Explore the vast range of titles available.

One-dimensional ZnO nanostructures (nanowires/nanorods) are attractive materials for applications such as gas sensors, biosensors, solar cells, and photocatalysts. This is due to the relatively easy production process of these kinds of nanostructures with excellent charge carrier transport properties and high crystalline quality. In this work, we review the photoluminescence (PL) properties of single and collective ZnO nanowires and nanorods. As different growth techniques were obtained for the presented samples, a brief review of two popular growth methods, vapor-liquid-solid (VLS) and hydrothermal, is shown. Then, a discussion of the emission process and characteristics of the near-band edge excitonic emission (NBE) and deep-level emission (DLE) bands is presented. Their respective contribution to the total emission of the nanostructure is discussed using the spatial information distribution obtained by scanning transmission electron microscopy−cathodoluminescence (STEM-CL) measurements. Also, the influence of surface effects on the photoluminescence of ZnO nanowires, as well as the temperature dependence, is briefly discussed for both ultraviolet and visible emissions. Finally, we present a discussion of the size reduction effects of the two main photoluminescent bands of ZnO. For a wide emission (near ultra-violet and visible), which has sometimes been attributed to different origins, we present a summary of the different native point defects or trap centers in ZnO as a cause for the different deep-level emission bands.

The excitation-dependent emission properties of carbon dots (Cdots) are extensively reported, but their red emission is often weak, limiting their wider application. Here we introduce ethidium bromide, as a functional precursor with red emission, to enhance the red emission for Cdots, with comparable intensity at a broad wavelength range to multi-emission Cdots (M-Cdots). We found that Cdots prepared with ethidium bromide/ethylenediamine exhibited strong blue and red emission at 440 and 615 nm, with optimal excitation at 360 and 470 nm as M-Cdots, respectively, but the Cdots from single ethidium bromide (EB-Cdots) possessed weak red emission. M-Cdots exhibited a broad absorption band at 478 nm, but a band blue-shifted to 425 nm was observed for EB-Cdots, while no absorption was observed at 478–425 nm for the Cdots prepared with citric acid and ethylenediamine. Thus, we proposed that C=O and C=N formed a π-conjugation structure as the absorption band at 478 nm for the red emission of M-Cdots, as also confirmed with the excitation at 470 nm. Moreover, the π-conjugation structure is fragile and sensitive to harsh conditions, so red emission was difficult to observe for the Cdots prepared with citric acid/ethylenediamine or single ethidium bromide. M-Cdots possess two centers for blue and red emission with different structures. The dual emission was therefore used for ratiometric sensing with dichromate (Cr2O72−) and formaldehyde (HCHO) as the targets using the intensity ratio of the emissions at 615 and 440 nm. Due to the comparable intensity at a broad wavelength range, we designed encryption codes with five excitations at 360, 400, 420, 450, and 470 nm as the inputs, and the emission colors were used for information decoding. Thus, we determined why red emission was difficult to realize for Cdots, and our results could motivate the design of red-emission Cdots for extensive applications.

Fast radio bursts (FRBs) are recently discovered mysterious single pulses of radio emission, mostly coming from cosmological distances (∼1 Gpc). Their short duration, ∼1 ms, and large luminosity demonstrate coherent emission. I review the basic physics of coherent emission mechanisms proposed for FRBs. In particular, I discuss the curvature emission of bunches, the synchrotron maser, and the emission of radio waves by variable currents during magnetic reconnection. Special attention is paid to magnetar flares as the most promising sources of FRBs. Non-linear effects are outlined that could place bounds on the power of the outgoing radiation.

Radio observations from normal pulsars indicate that the coherent radio emission is excited by curvature radiation from charge bunches. In this review, we provide a systematic description of the various observational constraints on the radio emission mechanism. We have discussed the presence of highly polarized time samples where the polarization position angle follow two orthogonal well-defined tracks across the profile that closely match the rotating vector model in an identical manner. The observations also show the presence of circular polarization, with both the right and left handed circular polarization seen across the profile. Other constraints on the emission mechanism are provided by the detailed measurements of the spectral index variation across the profile window, where the central part of the profile, corresponding to the core component, has a steeper spectrum than the surrounding cones. Finally, the detailed measurements of the subpulse drifting behaviour can be explained by considering the presence of non-dipolar field on the stellar surface and the formation of the partially screened gap (PSG) above the polar cap region. The PSG gives rise to a non-stationary plasma flow that has a multi-component nature, consisting of highly energetic primary particles, secondary pair plasma, and iron ions discharged from the surface, with large fragmentation resulting in dense plasma clouds and lower-density inter-cloud regions. The physical properties of the outflowing plasma and the observational constraints lead us to consider coherent curvature radiation as the most viable explanation for the emission mechanism in normal pulsars, where propagation effects due to adiabatic walking and refraction are largely inconsequential.

Jellyfish stings, as one of the most prevalent forms of marine injury, have increasingly become a subject of concern. Despite their simple morphology and structure, jellyfish possess a complex venom composition that can inflict varying degrees of damage on multiple human physiological systems. Consequently, the clinical symptoms associated with jellyfish stings are highly intricate. Although antivenoms have been developed for certain jellyfish species (e.g., C. fleckeri), specific antivenoms targeting the mechanisms of most jellyfish venoms remain understudied. To effectively prevent, treat, and cure jellyfish stings, we adhere to the principle of knowing their nature and their reasons. It is essential to investigate the emission mechanism of jellyfish nematocysts and the composition of their venom. Understanding these factors is crucial for the development of targeted treatment strategies. This review delves into the venom emission mechanism of jellyfish stinging cells, the symptoms resulting from jellyfish stings, and the comprehensive treatment strategies post-sting. It offers a scientific reference for comprehending jellyfish stings and establishes a theoretical foundation for subsequent research endeavors.

To reduce volatile organic compounds (VOCs) emissions from rubber powder/SBS modified asphalt under high temperatures, the key road performance characteristics of asphalt modified with different proportions of rubber powder/SBS were investigated. The optimal rubber powder proportion was determined. The VOCs emission behavior of rubber powder/SBS modified asphalt before and after desulfurization was compared and analyzed using headspace gas chromatography–mass spectrometry (GC-MS). The VOCs emission mechanisms were revealed through microstructural testing. The results showed that the rubber powder/SBS modified asphalt exhibited good road performance with the optimal rubber powder content of 15%. As more rubber powder was added, the total VOCs emissions increased. Desulfurized rubber powder/SBS modified asphalt demonstrated superior performance in controlling harmful VOCs emissions. Undesulfurized rubber powder/SBS modified asphalt released more complex and toxic components compared to desulfurized rubber powder/SBS modified asphalt. The content of xylene was significantly higher than desulfurized rubber powder. Infrared spectroscopy analysis further validated the GC-MS results. Consistency in functional group changes was shown by both methods. Scanning electron microscopy revealed that the original cross-linked network of the adhesive powder was disrupted by desulfurization treatment. Interfacial activity and dispersion of the particles were enhanced. This led to the establishment of a more stable structural system and a reduction in VOCs emissions. Therefore, road performance was ensured, and VOCs emissions were significantly reduced by desulfurized rubber powder/SBS modified asphalt. This expands the utilization rate of waste rubber powder and reduces its environmental pollution.

The study of aggregation-induced emission luminogens (AIEgens) shows promising perspectives explored in lighting, optical sensors, and biological therapies. Due to their unique feature of intense emissions in aggregated solid states, it smoothly circumvents the weaknesses in fluorescent dyes, which include aggregation-caused quenching of emission and poor photobleaching character. However, our present knowledge of the AIE phenomena still cannot comprehensively explain the mechanism behind the substantially enhanced emission in their aggregated solid states. Herein, to systematically study the mechanism, the typical AIEgens tetraphenylethene (TPE) was chosen, to elucidate its photophysical properties, the TPE in THF/H2O binary solvents, TPE in THF solvents depending on concentration, and the following direct conversion from a dissolved state to a precipitated solid state were analyzed. Moreover, the TPE derivatives were also investigated to supply more evidence to better decipher the generally optical behaviors of TPE and its derivatives. For instance, the TPE derivative was homogeneously dispersed into tetraethyl orthosilicate to monitor the variance of photophysical properties during sol–gel processing. Consequently, TPE and its derivatives are hypothesized to abide by the anti-Kasha rule in dissolved states. In addition, the factors primarily influencing the nonlinear emission shifting of TPE and its derivatives are also discussed.

The correlations involving the long-gamma-ray bursts (GRBs) prompt emission energy represent a new key to understand the GRB physics. These correlations have been proved to be the tool that makes long-GRBs a new class of standard candles. Gamma Ray Bursts, being very powerful cosmological sources detected in the hard X-ray band, represent a new tool to investigate the Universe in a redshift range, which is complementary to that covered by other cosmological probes (SNIa and CMB). A review of the , , and correlations is presented. Open issues related to these correlations (e.g. presence of outliers and selection effects) and to their use for cosmographic purposes (e.g. dependence on model assumptions) are discussed. Finally, the relevance of thermal components in GRB spectra is discussed in the light of some of the models recently proposed for the interpretation of the spectral-energy correlations.

In recent years, due to governmental legislation, environmental groups’ pressures, customer green expectation, etc., closed-loop green supply chains have gained paramount consideration. Accordingly, this study develops a novel multi-objective mixed integer nonlinear programming model for a closed-loop green supply chain network design problem. The proposed model aims to minimize the total costs, total CO 2 emissions, and robustness costs in both forward and reverse directions, simultaneously. To cope with flexible constraints and epistemic uncertainty in the model’s parameters, a robust flexible-possibilistic programming approach is tailored. The model is solved using an efficient interactive solution approach, in which, the presented model is analyzed under various carbon emission mechanisms to assess the influence of these mechanisms on the achieved solution. An illustrative example in the copier industry is also provided to validate the applicability of the presented optimization model. Numerical results indicate the superiority of the carbon cap-and-trade policy in most of the cases.

Road asphalt produces hazardous substances that pollute the environment and significantly endanger human health. To clarify complex emission characteristics of these asphalt hazardous substances (AHS), their main components of AHS were comprehensively investigated and summarized. Furthermore, the emission rules of AHS under different testing conditions were systematically studied. To quantify these dynamics, robust regression models between AHS emissions and various experimental variable were successfully established. The analytical results demonstrated that the fundamental components of AHS mainly include volatile organic compounds, inorganic small molecule gases, and solid particles. Regarding thermodynamic variables, AHS emissions exhibit a marked increase as heating temperatures elevate. This specific dynamic conforms accurately to a power function relationship, yielding a strong correlation coefficient of 0.98. Conversely, AHS emissions progressively decrease with increasing heating times; this relationship conforms to an exponential function, demonstrating a correlation coefficient of 0.90. Additionally, the increased multiples of AHS emissions and asphalt qualities conform to a positive linear functional relationship, supported by a correlation coefficient of 0.96. A comparative analysis revealed that AHS emissions originating from rubber powder-modified asphalt are the highest. In stark contrast, AHS emissions from styrene- butadiene-styrene asphalt are notably the lowest when compared directly to the other three types of commonly used road asphalt. The emitted asphalt hazardous gases generate secondary inorganic salts and secondary aerosols, which actively promote the subsequent formation of fine particulate matter within these highly complex aerosol systems.