Interleukin-37 ameliorates periodontitis development by inhibiting NLRP3 inflammasome activation and modulating M1/M2 macrophage polarization.

OBJECTIVE: Our study was designed to explore the role of IL-37 in M1/M2 macrophage polarization imbalance in the pathogenesis of periodontitis. BACKGROUND: Periodontitis is a chronic progressive inflammatory disease featured by gingival inflammation and alveolar bone resorption. Recent research has revealed that regulating macrophage polarization is a viable method to ameliorate periodontal inflammation. IL-37 is an anti-inflammatory cytokine, which has been reported to inhibit innate and adaptive immunity. METHODS: For in vitro experiment, mouse macrophage RAW264.7 cells were pretreated with 0.1 ng/mL recombinant human IL-37. M1 and M2 polarizations of RAW264.7 cells were induced by 100 ng/mL LPS and 20 ng/mL IL-4, respectively. The expression of M1 (iNOS, TNF-α, and IL-6) and M2 (CD206, Arg1, and IL-10) phenotype markers in RAW264.7 cells was detected by RT-qPCR, western blotting, and immunofluorescence staining. For in vivo experiment, experimental periodontitis mouse models were established by sterile silk ligation (5-0) around the bilateral maxillary second molar of mice for 1 week. H&E staining of the maxillary alveolar bone was used to show the resorption of root cementum and dentin. Alveolar bone loss in mouse models was evaluated through micro-CT analysis. The expression of iNOS and CD206 in gingival tissues was assessed by immunohistochemistry staining. NLRP3 inflammasome activation was confirmed by western blotting. RESULTS: IL-37 pretreatment reduced iNOS, TNF-α, and IL-6 expression in LPS-treated RAW264.7 cells but increased CD206, Arg1, and IL-10 in IL-4-treated RAW264.7 cells. LPS-induced upregulation in NLRP3, GSDMD, cleaved-IL-1ß, and cleaved-caspase-1 expression was antagonized by IL-37 treatment. In addition, IL-37 administration ameliorated the resorption of root cementum and dentin in periodontitis mouse models. IL-37 prominently decreased iNOS+ cell population but increased CD206+ cell population in gingival tissues of periodontitis mice. The enhancement in NLRP3, GSDMD, cleaved-IL-1ß, and cleaved-caspase-1 expression in the gingival tissues of periodontitis mice was offset by IL-37 administration. CONCLUSION: IL-37 prevents the progression of periodontitis by suppressing NLRP3 inflammasome activation and mediating M1/M2 macrophage polarization.

The non-coevolution of DIC and alkalinity and the CO2 degassing in a karst river affected by acid mine drainage in Southwest China.

Dissolved inorganic carbon (DIC) in mine water generated during coal mining is a large and potential source of atmospheric CO2, however its geochemical behaviors under the influence of AMD in relation to CO2 degassing and carbonate buffering are not well known. In this study, water temperature, pH, DO, alkalinity, Ca2+ concentration, and the carbon isotope of DIC were measured monthly from November 2020 to November 2021 and carbonate chemistry and CO2 emission flux were calculated to reveal the processes of DIC evolution and CO2 degassing from the Chetian River draining a karst region, which is materially affected by the input of large quantities of AMD. The results showed that carbonate erosion, the mineralization of terrestrial organic matter, and domestic sewage input are all identified to contribute DIC to different degrees to the river. Throughout the year, the Chetian River undergoes high-intensity CO2 degassing, which is dominated by HCO3--neutralized degassing and proton-enhanced degassing in different reaches. The pCO2 in the river under the influence of AMD is as high as 237,482 µatm, while the F-CO2 approaches 316.9 g C m-2 d-1. Meanwhile, the carbonate system in the downstream karst river buffers an average of 85.2 % of DIC release at the river's outlet. The input of AMD significantly altered the carbon cycle of the surface watershed in the headwaters of tributaries, and greatly enhanced the release of CO2 from surface water to the atmosphere; meanwhile, the buffering of carbonates on acidity in the water of main streams causes pCO2 to rapidly reduce over a short distance. Obviously, the carbon emission effect generated by the interaction between AMD and carbonate mainly occurs in the tributary water system. Considering the huge amount of AMD worldwide, this large potential source of atmospheric CO2 requires a specific and precise quantitative analysis based on actual observations.

The introduction of nitrogen from coal into the surface watershed nitrogen cycle due to coal mining activity.

Human activity has doubled the turnover rate of the terrestrial nitrogen cycle, leading to a series of environmental problems. A little-studied nitrogen source in terrestrial and aquatic environments is the nitrogen release associated with rock strata. Southwest China features the largest continuous karsts in the world, featuring a fragile ecological environment but abundant coal resources. The current study selected a typical coal mining area to evaluate the migration and transformation of nitrogen related to coal mining in surface watershed. The findings reveal that the total nitrogen in coal seams was as high as 10,162.3 mg/kg, mainly in the form of organic nitrogen, followed by NH4+-N, while the content of NO3--N was negligible. Based on the isotope fractionation and the co-evolution between Δ15NNO3-NH4 and δ15N-NO3-/δ15N-NH4+, coal mining changed the coal seams' oxidation-reduction state, resulting in the mineralization of organic nitrogen to NH4+-N. Next, NH4+-N gradually oxidized to NO3--N. Various forms of coal-origin nitrogen may be leached out by acid mine drainage (AMD), potentially contributing >10 % of NO3--N and 90 % of NH4+-N to the surface river. Another nitrogen source that requires serious consideration is the wide use of ammonium nitrate explosives in coal mining, as blasting residues may contribute about another 10 % to NO3--N in surface water. Since organic nitrogen accounts for >90 % of extractable nitrogen, the release of coal-origin nitrogen may contribute much more to the total nitrogen in surface water than to NO3--N. Based on the fractionation of nitrogen and oxygen isotopes of nitrate, low-pH AMD promotes the volatilization of nitrate in the form of nitric acid. The conversion of different forms of nitrogen in AMD will be the focus of future attention.

[Systematic comparison of two kinds of Bufonis Venenum derived from different Bufo gargarizans subspecies based on metabolomics and antitumor activity].

This paper compared the differences between two kinds of Bufonis Venenum produced by Bufo gargarizans gargarizans and B. gararizans andrewsi, and verified the rationality of the market value orientation of Bufonis Venenum based on the zebrafish mo-del. Twenty batches of Bufonis Venenum from Jiangsu province, Hebei province, Liaoning province, Jilin province, and Liangshan, Sichuan province, including B. gargarizans gargarizans and B. gararizans andrewsi, were collected. The UHPLC-LTQ-Orbitrap-MS combined with principal component analysis was used to compare the differences between two kinds of Bufonis Venenum. According to the limiting conditions of VIP>1, FC<0.5 or FC>2.0, and peak total area ratio>1%, 9 differential markers were determined, which were cinobufagin, cinobufotalin, arenobufagin, resibufogenin, scillaredin A, resibufagin, 3-(N-suberoylargininyl)-arenobufagin, 3-(N-suberoylargininyl)-marinobufagin, and 3-(N-suberoylargininyl)-resibufogenin. The content of 20 batches of Bufonis Venenum was determined according to the Chinese Pharmacopoeia(2020 edition) by high-performance liquid chromatography, and the 2 batches of Bufonis Venenum, CS7(8.99% of total content) and CS9(5.03% of total content), with the largest difference in the total content of the three quality control indexes of the Chinese Pharmacopoeia(bufalin, cinobufagin, and resibufogenin) were selected to evaluate their anti-liver tumor activity based on the zebrafish model. The tumor inhibition rates of the 2 batches were 38.06% and 45.29%, respectively, proving that only using the quality control indexes of the Chinese Pharmacopoeia as the value orientation of Bufonis Venenum market circulation was unreasonable. This research provides data support for the effective utilization of Bufonis Venenum resources and the establishment of a rational quality evaluation system of Bufonis Venenum.

The effects of weathering of coal-bearing stratum on the transport and transformation of DIC in karst watershed.

The mining of medium- to high­sulfur coal in karst areas has led to serious acidification problems in surface water, thus encouraging a re-evaluation of DIC transformation and CO2 source-sink relationships in karst watersheds. The weathering of limestone and sulfide-rich coal measures jointly influence the pH of the Huatan River in karst areas in Southwest China, which is lower in the rainy season and higher in the dry season. Due to CO2 degassing, DIC concentration tends to decrease along the flow direction, while δ13C-DIC gradually becomes heavier. In general, DIC transformation in the Huatan River is controlled by AMD input, CO2 degassing, organic matter (OM) degradation, and the dissolution and precipitation balance of carbonate minerals in different seasons. In spring, the mineralization of OM from terrestrial and domestic sewage gradually enhances and replenishes DIC in the water. As the pH increases in this season, the capacity for buffering CO2 increases. Meanwhile, OM degradation generates a large amount of CO2 in summer, and carbonic acid begins to dissolve limestone. In autumn, the pH decreases due to the enhanced weathering of sulfide-rich coal measures and the mass input of AMD. Thus, the river shows the ability to drive CO2 outgassing. In winter, CO2 degassing gradually weakens, DIC concentration is at its lowest, and δ13C-DIC reaches the heaviest value.

Heavy metal characteristics in porewater profiles, their benthic fluxes, and toxicity in cascade reservoirs of the Lancang River, China.

The construction of cascade reservoirs on the Lancang River (the upper Mekong) has an important influence on the distribution and accumulation of heavy metals. Heavy metal contents in porewater provide vital information about their bioavailability, studies on this aspect are rare until now. In this study, sediment cores were collected from four adjacent cascade reservoirs in the upper Mekong River to study the distribution, potential sources, diffusive fluxes and toxicity of heavy metals in porewater. The findings indicated that the average contents of Mn, Fe, As, Ni, Cu, Zn, Cd, and Pb in the sediment porewater were 6442, 644, 11.50, 2.62, 1.23, 3.95, 0.031, and 0.24 µg/L, respectively; these contents varied as the sediment depth increased. Correlation analysis and principal component analysis showed that Cu, Zn, Cd and Pb were mainly associated with anthropogenic sources, As, Mn and Fe were primarily affected by natural inputs, and Ni was affected by a combination of natural and anthropogenic effects. The diffusive fluxes of Mn, Fe, As, Ni, Cu, Zn, Cd, and Pb in the cascade reservoirs of the Lancang River were 919 - 35,022, 2.12 - 2881, 0.17 - 750, 0.71 - 7.70, 2.30 - 31.18, (-3.35) - 6.40, 0.06 - 0.54, and (-0.52) - 4.08 µg/(m2 day), respectively. The results of toxic units suggested that the contamination and toxicity of heavy metals in porewater were not serious. Overall, in the cascade reservoirs, the content and toxicity of heavy metals in porewater of the upstream reservoirs were higher than that of the downstream reservoirs. The operation of the cascade reservoirs enabled greater accumulation of contaminants in sediments of the upstream reservoirs. This research gives strong support for the prevention of heavy metal contamination and the sustainability of water resources under the running condition of cascade reservoirs on such a large international river (the Lancang-Mekong River).

Sulfur dynamics in forest soil profiles developed on granite under contrasting climate conditions.

Sulfur (S) dynamics in soils formed from granite remain poorly understood despite its importance as an essential plant macronutrient and component of soil organic matter. We used stable S isotope ratios to trace the sources and biogeochemical processes of S in four forest soil profiles developed on granite under contrasting climate conditions. The soil S is derived mainly from decomposing litter; no significant geogenic contribution to its content is noted as a result of the low S concentration of the granite (~ 5 µg/g). Colder/drier climate results in high organic S retention at the surface due to weak mineralization of organic S. Although warmer/wetter climate increases the S mineralization and leaching loss, SO42- adsorption is an important S retention process in the subsurface. The vertical distribution of S isotope compositions in the soil profiles across the four sites indicates (i) a downward increase in δ34S values in the upper profiles due to continuous mineralization of organic S with an occasional decrease in δ34S values in the subsurface due to dissimilatory sulfate reduction (DSR), (ii) constantly high δ34S values in the middle profiles due to the low water permeability, and (iii) a downward decrease in δ34S values in the low profiles due to increased contribution of bedrock with depth. Regardless of the variation in soil depth and climate, the total S concentration is proportional to the pedogenic Fe/Al minerals, suggesting the important role of secondary Fe/Al minerals in retaining S in soils. This study provides an integration and synthesis of controls of climatic and edaphic variables on S dynamics in forest soil profiles developed on granite.

Diel variation of CH4 emission fluxes in a small artificial lake: Toward more accurate methods of observation.

Lakes are significant sources in global methane (CH4) budgets. However, estimations of the magnitude of global CH4 emissions from lakes may be highly biased owing to the uncertainties in data originating from observation times, methods, and parameterizations of the gas transfer velocity (k). Here, we conducted continuous 48-hour measurements of CH4 fluxes using the floating chamber method seasonally at Lake Baihua, a small reservoir in southwestern China, and compared the results with estimates derived from boundary layer models. Results showed that there was a weak dependency of k on wind speed, indicating that wind speed was not the major factor regulating gas exchange in such small lakes. It is thus concluded that the wind speed-dependent boundary layer model method is not suitable for CH4 flux observations in small and medium-sized lake, and that the floating chamber method is recommended for use instead. The measured CH4 fluxes displayed remarkably diurnal patterns, therefore the use of single observations to represent daily average values comes with unacceptably large uncertainties. A reasonable alternative is averaging observations made at sunrise and at sunset to represent daily values, which has a much smaller uncertainty (ranging from 0.8% to 13.6%). The coincident peaks of CH4 and chlorophyll concentrations in the subsurface indicate that CH4 originated mainly from aerobic methanogenesis. Solar radiation is likely one of the major factors regulating CH4 production and emissions in the lake through enhancing CH4 production, inhibiting CH4 oxidation, and probably changing hydrodynamics conditions. Therefore, irradiation should be taken into consideration as a key factor in observing CH4 fluxes in lakes. As sampling times are limited, observations during both sunny and cloudy weather should be proportionally included. This is the first time, to the best of our knowledge, that solar radiation has been proposed as a key driver of CH4 emissions from lakes.

Quercetin suppresses apoptosis of chondrocytes induced by IL-1ß via inactivation of p38 MAPK signaling pathway.

The objective of the present study was to investigate the effect of quercetin and evaluate its protective effect on articular cartilage in patients with osteoarthritis (OA), by intervening the p38 pathway. The target factors of quercetin protecting articular cartilage in patients with OA were predicted scientifically and analyzed to predict the possible pathways by using network pharmacology. A pathway predicted to be closely associated with osteoarthritis was chosen for experimental verification in in vitro cells. The optimal intervention drug concentrations were selected by the of Cell Cycle Kit-8 assay, osteoarthritis and inflammatory factors relevant to osteoarthritis, interleukin-1ß and tumor necrosis factor-α, were tested by of enzyme-linked immunosorbent assay, and the expression of relevant proteins and mRNA of the p38 signaling pathway was tested by reverse transcription-quantitative PCR and western blotting, following quercetin intervention. It was found that quercetin, at the concentration of 100 umol/l, can decrease inflammatory factors relevant to OA, inhibit the expression of p38, matrix metalloprotease 13 and ADAMTS in the pathway, and promote the expression of collagen Ⅱ. Therefore, it is postulated that quercetin can lower the expression of inflammatory factors in cartilage for the prevention and treatment of OA, and the expression level of relevant factors can be changed positively by blocking the p38 MAPK signaling pathway. Thus, quercetin can promote the repair of degenerative chondrocytes and protect articular chondrocytes.

Efficacy and safety of intra-articular injection of mesenchymal stem cells in the treatment of knee osteoarthritis: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the effects and safety of intra-articular injection of mesenchymal stem cells on patients with knee osteoarthritis by a systematic review and meta-analysis. METHODS: PubMed, EMBASE, and Cochrane Library were retrieved. An assessment of the risk of bias was done through the Cochrane Collaborative Bias Risk Tool, publication bias was assessed by plotting funnel plots and Egger tests. Pain and functional improvements in patients with knee osteoarthritis were determined by changes in VAS scores and WOMAC scores at baseline and follow-up endpoints. For the evaluation of MRI, the WORMS score and changes in cartilage volume were used. In addition, the number of adverse events in the intervention group and the control group were counted to explore the safety. RESULTS: A total of 10 randomized controlled trials involving 335 patients were included. In the pooled analysis, compared with the control groups, the VAS scores of MSC groups decreased significantly (MD,-19.24; 95% CI: -26.31 to -12.18, P < .00001. All of the WOMAC scores also improved significantly: the total scores (SMD, - 0.66; 95% CI: - 1.09 to -0.23, P = .003), pain scores (SMD, - 0.46; 95% CI: - 0.75 to -0.17, P = .002), stiffness scores (SMD, -0.32; 95% CI: -0.64 to 0.00 P = 0.05), and functional scores (SMD, -0.36; 95% CI: -0.69 to -0.04, P = .03). Two studies with non-double-blind designs were the main source of heterogeneity. In terms of cartilage repair, there was no significant difference in the WORMS score, but there was a significant increase in cartilage volume in the MSC group (SMD, 0.69; 95% CI: 0.25 to 1.13, P = .002). The proportion of patients with adverse events in the MSCs treatment group was significantly higher than that in the control group (OR, 3.20; 95% CI: 1.50 to 6.83, P = .003). CONCLUSIONS: Intra-articular injection of mesenchymal stem cells is effective and safety to relieve pain and improve motor function of patients with knee osteoarthritis in a short term which is different to conclusions of previous study.

The effect of curcuminoids for treating knee osteoarthritis: A protocol for systematic review and meta analysis.

BACKGROUND: Knee osteoarthritis (KOA) is 1 of the commonest cause of disability with joint pain in adults and a burden on healthcare resources. The limitations of current KOA treatment necessitate further researches to discover the more efficacious and safety treatments. There are increasing clinical studies investigating the potential protective effects of Curcuminoids in the alleviation of symptoms in patients suffering from KOA. However, the convincing evidence indicating the efficacy of curcuminoids for patients suffering from KOA remains unclear. METHODS: Several databases including PubMed, Web of Science, Cochrane Library, Embase, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, and Wanfang Database will be searched. And the language was not limited. We will include all Randomized controlled trials that use curcuminoids to treat patients with KOA, regardless of blinding. If the pre-crossover data can be analyzed to avoid carryover effects, the crossover randomized trials also are included. Meanwhile, We will exclude non-randomized controlled trials, qualitative studies, uncontrolled clinical trials and laboratory studies. The primary end point include Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale scores and Lequesne's pain functional index. The secondary end points are total effective rate and adverse effects. The Review Manager Version 5.3 will be used to perform the data synthesis and subgroup analysis. DISCUSSION: There are evidences that supports the potential protective effects of Curcuminoids in the alleviation of symptoms in patients suffering from KOA. This systematic review and meta-analysis would provide convincing evidence indicating that curcuminoids relieve the symptoms of patients suffering from KOA. REGISTRATION: Open Science Framework (OSF) registries (https://osf.io/fz29b) with the registration DOI: 10.17605/OSF.IO/FZ29B.

A novel surgical method for treating medial-end clavicle fractures.

The present study examined the effectiveness of the method of inversing the distal clavicle anatomic locking plate to treat medial-end clavicle fractures. This involved retrospectively analyzing six cases of medial-end clavicle fractures treated using the method of inversing the distal clavicle anatomic locking plate between September 2013 and December 2015. These cases included five men and one woman with an average age of 46.3±10.6 years old and a range of 24-66 years old. Among these cases, one was type A, two were type C, and three were type D, based on the Throckmorton type classification. All patients had fresh closed fractures, which were caused by direct injury. A regular postoperative follow-up was performed and the therapeutic efficacy was evaluated systematically with reference to the Rockwood and Disability of the Arm, Shoulder and Hand (DASH) score standards. All six cases had a follow-up visit, which was between 10 and 14 months with an average of 12.0±2.2 months. All patients exhibited osseous healing and functional recovery without incision infection, nerve vascular injury, chest injury, fracture nonunion, or other complications. According to the Rockwood and DASH score standards, evaluation of the curative effect showed that five cases were excellent and one case was good, and the associated rate for achieving good or excellent outcomes was 100%. All of the DASH scores were <10. These results indicated that the effect of the treatment of medial-end clavicle fractures by the method of inversing the distal clavicle anatomic locking plate was reliable, and the functional recovery of patients was good, making this method worthy of clinical promotion.

The promising indicators of the thermal and mechanical properties of collagen from bass and tilapia: synergistic effects of hydroxyproline and cysteine.

Collagen has been widely documented as one of the most promising and competitive biomaterials for tissue engineering and medical applications. However, the properties of collagen differ from one source to another. In the present study, type I collagen (COL-I) was extracted and purified from the skins of Japanese sea bass (Lateolabrax japonicus) and Nile tilapia (Oreochromis niloticus). Ultraviolet (UV) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE were performed to characterize both COL-Is. The denaturing temperature of bass collagen (BC) was observed to be 27.2 °C, and 35.3 °C for tilapia collagen (TC). The content of hydroxyproline was 13.4% in TC, which was similar to that in porcine collagen (PC, 13.6%) and higher than that in BC (10.3%), while the content of cysteine in TC (0.87%) was significantly higher than that in PC (0.04%) and BC (0.35%). After incubation at different temperatures for 9 h, more degraded collagen bands appeared in the BC hydrogel (BCH) group than in the TC hydrogel (TCH) group, indicating that TCH exhibited better thermal stability than BCH. The thermal stabilities of TCH and PC hydrogel (PCH) were similar. The compressive stress of TCH was up to 0.099 MPa, while it was 0.047 MPa for BCH and 0.003 MPa for PCH. These results demonstrated that the content of amino acids (especially hydroxyproline and cysteine) has a synergistic effect on the thermal and mechanical properties of BCH, TCH and PCH, which would be an indicator of the thermal and mechanical properties of collagen hydrogels in future studies.

Nitrate dynamics during impoundment and flood periods in a subtropical karst reservoir: Hongfeng Lake, Southwestern China.

Nitrogenous species, particularly nitrate, are some of the most significant contaminants in freshwater rivers and lakes in China, posing a significant threat to human and ecosystem health. To identify the major nitrate sources and transformation processes in a subtropical karst lake (Hongfeng, HF) in Southwest China, two sampling campaigns involving three lake profiles were conducted during the impoundment period (April) and flood period (August). Hydro-chemistry parameters, concentration of nitrogenous species, and dual isotopes of nitrate were analyzed. Nitrate was the major nitrogenous species in HF lake with higher proportion in April than August. The concentrations of NH4+, NO2- and dissolved organic nitrogen were below the detection limit in April, while NH4+ increased with depth in August, which may be a result of mineralization. Nitrification was detected during the impoundment period and from the surface to a depth of 10 m during the flood period. Denitrification was detected in the lake bottom waters during the flood period with isotopic fractionation of -10.7‰ for δ15N-NO3- and -4.7‰ for δ18O-NO3-. The Rayleigh distillation demonstrated denitrification showed spatial variation (53% and 89% of nitrate in the southern and northern region of the lake, respectively). The Bayesian modelling results suggest that organic nitrogen degradation and sediment make the largest contributions to nitrate (51% and 38% in April and 33% and 24% in August, respectively) to the lake. Tributaries contributed more nitrate in August (37%) than in April (10%). The results highlight that modified endogenous nitrogen contributed a high proportion of nitrate sources within the lake system during the two periods.

Microbial production of amino acid-modified spider dragline silk protein with intensively improved mechanical properties.

Spider dragline silk is a remarkably strong fiber with impressive mechanical properties, which were thought to result from the specific structures of the underlying proteins and their molecular size. In this study, silk protein 11R26 from the dragline silk protein of Nephila clavipes was used to analyze the potential effects of the special amino acids on the function of 11R26. Three protein derivatives, ZF4, ZF5, and ZF6, were obtained by site-directed mutagenesis, based on the sequence of 11R26, and among these derivatives, serine was replaced with cysteine, isoleucine, and arginine, respectively. After these were expressed and purified, the mechanical performance of the fibers derived from the four proteins was tested. Both hardness and average elastic modulus of ZF4 fiber increased 2.2 times compared with those of 11R26. The number of disulfide bonds in ZF4 protein was 4.67 times that of 11R26, which implied that disulfide bonds outside the poly-Ala region affect the mechanical properties of spider silk more efficiently. The results indicated that the mechanical performances of spider silk proteins with small molecular size can be enhanced by modification of the amino acids residues. Our research not only has shown the feasibility of large-scale production of spider silk proteins but also provides valuable information for protein rational design.

The marriage of endo-cavity and exo-wall complexation provides a facile strategy for supramolecular polymerization.

Butylated pillar[5]arene (1) and N,N'-bis(n-butyl)pyromellitic diimide (2) form a 2 : 1 sandwich-type complex external to the walls of the receptor ("exo-wall" complex). The marriage of exo-wall interactions and endo-cavity inclusion provides a new strategy for the construction of supramolecular polymers from unfunctionalized neutral receptors.

Biphen[n]arenes.

To design and exploit novel macrocyclic synthetic receptors is a permanent and challenging topic in supramolecular chemistry. Here we describe the one-pot synthesis, unique geometries and intriguing host-guest properties of a new class of supramolecular macrocycles - biphen[n]arenes (n = 3, 4), which are made up of 4,4'-biphenol or 4,4'-biphenol ether units linked by methylene bridges at the 3- and 3'- positions. The biphenarene macrocycles are conveniently accessible/modifiable and extremely guest-friendly. Particularly, biphen[4]arene is capable of forming inclusion complexes with not only organic cationic guests but also neutral π-electron deficient molecules. Compared with calixarenes, resorcinarenes, cyclotriveratrylenes and pillararenes with substituted mono-benzene units, the biphen[n]arenes reported here possess significantly different characteristics in both their topologic structures and their recognition properties, and thus can find broad applications in supramolecular chemistry and other areas.

Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate.

Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Гmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (DG0 m, DH0 m and DS0 m) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process.

Study of the formation and solution properties of worm-like micelles formed using both N-hexadecyl-N-methylpiperidinium bromide-based cationic surfactant and anionic surfactant.

The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB) with the anionic surfactant sodium laurate (SL) in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles.

Short-term field observations of nitrous oxide saturations in Lake Taihu, China: the need for high temporal resolution studies.

The incomplete understanding of the processes which control aquatic nitrous oxide (N2O) production is partially due to a lack of onsite data with which to describe the temporal resolution of N2O production. To help resolve this, we directly measured the N2O saturation (relative to atmospheric partial pressure) on an hourly basis over two survey periods (July and September 2003) in Lake Taihu, a large eutrophic lake in eastern China. July N2O saturations displayed a distinct diurnal pattern, opposite to those observed by others in subtropical streams, but similar to N2O emissions observed from incubated estuarine sediments. Correlative analyses indicate that biogeochemical processes operate as important controls on N2O production over very short time scales. Nitrous oxide production processes are not only regulated by O2 dynamics related to microalgal photosynthesis, but also closely related to organic matter decay at the sediment-water interface. While large-scale changes (approximately 25-fold) in N2O fluxes in Lake Taihu are a function of variable N loading, biogeochemical processes concerning O2 and N transformation at the sediment-water interface have significant (-twofold) impacts on the regulation of N2O production over very short time scales. Further, high temporal resolution research focused on developing a comprehensive understanding of lacustrine N2O production, including natural and anthropogenic loading and biogeochemical transformation processes, is clearly needed.