Contribution of Vehicle Emission and NO2 Surface Conversion to Nitrous Acid (HONO) in Urban Environments: Implications from Tests in a Tunnel.

Nitrous acid (HONO) is an important photochemical precursor to hydroxyl radicals particularly in an urban atmosphere, yet its primary emission and secondary production are often poorly constrained. Here, we measured HONO and nitrogen oxides (NOx) at both the inlet and the outlet in a busy urban tunnel (>30 000 vehicles per day) in south China. Multiple linear regression revealed that 73.9% of the inlet-outlet incremental HONO concentration was explained by NO2 surface conversion, while the rest was directly emitted from vehicles with an average HONO/NOx ratio of 1.31 ± 0.87%, which was higher than that from previous tunnel studies. The uptake coefficient of NO2, γ(NO2), on the tunnel surfaces was calculated to be (7.01 ± 0.02) × 10-5, much higher than that widely used in models. As tunnel surfaces are typical of urban surfaces in the wall and road materials, the dominance of HONO from surface reactions in the poorly lit urban tunnel demonstrated the importance of NO2 conversion on urban surfaces, instead of NO2 conversion on the aerosol surface, for both daytime and night-time HONO even in polluted ambient air. The higher γ(NO2) on urban surfaces and the elevated HONO/NOx ratio from this study can help explain the missing HONO sources in urban areas.

A Discrete Tetrahedral Indium Cage as an Efficient Heterogeneous Catalyst for the Fixation of CO2 and the Strecker Reaction of Ketones.

A discrete tetrahedral indium cage, {[In12(µ3-OH)4(HCO2)24(tcma)4]} (In12-GL), was synthesized solvothermally by the reaction of indium nitrate with the tripodal tricarboxylic acid ligand N,N,N-tris{(2'-carboxy[1,1'-biphenyl]-4-yl)methyl}methylammonium chloride ([H3tcma]+Cl). This cage consists of four trimeric units [In3(µ3-OH)(µ2-CO2)3(µ2-HCO2)3] and four [tcma]2- ligands, which all perform as 3-connection nodes to bridge each other, resulting in a tetrahedral cage structure. The trimeric unit [In3(µ3-OH)(µ2-CO2)3(µ2-HCO2)3] is observed for the first time in the family of In-based metal-organic structures and can be considered as an evolution of a 6-connected [In3(µ3-O)(µ2-CO2)6] unit. Each In3+ is terminally coordinated by a µ1-HCO2 group. This cage contains potential Lewis acidic/basic active sites endowed by In3+ ions as Lewis acidic sites and the uncoordinated oxygen atoms of µ1-HCO2 moieties as Lewis basic sites and was explored as an effective heterogeneous catalyst in the cycloaddition of CO2 with epoxides and the Strecker reaction for amino nitriles. These catalytic reactions were deduced to happen on the surface of the In12-GL cage.

Vertical profiles of biogenic volatile organic compounds as observed online at a tower in Beijing.

Vertical profiles of isoprene and monoterpenes were measured by a proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) at heights of 3, 15, 32, 64, and 102 m above the ground on the Institute of Atmospheric Physics (IAP) tower in central Beijing during the winter of 2016 and the summer of 2017. Isoprene mixing ratios were larger in summer due to much stronger local emissions whereas monoterpenes were lower in summer due largely to their consumption by much higher levels of ozone. Isoprene mixing ratios were the highest at the 32 m in summer (1.64 ± 0.66 ppbV) and at 15 m in winter (1.41 ± 0.64 ppbV) with decreasing concentrations to the ground and to the 102 m, indicating emission from the tree canopy of the surrounding parks. Monoterpene mixing ratios were the highest at the 3 m height in both the winter (0.71 ± 0.42 ppbV) and summer (0.16 ± 0.10 ppbV) with a gradual decreasing trend to 102 m, indicting an emission from near the ground level. The lowest isoprene and monoterpene mixing ratios all occurred at 102 m, which were 0.71 ± 0.42 ppbV (winter) and 1.35 ± 0.51 ppbV (summer) for isoprene, and 0.42 ± 0.22 ppbV (winter) and 0.07 ± 0.06 ppbV (summer) for monoterpenes. Isoprene in the summer and monoterpenes in the winter, as observed at the five heights, showed significant mutual correlations. In the winter monoterpenes were positively correlated with combustion tracers CO and acetonitrile at 3 m, suggesting possible anthropogenic sources.

Heterogeneous chemistry of ozone with floor cleaning agent: Implications of secondary VOCs in the indoor environment.

Human daily activities such as cooking, and cleaning can affect the indoor air quality by releasing primary emitted volatile organic compounds (VOCs), as well as by the secondary product compounds formed through reactions with ozone (O3) and hydroxyl radicals (OH). However, our knowledge about the formation processes of the secondary VOCs is still incomplete. We performed real-time measurements of primary VOCs released by commercial floor-cleaning detergent and the secondary product compounds formed by heterogeneous reaction of O3 with the constituents of the cleaning agent by use of high-resolution mass spectrometry. We measured the uptake coefficients of O3 on the cleaning detergent at different relative humidities in dark and under different light intensities (320 nm < λ < 400 nm) relevant for the indoor environment. On the basis of the detected compounds we developed tentative reaction mechanisms describing the formation of the secondary VOCs. Intriguingly, under light irradiation the formation of valeraldehyde was observed based on the photosensitized chemistry of acetophenone which is a constituent of the cleaning agent. Finally, we modeled the observed mixing ratios of three aldehydes, glyoxal, methylglyoxal, and 4-oxopentanal with respect to real-life indoor environment. The results suggest that secondary VOCs initiated by ozone chemistry can additionally impact the indoor air pollution.

An Overview of the Isoprenoid Emissions From Tropical Plant Species.

Terrestrial vegetation is the largest contributor of isoprenoids (a group of biogenic volatile organic compounds (BVOCs)) to the atmosphere. BVOC emission data comes mostly from temperate regions, and less is known about BVOC emissions from tropical vegetation, even though it is estimated to be responsible for >70% of BVOC emissions. This review summarizes the available data and our current understanding of isoprenoid emissions from tropical plant species and the spatial and temporal variation in emissions, which are strongly species-specific and regionally variable. Emission models lacking foliar level data for tropical species need to revise their parameters to account for seasonal and diurnal variation due to differences in dependencies on temperature and light of emissions from plants in other ecosystems. More experimental information and determining how emission capacity varies during foliar development are warranted to account for seasonal variations more explicitly.

Emissions and light absorption of PM2.5-bound nitrated aromatic compounds from on-road vehicle fleets.

Vehicle emissions are an important source of nitrated aromatic compounds (NACs) in particulate size smaller 2.5 µm (PM2.5), which adversely affect human health and biodiversity, especially in urban areas. In this study, filter-based PM2.5 samples were collected during October 14-19, 2019, in a busy urban tunnel (approximately 35,000 vehicles per day) in south China to identify PM2.5-bound NACs. Among them, 2,8-dinitrodibenzothiophene, 3-nitrodibenzofuran and 2-nitrodibenzothiophene were the most abundant nitrated polycyclic aromatic hydrocarbons (NPAHs), while 2-methyl-4-nitrophenol, 2,4-dinitrophenol, 3-methyl-4-nitrophenol and 4-nitrophenol were the most abundant nitrophenols (NPs). The observed mean fleet emission factors (EFs) of NPAHs and NPs were 2.2 ± 2.1 and 7.7 ± 4.1 µg km-1, and were 2.9 ± 2.7 and 10.2 ± 5.4 µg km-1 if excluding electric and liquefied petroleum gas vehicles, respectively. Regression analysis revealed that diesel vehicles (DVs) had NPAH-EFs (55.3 ± 5.3 µg km-1) approximately 180 times higher than gasoline vehicles (GVs) (0.3 ± 0.2 µg km-1), and NP-EFs (120.6 ± 25.8 µg km-1) approximately 30 times higher than GVs (4.1 ± 0.2 µg km-1), and thus 89% NPAH emissions and 56% NP emissions from the onroad fleets were contributed by DVs although DVs only accounted for 3.3% in the fleets. Methanol solution-based light absorption measurements demonstrated that the mean incremental light absorption for methanol-soluble brown carbon at 365 nm was 6.8 ± 2.2 Mm-1, of which the 44 detected NACs only contributed about 1%. The mean EF of the 7 toxic NACs was approximately 3% that of the 16 priority PAHs; However, their benzo(a)pyrene toxic equivalence quotients (TEQBaP) could reach over 25% that of the PAHs. Moreover, 6-nitrochrysene mainly from DVs contributed 93% of the total TEQBaP of the NACs. This study demonstrated that enhancing DV emission control in urban areas could benefit the reduction of exposure to air toxins such as 6-nitrochrysene.

Electrostatic assembly construction of polysaccharide functionalized hybrid membrane for enhanced antimony removal.

There is a growing demand for heavy metal removal by membrane technology in real applications. However, few studies were reported concerning antimony (Sb) removal by membrane technology. Herein, a novel thin film nanocomposite (TFN) membrane comprising an alginate (SA) selective layer and a polyether sulfone (PSF) support membrane incorporating chitosan functionalized iron nanocomposite has been firstly developed for Sb removal via electrostatic self-assembly. The support matrix membrane contained iron nanocomposite (denoted as CIM) retained high water flux and porosity, and it reached a maximum removal capacity of 16.5 and 13.6 mg/g for Sb(III) and Sb(V) with nanofiller loading rate of 20% during static experiments, respectively. The coated SA top layer endowed the hybrid membrane (denoted as SA-CIM) to have a lower membrane flux, and have stronger retention abilities for Sb species than that by CIM during dynamic filtration experiments. The SA-CIM membranes also possess tolerable reversibility towards Sb removal. Benefiting from the negatively-charged dense selective layer and high adsorption capacity of the iron nanocomposites, the SA-CIM membranes demonstrated an enhanced removal capacity for Sb species via steric hindrance effect, electrostatic repulsion and adsorption. Our study offers a simple method to remove Sb by a novel polysaccharide functionalized hybrid membrane.

Bioinspired synthesis of fiber-shaped silk fibroin-ferric oxide nanohybrid for superior elimination of antimonite.

Bioinspired fibrous materials have emerged as a unique class of matrix for fabrication of fiber-shaped nanomaterial assemblies. Here, we report a novel functional fiber-shaped nanohybrid for efficient removal of antimonite via in situ synthesis of ferric oxides anchored to silk nanofibril. The silk nanofibril matrix played important roles in the growth of ferric oxides via metal-ligand interactions. The achieved nanocomposites had high surface areas and activity with more functional groups, contributing to superior antimonite elimination. The nanocomposite achieved a maximum removal capacity of 159.9 mg/g toward antimonite. And the common interfering ions of SO42-, NO3-, CO32-, PO43- and SiO32- exhibited negligible influence on antimonite removal. The mechanism study point that two factors are closely involved: surface complexation and hydrogen bonding. Benefiting from the low cost and environmental-friendly nature of silk fibroin as well as excellent removal capacity and high selectivity, it suggests that the nanohybrids might be promising for antimonite extraction from contaminated water.

Secondary organic aerosols produced from photochemical oxidation of secondarily evaporated biomass burning organic gases: Chemical composition, toxicity, optical properties, and climate effect.

Biomass burning (BB) is an important source of primary organic aerosols (POA). These POA contain a significant fraction of semivolatile organic compounds, and can release them into the gas phase during the dilution process in transport. Such evaporated compounds were termed "secondarily evaporated BB organic gases (SBB-OGs)" to distinguish them from the more studied primary emissions. SBB-OGs contribute to the formation of secondary organic aerosols (SOA) through reactions with atmospheric oxidants, and thus may influence human health and the Earth's radiation budget. In this study, tar materials collected from wood pyrolysis were taken as proxies for POA from smoldering-phase BB and were used to release SBB-OGs constantly in the lab. OH-initiated oxidation of the SBB-OGs in the absence of NOx was investigated using an oxidation flow reactor, and the chemical, optical, and toxicological properties of SOA were comprehensively characterized. Carbonyl compounds were the most abundant species in identified SOA species. Human lung epithelial cells exposed to an environmentally relevant dose of the most aged SOA did not exhibit detectable cell mortality. The oxidative potential of SOA was characterized with the dithiothreitol (DTT) assay, and its DTT consumption rate was 15.5 ± 0.5 pmol min-1 µg-1. The SOA present comparable light scattering to BB-POA, but have lower light absorption with imaginary refractive index less than 0.01 within the wavelength range of 360-600 nm. Calculations based on Mie theory show that pure airborne SOA with atmospherically relevant sizes of 50-400 nm have a cooling effect; when acting as the coating materials, these SOA can counteract the warming effect brought by airborne black carbon aerosol.

Emissions and light absorption of carbonaceous aerosols from on-road vehicles in an urban tunnel in south China.

With changing numbers, compositions, emission standards and fuel quality of on-road vehicles, it is imperative to accordingly characterize and update vehicular emissions of carbonaceous aerosols for better understanding their health and climatic effects. In this study, a 7-day field campaign was conducted in 2019 in a busy urban tunnel (>30,000 vehicles day-1) in south China with filter-based aerosol samples collected every 2 h at both the inlet and the outlet for measuring carbonaceous aerosols and their light absorbing properties. Observed fleet average emission factor (EF) of total carbon (TC) was 13.4 ± 8.3 mg veh-1 km-1, and 17.4 ± 11.3 mg veh-1 km-1 if electric and LPG-driven vehicles were excluded; and fleet average EF of organic carbon (OC) and elemental carbon (EC) was 8.5 ± 6.6 and 4.9 ± 2.6 mg veh-1 km-1 (11.0 ± 8.8 and 6.3 ± 3.6 mg veh-1 km-1 if excluding electric and LPG vehicles), respectively. Regression analysis revealed an average TC-EF of 319.8 mg veh-1 km-1 for diesel vehicles and 2.1 mg veh-1 km-1 for gasoline vehicles, and although diesel vehicles only shared ~4% in the fleet compositions, they still dominate on-road vehicular carbonaceous aerosol emissions due to their over 150 times higher average TC-EF than gasoline vehicles. Filter-based light absorption measurement demonstrated that on average brown carbon (BrC) could account for 19.1% of the total carbonaceous light absorption at 405 nm, and the average mass absorption efficiency of EC at 635 nm and that of OC at 405 nm were 5.2 m2 g-1 C and 1.0 m2 g-1 C, respectively.

[Single nucleotide polymorphisms in 22 HLA-Cw alleles in Chinese Han population].

To analyze the molecular genetic polymorphism of full-length HLA-Cw gene, a total of 28 samples with known genotypes from Chinese Han population were amplified by long-range PCR using high-fidelity Pfu polymerase. A fragment 4.5 kb in length of HLA-Cw gene was subjected to cloning and haplotype sequencing. The single nucleotide polymorphisms (SNPs) in all segments of the whole region of HLA-Cw gene were analyzed. As a result, we detected 22 different HLA-Cw alleles in 28 samples, all of which were submitted to GenBank and the IMGT/HLA Database. Among the 22 HLA-Cw alleles, the intronic sequences of Cw*030301, Cw*0706 and Cw*140201 were firstly elucidated. The novel intronic sequence and the SNPs information may help to design allele-specific primers for accurate sequence-based typing (SBT) and to avoid allele dropout events in SBT test. We aligned all the diploid sequences using ClustalX program and imported them into Dnasp4.0 to calculate polymorphism in all coding- and non-coding regions. We found 244 SNPs and 10 insertion/deletions (Indels). According to the analysis of polymorphism level, phylogenetic trees and frequency spectrum, we proposed that the evolution of intron 4 and exon 5 was under balancing selection. Selection on these segments indicated that they may be functionally important in evolution of HLA-Cw gene. The full-length sequences obtained and related SNPs information can be used as resources of markers for high-resolution typing, complex diseases association studies and human evolution.

[An analysis of the reason for HLA-C allele dropout in five samples by sequence-based typing].

OBJECTIVE: To analyze the possible reason for HLA-C allele dropout in routine sequence-based typing (SBT) and improve the accuracy of HLA-C SBT test. METHODS: A total of 620 randomly selected samples from healthy voluntary blood donors in Shenzhen were typed at HLA-C locus by sequence-based typing using the AlleleSEQR HLA-C plus sequence-based typing kit. Samples with no full match result were subjected to cloning and haplotype sequencing of the full-length HLA-C gene. If no novel mutations were found, samples were then retyped, using our self-designed PCR primer pair and PCR conditions replacing the AlleleSEQR HLA-C PCR reagents in the PCR set-up procedure so as to analyze the potential reasons for causing abnormal SBT result. RESULTS: In the 620 samples typed at HLA-C locus using the AlleleSEQR HLA-C SBT commercial kit, 5 samples with no full match result were identified. The closest genotype showed one nucleotide mismatch with many different allele groups at different nucleotide position. Based on the PCR-SBT nucleotide sequence, heterozygous nucleotides were determined only in exon 4, whereas the nucleotides in exon 2 and 3 were all homozygotes. The results showed that HLA-Cw*0706 allele dropout existed in all the 5 samples with abnormal SBT results initially identified by AlleleSEQR HLA-C SBT kit, no novel mutation was found. CONCLUSION: The results indicate that the PCR primer pair incompatible with DNA template may result in allele dropout in HLA-C SBT test. Based on the characterization of HLA-C full-length, it is essential to develop HLA-C SBT kit suitable for Chinese population in the future.

[Establishment of an assay for cloning and sequencing the full-length HLA-Cw gene].

OBJECTIVE: To establish a reliable assay for cloning and sequencing the full-length HLA-Cw gene. METHODS: In this study, a fragment of 4.5 kb full-length HLA-Cw gene was amplified using the self-designed PCR primer pair by long template PCR, purified PCR products was cloned into the pGEM-Teasy plasmid vector and the plasmid DNA isolated from positive clones was subjected to haplotype sequencing by both directions. A total of 12 samples having been previously-genotyped by PCR sequence-based-typing (PCR-SBT) were amplified by using the TaKaRa LA Taq and Stratagene Pfu polymerase, respectively. PCR products of full length HLA-Cw gene were subjected to cloning and sequencing and the obtained haplotype sequence were compared with the PCR-SBT results. RESULTS: The specific target fragment of HLA-Cw gene could be amplified and the full-length HLA-Cw allele sequence covering from nucleotide position -962 in 5'untranslated region (5'-UTR) to nucleotide position 3576 in downstream area of 3'-UTR region could be obtained using our method. The results of cloning and sequencing analysis indicated that the Stratagene Pfu polymerase had better fidelity than the TaKaRa LA Taq polymerase in this experiment. By comparing the sequences of Cw*07020101 with Cw*010201, 11 SNPs as well as 2 insertions/deletions in nt-962--284 of 5'-UTR, and 11 SNPs as well as 1 insertion/deletion in nt3067-3576 downstream of 3'-UTR were identified. CONCLUSION: Our results indicate that the technique for cloning and sequencing full-length HLA-Cw gene has been established, it has a broad application in full-length HLA-Cw gene polymorphism study and the regulation and expression of HLA-Cw gene.

[µ-N,N'-Bis(diphenyl-phosphinometh-yl)benzene-1,4-diamine-κP:P']bis-[(2,2'-bipyridine-κN,N')silver(I)] bis-(per-chlorate) acetone disolvate.

The title complex, [Ag(2)(C(10)H(8)N(2))(2)(C(32)H(30)N(2)P(2))](ClO(4))(2)·2CH(3)COCH(3), is a centrosymmetric dimer with pairs of Ag(I) atoms bridged by N,N'-bis-(diphenyl-phosphinometh-yl)ben-zene-1,4-diamine ligands. In addition, each Ag(I) atom is coordin-ated by one chelating 2,2'-bipyridine ligand, giving a distorted trigonal coordination environment.

Development of a magnetic core-shell Fe3O4@TA@UiO-66 microsphere for removal of arsenic(III) and antimony(III) from aqueous solution.

Removal of trivalent species of As and Sb from wastewater is crucial due to their more toxic and mobile properties. In this study, a novel magnetic core-shell microsphere Fe3O4@TA@UiO-66 was developed via in-situ crystal growth of UiO-66 around the magnetic Fe3O4 modified by Tannic Acid (TA). Characterization of the microsphere by transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD) confirmed that UiO-66 was adhered on the surface of Fe3O4 functionalized by TA. Adsorption experiments showed that the magnetic Fe3O4@TA@UiO-66 had high adsorption capacity for As(III) and Sb(III) and could be rapidly separated from aqueous media within two minutes after treatment. The adsorption kinetics and adsorption isotherms were described well by the pesudo-second order model and Langmuir model, respectively. In addition, the composite exhibited excellent removal performance for As(III) and Sb(III) in a broad solution chemistry environment, including pH and co-existing anions. Based on X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) measurement, we proposed that the removal mechanism was mainly controlled through a synergistic interaction of surface complexation and hydrogen bonding. This study indicates the potential of the magnetic microsphere to be used as an effective material for the removal of As(III) and Sb(III) from water.

[Study on the gene polymorphism of Auberger antigens in Chinese population].

OBJECTIVE: To study the gene polymorphism of the Auberger antigens in Lutheran blood group system in Chinese population and establish a stable, accurate molecular method detecting Auberger antigens. METHODS: Peripheral blood samples from 162 randomly collected and unrelated volunteer blood donors were directly sequenced for the exon 12 at the gene locus of Auberger antigens. PCR products with novel nucleotide were further investigated by restriction fragment length polymorphism (RFLP) analysis. RESULTS: Auberger genotypes in the 162 Chinese individuals were obtained: Au(a+ b- )(nt1615A) was found in 119 individuals, Au(a+ b+ ) (nt1615A/G) in 40 individuals and Au(a- b+ ) (nt1615G) in 3 individuals. The allele frequencies of the Au(a) and Au(b) were 0.8580 and 0.1420, respectively. An individual with homozygous Au(a) genotype had a nucleotide mutation (1595 G to T). The mutation was confirmed by digesting the DNA with Hha I. CONCLUSION: The distribution of gene polymorphism of Auberger antigens in a Chinese population was investigated and obtained. And a molecular method determining the Auberger antigen was established. A novel Lutheran allele was deposited in GenBank (accession number EU260043).

Molecular polymorphism of O alleles in the Chinese Han population.

The ABO blood group system is the most important in transfusion medicine. O blood group is common in Chinese Han people, but the distribution of various O alleles is unknown. Sequences of exon6 and exon7 of the O allele at the ABO gene locus were studied in 100 individuals of the O phenotype randomly selected from the Chinese Han population. Some samples, when required, were cloned and sequenced spanning exon6 and exon7. Eight O alleles were found in the Chinese population. Most have the 2 common O01 or O02 alleles. The allele frequency of ABO*O01 was 0.47, and that of ABO*O02 was 0.495. One individual was found to have O05 allele. Five alleles were found to differ from all alleles reported to date. Four of these alleles differed from either the O01 allele (1 out of 4) or O02 allele (3 out of 4) by 1 point mutation at A468G, G489A, T526C, or T1104G. The fifth allele differed from the O01 allele since it does not have nt261G deletion but has C467T mutation. This novel allele occurred in 2 individuals. O genetic analysis suggests that the O01 allele prevails, with O1v accounting for about 97% of these in the Chinese Han population. The O03 allele that has been shown to occur with a frequency of <5% in other populations was not detected. But the novel O allele without 261G deletion has been found in Chinese for the first time. Surely more O alleles will be found in the Chinese population.

[Genetic polymorphisms of Y-STR haplotypes in unrelated male blood donors from the surname of Li, Wang and Zhang population in Shenzhen].

To study the genetic polymorphisms of Y-chromosome-specific STR loci in Chinese of different surnames, 9 Y-STR loci were amplified by single fluorescent multiplex PCR and the PCR products were detected by using ABI PrismTM 3100 DNA Sequencer. Samples were randomly-selected from male blood donors in ShenZhen. These individuals, who were otherwise unrelated, had the most common surnames among Chinese as their surnames, namely Li, Wang or Zhang. There were 139 subjects with surname Li, 118 with surname Wang and 119 with the surname Zhang. In the Li population, a total of 126 haplotypes was found and 118 of them were unique, with a haplotype diversity 0.9974. In the Wang population, a total of 105 haplotypes was found and 94 of them were unique, with a haplotype diversity of 0.9953. In the Zhang population, a total of 101 haplotypes was found and 88 of them were unique, with a haplotype diversity of 0.9964. Our results indicated that the genetic polymorphisms of Y-STR haplotypes at these 9 loci in unrelated male individuals with Chinese surnames of Li, Wang or Zhang are highly polymorphic and showed no significant differences with our previous data of haplotype polymorphisms in unrelated male individuals from the Chinese ethnic Han population.

The role of surface charge density in cationic liposome-promoted dendritic cell maturation and vaccine-induced immune responses.

Cationic liposomes have emerged as a novel adjuvant and antigen delivery system to enhance vaccine efficacy. However, the role of surface charge density in cationic liposome-regulated immune responses has not yet been elucidated. In the present study, we prepared a series of DOTAP/DOPC cationic liposomes with different surface densities by incorporating varying amounts of DOPC (a neutral lipid) into DOTAP (a cationic lipid). The results showed that DOTAP/DOPC cationic liposome-regulated immune responses relied on the surface charge density, and might occur through ROS signaling. The liposomes with a relatively high charge density, such as DOTAP/DOPC 5:0 and 4:1 liposomes, potently enhanced dendritic cell maturation, ROS generaion, antigen uptake, as well as the production of OVA-specific IgG2a and IFN-γ. In contrast, low-charge liposomes, such as DOTAP/DOPC 1:4 liposome, failed to promote immune responses even at high concentrations, confirming that the immunoregulatory effect of cationic liposomes is mostly attributable to their surface charge density. Moreover, the DOTAP/DOPC 1:4 liposome suppressed anti-OVA antibody responses in vivo. Overall, maintaining an appropriate surface charge is crucial for optimizing the adjuvant effect of cationic liposomes and enhancing the efficacy of liposome-based vaccines.

[Analysis on expression and molecular basis for ABO glycosyltransferase with dual specificity].

In order to elucidate the expression and molecular genetic background of ABO gene seven samples with ABO discrepancy further identified as bi-specific ABO gene were studied. All these samples were subjected to phenotyping by monoclonal and polyclonal antisera and were then genotyped by direct DNA sequencing and haplotype-sequencing at the exon 6 and 7 of ABO gene. As a result, six ABO dual-specific alleles were identified in Chinese population. An antigen expressed by these B (A) or Cis-AB individuals varied from very low level to the normal level, compared with common A blood group samples. In conclusion, molecular genetic backgrounds of two pairs out of four samples in all samples were the same, however, the ABO expression showed diverse.