAc-based substrates

Glycosite-specific antibody-drug conjugatess(gsADCs), harnessing Asn297 N-glycan of IgG Fc as the conjugation site for drug payloads, usually require multi-step glycoengineering with two or more enzymes, which limits the substrate diversification and complicates the preparation process.Herein, we report a series of novel disaccharide-based substrates, which reprogram the IgG glycoengineering to one-step synthesis of gsADCs, catalyzed by an endo-N-acetylglucosaminidase(ENGase) of Endo-S2. IgG glycoengineering via ENGases usually has two steps: deglycosylation by wild-type(WT) ENGases and transglycosylation by mutated ENGases. But in the current method, we have found that disaccharide LacNAc oxazoline can be efficiently assembled onto IgG by WT Endo-S2 without hydrolysis of the product, which enables the one-step glycoengineering directly from native antibodies.Further studies on substrate specificity revealed that this approach has excellent tolerance on various modification of 6-Gal motif of LacNAc. Within 1 h, one-step synthesis of gsADC was achieved using the LacNAc-toxin substrates including structures free of bioorthogonal groups. These gsADCs demonstrated good homogeneity, buffer stability, in vitro and in vivo anti-tumor activity. This work presents a novel strategy using LacNAc-based substrates to reprogram the multi-step IgG glycoengineering to a one-step manner for highly efficient synthesis of gsADCs.

Site-specific PEGylation of lidamycin and its antitumor activity

In this study,N-terminal site-specific mono-PEGylation of the recombinant lidamycin apoprotein(r LDP) of lidamycin(LDM) was prepared using a polyethyleneglycol(PEG) derivative(Mw20 k Da) through a reactive terminal aldehyde group under weak acidic conditions(p H 5.5).The biochemical properties of m PEG-r LDP-AE,an enediyne-integrated conjugate,were analyzed by SDSPAGE,RP-HPLC,SEC-HPLC and MALDI-TOF.Meanwhile,in vitro and in vivo antitumor activity of m PEG-r LDP-AE was evaluated by MTT assays and in xenograft model.The results indicated that m PEGr LDP-AE showed significant antitumor activity both in vitro and in vivo.After PEGylation,m PEG-r LDP still retained the binding capability to the enediyne AE and presented the physicochemical characteristics similar to that of native LDP.It is of interest that the PEGylation did not diminish the antitumor efficacy of LDM,implying the possibility that this derivative may function as a payload to deliver novel tumortargeted drugs.

Establishment and application of both FLP and Cre site-specific recombination systems at the same position in the genome

Both FRT-FRT and LoxP-LoxP sites that are the target sepuences of site-specific recombinases have been constructed in a vector, called C4LFY, using the recombinant DNA technigue. C4LFY also contains P elements, 2 exons and 1 intron of Drosophila yellow gene, yellow promoter and enhancers, and flanking DNA. Since C4LFY made use of two pairs of FRT and LoxP sites, this vector included two site-specific recombination systems. C4LFY was then integrated into Drosophila genome by P-element-mediated germ line transformation. in the presence of the FLP or Cre recombinase, either FLP/FRT or Cre/LoxP recombination reaction was successfully created at the same position in the genome. Using this system, the molecular basis of yellow gene expression and regulation during development have been investigated. Results indicate that the tissue-specific expression of yellow gene is directly regulated by transcriptional enhancers. in addition, the 5’ and 3’ genomic sequences flanking the yellow gene have been

Site-specific Deposition of Colloidal Pd Nanoparticles on Self-assembled Microtubules from Biolipid

Lipid microtubules with wound ribbon features were fabricated by self-assembling method, and the deposition patterns of colloidal Pd particles on tubular template were investigated. The result indicates that colloidal Pd nanoparticles are preferentially decorated on the helical markings in the interior and on the exterior of preformed tubule and to the edge of loosely helical ribbons to obtain helical deposition features. The multi-bilayer microstruc-ture of tubules can be marked by fine Pd nanoparticles deposited at the edge of helical ribbon. There are the site-specific interactions between lipid tubular template and colloidal Pd particles at the helical edge. A new route was illustrated that colloidal Pd particles firstly attach at the edge of thin flat membranes, and then thin membranes roll up and reassemble into tubule together with particles to form helical deposition patterns. The site-specific depo-sition of Pd is unbeneficial to obtain the homogeneous metal film on tubules, but it can be utilized to reveal the dif-ferent chemical nature of lipid molecular assembly.

An integrated approach to site-specific management zone delineation

Dividing fields into a few relatively homogeneous management zones(MZs) is a practical and costeffective approach to precision agriculture. There are three basic approaches to MZ delineation using soil and/or landscape properties, yield information, and both sources of information. The objective of this study is to propose an integrated approach to delineating site-specific MZ using relative elevation, organic matter, slope, electrical conductivity, yield spatial trend map, and yield temporal stability map(ROSE-YSTTS) and evaluate it against two other approaches using only soil and landscape information(ROSE) or clustering multiple year yield maps(CMYYM). The study was carried out on two no-till corn-soybean rotation fields in eastern Illinois, USA. Two years of nitrogen(N) rate experiments were conducted in Field B to evaluate the delineated MZs for site-specific N management. It was found that in general the ROSE approach was least effective in accounting for crop yield variability(8.0%–9.8%), while the CMYYM approach was least effective in accounting for soil and landscape(8.9%–38.1%), and soil nutrient and pH variability(9.4%–14.5%). The integrated ROSE-YSTTS approach was reasonably effective in accounting for the three sources of variability(38.6%–48.9%, 16.1%–17.3% and 13.2%–18.7% for soil and landscape, nutrient and pH, and yield variability, respectively), being either the best or second best approach. It was also found that the ROSE-YSTTS approach was effective in defining zones with high,medium and low economically optimum N rates. It is concluded that the integrated ROSE-YSTTS approach combining soil, landscape and yield spatial-temporal variability information can overcome the weaknesses of approaches using only soil, landscape or yield information,and is more robust for MZ delineation. It also has the potential for site-specific N management for improved economic returns. More studies are needed to further evaluate their appropriateness for precision N and crop management.

STUDY ON MULTI-POINT SITE-SPECIFIC MUTAGENESIS——DOUBLE-POINT SITE-SPECIFIC MUTAGENESIS FOR MODIFYING α-HUMAN ATRIAL NATRIURETIC PEPTIDE GENE

Although oligonucleotide-directed mutagenesis has been widely applied in the field of molecular biology, this method has some disadvantages: It is time-consuming and overelaborate, besides only a single base mutation of the gene can be obtained by a single operation.