We have studied hybrid solar cells based on the polymer poly(3-hexylthiophene) (P3HT) and colloidal CdSe nanocrystals. Using CdSe nanospheres with varying size, we have found that the power ...conversion efficiency (
η
P
) of these devices increases monotonically with the CdSe nanocrystal size, from
η
P
=(0.39±0.04)% under AM1.5G solar illumination for 4.0±0.2
nm size nanospheres to
η
P
=(1.9±0.2)% for 6.8±0.5
nm size nanospheres. The efficiency increase with nanocrystal size is mostly due to a significant increase in the short-circuit current, whereas the open-circuit voltage and fill factor of the solar cells are less affected. The devices also exhibit abnormal initial aging behavior when exposed to air, as an increase in both the short-circuit current and open-circuit voltage during the first 30
min leads to a significant increase in
η
P
.
Nonthermal plasmas allow the preparation of ligand‐free quantum dots combining high production rates with superior crystalline quality and luminescence properties. Here, ZnO quantum dots are produced ...in a radiofrequency capacitively‐coupled plasma, exhibiting size dependent photoluminescent quantum yields up to 60% after air exposure—the highest reported to date for any compound semiconductor quantum dots prepared in the gas phase. Systematic studies indicate the importance of the surface for the observed luminescence behavior. The high luminescent quantum yields in the visible range of the spectrum and the ligand‐free, scalable synthesis make these quantum dots good candidates for light emitting applications.
ZnO quantum dots are prepared in a nonthermal plasma reactor operated with a high frequency source. Quantum dots with diameters down to 2.1 nm are achieved, exhibiting exceptional high quantum yields up to 60%. The mechanism for the dominating green–yellow emission is discussed and the influence of oxygen species on the emission spectrum is investigated.
Lithium is of great importance for green energy technology, and most industrial Li is sourced from brine lakes and pegmatites. Recently, strong Li enrichment has been reported in the late Palaeozoic ...Jiujialu Formation (C1jj) in Guizhou, South China; however, the source and the sedimentary processes that formed the Jiujialu Formation remain unclear. We present the U–Pb ages and trace element compositions of detrital zircon grains from the Jiujialu Formation and underlying dolomite of the Loushanguan Group (Cam2–3ls), which indicate the grains in the Jiujialu Formation on the margin of the Central Guizhou Uplift and in a depression in southeast Guizhou have three primary age peaks (1000–900, ∼760, and ∼530 Ma). These ages are similar to those of Ordovician strata, indicating a contribution from the Ordovician strata to the Jiujialu Formation in these areas. Detrital zircon grains from the Jiujialu Formation in the core of the Central Guizhou Uplift and the Loushanguan Group have two primary age peaks at ∼760 and ∼530 Ma, which suggests that the underlying Loushanguan Group supplied most of the material to the Jiujialu Formation in this area. The age distribution of detrital zircon grains indicates that sediment erosion from the sedimentary stratal transport was limited, and deposition occurred near the direct source. In addition, the trace element compositions of the detrital zircon grains indicate that their original source was magmatic rocks of the South China Block. An early Palaeozoic intracontinental orogeny in South China uplifted subduction-related magmatic rocks (1000–900 Ma) in the northeast of the South China Block, exposing them to weathering and providing material for the Ordovician strata. This suggests that the weathering of sedimentary strata can form clay-type Li deposits in areas with carbonate bedrock, and that the provenance of Cambrian–Ordovician sedimentary strata in the Yangtze Block was controlled by an early Palaeozoic intracontinental orogeny.
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•Detrital zircons from the Loushanguan Group dolomites were studied.•Magmatic rocks around the South China Block are original material source.•Cambrian and Ordovician strata are the provenances of the Jiujialu Formation.•Early Palaeozoic intracontinental orogeny effect on sedimentary strata in Yangtze Block
Molecular markers play an important role in predicting clinical outcomes in pancreatic adenocarcinoma (PAAD) patients. Analysis of the ferroptosis-related genes may provide novel potential targets ...for the prognosis and treatment of PAAD.
RNA-sequence and clinical data of PAAD was downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) public databases. The PAAD samples were clustered by a non-negative matrix factorization (NMF) algorithm. The differentially expressed genes (DEGs) between different subtypes were used by "limma_3.42.2" package. The R software package clusterProfiler was used for functional enrichment analysis. Then, a multivariate Cox proportional and LASSO regression were used to develop a ferroptosis-related gene signature for pancreatic adenocarcinoma. A nomogram and corrected curves were constructed. Finally, the expression and function of these signature genes were explored by qRT-PCR, immunohistochemistry (IHC) and proliferation, migration and invasion assays.
The 173 samples were divided into 3 categories (C1, C2, and C3) and a 3-gene signature model (ALOX5, ALOX12, and CISD1) was constructed. The prognostic model showed good independent prognostic ability in PAAD. In the GSE62452 external validation set, the molecular model also showed good risk prediction. KM-curve analysis showed that there were significant differences between the high and low-risk groups, samples with a high-risk score had a worse prognosis. The predictive efficiency of the 3-gene signature-based nomogram was significantly better than that of traditional clinical features. For comparison with other models, that our model, with a reasonable number of genes, yields a more effective result. The results obtained with qPCR and IHC assays showed that ALOX5 was highly expressed, whether ALOX12 and CISD1 were expressed at low levels in tissue samples. Finally, function assays results suggested that ALOX5 may be an oncogene and ALOX12 and CISD1 may be tumor suppressor genes.
We present a novel prognostic molecular model for PAAD based on ferroptosis-related genes, which serves as a potentially effective tool for prognostic differentiation in pancreatic cancer patients.
This paper is devoted to study the limit cycle bifurcations of a pendulum equation x˙=y,y˙=−sinx under non-smooth perturbations of polynomials of cosx, sinx and y of degree n with switching lines x=0 ...and y=0. The upper bounds of the number of limit cycles in both the oscillatory and the rotary regions are obtained by expressing the corresponding first order Melnikov functions as several generating functions, some of which are complete elliptic integrals of the first and second kind.
This paper deals with the problem of limit cycle bifurcations for a piecewise near-Hamilton system with four regions separated by algebraic curves y=±x2. By analyzing the obtained first order ...Melnikov function, we give an upper bound of the number of limit cycles which bifurcate from the period annulus around the origin under nth degree polynomial perturbations. In the case n=1, we obtain that at least 4 (resp. 3) limit cycles can bifurcate from the period annulus if the switching curves are y=±x2 (resp. y=x2 or y=−x2). The results also show that the number of switching curves affects the number of limit cycles.
Systems composed of piecewise smooth differential (PSD) mappings have quantitatively been searched for answers to a substantial issue of limit cycle (LC) bifurcations. In this paper, LC numbers ...(LCNs) of a PSD system (PSDS) consisting of four regions are dealt with. A Melnikov mapping whose order is one is implicitly obtained by finding its originators when the system is perturbed under any nth degree of real polynomials. Then, the approach employing the Picard–Fuchs mapping is utilized to attain a higher boundary of bifurcation LCNs of systems composed of PSD functions with a global center. The method we used could be implemented to examine the problems related to the LC of other PSDS.
A lack of consensus persists regarding the origin of photoluminescence in silicon nanocrystals. Here we report pressure-dependences of X-ray diffraction and photoluminescence from alkane-terminated ...colloidal particles. We determine the diamond-phase bulk modulus, observe multiple phase transitions, and importantly find a systematic photoluminescence red shift that matches the X conduction-to-Γvalence transition of bulk crystalline silicon. These results, reinforced by calculations, suggest that the efficient photoluminescence, frequently attributed to defects, arises instead from core-states that remain highly indirect despite quantum confinement.
Plasma‐synthesized silicon nanocrystals with alkene ligands have shown the potential to exhibit high‐efficiency photoluminescence, but results reported in the literature have been inconsistent. Here, ...for the first time, the role of the immediate post‐synthesis “afterglow plasma” environment is explored. The significant impact of gas injection into the afterglow plasma on the photoluminescence efficiency of silicon nanocrystals is reprorted. Depending on the afterglow conditions, photoluminescence quantum yields of silicon nanocrystals synthesized under otherwise identical conditions can vary by a factor of almost five. It is demonstrated that achieving a fast quenching of the particle temperature and a high flux of atomic hydrogen to the nanocrystal surface are essential for a high photoluminescence quantum yield of the produced silicon nanocrystals.
Plasma‐synthesized silicon nanocrystals with alkyl functionalization exhibit highly efficient photoluminescence depending on the immediate post‐synthesis “afterglow plasma” environment. Secondary hydrogen injection into the afterglow allows for fast quenching of the particle temperature and provides a high flux of atomic hydrogen to the nanocrystal surface, two features which are essential for producing efficient optical emission from silicon nanocrystals.
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