Search

Abstract Background Over the years, mesenchymal stromal (stem) cells (MSCs) have been pre-clinically applied in the treatment of variety kinds of diseases including asthma and chronic lung diseases. Aim of the current study was to systematically review and to conduct meta-analysis on the published studies of MSC treatment in asthma animal models. Methods Publications on the MSC and asthma treatment was thoroughly searched in the electronic databases. Statistical analysis was then performed using the Comprehensive Meta-Analysis software (Version 3). Effect of MSC therapy on asthma model was assessed by Hedges's g with 95% confidence intervals (95% CIs). Random effect model was used due to the heterogeneity between the studies. Results Meta-analysis of the 32 included studies showed that MSC transplantation was significantly in favor of attenuating lung injury and remodeling (Hedges's g = −9.104 ± 0.951 with 95% CI: −10.969 ∼ −7.240, P < 0.001) and airway inflammation (Hedges's g = −4.146 ± 0.688 with 95% CI: −5.495 ∼ −2.797, P < 0.001). The mechanism of MSC therapy in asthma seems to be regulating the balance of Th1 cytokine and Th2 cytokines (IFN- γ : Hedges's g = 4.779 ± 1.408 with 95% CI: 1.099–2.725, P < 0.001; IL-4: Hedges's g = −10.781 ± 1.062 with 95% CI: −12.863 ∼ −8.699, P < 0.001; IL-5: Hedges's g = −10.537 ± 1.269 with 95% CI: −13.025 ∼ −8.050, P < 0.001; IL-13: Hedges's g = −6.773 ± 0.788 with 95% CI: −8.318 ∼ −5.229, P < 0.001). Conclusion Findings of the current systemic review suggested a potential role for MSCs in asthma treatment although it is still challenging in clinical practice. The mechanisms of MSCs in pre-clinical asthma treatment may be associated with attenuating airway inflammation through regulating Th1 and Th2 cytokines. [ABSTRACT FROM AUTHOR]

In order to separate In(III) and Fe(III) from the sulfate leaching solution, solvent extraction with Di-2-ethylhexylphosphoric acid (D2EHPA) was investigated using a Impinging Stream–Rotating Packed Bed (IS–RPB) contactor in laboratory scale. The effects of operating parameters, such as feed solution pH, flow rate ratio, the high gravity factor, the concentration of D2EHPA, initial iron concentration, stripping solution concentration were examined. The experimental results showed that the IS–RPB was effective in the separation of In(III) and Fe(III)under favorable operating conditions. The extraction and stripping efficiency as high as 99% could be achieved, at a separation factor in excess of 3000. Compared with other mixing devices, IS–RPB contactor has better micromixing characteristics, which has a good application prospect. [ABSTRACT FROM AUTHOR]

The microwave irradiation is used to roast zinc slag oxidation dust in the presence of concentrated sulfuric acid with the aim of accelerating roasting process. The roasted material is leached with tap water for the recovery of zinc and indium. The influence of roasting temperature, particle size, and the ratio of acid to ZSOD mass on the rate of roasting reactions were investigated. The results show that the extraction rate of zinc and indium increases with increasing the roasting temperature and the ratio of acid to ZSOD mass, while decreases with increase in the particle size. The samples were characterized using XRD and SEM. Under the conditions employed in the present work a maximum recovery of 94% and 90% of zinc and indium could be achieved. Shrinking core model was used to describe the kinetic parameters and to identify the rate controlling step. Both zinc and indium extraction were controlled by the internal diffusion in the solid product layer, with the apparent activation energy of the roasting reaction were 15.94 kJ/mol and 12.68 kJ/mol respectively. The reaction order with respect to concentrated sulphuric acid was 1.75 and 1.59 for zinc and indium, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a solution to satisfy the increasing requirements for secure medical image transmission and storage over public networks. The proposed scheme can simultaneously encrypt and compress the medical image using compressive sensing (CS) and pixel swapping based permutation approach. In the CS phase, the plain image is compressed and encrypted by chaos-based Bernoulli measurement matrix, which is generated under the control of the introduced Chebyshev map. The quantized measurements are then encrypted by permutation-diffusion type chaotic cipher for the second level protection. Simulations and extensive security analyses have been performed. The results demonstrate that at a large scale of compression ratio the proposed cryptosystem can provide satisfactory security level and reconstruction quality. [ABSTRACT FROM AUTHOR]

Nowadays, the increasing demand for telemedicine services has raised interest in the real-time medical image protection literatures. In this paper, we evaluate the security of an efficient and secure medical image protection scheme recently proposed (Fu et al., 2013). It is found that this scheme can be successfully broken by launching chosen-plaintext attacks. Improvement is subsequently developed for promoting the security and efficiency performance. Extensive security analyses and experimental results both indicate that the improved scheme can well address the security flaws and advance the speed performance of the original one. [ABSTRACT FROM AUTHOR]

The dielectric properties of petroleum coke at five temperatures between 20 to100∘C, covering different moisture content levels at 2.45 GHz, were measured using an open-ended coaxial probe dielectric measurement system. The effects of drying temperature, duration of drying, and sample mass on the moisture content and dehydration rate of petroleum coke was assessed utilizing the response surface methodology. The dielectric constant, loss factor, and loss tangent were all found to increase nearly linearly with increase in moisture content. Three predictive empirical models were developed to relate the dielectric constant, loss factor, and loss tangent of petroleum coke as a linear function of moisture content from 3–10%. An increase in temperature between 20 to100∘Cwas found to increase the dielectric properties. The penetration depth was observed to increase linearly with decrease in moisture content in the range of 3 to 10%. A predictive empirical model was developed to calculate penetration depth for petroleum coke. Two mathematical models were established and analyzed using RSM to describe the relationship between the microwave drying conditions and the responses, moisture content, and dehydration rate. Statistical analysis with response surface regression showed that microwave drying temperature, duration of drying, and sample mass were significantly related to moisture content and dehydration rate. Based on the RSM analysis, the optimum process conditions were estimated to be a microwave drying temperature of75∘C, drying duration of 10 sec, and sample mass of 60 g, with the resultant moisture content being 0.34 at a dehydration rate of 2.94 g/min. [ABSTRACT FROM PUBLISHER]

Finding promising materials that show large thermoelectricity at low temperatures is crucial for low-temperature refrigeration applications. Here, we report a significantly large thermoelectric power factor (PF) up to 50 μW cm−1 K−2 at an extremely low temperature of ∼8 K in a quasi-one-dimensional (Q1D) antiferromagnet KMn6Bi5, in which highly electrical conductivity and dramatic enhancement of Seebeck coefficient may favor its occurrence. In addition, a giant Nernst signal has also been detected with a maximum value of 24 μV K−1 T−1 at ∼5 K. All these intriguing characteristics observed in KMn6Bi5 can be attributed to the manifestation of the unusually strong coupling among spin, charge, lattice, and one dimensionality in KMn6Bi5. Our findings provide fundamental insight into the thermal transport in Q1D antiferromagnets and should stimulate further experimental exploration of thermal transport in such Q1D family for possible thermoelectric applications at extremely low temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Woodceramics samples derived from carbonized tobacco stems and different contents of phenolic resin, using different carbonization temperatures have been investigated by Raman spectroscopy. It was found that the full width at half maximum (FWHM) and the R-value decreased with an increase of the carbonization temperature and the content of phenolic resin. And the crystallite size L a of these samples show low microcrystalline size, i.e. L a varying between 1.85 and 5.40nm. The results obtained indicate that 973K is the turning point temperature for the preparation of woodceramics. The results of Raman spectra were confirmed by SEM results of the woodceramics. [Copyright &y& Elsevier]

Abstract: In this paper, activated carbons with high surface area from carbonized tobacco stems with K2CO3 activation by microwave radiation were investigated. Effects of microwave radiation time and K2CO3/C ratio on the yield and adsorption capacities of activated carbons were evaluated. Experimental results indicated that the optimum conditions were as follow: microwave power 700W; microwave radiation time 30min; K2CO3/C ratio 1.5:1. Iodine number, amount of methylene blue adsorption and the yield of activated carbon prepared under optimum conditions were 1834mg/g, 517.5mg/g and 16.65%, respectively. Surface area, micropore volume and pore size distribution (PSD) of the carbons were determined by the BET, H-K and DFT methods. Results showed that activated carbons had a micropore content about 59.98% and a small number of mesopores and macropores; BET specific surface area and total pore volume were 2557m2/g and 1.647cm3/g, respectively. [Copyright &y& Elsevier]

Background: Early prediction of delayed cerebral ischemia (DCI) is critical to improving the prognosis of aneurysmal subarachnoid hemorrhage (aSAH). Machine learning (ML) algorithms can learn from intricate information unbiasedly and facilitate the early identification of clinical outcomes. This study aimed to construct and compare the ability of different ML models to predict DCI after aSAH. Then, we identified and analyzed the essential risk of DCI occurrence by preoperative clinical scores and postoperative laboratory test results. Methods: This was a multicenter, retrospective cohort study. A total of 1039 post-operation patients with aSAH were finally included from three hospitals in China. The training group contained 919 patients, and the test group comprised 120 patients. We used five popular machine-learning algorithms to construct the models. The area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, specificity, precision, and f1 score were used to evaluate and compare the five models. Finally, we performed a Shapley Additive exPlanations analysis for the model with the best performance and significance analysis for each feature. Results: A total of 239 patients with aSAH (23.003%) developed DCI after the operation. Our results showed that in the test cohort, Random Forest (RF) had an AUC of 0.79, which was better than other models. The five most important features for predicting DCI in the RF model were the admitted modified Rankin Scale, D-Dimer, intracranial parenchymal hematoma, neutrophil/lymphocyte ratio, and Fisher score. Interestingly, clamping or embolization for the aneurysm treatment was the fourth button-down risk factor in the ML model. Conclusions: In this multicenter study, we compared five ML methods, among which RF performed the best in DCI prediction. In addition, the essential risks were identified to help clinicians monitor the patients at high risk for DCI more precisely and facilitate timely intervention. [ABSTRACT FROM AUTHOR]

This paper presents a solution for secure and efficient image encryption with the help of self-adaptive permutation–diffusion and DNA random encoding. The plain image is firstly converted to DNA sequence using random encoding rules, so as to disarrange the bit distribution of the plaintext. A self-adaptive permutation–diffusion procedure is subsequently introduced for further encryption. The quantization processes of the permutation and diffusion procedures are disturbed by the intrinsic features of the plaintext, with the introduced disturbances can be automatically retrieved in the decryption end. The security of the system originates from the plaintext-related quantization of the encryption process which makes the cryptosystem secure against plaintext attack. Besides, the reusability of the random variables can dramatically promote the efficiency of the cryptosystem, which renders great potential for real-time secure image applications. [ABSTRACT FROM AUTHOR]

Background Nicotine craving and relapse often occurs after reactivation of nicotine reward memories. We recently developed a memory retrieval–reconsolidation interference procedure in which reactivating nicotine reward memories by acute exposure to nicotine (the unconditioned stimulus [UCS]) and then pharmacologically interfering with memory reconsolidation decreased relapse to nicotine seeking in rats and nicotine craving in smokers. Here, we investigated underlying mechanisms. Methods In the first series of experiments, we trained rats for nicotine-induced conditioned place preference (CPP) or nicotine self-administration and ventricularly microinjected them with the protein synthesis inhibitor anisomycin immediately after UCS-induced memory retrieval. In the second series of experiments, we used tyramide-amplified immunohistochemistry–fluorescence in situ hybridization to examine neural ensembles in the basolateral amygdala (BLA) reactivated by nicotine conditioned stimulus– or UCS-induced memory retrieval. We then used the Daun02 chemogenetic inactivation procedure to selectively inhibit the nicotine UCS-reactivated BLA neuronal ensembles. Results Ventricular injections of the anisomycin immediately after nicotine UCS memory retrieval inhibited subsequent nicotine CPP and relapse to operant nicotine seeking after short or prolonged abstinence. More important, within BLA, distinct neuronal ensembles encoded pavlovian CPP and operant self-administration reward memories and nicotine (the UCS) injections in the home cage reactivated both neuronal ensembles. Daun02 chemogenetic inactivation of the nicotine-reactivated ensembles inhibited both nicotine CPP and relapse to nicotine seeking. Conclusions Results demonstrate that the nicotine UCS-induced memory retrieval manipulation reactivates multiple nicotine reward memories that are encoded by distinct BLA neuronal ensembles that play a role in nicotine preference and relapse. [ABSTRACT FROM AUTHOR]

In the process of steel manufacture, up to ten millions of tons of sintering dust (SD) are produced annually in China, which contain noble metals such as Ag. Therefore, recovery of silver (Ag) from SD could be a potential economic and environmental activity. The purpose of this article is to generate information about reaction kinetics of silver leaching with thiourea from SD, comparing the conventional and ultrasonic-augment leaching. The effects of various control parameters such as the ultrasound power, particle size, leaching temperature and thiourea concentration on leaching rate of silver were studied. The results showed 89% silver recovery for conventional process against 95% for ultrasound assisted leaching. The ultrasonic wave increased the leaching rate and shorten the reaction time. The rate controlling step was analyzed using shrinking core model and the rate controlling step is identified to be the diffusion through the product layer in both conventional and ultrasonic-augment leaching processes. The activation energies were estimated to be 28.01 kJ/mol and 18.19 kJ/mol, and the reaction order were 0.89 and 0.71, respectively. [ABSTRACT FROM AUTHOR]

DISCUSSION Effectiveness of PAs with different baselines Our results suggested that 170 of the 338 PAs (50.30%) had significant positive effects, including 150 PAs with low HPI baselines, 12 PAs with medium HPI baselines, and 8 PAs with high HPI baselines (Figure 2b). Our previous studies also showed that unlike PAs with high HPI or medium HPI baselines, PAs with low HPI baselines are more likely to have effective management if they have good patrol and surveillance, which helps control illegal threats in PAs (Wang et al., 2021). Compared with PAs with low HPI and medium HPI baselines, the area of forests in PAs with high HPI baselines of built-up area was relatively higher (Appendix S2). From 2010 to 2020, the rate of forest area decrease was the fastest for PAs with high HPI baselines, followed by PAs with medium HPI baselines and PAs with low HPI baselines (Figure 4a). [Extracted from the article]

We report the transport properties of a topological insulator candidate, LiMgBi. The electric resistivity of the title compound exhibits a metal-to-semiconductor-like transition at around 160 K and tends to saturation below 50 K. At low temperatures, the magnetoresistance is up to ∼260 % at 9 T and a clear weak antilocalization effect is observed in the low magnetic-field region. The Hall measurement reveals that LiMgBi is a multiband system, where hole-type carriers (n h ∼ 1018 cmâˆ'3) play a major role in the transport process. Remarkably, LiMgBi possess a large Seebeck coefficient ∼440 ÎĽV/K) and a moderate thermal conductivity at room temperature, which indicate that LiMgBi is a promising candidate in thermoelectric applications. [ABSTRACT FROM AUTHOR]

Superconducting circuit quantum electrodynamics (QED) architecture composed of superconducting qubit and resonator is a powerful platform for exploring quantum physics and quantum information processing. By employing techniques developed for superconducting quantum computing, we experimentally investigate phase-sensitive Landau–Zener–Stückelberg (LZS) interference phenomena in a circuit QED. Our experiments cover an extensive range of LZS transition parameters and demonstrate the LZS induced Rabi-like oscillation as well as phase-dependent steady-state population. [ABSTRACT FROM AUTHOR]

Copper and cobalt usually coexist in the leachate of waste lithium ion batteries, sea nodules and other copper ore or by-product. Conventional methods for the separation of copper and cobalt hardly avoid some defects, such as longer extraction time, co-extraction and too many stages. In this paper, a microfluidic extraction procedure for simultaneously separating copper (Cu2+) and cobalt (Co2+) ions in a microchannel was investigated. In addition, some key operation parameters, such as initial pH, volume flow rate and extractant concentration, were optimized by a method of response surface methodology (RSM). The result showed that under the optimized operation parameters of initial pH of 2.5, volume flow rate of 0.035mLmin-1 and extractant concentration of 17.36%, the extraction rate of copper could be as high as 96.73%, with a low cobalt extraction rate, which was only 2.41%. [ABSTRACT FROM AUTHOR]

In this paper, a security enhancement for double random phase encoding (DRPE) by introducing a rear-mounted phase masking procedure is presented. Based on exhaustively studying the cryptanalysis achievements of DRPE and its variants, invalidation of the second lens, which plays a critical role in cryptanalyzing processes, is concluded. The improved system can exploit the security potential of the second lens and consequently strengthen the security of DRPE. Experimental results and security analyses are presented in detail to demonstrate the security potential of the proposed cryptosystem. [ABSTRACT FROM AUTHOR]

The simulation of bubbling fluidized beds (BFB) residence time distribution (RTD) based on the structure-based drag model are conducted for the single and binary gas-solid phases systems, a comparison of computed results with experimental data proves that our model is applicable to both systems with better accuracy. The revised drag coefficient ( H d ) increases with decreasing the gas velocity or increasing the particle diameter. The increase of the feed rate could improve the solids flow pattern to be close to the plug flow, while increasing gas velocity or bed height would lead to a wider RTD. The particles in the binary mixture are in more diffusion-oriented movement so as to have less MRT (mean residence time) than that of the single system. The coarse particles with longer MRT are simulated to accumulate into the bed bottom with a slower vertical velocity. [ABSTRACT FROM AUTHOR]

This paper presents an information authentication scheme using sparse representation of double random phase encoding in fractional Fourier transform domain. Different from traditional cryptographic applications, only sparse version of the ciphertext is available at the receiver end. The decrypted image is unrecognizable and of no meaningful information of the plaintext, which can enhance the resistance against various attacks. The decrypted image can be authenticated using nonlinear optical correlation approach. Numerical simulations have been carried out, and the results prove the effectiveness and noise resistance of the proposed scheme. [ABSTRACT FROM AUTHOR]

Aiming to comprehensively improve the safety of energetic materials by minimizing their sensitivity to external stimuli such as impact, friction, static electricity and heat, a bionic functional layer strategy is developed to construct energetic composites with core-shell-shell structure. The morphology and structure of the samples were characterized in depth by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectra (XPS). The results show that the bionic functional layer forms a dense and complete shell layer on the surface of energetic material, the two-dimensional (2D) material is uniformly and tightly coated on the surface of energetic material based on the super adhesion of the functional interface layer, and the core-shell-shell structure CL-20@Polydopamine@Graphene Oxide (CL-20@PDA@GO) is successfully prepared. The preparation process does not cause the crystalline transformation of energetic material. In addition, the impact sensitivity, friction sensitivity, electrostatic accumulation characteristics and thermal properties of the samples were also evaluated. The results indicate that the bionic functional layer and 2D material can synergistically reduce the sensitivity of energetic material to external stimuli based on their intrinsically superior properties. Therefore, synergistic effect of bionic functional layer strategy in this work has the potential to be extended for multiple properties regulation of energetic materials. • Bionic functional layer-based strategy for constructing core-shell-shell structural composites. • A dense and complete PDA shell layer is uniformly encapsulated on the CL-20 surface. • The bionic functional layer enhances the interfacial interaction between the 2D materials and the energetic materials. • The synergistic effect of functional interface layers and 2D materials reduces the sensitivity of energetic materials. [ABSTRACT FROM AUTHOR]

The effects of process conditions on preparation of U 3 O 8 by calcination from ammonium uranyl carbonate in microwave fields were assessed and optimized for maximizing the total uranium as well as calcination temperature, adopting as Central Composite Design (CCD) methodology. The process variables assessed were calcination temperature, calcination duration and mass of sample. A quadratic model relating the process variables and the total amount of uranium and U 3 O 8 was proposed eliminating the insignificant parameters. The optimal calcination conditions were estimated to be a calcination temperature of 942.75 K, calcination duration of 8.78 min, with the corresponding total uranium and U 3 O 8 to be 82.07% and 31.33%, respectively. [ABSTRACT FROM AUTHOR]

Optical information security systems have drawn long-term concerns. In this paper, an optical information authentication approach using gyrator transform based double random phase encoding with sparse representation is proposed. Different from traditional optical encryption schemes, only sparse version of the ciphertext is preserved, and hence the decrypted result is completely unrecognizable and shows no similarity to the plaintext. However, we demonstrate that the noise-like decipher result can be effectively authenticated by means of optical correlation approach. Simulations prove that the proposed method is feasible and effective, and can provide additional protection for optical security systems. [ABSTRACT FROM AUTHOR]

The clean utilization of the CuCl residue containing chloride produced from zinc hydrometallurgy residue is very important for the recycling of valuable metals. In order to strengthen the process of dechlorination, a new method of microwave roasting under the atmosphere of steam and oxygen was put forward. It was demonstrated that the dechlorination rate of CuCl residue by microwave roasting was higher than that of conventional roasting by tubular resistance furnace under the same conditions (temperature, holding time and atmosphere). After roasting at a temperature of 450 °C for 80 min under a gas flow rate of 150 mL/min in microwave filed, the dechlorination rate of CuCl residue was as high as 97%, increasing 18% compared to that of conventional roasting using tubular resistance furnace. The chatacterization of phases variation of CuCl residue in microwave field by means of XRD, SEM-EDS and Raman spectroscopy indicated that the process of dechlorination by microwave roasting under the atmosphere of steam and oxygen was much more efficient than conventional roasting. [ABSTRACT FROM AUTHOR]

Crofton weed was converted into a high-quality activated carbon (CWAC) via microwave-induced CO2 physical activation. The operational variables including activation temperature, activation duration and CO2 flow rate on the adsorption capability and activated carbon yield were identified. Additionally the surface characteristics of CWAC were characterized by nitrogen adsorption isotherms, FTIR and SEM. The operating variables were optimized utilizing the response surface methodology and were identified to be an activation temperature of 980 °C, an activation duration of 90 min and a CO2 flow rate of 300 ml/min with a iodine adsorption capacity of 972 mg/g and yield of 18.03%. The key parameters that characterize quality of the porous carbon such as the BET surface area, total pore volume and average pore diameter were estimated to be 1036m²/g, 0.71 ml/g and 2.75 nm, respectively. The findings strongly support the feasibility of microwave heating for preparation of high surface area porous carbon from Crofton weed via CO2 activation. [ABSTRACT FROM AUTHOR]

Abstract: This preliminary study examined the role of microwave radiation on precipitation and aging of iron oxyhydroxides at 60°C. It was observed that due to rapid heating under microwave, transformation of two line ferrihydrite to α-Fe2O3 takes place within 4–10h. This is in contrast to the usual aging temperature of >100°C adopted in most conventional studies, and several days of aging. Besides rapid transformation, microwave helps forming nanoparticles, with crystallite size of ~60nm as determined from X-ray diffractograms, and <100nm particles as observed under TEM. Rapid transformation also promotes formation of α-Fe2O3 without the formation of intermediate γ-Fe2O3. This study brought out the advantages of low temperature microwave assisted precipitation/aging as a low energy process to transform iron oxyhydroxides, with likely applications in slurry rheology, synthesis of nanoparticles, and adsorption. [Copyright &y& Elsevier]

Abstract: The temperature rising characteristics of ammonium diurante, triuranium octaoxide (U3O8), and their mixture were investigated under microwave irradiation, aiming at exploring newly theoretical foundation for advanced metallurgical methods. The temperature rising curves showed that ammonium diurante had weak capability to absorb microwave energy, while triuranium octaoxide had the very strong absorption capability. The temperature of mixture containing 20% of U3O8 could rise from room temperature to 1171K within 280s. The ability to absorb microwave energy for the mixture with different ratios increased with the increase in the amount of U3O8. These are in good agreement with the results of Maxwell-Garnett effective medium theory. It is feasible to calcine ammonium diurante by adding of small amounts of U3O8 in microwave fields. [ABSTRACT FROM AUTHOR]

• A novel microwave-assisted method for preparing (NH 4) 6 Mo 7 O 24 ∙4H 2 O is proposed. • Microwave roasting is more effective and green compared to conventional roasting. • The leaching process of ammonium molybdate is optimized. • The purity of (NH 4) 6 Mo 7 O 24 ∙4H 2 O prepared by microwave roasting is higher. A novel and efficient microwave oxidation roasting method for preparing ammonium molybdate from molybdenum concentrate has been proposed and compared with the conventional roasting. TG-DTG, XRD, SEM-EDS, EDX and FTIR methods were used for characterization and analysis of oxidation roasting of ammonium molybdate. Based on the results of thermodynamic and dielectric properties of molybdenum concentrate, the effects of roasting temperature, roasting time, material mass and microwave power density on the oxidation degree of molybdenum concentrate were investigated. The influence of leaching agent, the concentrations of nitric acid and ammonia water on the leaching of ammonium molybdate was investigated. Under the same roasting conditions, the degree of oxidation of molybdenum concentrate by microwave roasting was higher than that of conventional roasting. Microwave roasting reduce the heating time of 30 min to reaction temperature and save 2.0 kW/h power in each roasting experiment. The optimal roasting and leaching conditions are as follows: roasting temperature of 600°C, roasting time of 2 h, power density of 100 W/g, nitric acid concentration of 0.80 mol/L, ammonia concentration of 25%. The purity and crystallinity of (NH 4) 6 Mo 7 O 24 ∙4H 2 O prepared by microwave roasting molybdenum concentrate are higher and better stability. [Display omitted] [ABSTRACT FROM AUTHOR]