The photovoltaic effect in traditional p-n junctions-where a p-type material (with an excess of holes) abuts an n-type material (with an excess of electrons)-involves the light-induced creation of ...electron-hole pairs and their subsequent separation, generating a current. This photovoltaic effect is particularly important for environmentally benign energy harvesting, and its efficiency has been increased dramatically, almost reaching the theoretical limit
. Further progress is anticipated by making use of the bulk photovoltaic effect (BPVE)
, which does not require a junction and occurs only in crystals with broken inversion symmetry
. However, the practical implementation of the BPVE is hampered by its low efficiency in existing materials
. Semiconductors with reduced dimensionality
or a smaller bandgap
have been suggested to be more efficient. Transition-metal dichalcogenides (TMDs) are exemplary small-bandgap, two-dimensional semiconductors
in which various effects have been observed by breaking the inversion symmetry inherent in their bulk crystals
, but the BPVE has not been investigated. Here we report the discovery of the BPVE in devices based on tungsten disulfide, a member of the TMD family. We find that systematically reducing the crystal symmetry beyond mere broken inversion symmetry-moving from a two-dimensional monolayer to a nanotube with polar properties-greatly enhances the BPVE. The photocurrent density thus generated is orders of magnitude larger than that of other BPVE materials. Our findings highlight not only the potential of TMD-based nanomaterials, but also more generally the importance of crystal symmetry reduction in enhancing the efficiency of converting solar to electric power.
Background
Primary tumour location is emerging as an important prognostic factor in localized and metastatic colorectal cancers. However, its prognostic role in colorectal liver metastasis (CRLM) ...after hepatectomy remains controversial. A systematic review and meta‐analysis was undertaken to evaluate its prognostic value.
Methods
References were identified through searches of PubMed, Embase, Web of Science and the Cochrane Library comparing overall or disease‐free survival after hepatic resection between patients with CRLM originating from right‐ or left‐sided colorectal cancers. Data were pooled using hazard ratios (HRs) and 95 per cent confidence intervals according to a random‐effects model. Meta‐regression and subgroup analyses were conducted to assess the effect of underlying confounding factors on HR estimates and to adjust for this.
Results
The final analysis included 21 953 patients from 45 study cohorts. Compared with left‐sided primary tumour location, right‐sided location was associated with worse overall survival (HR 1·39, 95 per cent c.i. 1·28 to 1·51; P < 0·001; prediction interval 1·00 to 1·93), and also tended to have a negative impact on disease‐free survival (HR 1·18, 1·06 to 1·32; P = 0·004; prediction interval 0·79 to 1·75). Subgroup analysis showed that the negative effect of right‐sided primary tumour location on overall survival was more prominent in the non‐Asian population (HR 1·47, 1·33 to 1·62) than the Asian population (HR 1·18, 1·05 to 1·32) (P for interaction <0·01).
Conclusion
This study demonstrated a prognostic role for primary tumour location in patients with CRLM receiving hepatectomy, especially regarding overall survival. Adding primary tumour location may provide important optimization of prognosis prediction models for CRLM in current use.
Antecedentes
La ubicación del tumor primario (primary tumor location, PTL) ha surgido como un factor pronóstico importante en los cánceres colorrectales (colorectal cancers, CRCs) localizados y metastásicos. Sin embargo, todavía se discute su relevancia como factor pronóstico tras la resección de metástasis hepáticas de cáncer colorrectal (colorectal liver metastases, CRLM). Se realizó una revisión sistemática y un metaanálisis para determinar su valor pronóstico.
Métodos
En PubMed, EMBASE, Web of Science y la Biblioteca Cochrane se identificaron los trabajos que compararon la supervivencia global (overall survival, OS) y la supervivencia libre de enfermedad (disease‐free survival, DFS) tras la resección hepática de CRLM cuyo CRCs estuviese situado en el lado derecho o izquierdo. Los datos se expresaron en forma del cociente de riesgos instantáneos (hazard ratio, HR) e intervalos de confianza del 95% (i.c. del 95%) de acuerdo con un modelo de efectos aleatorios. Se efectuaron análisis de metarregresión y de subgrupos para evaluar el efecto de los factors de confusión existentes en las estimaciones de HR, ajustando por los mismos.
Resultados
El análisis final incluyó 21.953 pacientes de cohortes de 45 estudios. La PTL en el lado derecho en comparación con el lado izquierdo se asoció con una peor supervivencia global (HR 1,39; i.c. del 95% 1,28‐1,51; P < 0,001; intervalo de predicción 1,00‐1,93) y una tendencia a un impacto negativo en la DFS (HR 1,18; i.c. del 95% 1,06‐1,32; P = 0,004; intervalo de predicción 0,79‐1,75). El análisis de subgrupos mostró que el efecto negativo de la PTL del lado derecho en la OS fue más prominente en la población no asiática (HR 1,47; i.c. del 95% 1,33‐1,62) que en la asiática (HR 1,18; i.c. del 95% 1,05‐1,32; Pinteracción < 0,01).
Conclusión
Este estudio demostró que la PTL tiene un papel pronóstico tras la hepatectomía de las CRLM, especialmente respecto a la OS. La adición de la PTL proporcionaría una optimización importante en los modelos actuales de predicción pronóstica de CRLM.
The prognostic role of primary tumour location in colorectal liver metastases (CRLM) after hepatectomy remains controversial. This meta‐analysis demonstrated a prognostic role of primary tumour location in CRLM receiving hepatectomy, especially regarding overall survival.
Primary tumor location has prognostic value
Magnetotail reconnection plays a crucial role in explosive energy conversion in geospace. Because of the lack of in-situ spacecraft observations, the onset mechanism of magnetotail reconnection, ...however, has been controversial for decades. The key question is whether magnetotail reconnection is externally driven to occur first on electron scales or spontaneously arising from an unstable configuration on ion scales. Here, we show, using spacecraft observations and particle-in-cell (PIC) simulations, that magnetotail reconnection starts from electron reconnection in the presence of a strong external driver. Our PIC simulations show that this electron reconnection then develops into ion reconnection. These results provide direct evidence for magnetotail reconnection onset caused by electron kinetics with a strong external driver.
The enhancement of thermoelectric performance should be a compromise of electrical as well as thermal transports with reasonably little reduction of thermopower. In this study, the effects of ...co-doping by rare earth Pr and alkaline earth Sr on perovskite Ca0.92-xPr0.08SrxMnO3 (x = 0, 0.01, 0.02, 0.03, 0.04) bulk materials are evaluated in terms of the phase composition, microstructure, grain combination, electrical transport as well as the thermal transport properties. The results show that perovskite type phases are reserved for the doped bulk materials. The bulk Material porosity can be decreased obviously and better grain interconnection is formed by introducing co-doping. The electrical conductivity is enhanced due to increased carrier concentration and mobility. The carriers for the intrinsic CaMnO3 and the co-doped Ca0.92-xPr0.08SrxMnO3 (x = 0, 0.01, 0.02, 0.03, 0.04) bulk materials follow the adiabatic polaron transport model; the activation energy as well as the band gap are reduced. The total thermal conductivity is further reduced by co-doping of Sr comparing with the Pr single-doped bulk materials. The co-doping is effective for further confining the thermal conduction. The ZT values of the co-doped samples are increased by 12.5%, 18.7%, 25% and 18.7% comparing with the Pr single-doped materials, respectively.
The enhancement of thermoelectric performance should be a compromising of balancing electrical transport as well as the thermal transports with reasonably little reduction of thermopower. In this study, the A site co-doped CaMnO3 bulk materials are evaluated as to the phase composition, microstructure, grain combination, electrical transport as well as the thermal transport properties. The bulk material porosity is decreased obviously. The electrical conductivity is enhanced due to the increased carrier concentration and mobility. The carriers follow the adiabatic polaron transport model. The total thermal conductivity can be further reduced by co-doping. The largest ZT value of the co-doped samples is increased by 25% comparing with the Pr single-doped materials. The co-doping using rare earth element and alkaline earth element is alternatively effective for further improve thermoelectric performance of the titled CaMnO3 bulk materials. Display omitted
•The bulk material porosity is decreased obviously by introducing co-doping.•The electrical conductivity is enhanced due to the increased carrier concentration and mobility.•The carriers for the bulk materials follow the adiabatic polaron transport model.•The ZT of the co-doped materials are increased remarkably comparing with the Pr single-doped materials.
Dysregulated expression of microRNAs (miRNAs) is associated with a variety of diseases, including colorectal cancer. By comparing more than 200 miRNAs in 13 pairs of matched colorectal cancer and ...normal adjacent tissue samples through qRT-PCR and microarray analysis, we found a widespread disruption of miRNA expression during colorectal tumorigenesis. In particular, among a panel of presumed targets generated by in silico analysis that may interact with these aberrantly expressed miRNAs, KRAS oncogene has been further experimentally validated as the target of miR-143. First, an inverse correlation between KRAS protein and miR-143 in vivo was found. Second, KRAS expression in Lovo cells was significantly abolished by treatment with miR-143 mimic, whereas miR-143 inhibitor increased KRAS protein level. Third, luciferase reporter assay confirmed that miR-143 directly recognize the 3'-untranslated region of KRAS transcripts. Four, Lovo cells treated with miR-143 inhibitor showed a stimulated cell proliferation, whereas miR-143 overexpression had an opposite effect. Finally, inhibition of KRAS expression by miR-143 inhibits constitutive phosphorylation of ERK1/2. Taken together, the present study provides the first evidences that miR-143 is significant in suppressing colorectal cancer cell growth through inhibition of KRAS translation.
Aberrant activation of the Wnt/β-catenin pathway is frequent in hepatocellular carcinoma (HCC) and contributes to HCC initiation and progression. This abnormal activation may result from somatic ...mutations in the genes of the Wnt/β-catenin pathway and/or dysregulation of the Wnt/β-catenin pathway. The mechanism for the latter remains poorly understood. Prospero-related homeobox 1 (PROX1) is a downstream target of the Wnt/β-catenin pathway in human colorectal cancer and elevated PROX1 expression promotes malignant progression. However, the Wnt/β-catenin pathway does not regulate PROX1 expression in the liver and HCC cells. Here we report that PROX1 promotes HCC cell proliferation in vitro and tumor growth in HCC xenograft mice. PROX1 and β-catenin levels are positively correlated in tumor tissues as well as in cultured HCC cells. PROX1 can upregulate β-catenin transcription by stimulating the β-catenin promoter and enhance the nuclear translocation of β-catenin in HCC cells, which leads to the activation of the Wnt/β-catenin pathway. Moreover, we show that increase in PROX1 expression renders HCC cells more resistant to sorafenib treatment, which is the standard therapy for advanced HCC. Overall, we have pinpointed PROX1 as a critical factor activating the Wnt/β-catenin pathway in HCC, which promotes HCC proliferation and sorafenib resistance.
•Demonstration of importance of the VVUQ in BEPU methodology development.•Review of the applicable technical standards and procedures on VVUQ for BEPU methodology development.•Review of the ...regulatory requirements and recommendations on VVUQ for BEPU methodology development.•Review of examples of industrial applications and good practices on VVUQ for BEPU methodology development.
In the process of a best estimate plus uncertainty (BEPU) methodology implementation for nuclear power plant safety analyses, the verification and validation (V&V) process including the uncertainty quantification (UQ) of the used computer codes and plant models plays an essential role. From the technical point of view, a BEPU methodology must be based on fully verified and validated codes and models, with quantified key model uncertainties. From the regulatory point of view, the adequacy of the simulation codes and plant models for the intended BEPU application must be assessed through the VVUQ process. These high level requirements of VVUQ result in high-cost for BEPU methodology development, preventing wider applications. Pragmatic, graded applications and practices of VVUQ in the BEPU methodology development are needed to allow to take full benefit of BEPU applications.
Using the ten-year (2000–2009) Data-Assimilation (DA) quality Terra MODIS and MISR aerosol products, as well as 7 years of Aqua MODIS, we studied both regional and global aerosol trends over oceans. ...This included both operational and data assimilation grade versions of the products. After correcting for what appears to be aerosol signal drift from the radiometric calibration of both MODIS instruments, we found MODIS and MISR agreed on a statistically negligible global trend of ±0.003/per decade. Our study also suggests that AODs over the Indian Bay of Bengal, east coast of Asia, and Arabian Sea show increasing trends of 0.07, 0.06, and 0.06 per decade for MODIS, respectively. These regional trends are considered as significant with a confidence level above 95%. Similar increasing trends were found from MISR, but with less relative magnitude. These trends reflect respective increases in the optical intensity of aerosol events in each region: anthropogenic aerosols over the east coast of China and Indian Bay of Bengal; and a stronger influence from dust events over the Arabian Sea. Negative AOD trends, low in confidence levels, are found off Central America, the east coast of North America, and the west coast of Africa, which indicate that longer periods of observation are necessary to be conclusive.
BNIP3 and NIX are proteins related to the BH3-only family, which induce both cell death and autophagy. Consistent with their ability to induce cell death, BNIP3 and NIX are implicated in the ...pathogenesis of cancer and heart disease. In tumor cells, BNIP3 and NIX are regulated by hypoxia, and the deregulation of BNIP3 or NIX expression is associated with tumor growth. In heart muscle, BNIP3 and NIX are regulated by hypoxia and Galphaq-dependent signaling, respectively, and their expression is associated with decreased myocardial function. Apart from their role in cell death, BNIP3 and NIX are also implicated in the induction of autophagy. In erythroid cells, NIX is required for a specialized type of autophagy that targets mitochondria for elimination (mitophagy). Similarly, BNIP3 regulates mitophagy in response to hypoxia. In this review, we will discuss possible mechanisms by which BNIP3 and NIX induce cell death and mitophagy. We will also consider the potential relationship between cell death pathways and autophagy in development and homeostasis.
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