Understanding resonant charge transport through weakly coupled single-molecule junctions

Off-resonant charge transport through molecular junctions has been extensively studied since the advent of single-molecule electronics and it is now well understood within the framework of the non-interacting Landauer approach. Conversely, gaining a qualitative and quantitative understanding of the resonant transport regime has proven more elusive. Here, we study resonant charge transport through graphene-based zinc-porphyrin junctions. We experimentally demonstrate an inadequacy of the non-interacting Landauer theory as well as the conventional single-mode Franck-Condon model. Instead, we model the overall charge transport as a sequence of non-adiabatic electron transfers, the rates of which depend on both outer and inner-sphere vibrational interactions. We show that the transport properties of our molecular junctions are determined by a combination of electron-electron and electron-vibrational coupling, and are sensitive to the interactions with the wider local environment. Furthermore, we assess the importance of nuclear tunnelling and examine the suitability of semi-classical Marcus theory as a description of charge transport in molecular devices.Comment: version accepted in Nature Communications; SI available at https://researchportal.hw.ac.uk/en/publications/understanding-resonant-charge-transport-through-weakly-coupled-s

Marked isotopic variability within and between the Amazon River and marine dissolved black carbon pools

Riverine dissolved organic carbon (DOC) contains charcoal byproducts, termed black carbon (BC). To determine the significance of BC as a sink of atmospheric CO2 and reconcile budgets, the sources and fate of this large, slow-cycling and elusive carbon pool must be constrained. The Amazon River is a significant part of global BC cycling because it exports an order of magnitude more DOC, and thus dissolved BC (DBC), than any other river. We report spatially resolved DBC quantity and radiocarbon (Δ14C) measurements, paired with molecular-level characterization of dissolved organic matter from the Amazon River and tributaries during low discharge. The proportion of BC-like polycyclic aromatic structures decreases downstream, but marked spatial variability in abundance and Δ14C values of DBC molecular markers imply dynamic sources and cycling in a manner that is incongruent with bulk DOC. We estimate a flux from the Amazon River of 1.9–2.7 Tg DBC yr−1 that is composed of predominately young DBC, suggesting that loss processes of modern DBC are important

Current practice and surgical outcomes of neoadjuvant chemotherapy for early breast cancer : UK NeST study

Funding Information: This work was funded by a grant from the Association of Breast SurgeryPeer reviewedPublisher PD

Understanding resonant charge transport through weakly coupled single-molecule junctions

Off-resonant charge transport through molecular junctions has been extensively studied since the advent of single-molecule electronics and it is now well understood within the framework of the non-interacting Landauer approach. Conversely, gaining a qualitative and quantitative understanding of the resonant transport regime has proven more elusive. Here, we study resonant charge transport through graphene-based zinc-porphyrin junctions. We experimentally demonstrate an inadequacy of the non-interacting Landauer theory as well as the conventional single-mode Franck-Condon model. Instead, we model the overall charge transport as a sequence of non-adiabatic electron transfers, the rates of which depend on both outer and inner-sphere vibrational interactions. We show that the transport properties of our molecular junctions are determined by a combination of electron-electron and electron-vibrational coupling, and are sensitive to the interactions with the wider local environment. Furthermore, we assess the importance of nuclear tunnelling and examine the suitability of semi-classical Marcus theory as a description of charge transport in molecular devices.Comment: version accepted in Nature Communications; SI available at https://researchportal.hw.ac.uk/en/publications/understanding-resonant-charge-transport-through-weakly-coupled-s

Investigation of the band alignment at the interface between 2D/3D halide perovskite films and charge extraction layers

International audienc

Investigation of the band alignment at the interface between 2D/3D halide perovskite films and charge extraction layers

International audienc

Effect of neoadjuvant chemotherapy on breast cancer phenotype, ER/PR and HER2 expression - Implications for the practising oncologist

Purpose To assess the effect of neoadjuvant chemotherapy (NACT) on breast cancer characteristics, hormone receptors and human epidermal growth factor receptor 2 (HER2) expression and whether testing should be repeated on residual tumours. Material and methods Patients with primary operable breast cancer who received NACT at a single United Kingdom tertiary referral centre were included. Tumour type, grade (including details of mitotic grade, tubule formation and pleomorphism), oestrogen receptor (ER), progesterone receptor (PR) and HER2 status were compared between pre-treatment and post-treatment residual samples using tissue microarrays. A control group of paired core and excision tumours from patients who did not receive NACT was also assessed. Results Two hundred forty-six cases and 113 controls were included. Pathological complete response (path CR) was achieved in 21.5% of patients. In those patients failing to achieve a path CR, a change in the histological type was noted in 29 out of 178 cases (16.3%, p < 0.001) with increase in the lobular and metaplastic types. Downgrading occurred in 28.8%, due to significant reduction in mitotic rate and prominent tubule formation. A change in ER/PR/HER2 status occurred in 12%, 14.5% and 7.1% of cases, respectively, predominantly as a switch from negative to positive status for ER and from positive to negative status for HER2. Further alterations in expression levels were also noted. Minimal changes in the low ER/PR expressors and the HER2 2+ tumours were found in the control group. Conclusion Significant changes in tumour morphology, grade, hormone receptors and HER2 status occur following NACT. We recommend testing on residual invasive carcinoma. A switch from negative to positive status warrants offering endocrine/trastuzumab-based therapy to this group of patients

Serial MRI scans help in assessing early response to neoadjuvant chemotherapy and tailoring breast cancer treatment

Background Tailoring neoadjuvant chemotherapy (NAC) during breast cancer treatment is performed to improve overall tumour response, with increasing evidence to support its role. This study evaluates our breast unit's experience in MRI assessment of tumour response as an aid in tailoring NAC. Materials and methods This is a retrospective study of patients treated with NAC for breast cancer between 2005 and 2009 who underwent MRI to assess tumour response. Response to NAC was monitored before NAC and after 2 and/or 4 cycles of anthracycline and cyclophosphamide (AC) chemotherapy. Taxane was substituted for AC if MRI response was deemed inadequate. Tumour response on last MRI was correlated with final pathology against different tumour subtypes and in inflammatory tumours. Strength of agreement was measured using Kappa analysis. Potential predictive factors for MRI response were assessed for significance. Results 166 tumours were assessed with serial MRI scans. MRI showed high sensitivity rate (93.1%) in predicting response to NAC particularly for tumours showing partial (PR) or complete (CR) response on pathology (p < 0.001) with fair agreement on Kappa analysis (K = 0.31). MRI seems more accurate in triple negative, HR+/HER2+ and high-grade tumours. Early identification of non-responders on MRI resulted in early tailoring of NAC, with improved rates of tumour response seen in 74.2% following switching NAC. Logistic regression showed that PR or CR observed on MRI after 2 NAC cycles significantly predicted pCR (p < 0.001). Conclusion Serial MRI can be used to assess patterns of tumour response to NAC. This study shows that tailoring NAC according to pattern of response can improve overall tumour response rates

Configuring electronic states in an atomically precise array of quantum boxes

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOA 2D array of electronically coupled quantum boxes is fabricated by means of on‐surface self‐assembly assuring ultimate precision of each box. The quantum states embedded in the boxes are configured by adsorbates, whose occupancy is controlled with atomic precision. The electronic interbox coupling can be maintained or significantly reduced by proper arrangement of empty and filled boxes.122837573763FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2013/04855-0The authors would like to acknowledge financial support from the Swiss Nanoscience Institute (SNI), Swiss National Science Foundation (Grants Nos. 200020‐149713 and 206021‐121461), the Spanish Ministry of Economy (Grant No. MAT2013‐46593‐C6‐4‐P), the Basque Government (Grant No. IT621‐13), the São Paulo Research Foundation (Grant No. 2013/04855‐0), Swiss Government Excellence Scholarship Program, Netherlands Organization for Scientific Research NWO (Chemical Sciences, VIDI‐Grant No. 700.10.424), the European Research Council (ERC‐2012‐StG 307760‐SURFPRO), University of Basel, University of Heidelberg, Linköping University, University of Groningen, Paul Scherrer Institute, and the Japan Science and Technology Agency (JST) “Precursory Research for Embryonic Science and Technology (PRESTO)” for a project of “Molecular technology and creation of new function.” The authors sincerely thank Marco Martina and Rémy Pawlak for support during the measurements

Neoadjuvant Chemotherapy Induces Expression Levels of Breast Cancer Resistance Protein That Predict Disease-Free Survival in Breast Cancer

<div><p>Three main xenobiotic efflux pumps have been implicated in modulating breast cancer chemotherapy responses. These are P-glycoprotein (Pgp), Multidrug Resistance-associated Protein 1 (MRP1), and Breast Cancer Resistance Protein (BCRP). We investigated expression of these proteins in breast cancers before and after neoadjuvant chemotherapy (NAC) to determine whether their levels define response to NAC or subsequent survival. Formalin-fixed paraffin-embedded tissues were collected representing matched pairs of core biopsy (pre-NAC) and surgical specimen (post-NAC) from 45 patients with invasive ductal carcinomas. NAC regimes were anthracyclines +/− taxanes. Immunohistochemistry was performed for Pgp, MRP1 and BCRP and expression was quantified objectively using computer-aided scoring. Pgp and MRP1 were significantly up-regulated after exposure to NAC (Wilcoxon signed-rank p = 0.0024 and p<0.0001), while BCRP showed more variation in response to NAC, with frequent up- (59% of cases) and down-regulation (41%) contributing to a lack of significant difference overall. Pre-NAC expression of all markers, and post-NAC expression of Pgp and MRP1 did not correlate with NAC response or with disease-free survival (DFS). Post-NAC expression of BCRP did not correlate with NAC response, but correlated significantly with DFS (Log rank p = 0.007), with longer DFS in patients with low post-NAC BCRP expression. In multivariate Cox regression analyses, post-NAC BCRP expression levels proved to predict DFS independently of standard prognostic factors, with high expression associated with a hazard ratio of 4.04 (95% confidence interval 1.3–12.2; p = 0.013). We conclude that NAC-induced expression levels of BCRP predict survival after NAC for breast cancer, while Pgp and MRP1 expression have little predictive value.</p></div