Enabling Visible-Light-Charged Near-Infrared Persistent Luminescence in Organics by Intermolecular Charge Transfer.

Visible light is a universal and user-friendly excitation source; however, its use to generate persistent luminescence (PersL) in materials remains a huge challenge. Herein, the concept of intermolecular charge transfer (xCT) is applied in typical host-guest molecular systems, which allows for a much lower energy requirement for charge separation, thus enabling efficient charging of near-infrared (NIR) PersL in organics by visible light (425-700 nm). Importantly, NIR PersL in organics occurs via the trapping of electrons from charge-transfer aggregates (CTAs) into constructed trap states with trap depths of 0.63-1.17 eV, followed by the detrapping of these electrons by thermal stimulation, resulting in a unique light-storage effect and long-lasting emission up to 4.6 h at room temperature. The xCT absorption range is modulated by changing the electron-donating ability of a series of acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile-based CTAs, and the organic PersL is tuned from 681 to 722 nm. This study on xCT interaction-induced NIR PersL in organic materials provides a major step forward in understanding the underlying luminescence mechanism of organic semiconductors and these findings are expected to promote their applications in optoelectronics, energy storage, and medical diagnosis.

Evidence for coupled iron and nitrate reduction in the surface waters of Jiaozhou Bay.

Iron and nitrate (NO3-) are dominant physiologically required nutrients for phytoplankton growth, and iron may also play a key role in the marine nitrogen cycle. In this study, we investigated the temporal and spatial distributions of dissolved iron (DFe) and Fe(II) in the surface waters of Jiaozhou Bay (JZB) from April 2 to July 26, 2017. High concentrations of DFe and Fe(II) predominantly occurred in nearshore and estuarine stations and concentrations were generally higher in April and May. The highest DFe concentration was observed along the coast of Hongdao (51.55 nmol/L) in May, while the lowest concentration was observed in the western coastal region (2.88 nmol/L) in April. The highest and lowest Fe(II) concentrations were observed in the Licun estuary (22.42 nmol/L) and outer bay (0.50 nmol/L) in May, respectively. We calculated the proportions of nitrate, nitrite, and ammonium in dissolved inorganic nitrogen (DIN) as well as the ratio of Fe(II) to DFe in all four months. The mean Fe(II)/DFe ratio was 0.48 in April, 0.43 in May, 0.69 in June, and 0.32 in July. The mean ratio of NO3- to DIN was 0.78 in April, 0.54 in May, 0.20 in June, and 0.62 in July. NO3-/DIN continuously decreased in the first three months, while Fe(II)/DFe remained high, which suggests that the reduction of iron and nitrate occurred simultaneously in the surface waters of JZB.

Seasonal and spatial variabilities of dissolved iron in southern Yellow Sea.

The southern Yellow Sea (SYS) is considered to be of the most prolific fishing grounds in the China Sea. In this study, the seasonal and spatial distributions of total dissolved iron (DFe) are investigated across four seasons in the SYS, from July 2013 to January 2016. This investigation showed that the DFe values of all samples exhibited seasonal variations: summer (1.7-15.8 nM), autumn (0.9-38.5 nM), winter (3.0-69.8 nM), and spring (3.0-100.2 nM). The DFe values in both surface and bottom waters also exhibited distinct temporal changes. The influence of water masses on the distribution of DFe as well as other factors, such as major nutrient concentrations of total dissolved nitrogen, total dissolved phosphate, and hydrologic factors, was investigated in this study. Based on the investigation of DFe and major nutrients in the SYS, the Yellow Sea Cold Water Mass was identified as the most conservable water mass in the study area. The results of this study further indicate that in winter, DFe0.4 µm (using a 0.4 µm filter) is considerably higher than DFe0.2 µm (using a 0.2 µm filter) in the surface water of the SYS coastal area. Therefore, the dissolution of colloidal Fe in this area had a significant effect on DFe.

Influence of humic substances on iron distribution in the East China Sea.

The influence of humic substances (specifically humic and fulvic acids, referred to as HS-HA and HS-FA) as well as other factors, such as major nutrient concentrations of total dissolved nitrogen (TDN), total dissolved phosphate (TDP) and hydrologic factors, on the distribution of total dissolved iron (DFe) and the chemical speciation of DFe was studied in the East China Sea (ECS) during a summer cruise in 2013. As the wide rage fraction of nature organic matter, the HS-HA, HS-FA in ESC contains most part of the organic ligand (Lt) of DFe. The concentrations of HS-HA, DFe and Lt in coastal water masses were higher than those in the water masses affected by the Kuroshio Current. The highest concentrations of HS-HA and DFe were observed in surface water at stations MT1 and MC4, with the value of 336.5 µg SRHA/L and 20.3 nmol/L, respectively, whereas, the lowest concentrations of HS-HA and DFe were observed in surface waters with the value of 149.6 µg SRHA/L and 0.4 nmol/L, respectively. HS-HA concentrations were more conservative than that of DFe. The DFe which were combined by unit weight HS-HA (mg-1, IB) in the surface and bottom waters quickly decreased with increasing salinities from the Yangtze River estuary to the southeast of the ECS. Average IB values in bottom waters were higher than those in surface waters. This study indicated that Yangtze River dilution water and cold water from the Yellow Sea were the main source of HS-HA and DFe in ECS.

Capacity of humic substances to complex with iron at different salinities in the Yangtze River estuary and East China Sea.

The iron binding capacities (IBC) of fulvic acid (FA) and humic acid (HA) were determined in the salinity range from 5 to 40. The results indicated that IBC decreased while salinity increased. In addition, dissolved iron (dFe), FA and HA were also determined along the Yangtze River estuary's increasing salinity gradient from 0.14 to 33. The loss rates of dFe, FA and HA in the Yangtze River estuary were up to 96%, 74%, and 67%, respectively. The decreases in dFe, FA and HA, as well as the change in IBC of humic substances (HS) along the salinity gradient in the Yangtze River estuary were all well described by a first-order exponential attenuation model: y(dFe/FA/HA, S) = a0 × exp(kS) + y0. These results indicate that flocculation of FA and HA along the salinity gradient resulted in removal of dFe. Furthermore, the exponential attenuation model described in this paper can be applied in the major estuaries of the world where most of the removal of dFe and HS occurs where freshwater and seawater mix.

Characteristics of trace metals and phosphorus in seawaters offshore the Yangtze River.

This study presents the spatial distribution of total dissolved Cu, Zn, Co, and V during an autumn survey in the East China Sea (ECS). Dissolved Fe and its organic complexation were also investigated. The present study aimed to evaluate the relationship between Cu, Zn, Co, V, D-Fe and its organic ligands and total dissolved phosphate (TDP) in the coastal waters of the ECS. A correlation analysis shows that Cu, Zn and D-Fe were nutrient-like metals, whereas Co and V were non-nutrient-like metals. A multivariate statistical analysis showed that TDP was associated with D-Fe, Cu, Zn and Co, but was not associated with V. Furthermore, TDP was observed to be positively related with D-Fe, while negatively with Fe', which indicated that the limitation of TDP decreased the uptake of Fe'. This paper improves our understanding of the association among trace metals, TDP and phytoplankton biomass in the ECS.

The distribution of dissolved lead in the coastal waters of the East China Sea.

The distribution of dissolved lead in the coastal waters of the East China Sea was investigated seasonally. The average concentrations in surface waters during the spring and autumn were 0.52 nM and 0.27 nM, respectively. In the spring, the concentration of dissolved Pb in the surface waters and bottom waters ranged from 0.13 to 1.86 nM and from 0.15 to 0.94 nM, respectively. For both the surface water and the bottom water, the highest values were observed at the Yangtze River Estuary. Seasonal variability of D-Pb between spring and autumn in the ECS was observed. These results suggested that riverine inputs and atmospheric inputs may be the main sources of lead in this area, while adsorption and co-precipitation on suspended particles at the river estuary and biological process may be the major sinks.

Reactive iron and its buffering capacity towards dissolved sulfide in sediments of Jiaozhou Bay, China.

Reactive iron (Fe) oxides in marine sediments play a critical role in removal of free sulfide. In this study, 0.5 and 6 N HCl-extractable Fe, acid volatile sulfide (AVS), and pyrite were examined in sediments at three sites of eutrophic Jiaozhou Bay to investigate the interactions of sulfur and Fe and possible influences of eutrophication on free sulfide removal. The results indicate that formation and accumulation of AVS and pyrite are limited by low availability of labile organic matter, despite eutrophication of the bay water. Quick buffering of free sulfide proceeded mainly via consumption of 0.5 N HCl-extractable Fe (labile Fe), however, the consumption did not result in a depletion of the Fe pool. High residual buffering capacity enables a quick removal of free sulfide in porewater, and thereby it is difficult for sulfide to accumulate and to cause detrimental effects on benthic organisms at the present steady state. Significant effects of eutrophication on Fe and sulfur geochemistry is restricted only to the estuarine sediments which were subject to direct wastewater discharges, whereas no such effects were observed in other sediments of the bay.

Metal complexation by humic substances in seawater.

We determined the complex stability of copper, zinc, cobalt and aluminum with humic acid (HA) and fulvic acid (FA) in pH 8 seawater. The method is based on metal competition against iron, for which the complex stability with humic substances (HS) in seawater had been calibrated previously against EDTA. The conditional stability constants, log K'(Mn+HS) values, were found to decrease in the order of Cu > Zn > Co and Fe > Al. The complex stability of the HA species was greater than the FA species, but all determined complex stabilities are sufficiently high for significant complexation of the examined metals by HS in seawater. Data modeling shows a good data fit over the entire titrations for Cu and Co and for low levels of Zn. A second site on the HS appears to bind higher levels of Zn. The Al data suggest that Fe is exchanged for Al at a ratio different from 1:1. The data suggests that HS may be an important ligand for these metals in seawater.

[Effects of Cd (II) on the growth of 8 species of marine microalgae].

Effects of Cd (II) on the growth of 8 species of marine microalgae were studied in batch culture experiment. The experimental results show that higher doses of Cd (II) inhibite the growth of Heterosigma akashiwo Hada. Chaetoceros curvisetus. Skeletonema costatum (Greville) Cleve, Pheodactylum tricornutum Bohlin, Prorocentrum micans. Gymnodinium sp., Platymonas helgolanidica, Platymonas subcordiforus. But, lower doses of Cd (II) (50 microg/L and 100 microg/L) promote the growth of Skeletonema costatum (Greville) Cleve and Platymonas helgolanidica. A growth model, with consideration of effect of Cd (II) on the growth of marine microalgae, was developed by incorporating Logistic growth model with Lorentz equation and GaussAmp equation. Lorentz equation can describe the effect of Cd (II) on the growth rate constant while GaussAmp equation can describe the effect of Cd (II) on the final biomass of microalgae. It was demonstrated that the growth model showed in accordance with the experimental data.

Effects of anesthesia-induced modest hypothermia on cellular radiation sensitivity.

To assess the mechanisms of modest hypothermia (MH) and its effects on cellular radiation response, a model of anesthesia-induced modest hypothermia (AIMH) in the adult mice and a model of pure MH in the newborn mice were established. The survival rate of lethally irradiated mice was increased to 72% through AIMH before irradiation. Both apoptosis and necrosis of human fetal bone marrow CD34(+) hematopoietic stem cells cultured under MH were significantly decreased as detected by MTT and flow cytometry, with three-color labeled by PE-CD(34) (+)/ FITC-AnnexinV /7AAD. The survival and proliferation of mouse bone marrow MNC treated with MH after irradiation were also increased. The MH exerted similar protective effects on the leukemia cell lines A20, HL60, K562 to the normal bone marrow cells, but it enhanced the radiation sensitivity of leukemia cell line FBL3 and mouse melanoma B16F10. No effects have been found on the radiation sensitivity of those cells treated with MH before irradiation. The results also showed that MH mediated the effects on radiation sensitivity, in addition to increasing the oxygen tension. These results show different effects of MH on different cells: (i) AIMH exerts a protective effect on the normal hematopoietic stem cells, some leukemia cell lines A20, HL60, K562, and some neoplasma 3LL, LOVO. And MH exhibits a synthetic effect with anesthetic. (ii) MH enhances the radiation sensitivity of another leukemia and neoplasma cell lines FBL3, B16F10 and CT26. Therefore, AIMH has a potential to enhance the effects of radiation-therapy and decrease side effects on some tumors.

Anthraquinones from hairy root cultures of Cassia obtusifolia.

Hairy root cultures of Cassia obtusifolia clones transformed with Agrobacterium rhizogenes strain 9402 were established to investigate the anthraquinone production. Seven anthraquinones, together with betulinic acid, stigmasterol and sitosterol were isolated from the hairy roots. Their chemical structures were elucidated on the basis of chromatographic and spectral data. The effects of culture conditions and rare earth element Eu(3+) on the production of six free anthraquinones have also been investigated. It was found that changes of the elements in the culture medium and addition of rare earth element Eu(3+) can greatly influence the contents of free anthraquinones in the hairy roots.