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Organic ultralong room temperature phosphorescence (OURTP) materials with photophysical properties sensitive to external stimulus are highly attractive for advanced applications. However, most OURTP molecules are in crystal and OURTP materials with good practicability and stimulus-responsive character are hard to be achieved. Here, we report, for the first time, the highly efficient, ultralong-lived and deep-blue OURTP materials by simply doping boron phosphor into cyanuric acid host. Thus constructed host-guest OURTP composites with abundant and tunable H-bond network are highly stable in air with ultralong lifetime of 5.08 s at room temperature, and more interestingly, are sensitive to water, which can strength the H-bond network to significantly enhance OURTP quantum yield from 16.1% to 37.6%. With the extraordinary water-responsive OURTP, anti-counterfeiting paper was facilely prepared for water-jet printing and the jet-printed high-resolution OURTP patterns can be easily erased by solvent fuming for another printing/erasing cycle with high reversibility.

Qi-Xing Tian,1,* Zhi-Hui Zhang,1,* Qing-Lin Ye,1 Shen Xu,1 Qian Hong,1 Wei-Yang Xing,1 Lei Chen,1 De-Xin Yu,1 De-Xiang Xu,2,3 Dong-Dong Xie1 1Department of Urology, Second Affiliated Hospital, Anhui Medical University, Hefei, 230601, People’s Republic of China; 2Department of Toxicology, Anhui Medical University, Hefei, 230032, People’s Republic of China; 3Laboratory of Environmental Toxicology, Anhui Medical University, Hefei, 230032, People’s Republic of China*These authors contributed equally to this workCorrespondence: De-Xiang XuDepartment of Toxicology, Anhui Medical University, Hefei, 230032, People’s Republic of ChinaTel +86 138 6674 1832Email xudex@126.comDong-Dong XieDepartment of Urology, Second Affiliated Hospital, Anhui Medical University, Hefei, 230601, People’s Republic of ChinaTel +86 138 6670 0010Email xiedd_urology@163.comPurpose: Gram-negative bacteria are usually found in prostate cancer (PCa) tissues. This study aims to investigate the role of lipopolysaccharide (LPS), a glycolipid compound found in the outer membrane of gram-negative bacteria, on the migration and invasion of PCa cells, and to evaluate the protective effect of melatonin.Materials and Methods: DU145, PC-3 and LNCaP cells were incubated with LPS in the presence or absence of melatonin. Wound healing and Transwell assays were used to analyze migration and invasion of PCa cells. RT-PCR and Western blotting were used to assess the mRNA and protein levels, respectively. Co-IP was used to analyze β-catenin ubiquitination.Results: Our results showed that LPS promoted migration and invasion of PCa cells. In addition, LPS stimulated inflammatory reaction and induced epithelial–mesenchymal transition (EMT) in PCa cells by activating several TLR4 downstream pathways. Specifically, LPS promoted NF-κB/IL-6/STAT3 signal transduction. In addition, LPS upregulated phosphorylation levels of cytoplasmic AKTSer473 and GSK-3βSer9. Moreover, LPS induced phosphorylation of GSK-3βSer9 in the “disruption complex”, and then inhibited phosphorylation and ubiquitination of cytoplasmic β-catenin, leading to β-catenin nuclear translocation. Interestingly, melatonin inhibited invasion and migration not only in LPS-stimulated but also in LPS-unstimulated PCa cells. Melatonin suppressed PCa cells migration and invasion by blocking EMT mediated by IL-6/STAT3, AKT/GSK-3β and β-catenin pathways.Conclusion: This study provides evidence that melatonin inhibits migration and invasion through blocking multiple TLR4 downstream EMT-associated pathways both in LPS-stimulated and -unstimulated PCa cells. Our results provide new insights into the role of bacterial infection in PCa metastasis and a potential therapeutic agent.Keywords: β-catenin, EMT, lipopolysaccharide, melatonin, prostate cancer

Phthalates are one of ubiquitous contaminants in the indoor environment. In this study, we analyzed concentrations and profiles of 9 phthalates in dust samples collected from houses and university dormitories in Nanjing, China. The total concentrations of phthalates in house and dormitory dust ranged from 111.4 to 3599.1 µg/g and 86.1 to 1262.3 µg/g, respectively. Phthalates in house was significantly higher than that in dormitory dust (p

Concentrations and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and polycyclic aromatic hydrocarbons (PAHs) in a rural atmosphere near industrial zones in Jiangsu, China were determined and the associated risks were assessed. The concentrations of ΣPCDD/Fs, ΣPCBs, and ΣPAHs ranged from 11.9–57.7 pg·m−3, 0.58–2.71 pg m−3, and 11–18 ng m−3, respectively. Principal component analysis suggested that the contamination of air with PCDD/Fs and PCBs mainly originated from industrial activities and combustion processes. In contrast, the major source of PAHs was the combustion of petroleum, coal, and biomass. These data were used to estimate the exposure of the population living nearby to these persistent organic pollutants and to evaluate the non-carcinogenic and carcinogenic risks associated with their inhalation. Our study are likely to be helpful for developing and implementing regulation strategies for PCDD/Fs, dl-PCBs, and PAHs in the atmosphere around industrial and surrounding residential areas.

BackgroundVacuolar H+-ATPase (V-ATPase) is a highly conserved protein complex which hydrolyzes ATP and pumps protons to acidify vacuolar vesicles. Beyond its role in pH maintenance, the involvement of V-ATPase in endocytosis is well documented in mammals and plants but is less clear inTrypanosoma brucei.MethodsIn this study, the subcellular localization of V-ATPase subunit B (TbVAB) ofT. bruceiwas assessedvia in situN-terminal YFP-tagging and immunofluorescence assays. Transgenic bloodstream forms (BSF) ofT. bruceiwere generated which comprised either a V-ATPase subunit B (TbVAB) conditional knockout or a V-ATPase subunit A (TbVAA) knockdown. Acridine orange and BCECF-AM were employed to assess the roles of V-ATPase in the pH regulation of BSFT. brucei. The endocytic activities of three markers were also characterized by flow cytometry analyses. Furthermore, trypanosomes were counted from trypanolysis treatment groups (either containing 1% or 5% NHS) and endocytosed trypanosome lytic factor (TLF) was also analyzed by an immunoblotting assay.ResultsTbVAB was found to localize to acidocalcisomes, lysosomes and probably also to endosomes of BSF ofT. bruceiand was demonstrated to be essential for cell growth.TbVABdepletion neutralized acidic organelles at 24 hours post-tetracycline depletion (hpd), meanwhile the steady state intracellular pH increased from 7.016 ± 0.013 to 7.422 ± 0.058. Trypanosomes withTbVABdepletion at 24 hpd were found to take up more transferrin (2.068 ± 0.277 fold) but less tomato lectin (49.31 ± 22.57%) by endocytosis, while no significant change was detected in dextran uptake. Similar endocytic dysregulated phenotypes were also observed inTbVAAknockdown cells. In addition,TbVABdepleted trypanosomes showed a low uptake of TLF and exhibited less sensitive to lysis in both 1% and 5% NHS treatments.ConclusionsTbVAB is a key component of V-ATPase and was found to play a key function in endocytosis as well as exhibiting different effects in a receptor/cargo dependent manner in BSF ofT. brucei. Besides vacuolar alkalinization, the dysregulation of endocytosis inTbVABdepletedT. bruceiis considered to contribute to the reduced sensitivity to lysis by normal human serum.

Low vitamin D status is associated with progression in patients with renal cell carcinoma (RCC). The present study found that vimentin, a mesenchymal marker, was accordingly upregulated, and E‐cadherin, an epithelial marker, was downregulated in RCC patients with low vitamin D status. Thus, we investigated the effects of calcitriol or vitamin D3, an active form of vitamin D, on epithelial‐mesenchymal transition (EMT) in RCC cells. RCC cells were treated by two models. In model 1, three RCC cell lines, ACHN, 786‐O and CAKI‐2, were incubated with either LPS (2.0 μg/mL) or transforming growth factor (TGF)‐β1 (10 ng/mL) in the presence or absence of calcitriol (200 nmol/L). In model 2, two RCC cell lines, ACHN and CAKI‐2, were incubated with calcitriol (200 nmol/L) only. Calcitriol inhibited migration and invasion not only in TGF‐β1‐stimulated but also in TGF‐β1‐unstimulated RCC cells. Moreover, calcitriol suppressed E‐cadherin downregulation and vimentin upregulation not only in TGF‐β1‐stimulated but also in TGF‐β1‐unstimulated ACHN and CAKI‐2 cells. Calcitriol attenuated LPS‐induced upregulation of MMP‐2, MMP‐7, MMP‐9, MMP‐26 and urokinase‐type plasminogen activator (u‐PA) in ACHN cells. In addition, calcitriol blocked TGF‐β1‐induced nuclear translocation of ZEB1, Snail and Twist1 in ACHN and CAKI‐2 cells. Mechanistically, calcitriol suppressed EMT through different signaling pathways: (i) calcitriol suppressed Smad2/3 phosphorylation by reinforcing physical interaction between vitamin D receptor (VDR) and Smad3 in TGF‐β1‐stimulated RCC cells; (ii) calcitriol inhibited signal transducer and activator of transcription (STAT)3 activation in LPS‐stimulated RCC cells; (iii) calcitriol inhibited β‐catenin/TCF‐4 activation by promoting integration of VDR with β‐catenin in TGF‐β1‐unstimulated RCC cells. Taken together, calcitriol inhibits migration and invasion of RCC cells partially by suppressing Smad2/3‐, STAT3‐ and β‐catenin‐mediated EMT., Calcitriol suppressed EMT through two different signaling pathways: (i) calcitriol suppressed Smad2/3 phosphorylation by reinforcing physical interaction between vitamin D receptor (VDR) and Smad3 in TGF‐β1‐stimulated RCC cells; (ii) calcitriol inhibited β‐catenin/TCF‐4 activation by promoting integration of VDR with β‐catenin in TGF‐β1‐unstimulated RCC cells. Taken together, calcitriol inhibits migration and invasion of RCC cells by suppressing Smad2/3‐ and β‐catenin‐mediated EMT.

Exciting progress has been made recently regarding organic field-effect transistors (OFETs) owing to significant efforts devoted to the material design of semiconducting conjugated small molecules and polymers. However, the development of ambipolar or n-type OFETs lags behind that of p-type devices. Here, we propose a new strategy for the design of ambipolar polymers based on acceptors (A) of diazines (pyridazine or pyrazine) in a “moderate A-weak A (mA-wA)” architecture by integrating intrachain noncovalent interactions to rationally engineer the electronic structure, molecular planarity and backbone curvature of the conjugated copolymers. Thus designed mA-wA polymers with intrachain N⋯S interactions exhibit both high-lying HOMO and low-lying LUMO energy levels for ambipolar charge transport and good planarity with a linear backbone for high and balanced hole and electron mobilities up to 0.39 and 0.30 cm2 V−1 s−1, respectively. Furthermore, the flexible OFETs fabricated on polyethylene terephthalate substrates show high mobilities of 0.26 and 0.32 cm2 V−1 s−1 for holes and electrons, respectively. This design strategy with the newly discovered diazine acceptors to invoke both mA-wA and NCI effects in conjugated polymers for backbone engineering may be applicable to other systems, representing an advanced concept for the construction of high-performance ambipolar polymers.

Molecular conformation plays an important role in tuning the packing modes of organic optoelectronic materials to achieve enhanced and/or balanced charge transport. Here, we introduce the noncovalent intramolecular interactions to the host materials of phosphorescent organic light-emitting diodes (PhOLEDs). Different numbers and/or positions of intramolecular CH···N noncovalent interactions were constructed by using different N-heterocycles of pyridine, pyrimidine, and pyrazine as acceptor units and carbazole as the donor unit in a donor-acceptor-donor (D-A-D) motif. Thus, designed D-A-D molecules were synthesized facilely through a one-step Ullmann reaction in high yields, showing varied intramolecular interactions to regulate the molecular conformation significantly. Impressively, owing to the quasi-parallel molecular conformation, which is beneficial for forming facile transporting channels of both holes and electrons, the newly designed host material of 9,9′-(pyridine-2,5-diyl)bis(9H-carbazole) exhibits good device performance of blue PhOLEDs with current, power, and external quantum efficiencies up to 33.0 cd A–1, 32.1 lm W–1, and 16.3%, respectively. This work highlights the significant importance of the noncovalent interactions in designing advanced organic semiconductors for high-performance optoelectronic devices.

Several epidemiological reports demonstrated that vitamin D deficiency elevated risk of preterm delivery. We investigate the effects of oral cholecalciferol (VD3) supplementation on lipopolysaccharide (LPS)-induced preterm delivery. Pregnant mice were randomly assigned to either oral VD3 (25 μg/kg) or corn oil once daily from gestational day (GD)13 to GD15, and were intraperitoneally injected with either LPS (200 μg/kg) or normal saline on GD15. As expected, LPS was effective in inducing preterm delivery and fetal death. LPS-induced preterm delivery and fetal death were alleviated in VD3-pretreated mice. LPS-induced down-regulation of genes for placental progesterone biosynthetic enzymes was blocked in VD3-pretreated mice. LPS-induced reduction of serum progesterone was correspondingly attenuated by VD3. Although oral VD3 had no effect on estradiol production, it attenuated LPS-induced up-regulation of placental ERβ in mice. LPS-induced placental COX-2 up-regulation and serum PGF2α elevation were alleviated in VD3-pretreated mice. Additionally, LPS-evoked elevations of the placental Tnfα, Il1β, Mcp1 and Mip2 mRNAs were attenuated by VD3. VD3 promoted placental vitamin D receptor nuclear translocation and simultaneously alleviated LPS-induced nuclear translocation of NF-κB p65 and p50 subunits. These results provide evidence that oral VD3 supplementation alleviates LPS-induced preterm delivery and fetal demise partially through regulating placental steroid hormones and prostaglandins.

Chemical oxidation and microbial degradation are promising treatments to remediate soils contaminated with persistent organic pollutants. Moderate pre-oxidation is able to enhance the subsequent bioremediation of organic pollutants in soil. In this study, the effects of pre-oxidation on the subsequent biodegradation of benzo[a]pyrene (BaP) were evaluated. The tested oxidants included potassium permanganate (PP) and iron-activated sodium persulfate (PS) at the concentration of 1–40 mmol L−1. The results showed that 20 mmol L−1 PS and 10 mmol L−1 PP treatments had the highest degradation efficiency of BaP in soil, up to 98.7% and 84.2%, without inhibiting subsequent microbial degradation. 10–20 mmol L−1 of the two oxidants significantly promoted viability of microbial community. Especially, PS facilitated the occurrence of more PAHs-degrading microorganisms. The expression of PAH-degradation gene in PS treatment was significantly higher than that in PP treatment (P

ObjectiveVitamin D plays an important role in bone and mineral metabolism. Ultraviolet B (UVB) is the primary determinant for vitamin D synthesis. However, population-based data of vitamin D status was sparse in areas with sunlight deprivation in China. This study aimed to assess serum 25-hydroxyvitamin D [25(OH)D] levels among adult women in Sichuan basin with the lowest sunlight radiation in China, and the associations with sunlight exposure and age.MethodsIn the context of the same ethnicity, similar latitude and lifestyle in sunlight-limited basin and sunlight-abundant plateau, 1,057 women in basin and 337 in plateau aged 29–95 years were included in this study, from November 2012 to February 2013. Daily sunlight exposure duration of previous month was obtained using questionnaires. Serum 25(OH)D was measured by enzyme-linked immunosorbent assay.ResultsThe prevalence of vitamin D severe deficiency [25(OH)D PPConclusionsAlarmingly high prevalence of vitamin D deficiency was observed in women in sunlight-deprived basin in Sichuan. Only the vitamin D status of younger women from plateau with adequate solar radiation could benefit from sunlight exposure. Vitamin D supplementation and vitamin D-fortified food should be encouraged to improve vitamin D status for women living in sunlight-limited areas, or with old age.

This study aimed to investigate whether genotoxic stress mediates arsenic (As)-induced decline in sperm quality. Mice drank ultrapure water containing NaAsO2 (15 mg/L) for 70 days. The mature seminiferous tubules and epididymal sperm count were reduced in As-exposed mice. Cell proliferation, determined by immunostaining with Ki67, was suppressed in As-exposed seminiferous tubules and GC-1 cells. PCNA, a proliferation marker, was reduced in As-exposed mouse testes. Cell growth index was decreased in As-exposed GC-1 cells. Flow analysis showed that As-exposed GC-1 cells were retarded at G2/M phase. CDK1 and cyclin B1 were reduced in As-exposed GC-1 cells and mouse testes. Additional experiment revealed that p-ATR, a marker of genotoxic stress, was elevated in As-exposed mouse testes and GC-1 cells. Accordingly, p-p53 and p21, two downstream molecules of ATR, were increased in As-exposed GC-1 cells. Excess reactive oxygen species (ROS), measured by immunofluorescence, and DNA-strand break, determined by Comet assay, were observed in As-exposed GC-1 cells. γH2AX, a marker of DNA-strand break, was elevated in As-exposed seminiferous tubules and GC-1 cells. NAC alleviated As-evoked DNA damage, genotoxic stress, cell proliferation inhibition and sperm count reduction. In conclusion, ROS-evoked genotoxic stress mediates As-induced germ cell proliferation inhibition and decline in sperm quality.

Increasing evidence suggests that infection promotes the initiation and progression of prostate cancer. This study investigated the effects of lipopolysaccharide (LPS), a major component of Gram-negative bacilli, on proliferation, migration and invasion of prostate cancer cells and the protective effects of 1α,25(OH)2D3 (calcitriol). PC-3 and DU145 cells were stimulated with LPS (2.0 μg/mL) in the presence or absence of 1α,25(OH)2D3 (100 nM). Our results shown that 1α,25(OH)2D3 reduced the proportion of S phase cells in LPS-stimulated PC-3 and DU145 cells, and down-regulated the nuclear protein levels of Cyclin D1 and PCNA in LPS-stimulated PC-3 cells. In addition, 1α,25(OH)2D3 inhibited migration and invasion, as determined by wound healing and transwell assay, in LPS-stimulated PC-3 and DU145 cells. Of interest, we observed that 1α,25(OH)2D3 inhibits NF-κB activation and subsequent synthesis and secretion of IL-6 and IL-8 by promoting VDR and NF-κB p65 interaction. Surprisingly, 1α,25(OH)2D3 blocks nuclear translocation of pSTAT3 by promoting physical interaction between VDR and pSTAT3 (Tyr705) in LPS-stimulated PC-3 and DU145 cells. These results suggest that 1α,25(OH)2D3 inhibits LPS-induced proliferation, migration and invasion in prostate cancer cells by directly and indirectly blocking STAT3 signal transduction.

Rational design and selection of suitable donor and acceptor components for optimal thermally activated delayed fluorescence (TADF) exciplex-type emitters or hosts is presently challenging. Here, we constructed successfully a blue-emitting bulk exciplex system with efficient TADF emission and high triplet energy (ET) based on a donor of 4,4′,4′′-tris [3-methylphenyl(phenyl)amino]triphenylamine and an acceptor of 1,3,5-tri (m-pyrid-3-yl-phenyl)benzene. Systematic experimental and theoretical studies show that the matched frontier orbital energy levels, high ET, facile intersystem crossing, high oscillator strength of the exciplex, and efficient energy transfer channels should be the main considerations during the design of high-performance exciplex-type TADF emitters and bipolar host materials. Therefore, this bulk exciplex system can behave not only as blue emitters for organic light-emitting diodes (OLEDs) but also as universal hosts for the green, yellow, and red phosphorescent OLEDs (PhOLEDs). Impressi...

Osteoporosis is a systemic bone metabolic disease that is highly prevalent in the elderly population, particularly in postmenopausal women, which results in enhanced bone fragility and an increased susceptibility to fractures. However, the underlying molecular pathogenesis mechanisms still remain to be further elucidated. In this study, in a rat ovariectomy- (OVX-) induced postmenopausal osteoporosis model, aberrant expression of a microRNA miR-142-5p and vascular cell adhesion molecule 1 (VCAM-1) was found by RNA sequencing analysis and qRT-PCR. Using a dual-luciferase reporter assay, we found that miR-142-5p can bind to and decrease expression of VCAM-1 mRNA. Such reduction was prohibited when the miR-142-5p binding site in VCAM-1 3'UTR was deleted, and Western blotting analyses validated the fact that miR-142-5p inhibited the expression ofVCAM-1 protein. Bone marrow-derived mesenchymal stem cells (BMMSCs) transfected with miR-142-5p showed a significantly decreased migration ability in a Transwell migration assay. Collectively, these data indicated the important role of miR-142-5p in osteoporosis development involving targeting VCAM-1 and inhibiting BMMSC migration. Refereed/Peer-reviewed

Molybdenum sulfide (MoSx) is a prevalent photocatalytic and electrocatalytic material, attributed to its highly active unsaturated sites. Despite that, its intrinsic activity is still under expectation for large-scale hydrogen evolution reaction (HER). Though the incorporation of Co-promotor could further promote MoSx activity, a tedious preparation is required due to the incompatible properties of Co and Mo. Herein, we report a facile one-step precipitation of cobalt-modified amorphous molybdenum sulfide (Co-MoSx) cocatalyst while focusing on its promotional effects to ZnCdS at λ > 420 nm region. Co-MoSx at different Co/Mo ratios were photochemically-anchored on ZnCdS support through an in-situ light-induced reduction at ambient conditions. In particular, ZnCdS/Co-MoSx (Co/Mo = 1/4, 1 mol%) was emerged as the best formulated photocatalyst, with HER rate and apparent quantum efficiency (AQE) of 551.48 μmol h−1 and 21.7% (420 nm), respectively. While reducing the overpotential for HER, Co-modification could also facilitate the separation of photogenerated electrons and holes for the enhanced HER. Therefore, the reported HER rate of ZnCdS/Co-MoSx is in superior to that of ZnCdS/MoSx and pristine ZnCdS, by 1.4 times and 23 times, respectively. Meanwhile, similar ascendency of Co-MoSx was also observed in its comparison against the benchmarked Pt, Au and Ag co-catalysts. Additionally, the recycling test evinced the satisfactory stability of ZnCdS/Co-MoSx catalyst, with a slightly reduced activity observed after 25 h consecutive HER, marking an average STH of 1.4% under AM 1.5G solar simulator. This work provides a facile way to synthesis Co-modified MoSx co-catalyst that rendered with excellent properties for efficient HER.

High-thermal-conductivity polymers are very sought after for applications in various thermal management systems. Although improving crystallinity is a common way for increasing the thermal conductivity (k) of polymers, it has very limited capacity when the crystallinity is already high. In this work, by heat-stretching a highly crystalline microfiber, a significant k enhancement is observed. More interestingly, it coincides with a reduction in crystallinity. The sample is a Spectra S-900 ultrahigh-molecular-weight polyethylene (UHMW-PE) microfiber of 92% crystallinity and high degree of orientation. The optimum stretching condition is 131.5 °C, with a strain rate of 0.0129 s–1 to a low strain ratio (∼6.6) followed by air quenching. The k enhancement is from 21 to 51 W/(m·K), the highest value for UHMW-PE microfibers reported to date. X-ray diffraction study finds that the crystallinity reduces to 83% after stretching, whereas the crystallite size and crystallite orientation are not changed. Cryogenic thermal characterization shows a reduced level of phonon-defect scattering near 30 K. Polarization Raman spectroscopy finds enhanced alignment of amorphous chains, which could be the main reason for the k enhancement. A possible relocation of amorphous phase is also discussed and indirectly supported by a bending test.

Few studies have investigated posterior reversible encephalopathy syndrome (PRES) in patients with chronic renal failure (CRF). The present study analyzed the clinical manifestations, laboratory examinations and imaging features of PRES in patients with CRF. A total of 42 patients with CRF with or without PRES were recruited in the current retrospective case-control study. Patient data taken prior to the onset of PRES in patients with CRF and PRES (n=21) were collected and analyzed. At the same time, data from patients with CRF but without PRES (n=21) were also analyzed. Brain magnetic resonance imaging (MRI) scans were collected from patients in the PRES group. The mean blood pressure of patients in the PRES group was significantly higher than that of the control group (systolic blood pressure: 172±15 mmHg vs. 135±14 mmHg, P

The composite (LDH/C) of MgAl hydrotalcite and carbon was synthesized in the presence of glucose, which was used as the precursor of the corresponding MgAl mixed oxide (MgAlO C). The as-synthesized hydrotalcites and their corresponding mixed oxides were characterized by XRD, FTIR, SEM, BET/BJH and TG/DTA. The results showed that carbon in the LDH/C could act as a mesoporous template, and the MgAlO C had higher surface areas and more mesopores as well as higher Cr(VI) adsorption performance than the MgAl mixed oxide (MgAlO) prepared in the absence of glucose. The experimental data in the Cr(VI) adsorption by the MgAlO C was analyzed using various adsorption kinetic and thermodynamic models. The pesudo-second order and Elovich models fitted the experimental data. And the intraparticle diffusions model fitted the experimental data well at the second stage of adsorption (>30 min), indicating that the intraparticle diffusion in the Cr(VI) adsorption process was rate-limiting step. Combined with thermodynamic analysis, the activation energy (21.38 kJ·mol−1) suggested that the adsorption process was chemisorption nature. The results demonstrated that the intercalation of CrO42− into the interlyer spaces of the MgAlO C occurred by the reconstruction, and followed by the anion-exchange of interlayer –OH and CrO42− anions companying with diffusion in the entire adsorption process.

We report a systematic investigation of interfacial thermal conductance (Gk) between few to tens -layered mechanical exfoliated molybdenum disulfide (MoS2) and crystalline silicon (c-Si). Based on Raman spectroscopy, we find Gk at room temperature increases with increased layer numbers of MoS2 from 0.974 MW m−2 K−1 to 68.6 MW m−2 K−1. The higher Gk of thicker samples reveals their better interface contact with the substrate, leading to accordingly improved interfacial energy coupling. Molecular dynamics (MD) simulations are conducted to interpret and compare with the experimental observations. MD simulations predict a thermal conductance in the range of 53–77 MW m−2 K−1, which agrees well with the upper bound Gk measured in our work. The thickness dependence of measured Gk reflects the improved interface spacing for thicker MoS2 samples. This phenomenon is further confirmed by the Raman intensity enhancement study by the interface spacing and local optical interference calculations.

Our previous study reported that the Ca-dependent aggregation of polyacrylate-coated TiO2 nanoparticles (PAA-TiO2–NPs) determines their routes of uptake by the waterflea Daphnia magna. Besides the effects of aggregation on NP bioaccumulation, how this process may influence the bioavailability of NP-adsorbed pollutants remains obscure. In the present study, the aggregation of PAA-TiO2–NPs was also adjusted through Ca. Then the accumulation and toxicity of Cd in D. magna were investigated in the presence and absence of the NPs. Although PAA-TiO2–NPs ameliorated Cd toxicity at both low and high Ca concentrations, the underlying mechanisms differed completely. At low Ca, the metal–NP complexes were accumulated by endocytosis and passive drinking, with both pollutants distributed throughout the daphnid. Nevertheless, Cd accumulation was reduced due to its rapid dissociation from the NPs during the endocytosis of the metal–NP complexes. At high Ca, the metal–NP complexes were actively ingested, Cd accumulation ...

1-nitropyrene (1-NP) is a key component of diesel exhaust-sourced fine particulate matter (PM2.5). Our recent study demonstrated that gestational 1-NP exposure caused placental proliferation inhibition and fetal intrauterine growth restriction (IUGR). This study aimed to investigate the role of genotoxic stress on 1-NP-induced placental proliferation inhibition and fetal IUGR. Human trophoblasts were exposed to 1-NP (10 μM). Growth index was reduced and PCNA was downregulated in 1-NP-exposed placental trophoblasts. More than 90% of 1-NP-exposed trophoblasts were arrested in either G0/G1 or G2/M phases. CDK1 and cyclin B, two G2/M cycle-related proteins, and CDK2, a G0/G1 cycle-related protein, were reduced in 1-NP-exposed trophoblasts. Phosphorylated Rb, a downstream molecule of CDK2, was inhibited in 1-NP-exposed trophoblasts. Moreover, DNA double-strand break was observed and γ-H2AX, another indicator of DNA double-strand break, was upregulated in 1-NP-exposed trophoblasts. Phosphorylated ATM, a key molecule of genotoxic stress, and its downstream molecule Chk2 were elevated. By contrast, Cdc25A, a downstream target of Chk2, was reduced in 1-NP-exposed trophoblasts. Phenyl-N-t-butylnitrone (PBN), a free radical scavenger, inhibited 1-NP-induced genotoxic stress and trophoblast cycle arrest. Animal experiment showed that N-acetylcysteine (NAC), an antioxidant, rescued 1-NP-induced placental proliferation inhibition and fetal IUGR in mice. These results provide evidence that reactive oxygen species (ROS)-mediated cellular genotoxic stress partially contributes to 1-NP-induced placental proliferation inhibition and fetal IUGR.

Rapid developments in nanotechnology have led to the release of substantial amounts of nanoparticles (NPs) into aquatic environments, where many types of biotic particles are present and could potentially interact with the NPs. Nevertheless, how biotic particles may affect the bioaccumulation and toxicity of NPs remains largely unknown. In the present study, we investigated the effects of the green alga Chlamydomonas reinhardtii on the accumulation kinetics (uptake, assimilation, efflux) and toxicity of polyacrylate-coated hematite NPs (HemNPs), using Daphnia magna as the test organism. As a biotic particle and daphnid food, C. reinhardtii reduced the accumulation and toxicity of HemNPs in D. magna. The HemNPs were well-dispersed with little adsorption to the alga. Their decreased accumulation could thus be partly explained by their low trophic transfer from the alga to the daphnid and by the inductive effects of the alga on HemNP efflux. However, the main cause was the direct inhibition of HemNP uptake from the water phase as a result of the reduced water-filtration activity of D. magna in the presence of C. reinhardtii. Overall, in bioaccumulation studies, the inhibitory effects of biotic particles on NP uptake from the water phase should be paid attention.

Low vitamin D status is associated with an increased risk of renal cell carcinoma (RCC). This study investigated the association of vitamin D status with serum C-reactive protein (CRP) and adhesion molecules among RCC patients. Fifty newly diagnosed RCC patients and 100 age- and sex-matched controls were recruited. As expected, serum 25(OH)D level was lower in RCC patients than in controls. By contrast, serum levels of CRP, an inflammatory molecule, and ICAM, LAMA4 and EpCAM, three adhesion molecules, were higher in RCC patients than in controls. All RCC patients were divided into two groups: H-VitD (>20 ng/ml) or L-VitD (in vitro experiments found that VitD3 suppressed NF-κB activation and adhesion molecules in RCC cells. Moreover, VitD3 suppressed NF-κB through reinforcing physical interaction between VDR and NF-κB p65 subunit in RCC cells. These results provide a mechanistic explanation for the association among low vitamin D status, local inflammation and increased expression of adhesion molecules among RCC patients.

It is increasingly recognized that excessive glucocorticoids induce fetal intrauterine growth restriction (IUGR). Placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), a glucocorticoid-catalyzing enzyme, prevents active glucocorticoids from maternal circulation into the fetus, thus protecting against IUGR. Previous studies demonstrated gestational LPS exposure caused fetal IUGR. The aim of the current study was to investigate the effects of LPS on 11β-HSD2 in mice placentas and human placental trophoblasts. Pregnant ICR(CD-1) mice were i.p. injected with LPS (200 μg/kg) on gestational day 16. As expected, gestational LPS exposure downregulated 11β-HSD2 in mice placentas. In vitro, LPS downregulated 11β-HSD2 in human placental trophoblasts. Additional experiment showed that LPS, which activated NF-κB, suppressed rosiglitazone-induced activation of peroxisome proliferator–activated receptor-γ (PPARγ) in mice placentas and human placental trophoblasts. Moreover, NF-κB p65 knockdown and specific NF-κB inhibitor attenuated LPS-induced suppression of PPARγ nuclear translocation in human placental trophoblasts. In addition, NF-κB p65 knockdown attenuated LPS-induced downregulation of 11β-HSD2 in human placental trophoblasts. Mechanically, LPS promoted physical interaction between NF-κB p65 and PPARγ in the cytoplasm and nucleus of placental trophoblasts. Finally, pretreatment with rosiglitazone, a PPARγ agonist, partially alleviated LPS-induced reduction of fetal weight and crown-rump length. Taken together, these results suggest that LPS downregulates 11β-HSD2 through suppressing PPARγ in placental trophoblasts. Placental 11β-HSD2 downregulation may contribute partially to LPS-induced fetal IUGR.

Background. Cellular stress is involved in ischemia/reperfusion- (I/R-) induced acute kidney injury (AKI). This study is aimed at investigating the effects of pretreatment with cholecalciferol on renal oxidative stress and endoplasmic reticulum (ER) stress during I/R-induced AKI. Methods. I/R-induced AKI was established by cross-clamping renal pedicles for 90 minutes and then reperfusion. In the Chol+I/R group, mice were orally administered with three doses of cholecalciferol (25 μg/kg) at 1, 24, and 48 h before ischemia. Renal cellular stress and kidney injury were measured at different time points after reperfusion. Results. I/R-induced AKI was alleviated in mice pretreated with cholecalciferol. In addition, I/R-induced renal cell apoptosis, as determined by TUNEL, was suppressed by cholecalciferol. Additional experiment showed that I/R-induced upregulation of renal GRP78 and CHOP was inhibited by cholecalciferol. I/R-induced renal IRE1α and eIF2α phosphorylation was attenuated by cholecalciferol. Moreover, I/R-induced renal GSH depletion, lipid peroxidation, and protein nitration were blocked in mice pretreated with cholecalciferol. I/R-induced upregulation of renal NADPH oxidases, such as p47phox, gp91phox, and nox4, was inhibited by cholecalciferol. I/R-induced upregulation of heme oxygenase- (HO-) 1, gshpx and gshrd, was attenuated in mice pretreated with cholecalciferol. Conclusions. Pretreatment with cholecalciferol protects against I/R-induced AKI partially through suppressing renal cellular stress response.

Several epidemiological studies reported that chronic arsenic exposure increased risk of prostate cancer. This study aimed to investigate whether chronic NaAsO2 exposure elevates stemness and chemoresistance in prostate cancer cells. DU145 (wild-type p53) and PC-3 (p53-null) cells were exposed to NaAsO2 (2 μmol/L) for 30 generations. IC50s to docetaxel and cisplatin were increased in NaAsO2-exposed DU145 and PC-3 cells. The number of tumor spheres was elevated in NaAsO2-exposed DU145 and PC-3 cells. Nanog, SOX-2 and ALDH1A1, three markers of cancer stemness, were upregulated in NaAsO2-exposed PC-3 spheres. Moreover, NaAsO2-exposed DU145 and PC-3 cells were arrested in G2/M phase. Histone H2AX phosphorylation on Ser139, an indicator for DNA double-strand break, was upregulated in NaAsO2-exposed DU145 and PC-3 cells. ATM phosphorylation on Ser1981, a key sensor of genotoxic stress, was rapidly elevated in NaAsO2-exposed DU145 cells. Phosphor-p53, a downstream molecule of ATM signaling, and p21, a direct target of p53, were upregulated in NaAsO2-exposed DU145 cells. Unexpectedly, p21 was also elevated in NaAsO2-exposed p53-null PC-3 cells. Antioxidant NAC alleviated NaAsO2-induced ATM phosphorylation, cell cycle arrest, and subsequent stemness enhancement and chemoresistance in both DU145 and PC-3 cells. These results suggest that ROS-mediated genotoxic stress is involved in NaAsO2-induced cell cycle arrest, stemness enhancement and chemoresistance of prostate cancer cells in a p53-independent manner.

Organophosphorus pesticides (OPPs) are used worldwide and pose great risks to human health. However, information on their presence in agricultural soils at regional scale and the associated risks is limited. In this study, an extensive investigation on agricultural soils was conducted throughout the Yangtze River Delta (YRD) of China to reveal the status of OPP pollution. The total concentrations of the nine OPPs ranged from

Silicon-containing ultrahigh-energy gap hosts (UGHs) have emerged as important candidates of high-performance host materials with high thermal stability and triplet energy for blue phosphorescent organic light-emitting diodes (PhOLEDs). However, the highest occupied molecular orbital (HOMO) of these UGHs are generally too deep to support balanced hole injection and transportation in devices. Here, we propose a new design strategy of UGHs by multiple introduction of strong electron-donating and high-triplet-energy units of carbazoles into the electron-accepting arylsilanes in the N–Si–N structure. The facilely synthesized carbazole-arylsilanes in one-step show high thermal stability, triplet energy and charge mobilities with high-lying HOMOs due to enhanced σ–π conjugation in the N–Si–N structure as revealed by combined experimental and theoretical investigations. Impressively, blue PhOLEDs hosted by these novel N–Si–N bonded UGHs exhibit an improved maximum current efficiency up to 39.5 cd A−1, a power efficiency of 27.4 lm W−1, and an external quantum efficiency of 24.2%, demonstrating significant advances in the design of UGHs by adjusting the d-orbital participation of π-conjugation to enhance the σ–π conjugation in donor (D)–acceptor (A) molecular architectures.

Selective tuning of optoelectronic properties of organic semiconductors is one of the most significant challenges in organoelectronics. Herein, on the basis of aryl phosphine sulfide (APS), we show that the electronic performance can be selectively enhanced by evoking the non-bonding S-π interactions between the sulfur atom of APS and π-conjugated carbazole moiety, on account of the large scope 3p lone-pair electrons of S for effective electronic communications. It is indicated that the material properties and device performances are strongly dependent on the beingness of the successfully established intramolecular S-π interaction. Specifically, APS-based DPSSi exhibits excellent solubility and film-forming ability and enhanced carrier transportation and injection abilities at high triplet energy level; and the DPSSi-hosted blue phosphorescent light-emitting diodes (PhOLEDs) show high current efficiency up to 36.6 cd A−1, power efficiency of 30.6 lm W−1, and external quantum efficiency of 20.8%, which are among the best results of blue PhOLEDs reported so far. The semi-conjugation feature of S-π interaction in selectively modulating electronic properties would offer exciting opportunities for settling intrinsic difficulties of organic optoelectronic materials and devices, promoting significantly the development of non-bonding interaction involved organic optoelectronic molecules.

Graphitic carbon nitride (g-C3N4) has attracted enormous interest because of its prominent photocatalytic performance. Due to the planar π conjugation structure which should provide good binding energy for adsorption of metal atoms including lithium (Li) and sodium (Na), g-C3N4 also possesses great application potential in ion batteries. Here, first-principles calculations are performed to investigate its application in lithium ion batteries (LIBs), focusing on the electric field effect on the Li storage. Our results revealed that Li adsorbed C3N4 (Li–C3N4) exhibits good modulation of its Li binding energy by applying external vertical electric field. The Bader charge analysis and charge density difference calculations provide a deep insight into the tunable Li adsorption to C3N4 sheets. Our theoretical results suggest that C3N4 is a suitable anode material for LIBs.

Two new building blocks of perylene-embedded benzoazoles containing both rigid 2D-conjugated aromatic rings and flexible branched alkyl chains were designed and facilely synthesized in high yields for organic solar cells (OSCs). With a typical acceptor of diketopyrrolopyrrole, small molecular OSC donors constructed in an acceptor-fused donor–acceptor motif exhibit excellent solubility, stability, and light absorption with tunable frontier orbitals, leading to a power conversion efficiency of up to 2.88% in preliminary OSCs.

Optical methods are promising tools for small-scale thermal probing and characterization. A lab-developed photothermal (PT) technique provides a noncontact method to characterize the thermal transport along the thickness direction of a multilayered film by analyzing the phase shift of the thermal radiation from the sample’s surface. Aiming to reduce the calibration in the phase shift method, a new amplitude method is developed on the basis of the amplitude of the thermal radiation signal. The new method successfully performs the thermal measurements for chemical vapor deposited SiC films, thermally oxidized SiO2 film on silicon substrates, and spider silk films. Furthermore, weak-sensitivity to the thermal contact resistance enables the amplitude method to lower the effect of thermal contact resistance on thermal conductivity determination. The normalized amplitude ratio of a high frequency to a low frequency provides a reliable way to evaluate the effusivity ratio of the film to that of the substrate. For spider silk films, the contribution to the thermal conductivity from -helices and antiparallel -sheets in silk proteins against the temperature has been studied. Raman spectroscopy is better than PT since its scatterings involve not only the structure information of a sample but also physical properties, like temperature and stress. The edge area of a mechanically cleaved Si wafer is studied using Raman spectroscopy. The appearance of nanocrystals there is proved and it accounts for the abnormal increase in Raman intensity when the grain size of nanocrystals varies from 20 to 10 nm. For transient thermal probing and characterization, a time-domain differential Raman technique is developed using a square-wave modulated laser. The varying duty cycle of the modulation signal realizes controlled heating and

It is increasingly recognized that farnesoid X receptor (FXR) has anti-inflammatory and antioxidant activities. The present study investigated the effects of obeticholic acid (OCA), a novel synthetic FXR agonist, on renal inflammation and oxidative stress in a model of sepsis-induced acute kidney injury. All mice except controls were intraperitoneally injected with lipopolysaccharide (LPS, 2.0 mg/kg). In the OCA + LPS group, mice were orally pretreated with three doses of OCA (5 mg/kg) at 48, 24 and 1 h before LPS injection. Interestingly, OCA pretreatment alleviated LPS-induced renal dysfunction and pathological damage. Moreover, OCA pretreatment repressed renal inflammatory cytokines and chemokines during LPS-induced acute kidney injury. In addition, OCA blocked nuclear translocation of nuclear factor kappa B (NF-κB) p65 and p50 subunits in tubular epithelial cells of renal cortex. Additional experiment showed that OCA pretreatment attenuated LPS-induced renal glutathione depletion, lipid peroxidation and protein nitration. Moreover, OCA pretreatment inhibited the upregulation of renal NADPH oxidase and inos genes during LPS-induced acute kidney injury. In conclusion, OCA pretreatment protects against sepsis-induced acute kidney injury through inhibiting renal inflammation and oxidative stress. These results provide evidence for roles of FXR as an important regulator of inflammation and oxidative stress in the kidney.

A simple and rapid sensing strategy was proposed for chloramphenicol (CAP) detection based on structure-switching signaling aptamers. In this protocol, the aptamer can bind to both the fluorophore (FAM)-labeled complementary strand and the quencher (BHQ1)-labeled complementary strand, thus leading to the effective quenching of FAM fluorescence by BHQ1. However, when CAP is present, the structure switch is reversed because the aptamer recognizes CAP, resulting in fluorescence recovery. Such a fluorescence-sensing platform can monitor CAP within a good linear range (1–100 ng/mL), with a detection limit of 0.70 ng/mL. Cross-reactivity with other common antibiotics is negligible, indicating the excellent selectivity of the strategy. Moreover, as the aptamers are not modified, this method is simple and low-cost. The present work reveals a new direction for detecting CAP or other target compounds without prior knowledge of the secondary or tertiary structures of the aptamer.

The exponential growth of utilizing synthetic organic molecules in optoelectronic applications poses strong demands for rational control over the excited states of the materials. The manipulation of excited states through molecular design has led to the development of high-performance optoelectronic devices with tunable emission colors, high quantum efficiencies and efficient energy/charge transfer processes. Recently, a significant breakthrough in lifetime tuning of excited states has been made; the purely organic molecules were found to have ultralong-lived excited state under ambient conditions with luminescence lifetimes up to 1.35 s, which are several orders of magnitude longer than those of conventional organic fluorophores. Given the conceptual advance in understanding the fundamental behavior of excited state tuning in organic luminescent materials, the investigations of organic ultralong room-temperature phosphorescence (OURTP) should provide new directions for researches and have profound impacts on many different disciplines. Here, we summarized the recent understandings on the excited state tuning, the reported OURTP molecules and their design considerations, the spectacular photophysical performance, and the amazing optoelectronic applications of the newly emerged organic optoelectronic materials that free of heavy metals.

Computational investigations of Cu(I)-catalyzed CN coupling between aryl halides and aqueous ammonia without addition of any base or ligand were reported. Density functional theory calculations were performed to reveal the mechanism of the ligand-free amination reaction for the preparation of primary aromatic amines. Through systematic evaluation of the relative concentrations of possible Cu species in solution, we propose that the active catalyst is the neutral Cu(I) complexes rather than the Cu(I) cations; oxidative addition of aryl bromide is a facile step of the catalytic cycle; reactant (NH3) and solvent molecule (NMP) can act as ligands of Cu species to help reduce the activation energy of the forward reaction and increase the activation energy of the reverse reaction; except for Pathway B, the deprotonation step is irreversible due to the extreme exothermic feature; the elimination of H2O is kinetically favored, while that of HBr is thermodynamically preferred. These findings should be valuable for the mechanism understandings of the ligand-free Cu-catalyzed CN cross-coupling reactions and for the further development of highly efficient amination catalyst systems.

Increasing evidence demonstrates that reactive oxygen species plays important roles in sepsis-induced acute kidney injury. This study investigated the effects of VitD3 pretreatment on renal oxidative stress in sepsis-induced acute kidney injury. Mice were intraperitoneally injected with lipopolysaccharide (LPS, 2.0mg/kg) to establish an animal model of sepsis-induced acute kidney injury. In VitD3+LPS group, mice were orally pretreated with three doses of VitD3 (25 μg/kg) at 1, 24 and 48 h before LPS injection. As expected, oral pretreatment with three daily recommended doses of VitD3 markedly elevated serum 25(OH)D concentration and efficiently activated renal VDR signaling. Interestingly, LPS-induced renal GSH depletion and lipid peroxidation were markedly alleviated in VitD3-pretreated mice. LPS-induced serum and renal nitric oxide (NO) production was obviously suppressed by VitD3 pretreatment. In addition, LPS-induced renal protein nitration, as determined by 3-nitrotyrosine residue, was obviously attenuated by VitD3 pretreatment. Further analysis showed that LPS-induced up-regulation of renal inducible nitric oxide synthase (inos) was repressed in VitD3-pretreated mice. LPS-induced up-regulation of renal p47phox and gp91phox, two NADPH oxidase subunits, were normalized by VitD3 pretreatment. In addition, LPS-induced down-regulation of renal superoxide dismutase (sod) 1 and sod2, two antioxidant enzyme genes, was reversed in VitD3-pretreated mice. Finally, LPS-induced tubular epithelial cell apoptosis, as determined by TUNEL, was alleviated by VitD3 pretreatment. Taken together, these results suggest that VitD3 pretreatment alleviates LPS-induced renal oxidative stress through regulating oxidant and antioxidant enzyme genes.

Small molecules with functional groups can show different electron affinity and binding behavior on nanocrystal surface, which in principle could be used to alternate the electrical transport in self-assembled nanocrystal thin films. These small molecules can also serve for scattering the phonons to reduce the thermal conductivity. Here, we present our research on the thermoelectric characteristic of self-assembled silver telluride (Ag2Te) nanocrystal thin films that are fabricated by a layer-by-layer (LBL) dip-coating process. We perform investigations on the electrical conductivity and Seebeck coefficient on the Ag2Te nanocrystal thin films containing hydrazine, 1,2-ethanedithiol, and ethylenediamine between 300 and 400 K. We also use photothermal (PT) technique to obtain the thermal conductivity of the films at room temperature and estimate the thermoelectric figure of merit (ZT). The experimental results suggest that the surface-bound small molecules could serve as a beneficial component to build nano...

With the emergence and rapid deployment of PV (photovoltaic) facades, a comparison among see-through amorphous silicon (a-Si) PV glazings and traditional glazings under different architectural conditions could provide us a broader perspective for comprehending the energy performance and utilisation of see-through a-Si PV glazing in BIPV (building integrated photovoltaic) applications. In this paper, two see-through a-Si PV glazings of different transmittance are investigated and compared with three traditional glazings in terms of PV electricity generation and energy consumption during lighting, cooling, and heating in China. The impacts of the architectural conditions are considered in the study, particularly with respect to five factors: room depth, room height, room width, window height, and WWR (window-to-wall ratio). A calculation model for a see-through a-Si PV glazing is developed and validated with field experiments to perform simulations using Energy Plus. The results indicate that see-through a-Si PV glazings have great potential and exhibit better energy performance than single and double glazings, where cooling energy consumption is the dominant factor. The results also suggest that see-through a-Si PV glazings are more beneficial than traditional glazings when they are applied in shallow rooms with large windows or high ceilings.

In this work, we report the preparation and electrochemical responses of Au disk nanoelectrodes as small as 5 nm in radii by the improvement of the laser-assisted pulling technique. A Au microwire is sealed into a bilayer capillary and pulled into an ultrasharp Au nanowire sealed in a silica tip using a laser-assisted puller. The ultrasharp tip is then sealed into a piece of glass tube, which is manually polished to expose the Au. Transmission electron microscopy, steady-state voltammetry of small redox species (e.g., ferrocene (Fc), ferrocene methanol (FcH2OH), potassium ferricyanide (Fe(CN)63−), hexaammineruthenium(III)chloride (Ru(NH3)63+)), and cyclic voltammetry in a H2SO4 solution are utilized to characterize the nanoelectrodes. The heterogeneous electron transfer rate constants for the oxidation/reduction of Fc, FcH2OH, Fe(CN)63−, and Ru(NH3)63+ are determined from steady-state voltammetry using the method developed by Mirkin and Bard and found to be ko = 7.9 ± 3.6 cm s−1 and α = 0.41 ± 0.04 for Fc, ko = 7.4 ± 7.1 cm s−1 and α = 0.41 ± 0.23 for FcCH2OH, ko = 4.0 ± 3.6 cm s−1 and α = 0.52 ± 0.17 for Fe(CN)63−, and ko = 7.2 ± 6.9 cm s−1 and α = 0.53 ± 0.22 for Ru(NH3)63+. These Au disk nanoelectrodes have been used to investigate the direct electrochemistry of ferritin molecules, which are immobilized on the Au surface by an electrostatic interaction between the cysteamine monolayer modified on the Au surface and ferritin molecules. From the voltammetric peak of ferritin on the Au nanoelectrode (200 nm in radius), the amount of ∼3900 molecules or 6.1 zmol can be calculated.

We studied arsenite (iAs(III)) accumulation, oxidation, and toxicity in the freshwater green alga Chlamydomonas reinhardtii under nutrient-enriched (+NP), phosphorus-limited (-P), and nitrogen-limited (-N) conditions. The -P alga (55.1 μM) had a Michaelis constant (Kd) for uptake approximately one tenth of the +NP (419 μM) and -N (501 μM) cells, indicating iAs(III) uptake inhibition by extracellular phosphate. This conclusion was supported by the hyperbolic reduction in iAs(III) uptake rate (V) from 9.2 to 0.8 μmol/g-dw/h when the extracellular phosphate concentration went up from 0 to 250 μM. The maximal iAs(III) uptake rate (Vmax) of the -N alga (24.3 μmol/g-dw/h) was twice as much as that of the +NP (12 μmol/g-dw/h) and -P (8.1 μmol/g-dw/h) cells. It implies that more arsenic transporters were synthesized under the -N condition. Once accumulated, iAs(III) was oxidized and a higher proportion of arsenate (iAs(V)) was observed at lower [As]dis or under nutrient-limited conditions. Nevertheless, iAs(III) oxidation mainly occurred outside the cells with the extent of oxidation reciprocal to [As]dis. Based on the logistic modeling of the concentration-response curves in the +NP, -P, and -N toxicity tests, iAs(III) had an [As]dis-based EC50 of 1763, 13.1, and 1208 μM and an intracellular arsenic concentration based EC50 of 35.6, 28.8, and 195 μmol/g-dw, respectively. Higher iAs(III) toxicity to the -P cells occured because of their increased iAs(III) accumulation, whereas the underlying mechanisms why the -N alga was more tolerant need to be further revealed. Overall, both N and P had remarkable effects on the behavior and effects of iAs(III), which cannot be disregarded in the biogeochemical cycling research of arsenic.