E-Band InAs Quantum Dot Micro-Disk Laser with Metamorphic InGaAs Layers Grown on GaAs/Si (001) Substrate.

The direct growth of III-V quantum dot (QD) lasers on silicon substrate has been rapidly developing over the past decade and has been recognized as a promising method for achieving on-chip light sources in photonic integrated circuits (PICs). Up to date, O- and C/L-bands InAs QD lasers on Si have been extensively investigated, but as an extended telecommunication wavelength, the E-band QD lasers directly grown on Si substrates are not available yet. Here, we demonstrate the first E-band (1365 nm) InAs QD micro-disk lasers epitaxially grown on Si (001) substrates by using a III-V/IV hybrid dual-chamber molecular beam epitaxy (MBE) system. The micro-disk laser device on Si was characterized with an optical threshold power of 0.424 mW and quality factor (Q) of 1727.2 at 200 K. The results presented here indicate a path to on-chip silicon photonic telecom-transmitters.

Monolithic integration of embedded III-V lasers on SOI.

Silicon photonic integration has gained great success in many application fields owing to the excellent optical device properties and complementary metal-oxide semiconductor (CMOS) compatibility. Realizing monolithic integration of III-V lasers and silicon photonic components on single silicon wafer is recognized as a long-standing obstacle for ultra-dense photonic integration, which can provide considerable economical, energy-efficient and foundry-scalable on-chip light sources, that has not been reported yet. Here, we demonstrate embedded InAs/GaAs quantum dot (QD) lasers directly grown on trenched silicon-on-insulator (SOI) substrate, enabling monolithic integration with butt-coupled silicon waveguides. By utilizing the patterned grating structures inside pre-defined SOI trenches and unique epitaxial method via hybrid molecular beam epitaxy (MBE), high-performance embedded InAs QD lasers with monolithically out-coupled silicon waveguide are achieved on such template. By resolving the epitaxy and fabrication challenges in such monolithic integrated architecture, embedded III-V lasers on SOI with continuous-wave lasing up to 85 °C are obtained. The maximum output power of 6.8 mW can be measured from the end tip of the butt-coupled silicon waveguides, with estimated coupling efficiency of approximately -6.7 dB. The results presented here provide a scalable and low-cost epitaxial method for the realization of on-chip light sources directly coupling to the silicon photonic components for future high-density photonic integration.

Reduced Dislocation of GaAs Layer Grown on Ge-Buffered Si (001) Substrate Using Dislocation Filter Layers for an O-Band InAs/GaAs Quantum Dot Narrow-Ridge Laser.

The development of the low dislocation density of the Si-based GaAs buffer is considered the key technical route for realizing InAs/GaAs quantum dot lasers for photonic integrated circuits. To prepare the high-quality GaAs layer on the Si substrate, we employed an engineered Ge-buffer on Si, used thermal cycle annealing, and introduced filtering layers, e.g., strained-layer superlattices, to control/reduce the threading dislocation density in the active part of the laser. In this way, a low defect density of 2.9 × 107 cm-2 could be achieved in the GaAs layer with a surface roughness of 1.01 nm. Transmission electron microscopy has been applied to study the effect of cycling, annealing, and filtering layers for blocking or bending threading-dislocation into the InAs QDs active region of the laser. In addition, the dependence of optical properties of InAs QDs on the growth temperature was also investigated. The results show that a density of 3.4 × 1010 InAs quantum dots could be grown at 450 °C, and the photoluminescence exhibits emission wavelengths of 1274 nm with a fullwidth at half-maximum (FWHM) equal to 32 nm at room temperature. The laser structure demonstrates a peak at 1.27 µm with an FWHM equal to 2.6 nm under a continuous-wave operation with a threshold current density of ∼158 A/cm2 for a 4-µm narrow-ridge width InAs QD device. This work, therefore, paves the path for a monolithic solution for photonic integrated circuits when III-V light sources (which is required for Si photonics) are grown on a Ge-platform (engineered Ge-buffer on Si) for the integration of the CMOS part with other photonic devices on the same chip in near future.

The current-voltage measurements under flat-top pulsed magnetic fields for non-ohmic transport study.

Investigation of the non-ohmic transport behaviors under high magnetic fields can provide a new way to explore novel field-induced phenomena. We present the current-voltage measurements under high magnetic fields based on the flat-top pulsed magnetic field system. Two different measurement strategies were compared, given that the excitation current swept continuously or increased by a series of pulses. For the short duration of the flat-top pulsed field, the continuous current method was adopted and well optimized to reduce the Joule heating and achieve the quasi-static measurements. Finally, the non-ohmic behaviors of a quasi-one-dimensional charge density wave Li0.9Mo6O17 were successfully studied under the magnetic field up to 30 T at 4.2 K, which was the first current-voltage measurements carried out in pulsed magnetic fields.

Integrating Self-determination Theory and Upper Limb Factors to Predict Physical Activity in Patients With Breast Cancer During Chemotherapy.

BACKGROUND: Some empirical investigations try to describe the factors that affect the physical activity of breast cancer survivors, but these investigations rarely focus on the basic psychological needs or motivation regulation of breast cancer survivors in physical activity. OBJECTIVE: The aim of this study was to construct structural equation modeling of the self-determination theory and upper limb factors to predict the physical activity of breast cancer patients during chemotherapy. METHODS: A total of 236 breast cancer survivors completed measures of basic psychological needs, behavioral regulation in exercise, symptoms and dysfunction of upper limb factors, and physical activity. Path analyses structured the direct and indirect effects (via motivational orientations) of basic psychological needs and upper limb factors on physical activity. RESULTS: A total of 216 (91.5%) participants met the standard physical activity metabolic equivalent recommended. The final model has a good degree of fit (χ2 = 809.363, df = 391, χ2/df ≤ 2.07 [1-3]; root-mean-square error of approximation, 0.067 [<0.008]). The competence (0.309) of basic psychological needs and amotivation (-0.38) of motivation regulations have the greatest effect on physical activity. CONCLUSIONS: Competence is the most important basic psychological need of breast cancer patients during chemotherapy, and amotivation is the most important motivation regulation. IMPLICATIONS FOR PRACTICE: Nurses need to pay more attention to the basic psychological needs and the motivation regulation in breast cancer patients during chemotherapy. Randomized controlled trials of breast cancer survivor interventions based on the self-determination theory are needed.

P-doped 1300 nm InAs/GaAs quantum dot lasers directly grown on an SOI substrate.

The realization of monolithic integration of a stable III-V laser on a standard silicon-on-insulator (SOI) substrate has been regarded as a challenging technology for silicon-based photonic integration circuits (PICs). Here, we successfully demonstrated the electrically pumped P-doped 1300 nm InAs/GaAs quantum dot (QD) laser epitaxially grown on {111}-faceted SOI hollow substrates. These III-V QD lasers, which are epitaxially grown on an SOI substrate, generally exhibit strong thermal accumulation due to the oxide layer underneath. By applying a double-side heat dissipation design, the maximum operation temperature of the SOI-based InAs/GaAs QD laser under a continuous-wave (CW) operation mode is ramped up to 35°C from 20°C. Moreover, the thermal profile simulation of three different structures has also been carried out to show the effectiveness of the top heat sink design in order to improve laser performance. An integrated thermal shunt design is proposed to improve heat dissipation without using the external top heat sink. The successful realization of room-temperature SOI-based InAs/GaAs QD lasers pave a viable way for integrating light sources in PICs.

InAs/GaAs quantum dot single-section mode-locked lasers on Si (001) with optical self-injection feedback.

Silicon based InAs quantum dot mode locked lasers (QD-MLLs) are promising to be integrated with silicon photonic integrated circuits (PICs) for optical time division multiplexing (OTDM), wavelength division multiplexing (WDM) and optical clocks. Single section QD-MLL can provide high-frequency optical pulses with low power consumption and low-cost production possibilities. However, the linewidths of the QD-MLLs are larger than quantum well lasers, which generally introduce additional phase noise during optical transmission. Here, we demonstrated a single section MLL monolithically grown on Si (001) substrate with a repetition rate of 23.5 GHz. The 3-dB Radio Frequency (RF) linewidth of the QD-MLL was stabilized at optimized injection current under free running mode. By introducing self-injection feedback locking at a feedback strength of -24dB, the RF linewidth of MLL was significantly narrowed by two orders of magnitude from 900kHz to 8kHz.

InAs/GaAs quantum dot narrow ridge lasers epitaxially grown on SOI substrates for silicon photonic integration.

Monolithic integration of III-V laser sources on standard silicon-on-insulator (SOI) substrate has been recognized as an enabling technology for realizing Si-based photonic integration circuits (PICs). The Si-based ridge lasers employing III-V quantum dot (QD) materials are gaining significant momentum as it allows massive-scalable, streamlined fabrication of Si photonic integrated chips to be made cost effectively. Here, we present the successful fabrication of InAs/GaAs QD ridge lasers monolithically grown on {111}-faceted SOI hollow substrates. The as-cleaved Fabry-Perot (FP) narrow ridge laser is achieved with a relatively low threshold current of 50 mA at room temperature under pulse current operation. The maximum working temperature achieved is up to 80 oC. The promising lasing characteristics of such SOI-based InAs/GaAs QD ridge lasers with low threshold current and small footprint provide a viable route towards large-scale, low-cost integration of laser sources on SOI platform for silicon photonic integration purpose.

Research trends and hotspots in caregiver studies: A bibliometric and scientometric analysis of nursing journals.

AIMS: To explore the intellectual landscape of care-giving studies and identify research trends and hotspots in this field. DESIGN: A bibliometric and scientometric analysis of care-giving literature was undertaken from January - February 2020. METHODS: CiteSpace was used to analyse research published between 1900 - 2019. A references-based co-citation analysis was used to identify the intellectual landscape of care-giving research. A keywords-based co-occurrence analysis with citation bursts was used to explore research hotspots and frontiers. Lastly, a co-authorship network analysis was used to identify co-operation among authors, countries, and institutions. RESULTS: There has been an increasing trend in the number of publications on care-giving research with light fluctuations. Relevant literature mainly focused on the fields of oncology and psychiatry. The keywords-based analysis indicated that the main research targets had previously been informal caregivers of patients with stroke, Alzheimer's disease, and schizophrenia. In recent years, focus has shifted onto informal caregivers of patients with cancer, heart failure, and those at end-of-life. CONCLUSION: This bibliometric and scientometric analysis helps us understand the current state of caregiver research and its recent developments. IMPACT: Caregivers' mental health and care experience have become research hotspots. WHERE AND ON WHOM WILL THE RESEARCH HAVE AN IMPACT?: This research allows the development of future research on care-giving. Future researchers should explore effective interventions for the health of patient-caregiver dyads.

Assembly of SPS/MgSi assisted by dopamine with excellent removal performance for ciprofloxacin.

In this work, magnesium silicate-based sulfonated polystyrene sphere composites (SPS/MgSi) were synthesized by one-step (SMD1) and two-step (SMD2) methods. For SMD1, MgSi particles were densely assembled on the surface of SPS, assisted by complexation between Fe3+ and hydroxyl phenol. For SMD2, SPS/SiO2 was firstly obtained by the same method as SMD1, and then SPS/SiO2 was transformed directly to SPS/MgSi under hydrothermal conditions. Therefore, MgSi obtained by the two-step method had an interwoven structure. Compared to SPS, MgSi and SMD1, SMD2 presented a larger specific surface area and more negative surface charges. Therefore, SMD2 showed superior adsorption performance toward CIP with concentrations of 5, 10 and 50 mg/L, and for 50 mg/L, the equilibrium adsorption capacity could reach 329.7 mg/g. The adsorption process is fast and can be described by the pseudo-second-order kinetic model. The relationship between pH value and Zeta potential demonstrated that electrostatic interaction dominated the adsorption process. In addition, competitive adsorption showed that the effect of Na+ was negligible but the effect of Ca2+ was dependent on its concentration. Humid acid (HA) could slightly promote the absorption of CIP by SMD2. After five rounds of adsorption-desorption, the equilibrium adsorption capacity of SMD2 still remained at 288.6 mg/L for 50 mg/L CIP. Notably, SMD2 presented likewise superior adsorption capacity for CIP with concentrations of 10 and 50 mg/L in Minjiang source water. All the results indicated that this synthesis method is universal and that SMD2 has potential as an adsorbent for CIP removal from aquatic environments.

Phosphorus-free 1.5 µm InAs quantum-dot microdisk lasers on metamorphic InGaAs/SOI platform.

III-V semiconductor lasers epitaxially grown on silicon, especially on a silicon-on-insulator (SOI) platform, have been considered one of the most promising approaches to realize an integrated light source for silicon photonics. Although notable achievements have been reported on InP-based 1.5 µm III-V semiconductor lasers directly grown on silicon substrates, phosphorus-free 1.5 µm InAs quantum dot (QD) lasers on both silicon and SOI platforms are still uncharted territory. In this work, we demonstrate, to the best of our knowledge, the first phosphorus-free InAs QD microdisk laser epitaxially grown on SOI substrate emitting at the telecommunications S-band by growing metamorphic InAs/InGaAs QDs on (111)-faceted SOI hollow structures. The lasing threshold power for a seven-layer InAs QD microdisk laser with a diameter of 4 µm is measured as 234 µW at 200 K. For comparison, identical microdisk lasers grown on GaAs substrate are also characterized. The results obtained pave the way for an on-chip 1.5 µm light source for long-haul telecommunications.

1310 nm InAs quantum-dot microdisk lasers on SOI by hybrid epitaxy.

Direct epitaxial growth of O-band InAs/GaAs quantum-dot laser on Si substrates has been rapidly developing over the past few years. But most of current methodologies are not fully compatible with silicon-on-insulator (SOI) technology, which is the essential platform for silicon photonic devices. By implementing an in situ III-V/Si hybrid growth technique with (111)-faceted Si hollow structures, we demonstrate the first optically pumped InAs/GaAs quantum-dot microdisk laser on SOI substrates grown by molecular beam epitaxy (MBE). The microdisk laser on SOI is characterized with threshold pump power as low as 0.39 mW and a Q factor of 3900 at room temperature. Additionally, the compared device performance of InAs quantum-dot microdisk lasers on GaAs, Si (001) and SOI are simultaneously studied with identical epi-structures.

Fluorescence resonance energy transfer aptasensor between nanoceria and graphene quantum dots for the determination of ochratoxin A.

In the present work, colloidal cerium oxide nanoparticles (nanoceria) and graphene quantum dots (GQDs) were firstly synthesized by sol-gel method and pyrolysis respectively, which all have a uniform nano-size and significant fluorescence emission. Due to the fluorescence emission spectrum of nanoceria overlapped the absorption spectrum of GQDs, fluorescence resonance energy transfer (FRET) between nanoceria and GQDs could occur effectively by the electrostatic interaction. Based on it, a sensitive ratiometric fluorescence aptasensor for the determination of ochratoxin A (OTA), a small molecular mycotoxin produced by Aspergillus and Penicillium strains, has been successfully constructed. In which, probe DNA1@nanoceria and DNA2@GQD were designed to complementary with OTA aptamer, both could adsorb each other, leading to the occur of FRET. After adding of OTA aptamer and then introducing of OTA, the FRET would be interrupted/recovered due to the specific affinity of OTA and its aptamer, the fluorescence recovery value would increase with the addition of OTA. Under the optimal experimental conditions (pH 7, mGQD/nanoceria 2, captamer 100 nM, incubation time 30 min), the constructed ratiometric fluorescence aptasensor exhibited a satisfying linear range (0.01-20 ng mL-1), low limit of detection (2.5 pg mL-1) and good selectivity towards OTA, and has been successfully applied for the analysis of real sample peanuts with good accuracy of the recoveries ranged from 90 to 110%.

Regional ambient temperature is associated with human personality.

Human personality traits differ across geographical regions 1-5 . However, it remains unclear what generates these geographical personality differences. Because humans constantly experience and react to ambient temperature, we propose that temperature is a crucial environmental factor that is associated with individuals' habitual behavioural patterns and, therefore, with fundamental dimensions of personality. To test the relationship between ambient temperature and personality, we conducted two large-scale studies in two geographically large yet culturally distinct countries: China and the United States. Using data from 59 Chinese cities (N = 5,587), multilevel analyses and machine learning analyses revealed that compared with individuals who grew up in regions with less clement temperatures, individuals who grew up in regions with more clement temperatures (that is, closer to 22 °C) scored higher on personality factors related to socialization and stability (agreeableness, conscientiousness, and emotional stability) and personal growth and plasticity (extraversion and openness to experience). These relationships between temperature clemency and personality factors were replicated in a larger dataset of 12,499 ZIP-code level locations (the lowest geographical level feasible) in the United States (N = 1,660,638). Taken together, our findings provide a perspective on how and why personalities vary across geographical regions beyond past theories (subsistence style theory, selective migration theory and pathogen prevalence theory). As climate change continues across the world, we may also observe concomitant changes in human personality.

The 'warm' side of coldness: Cold promotes interpersonal warmth in negative contexts.

The concrete experience of physical warmth has been demonstrated to promote interpersonal warmth. This well-documented link, however, tells only half of the story. In the current study, we thus examined whether physical coldness can also increase interpersonal warmth under certain circumstances. We conducted three experiments to demonstrate that the relationship between the experience of physical temperature and interpersonal outcomes is context dependent. Experiment 1 showed that participants touching cold (vs. warm) objects were more willing to forgive a peer's dishonest behaviour. Experiment 2 demonstrated the fully interactive effect of temperature and context on interpersonal warmth: Participants touching cold (vs. warm) objects were less likely to assist an individual who had provided them with good service (positive social context), but more likely to assist an individual who had provided them with poor service (negative social context). Experiment 3 replicated the results of Experiment 2 using the likelihood to complain, a hostility-related indicator, as the dependent variable: In a pleasant queue (positive social context), participants touching cold objects were more likely to complain and those touching warm objects were less likely to complain compared with the control group. This pattern was reversed in an annoying queue (negative social context).

Non-sympathetic FRN responses to drops in others' stocks.

Previous neuroeconomic studies have observed that people display sympathetic neural responses toward others' misfortunes. We argue that the reverse emotions, such as gloating or schadenfreude, may also emerge in certain circumstances. To examine this theory, we recorded feedback-related negativity (FRN) toward others' large or small gains or losses in a stock market context. We adopted the framework of social distance, according to which we hypothesized that because others in the stock market are far away, unidentified, and indistinct, people would show less sympathy or even schadenfreude toward others' large losses. The results indicated that FRN at Fz was significantly less negative when observing larger decreases in others' stock, indicating that others' large losses are not unexpected negative events in the stock market and suggesting the existence of schadenfreude. Our research contributes to the understanding of social neurofinance by demonstrating the schadenfreude effect in relation to the stock market. This study also provides new information regarding the relationship between FRN and the social emotions that form the expectations of gain and loss.

Changes in sensory perception of sports drinks when consumed pre, during and post exercise.

The aim of this study was to examine sensory perceptions towards different formulations of sports drinks when consumed before, at various points during, and following exercise. Following familiarization 14 recreational runners underwent four trials in a single blind counterbalanced design. Each trial utilised one of four different solutions: 7.5% carbohydrate, 421 mg L(-1) electrolyte (HiC-HiE); 7.5% carbohydrate, 140 mg L(-1) electrolyte (HiC-LoE); 1.3% carbohydrate, 421 mg L(-1) electrolyte (LoC-HiE) and water. Subjects were provided with 50-ml samples to ingest and then rate (using a 100-mm line scale) the intensity of sweetness, saltiness, thirst-quenching ability and overall liking before (-30 min), during (0, 30 and 60 min) and following (90 and 120 min) treadmill running exercise. Ratings of sweetness for all energy-containing drinks were higher during exercise relative to pre- and post-exercise conditions (P<0.05); ratings also increased with duration of exercise (P<0.001). Sweetness ratings for LoC-HiE increased during exercise (P<0.05) but remained the same for other beverages. Ratings of saltiness decreased for all energy-containing drinks during exercise relative to pre-exercise (P<0.05); ratings decreased with duration of exercise in these drinks (P<0.05). Ratings of thirst-quenching ability (P=0.039) and overall liking (P=0.013) increased with duration of exercise with all beverages. Significant changes in sensory perception occur when consuming sports drinks during exercise relative to non-exercise conditions. Temporal changes also occur during exercise itself which leads to enhanced liking of all beverages.