Van der Waals Schottky Junction Photodetector with Ultrahigh Rectifying Ratio and Switchable Photocurrent Generation.

Metal-semiconductor junctions play an important role in the development of electronic and optoelectronic devices. A Schottky junction photodetector based on two-dimensional (2D) materials is promising for self-powered photodetection with fast response speed and large signal-to-noise ratio. However, it usually suffers from an uncontrolled Schottky barrier due to the Fermi level pinning effect arising from the interface states. In this work, all-2D Schottky junctions with near-ideal Fermi level depinning are realized, attributed to the high-quality interface between 2D semimetals and semiconductors. We further demonstrate asymmetric diodes based on multilayer graphene/MoS2/PtSe2 with a current rectification ratio exceeding 105 and an ideality factor of 1.2. Scanning photocurrent mapping shows that the photocurrent generation mechanism in the heterostructure switches from photovoltaic effect to photogating effect at varying drain biases, indicating both energy conversion and optical sensing are realized in a single device. In the photovoltaic mode, the photodetector is self-powered with a response time smaller than 100 µs under the illumination of a 405 nm laser. In the photogating mode, the photodetector exhibits a high responsivity up to 460 A/W originating from a high photogain. Finally, the photodetector is employed for single-pixel imaging, demonstrating its high-contrast photodetection ability. This work provides insight into the development of high-performance self-powered photodetectors based on 2D Schottky junctions.

Effects of less invasive surfactant administration versus intubation-surfactant-extubation on bronchopulmonary dysplasia in preterm infants with respiratory distress syndrome: a single-center, retrospective study from China.

BACKGROUND: This study evaluated the effects of less invasive surfactant administration (LISA) and intubation-surfactant-extubation (InSurE) on bronchopulmonary dysplasia (BPD) in preterm infants with respiratory distress syndrome (RDS). METHODS: Neonates with respiratory distress syndrome requiring surfactant, with gestational age < 32 weeks and birth weight < 1500 g admitted to our neonatal intensive care unit from January 2018 to December 2019, were retrospectively analyzed. LISA and InSurE were used independently. The incidence of BPD at 36 weeks postmenstrual age, pre-discharge mortality, and need for mechanical ventilation (MV) within 72 h of birth were compared between LISA and InSurE group. Secondary outcomes including necrotizing enterocolitis requiring surgery, retinopathy of prematurity ≥ stage 3, patent ductus arteriosus requiring medical therapy or surgery, and length of hospitalization were analyzed. RESULTS: Among the 148 included neonates, there were 46 and 102 infants in LISA group and InSurE group, respectively. There were no significant differences in BPD incidence, the severity of BPD at 36 weeks postmenstrual age, and the rate of MV within the first 72 h after birth between the two groups (P > 0.05, respectively). The incidences of necrotizing enterocolitis requiring surgery, retinopathy of prematurity ≥ stage 3, patent ductus arteriosus requiring medical therapy or surgery, and length of hospitalization did not differ significantly between the two groups (P > 0.05, respectively). CONCLUSIONS: For surfactant administration among preterm infants with respiratory distress syndrome, LISA did not decrease bronchopulmonary dysplasia and severity of BPD at 36 weeks postmenstrual age. The benefits of LISA would require further evaluations.

[Study on difference of effect of Huoxue drugs and Yiqi Huoxue drugs on tumor metastasis based on immune remodeling].

Tumor metastasis is an important cause of tumor treatment failure. Its molecular mechanism is closely related to tumor cells remodeling immune cells and immunosuppressive microenvironment, so as to create a suitable soil for tumor cell invasion and growth. "Huoxue Huayu" is one of the important therapeutic principles in cancer treatment, but the influence of Huoxue drugs on tumor metastasis has been controversial in clinical application. In this paper, we systematically summarized the comparative study of Huoxue drugs and Yiqi Huoxue drugs in tumor metastasis in recent years, and discussed the differences of molecular mechanisms of Huoxue drugs and Yiqi Huoxue drugs in anti-tumor metastasis from the perspective of immune remodeling, so as to provide scientific basis for clinical rational application of Huoxue drugs and Yiqi Huoxue drugs.

[Exploration and practice of post-marketing survival benefit evaluation of Chinese patent medicine for cancer].

Traditional Chinese medicine(TCM) is an important feature of cancer treatment in China. The methods to tap the advantages of TCM, reasonably evaluate and accurately apply Chinese patent medicines have become current research hotspots and difficulties. TCM takes syndrome differentiation and treatment as the core, with the characteristics of overall regulation and multi-targets efficacy. Therefore, the post-marketing survival benefit evaluation of Chinese patent medicines for cancer is different from that in modern medicine. The primary treatment goals in cancer patients include to improve the disease control rate and prolong their survival time. At present, Chinese patent medicines for cancer patients are lacking indepth studies on survival benefit at the post-marketing stage. In addition, the characteristics of individualized treatment with TCM have also increased the complexity of clinical research on TCM. Therefore, it is of certain practical significance and necessity to evaluate the survival benefit of Chinese patent medicines for cancer after marketing. Based on this, in this paper, we first summarized the technical methodological means of survival benefit evaluation at this stage, and then explored the post-marketing survival benefit evaluation of Chinese patent medicines for cancer from three aspects: the evaluation of cancer treatment effect based on survival time and quality of life, treatment-related toxicity and the auxiliary effect of TCM, and the improvement effect for tumor-related symptoms. Based on the practices of early clinical researches, and according to the insufficient efficacy evaluation of current clinical research on Chinese patent medicines, this paper proposed to improve the evaluation system for clinical researches on Chinese patent medicines, establish the evaluation method with TCM characteristics, clarify the dominant population, lay a theoretical foundation for the evaluation of post-marketing survival benefits of Chinese patent medicines for cancer in the future, and promote the modernization process of TCM.

Electrical Rectifying and Photosensing Property of Schottky Diode Based on MoS2.

Heterojunction based on two-dimensional (2D) layered materials is an emerging topic in the field of nanoelectronics and optoelectronics. Here, molybdenum sulfide (MoS2)-based Schottky diodes were fabricated using the field-effect transistor configuration with asymmetric metal contact structure. Gold and chromium electrodes were employed as drain and source electrodes to form Ohmic and Schottky contact with MoS2, respectively. The devices exhibited electrical rectifying characteristic with the current rectifying ratio exceeding 103 and an ideal factor of 1.5. A physics model of the band diagram was proposed to analyze the gate-tunable rectifying behavior of the device. The dynamic rectification based on the diode circuit was further realized with the operating frequency up to 100 Hz. The devices were also demonstrated to show different sensitivities to the light under external biases in the opposite directions, with the highest photoresponsivity reaching 1.1 × 104 A/W and specific detectivity up to 8.3 × 1012 Jones at a forward drain bias of 10 V. This kind of 2D material-based Schottky diodes have the advantage of simplicity in design and fabrication, as well as superior electrical rectifying and photosensing characteristics, which have great potential for future integrated electronic and optoelectronic applications.

Broadband MoS2 Field-Effect Phototransistors: Ultrasensitive Visible-Light Photoresponse and Negative Infrared Photoresponse.

Inverse photoresponse is discovered from phototransistors based on molybdenum disulfide (MoS2 ). The devices are capable of detecting photons with energy below the bandgap of MoS2 . Under the illumination of near-infrared (NIR) light at 980 and 1550 nm, negative photoresponses with short response time (50 ms) are observed for the first time. Upon visible-light illumination, the phototransistors exhibit positive photoresponse with ultrahigh responsivity on the order of 104 -105 A W-1 owing to the photogating effect and charge trapping mechanism. Besides, the phototransistors can detect a weak visible-light signal with effective optical power as low as 17 picowatts (pW). A thermally induced photoresponse mechanism, the bolometric effect, is proposed as the cause of the negative photocurrent in the NIR regime. The thermal energy of the NIR radiation is transferred to the MoS2 crystal lattice, inducing lattice heating and resistance increase. This model is experimentally confirmed by low-temperature electrical measurements. The bolometric coefficient calculated from the measured transport current change with temperature is -33 nA K-1 . These findings offer a new approach to develop sub-bandgap photodetectors and other novel optoelectronic devices based on 2D layered materials.

Investigation of simultaneously existed Raman scattering enhancement and inhibiting fluorescence using surface modified gold nanostars as SERS probes.

One of the main challenges for highly sensitive surface-enhanced Raman scattering (SERS) detection is the noise interference of fluorescence signals arising from the analyte molecules. Here we used three types of gold nanostars (GNSs) SERS probes treated by different surface modification methods to reveal the simultaneously existed Raman scattering enhancement and inhibiting fluorescence behaviors during the SERS detection process. As the distance between the metal nanostructures and the analyte molecules can be well controlled by these three surface modification methods, we demonstrated that the fluorescence signals can be either quenched or enhanced during the detection. We found that fluorescence quenching will occur when analyte molecules are closely contacted to the surface of GNSs, leading to a ~100 fold enhancement of the SERS sensitivity. An optimized Raman signal detection limit, as low as the level of 10-11 M, were achieved when Rhodamine 6 G were used as the analyte. The presented fluorescence-free GNSs SERS substrates with plentiful hot spots and controllable surface plasmon resonance wavelengths, fabricated using a cost-effective self-assembling method, can be very competitive candidates for high-sensitive SERS applications.

Influence of psychiatric diagnosis on treatment uptake and interferon side effects in patients with hepatitis C.

BACKGROUND AND AIM: Pegylated-interferon-α/ribavirin (PEG-IFN/RBV) treatment can cure hepatitis C virus (HCV) infection but has frequent neuropsychiatric side-effects. Patients with pre-existing psychiatric illness may not be offered therapy. We established prevalence of self-reported psychiatric comorbidity among HCV-infected patients in a hospital-liver clinic, and determined the impact of such diagnoses on uptake and tolerance to PEG-IFN/RBV. METHODS: All HCV cases referred for assessment in Australian Capital Territory/surrounding regions April 2004-March 2012 were entered into a clinical database. We conducted univariate and multivariate analyses of variables correlating with uptake of antiviral therapy and frequency of treatment-related side-effects. RESULTS: Of 773 referred patients, 235 (30%) described pre-existing psychiatric illness. Among these, 26% received antiviral therapy, compared with 30% of 538 without psychiatric comorbidity. History of depression (usually validated by liaison psychiatry) was associated with higher incidence of treatment-related neuropsychiatric side-effects (odds ratio 2.79 [1.35-5.70], P < 0.05) but did not affect treatment outcome. Twenty-seven patients reported schizophrenia: three (11%) received antiviral therapy, compared with 30% admitting depression and 20% with bipolar affective disorder (all assessed by psychiatrist). In most schizophrenia cases, the reason for not offering antiviral treatment was psychological illness, yet none of five treated (these three plus two others in a psychiatric rehabilitation facility) experienced worsening psychiatric symptoms. CONCLUSIONS: A history of depression is common with hepatitis C but does not affect initiation of antiviral treatment, despite substantially increased risk of psychiatric side-effects. In contrast, pre-existing schizophrenia appears to influence treatment decisions, despite little evidence that PEG-IFN/RBV exacerbates the psychiatric condition, and well-supervised antiviral therapy can have good outcomes.

Synthesis of silver nanostructures by multistep methods.

The shape of plasmonic nanostructures such as silver and gold is vital to their physical and chemical properties and potential applications. Recently, preparation of complex nanostructures with rich function by chemical multistep methods is the hotspot of research. In this review we introduce three typical multistep methods to prepare silver nanostructures with well-controlled shapes, including the double reductant method, etching technique and construction of core-shell nanostructures. The growth mechanism of double the reductant method is that different favorable facets of silver nanocrystals are produced in different reductants, which can be used to prepare complex nanostructures such as nanoflags with ultranarrow resonant band bandwidth or some silver nanostructures which are difficult to prepare using other methods. The etching technique can selectively remove nanoparticles to achieve the aim of shape control and is widely used for the synthesis of nanoflowers and hollow nanostructures. Construction of core-shell nanostructures is another tool to control shape and size. The three methods can not only prepare various silver nanostructures with well-controlled shapes, which exhibit unique optical properties, such as strong surface-enhanced Raman scattering (SERS) signal and localized surface plasmon resonance (LSPR) effect, but also have potential application in many areas.

Investigation on the role of the molecular weight of polyvinyl pyrrolidone in the shape control of high-yield silver nanospheres and nanowires.

Serving as shape control agent, polyvinyl pyrrolidone (PVP) has been widely used in chemical synthesis of metal nanoparticles. However, the role of molecular weight (MW) of PVP has been rarely concerned. In this study, we show a facile method to control the shapes of silver nanocrystals using PVP with different MWs. PVPMW=8,000, PVPMW=29,000, PVPMW=40,000, and PVPMW=1,300,000 are compared in the present study. Surprisingly, high-yield silver rodlike nanostructures, nanospheres, and nanowires can be obtained under the same growth environment and reactant concentrations by simply changing the MW of PVP. The mechanism studies of the role of PVP with different MWs in the growth process were carried out systemically using the morphology and spectroscopic measurement, FT-IR spectrum analysis, and seed crystallization monitoring. The results indicate that the MW of PVP plays a determinant role in the morphology and optical property control of the silver nanocrystals. Meantime, the concentration of PVP was found to be an assistant factor to further improve the shape and the yield of the synthesized nanocrystals.

Integrated optical gyroscope using active long-range surface plasmon-polariton waveguide resonator.

Optical gyroscopes with high sensitivity are important rotation sensors for inertial navigation systems. Here, we present the concept of integrated resonant optical gyroscope constructed by active long-range surface plasmon-polariton (LRSPP) waveguide resonator. In this gyroscope, LRSPP waveguide doped gain medium is pumped to compensate the propagation loss, which has lower pump noise than that of conventional optical waveguide. Peculiar properties of single-polarization of LRSPP waveguide have been found to significantly reduce the polarization error. The metal layer of LRSPP waveguide is electro-optical multiplexed for suppression of reciprocal noises. It shows a limited sensitivity of ~10(-4) deg/h, and a maximum zero drift which is 4 orders of magnitude lower than that constructed by conventional single-mode waveguide.