Photoelectrical Response in Single‐Layer Graphene Transistors

The illumination of single‐layer graphene (SLG) transistors with visible light causes a negative shift in their transfer curves, attributable to the desorption of oxygen. However, their hysteresis is not affected by illumination, which suggests that charge traps are not affected by the visible‐light exposure. When SLG transistors are covered with a layer of photoactive polymer, the photodesorption‐induced current change in the transistors becomes less significant than the effects caused by the surrounding photoactive polymer. These observations demonstrate that the photoelectrical response of SLG transistors is dominated by extrinsic mechanisms rather than by the direct photocurrent process. The results suggest a new strategy for achieving light detection. The large cross section of SLG films for receiving photons and the capability of tailoring photoelectrical properties on them is potentially useful for optoelectronic applications.     

Self‐Aligned and Scalable Growth of Monolayer WSe2–MoS2 Lateral Heterojunctions

2D layered heterostructures have attracted intensive interests due to their unique optical, transport, and interfacial properties. The laterally stitched heterojunction based on dissimilar 2D transition metal dichalcogenides forms an intrinsic p–n junction without the necessity of applying an external voltage. However, no scalable processes are reported to construct the devices with such lateral heterostructures. Here, a scalable strategy, two‐step and location‐selective chemical vapor deposition, is reported to synthesize self‐aligned WSe₂–MoS₂ monolayer lateral heterojunction arrays and demonstrates their light‐emitting devices. The proposed fabrication process enables the growth of high‐quality interfaces and the first successful observation of electroluminescence at the WSe₂–MoS₂ lateral heterojunction. The electroluminescence study has confirmed the type‐I alignment at the interface rather than commonly believed type‐II alignment. This self‐aligned growth process paves the way for constructing various 2D lateral heterostructures in a scalable manner, practically important for integrated 2D circuit applications.     

Metal‐Guided Selective Growth of 2D Materials: Demonstration of a Bottom‐Up CMOS Inverter

2D transition metal dichalcogenide (TMD) layered materials are promising for future electronic and optoelectronic applications. The realization of large‐area electronics and circuits strongly relies on wafer‐scale, selective growth of quality 2D TMDs. Here, a scalable method, namely, metal‐guided selective growth (MGSG), is reported. The success of control over the transition‐metal‐precursor vapor pressure, the first concurrent growth of two dissimilar monolayer TMDs, is demonstrated in conjunction with lateral or vertical TMD heterojunctions at precisely desired locations over the entire wafer in a single chemical vapor deposition (VCD) process. Owing to the location selectivity, MGSG allows the growth of p‐ and n‐type TMDs with spatial homogeneity and uniform electrical performance for circuit applications. As a demonstration, the first bottom‐up complementary metal‐oxide‐semiconductor inverter based on p‐type WSe₂ and n‐type MoSe₂ is achieved, which exhibits a high and reproducible voltage gain of 23 with little dependence on position.     

Genome-wide association study for age at puberty and resumption of cyclicity in a crossbred dairy cattle population

Fertility is of primary economic importance in dairy cattle and the most common reason for involuntary culling. However, standard fertility traits have very low heritability that renders genetic selection slow and difficult. In this study, we explored fertility from an endocrine standpoint. A total of 1,163 crossbred Holstein-Normande females in a 3-generation familial design were studied for progesterone level measured every 10 d to determine age at puberty (PUB) and commencement of postpartum luteal activity (CPLA). Genetic parameters were estimated using REML with WOMBAT software. The heritability estimates were 0.38 ± 0.10 and 0.16 ± 0.07 for PUB and CPLA, respectively. Moreover, the 2 traits were genetically correlated (0.45 ± 0.23), suggesting a partially common determinism. Because of the family structure, a linkage disequilibrium and linkage analysis approach was preferred over standard genome-wide association study to map genomic regions associated with these traits. Ten quantitative trait loci (QTL) were detected for PUB on chromosomes 1, 3, 11, 13, 14, 21, and 29, whereas 3 QTL were associated with CPLA on chromosomes 21 and 26. Only the QTL on chromosome 21 was common to both traits. Four functional candidate genes (NCOA2, GAS2, OVOL1, and FOSL1) were identified in the detected regions. These findings will contribute to a clearer understanding of fertility determinism and enhance the value of introducing endocrinological data in fertility studies.     

Role of Boron in the Tribochemistry of Thermal Films Formed in the Presence of ZnDTP and Dispersant Additives

Thermally formed, additive-derived films are often a key precursor to tribologically protective films that are formed under the influence of mechanical stress. We have examined the tribological stability of model thermal films, tested in pure base oil under severe experimental conditions. Our aim was to exclude the self-healing mechanism of the protective film, which would be expected in a fully formulated lubricant. The thermal films were grown in the presence of various oil formulations containing combinations of ZnDTP and dispersants. The films were fully characterized by means of scanning electron microscopy and atomic force microscopy (for investigating the film morphology) in combination with X-ray photoelectron spectroscopy (for determining the chemical composition and thickness of the films). The mechanical stability of the films was evaluated via a series of tribological tests carried out applying two different contact pressures, 1.04 and 0.7 GPa, in base oil—a hydro-treated, heavy paraffinic fraction known as Yubase 4—at 100 °C. The tribological tests were performed using a ball-on-disc set-up and run until the failure of the protective film occurred. It was found that boron-containing thermal films displayed a much higher mechanical stability than their boron-free counterparts. It was also shown that the presence of boron species (8.4–11.1 at.% B) in the thermal films seems to be able to limit the formation of wear particles and prolong the lifetime of the protective coatings. Furthermore, it appears that very thin, boron-based thermal films can exhibit higher durability than films that are thicker but boron-free.     

Direct Intermolecular Force Measurements between Functional Groups and Individual Metallic or Semiconducting Single‐Walled Carbon Nanotubes

Many electronic applications of single‐walled carbon nanotubes (SWNTs) require electronic homogeneity in order to maximally exploit their outstanding properties. Non‐covalent separation is attractive as it is scalable and results in minimal alteration of nanotube properties. However, fundamental understanding of the metallicity‐dependence of functional group interactions with nanotubes is still lacking; this lack is compounded by the absence of methods to directly measure these interactions. Herein, a novel technology platform based on a recently developed atomic force microscopy (AFM) mode is reported which directly quantifies the adhesion forces between a chosen functional group and individual nanotubes of known metallicity, permitting comparisons between different metallicity. These results unambiguously show that this technology platform is able to discriminate the subtle adhesion force differences of a chosen functional group with pure metallic as opposed to pure semiconducting nanotubes. This new method provides a route towards rapid advances in understanding of non‐covalent interactions of large libraries of compounds with nanotubes of varying metallicity and diameter; presenting a superior tool to assist the discovery of more effective metallicity‐based SWNT separation agents.     

Plasminogen activator inhibitor-1 (PAI-1) is not related to response to neoadjuvant chemotherapy in breast cancer

There is no information available on the relation between response to chemotherapy and the high-risk phenotype assessed by uPA and/or PAI-1. The clinical situation of neoadjuvant chemotherapy provides a means of rapidly assessing the sensitivity of the primary tumour to cytotoxic drug regimens. The goal of the study was to assess prospectively the predictive value of PAI-1 for response to first-line chemotherapy. PAI-1 concentration was measured on hypertonic cytosolic extracts (0.4 M potassium chloride) by ELISA before chemotherapy on a drill biopsy sample of the tumour in 69 T2 and T3 breast cancer patients (median age 46 years). Oestrogen receptor (ER) (51% ER+), progesterone receptor (PR) (58% PR+), S-phase (median 4.0%) and ploidy were also assessed in the majority of cases. The clinical response to treatment was evaluated after four cycles of FAC or FEC regimen (5-fluorouracil, epidoxorubicin or doxorubicin and cyclophosphamide) (one cycle every 4th week). PAI-1 could be assayed in 29 post-chemotherapy surgical samples. The objective response rate (complete response plus partial response) was 59% (41 out of 69). PAI-1 expressed as gram of tissue (range 19-2370 ng g(-1) tissue) was highly correlated (r = 0.98) to PAI-1 expressed as mg protein (range 0.5-68 ng mg(-1) protein). No correlation between PAI-1 level and response could be observed, with any cut-off. The post- and pre-chemotherapy PAI-1 levels were correlated (r = 0.66). Of all biological parameters, only high S-phase (cut-off 5%) was slightly correlated (chi2 = 3.91, P = 0.05) to response. These data suggest that PAI-1 is not a predictive marker of response to chemotherapy in breast cancer and that its level is not altered by neoadjuvant chemotherapy.