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In this study, a highly efficient peroxymonosulfate (PMS) activator, ZnO/ZnMn2O4, was synthesized using a simple one‐step hydrothermal method. The resulting bimetallic oxide catalyst demonstrated a homogenous and high‐purity composition, showcasing synergistic catalytic activity in activating PMS for degrading 2, 4‐dichlorophenol (2, 4‐DCP) in aqueous solution. This catalytic performance surpassed that of individual ZnO, Mn2O3, and ZnMn2O4 metal materials. Under the optimized conditions, the removal efficiency of 2, 4‐DCP reached approximately 86% within 60 min, and the catalytic ability remained almost constant even after four cycles of recycling. The developed degradation system proved effective in degrading other azo‐dye pollutants. Certain inorganic anions such as HPO4−, HCO3−, and NO3− significantly inhibited the degradation of 2, 4‐DCP, while Cl− and SO42− did not exhibit such interference. Results from electrochemical experiments indicated that the electron transfer ability of ZnO/ZnMn2O4 surpassed that of individual metals, and electron transfer occurred between ZnO/ZnMn2O4 and the oxidant. The primary active radicals responsible for degrading 2, 4‐DCP were identified as SO4•−, OH• and O2•−, generated through the oxidation and reduction of PMS catalyzed by Zn (II) and Mn (III). Furthermore, X‐ray photoelectron spectroscopy (XPS) analysis of the fresh and used catalysts revealed that the exceptional electron transfer ability of ZnO facilitated the valence transfer of Mn (III) and the transfer of electrons to the catalyst's oxygen surface, thus enhancing the catalytic efficiency. The analysis of radicals and intermediates indicates that the two main pathways for degrading 2, 4‐DCP involve hydroxylation and radical attack on its aromatic ring. Practitioner Points: A bimetallic ZnO/ZnMn2O4 catalyst was synthesized and characterized.ZnO/ZnMn2O4 can synergistically activate PMS to degrade 2, 4‐DCP compared with single metal oxide.Three primary active radicals, O2•−, •OH, and SO4•−, were generated to promote the degradation.ZnO promoted electron transfer among the three species of Mn to facilitate oxidizing pollutants.Hydroxylation and radical attack on the aromatic ring of 2, 4‐DCP are the two degradation pathways. [ABSTRACT FROM AUTHOR]

Quantum teleportation is one of the fundamental primitives of quantum cryptography. In order to achieve a wider range of high-capacity information transfer, we propose a free-space quantum teleportation (QT) protocol with orbital angular momentum (OAM) multiplexed continuous variable (CV) entangled states. The preparation of the entangled states is accomplished by the spontaneous four-wave mixing (SFWM) process occurring in a hot 85 Rb vapor cell, and the mode selection for the Bell-state measurement is achieved by employing the balanced homodyne detection technique. The fidelity of teleporting EPR entangled states carrying different topological charges via a Kolmogorov-type atmospheric turbulence channel is derived, and the superiority of enhancing the system channel capacity via OAM multiplexing is demonstrated. Our work provides a feasible scheme to implement high-capacity quantum communication in atmospheric environments. [ABSTRACT FROM AUTHOR]

Frequency entangled state originated from optical frequency comb (OFC) is an important quantum source for quantum communication. In this paper, we propose a traveling quantum anonymous voting (TQAV) protocol, which employs a monolithic microresonator with cascaded four-wave mixing (FWM) to prepare continuous-variable frequency entanglement sources. Multi-pair EPR entangled states and five-partite entangled states generated from the degenerate and nondegenerate FWM process are used as signal sources for the TQAV to characterize different candidates. Voters are able to vote for their preferred candidates by performing displacement operations on the received modes, and the ballot agency can judge the voting result according to the measurements. The entanglement property of the quantum state is utilized to keep voters away from the voting results. The security of the protocol under collective attacks and spectroscopic noise attacks is guaranteed by the security mechanism of continuous-variable quantum key distribution. Our results provide a reference for the application of OFC in multiparty quantum communication. [ABSTRACT FROM AUTHOR]

Passive continuous variable quantum key distribution using multimode thermal source waives the necessity of usage of amplitude and phase modulators, thus it can effectively simplify the implementation of quantum key distribution. Compared with Gaussian modulation quantum key distribution scheme, this protocol is more cost-effective. However, the composable security of this scheme under collective attack has not been proved. In view of this, we take the composable security of the protocol under collective attack into consideration, and analyze the impact of the average photon number and mode-overlap coefficient on the performance of passive continuous variable quantum key distribution using multimode thermal source. In order to make comparison, we also calculate the asymptotic secret key rate of the passive continuous variable quantum key distribution protocol using multimode thermal source. Simulation results show that the composable secret key rate of this protocol is always lower than its asymptotic secret key rate. When the number of exchanged optical pulse signals is large enough, the composable secret key rate of the protocol approaches the asymptotic secret key rate. In addition, the composable secret key rate of this scheme can be further improved with the increase of average output photon number and mode-overlap coefficient. [ABSTRACT FROM AUTHOR]

Quantum digital signature (QDS) ensures the integrity of a classical message and the authenticity of its sender based on information-theoretical limits and quantum mechanical mechanisms. The existing polarization-encoded or phase-encoded QDS protocols are susceptible to the interference from non-ideal factors in the quantum channel, resulting in the mismatch of the measurement reference frame. The channel capacities of these protocols are also limited, reducing the practicability of these protocols. To overcome these defects, we present a time-bin orbital angular momentum (OAM)-encoded continuous variable QDS (CVQDS) protocol, which exploits the rotation invariance of the vortex beam in the transmission direction to circumvent the real-time calibration of the reference frame and utilizes the infinite-dimensional eigenstate characteristics of the OAM states to beat the channel capacity limit. Security analysis and numerical simulations show that it is feasible to use this protocol to sign 1-bit message in atmospheric channel, and the channel capacity can be improved by increasing the dimensionality of the OAM code. [ABSTRACT FROM AUTHOR]

Unidimensional continuous-variable quantum key distribution (CV-QKD) protocol with Gaussian modulation is simpler in implementation and lower in costs than its two-dimensional counterpart, but its secure transmission distance is not as far as the latter. In this paper, we give a solution that using the photon subtraction, which is one of non-Gaussian operations, to improve the performance of the unidimensional CV-QKD protocol. Security analysis and numerical simulation indicate that the photon subtraction operation can significantly improve the secure transmission distance of the unidimensional CV-QKD protocol. [ABSTRACT FROM AUTHOR]

Silver-based materials have emerged as excellent catalysts for peroxymonosulfate (PMS) activation in wastewater pollutants degradation. However, the mechanism of pure silver oxides towards PMS activation remains insufficient. In this work, Ag 2 O and AgO were selected as typical silver oxides to detect the catalytic performance. AgO/PMS possessed higher activity for p-nitrophenol and other pollutants degradation than Ag 2 O/PMS. The stability experiment and structure changes characterized from XRD, FTIR, and XPS, as well as quenching research, demonstrated that SO 4 •− was the main free radical produced from the oxidation of Ag(I) to Ag(II) and reduction of Ag(II) to Ag(I) by PMS; meanwhile, the high valence Ag(II) could directly oxidize the pollutants, which was also contributable to the degradation. Compared with Ag 2 O, AgO exhibited better efficiency and recyclability. These results provide key mechanistic insights into silver oxides towards PMS activation. [Display omitted] • Silver based oxides Ag 2 O and AgO was used for PMS activation. • The two catalysts showed similar performance for PNP degradation. • The reusability and stability of AgO was much better than that of Ag 2 O. • SO 4 •− radicals were produced from the oxidation of Ag(I) by PMS. • The high active Ag(II) species contributed to the degradation process. [ABSTRACT FROM AUTHOR]

Engineered nanomaterials (ENMs) can be released to the environment during their lifecycles. The potential uptake by biological systems, along with uncertain distribution pathways, makes this class of materials important to study from a perspective of potential impacts to the environment and people. In this study, colloidal quantum dots (Q-dots), with diameter around 3 nm and passivated with CH chains (oleic acid), were used, as a model system, to investigate the fate and the transformations of ENMs under UV irradiation in the presence of air. Before and after the UV light irradiation, the changes of the Q-dots on DNA interaction potency, and UV-Vis and fluorescence spectra are compared. When the Q-dots were exposed to UV light, the formation of water-soluble products was confirmed by UV-Vis and fluorescence spectra collected from aqueous dispersions and by the mass loss. Both the UV irradiation time and intensity were found to influence the amount of water-soluble products produced. However, before and after UV irradiation, the Q-dots exhibited little change of their DNA interaction potency. Therefore, it seems that the Q-dot surface chemical reactivity to DNA changed little, in conjunction with photo-oxidization of the surface passivation ligand. [ABSTRACT FROM AUTHOR]

Abstract: A simple cerium salt Ce(NO3)3 was used as the catalyst for alizarin green (AG) degradation under UV irradiation. It was found that the anthraquinone dye can be completely removed by the system. The photodegradation reaction mainly involved the participation of hydroxyl radical, which was generated by the oxidation of Ce(III) ions to Ce(IV); while the Ce(IV) ion itself could only decolorize the dye with a relatively slow rate. Several intermediate products were detected by electrospray ionization mass spectrometry and a possible pathway was proposed. Many other organic dyes and phenol could also be efficiently degraded by the system. [Copyright &y& Elsevier]

The secret key rate is one of the main obstacles to the practical application of continuous-variable quantum key distribution (CVQKD). In this paper, we propose a multiplexing scheme to increase the secret key rate of the CVQKD system with orbital angular momentum (OAM). The propagation characteristics of a typical vortex beam, involving the Laguerre–Gaussian (LG) beam, are analyzed in an atmospheric channel for the Kolmogorov turbulence model. Discrete modulation is utilized to extend the maximal transmission distance. We show the effect of the transmittance of the beam over the turbulent channel on the secret key rate and the transmission distance. Numerical simulations indicate that the OAM multiplexing scheme can improve the performance of the CVQKD system and hence has potential use for practical high-rate quantum communications. [ABSTRACT FROM AUTHOR]

Factors affecting the degradation of Acid Orange 7 (AO7) were evaluated and optimized when ferrous was used to catalyze percarbonate in the present study. The optimized conditions included the initial pH values ranging from 3 to 11 for AO7 solution, the initial level of AO7, sodium percarbonate (SPC), and Fe2+. Some ions and natural organic materials, which commonly exist in natural water, were also tested to evaluate their potential impacts on the degradation of AO7. The degradation efficiency of AO7 was up to 95% under the optimized test conditions, where the ferrous/percarbonate/AO7 molar ratio was 15/10/1 in the 0.285 mmol/l AO7 aqueous solution. The presence of Cl−, SO42−, NO3−, Na+, and Mg2+ did not affect the removal of AO7. The addition of HCO3− significantly inhibited its removal, even when the concentration of HCO3− was low to 0.6 mmol/l. A slight inhibition effect was observed when the added concentration of humic acid ranged from 0.5 to 5 mg/l, whereas the residue of AO7 was significantly enhanced when the level of humic acid was continually increased from 50 to 100 mg/l. Hydroxyl radicals (•OH) were the main reactive intermediates controlling the oxidation of AO7 in the present Fe2+/SPC system. The produced intermediates through the degradation of AO7 were identified to include 2‐coumaranone, 2‐naphthol, phthalic acid, phthalimide, N‐methylnaphthylamine, and 2‐methylphenol. The proposed degradation pathways are consistent with the radical formation and the identified intermediates. Practitioner Points: The ferrous/percarbonate system can remove 95% of AO7 under the optimized conditions.AO7 removal was inhibited by adding HCO3− and humic acid, but not affected by Cl−, SO42−, NO3−, Na+, and Mg2+.Hydroxylation, ring opening, and mineralization driven by the generated hydroxyl radicals were derived as the major processes for degrading AO7. [ABSTRACT FROM AUTHOR]

With the booming development and application of ocean exploration and investigation, it has become more and more important to achieve underwater communications for the establishment of global networks. This paper deals with a Monte Carlo-based performance analysis on multi-mode continuous-variable quantum key distribution over underwater links, where Monte Carlo model can characterize the complex probability density of underwater components. Compared with previous studies carried out in single-mode setting, the multi-mode protocol admits higher secret key rate. Last but not least, using non-Gaussian operations, we further improve the performance of multi-mode protocol, since it increases and distills entanglement in Gaussian entangled states. [ABSTRACT FROM AUTHOR]

We propose a new scheme to strengthen the performance of the discrete-modulated continuous-variable measurement-device-independent quantum key distribution (DM-CV-MDI-QKD) protocol by introducing a quantum scissors (QS) operation to Bob's side. According to the equivalent one-way scheme of the protocol, we further investigate the success probability of the QS operation, and analyze the security of the DM-CV-MDI-QKD equipped with this operation in the asymptotic case. Simulation results show that the QS operation can indeed effectively improve the performance of the existing protocol, and compared with the scheme without QS operation, our proposed scheme has a higher secret key rate and a longer secure transmission distance. [ABSTRACT FROM AUTHOR]

Numerous continuous-variable quantum key distribution (CV-QKD) schemes are based on the Gaussian modulation, which is carried out in conjugate quadratures. In order to simplify the traditional protocols, as well as improving the security of the system, we propose the plug-and-play unidimensional CV-QKD protocol, which waives the necessity of propagating a local oscillator (LO) between legitimate users and generates a real local LO for quantum measurement. The new protocol utilizes only one phase modulator rather than two, which is different from the dual-phase-modulated coherent-states protocol that we proposed earlier. The prepare-and-measure and entanglement-based schemes are described. The security of the new protocol against collective attacks in a Gaussian channel is analyzed, and the security boundary is derived, which is achieved by establishing the relationship between the uncertain parameters of the unmodulated quadrature. The performance of it is analyzed in both asymptotic and finite-size cases. Such an efficient scheme not only provides a way of removing the security loopholes associated with the transmitting LO, but also eliminates the need for one of the phase modulators, and thus will facilitate commercialization of continuous-variable quantum key distribution. [ABSTRACT FROM AUTHOR]

Continuous variable quantum teleportation (CVQT) is one of the technologies currently explored to implement global quantum networks. Entanglement source is an indispensable resource to realize CVQT, and its distribution process has natural symmetry. Though there are many results for CVQT over optical fiber or atmospheric channel, little attention is paid to seawater channel. In this paper, a model based on seawater chlorophyll concentration is used to study the attenuation effect of seawater on light. In our scheme, a noiseless linear amplifier is utilized for enhancing the performance of CVQT under seawater channel. Simulation results show that the proposed scheme has an improvement in terms of fidelity and maximum transmission distance compared with the original scheme. [ABSTRACT FROM AUTHOR]

In satellite-to-submarine quantum communication, sea surface, which may cause refraction and propagation light deflection, is a non-negligible obstacle. These negative effects can result in severe performance decrease. In this paper, we carry out satellite-to-submarine quantum communication by taking advantage of the principle of measurement-device-independent continuous-variable quantum key distribution (MDI-CVQKD). In particular, by deploying the untrusted party Charlie on the sea surface, the satellite-to-submarine quantum channel can be divided into two parts, namely the atmospheric channel and the seawater channel. Quantum signals no longer need to pass through the sea surface, but can be directly measured at Charlie's station. In this way, negative effects caused by the sea surface can be tactfully eliminated. Security analysis shows that our proposed scheme is feasible, thereby providing a novel thought to implement satellite-to-submarine quantum communication. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics and mechanism of a simple system, Co2+–HCO3 −–H2O2 for degrading highly stable organic pollutants have been reported. Fast and versatile decolorization of organic dyes was observed in an aqueous solution containing 10mM NaHCO3, 10μM Co2+ ions and 10mM H2O2, while the degradation rate of p-nitrophenol and 2,4-dinitrophenol was very slow. From cyclic voltammetry and UV–vis spectra, it was found that different complexes between Co2+ ions and methylene blue (MB) were formed in HCO3 − solution, and being confirmed by photoluminescence probing and electron spin resonance spin-trapping technologies, the 1:1 complex [CoII(HCO3 −)(MB)]+ was more efficient in catalyzing decomposition of H2O2 into ls. The other tested pollutants also played an important role in the rate of ls production in the system. Based on the kinetic observations of MB decolorization, a possible mechanism was proposed. [Copyright &y& Elsevier]

Side-channel attack is a serious impairment for the key generation processing in the continuous-variable quantum digital signature protocol. Based on measurement-device-independent components, we present a continuous-variable quantum digital signature protocol, so that the topology removes the loopholes of the practical detectors and eliminates all side-channel attacks. Without loss of generality, we consider the protocol involving three participants, whom independently decides whether to send a quantum pulse or a local oscillator pulse to the intermediate station at any time window. What's more, we propose to employ phase-encoding and state-encoding strategies simultaneously that performing once key generation processing can obtain twin signatures. We hope the proposed protocol could further improve the performance of quantum digital signature. [ABSTRACT FROM AUTHOR]

Low valent manganese species and surface oxygen vacancies in OMS-2 play an important role in catalytic reactions, and it is highly desirable and challenging to develop a feasible strategy of increasing the Mn(II) and Mn(III) species concentration in the oxide. Herein, the OMS-2/g-C 3 N 4 hybrids (OMS-2/CN) were prepared by a facile refluxing approach. It was found that the MnO x precursor from the reaction of KMnO 4 and MnSO 4 was transformed into OMS-2 nanofibers with the formation of more Mn(II) and Mn(III) species in OMS-2 and the destruction and oxidation of g-C 3 N 4. The hybrids exhibited higher efficiency for pollutants degradation in the presence of PMS than the pure OMS-2 or g-C 3 N 4 . There was a linear correlation between the specific initial rate and the ratio of Mn(II + III)/Mn(IV). Mechanism investigation indicated that high active manganese species or caged radicals were produced through the oxidation of Mn(II) and Mn(III) by PMS and contributed to the degradation reaction. During five consecutive cycles, the catalyst exhibited good reusability and stability. Therefore, the OMS-2/CN hybrids are promising catalysts for wastewater treatment with PMS as the oxidant. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride materials (g-C 3 N 4 ) were prepared from melamine hydrochloride under different calcination temperatures, and were investigated as metal-free catalysts for Acid Orange 7 degradation in the presence of peroxymonosulfate (PMS) under visible light. It was found that with the increase of calcination temperature, the morphological features of g-C 3 N 4 change from a typical flat layer structure with numerous mesopores to a thinner platelet-like structure, accompanied by the increase of BET surface area. The increase of heating temperature can also enlarge the band gap of g-C 3 N 4 . But under a higher temperature of 600 °C, the band gap is significantly reduced, probably due to the decrease of the structure defects. The obtained samples can effectively activate PMS under visible light irradiation to generate reactive species such as sulfate radicals, superoxides and photogenerated hole for dye degradation. Compared with the samples obtained from melamine, the activity is much higher, attributed to the dramatic enhancement of BET surface area. The catalysts also present a long-term stability during multiple runs. The effect of several reaction parameters and the formation of intermediates were also discussed. This study can improve our understanding of PMS activation on g-C 3 N 4 catalysts under visible light for pollutants removal. [ABSTRACT FROM AUTHOR]

With the increasing use of biodiesel and its blends with petroleum fuel, the corresponding environmental issues also occur during its production, application and transportation. The photolysis behavior for biodiesel and the impacts of biodiesel on the photo-oxidation of petroleum hydrocarbons in simulated freshwater was studied by irradiated with ultra violet (UV) and simulated sunlight in the present study. The results indicated that the photolysis rates of fatty acid methyl esters (FAMEs) were mainly depended on their degree of saturation, slightly on water matrices and the initial concentration of biodiesel, regardless of biodiesel sources. Similar results were observed for total organic carbon (TOC) removal rates; however, TOC removal rates were slightly dependent on the initial concentration of biodiesel. The presence of humic acid and pyrogallic acid or lake water matrices slightly inhibited the removal rates of TOC. The photolysis rates of individual petroleum hydrocarbons with and without the presence of biodiesel followed similar rules. In brief, alkanes with light molecular weights were transformed faster than those with heavy molecules, the removal of polycyclic aromatic hydrocarbons (PAHs) were more significantly than alkanes, and the removal of alkylated PAHs (APAHs) increased concurrently with the alkylation level in each family. The presence of biodiesel only inhibited the photolysis of some heavy alkanes and PAHs, not for all other petroleum hydrocarbons. Biodiesel, as a surfactant-like material, could stabilize small oil droplets initially formed by agitation, therefore, these droplets experience longer lifetimes in the water phase before re-aggregating into larger globules and rising to the surface. The apparent solubility of petroleum hydrocarbons, especially for those with heavier molecular weights, has been enhanced in the presence of FAMEs. In this scenario, light needs to penetrate water phase to degrade these targets compared with diesel alone. The direct contacting opportunities between UV light and targets, and radicals produced to attack targets were reduced, which finally resulted in the inhibited photolysis rates of some heavy molecular weight hydrocarbons. [ABSTRACT FROM AUTHOR]

• MnHA hybrid was prepared by deposition of HA on OMS-2. • Synergistic activation of PMS by MnHA hybrid was observed. • Interaction between OMS-2 and HA was characterized and discussed. • Detailed mechanism of MnHA+PMS system was proposed. The development of environmental friendly and efficient catalysts in advanced oxidation processes to degrade organic pollutants is highly desired. The complex metal oxides usually exhibit superior performance due to the potential synergistic effects between different metal oxides. In this study, hydroxyapatite (HA) coupled with manganese oxide OMS-2 hybrid (MnHA) was prepared and investigated as a catalyst for synergistic activation of peroxymonosulfate (PMS). The degradation of Acid Orange 7 with the hybrid was 2.94 and 10.8 times higher than those with pure OMS-2 and HA respectively. More importantly, it was found that Ca was not only coordinated with P O/P O groups in HA but also with Mn O groups on the surface of OMS-2; and then electrons were suggested to be transferred from HA to OMS-2 to decrease the Mn O Mn bond energy, leading to easier oxidation of Mn species by PMS. HO, SO 4 − , O 2 − and 1O 2 were found to be involved as reactive species in MnHA+PMS system, but 1O 2 played a more important role. The performance of the system under different conditions such as solution pH and concentrations of catalyst, pollutant and PMS was also studied. This work is expected to be helpful to design new and highly active catalysts for PMS activation. [ABSTRACT FROM AUTHOR]

Structurally defected cryptomelane-type octahedral molecular sieve (SDOMS-2) was successfully prepared at room temperature for efficient activation of peroxymonosulfate (PMS). The catalyst was easily fabricated by redox reaction of acidic KMnO 4 and MnSO 4 with the presence of graphite at 25 °C for 96 h. XRD and N 2 adsorption-desorption measurements confirmed the OMS-2 crystal with a high surface area of 118 m2/g. Evidence by Raman, XPS, cyclic voltammogram (CV), SEM and TEM, the slow-growing SDOMS-2 nanorods exhibited more structural defects and lower valance of manganese than the conventional OMS-2 prepared by a refluxing method. The SDOMS-2 catalyst showed high activity and stability in terms of Acid Orange 7 (AO7) degradation in the presence of PMS, and the initial degradation rate was 4 times of the refluxed OMS-2. Synthesis conditions influenced the surface morphology and detective structure of OMS-2, and thus appeared to play critical roles in PMS activation. Based on the scavenger experiments, 1O 2 was identified as dominant oxygen species in the SDOMS-2 + PMS system for AO7 degradation. This study demonstrates a novel and simple technology for the preparation of SDOMS-2 for PMS activation. Unlabelled Image • Structural defective OMS-2 nanorods were successfully prepared at room temperature. • Activation of PMS using structurally defected OMS-2 showed a superior effect on degradation of AO7. • O 2 ●- and 1O 2 , rather than SO 4 -● and HO•, were the dominant species responsible for the degradation. [ABSTRACT FROM AUTHOR]