72 research outputs found
Telluride nanocrystals with adjustable amorphous shell thickness and core-shell structure modulation by aqueous cation-exchange
Engineering the structure of core-shell colloidal semiconductor nanoparticles
(CSNPs) is attractive due to the potential to enhance photo-induced charge
transfer (PICT) and induce favourable optical and electronic properties.
Nonetheless, the sensitivity of telluride CSNPs to high temperatures makes it
challenging to precisely modulate their surface crystallinity. Herein, we have
developed an efficient strategy for synthesising telluride CSNPs with thin
amorphous shells using aqueous cation exchange (ACE). By changing the synthesis
temperature in the range 40 to 110C, the crystallinity of the CdTe
nanoparticles was controllable from perfect crystals with no detectable
amorphous shell (c-CdTe) to a core-shell structure with a crystalline CdTe NP
core covered by an amorphous shell of tunable thickness up to 7-8nm (c@a-CdTe)
. A second ACE step transformed the c@a-CdTe to crystalline CdTe@HgTe
core-shell NPs. The c@a-CdTe nanoparticles synthesized at 60C and having a 4-5
nm thick amorphous shell, exhibited the highest surface-enhanced Raman
scattering activity with a high enhancement factor around 8.82x10^5, attributed
to the coupling between the amorphous shell and the crystalline core.Comment: 15 pages, 5 figures, plus supplementary informatio
Overcoming Coulomb Interaction Improves Free-Charge Generation and Thermoelectric Properties for n-Doped Conjugated Polymers
Molecular doping of organic semiconductors creates Coulombically bound charge and counterion pairs through a charge-transfer process. However, their Coulomb interactions and strategies to mitigate their effects have been rarely addressed. Here, we report that the number of free charges and thermoelectric properties are greatly enhanced by overcoming the Coulomb interaction in an n-doped conjugated polymer. Poly(2,2'-bithiazolothienyl-4,4',10,10'-tetracarboxydiimide) (PDTzTI) and the benchmark N2200 are n-doped by tetrakis (dimethylamino) ethylene (TDAE) for thermoelectrics. Doped PDTzTI exhibits similar to 10 times higher free-charge density and 500 times higher conductivity than doped N2200, leading to a power factor of 7.6 mu W m(-1) K-2 and ZT of 0.01 at room temperature. Compared to N2200, PDTzTI features a better molecular ordering and two-dimensional charge delocalization, which help overcome the Coulomb interaction in the doped state. Consequently, free charges are more easily generated from charge-counterion pairs. This work provides a strategy for improving n-type thermoelectrics by tackling electrostatic interactions
Developing the Symptoms and Functional Impairment Rating Scale:A Multi-Dimensional ADHD Scale
Objective: This research developed a practical, multi-dimensional attention deficit hyperactivity disorder (ADHD) rating scale (i.e., the Symptoms and Functional Impairment Rating Scale, SFIRS) for Chinese children, aged 6-12 years, with ADHD. Methods: The structural validity, criterion validity, internal consistency, and test-retest reliability of the scale were evaluated. Item screening was conducted with 412 ADHD patients and 322 developmentally typical controls. Results: The scale includes 44 items, divided among Hyperactivity-Impulsivity, Self-Control, Inattention, Self-Management, Academic Performance, and Social Interaction. The six-factor model showed good data fit, with each factor significantly correlated with its corresponding criterion (r=0.690-0.841). The Cronbach's α of the full scale was 0.976. Total score test-retest reliability was r=0.816 (p<0.01). Conclusion: The SFIRS thus demonstrated good reliability and validity and may be used to assess ADHD among children aged 6-12 years in China
Ultrawideband Frequency-Selective Absorber Designed with an Adjustable and Highly Selective Notch
In this paper, the working mechanism of a wideband absorber designed with an adjustable and highly selective notch band is studied, in which the narrow notch band is independently controlled by the lower lossless layer of the absorber, while the upper lossy layer loaded with lumped resistors realizes absorption. We present two instances with geometrically controlled and electrically controlled notch bands, respectively. Without decreasing absorption performance, the notch position can be flexibly adjusted throughout the entire frequency band by simply modifying the dimension of the lossless frequency-selective surface (FSS) or changing the capacitance of the varactor, i.e., using geometric control or electrical control. The narrow notch band allows two wide absorption bands to be retained on both sides; therefore, good stealth performance is still guaranteed. Equivalent circuit models (ECM) are proposed to further explain the principle. The frequency-domain simulation, ECM, time-domain simulation, and experimental results are in good agreement and validate the adjustability and high selectivity of the notched absorbers. At the end of this paper, an FSA-backed monopole antenna is simulated and measured, which clearly illustrates that these FSAs can serve as the ground plane for antennas and realize out-of-band RCS reduction
Leaf nutrient traits of planted forests demonstrate a heightened sensitivity to environmental changes compared to natural forests
Leaf nutrient content (nitrogen, phosphorus) and their stoichiometric ratio (N/P) as key functional traits can reflect plant survival strategies and predict ecosystem productivity responses to environmental changes. Previous research on leaf nutrient traits has primarily focused on the species level with limited spatial scale, making it challenging to quantify the variability and influencing factors of forest leaf nutrient traits on a macro scale. This study, based on field surveys and literature collected from 2005 to 2020 on 384 planted forests and 541 natural forests in China, investigates the differences in leaf nutrient traits between forest types (planted forests, natural forests) and their driving factors. Results show that leaf nutrient traits (leaf nitrogen content (LN), leaf phosphorus content (LP), and leaf N/P ratio) of planted forests are significantly higher than those of natural forests (P< 0.05). The impact of climatic and soil factors on the variability of leaf nutrient traits in planted forests is greater than that in natural forests. With increasing forest age, natural forests significantly increase in leaf nitrogen and phosphorus content, with a significant decrease in N/P ratio (P< 0.05). Climatic factors are key environmental factors dominating the spatial variability of leaf nutrient traits. They not only directly affect leaf nutrient traits of planted and natural forest communities but also indirectly through regulation of soil nutrients and stand factors, with their direct effects being more significant than their indirect effects
Profiling the peripheral blood T cell receptor repertoires of gastric cancer patients
Cancer driven by somatic mutations may express neoantigens that can trigger T-cell immune responses. Since T-cell receptor (TCR) repertoires play critical roles in anti-tumor immune responses for oncology, next-generation sequencing (NGS) was used to profile the hypervariable complementarity-determining region 3 (CDR3) of the TCR-beta chain in peripheral blood samples from 68 gastric cancer patients and 49 healthy controls. We found that most hyper-expanded CDR3 are individual-specific, and the gene usage of TRBV3-1 is more frequent in the tumor group regardless of tumor stage than in the healthy control group. We identified 374 hyper-expanded tumor-specific CDR3, which may play a vital role in anti-tumor immune responses. The patients with stage IV gastric cancer have higher EBV-specific CDR3 abundance than the control. In conclusion, analysis of the peripheral blood TCR repertoires may provide the biomarker for gastric cancer prognosis and guide future immunotherapy
The NLRP3 inflammasome is involved in resident intruder paradigm-induced aggressive behaviors in mice
Background: Aggressive behaviors are one of the most important negative behaviors that seriously endangers human health. Also, the central para-inflammation of microglia triggered by stress can affect neurological function, plasticity, and behavior. NLRP3 integrates stress-related signals and is a key driver of this neural para-inflammation. However, it is unclear whether the NLRP3 inflammasome is implicated in the development of aggressive behaviors.Methods: First, aggressive behavior model mice were established using the resident intruder paradigm. Then, aggressive behaviors were determined with open-field tests (OFT), elevated plus-maze (EPM), and aggressive behavior tests (AT). Moreover, the expression of P2X7R and NLRP3 inflammasome complexes were assessed by immunofluorescence and Western blot. The levels of NLRP3 and inflammatory cytokines were evaluated using enzyme-linked immunosorbent assay (ELISA) kits. Finally, nerve plasticity damage was observed by immunofluorescence, transmission electron microscope, and BrdU staining.Results: Overall, the resident intruder paradigm induced aggressive behaviors, activated the hippocampal P2X7R and NLRP3 inflammasome, and promoted the release of proinflammatory cytokines IL-1β in mice. Moreover, NLRP3 knockdown, administration of P2X7R antagonist (A804598), and IL-1β blocker (IL-1Ra) prevented NLRP3 inflammasome-driven inflammatory responses and ameliorated resident intruder paradigm-induced aggressive behaviors. Also, the resident intruder paradigm promoted the activation of mouse microglia, damaging synapses in the hippocampus, and suppressing hippocampal regeneration in mice. Besides, NLRP3 knockdown, administration of A804598, and IL-1Ra inhibited the activation of microglia, improved synaptic damage, and restored hippocampal regeneration.Conclusion: The NLRP3 inflammasome-driven inflammatory response contributed to resident intruder paradigm-induced aggressive behavior, which might be related to neuroplasticity. Therefore, the NLRP3 inflammasome can be a potential target to treat aggressive behavior-related mental illnesses
The ALMA Survey of Star Formation and Evolution in Massive Protoclusters with Blue Profiles (ASSEMBLE): Core Growth, Cluster Contraction, and Primordial Mass Segregation
The ALMA Survey of Star Formation and Evolution in Massive Protoclusters with
Blue Profiles (ASSEMBLE) aims to investigate the process of mass assembly and
its connection to high-mass star formation theories in protoclusters in a
dynamic view. We observed 11 massive (Mclump>1000 Msun), luminous (Lbol>10,000
Lsun), and blue-profile (infall signature) clumps by ALMA with resolution of
2200-5500 au at 350 GHz (870 um) in continuum and line emission. 248 dense
cores were identified, including 106 cores showing protostellar signatures and
142 prestellar core candidates. Compared to early-stage infrared dark clouds
(IRDCs) by ASHES, the core mass and surface density within the ASSEMBLE clumps
exhibited significant increment, suggesting concurrent core accretion during
the evolution of the clumps. The maximum mass of prestellar cores was found to
be 2 times larger than that in IRDCs, indicating evolved protoclusters have the
potential to harbor massive prestellar cores. The mass relation between clumps
and their most massive core (MMCs) is observed in ASSEMBLE but not in IRDCs,
which is suggested to be regulated by multiscale mass accretion. The mass
correlation between the core clusters and their MMCs has a steeper slope
compared to that observed in stellar clusters, which can be due to
fragmentation of the MMC and stellar multiplicity. We observe a decrease in
core separation and an increase in central concentration as protoclusters
evolve. We confirm primordial mass segregation in the ASSEMBLE protoclusters,
possibly resulting from gravitational concentration and/or gas accretion.Comment: 37 pages, 13 figures, 5 tables; accepted for publication in ApJ
- …