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The growing popularity of e-cigarettes and the associated risks of nicotine addiction present a new challenge to global public health security. Measuring the nicotine levels in e-cigarette aerosols is essential to assess the safety of e-cigarettes. In this study, a rapid in situmethod was developed for online quantification of nicotine in e-cigarette aerosols by using a homemade vacuum ultraviolet photoionization aerosol mass spectrometer (VUV-AMS). E-cigarette liquids with different nicotine concentrations were prepared to generate aerosols containing different levels of nicotine, which were employed as the calibration sources for nicotine quantification by VUV-AMS. The results showed that the mass concentration of nicotine in e-cigarette aerosols has a good linear relationship with its signal intensity in the mass spectrum, and the limits of detection and quantitation of nicotine by VUV-AMS were found to be 2.0 and 6.2 μg per puff respectively. Then the online method was utilized to measure five commercial e-cigarettes, and their nicotine yields were determined to be between 31 and 188 μg per puff with the nicotine fluxes from 7.7 to 70 μg s−1, agreeing with the results of the gas chromatography with a flame ionization detector (GC-FID). This study demonstrated the feasibility and advantages of VUV-AMS for quick quantification of nicotine in e-cigarette aerosols within seconds.

Covert communication offers a method to transmit messages in such a way that the communication is undetected. Yet, unconditional secure covert communication has not yet been achieved. In this work, we report an experimental demonstration of covert communication that is provably secure against quantum adversaries. We deploy the protocol in a dense wavelength-division multiplexing infrastructure, where our system coexists with a co-propagating C-band classical channel over 10 km of optical fiber. The noise from the classical channel, generally a negative factor in quantum communication, allows us to perform covert quantum communication in a neighboring channel. We report the transmission of three different messages with varying levels of security. Our results demonstrate the feasibility of secure covert communication in a practical setting, which shall find immediate application in optical communication.

Magnesium alloys are widely used as biodegradable medical biomaterials due to their density and modulus of elasticity close to that of human bone. However, too rapid degradation in the physiological environment limits their application. In this paper, the non-toxic and easy alloying properties of liquid metal gallium are utilized to make it a coating material for biomedical Mg–Nd alloys, which is used to solve the problem of the rapid degradation rate of Mg alloys. The corrosion resistance of the Ga–Mg alloy layer was investigated by in vitro immersion in simulated body fluid (SBF) and electrochemical experiments, and a microhardness tester characterized the surface hardness. In addition, the phase transformation of the Ga–Mg alloy layer was systematically investigated in combination with XRD diffraction results. The results showed that by adjusting the alloying time of Ga with Mg–Nd in liquid metal, a “retarded layer” with high hardness, stability, and good corrosion resistance was obtained. This study is expected to expand the application of Mg alloy materials in medicine.

With the advancement of gas power generation technology, the coupling relationship of the electricity and gas system is gradually increasing. Gas thermodynamics is an important mechanism in the process of gas transport, which has not been fully studied in the scheduling of hybrid power and gas systems (HPGS). Moreover, considering the N-1 contingency in HPGS operation can make systems robust to defend the single transmission line and pipe contingency. This paper establishes a novel optimal scheduling of HPGS considering N-1 contingencies and gas thermodynamics to promote the system reliability as well as model accuracy. The partial differential equation (PDE) depicting the heat power loss is established to model the temperature change, which effectively avoids the mathematical complexity of traditional pipeline thermal model. The finite difference scheme is utilized to discretize the PDE, thereby establishing an algebraic pipe model considering gas thermodynamics. The big-M approach is applied to integrate the N-1 criterion of both power and gas systems into the model of HPGS. Finally, the optimal scheduling of HPGS considering N-1 contingencies and gas thermodynamics can be obtained by coupling the power and gas network model. Case study validates the superiority of the proposed optimal scheduling model of HPGS with respect to model accuracy and system reliability.

Niobium nitride (NbN) is an important material for superconducting electronics because of its relatively high transition temperature in comparison to other conventional superconductors. Recent advances in the use of gas field focused ion beams for material modification motivate directly written NbN electronics. In this work, we study the electrical transport properties of ultra-thin film NbN microbridges irradiated with a focused helium ion beam. Twenty 4-$\mu$m wide strips were structured into an NbN thin film and irradiated with a helium ion microscope with ion fluences ranging from $1 \times 10^{18}$ He$^+/$cm$^{2}$ to $3 \times 10^{18}$ He$^+/$cm$^{2}$. We report the temperature and magnetic field dependence of the transport properties. At a higher dose of $1 \times 10^{20}$ He$^+$, the irradiation reduces the critical temperature of a narrow region resulting in a planar superconductor-reduced $T_{c}$ superconductor-superconductor (SS'S) Josephson junctions. This establishes that NbN can be modified in this manner for nanoelectronics, opening up possibilities for superconducting logic circuits and other higher-speed and high-temperature applications.

Atmospheric chemistry research has been growing rapidly in China in the last 25 years since the concept of the “air pollution complex” was first proposed by Professor Xiaoyan TANG in 1997. For papers published in 2021 on air pollution (only papers included in the Web of Science Core Collection database were considered), more than 24 000 papers were authored or co-authored by scientists working in China. In this paper, we review a limited number of representative and significant studies on atmospheric chemistry in China in the last few years, including studies on (1) sources and emission inventories, (2) atmospheric chemical processes, (3) interactions of air pollution with meteorology, weather and climate, (4) interactions between the biosphere and atmosphere, and (5) data assimilation. The intention was not to provide a complete review of all progress made in the last few years, but rather to serve as a starting point for learning more about atmospheric chemistry research in China. The advances reviewed in this paper have enabled a theoretical framework for the air pollution complex to be established, provided robust scientific support to highly successful air pollution control policies in China, and created great opportunities in education, training, and career development for many graduate students and young scientists. This paper further highlights that developing and low-income countries that are heavily affected by air pollution can benefit from these research advances, whilst at the same time acknowledging that many challenges and opportunities still remain in atmospheric chemistry research in China, to hopefully be addressed over the next few decades.

The regeneration of alveolar bone after tooth extraction is critical for the placement of dental implants. Developing a rigid porous scaffold with defect shape adaptability is of great importance but challenging for alveolar bone regeneration. Herein, we design and synthesize a biocompatible poly(l-glutamic acid)-g-poly(ε-caprolactone) (PLGA-g-PCL) porous shape memory (SM) polymer. The PLGA-g-PCL is then copolymerized with acryloyl chloride grafted poly(ω-pentadecalactone) (PPDLDA) having a higher phase transition temperature than shape recovery temperature to maintain stiffness after shape recovery to resist chewing force. The hybrid polydopamine/silver/hydroxyapatite (PDA/Ag/HA) is coated to the surface of (PLGA-g-PCL)-PPDL scaffold to afford the anti-bacterial activity. The porous SM scaffold can be deformed into a compact size and administered into the socket cavity in a minimally invasive mode, and recover its original shape with a high stiffness at body temperature, fitting well in the socket defect. The SM scaffold exhibits robust antibacterial activity against Staphylococcus aureus(S. aureus). The porous microstructure and cytocompatibility of PLGA allow for the ingrowth and proliferation of stem cells, thus facilitating osteogenic differentiation. The micro-CT and histological analyses demonstrate that the scaffold boosts efficient new bone regeneration in the socket of rabbit mandibular first premolar. This porous shape memory self-adaptive stiffened polymer opens up a new avenue for alveolar bone regeneration.

The appearance of mixed-metal MOF materials with abundant metal active sites, high porosity, large surface area, and, particularly, the synergistic effect between different metals which show prominent catalytic activity for oxygen evolution reaction (OER) has motivated profound research. Most of the related reports focus on the hydrothermal methods to prepare the mixed-metal MOFs containing metal ions such as Co, Ni, and Cr, etc. In this work, we proposed a facile impregnation method through an ion-exchange process to fabricate Fe-doped Co-BDC nanosheets (Fe@Co-BDC NSs) that represented significant enhancement for electrocatalytic OER. The tuning mechanism of the ion-exchange method was investigated by the morphology change and electronic structure of Fe@Co-BDC NSs, which should be important for an efficient OER catalyst. The optimized Fe@Co-BDC NSs (5 mM, 60 min) exhibited a significantly lower overpotential of 307 mV with a smaller Tafel slope of 34.1 mV·dec–1, as compared with the pure Co-BDC NSs.

Extracted-vanadium residue (EVR), formed during the smelting and extraction of High-chromium vanadium-titanium magnetite (HCVTM), should be used cyclically, and its use as a sintering material to prepare sinters for blast-furnace smelting is a viable option. The effects of EVR and MgO on the fundamental sintering characteristics of HCVTM, such as assimilative temperature, liquid phase fluidity index, adhesive phase strength, and crystal stock consolidation strength, were studied using X-ray diffraction and scanning electron microscopy, as well as phase composition analysis and microstructure analysis. The assimilative temperature (the lowest reaction temperature between sintering materials and CaO) of HCVTM by adding 0–8 wt% EVR decreased. The liquid phase fluidity index of HCVTM with six wt% EVR is best. The adhesive phase strength decreased from 1162 to 356 N. However, the crystal stock consolidation strength increased to the highest value of 2170 N by adding six wt% EVR. Based on the primary sintering characteristics effect of EVR on HCVTM, the optimum EVR amount is six wt%. After adopting the six wt% EVR added HCVTM with relatively good properties, the assimilative temperature of mixed ores increased from 1290 to 1320 °C with MgO added percent of 0–3 wt%. The liquid phase fluidity index decreased as a whole from 0.88 to 0.796–0.828, and the crystal stock consolidation strength also reduced from 2170 to 1090 N, indicating that both the liquid phase fluidity index and the crystal stock consolidation strength have changed slightly as a result of the addition of >1% MgO. However, adding 1% MgO improved the adhesive phase strength to a high value. The perovskite formation is restrained as Ti4+diffuses into the liquid phase with the increase of MgO. Based on the effect of the fundamental sintering characteristics of EVR and MgO on HCVTM, a sintering blending ratio of 6 wt% EVR and one wt% MgO is recommended.

Accurate and sensitive measurements of NO2play an extremely important role in atmospheric studies. Increasingly, studies require NO2measurements with parts per trillion by volume (pptv-level) detection limits. Other desirable instrument attributes include ease of use, long-term stability, and low maintenance. In this work, we report the development of an amplitude-modulated multimode-diode-laser-based cavity-enhanced absorption spectroscopy (AM-CEAS) system operating at 406 nm that uses phase-sensitive detection for extremely sensitive NO2detection. The laser was TTL-modulated at 35 kHz. The mirror reflectivity was determined to be 99.985% based on the ring-down time measurement. The cavity base length was 47.5 cm, giving an effective absorption pathlength of ∼3.26 km. AM-CEAS achieved a 1σ detection precision of 35 pptv in a 1 s data acquisition time (4.98 × 10–10cm–1), over 4 times lower than that attained using a ring-down approach and the same optical system. The AM-CEAS precision improved to 8 pptv over a data acquisition time of 30 s (1.14 × 10–10cm–1). The AM-CEAS method with the multimode diode laser integrates the advantages of high light injection efficiency like on-axis alignment cavity ring-down spectroscopy, low cavity-mode noise like off-axis alignment CEAS, and narrow-bandwidth high-sensitivity weak signal detection of modulation spectroscopy, providing a powerful, straightforward, and general method for ultrasensitive absorption and extinction measurements.

Knowledge of aerosol radiative effects in the Tibetan Plateau (TP) is limited due to the lack of reliable aerosol optical properties, especially the single scattering albedo (SSA). We firstly reported in situ measurement of SSA in Lhasa using a cavity enhanced albedometer (CEA) at λ= 532 nm from 22nd May to 11th June 2021. Unexpected strong aerosol absorbing ability was observed with an average SSA of 0.69. Based on spectral absorptions measured by Aethalometer (AE33), black carbon (BC) was found to be the dominated absorbing species, accounting for about 83% at λ= 370 nm, followed by primary and secondary brown carbon (BrCpriand BrCsec). The average direct aerosol radiative forcing at the top of atmosphere (DARFTOA) was 2.83 W/m2, indicating aerosol warming effect on the Earth‐atmosphere system. Even though aerosol loading is low, aerosol heating effect plays a significant role on TP warming due to strong absorbing ability. The Tibetan Plateau (TP) has experienced rapid warming over the past decades, but the key factors affecting TP climate change haven't yet been clearly understood. Aerosol single scattering albedo (SSA) is a key optical parameter determining aerosol warming or cooling effect; however, reliable SSA measurement is scarce in TP. This study firstly reported in situ measurement of SSA in Lhasa and explored the direct radiative effect of aerosol on TP warming. Strong aerosol absorption, mainly contributed by black carbon (BC), was observed with an average SSA value of 0.69 in this city. Besides Lhasa, other sites over TP were also reported with low SSA (≤0.77) from surface measurement. The strong aerosol absorption could cause heating effect on the Earth‐atmosphere system. To relieve TP warming, reasonable pollutant emission control strategies should be taken urgently to weaken aerosol absorbing ability. Unexpected low aerosol single scattering albedo was observed in Lhasa via in situ measurement of multiple optical parameters simultaneouslyBlack carbon was the dominant contributor (∼83%) to aerosol absorption at 370 nm, followed by primary and secondary brown carbonThe strong absorption in Lhasa exerted positive direct aerosol radiative forcing (warming effect) at the top of atmosphere Unexpected low aerosol single scattering albedo was observed in Lhasa via in situ measurement of multiple optical parameters simultaneously Black carbon was the dominant contributor (∼83%) to aerosol absorption at 370 nm, followed by primary and secondary brown carbon The strong absorption in Lhasa exerted positive direct aerosol radiative forcing (warming effect) at the top of atmosphere

Atmospheric simulation chambers play vital roles in the validation of chemical mechanisms and act as a bridge between field measurements and modeling. Chambers operating at atmospheric levels of OH radicals (106–107molecule/cm3) can significantly enhance the possibility for investigating the discrepancies between the observation and model predications. However, few chambers can directly detect chamber OH radicals at ambient levels. In this paper, we report on the first combination of a superconducting magnet with midinfrared Faraday rotation spectroscopy (FRS) for real time in situ measurement of the OH concentration in an atmospheric simulation chamber. With the use of a multipass enhanced FRS, a detection limit of 3.2 × 106OH/cm3(2s, 4s) was achieved with an absorption path length of 108 m. The developed FRS system provided a unique, self-calibrated analytical instrument for in situ direct measurement of chamber OH concentration.

Severe volume expansion will cause the gallium-based liquid metal cathode material to detach from the collector thus deteriorating performance. Here, we propose a strategy for preparing electrodes by anchoring the liquid metal with an intermetallic compound transition phase to avoid the problem of liquid metal shedding during cycling. The good reactive wetting between the CuGa2transition phase and gallium can firmly anchor the liquid metal to prevent the electrode material exfoliating from the collector. On the other hand, the unique two-dimensional layer structure of CuGa2can also limit the lithiation volume expansion of liquid gallium. Density functional theory (DFT) reveals the anchoring mechanism of the CuGa2transition layer to liquid gallium and the reaction mechanism of Li with CuGa2during the electrochemical reaction. As a result, O-GaSn/CF cathodes exhibit low resistance, fast ion diffusion, high reversible capacity, excellent rate performance and outstanding cycling stability.

Sunlight may lead to changes in disinfection byproducts (DBPs) formation potentials of source water via transforming dissolved organic matter (DOM); however, the underlying mechanisms behind these changes remain unclear. This work systematically investigated the effect of photochemical transformation of DOM from reservoir water (DOMRe) and micropolluted river water (DOMRi) after 36 h of simulated sunlight irradiation (equivalent to one month under natural sunlight) on DBPs formation. Upon irradiation, high molecular weight (MW) and aromatic molecules tended to be mineralized or converted into low-MW and highly oxidized (O/C > 0.5) ones which might react with chlorine to generate high levels of DBPs, resulting in an elevation in the yields (μg DBP/mg C) of almost all the measured DBPs and the quantities of unknown DBPs in both DOM samples after chlorination. Additionally, DOMRicontained more aromatic molecules susceptible to photooxidation than DOMRe. Consequently, irradiated DOMRiexhibited a greater increase in the formation potentials of haloacetonitriles, halonitromethanes, and specific regulated DBPs, with nitrogenous DBPs being responsible for the overall rise in the calculated cytotoxicity following chlorination. This work emphasized the importance of a comprehensive removal of phototransformation products that may serve as DBPs precursors from source waters, especially from micropolluted source waters.

In this work, the calcined chitosan (CS)-supported layered double hydroxides were prepared, characterized, and further applied to remove organic contaminants in aqueous solution. The chitosan-supported layered double hydroxide calcined at 400 °C (CSLDO400) was found to be effective for the adsorption of azo dye and antibiotic. CSLDO400 showed excellent adsorption performance at a wide pH range from 5 to 9 for methyl orange (MO) while the adsorption of tetracycline (TC) was most efficient at a pH of 9, and the optimal CSLDO400 dosages were 0.175 g L–1for MO and 0.375 g L–1for TC. The divalent and trivalent anions have a great effect on removal efficiency of MO and TC, while the effect of monovalent anions adsorption can be neglected. The adsorption kinetics indicated that the MO and TC removal followed the pseudo-second-order model. In addition, it can be fitted well with both the Langmuir and Freundlich model for MO and TC at 298 K, respectively. The adsorptions of MO and TC on CSLDO400 were both spontaneous and endothermic. After five adsorption–desorption cycles, CSLDO400 still showed high efficiency with an adsorption capacity of 60.72 mg g–1for MO and 21.92 mg g–1for TC. Therefore, the CSLDO400 are promising for use in the treatment of drinking water and wastewater contaminanted by organic matters.

For battery thermal management, the phase change material (PCM) has demonstrated its advantages as a thermal buffer. In this paper, we proposed a novel thermal regulator that intelligently utilizes the volume changes to modulate heat transfer. The thermal regulator establishes a passive and negative feedback mechanism between the PCM and the cooling system, enabling a consistent and optimal operating battery temperature. This innovation negates the need for sensors or external logic devices, using a resilient valve passively adjusted by PCM volume changes. This in turn modulates coolant flow rate and battery temperature. Its thermal management performance is compared to other configurations like natural cooling, pure PCM, and composite PCM (cPCM). Extended dynamic tests are conducted at different ambient temperatures (Tamb) for evaluation. The results indicate that batteries without thermal regulators fail to operate when Tambexceeds 30 °C. At Tamb = 35 °C, the thermal regulator with cPCM exhibits repeated switching and effectively keeps the battery temperature lower than 38.13 °C. At Tamb > 40 °C, both thermal regulators active to achieve faster heat dissipation. At 45 °C, the thermal regulator with cPCM successfully reduces the battery temperature to 35.02 °C. Integrating AlN in pure PCM lowers the battery module's peak temperature by 7.94 %. The thermal regulator also diminishes cyclic temperature variances, underlining its potential for enhancing battery thermal management.

Carbon dioxide (CO2) adsorption is a critical step to curbing carbon emissions from fossil fuel combustion. Among various options, transition metal oxides have received extensive attention as promising CO2adsorbents due to their affordability and sustainability for large-scale use. Here, the nature of binding interactions between CO2molecules and cationic scandium oxides of different sizes, i.e., ScO+, Sc2O2+, and Sc3O4+, is investigated by mass-selective infrared photodissociation spectroscopy combined with quantum chemical calculations. The well-accepted electrostatic considerations failed to provide explanations for the trend in the binding strengths and variations in the binding orientations between CO2and metal sites of cationic scandium oxides. The importance of orbital interactions in the driving forces for CO2adsorption on cationic scandium oxides was revealed by energy decomposition analyses. A molecular surface property, known as the local electron attachment energy, is introduced to elucidate the binding affinity and orientation-specific reactivity of cationic scandium oxides upon the CO2attachment. This study not only reveals the governing factor in the binding behaviors of CO2adsorption on cationic scandium oxides but also serves as an archetype for predicting and rationalizing favorable binding sites and orientations in extended surface–adsorbate systems.

A universal and efficient magnetron sputtering modification strategy has been proposed to prepare LiCoO2@Li3PO4cathodic composites to effectively solve the challenges of rapid capacity decay and electrode crushing of LiCoO2cathodes.

The dielectric composites which are consisted of polymer matrix and ceramic fillers recently spark tremendous research interest as the promising energy storage materials in dielectric capacitors. However, the poor compatibility and huge dielectric mismatch between inorganic ceramic and organic polymer inevitably induce the severe aggregation and local free charge carriers accumulation at the interface, thus deteriorating the breakdown strength and energy storage performance. Herein, a novel plum pudding structured BaTiO3@ZIF-67 filler is designed and prepared for the first time, where numerous BaTiO3nanoparticles are distributed uniformly within the ZIF-67, therefore effectively alleviating the aggregation phenomenon. Employing P(VDF-HFP) as the polymer matrix, BaTiO3@ZIF-67/P(VDF-HFP) composites with various filler loadings are fabricated. Notably, the composite with 3 wt% filling ratio presents the maximum discharge energy density of 12.8 J/cm3, which is much higher than that of the pristine P(VDF-HFP) and the counterpart filled with the same loading uncoated BaTiO3nanoparticles. The improvement of the energy storage performance is mainly attributed to the increase of breakdown strength after introducing the ZIF-67 interlayer, and the enhancement mechanism is further revealed by finite element analysis method. This work provides an intriguing strategy of the filler structure modulation for achieving high-performance composite dielectrics.

The ZnO composite photocatalyst has recently been an effective tool for the removal of organic pollutants during water treatment. However, it is still a great challenge to fabricate cost-effective ZnO composite photocatalyst with high photocatalytic efficiency. This study presents the synthesis of the composites, biochar-supported ZnO nanoparticles, by adjusting the molar ratio of biochar/ZnO with hydrothermal method. The composite, biochar-supported 3D flower-shaped ZnO nanoparticles with a preferred crystal plane (002), exhibited the excellent degradation efficiency of methylene blue (MB) under UV–visible light when the molar ratio of biochar/ZnO is 1:0.5. The chemical bond Zn–O–C formed at the interface between the biochar and ZnO nanoparticles, and this facilitates a lower recombination rate of the e−/h+pairs originated from the stimulation of ZnO nanoparticles, which was also supported by the results of transient photocurrent response and the electrochemical impedance spectroscopy (EIS). The synergetic effect of biochar and ZnO consequently lead to the higher degradation efficiency of the composite than that of pure ZnO. Moreover, trapping experiments further confirmed the contribution of the active radicals (h+, •O2-, OH•) in the degradation of MB. In addition, the essential role of porous biochar with a high specific surface in the cooperatively catalytic mechanism was also discussed in detail. This research offers a revealing insight into the design and fabrication of ZnO photocatalysts that applied in the purification and remedy of environment.

In this work, the humic acid (HA)-modified g-C3N4-supported hydrotalcite-like compounds (g-C3N4@HTLcs/HA) was successfully synthesized, characterized, and further applied to remove 2,4-dichlorophenol (DP), glyphosate (GH), and tetracycline (TL) from aqueous solution. The results showed that g-C3N4@HTLcs/HA had obvious layered structure, and a large amount of HA was successfully loaded on the surface. When HA concentration was 100 mg L–1, the adsorption capacity of DP, GH, and TL was relatively high. The optimal pH range of TL adsorption was 7–9 and that of DP and GH were 3–9, and the influence of ionic strength on the adsorption of g-C3N4@HTLcs/HA100 was limited. The isotherm experimental data of TL, GH, and DP adsorption onto g-C3N4@HTLcs/HA100 were best fitted by Freundlich and Langmuir models. The adsorption of TL, DP, and GH was all consonant with the pseudo-second-order kinetic model and spontaneous endothermic process. Based on the mass transfer theory, the diffusion of TL, DP, and GH on the adsorption process under liquid film control was derived. The adsorption mechanism might be the ion exchange between the layers of hydrotalcite, and the surface complexation and hydrogen bonding between various groups of HA and organic contaminants. This work suggested that g-C3N4@HTLcs/HA100 was effective in treatment of water containing various organic pollutants.

Quantum key distribution (QKD)1,2offers a long-term solution to secure key exchange. Due to photon loss in transmission, it was believed that the repeaterless key rate is bounded by a linear function of the transmittance, O(η) (refs. 3,4), limiting the maximal secure transmission distance5,6. Recently, a novel type of QKD scheme has been shown to beat the linear bound and achieve a key rate performance of O(η)(refs. 7–9). Here, by employing the laser injection technique and the phase post-compensation method, we match the modes of two independent lasers and overcome the phase fluctuation. As a result, the key rate surpasses the linear bound via 302 km and 402 km commercial-fibre channels, over four orders of magnitude higher than existing results5. Furthermore, our system yields a secret key rate of 0.118 bps with a 502 km ultralow-loss fibre. This new type of QKD pushes forward long-distance quantum communication for the future quantum internet.

Growing evidence indicates that organic aerosol (OA) is a significant absorber of solar radiation. Such absorptive OA is known as “brown carbon” (BrC). However, a formal analytical method for BrC is currently lacking although several methods have been applied to determine its absorption properties. Reported imaginary refractive index (kOA) values from various combustion sources span 2 orders of magnitude. Measurement methods are an important factor affecting this kOAvariation. In this work, isolated OA from wood pyrolysis was used to compare four methods to determine absorbing properties of OA. The generated aerosol was lognormally distributed, spherical, and nearly pure organic matter. Optical closure was considered as the reference method. kOAcalculated from the extract bulk light absorbance measurement was comparable to that determined by optical closure. kOAand mass absorption cross section obtained by online and offline filter-based transmission measurements were similar, but 3.5 to 5.0 times greater than those determined by optical closure. Absorption Ångström Exponents determined by the four methods were comparable and ranged from 6.1 to 6.8. A clear-sky radiative transfer model implied that using the optical parameters derived from different methods in the full climate model could produce different radiative impacts of primary OA emissions.

The total OH reactivity (kOH′) is an important parameter for quantitative assessment of the atmospheric oxidation capacity. Although laboratory measurement of kOH′ has been achieved 20 years ago, the instruments required are often costly and complex. Long-term atmospheric observations remain challenging and elusive. In this work, a novel instrument combining laser-flash photolysis with a mid-infrared Faraday rotation spectrometer (LFP-FRS) has been developed for the measurement of kOH′ and for studying gas phase free radical kinetics. The reactor is composed of a Herriott-type optical multipass cell, and OH radicals were generated by flash photolysis of ozone with a 266 nm pulsed Nd:YAG laser. The decay of the OH signal was directly measured with a time-resolved FRS spectrometer at 2.8 μm. The overlapping path length between the pump beam and probe beam was 25 m. High performance was achieved by subtracting the signals before and after flash photolysis to eliminate interferences caused by H2O absorption and background drift. The optimum precisions (1σ) of OH concentration and kOH′ measurement were 4 × 106molecules cm–3and 0.09 s–1over data acquisition times of 56 and 112 s, respectively. The performance of the system was evaluated by the reaction of OH with CO and NO. The measured rate coefficients (kOH+COand kOH+NO) were in good agreement with values reported in the literature. The developed LFP-FRS provides a new, high precision, and highly selective tool for atmospheric chemistry research of OH radicals and other transient paramagnetic free radicals such as HO2radicals.

The development of photonic quantum information technologies requires research on the properties of optical adhesives at cryogenic temperatures. In the process of developing microfiber (MF)-coupled superconducting nanowire single-photon detectors (SNSPDs), we invented a cryogenic-temperature refractive index (RI) measurement method based on a kind of MF device. The device was put into the cryostat to observe the variance of MF transmittance with temperature. Then an RI–temperature relationship was established through the correspondence between the confinement conditions of MFs of various diameters in an optical adhesive–${{\rm MgF}_2}$MgF_2 environment and transmittance–temperature curves. Using this method, we analyzed the thermal-optical properties of a commercial fluorinated acrylic optical adhesive and obtained the RI values of the adhesive at various temperatures. The results were successfully applied in the development of broadband and high-efficiency MF-coupled SNSPDs.

The protein corona has gained much attention in the field of nano-biomedicine and has expanded from applications in the biological field to the ecosphere. However, the bio-corona (extracellular protein corona) composed of nano-quantum dots (CdSe@ZnS) and extracellular proteins in an activated sludge system was limited by the inability to identify the composition and molecular structure of extracellular proteins. Herein, extracellular proteins (EP) were extracted from the active sludge (AS) system and purified by using a novel method (modified-ammonium sulfate precipitate) and then identified by proteomic technology. The interaction between nano-quantum dots and extracellular protein was investigated with multi-spectroscopic technology and microscopic analysis. The results revealed that 97 protein groups were detected and most of their molecular functions were related to the cation binding activity. The self-aggregation effect of protein particles and the formation of the bio-corona were observed. Meanwhile, α-helical structures of EPs in active sludge were converted into β-sheets conformation viaelectrostatic and hydrogen bonding processes, with the addition of nano-quantum dots, resulting in decreased fluorescence intensities for proteins. This finding not only provided a novel method for the purification of EP from extracellular polymeric substances, but also provided an insight into the interaction between NPs and actual EP in the AS system.

We report the development of an improved spherical mirror multipass-cell-based interband cascade laser (ICL) spectrometer for ambient formaldehyde (HCHO) detection. The multipass cell consists of two easily manufactured spherical mirrors that are low cost, and have a simple structure, large mirror area utilization, and dense spot pattern. Optical interference caused by the multipath cell was largely reduced, resulting in good sensitivity. Using wavelength modulation spectroscopy (WMS), a detection precision (${1} \sigma $1σ) of 51 pptv in 10 s was achieved with an absorption pathlength of 96 m, which compared favorably with the performance of other state-of-the-art instruments. The precision can be further improved by using a long absorption pathlength configuration and by removing fringe-like optical noise caused by the collimation lens. Ambient application of the developed spectrometer was demonstrated.

ABSTRACTMalodor is becoming the main secondary pollution in the municipal sewage sludge-composting process. Ammonia and volatile sulfide compounds (VSCs) are the representative odorants that generated and emitted during the composting process. The emission characteristics of ammonia and VSCs were studied at different workshops in a full-scale municipal sludge-composting plant in North People's Republic of China. Results show that ammonia was the most dominant odorant of all the workshops and relative high concentrations of VSCs were detected at sludge stacking yard and composting workshop. The odor pattern of VSCs at the composting workshop and stacking yard were different. The odor pollution occurred mainly in the first 15 days of the composting process, in which the odor contribution of ammonia increased with time and the VSCs contributed largely in the first 5 days. The cumulative release concentration of VSCs from compost materials was in the order of DMDS (dimethyl disulfide) > DMS (dimethyl sulfide) > CS2 > MT (methyl mercaptan), and the total VSCs release concentration was in the range of 50–3200 μg·m−3. The production of ammonia correlated to the temperature and nitrogen content and state changes, however, the production of VSCs was more complicated due to the reaction and transformation of VSCs. Optimization of aerobic composting conditions and process parameters should be further studied to reduce the emission of odor gas from compost.Implications:Along with the widespread use of sludge aerobic composting in People's Republic of China, the malodor pollution during the composting treatment is becoming a serious environmental issue. The odor pollution occurred mainly in the first 15 days, and ammonia was the main odorant of all the workshops and need to be controlled. Relative high concentrations of VSCs were detected at sludge stacking yard and composting workshop, however, the odor impact of VSCs were different. The generation of VSCs is more complicated than ammonia due to the reaction and transformation of VSCs.

In this work, we report a large-active-area multispectral superconducting nanowire single-photon detector for free-space applications. The detector is realized by fabricating NbTiN nanowire with an active area of 35 µm diameter on two serially connected dielectric mirrors that can simultaneously and efficiently detect single photons at the three typical wavelengths employed in free-space applications, namely, 532, 850, and 1064 nm. Maximal system detection efficiencies (SDEs) of 80.0% at 532 nm and 850 nm and 75.8% at 1064 nm are achieved for polarized light obtained by coupling the detector with an SMF-28 fiber. Upon coupling with a 50 µm multimode fiber, SDEs of 68.6%, 59.6%, and 47.0%, are achieved for 532, 850, and 1064 nm wavelength unpolarized light, respectively. Moreover, the detector shows timing jitters of 37.1 and 41.0 ps when coupled with SMF-28 fiber and 50 µm multimode fiber. This type of detector with a large active area and multiwavelength detection capability is promising for both single and multiwavelength free-space applications.

The ongoing interest in creating a secure global quantum network culminated recently in the demonstration of transcontinental quantum communication1. There is a pressing need to examine the properties attached to a quantum network architecture from multiple perspectives, including physics foundations2, communication security3, the efficient use of resources and innovative technological applications4,5. Here, we present an experimental realization of a five-node quantum network, in which quantum sources at two nodes deliver entangled photon pairs to three measurement nodes. With relevant events between five nodes separated space-like, we demonstrate violation of the Bell inequality and bilocal inequality6, with the locality, measurement independence and quantum source independence loopholes closed simultaneously in a quantum network. This experimental realization may be valuable for the design and implementation of future quantum networks.

Gallium oxide is one of the most promising anode materials for lithium‐ion batteries due to its high theoretical specific capacity and ability to maintain self‐healing behavior during the reaction process. However, the susceptibility to volume expansion during the alloying reaction, which affects cycling performance, and the unclear lithium storage mechanism limit the application of Ga2O3. For this purpose, α‐Ga2O3@ chitosan‐derived carbon nanocomposites (α‐Ga2O3@CS NPs) are synthesized by introducing biomass materials. Due to the capacity contribution of Ga2O3and the inhibition of biomass carbon on volume expansion, the composites exhibit excellent electrochemical performance. A high reversible capacity is shown in the long‐cycle test, with a discharge capacity of 505.1 mAh g−1after 130 cycles at 0.2 A g−1, with no significant decrease from the initial capacity. During the periodic rate performance test of 0.1–5 A g−1, the reversible discharge capacity of the electrode material is maintained at 482.2 mAh g−1when the current is restored to 0.1 A g−1. In addition, the lithium storage process of the electrode is investigated by in situ X‐ray diffraction, which, together with the low‐cost synthesis process, promotes the practical application prospect of Ga2O3. Lithium‐ion battery with α‐Ga2O3@CS nanoparticles (NPs) as anode is reported. Not only the self‐nitrogen doping of the material is realized, but also the volume expansion effect caused by the reaction process is effectively inhibited. In addition, the lithium storage process of α‐Ga2O3@CS NPs anode material is revealed by in situ X‐ray diffraction testing.

Fast and high efficiency single-photon detectors have important applications in the fields of life science and quantum information. We report, herein, a serially connected two superconducting nanowire avalanche photon detector (SC2-SNAP) fabricated on a dielectric mirror aiming to 630 nm wavelength. This detector shows system detection efficiency (SDE) of 84.8% at a dark count rate of 10 Hz and offers fast detection speed while maintaining a high SDE, where the counting rate reaches 53.9 MHz at an SDE of 60%. This fast and high efficiency single-photon detector may find applications in fluorescence correlation spectroscopy and quantum key distribution.

In our previous work (Yang et al. Anal. Chem.2018, 90(5), 3307−3312), we reported that a large diameter Nafion dryer can be used in the PERCA (PEroxy Radical Chemical Amplification) technique to minimize the impact of water vapor on the chain length (CL). By using a Nafion dryer, the sample was first dried to a low relative humidity (RH) and was then drawn into a FEP (fluorinated ethylene propylene) flow reactor tube to start the amplification cycles for peroxy radical measurement. This method provides a promising and simple method to minimize the sensitivity of CL to water vapor. However, there is a trade-off between inlet radical losses and moisture removal efficiency under high ambient RH conditions. In this paper, we report a further improvement by removing the inlet Nafion dryer and using it directly as an amplifier. The sample was drawn into the Nafion dryer directly without preconditioning to reduce inlet losses; the amplification and HO2reformation cycles were started in the Nafion dryer. The CL value at 3% RHinletwas about 150. A linear relationship between CL and RHinletup to 87% RH was observed. Low loss of the CL under high RHinlet(about 10% reduction at 87% RH) was achieved. As a result, the modified system can largely remove the uncertainty of the CL arising from water vapor under most ambient conditions.

Randomness is important for many information processing applications, including numerical modelling and cryptography1,2. Device-independent quantum random-number generation (DIQRNG)3,4based on the loophole-free violation of a Bell inequality produces genuine, unpredictable randomness without requiring any assumptions about the inner workings of the devices, and is therefore an ultimate goal in the field of quantum information science5–7. Previously reported experimental demonstrations of DIQRNG8,9were not provably secure against the most general adversaries or did not close the ‘locality’ loophole of the Bell test. Here we present DIQRNG that is secure against quantum and classical adversaries10–12. We use state-of-the-art quantum optical technology to create, modulate and detect entangled photon pairs, achieving an efficiency of more than 78 per cent from creation to detection at a distance of about 200 metres that greatly exceeds the threshold for closing the ‘detection’ loophole of the Bell test. By independently and randomly choosing the base settings for measuring the entangled photon pairs and by ensuring space-like separation between the measurement events, we also satisfy the no-signalling condition and close the ‘locality’ loophole of the Bell test, thus enabling the realization of the loophole-free violation of a Bell inequality. This, along with a high-voltage, high-repetition-rate Pockels cell modulation set-up, allows us to accumulate sufficient data in the experimental time to extract genuine quantum randomness that is secure against the most general adversaries. By applying a large (137.90 gigabits × 62.469 megabits) Toeplitz-matrix hashing technique, we obtain 6.2469 × 107quantum-certified random bits in 96 hours with a total failure probability (of producing a random number that is not guaranteed to be perfectly secure) of less than 10−5. Our demonstration is a crucial step towards transforming DIQRNG from a concept to a key aspect of practical applications that require high levels of security and thus genuine randomness7. Our work may also help to improve our understanding of the origin of randomness from a fundamental perspective.