Piezoelectricity is a unique material property that allows one to convert mechanical energy into electrical one or vice versa. Transition metal dichalcogenides (TMDC) and transition metal dioxides ...(TMDO) are expected to have great potential for piezoelectric device applications due to their noncentrosymmetric and two-dimensional crystal structure. A detailed theoretical investigation of the piezoelectric stress (e 11) and piezoelectric strain (d 11) coefficients of single layer TMDCs and TMDOs with chemical formula MX2 (where M= Cr, Mo, W, Ti, Zr, Hf, Sn and X = O, S, Se, Te) is presented by using first-principles calculations based on density functional theory. We predict that not only the Mo- and W-based members of this family but also the other materials with M= Cr, Ti, Zr and Sn exhibit highly promising piezoelectric properties. CrTe2 has the largest e 11 and d 11 coefficients among the group VI elements (i.e., Cr, Mo, and W). In addition, the relaxed-ion e 11 and d 11 coefficients of SnS2 are almost the same as those of CrTe2. Furthermore, TiO2 and ZrO2 pose comparable or even larger e 11 coefficients as compared to Mo- and W-based TMDCs and TMDOs. Our calculations reveal that TMDC and TMDO structures are strong candidates for future atomically thin piezoelectric applications such as transducers, sensors, and energy harvesting devices due to their piezoelectric coefficients that are comparable (even larger) to currently used bulk piezoelectric materials.
A pathological complete remission (pCR) is rarely achieved by neoadjuvant chemotherapy in estrogen receptor-positive (ER+) HER2-negative (HER2−) tumors. Therefore, its use might be questionable in ...specific groups of this tumor type. To select which patients benefit and which could be spared neoadjuvant chemotherapy, we tested standard pathology and molecular markers in ER+ HER2− breast tumors. Pretreatment biopsies were available from 211 ER+ HER2− tumors, who had been treated with neoadjuvant chemotherapy (adriamycin/cyclophosphamide). mRNA expression data were available for 132 tumors. We determined progesterone receptor expression (PR), endocrine sensitivity, HER2 expression, histology, proliferation, and molecular subtypes. We correlated these data to chemotherapy response using pCR rates and the previously published neoadjuvant response index (NRI). PR-negative tumors (
n
= 65, 30.8%) and luminal B type tumors (
n
= 43, 20.4%) responded significantly better to chemotherapy than other tumors. These associations remained significant in multivariate analysis. However, even in the subgroup of patients with the lowest response rate, comprising tumors that had both a positive-PR expression and the luminal A subtype (
n
= 58, 44%), the majority of the patients had downstaging because of chemotherapy. For histology (lobular vs. ductal), endocrine sensitivity, and proliferation, no associations with chemotherapy response were observed. Gene expression array analysis resulted in 28 significant genes (FDR < 0.1). PR expression and luminal B status are associated with a better response to neoadjuvant chemotherapy. However, both markers had only weak response predictive power, and it was not possible to identify a subgroup with no or only minimal chemotherapy benefit. Therefore, the decision to refrain from neoadjuvant chemotherapy to ER+ HER2− breast tumors should not be based on predictive markers, but exclusively on estimates of prognosis.
Ab initio calculations within the density-functional theory formalism are performed to investigate the chemical functionalization of a graphene-like monolayer of silicon-silicene-with B, N, Al, or P ...atoms. The structural, electronic, magnetic, and vibrational properties are reported. The most preferable adsorption sites are found to be valley, bridge, valley and hill sites for B, N, Al, and P adatoms, respectively. All the relaxed systems with adsorbed/substituted atoms exhibit metallic behavior with strongly bonded B, N, Al, and P atoms accompanied by an appreciable electron transfer from silicene to the B, N, and P adatom/substituent. The Al atoms exhibit opposite charge transfer, with n-type doping of silicene and weaker bonding. The adatoms/substituents induce characteristic branches in the phonon spectrum of silicene, which can be probed by Raman measurements. Using molecular dynamics, we found that the systems under study are stable up to at least T = 500 K. Our results demonstrate that silicene has a very reactive and functionalizable surface.
The absence of a direct-to-indirect band gap transition in ReS2 when going from the monolayer to bulk makes it special among the other semiconducting transition metal dichalcogenides. The ...functionalization of this promising layered material emerges as a necessity for the next generation technological applications. Here, the structural, electronic, and magnetic properties of substitutionally doped ReS2 monolayers at either the S or Re site were systematically studied by using first principles density functional calculations. We found that substitutional doping of ReS2 depends sensitively on the growth conditions of ReS2. Among the large number of non-metallic atoms, namely H, B, C, Se, Te, F, Br, Cl, As, P, and N, we identified the most promising candidates for n-type and p-type doping of ReS2. While Cl is an ideal candidate for n-type doping, P appears to be the most promising candidate for p-type doping of the ReS2 monolayer. We also investigated the doping of ReS2 with metal atoms, namely Mo, W, Ti, V, Cr, Co, Fe, Mn, Ni, Cu, Nb, Zn, Ru, Os and Pt. Mo, Nb, Ti, and V atoms are found to be easily incorporated in a single layer of ReS2 as substitutional impurities at the Re site for all growth conditions considered in this work. Tuning chemical potentials of dopant atoms energetically makes it possible to dope ReS2 with Fe, Co, Cr, Mn, W, Ru, and Os at the Re site. We observe a robust trend for the magnetic moments when substituting a Re atom with metal atoms such that depending on the electronic configuration of dopant atoms, the net magnetic moment of the doped ReS2 becomes either 0 or 1 μB. Among the metallic dopants, Mo is the best candidate for p-type doping of ReS2 owing to its favorable energetics and promising electronic properties.
Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies
. Previous attempts to control water ...permeation through membranes (mainly polymeric ones) have concentrated on modulating the structure of the membrane and the physicochemical properties of its surface by varying the pH, temperature or ionic strength
. Electrical control over water transport is an attractive alternative; however, theory and simulations
have often yielded conflicting results, from freezing of water molecules to melting of ice
under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes
. Such membranes have previously been shown to exhibit ultrafast permeation of water
and molecular sieving properties
, with the potential for industrial-scale production. To achieve electrical control over water permeation, we create conductive filaments in the graphene oxide membranes via controllable electrical breakdown. The electric field that concentrates around these current-carrying filaments ionizes water molecules inside graphene capillaries within the graphene oxide membranes, which impedes water transport. We thus demonstrate precise control of water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for developing smart membrane technologies for artificial biological systems, tissue engineering and filtration.
Background
The treatment of axillary lymph node metastases after neoadjuvant systemic therapy (NST) remains debatable and axillary lymph node dissection (ALND) is still the standard of care. Marking ...axillary lymph nodes with radioactive iodine seeds (MARI procedure) is accurate in restaging the axilla after NST (false‐negative rate 7 per cent). Here, the potential of tailored axillary treatment, determined by combining the results of PET–CT before NST with those of the MARI procedure after NST, was analysed.
Methods
A cohort of axillary node‐positive patients was used to construct a hypothetical treatment algorithm based on a combination of PET–CT and the MARI procedure. In the algorithm, the number of fluorodeoxyglucose (FDG)‐avid axillary lymph nodes (1–3 versus 4 or more) before NST and the tumour status of the MARI node (positive versus negative) after NST were used to tailor axillary treatment. All patients in the cohort underwent ALND, allowing estimation of potential overtreatment and undertreatment.
Results
A total of 93 patients were included in the study. Between one and three FDG‐avid axillary lymph nodes were observed in 59 patients, and four or more in 34 patients. The MARI node was tumour‐negative in 32 patients and showed residual disease in 61. Treatment according to the constructed algorithm would have resulted in 74 per cent of patients avoiding an ALND, with potential undertreatment in three patients (3 per cent) and overtreatment in 16 (17 per cent).
Conclusion
Tailored axillary treatment after NST in node‐positive patients, by combining PET–CT before NST and the MARI procedure after NST, has the potential for ALND to be avoided in 74 per cent of patients.
Reduced axillary lymph node dissection rates
A superconducting diode is an electronic device that conducts supercurrent and exhibits zero resistance primarily for one direction of applied current. Such a dissipationless diode is a desirable ...unit for constructing electronic circuits with ultralow power consumption. However, realizing a superconducting diode is fundamentally and technologically challenging, as it usually requires a material structure without a centre of inversion, which is scarce among superconducting materials. Here, we demonstrate a superconducting diode achieved in a conventional superconducting film patterned with a conformal array of nanoscale holes, which breaks the spatial inversion symmetry. We showcase the superconducting diode effect through switchable and reversible rectification signals, which can be three orders of magnitude larger than that from a flux-quantum diode. The introduction of conformal potential landscapes for creating a superconducting diode is thereby proven as a convenient, tunable, yet vastly advantageous tool for superconducting electronics. This could be readily applicable to any superconducting materials, including cuprates and iron-based superconductors that have higher transition temperatures and are desirable in device applications.
Purpose
Breast-contour preservation (BCP) is possible for most women treated for early-stage breast cancer. BCP can be defined as primary breast-conserving treatment (BCT), neoadjuvant chemotherapy ...(NAC) followed by BCT and immediate postmastectomy breast reconstruction (IBR). This study provides insight in current BCP strategies in Denmark and the Netherlands and aims to identify opportunities for improvement within both countries.
Methods
A total of 92,881 patients with early-stage breast cancer who were operated in Denmark and the Netherlands between 2012 and 2017 were selected from the Danish Breast Cancer Group and the Dutch National Breast Cancer Audit databases. BCP procedures and predictive factors were analyzed within and between both countries.
Results
BCP was achieved in 76.7% (
n
= 16,355) of the Danish and in 74.5% (
n
= 53,328) of the Dutch patients. While BCP rate did not change significantly over time in Denmark (
p
= 0.250), a significant increase in BCP rate from 69.5% in 2012 to 78.5% in 2017 (
p
< 0.001) was observed in the Netherlands. In both countries, variation in BCP rates between hospitals decreased over time. NAC followed by BCT and postmastectomy IBR was substantially more often used in the Netherlands compared to Denmark, specifically in patients younger than 50 years.
Conclusions
In more than 75% of all Danish and Dutch patients, surgically treated for early-stage breast cancer, the breast-contour was preserved. The different use of BCP strategies within Denmark and the Netherlands and the differences observed between hospitals in both countries emphasize the need for more (inter)national consensus on treatment modalities.
The concept of nonlinear normal modes (NNMs) is discussed in the present paper and its companion, Part II. Because there is virtually no application of the NNMs to large-scale engineering structures, ...these papers are an attempt to highlight several aspects that might drive their development in the future. Specifically, we support that (i) numerical methods for the continuation of periodic solutions pave the way for an effective and practical computation of NNMs, and (ii) time–frequency analysis is particularly suitable for the analysis of the resulting dynamics. Another objective of the present paper is to describe, in simple terms, and to illustrate the fundamental properties of NNMs. This is achieved to convince the structural dynamicist not necessarily acquainted with them that they are a useful framework for the analysis of nonlinear vibrating structures.
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