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A cost-effective and efficient system of ureas/organic bases toward the controlled self-switchable copolymerization of epoxide/PA/CL to obtain well-defined triblock polyesters.

The suspended particulate matter (SPM) is an important carrier of heavy metals transportation from land to sea, so it is significant to study the heavy metal pollution in SPM. The distribution and assessment of five heavy metals (Mn, Cr, Ni, Cu, and Pb) in SPM collected from Passur River and its estuary in Sundarban were studied in combination with water temperature, salinity, and turbidity. The results show that the heavy metal content and distribution in SPM are mainly controlled by runoff input, hydrodynamic process and the interaction process of salt and fresh water in estuaries. The quality evaluation results of heavy metals in SPM show that pollution degree is light. Studies on the heavy metals in SPM are of great significance to comprehensively evaluate regional pollution status and carry out early warning.

A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of bio-based cyclohexane oxide (CHO)/propylene oxide (PO)/phthalic anhydride (PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 °C to 133 °C. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability (T5% ranging from 306 °C to 323 °C) and high tensile strength (40.21–55.7 MPa) that is comparable with polystyrene (PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.

Aliphatic polyesters and polycarbonates such as polylactide (PLA), polycaprolactone (PCL) and poly(propylene carbonate) (PPC), are well known as biodegradable, biocompatible and environmental-friendly polymeric materials, which have been widely used in various areas ranging from packaging to biomedical materials. The production and usage of biodegradable plastics can greatly alleviate the safety and environmental concerns because of the fairly short degradation periods and low toxicity of catabolite. During the degradation process of polymers, obvious changes appear in polymer structures and the physiochemical properties. Therefore, it is necessary to regulate and control the degradation behaviors and periods of biodegradable plastics such as polyesters and polycarbonates, which is significant for their more widespread popularization and applications. In this context, it is highly desirable to make a review contribution in this field so as to better understand the recent research progress on polymer degradation behaviors and kinetics, as well as the future prospect of biodegradable polymers. Herein, this paper reviews the research progress on the degradation behaviors of biodegradable polyesters and polycarbonates materials including PLA, PCL and PPC. Through an in-depth study of various internal/external factors, the degradation mechanism of these polymers is unraveled, which will motivate future studies into the synthesis of novel biodegradable polymers and the understanding of their degradation behavior on the molecular level.

A novel, efficient and durable ZrP@PDA/Ag nanocatalyst was prepared via the facile reduction and deposition of silver nanoparticles (AgNPs) on two dimensional (2D) α-zirconium phosphate (ZrP) nanosheets using bio-inspired dopamine chemistry. The formation, adhesion and dispersion of AgNPs were confirmed by the full morphological and structural characterizations including SEM, TEM, FTIR, TGA, WXRD, and XPS. This ZrP@PDA/Ag nanocatalyst was evaluated by the reduction of 4-nitrophenol into 4-aminophenol, utilizing UV-vis absorption spectroscopy to monitor the reaction solution with a trace silver content of 0.125 μg mL−1. ZrP@PDA/Ag exhibits a superior catalytic activity compared with other noble metal nanocatalysts due to its high turnover frequency of 32.36 min−1 at room temperature without stirring, which is as high as almost 10 times that of the reported nanocatalysts using 2D graphene and silica supports. Furthermore, due to the excellent catalytic recyclability of ZrP@PDA/Ag it has very promising prospects in the treatment of organic pollutants in water.

Supported nano-silver composites, famous for large specific surface area, good dispersibility and high catalytic activity, have been widely used in chemistry and chemical engineering, biomedicine and new materials. In this paper, we report recent research progress on supported nano-silver composites as reviewed from preparation techniques (chemical reduction, physical reduction and in-situ formation), types of supporters (organic and inorganic) and anti-microbial/catalytic activity. Firstly, the principles and merits/demerits of three preparation techniques for silver nanoparticles are elaborated. Afterwards, preparation, structures and properties of supported nano-silver composites are summarized through different types of supporters, as well as their applications in catalytic reaction, pollutant control and antimicrobial. Furthermore, it has been demonstrated that silver nanoparticles produced by in-situ formation are more stable and well-distributed, readily meeting the demands for practical applications. Finally, superior supporters for nano-silver composites should be of high specific surface area and good stability, non-expensive, environmentally friendly and low-toxicity.

Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety, environmental friendliness, and low cost. However, the freezing of aqueous electrolytes limits the normal operation of batteries at low temperatures. Herein, a series of high-performance and low-cost chloride hydrogel electrolytes with high concentrations and low freezing points are developed. The electrochemical windows of the chloride hydrogel electrolytes are enlarged by > 1 V under cryogenic conditions due to the obvious evolution of hydrogen bonds, which highly facilitates the operation of electrolytes at ultralow temperatures, as evidenced by the low-temperature Raman spectroscopy and linear scanning voltammetry. Based on the Hofmeister effect, the hydrogen-bond network of the cooperative chloride hydrogel electrolyte comprising 3 M ZnCl2 and 6 M LiCl can be strongly interrupted, thus exhibiting a sufficient ionic conductivity of 1.14 mS cm−1 and a low activation energy of 0.21 eV at −50 °C. This superior electrolyte endows a polyaniline/Zn battery with a remarkable discharge specific capacity of 96.5 mAh g−1 at −50 °C, while the capacity retention remains ~ 100% after 2000 cycles. These results will broaden the basic understanding of chloride hydrogel electrolytes and provide new insights into the development of ultralow-temperature aqueous batteries.

The shortage of powerful functionalities on scalable α-zirconium phosphate (ZrP) materials blocks the facile preparation of highly dispersed and immobilized metal nanocatalysts. We herein present a mild and facile mussel-inspired strategy based on polydopamine (PDA) for the surface modification of ZrP, and hence, the generation of powerful functionalities at a high density for the straightforward reduction of chloroauric acid to Au nanoparticles (AuNPs) and the immobilization of AuNPs. The resulting ternary ZrP@PDA/Au exhibited ultra-small AuNPs with a particle size of around 6.5 nm, as estimated based on TEM images. Consequently, the ZrP@PDA/Au catalyst showed significant activity in the catalytic conversion of 4-nitrophenol (4NP) to 4-aminophenol (4AP), a critical transformation reaction in turning the hazard into valuable intermediates for drug synthesis. The PDA was demonstrated to play a critical role in the fabrication of the highly efficient ZrP@PDA/Au catalyst, far outperforming the ZrP/Au counterpart. The turnover frequency (TOF) achieved by the ZrP@PDA/Au reached as high as 38.10 min−1, much higher than some reported noble metal-based catalysts. In addition, the ZrP@PDA/Au showed high stability and reusability, of which the catalytic efficiency was not significantly degraded after prolonged storage in solution.

Immobilized catalysis integrates the advantages of both homogeneous and heterogeneous catalyst systems and thus has attracted high attention. Herein, we report the synthesis of a novel immobilized ...

The biogenic silica of sediment samples from Core CJ01-185 which is collected from the eastern India Ocean off the Sunda Strait is analyzed to evaluate the impact of the opening of the Sunda Strait on a paleoproductivity evolution. The new results indicate that the biogenic silica mass values of Core CJ01-185 show the lowest 0.86% in the last glacial period, and reach its maxima of 1.89% in the late Holocene. Furthermore, the biogenic silica mass accumulation rate (MARBSi) values also vary with much higher during the late Holocene than during the last glaciation. The input of additional terrigenous materials from the Java Sea has enhanced the paleoproductivity and increased the biogenic silica mass and MARBSi values after the opening of the Sunda Strait. It is suggested that the paleoproductivity in the study area is mainly influenced by the southeast monsoon and upwelling before the opening of the Sunda Strait. However, the paleoproductivity is dominated by the terrigenous materials input other than by the southeast monsoon or upwelling in the Holocene.

We disclose an economical and metal-free catalyst system of (thio)ureas/organic bases for effective fully alternating copolymerization of epoxides and anhydrides, which remains a challenge in sustainable polyester synthesis. A series of commercial (thio)ureas and organic bases were employed as dual catalysts to optimize the activity, and the results indicate that the (thio)ureas with higher basicity paired with quaternary onium salts show higher activity. Particularly, the U1/PPNCl pair shows extremely high TOF (456 h−1) toward the ring-opening alternating copolymerization of cyclohexane oxide with phthalic anhydride, which is comparable to the activity of metal-based complex catalysts. Structurally diverse polyesters with high ester linkages (99%) and various glass transition temperatures (ranging from −8 to 133 °C) can be obtained by coupling of various renewable epoxides and anhydrides. What's more, structural analysis of the resultant polymers and the interactions between the monomers and the dual catalysts confirmed by 1H NMR reveal that the (thio)urea can act as a bifunctional catalyst, which activates both the initiating chain end and the monomer through H-bonding in the (thio)urea/PPNCl catalyst system, resulting in high activity.

The concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Al in suspended particles were measured, and temperature, salinity, flow velocity and direction during a tidal cycle were observed before and after Typhoon Fung-wong at six stations in Quanzhou Bay, respectively. The comparison results show that, after the typhoon, the salinity in Quanzhou Bay decreased, whereas the concentrations of heavy metals increased by a factor of between 2 and 10, and the high heavy metal concentration corresponded to the low value of ratio between heavy metals and Al (HMs/Al), suggesting that these increased heavy metals were mainly from natural sources. Instantaneous unit width flux calculations for heavy metals at different stations indicate that sediments are an important source of heavy metals in suspended particles under the influence of typhoon, which has significantly contribution to understanding the impact of typhoons on the heavy metal pollution in the coastal area.

Hydrogels and polydimethylsiloxane (PDMS) are complementary to each other, since the hydrophobic PDMS provides a more stable and rigid substrate, while the water-rich hydrogel possesses remarkable hydrophilicity, biocompatibility, and similarity to biological tissues. Herein a transparent and stretchable covalently bonded PDMS-hydrogel bilayer (PHB) structure is prepared via in situ free radical copolymerization of acrylamide and allylamine-exfoliated-ZrP (AA-e-ZrP) on a functionalized PDMS surface. The AA-e-ZrP serves as cross-linking nano-patches in the polymer gel network. The covalently bonded structure is constructed through the addition reaction of vinyl groups of PDMS surface and monomers, obtaining a strong interfacial adhesion between the PDMS and the hydrogel. A mechanical-responsive wrinkle surface, which exhibs transparency change mechanochromism, is created via introducing a cross-linked polyvinyl alcohol film atop the PHB structure. A finite element model is implemented to simulate the wrinkle formation process. The implication of the present finding for the interfacial design of the PHB and PDMS-hydrogel-PVA trilayer (PHPT) structures is discussed.

Since toxic gas leakage may cause ecological environmental problems and even life-threatening damage, effective monitoring of toxic gas is of great importance and subject to increasing demand. However, complicated environmental factors, as well as various coexisting interferences can easily affect the sensitivity and selectivity of gas sensors, hindering their performance. Recent reports have successfully demonstrated the development of hierarchical nanostructures with desirable self-cleaning properties, yet gas sensors that can resist contamination have rarely been realized. Here, we developed a reentrant thorny ZnO/graphene hybrid nanowall structure that simultaneously repels liquid contamination and possesses NH

Total organic carbon (TOC), total nitrogen (TN), δ13Corg, δ15N, and grain size were measured in two sediment cores from reserves adjacent to Dongshan Bay, China. The aims were to identify organic matter (OM) sources and to evaluate the combined impact of human activity and natural environmental processes over the last ∼100 yr. In a coral reserve far from the estuary of Zhangjiang River, the average sediment accumulation rate (SAR) was 0.51 cm/yr from ca. 1839–2015, and the values of δ13Corg and C/N (atomic ratio of TOC to total N) ranged from −21.9‰ to −23.7‰ and from 5.7 to 8.1, respectively. In a mangrove forest reserve near the estuary, SAR averaged 0.49 cm/yr from ca. 1891–1985 and 2.41 cm/yr from ca. 1985–2015, and the δ13Corg and C/N values ranged from −22.7‰ to −26.3‰ and from 9.3 to 21.7, respectively. By combining a comparison plot of C/N and δ13Corg and a binary mixing model (based on δ13Corg and Norg/Corg, respectively), the major OM sources were assigned and their sedimentary contributions estimated. The sedimentary OM in the coral reserve had mainly an offshore marine authigenic signature with an average terrigenous contribution of 56%. While input from the Zhangjiang River declined from the 1980 s, urban development, deforestation and land reclamation contributed to an overall increase in the total mass accumulation rate (MAR). The coral was also severely damaged by the advent of poaching around the same time. These two factors collectively resulted in a rapid decrease in OM content and OC accumulation rate (CARorg) of the sediments until the establishment of the coral reserve in 1997. Changes in terrain and climate and the construction of water conservancy facilities were traditionally the primary factors responsible for changes in the sedimentary environment of the mangrove forest reserve. Since the 1980s, however, the expansion of the mangrove forest along with human activity has led to rapid increases in MAR and CARorg; while, protective measures and a favorable climate have also promoted the growth of the mangrove forest.

Coastal embayments play a vital role in the global carbon cycle either as sources of organic matter to open sea or as carbon sinks due to the accumulation of organic matter in sediments. This paper describes a study of Luoyuan Bay, a typical semi-enclosed embayment with a total area of approximately 227 km 2 in a strong tidal environment. The analysed results indicate that the particulate organic carbon (POC) concentration in suspended particulate matter (SPM) varies from 0.57 mg/L to 1.33 mg/L at the bottom layer (0.5 MAB, meters above bed) and from 0.54 mg/L to 1.25 mg/L at the surface layer (0.5 MBS, meters below surface). The δ 13 C‰ ranges from −25.52‰ to −23.54‰ and exhibits different variations at the surface and bottom layers in spring and neap tides. The POC content in deposited particulate matter (DPM) varies from 0.62% to 2.95%, increasing from spring to neap tide, and the δ 13 C and C/N molar ratio are −25.29‰ ∼ −21.41‰ and 4.18–8.53, respectively. The settling fluxes of POC obtained by sediment trap decrease from 2.25 g/m 2 ·tide during the spring tide to 0.55 g/m 2 ·tide during the neap tide with a mean value of 1.41 g/m 2 ·tide during the observation, whereas the settling flux of SPM decreases from 456.76 g/m 2 ·tide during the spring tide to 37.12 g/m 2 ·tide during the neap tide. Combining the δ 13 C and C/N molar ratio, three end-members are recognized, i.e., freshwater algae and phytoplankton, marine algae and phytoplankton, and kelp-derived detritus. The mean contribution to POC from these three sources is 57.2%, 31.8% and 11.0% in SPM, and 39.9%, 35.0% and 25.1% in DPM, respectively. The POC from freshwater algae, phytoplankton and kelp-derived detritus is controlled by sediment dynamic processes.

Bamboo charcoal (BC) shows similar structure and property to the onion fullerene carbon and carbon nanotubes with hierarchical porous, microporous tunnel structure and good electrical conductivity. By simple treatment, a carbon substrate material with good electrochemical properties can be obtained. Monodispersed rice-like Fe2O3 supported by modified bamboo charcoal (MBC) are prepared via a facile precipitation of FeOOH anchored on carbon charcoal substrate combined with a high temperature calcination. The SEM results show that rice-like Fe2O3 uniformly anchored on hierarchical porous carbon-based microscopic structure with a size distribution between 80 and 100 nm. In addition, the hybrids exhibit good lithium storage property as anode materials. MBC shows stable cycle performance and the reversible capacity can still be maintained at 327 mAh g−1 after 150 cycles under 200 mA g−1. When incorporated with rice-like Fe2O3, the composite delivered a specific capacity of 1094 mAh g−1 after150 cycles at 200 mA g−1 and a high capacity of 765 mAh g−1 even at 1600 mA g−1.

Production of biodegradable plastics from carbon dioxide, particularly as a means of recycling industrial waste gas, is a promising advancement in environmental and energy conservation. Recent research and development on CO2-based copolymers has demonstrated new approaches to achieve improvements of thermal and mechanical properties, and extension of functionalization, and practical applications. CO2-based plastics may soon become commercially accessible as a new class of environmentally-friendly, energy-saving and biomedical polymeric materials.

The isothermal and nonisothermal crystallization behaviors of poly(e-caprolactone) and poly(caprolactone-co-cyclohexene carbonate) were investigated utilizing differential scanning calorimeter and ...

The settling of particulate organic carbon is significant for the vertical transfer and burial of organic carbon. Using time-series sediment traps, we collected settling particulate matter in the near-bottom layer (8 mab [meters above bed]) over eight continuous days in the continental shelf waters of the northern Taiwan Strait and analyzed the particulate organic carbon content. The observational results indicated that the deposition flux in the continental shelf waters during the summer in the north-eastern Taiwan Strait is 0.86 g/m 2 ·d ∼10.68 g/m 2 ·d; the corrected deposition flux is lower than the measured value by approximately 4.5%–30.6%. The particulate organic carbon (POC) content and δ 13 C org ‰ value are 0.589%–0.741% and −20.74‰∼−22.61‰. The δ 13 C org ‰ indicated that the settling particulate matter was primarily from marine sources at a contribution rate of 70%–88%. Settling particulate matter primarily came from the re-suspension of bottom sediment which accounted for 65%–85% of settling particulate matter. The rising thermocline and halocline near the bottom can strengthen the contribution of re-suspension to the settling particulate organic carbon.

Conventional liquid electrolytes applied in lithium-ion batteries suffer from high flammability, lithium dendrites and leakage. Gel polymer electrolytes (GPEs) are promising alternative electrolytes owing to their high ionic conductivities and enhanced safeties. Nevertheless, the flammable plasticizers of GPEs still bring safety hazards for the batteries. To address these issues, nonflammable highly-fluorinated quasi-solid-state polymer electrolytes (ED@PVDF) with ultrahigh ionic conductivities, excellent flame-retardant properties and superior cycling stability are developed. ED@PVDF possesses three-dimensional polymeric network within the framework of electrospun PVDF fibers, which is fabricated by thiol-ene click reaction. Highly-fluorinated carbonates (fluoroethylene carbonate and methyl 2,2,2-trifluoroethyl carbonate) are employed as plasticizers for ED@PVDF to improve flame-retardant property and enhance compatibility with anodes. Nonflammable ED@PVDF exhibits remarkable flame resistance, the highest ionic conductivity (4.41 mS cm−1 at 30 °C) among the nonflammable polymer electrolytes and wide electrochemical windows (5.6 V). ED@PVDF can promote the generation of LiF-rich solid electrolyte interphase and effectively restrain dendrite growth on Li metal anodes. ED@PVDF endows LiFePO4 cells with outstanding rate capability (specific capacity of 123.8 mAh g−1 at 5C rate) and superior cycling stability (capacity retention of 81.4% over 1000 cycles).

With sea level rise in the early Holocene, the warm and low-salinity sea water from the Java Sea was transported into the eastern Indian Ocean after the opening of the Sunda Strait. However, the impact of this process on sediment provenance and paleoproductivity is rarely known. In this study, we analyzed the grain size, Sr-Nd-Pb isotopic compositions and biogenic elements of core CJ01-185 (1538 m water depth) in the eastern Indian Ocean off the Sunda Strait. Our new results reveal a large volcanic eruption in the west of Java at 2.1 ka, and the Krakatau eruption at 1883 CE. On the basis of the Pb isotopic compositions, 87 Sr/ 86 Sr ratios, and e Nd values, we infer that sediments from core CJ01-185 were derived primarily from Java Island. There is a distinct change in Sr-Nd-Pb isotopic compositions of the sediments from the last glacial period to the Holocene, indicating less radiogenic Nd isotopes from the Java Sea into the eastern Indian Ocean after the opening of the Sunda Strait at ∼10 ka. Moreover, the sedimentation rate increased significantly from 6.5 cm kyr −1 during the last glacial period to 20 cm kyr −1 in the Holocene. The input of additional terrigenous nutrients from the Java Sea induced paleoproductivity with higher TOC and TN concentrations after the opening of the Sunda Strait. Our results thus suggest that the paleoproductivity was mainly influenced by terrigenous materials input in the Holocene, other than southeast monsoon or upwelling in the last glacial period.

The geochemical compositions of sediments in the Dongshan Bay, a semi-enclosed bay on the southeast coast of China, were obtained to identify pollutant sources and evaluate the anthropogenic impacts over the last 100 years. The results indicated that the metal flux had been increasing since the 1980s. Enrichment factor values (Pb, Zn and Cu) suggested only slight enrichment. The proportion of anthropogenic Pb changed from 9% to 15% during 2000-2014. Coal combustion might be an important contamination source in the Dongshan Bay. The historical variation in the metal flux reflected the economic development and urbanization in the Zhangjiang drainage area in the past 30 years. According to the Landsat satellite remote sensing data, the urbanization area expanded approximately three times from 1995 to 2010. The δ13C values (-21‰ to -23‰) of the organic matter (OM) in the sediments indicated that the OM was primarily sourced from aquatic, terrigenous and marsh C3 plants. Nitrogen was mainly derived from aquatic plants and terrigenous erosion before the 1980s. However, the total organic carbon (TOC) contents, total nitrogen (TN) contents and δ15N had been increasing since the 1980s, which suggested that the sources of nitrogen were soil erosion, fertilizer and sewage. In addition, the TOC and TN fluxes in the Dongshan Bay had significantly increased since the 1980s, which reflected the use of N fertilizer. However, the TOC and TN fluxes significantly decreased in the past decade because environmental awareness increased and environmental protection policies were implemented.

In this study, we described the distribution pattern of suspended particulate matter (SPM) and its influencing factors in the waters around the Minjiang River Estuary. Further, we investigated the flocculation process of SPM and its underlying mechanism in the study area. The objectives were achieved using water temperature, salinity, turbidity, fluorescence and particle size distribution of SPM data measured in August 2009. As influenced by dilution from the Minjiang River water, the water column structure was significantly stratified in the estuary, with an obvious thermocline and halocline. The turbidity was relatively low in the surface water (SSC 15 mg/l). Fluorescence was high (up to 10 μl/l) in the surface water, which was markedly lower and more uniform in the lower water layer. The total volume concentration and particle size of the SPM in the upper water layer were significantly higher than those of the lower water layer. The in-situ particle size frequency distribution of SPM markedly changed in the different water layers, whereas the dispersed particles were fine, with little difference in frequency distribution. The mean effective density of SPM was generally 3 in the surface and benthic water, and the values were slightly higher in the benthic water layer than in the surface water layer, with a significant increase in the middle water layer. The significant differences between the distribution trends of the total volume concentration and water turbidity were controlled by the size distribution of SPM. The concentration distribution of SPM was mainly influenced by source, re-suspension and thermocline, among other factors. Flocs widely occurred in the study area, and the flocculation mechanism of SPM varied in the different water layers. In the upper water layer, intense biological activity promoted the formation of stable macroflocs. In the benthic water layer, the biological activity was limited, the flocculation of sediment particles was mainly caused by physico-chemical attraction of inorganic particles, and the hydrodynamic conditions and high settling velocity were also unfavourable to the formation of macroflocs.

The trizinc complexes Zn3(OAc)4(Ln)2, 1a and 1b, which were coordinated with Schiff-base ligands via a simple and economical method, have been examined and found to be highly effective and efficient toward the copolymerization of CO2 and cyclohexene oxide (CHO). In this work, the kinetics for the copolymerization of CO2 and CHO using 1b as the catalyst was monitored via in situ ATR-FTIR spectroscopy. The reaction orders’ dependencies on catalyst concentration, initial CHO concentration and CO2 pressure, as well as activation energies (Ea) of polycarbonate and cyclic carbonate formation, were investigated in detail. The practical amount of active zinc sites in the copolymerization was calculated using the parameters obtained from 1H NMR and GPC measurements. The initiating reaction details were simulated using density functional theory, and the potential energy surfaces were obtained. Based on the results of all characterizations and kinetic investigations, a unique initiating reaction and copolymerizing mechanism were proposed when using Zn3(OAc)4(Ln)2 as the catalyst.

Real-time transdermal biosensing provides a direct route to quantify biomarkers or physiological signals of local tissues. Although microneedles (MNs) present a mini-invasive transdermal technique, integration of MNs with advanced nanostructures to enhance sensing functionalities has rarely been achieved. This is largely due to the fact that nanostructures present on MNs surface could be easily destructed due to friction during skin insertion. In this work, we reported a dissolvable polymer-coating technique to protect nanostructures-integrated MNs from mechanical destruction during MNs insertion. After penetration into the skin, the polymer could readily dissolve by interstitial fluids so that the superficial nanostructures on MNs could be re-exposed for sensing purpose. To demonstrate this technique, metallic and resin MNs decorated with vertical ZnO nanowires (vNWs) were employed as an example. Dissolvable poly(vinyl pyrrolidone) was spray-coated on the vNW-MNs surface as a protective layer, which effectively protected the superficial ZnO NWs when MNs penetrated the skin. Transdermal biosensing of H2O2 biomarker in skin tissue using the polymer-protecting MNs sensor was demonstrated both ex vivo and in vivo. The results indicated that polymer coating successfully preserved the sensing functionalities of the MNs sensor after inserting into the skin, whereas the sensitivity of the MN sensor without a coating protection was significantly compromised by 3-folds. This work provided unique opportunities of protecting functional nanomodulus on MNs surface for minimally invasive transdermal biosensing.

The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol is a green synthetic route owing to nontoxicity of starting materials and synthetic process. DMC is widely used as a nontoxic solvent, effective fuel additive, and synthetic intermediate in medicine, pharmaceutics, chemistry and other fields. The key challenge is to design efficient and stable catalysts, which mainly includes ionic liquids, alkali carbonates, transition metal oxides, heteropoly acids, supported catalysts. The problems of low yield and difficulties in experiments have not been fundamentally solved. Electro-assist synthesis that provides extra energy for CO2 activation is tried and membranes reactor that separates products in time to increase DMC yield is also studied. Dehydrant catalysts with in-situ hydration for water removal can significantly improve DMC yield and catalysts stability because chemical equilibrium shifts substantially and the catalysts deactivation by produced water poisoning is avoided. This direction will have a considerable breakthrough when appropriate combination of catalysts and dehydrant is obtained.

In this study, surface water samples were collected over several seasons from the Jiulong River mainstream (North and West Rivers) and estuary from 2013 to 2014. The concentration of dissolved inorganic carbon (DIC), stable carbon isotope composition (δ13CDIC), in-situ temperature, pH, and conductivity of the surface water were measured to study the source and fate of DIC in the Jiulong River. The results showed that the DIC concentrations decreased from upstream to downstream in the North River but increased in the West River, which was determined mainly by the lithology of the drainage basin. In spring, the river is fed by deep groundwater resources that are older and contain more DIC originating from carbonate weathering compared to surface water, resulting in the high concentration and δ13CDIC value of DIC. Whereas during the summer and autumn, the high runoff caused by frequent precipitation dilutes the DIC concentration of river water and the contribution of soil CO2 is more important, resulting in lower DIC concentration and δ13CDIC value. δ13CDIC values indicate that the DIC in the Jiulong River was derived mainly from the chemical weathering of bedrock, and CO2 outgassing was one of the main fates of the riverine DIC. Results of mixing ratio calculation in freshwater and seawater suggest that additional processes existed with the mixing process, which were identified as organic carbon degradation and respiration in summer and autumn and offshore water vertical mixing in winter and spring, but in general the spatial variation of DIC in the estuary was determined mainly by mixing of freshwater and seawater. This study complements our understanding of the sources and fates of DIC in small river systems on the continental margin of the East China Sea.

An economic and biocompatible Schiff base tri-zinc catalyst was used to synthesize homo/copolymers of l -lactide (LA) and e-caprolactone (CL) in bulk at first time. Both 1 H and 13 C NMR analyses show that LA is more active than CL, resulting in a poly(LA- grad -CL) copolymer with gradient sequence structure. A series of copolymers containing varying LA/CL ratios were readily synthesized. The chemical structure of poly(LA- grad -CL) was fully investigated using NMR and GPC technologies. TGA, DSC, DMA and nanoindentation instruments were employed to evaluate thermal and mechanical properties of these polymers. The results indicate that polymer composition and chain structure have a great impact on the crystallization behavior and crystallinity, as well as the thermal and mechanical properties of the copolymers. Therefore, the performance of the copolymer can be then tailored by simply adjusting the ratios of LA to CL.

A recent paper (Deng et al., 2017) reported detrital zircon geochronology from sandy sediments of the Lanyang River and the Zhuoshui River in the east and west Taiwan, respectively. They demonstrated that zircons from the Yangtze Block and the North China Block could be transported to the proto-Taiwan region by paleo-longshore currents. However, it is here suggested that, detrital zircons are unlikely to be transported over such long distances by paleo-longshore currents. Furthermore, the Min River in the Cathaysia Block might be a potential, and more accessible, primary provenance. The contribution of Min River to Taiwan sediments should be taken into account.

Novel semi-crystalline terpolymers with varying chain sequence structures derived from cyclohexene oxide (CHO), CO2 and e-caprolactone (CL) have been firstly synthesized and reported. The terpolymerization is catalyzed by Schiff base tri-zinc complexes via a one-step route. The tri-zinc complexes also exhibit a very high catalytic activity for the homopolymerization of e-caprolactone in the absence of CHO. A series of terpolymers with varying content of crystalline segments are produced by adjusting the feedstock ratio of CHO/e-CL. The reactivity of different monomers was investigated by experimental methodology. The results indicate that e-CL is much more active than CHO in this terpolymerization system. Therefore, the incorporation of e-CL can dramatically improve the TONs of terpolymer containing e-CL moieties. Moreover, the thermal properties of the resulting terpolymers were also studied by DSC and TGA. Finally, the polymerization mechanism of this ternary system is extensively discussed based on experimental phenomena. To the best of our knowledge, this is the first report on novel catalysts capable of synthesizing polycarbonates, polyesters and poly (carbonate-ester) via a one-step polymerization.

To understand the source-to-sink of pollutants in the Kelantan River estuary and the adjacent shelf area in Malaysia, a total of 42 surface sediment samples were collected in the Kelantan River-estuary-shelf system to analyze for grain size, total organic carbon (TOC) content, Al and heavy metals (Cr, Ni, Cu, Zn, Cd and Pb). The surficial sediments were mainly composed of clayey silt and the TOC content in sediments decreased from the river to the shelf. The surficial sediments experienced Pb pollution; Cr only showed a certain level of pollution in the coastal area of the estuary but not in other areas, and Ni, Cu, Zn, and Cd showed no pollution. The heavy metals mainly originated from natural weathering and erosion of rocks and soils in the catchment and enriched near the river mouth. Total organic carbon can promote the enrichment of heavy metals in sediments.

Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were1.5, indicating minor pollution. The results indicate that the sediments of the MJK16 core have Cu and Pb concentrations increasing since 1980, associated with the increase of magnetic mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China.

The thermal degradation behaviors and mechanisms of CO2-based poly(cyclohexene carbonate caprolactone)s (PCHCCLs) were deeply studied taking advantage of thermogravimetric analysis/Fourier transform infrared spectrometry (TG/FTIR) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) techniques. The experimental results indicate that the decomposition temperatures of PCHCCLs increase with the increasing contents of polycaprolactone (PCL) segments. Backbiting reaction was found to be the dominant degradation pathway for PCHCCLs, and a complicated random rupture process was also observed at higher pyrolysis temperature.

Bamboo charcoal (BC) has a natural hierarchical porous three-dimensional network structure and good electrical conductivity. Herein, MoS2 nanoflakes supported by modified bamboo charcoal (MBC) have been prepared via a facile hydrothermal method using ammonium molybdate. SEM observations show that appropriate MoS2 nanoflakes are uniformly dispersed on the porous MBC. In addition, the hybrids exhibit good lithium storage property as anode materials for lithium ion batteries. The optimal MoS2/MBC (MS-2) composite delivers a high initial capacity of 1867 mAh g−1 at the current density of 200 mA g−1, along with a stable reversible capacity of 672 mAh g−1 during 200 cycles and the impressive high-rate capacity of 581 mAh g−1 even at a higher current density of 1600 mA g−1. The superior electrochemical performances of MoS2/MBC composites can be attributed to the synergistic effects between MoS2 nanosheets and the hierarchical porous structure of MBC, which buffers the volume change of materials, enhances the conductivity of composites and transmission of electrolyte.

In situ U–Pb dating and Hf isotopic of detrital zircons from beach sediments of Yalong Bay were analyzed to trace sedimentary provenance and reveal the crustal evolution of Hainan Island in South China. The grain size distribution of the sediments displays a clear single-peak feature, indicating the sediments were formed under the same condition of hydrodynamic force. The detrital zircons had Th/U ratios of greater than 0.1, and REE pattern displayed a positive Ce anomaly and a negative Eu anomaly, indicating that these zircons are predominantly of magmatic origin. The U–Pb spectrum of detrital zircons mainly peaked at the Yanshanian (96–185 Ma), Hercynian–Indosinian (222–345 Ma) and Caledonian (421–477 Ma). A portion of the detrital zircons were of Neoproterozoic origin (728–1,003 Ma), which revealed that the basement in the eastern region of Hainan Island was mainly of Neoproterozoic, with rare Archean materials. The positive eHf(t) values (0 to +10.1) of the Neoproterozoic detrital zircons indicated that the juvenile crust grew in the southeastern Hainan Island mainly during the Neoproterozoic period. The Neoproterozoic orogeny in the southeastern part of the island (0.7–1.0 Ga) occurred later than in the northwestern region of the island (1.0–1.4 Ga). Importantly, the Grenvillian orogeny in the southeastern area of Hainan Island shared the same timing with that of the western Cathaysia Block; i.e., both areas concurrently underwent this orogenic event, thereby forming a part of the Rodinia supercontinent. Afterwards, the crust experienced remelting and reworking during the Caledonian Hercynian–Indosinianand Yanshanian accompanied by the growth of a small amount of juvenile crust.

Sediment transport in estuarine systems has been of increasing interest for scientists during the past few decades. However, the mechanisms for sediment redistribution remain unclear. We characterized in detail sediment transport in the Xiaoqing River estuary using the mathematical Weibull function to partitiongrain-size components of surface sediments in the southwestern Laizhou Bay, Northeast China. Four partitioned components: finer than 4, 4.6–12.5, 23.4–63.3, and 67.1–132.6 μm were interpreted in terms of hydrodynamic conditions. During sediment transport, silt grains were suspended and moved seaward from three depositional centers, whereas fine-grained sands moved generally landward. Overall, sediments are transported clockwise in a generally NNE direction near shore and then turn eastward offshore. The mathematical partitioning method showed a great potential for future estuarine environmental studies.

It has been suggested that the standardized growth curve (SGC) method can be used to accurately determinate equivalent dose (De) and reduce measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we evaluated quartz OSL SGCs of marine and coastal sediments of different grain sizes and different cores in the south Bohai Sea in China, and tested their applicability to the determination of De values. Our results suggested as follows: (1) The SGC method is applicable to both multiple- and single-aliquot regenerative-dose (MAR and SAR) protocols of OSL dating and efficiently provides reliable estimates of De. (2) Finesand quartz of different palaeodoses showed highly similar dose-response curves and an SGC was developed, but old samples using the SGC method have large uncertainties. (3) For coarse-silt quartz, two different types of dose-response curves were recorded: low-dose (≤60Gy) and high-dose (≥100Gy). The growth curves of low-dose quartz were similar to each other, facilitating the use of SGC in De estimations, but errors tended to be larger than those obtained in the SAR method. For high-dose (100–300Gy) quartz, the SGC was also found to be reliable, but there was large uncertainty in De (>300Gy) estimation. We suggest that SGC could be employed for the dating of marine and coastal sediments dating using either MAR or SAR OSL protocol and either fine-silt, coarse-silt or fine-sand quartz.

Eighty-six surface sediments collected from the northwestern continental shelf of the South China Sea (SCS) were analyzed for grain size distribution, calcium carbonate, organic carbon, and major and trace element compositions to investigate sediment provenance and factors controlling their geochemical composition. Sediments from the eastern continental shelf of Hainan Island have higher sand and lower clay content, while the samples from the nearshore Hainan Island have higher contents of gravel and clay. Calcium carbonate contents in samples show a positive correlation with water depth in northwestern shelf of SCS, suggesting that it is related to biological factors. However, the nearshore sediments have higher contents of organic carbon compared to those of the outer shelf, possibly suggesting that the terrigenous organic matter usually deposited in nearshore environments such as bays and estuaries. Compared with the upper continental crust, the samples have relatively lower contents of SiO2 and Al2O3, higher than those of the Pearl and Red river sediments. The low contents of K2O and Na2O in sediments from the northwestern continental shelf are consistent with intense chemical weathering in the river basin due to the seasonally hot and humid climate regime. The sediments mainly consist of three components, including the gravel fraction composed of calcareous debris, the sand fraction composed of quartz, and the silt and clay fractions mainly composed of clay minerals. The content of each component depends on grain size, sediment source, biogenesis, and hydrodynamic conditions, which finally controls the chemical composition of the sediments. The distributions of Co/Al2O3, Cr/Al2O3, and Zr/Sc ratios for sediments in the northwestern continental shelf suggest that source rocks are mainly composed of felsic rocks rather than mafic rocks. There is a distinct difference in sediment source between eastern and western shelf sediments; the eastern shelf sediments are characterized by high Zr/Sc ratios mainly derived from the Pearl River, while the western shelf sediments have relatively low values of Zr/Sc indicating a main contribution possibly sourced from the Red River Basin. Terrigenous materials from Hainan Island usually influence the geochemistry of sediments deposited in the nearshore area.

A spatial-temporal model with Model Maker tool is designed to retrieve Land Surface Temperature (LST) and to describe the changes of urban heat island, as well as urban development. Spectral Radiance, Brightness Temperature, NDVI, and Emissivity are first calculated from TM and ETM+, which are then used to compute LST by using Qin et al.’s mono-window algorithm. The LST is classified based on normalized statistical method, and the normalized heat images are computed between different times. Therefore, the urban heat changes can be shown in the map clearly and directly through an urban heat conversion matrix. Such a model has been applied in this study to obtain the urban heat conversion matrix of South China from 1990 to 2000. The results indicate that the LST increased areas mainly locate along the major roads in the eastern bank of the Pearl River, which is a result of speedy urban expansion and need to be noticed in the future.

Biodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene-co-vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen-bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases. POLYM. ENG. SCI., 47:174–180, 2007. © 2007 Society of Plastics Engineers

Typhoons have a significant effect on the marine depositional environment and depositional process. In this paper, we used the high-resolution Chirp sonar sub-bottom profiler and radioisotope detection techniques to examine the storm-deposited layer formed in the seawater near the path of Typhoon Saola along the coast of Fujian, China. The thickness of the typhoon-deposited layer acquired using these two methods was 10–25 cm. The thickness, sediment grain size and δ13C values of the deposited sedimentary layer indicated that it was mainly matter from the re-suspension and redistribution of seafloor sediments. The particle sizes of the sediments in the storm-deposited layer became coarser, indicating that the fine-grade compositions spread over a wider range out of the coastal zone.

A series of poly(arylene ether)s containing triphenylmethane moiety were synthesized by the nucleophilic displacement of aromatic dihalides with bisphenols in an aprotic solvent in the presence of excess potassium carbonate. High molecular weight and fibrous polymers in white color can be readily afforded in short reaction time. The structures of the synthesized monomers and polymers were investigated by 1H NMR and MS techniques. The sulfonation position of the synthesized polymer can be easily controlled and the water-up-take can be conveniently tailored by changing the amount of sulfonation agent. This sulfonated polymer 4b is soluble in polar organic solvents, such as NMP, DMAc, DMSO, DMF, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The sulfonated polymers can be potentially used as the proton-exchange membranes for fuel-cells.

A series of salicylaldiminato-zinc and -tri-zinc complexes containing various Schiff base ligands were prepared using quick methods and then well identified by full characterization. All zinc complexes were examined as catalysts for the copolymerization of CO2 and cyclohexene oxide. Many factors such as electron-donating or -withdrawing substituents on the benzene rings of the ligands, as well as chloride anions or acetate groups bound to the zinc centers, are found to greatly influence on the insertion of CO2 and ring-opening of epoxides. Tri-metallic complexes 2a and 2b exhibited excellent catalytic activities, and thus the copolymerization conditions such as temperature, pressure and reaction time were optimized. The molecular weights of the resulting copolymers determined by gel permeation chromatography display a bimodal distribution with relatively wide polydispersities. The results of the investigation indicate that the catalytic activities of zinc complexes are highly dependent on the electronic density and steric environment around the Zn metal centers.

In situ detrital zircons U-Pb and Hf isotope analyses from the Min and Jiulong River of Southeast China were carried out to identify sediment provenance and crustal evolution of the northeast Cathaysia Block. Detrital zircons from both rivers displayed similar spectrum peaks at 236, 155, and 110 Ma, but samples from the Min River displayed a distinct Caledonian peak (ca. 460 Ma) and contained more Precambrian particles (ca. 1.8 Ga), which likely stemmed from the upstream area of the Wuyishan terrain. Interestingly, because Taiwan Island cannot supply Caledonian and Paleoproterozoic detrital materials and because the Ou and Jiulong River also lack components from these two populations, it is highly likely that the sediment in the western Taiwan coast partially originates from the Min River. The sediments from the Min River in Fujian are also considered the most likely source of the beach sands of western Taiwan (Chen et al. 2006). However, we stress that the ~1.8 Ga age source in the western Taiwan sediments was found and recognized. Combining U-Pb dating and Hf-isotope suggests that the northeast Cathaysia Block contains some Neoarchean detrital zircons, which derived from the incorporation of juvenile mantle materials and re-melting of ancient crustal substances. The wide ranges of εHf(t) value in the Paleoproterozoic and Neoproterozoic demonstrate the re-melting of ancient crustal materials with minor juvenile mantle materials. Phanerozoic zircons stemmed from re-melting and recycling of Proterozoic crustal materials with or without the invasion of juvenile mantle-derived magmas.