Tuning the Absorption, Fluorescence, Intramolecular Charge Transfer, and Intersystem Crossing in Spiro[fluorene]acridinone

In this work, we prepared a series of electron donor-acceptor systems based on spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO). Our SFDBAOs consist of orthogonally positioned fluorenes and aromatic ketones. By fine-tuning the substitution of electron-donating pyrenes, the complex interplay among different excited-state decay channels and the overall impact of solvents on these decay channels were uncovered. Placing pyrene, for example, at the aromatic ketones resulted in a profound solvatochromism in the form of a bright charge-transfer (CT) emission spanning from yellow to red-NIR. In contrast, a dark non-emissive CT was noted upon pyrene substitution at the fluorenes. In apolar solvents, efficient triplet-excited state generation was observed for all SFDBAOs. Either charge transfer was concluded to mediate the intersystem crossing (ISC) in the case of pyrene substitution or the El-Sayed rule was applicable when lacking pyrene substitution as in the case of SFABAO. In polar solvents, charge separation is the sole decay upon pyrene substitution. Moreover, competition between ISC and CT lowered the triplet-excited state generation in SFDBAO.

Catalyzing Singlet Fission by Transition Metals: Second versus Third Row Effects

The synthesis and characterization of platinum(II) and palladium(II) complexes bearing two (dimers Pt(Lpc)2Cl2 and Pd(Lpc)2Cl2), one (monomers Pt(Lpc)(Lref)Cl2 and Pd(Lpc)(Lref)Cl2), or no (reference compounds Pt(Lref)2Cl2 and Pd(Lref)2Cl2) pentacene-based pyridyl ligands are presented. Photophysical properties of the dimers are probed by means of steady-state and time-resolved transient absorption measurements in comparison to the monomer and model compounds. Our results document that despite enhanced spin-orbit coupling from the presence of heavy atoms, intramolecular singlet fission (iSF) is not challenged by intersystem crossing. iSF thus yields correlated triplet pairs and even uncorrelated triplet excited states upon decoherence. Importantly, significant separation of the two pentacenyl groups facilitates decoupling of the two chromophores. Furthermore, the mechanism of iSF is altered depending on the respective metal center, that is, Pt(II) versus Pd(II). The dimer based on Pt(II), Pt(Lpc)2Cl2, exhibits a direct pathway for the iSF and forms a correlated triplet pair with singlet-quintet spin-mixing within 10 ns in variable solvents. On the other hand, the dimer based on Pd(II), Pd(Lpc)2Cl2, leads to charge transfer mixing during the population of the correlated triplet pair that is dependent on solvent polarity. Moreover, Pd(Lpc)2Cl2 gives rise to a stable equilibrium between singlet and quintet correlated triplet pairs with lifetimes of up to 170 ns. Inherent differences in the size and polarizability, when contrasting platinum(II) with palladium(II), are the most likely rationale for the underlying trends.

One-Pot Synthesis and Excited-State Dynamics of Null Exciton-Coupled Diketopyrrolopyrroles Oligo-Grids

Exciton coupling in molecular aggregates plays a vital role in impacting and fine-tuning optoelectronic materials and their efficiencies in devices. A versatile platform to decipher aggregation-property relationships is built around multichromophoric architectures. Here, a series of cyclic diketopyrrolopyrrole (DPP) oligomers featuring nanoscale gridarene structures and rigid bifluorenyl spacers are designed and synthesized via one-pot Friedel-Crafts reaction. DPP dimer [2]Grid and trimer [3]Grid, which are cyclic rigid nanoarchitectures of rather different sizes, are further characterized via steady-state and time-resolved absorption and fluorescence spectroscopies. They exhibit monomer-like spectroscopic signatures in the steady-state measurements, from which null exciton couplings are derived. Moreover, in an apolar solvent, high fluorescence quantum yields and excited-state dynamics that resembled DPP monomer are gathered. In a polar solvent, the localized singlet excited state on a single DPP dissociates into the adjacent null coupling DPP with charge transfer characteristics. This pathway facilitates the evolution of the symmetry-broken charge-separated state (SB-CS). Notable is the fact that the SB-CS of [2]Grid is, on one hand, in equilibrium with the singlet excited state and promotes, on the other hand, the formation of the triplet excited state with a yield of 32% via charge recombination.

Tetracene Dimers: A Platform for Intramolecular Down- and Up-conversion

Photon energy conversion can be accomplished in many different ways, including the two opposing manners, down-conversion (i.e., singlet fission, SF) and up-conversion (i.e., triplet-triplet annihilation up-conversion, TTA-UC). Both processes have the potential to help overcome the detailed balance limit of single-junction solar cells. Tetracene, in which the energies of the lowest singlet excited state and twice the triplet excited state are comparable, exhibits both down- and up-conversion. Here, we have designed meta-diethynylphenylene- and 1,3-diethynyladamantyl-linked tetracene dimers, which feature different electronic coupling, to characterize the interplay between intramolecular SF (intra-SF) and intramolecular TTA-UC (intra-TTA-UC) via steady-state and time-resolved absorption and fluorescence spectroscopy. Furthermore, we have used Pd-phthalocyanine as a sensitizer to enable intra-TTA-UC in the two dimers via indirect photoexcitation in the near-infrared part of the solar spectrum. The work is rounded off by temperature-dependent measurements, which outline key aspects of how thermal effects impact intra-SF and intra-TTA-UC in different dimers.

Interfullerene Electronic Interactions and Excited-State Dynamics in Fullerene Dumbbell Conjugates

Several dumbbell conjugates featuring M₃N@I_h-C₈₀ (M = Sc, Y) and C₆₀ were prepared to systematically investigate interfullerene electronic interactions and excited state dynamics. From electrochemical investigations, we concluded that the redox potentials of our M₃N@I_h-C₈₀ (M = Sc, Y) dumbbells depend largely on the interfullerene electronic interactions. Assisted by DFT calculation, the unique role of metal atoms was highlighted. Most importantly, ultrafast spectroscopy experiments revealed symmetry-breaking charge separation in Sc₃N@C₈₀-dumbbell to yield an unprecedented (Sc₃N@C₈₀)^•+-(Sc₃N@C₈₀)^•- charge separated state. This is, to the best of our knowledge, the first time that symmetry-breaking charge separation following photoexcitation is corroborated in a fullerene system. As such, our work shed light on the significance of interfullerene electronic interactions and their uniqueness for modulating excited state properties.

Understanding the Visible Absorption of Electron Accepting and Donating CNDs

Carbon nanodots (CNDs) synthesized from citric acid and formyl derivatives, that is, formamide, urea, or N-methylformamide, stand out through their broad-range visible-light absorbance and extraordinary photostability. Despite their potential, their use has thus far been limited to imaging research. This work has now investigated the link between CNDs' photochemical properties and their chemical structure. Electron-rich, yellow carbon nanodots (yCNDs) are obtained with in situ addition of NaOH during the synthesis, whereas otherwise electron-poor, red carbon nanodots (rCNDs) are obtained. These properties originate from the reduced and oxidized dimer of citrazinic acid within the matrix of yCNDs and rCNDs, respectively. Remarkably, yCNDs deposited on TiO₂ give a 30% higher photocurrent density of 0.7 mA cm^-2 at +0.3 V versus Ag/AgCl under Xe-lamp irradiation (450 nm long-pass filter, 100 mW cm^-2 ) than rCNDs. The difference in overall photoelectric performance is due to fundamentally different charge-transfer mechanisms. These depend on either the electron-accepting or the electron-donating nature of the CNDs, as is evident from photoelectrochemical tests with TiO₂ and NiO and time-resolved spectroscopic measurements.

Altering singlet fission pathways in perylene-dimers; perylene-diimide versus perylene-monoimide

We used a systematic approach to shed light on the inherent differences in perylenes, namely monoimides versus diimides, including coplanarity and dipole moment, and their impact on singlet fission (SF) by designing, synthesizing, and probing a full fledged series of phenylene- and naphthalene-linked dimers. Next to changing the functionality of the perylene core, we probed the effect of the spacers and their varying degrees of rotational freedom, molecular electrostatic potentials, and intramolecular interactions on the SF-mechanism and -efficiencies. An arsenal of spectroscopic techniques revealed that for perylene-monoimides, a strong charge-transfer mixing with the singlet and triplet excited states restricts SF and yields low triplet quantum yields. This is accompanied by an up-conversion channel that includes geminate triplet-triplet recombination. Using perylene-diimides alters the SF-mechanism by populating a charge-separated-state intermediate, which either favors or shuts-down SF. Napthylene-spacers bring about higher triplet quantum yields and overall better SF-performance for all perylene-monoimides and perylene-diimides. The key to better SF-performance is rotational freedom because it facilitates the overall excited-state polarization and amplifies intramolecular interactions between chromophores.

Impact of nodular calcification on the outcomes of patients with acute coronary syndrome (ACS) treated with primary percutaneous coronary intervention (PCI)

Background

Calcified plaque is thought to adversely impact clinical outcomes but the impact of nodular calcification after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) remains unclear.

Purpose

This study sought to explore the impact of nodular calcification on the outcomes of patients undergoing percutaneous coronary intervention for acute coronary syndromes.

Methods

Five-hundred culprit plaque with calcification were analysed from 495 ACS patients in whom PCI was performed. Plaques were divided into nodular calcification group (n=238) and non-nodular calcification group (n=262). Calcification is defined as an area with low back-scattering signal and a sharp border. Nodular calcification was defined as a protruding mass with an irregular surface, high backscattering, and signal attenuation on optical coherence tomography (OCT).

Results

Patients with nodular calcification were older (p<0.001) and had lower left ventricular ejection fraction (p=0.006) compared to patients with non-nodular calcification. Lesion length (31 (25.2, 38.5) vs. 29 (22.8, 34.1), p<0.001) was longer in plaques with nodular calcification. A higher prevalence of superficial calcium (p<0.001) was observed in plaques with nodular calcification compared with non-nodular calcification group. Minimum stent area (MSA) (5.0 (3.9, 6.3) vs. 5.4 (4.2, 6.7), p=0.011) and stent expansion (70 (62.7, 81.8) vs. 75 (65.2, 86.6), p=0.004) were significantly smaller in the nodular calcification group than in the non-nodular calcification group. Independent predictors of nodular calcification were age (p<0.001) lesion length (p=0.002) and calcium depth (p<0.001).

Conclusion

This study demonstrated that the presence of nodular calcification is associated with unfavourable outcomes with smaller minimum stent area and higher incidence of stent under expansion in patients with ACS treated with primary PCI.

Funding Acknowledgement

Type of funding sources: None.

Improvement of the Irrigation Scheme in the ORCHIDEE Land Surface Model and Impacts of Irrigation on Regional Water Budgets Over China

In China, irrigation is widespread in 40.7% cropland to sustain crop yields. By its action on water cycle, irrigation affects water resources and local climate. In this study, a new irrigation module, including flood and paddy irrigation technologies, was developed in the ORCHIDEE-CROP land surface model which describes crop phenology and growth in order to estimate irrigation demands over China from 1982 to 2014. Three simulations were performed including NI (no irrigation), IR (with irrigation limited by local water resources), and FI (with irrigation demand fulfilled). Observations and census data were used to validate the simulations. Results showed that the estimated irrigation water withdrawal ( W ) based on IR and FI scenarios bracket statistical W with fair spatial agreements ( r = 0 . 68 ± 0 . 07 ; p < 0 . 01 ). Improving irrigation efficiency was found to be the dominant factor leading to the observed W decrease. By comparing simulated total water storage (TWS) with GRACE observations, we found that simulated TWS with irrigation well explained the TWS variation over China. However, our simulation overestimated the seasonality of TWS in the Yangtze River Basin due to ignoring regulation of artificial reservoirs. The observed TWS decrease in the Yellow River Basin caused by groundwater depletion was not totally captured in our simulation, but it can be inferred by combining simulated TWS with census data. Moreover, we demonstrated that land use change tended to drive W locally but had little effect on total W over China due to water resources limitation.

Dietary vitamin C intake and the risk of hip fracture: a dose-response meta-analysis

The meta-analysis suggested that dietary vitamin C was statistically inversely associated with the risk of hip fracture (overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%) and with the increase of 50 mg/day vitamin C intake, the risk of hip fracture will reduce by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05).

INTRODUCTION

Previous studies had inconsistent findings regarding the association between vitamin C intake and the risk of hip fracture. Therefore, we conducted a meta-analysis to evaluate the association of dietary vitamin C intake and the risk of hip fracture.

METHODS

Relevant studies were identified by searching PubMed, Embase, and Web of Science up to December 2016. Additional articles were identified from reviewing the reference lists of relevant articles. The summary relative risks (RRs) or odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by random effects model. Funnel plot and Egger's test were used to test publication bias.

RESULTS

The total six articles containing 7908 controls and 2899 cases of hip fracture were included in this meta-analysis. By comparing the highest versus the lowest categories of vitamin C intake, we found that dietary vitamin C was statistically correlated with the risk of hip fracture [overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%]. A linear dose-response association showed that the increase with vitamin C intake of 50 mg/day statistically reduced by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05) the risk of hip fracture.

CONCLUSIONS

In conclusion, the results of current meta-analysis strongly support that increasing dietary vitamin C intake can decrease the risk of hip fracture. In order to verify the association of vitamin C intake and hip fracture risk, further well-designed largely randomized controlled trials (RCTs) are needed.

Efficacy study and field application of an inactivated new type gosling viral enteritis virus vaccine for domestic geese

New type gosling viral enteritis virus (NGVEV) caused a serious disease in naive juvenile goslings. In the described studies the performance of 2 vaccines was analyzed: a vaccine containing adjuvanted inactivated NGVEV and a vaccine containing adjuvanted inactivated NGVEV and recombinant goose IL-2. Breeder geese were subcutaneously vaccinated at the beginning of the egg production period with the vaccines. Breeder geese sham vaccinated with PBS served as control. The cellular and humoral immune responses of the vaccinated breeder geese, as well as the presence of maternally derived antibody to NGVEV, were investigated by ELISA, virus neutralization test, and lymphocyte proliferation assay, respectively. A significantly higher immunogenicity (P < 0.05) was induced by the inactivated NGVEV-recombinant goose IL-2 adjuvant vaccine compared with the inactivated NGVEV vaccine. The offspring of the vaccinated birds were challenged with virulent NGVEV (100 50% lethal dose) and the protective efficacy of the vaccines was determined. Furthermore, in a field trial the efficacy of the inactivated NGVEV vaccine was recorded from years 2003 to 2007. No clinical signs or abnormal health status were observed in the vaccinated breeder geese and the progeny. After a single application, >80% protection was shown in the progeny of geese vaccinated against NGVEV challenge for approximately 5 mo. The extensive field trials further demonstrated that vaccination of breeder geese with the inactivated NGVEV vaccine could be a safe and efficacious means to control NGVE disease. Moreover, the level of maternally derived NGVEV antibody titer in the egg yolk reflected the level of NGVEV antibodies in the breeder geese, suggesting that the egg yolk could be used to monitor the vaccination efficacy in commercial goose breeder flocks.

Aristolochic acid I-induced apoptosis in LLC-PK1 cells and amelioration of the apoptotic damage by calcium antagonist

OBJECTIVE

To examine the effect of different concentrations of aristolochic acid I (AAI) in inducing apoptosis of cultured porcine renal cell line LLC-PK1 and to investigate the relationship between intracellular free calcium concentration ([Ca++]i) and LLC-PK1 apoptosis induced by AAI and the influence of a calcium antagonist, lacidipine on apoptosis and [Ca++]i.

METHODS

LLC-PK1 cells were treated in different groups: a. the normal group without treatment; b. the group with AAl alone (0.01 g.L-1, 0.02 g.L-1, 0.04 g.L-1, 0.08 g.L-1); c. the group with lacidipine alone (10 ng.L-1, 10(2) ng.L-1, 10(3) ng.L-1); d. the group with AAI (0.04 g.L-1) plus lacidipine (10 ng.L-1, 10(2) ng.L-1, 10(3) ng.L-1). Light microscopy, agarose gel electrophoresis, Annexin-V-Flous apoptosis detection kit and flow cytometry using propidium iodide staining to identify or quantify the apoptosis of LLC-PK1 cells. Mean [Ca++]i was measured by laser confocus microscopy using Fluo-3/AM staining.

RESULTS

A series of morphologic changes that were characteristic of apoptosis, Annexin-V-Flous staining positive apoptotic cells and "DNA ladder" were identified in AAI (0.02 g.L-1-0.08 g.L-1) treated LLC-PK1 cells. Quantitative analysis of apoptotic cells showed that the percentage of apoptotic cells in AAI (0.02 g.L-1, 0.04 g.L-1 or 0.08 g.L-1) group was significantly higher than that in normal group (5.3%, 48.5%, 78.7% vs 2.6%, P < 0.001). Mean [Ca++]i was significantly higher in cells treated with AAI (0.04 g.L-1) than that in normal cells (58.01 +/- 18.89 vs 22.66 +/- 4.78, P < 0.001). In group treated with AAI plus lacidipine (102 ng.L-1, 103 ng.L-1), mean [Ca++]i was significantly lower than that treated with AAI alone (35.47 +/- 12.85, 28.55 +/- 10.16 vs 58.01 +/- 18.89, P < 0.001). And the percentage of apoptotic cells in group treated with AAI plus lacidipine (10(2) ng.L-1, 10(3) ng.L-1) was also significantly lower than that treated with AAI alone (19.0%, 27.8% vs 34.7%, P < 0.001).

CONCLUSIONS

High concentrations of AAI may induce apoptosis of LLC-PK1 cells. The mean [Ca++]i in AAI-treated LLC-PK1 cells was increased significantly, suggesting that the increase of [Ca++]i may be related to apoptosis in LLC-PK1 cells. Lacidipine may decrease the raised mean [Ca++]i levels caused by AAI and the percentage of apoptotic cells, and lacidipine may ameliorate AAI-induced apoptotic damage by inhibiting the increase of [Ca++]i in LLC-PK1 cells.

Silencing of metallothionein-I gene in mouse lymphosarcoma cells by methylation

Metallothionein-I (MT-I) gene is silenced by methylation of CpG islands in mouse lymphosarcoma P1798 cells but not in the thymus, the cell type from which the tumor was derived. Bisulfite genomic sequencing revealed that all 21 CpG dinucleotides present within -216 bp to +1 bp with respect to transcription start site are methylated in the tumor cell line, but none is methylated in the thymus. The lymphosarcoma cells induced MT-I in response to heavy metals only after demethylation with 5-azacytidine (5-AsaC). The electrophoretic mobility shift assay using specific oligonucleotide probes showed that the key transcription factors regulating MT-I gene (e.g., MTF-1, Sp 1 and MLTF/USF) are active in P1798 cells. In vivo footprinting of the proximal promoter region showed that none of the metal regulatory elements (MREs) or MLTF/USF are occupied in response to heavy metals. Demethylation of the lymphosarcoma cells with 5-AzaC resulted in constitutive footprinting at MLTF/ARE, and zinc-inducible footprinting at MRE-c, MRE-d and MRE-e sites. Demethylation of just 10-20% of the CpG islands was sufficient to render the gene inducible by cadmium or zinc. The MT-I induction persisted in the cancer cells for several generations even after withdrawal of 5-AzaC from the culture medium.

Luteolytic effects of DL111-IT in pregnant rats

The present studies were conducted to evaluate the effects of DL111-IT [3-(2-ethyl phenyl)-5-(3-methoxy phenyl)-1H-1,2,4 triazol] on ovaries of pregnant rats. Pregnant rats were i.m. treated with DL111-IT 2.5 mg kg(-1) day(-1) or camellia oleum (vehicle control) 0.2 ml/day from day 6 of pregnancy for 1, 3 or 5 days. Blood and ovaries were collected 24 h after the last injection. Ovarian fresh weight and protein contents, activities of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) in ovaries, and cell apoptosis of corpus luteum (including hematoxylin-eosine stain, in situ 3'-end labeling and nucleosomal banding) were estimated. Compared with that in the control group, ovarian fresh weight declined 11% and 22% after DL111-IT-3 days and -5 days; protein content dropped 29% after 5-day administration. DL111-IT for 3 days provoked a marked decrease of serum progesterone, by 31% of the control; the activity of 3beta-HSD decreased 34.4% after i.m. DL111-IT for 5 days, while that of 20alpha-HSD increased dramatically after only one injection of DL111-IT (P < 0.01). Histological analysis and in situ 3'-end DNA labeling indicated that DL111-IT induced the pyknosis of cells and the formations of apoptotic bodies and intense oligonucleosomes in luteal cells of pregnant rats. The cell apoptosis induced by DL111-IT was further confirmed by evaluation of nucleosomal DNA fragmentation by agarose gel electrophoresis in cultured luteal cells exposed to DL111-IT for 24 h. In conclusion, all results, including shrunken luteal cells, decreased concentration of protein content and serum progesterone, changed activities of 3beta-HSD and 20alpha-HSD and formation of DNA fragments in luteal cells, showed the luteolytic effect of DL111-IT in pregnant rats.

[Changes of prostaglandins in kidney tissue in gentamicin-induced acute renal tubular injury in rats]

OBJECTIVE

To examine the relationship between epidermal growth factor (EGF) and prostaglandins (PGs) in recovery of acute tubular necrosis (ATN) induced by gentamicin in rats and the changes of renal tissue PGs with EGF treatment.

METHODS

Female wistar rats were divided into three groups; normal(NL, n = 7); GM-treated only (Group G, n = 20); GM 200 mg/kg, i.p. x 3 d; GM and EGF-treated (Group G + E, n = 19): EGF(20 micrograms) was given after last GM injection. [3H]thymidine incorporation rate (3HTdR) of renal tissue, serum creatinine concentration (Scr), renal levels of PGE2, 6-keto-PGF1 alpha, TXB2 were measured at day 1,4,8,12 after GM administration.

RESULTS

[3H]thymidine incorporation rate of renal tissue in group G + E was significantly higher than that in group G after toxic injury. The histological lesions of group G + E was less severe than that in group G. 6-keto-PGF1 alpha in group G + E was increased significantly than that in group G, and renal TXB2 in group G + E was lower than that in group G. PGE2 and 6-keto-PGF1 alpha in group G + E was positively correlated with 3HTdR, respectively.

CONCLUSIONS

(1) changes of renal prostaglandins may be related to the injury/proliferation of renal tubular epithelial cells in ATN. (2) Administration of exogenous EGF may enhance the release of PGE2 and 6-keto-PGF1 alpha of renal tissue and inhibit the synthesis of renal TXB2. The results indicate that effect of ameliorating recovery of renal tubular epithelial cells of EGF could be partly related to the changes of renal PGs.

Observation of curative effect on eosinophilic gastroenteritis by treatment with method of reinforcement of essence of the kidney

12 patients with eosinophilic gastroenteritis were treated with prescriptions and drugs based mainly on the method of reinforcement of essence of the kidney. Remarkable curative effect was achieved in 9 cases and eutherapeutic effect in 3, i.e., the cure rate was 100%. The efficacy began to appear in a minimum of 7 days and a maximum of 12 days. There was no recurrence over 1 to 3 years' follow-up observation.

[Comparison of the three methods for estimating the dry-weight of hemodialysis patients]

In order to find the best method for estimating the dry-weight of hemodialysis (HD) patients, we compared the three methods used, i.e. bioelectrical resistivity (rho), plasma cGMP (cGMP) and bromide (Br) methods. The results showed that the extracellular fluid volume per unit body mass (EFV/mass) determined with rho was negatively correlated with that determined with Br. (r = -0.7601 for normal controls and -0.5293 for HD patients, P < 0.05). However, plasma cGMP concentration was neither correlated with EFV/mass (r = 0.3724 for normal control and 0.2538 for HD patients, P > 0.05) nor with rho (r = 0.5210 for normal controls and 0.2106 for HD patients, P > 0.05). These results suggest that the bioelectrical resistivity dry-weight method is more accurate than cGMP method and moreover it is easier to perform than the NaBr method.