Search

Esophageal squamous cell carcinoma (ESCC) is a major histological subtype of esophageal cancer with a poor prognosis. Although several serum metabolomic investigations have been reported, ESCC tumor-associated metabolic alterations and predictive biomarkers in sera have not been defined. Here, we enrolled 34 treatment-naive patients with ESCC and collected their pre- and post-esophagectomy sera together with the sera from 34 healthy volunteers for a metabolomic survey. Our comprehensive analysis identified ESCC tumor-associated metabolic alterations as represented by a panel of 12 serum metabolites. Notably, postoperative abrosia and parenteral nutrition substantially perturbed the serum metabolome. Furthermore, we performed an examination using sera from carcinogen-induced mice at the dysplasia and ESCC stages and identified three ESCC tumor-associated metabolites conserved between mice and humans. Notably, among these metabolites, the level of pipecolic acid was observed to be progressively increasing in mouse sera from dysplasia to cancerization, and it could be used to accurately discriminate between mice at the dysplasia stage and healthy control mice. Furthermore, this metabolite is essential for ESCC cells to restrain oxidative stress-induced DNA damage and cell proliferation arrest. Together, this study revealed a panel of 12 ESCC tumor-associated serum metabolites with potential for monitoring therapeutic efficacy and disease relapse, presented evidence for refining parenteral nutrition composition, and highlighted serum pipecolic acid as an attractive biomarker for predicting ESCC tumorigenesis.

Silicon (Si) is an ideal anode material for lithium ion batteries (LIBs) because of its high gravimetric capacity (3579 mAh g−1). However, Si anode undergoes sharp volume expansion during the charge/discharge process and then easily fragments to forfeit electronic contact, thereby forming dead Si, especially for micron-sized Si particles. We prepared a free-standing Si-based film anode, in which the micron Si particles are embedded by a coupled network of carbon nanotubes and the micro-nano structure is anchored by a carbon nanocoating layer. The networks can catch the nanominiaturized Si particles and provide continuous electrical contact during long cycling, thereby reviving the fragmented Si and maintaining lithium storage properties. This Si anode exhibits an ultra-high specific capacity of 3385.2 mAh g−1. The excellent cycling performance of 2345.3 mAh g−1 remained after 100 cycles at a current density of 0.3 A g−1. The pouch LIB based on the Si anode showed outstanding rate capacity and flexibility. This strategy is expected to solve the volume expansion and promote the application of the micron Si-based materials.

Metabolic reprogramming is a core hallmark of cancer and is key for tumorigenesis and tumor progression. Investigation of metabolic perturbation by anti-cancer compounds would allow a thorough understanding of the underlying mechanisms of these agents and identification of new anti-cancer targets. Here, we demonstrated that the administration of oleanolic acid (OA) rapidly altered cancer metabolism, particularly suppressing the purine salvage pathway (PSP). PSP restoration significantly opposed OA-induced DNA replication and cell proliferation arrest, underscoring the importance of this pathway for the anti-cancer activity of OA. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and 5′-nucleotidase (5′-NT), two metabolic enzymes essential for PSP activity, were promptly degraded by OA via the lysosome pathway. Mechanistically, OA selectively targeted superoxide dismutase 1 (SOD1) and yielded reactive oxygen species (ROS) to activate the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin complex 1 (mTORC1)/macroautophagy pathway, thus eliciting lysosomal degradation of HGPRT and 5′-NT. Furthermore, we found that the PSP was overactivated in human lung and breast cancers, with a negative correlation with patient survival. The results of this study elucidated a new anti-cancer mechanism of OA by restraining the PSP via the SOD1/ROS/AMPK/mTORC1/macroautophagy/lysosomal pathway. We also identified the PSP as a new target for cancer treatment and highlighted OA as a potential therapeutic agent for cancers with high PSP activity., Graphical abstract, Mechanistic study of natural compounds with anti-cancer activity would identify new targets for cancer treatment. Here we found that the purine salvage pathway (PSP) was a crucial target of oleanolic acid (OA) for cancer therapy. Moreover, OA suppressed PSP of cancer cells via activating the SOD1/ROS/AMPK/mTORC1/macroautophagy/lysosomal pathway.

Surrogate-assisted evolutionary algorithms have gained increasingly attention due to the promising search capabilities for solving computationally expensive optimization problems. However, when dealing with high-dimensional expensive optimization problems, the effectiveness of surrogate-assisted algorithms deteriorates drastically. In this paper, a novel and efficient hierarchical surrogate-assisted differential evolution (EHSDE) algorithm is proposed towards high-dimensional expensive optimization problems. To balance the exploration and exploitation during the optimization process, EHSDE utilizes a hierarchical framework. In the first phase, the best and the most uncertain offspring are identified respectively. The best offspring is prescreened by a global surrogate model which is built by using a radial basis function network with all the sample points, while the most uncertain offspring is built by the Euclidean distance between offspring and existing sample points. Subsequently, two local surrogate models, which are built by using the most promising sample points and the sample points surrounding the current best solution respectively, are utilized to accelerate the convergence speed. Moreover, experimental studies are conducted on the benchmark functions from 20D to 100D and on an oil reservoir production optimization problem. The results show that the proposed method is effective and efficient for most benchmark functions and for the production optimization problem compared with other state-of-the-art algorithms.

Sericin, produced in the middle silk gland (MSG) of silkworms, is a group of glue proteins that coat and cement silk fibers. Several genes are known to encode sericin, but their spatiotemporal regulation has yet to be fully elucidated. Here, we report in detail the expression profiles of the promoters of two major sericin-coding genes, Sericin 1 (Ser1)and Sericin 3 (Ser3), by analyzing Gal4/UAS transgenic silkworms. We found that UAS-linked EGFP fluorescence in transgenic silkworms driven by Ser1-Gal4was detected in only the R3, R4 and R5 regions of MSG starting inday-3 fifth-instar larvae and was continuously expressed until silk gland degradation. In transgenic silkworms driven by Ser3-Gal4, EGFP fluorescence was detected at a low level in the R2 region of MSG since the last day of fifth-instar larvae, and the expression increased during the wandering stages and was continuously detected until silk gland degradation. The molecular detection of EGFP expression in each of the Gal4/UAS transgenic silkworms was consistent with fluorescence observations. These findings reveal clear differences in the regulatory characteristics of the promoters of Ser1and Ser3 and provide new insights into the regulatory mechanism of the expression of sericin-coding genes.

The accumulation of α-syn which induce endoplasmic reticulum stress (ERS) and mediate various signaling pathways involved in DA neuronal degeneration, and the apoptosis of dopamine (DA) neurons are pathological markers of Parkinson’s disease (PD). High-temperature requirement protein A2 (HtrA2) is synthesized in the endoplasmic reticulum, and the expression level of HtrA2 can be upregulated by drugs or by unfolded proteins. Ucf-101 is a specific inhibitor of HtrA2, and studies have shown that Ucf-101 reduced apoptosis in PC12 cells. Our study showed that PC12 cells treated with 60 μM 6-OHDA for 24 h had significantly decreased cell viability compared to that of controls. A low concentration (2.5 μM) of Ucf-101 decreased the apoptosis rate of the PD cell model, but a high concentration (≥10 μM) increased the apoptosis rate, compared to that of controls. 6-OHDA upregulated the expression of HtrA2, α-syn, CHOP, Grp78 and active caspase-3 and reduced the levels of TH and XIAP. Ucf-101 reduced the level of ERS and apoptosis both in vivo and in vitro. The ratio of p-GSK3β (Tyr216 to Ser9) increased in PD rats. However, Ucf-101 down-regulated the activation of GSK3β and activated the Wnt/β-catenin pathway that was caused by 6-OHDA. Ucf-101 activated the Wnt/β-catenin pathway and significantly attenuated 6-OHDA-induced neurotoxicity, which was related to the inhibition of ERS and the reduction of the apoptosis rate of PC12 cells and DA neurons in the midbrain of PD rats. Ucf-101 has certain neuroprotective effects.

Hydrogel as a local drug depot can increase drug concentration at the tumor site. However, conventional drug-loaded hydrogel is typically formed by direct dissolution of drug molecules inside the hydrogel, which usually suffers from limited drug retention and poor tumor penetration. In this study, a nanocomposite hydrogel consisting of oxaliplatin (OXA)-conjugated G5 polyamidoamine (G5-OXA) and oxidized dextran (Dex-CHO) is constructed to improve local drug delivery. The OXA-containing nanocomposite hydrogel (denoted as PDO gel) is injectable and could maintain in vivo up to more than three weeks, which increases drug retention in tumor tissues. More interestingly, G5-OXA released from the PDO gel show potent tumor penetration mainly through an active transcytosis process. In vivo antitumor studies in an orthotopic 4T1 tumor model show that PDO gel significantly inhibits primary tumor growth as well as the metastasis. In addition, the PDO gel can also activate the immunosuppressive tumor microenvironment through immunogenic cell death effect, and further improves therapeutic efficacy with the combination of PD-1 antibody. These results demonstrate that the nanocomposite hydrogel can simultaneously enhance the retention and penetration of chemotherapeutic drugs via the combination of both advantages of hydrogel and nanoparticles, which provides new insights for the design of local drug delivery systems. STATEMENT OF SIGNIFICANCE: Hydrogel represents an important class of local drug delivery depot. However, conventional drug-loaded hydrogel is usually achieved by direct dissolution of small drug molecules inside the hydrogel, which typically suffers from limited drug retention and poor tumor penetration. Herein, we developed a nanocomposite hydrogel, which could gradually degrade and release drug-conjugated small nanoparticles (∼ 6 nm) for improved tumor penetration through the combination of an active transcytosis process and a passive diffusion process. This nanocomposite hydrogel system improved tumor penetration and retention of drug in primary tumors as well as the drug deposition in lymph nodes, which significantly suppressed tumor growth and metastasis.

Sinkianlignans A - D (1-4), four new sesquilignans with an unusual architectures was characterized with a rarely α-γ', β-γ', and γ-γ' linkage pattern, and sinkianlignans E - F (5 and 6), two lignans, were isolated from the Ferula sinkiangensis. Hypothetic biosynthetic pathway of compound 3 contain a newly formed six-membered C-ring by Diels-Alder cycloaddition. The structures of isolates were established by spectroscopic techniques and computational methods. Biological evaluation of all the isolated compounds revealed that compounds 2a and 2b could inhibit IL-6 and TNF-α production in lipopolysaccharide (LPS) induced RAW264.7 cells in a dose-dependent manner.

A mathematical model is presented for obtaining aero-optical wavefront of a light beam passing through the forced supersonic mixing layer for adaptive-optic (AO) correction, which is built based on the fact that the vortices in the forced flowfield and the associated aero-optical wavefront are regular and moreover they are predictable due to the usage of periodic flow control technique. An AO correction system is designed utilizing the model and tested numerically for various moments within a control period. The simulation results indicate that the AO correction system has a good capability of perfecting wavefront of the exit light beam again and thus its far field light intensity is improved greatly. For the aero-optical wavefront caused by the forced supersonic mixing layer, it can be approximately got using the built model, so the optical instrument used for wavefront detection, such as the wavefront sensor, is no longer needed in the proposed AO correction system. In the end, the practicality of experimental implementation of the designed AO correction system is briefly discussed.

Hydraulic fracturing is the pivotal technology of tight unconventional reservoir, and accurate monitoring of fracture morphology is related to fracturing effect evaluation, well productivity prediction and the follow-up measures. Compared with traditional methods, electromagnetic monitoring can obtain the Effective Propped Volume (EPV) that actually reflects the productivity, solve the abuse such as low fracture identification accuracy, limited by the specific time. This paper introduces an physical and numerical model that uses electromagnetic characteristics to accurately monitor the parameters of the fracture. A triaxial transmitting - triaxial receiving instrument which is approximate to the construction site is set up, the relationship of electromagnetic monitoring signals and the fracture parameters is obtained. By placing the transmission source plane perpendicular to an appropriate coordinate axis in a three-dimensional rectangular coordinate system the length and height of the fracture could be monitored by the signal of the long receiver while the transmitting source surface being perpendicular to the Z-axis. The azimuth could be inverted according to the magnitude of the signal peak when the transmitting source surface is perpendicular to the X-axis. The sign of azimuth could be determined by setting a M-axis (the Z axis rotates counterclockwise 45 degrees in the XZ plane).

The cavity configurations produced by discontinuities at thermal protection system coated at surface of reentry space vehicles can lead to separation, attachment, and even transition of gas flows around the vehicle's surface, which can bring serious aerodynamic heating during the space vehicles reentering the Earth's atmosphere. In this paper, the continuum, slip, and transition flow regimes are chosen to represent reentry atmosphere environment and then a numerical investigation of hypersonic gas flows over a family of cavities is performed by using the direct simulation Monte Carlo method to reveal flow structures in the cavity flowfield under different length-to-depth ratios and freestream incoming Mach numbers. In particular, when the freestream varies from the continuum to the transition flow regimes, the minimal length-to-depth ratios required for cavity flow becoming the closed type are 8, 6, and 5, respectively. The effect of the freestream incoming Mach number on the cavity flow characteristics is getting weaker when the freestream varies from the continuum to the transition flow regime. The two significant findings are that the cavity flow characteristics under hypersonic conditions are primarily determined by cavity geometry rather than freestream incoming Mach number and secondly, effect of the freestream incoming Mach number on cavity flow type is very slight if the freestream is in the transition flow regime.

Breast cancer is one of the most common malignancies and the leading cause of women's death, most of breast cancers are estrogen receptor-positive (ER+) breast cancer which can develop into advanced stage from early stage with treatment resistance. The purpose of this study was to investigate anti-ER+ breast cancer effects of 1,2,3,4,6-penta-O-galloyl-β- d -glucose (PGG) and its possible mechanisms. Cell viability was analyzed by MTT assay. The cell cycle distribution and apoptosis were detected by Flow cytometry. The expressions of cell proliferation- and apoptosis-related proteins were determined by western blot and immunofluorescence staining. The results showed PGG induced cytotoxicity and decreased viability of ER+ breast cancer T-47D and BT-474 cells. Flow cytometry analysis revealed that cell cycle was blocked in S phase at lower dose (25 μM PGG), and G1 phase at higher dose (50 or 75 μM PGG). One of the underlying mechanisms of the anti-cancer effect exerted by PGG was owed to inhibition of the expression of HURP, an up-regulated protein in human hepatocellular carcinoma which is closely related to tumor proliferation, invasion and metastasis. PGG affected cell cycle- or apoptosis-related proteins such as cyclin D1, Bcl-2 and Bax. These data suggest that PGG exerts anti-ER+ breast cancer effects. In this sense, our study provides new alternative therapies to treat breast cancer.

Dynamic production optimization involves continuous cycle of model-predictive control initiated at specified times to maximize production net present value (NPV) throughout the expected life of the reservoir. Re-evaluating predictive models using traditional methods is computationally expensive. The existing methods for updating production controls, do not take the inter-cycle correlation into account. But such information is valuable for boosting the problem-solving efficiency on the current cycle by utilizing the experience or knowledge extracted from the previous developed cycles. Originally, transfer learning algorithms are difficult to be implemented into the oil and gas industry, due to its high computational cost and random or unavailable learning samples. Therefore, we propose a new transfer learning based optimization framework for dynamic production optimization problems. First, domain adaptation learning (DAL) is used to represent data between two inter-cycles, to decrease the dissimilarity between them. Second, extended boundary constraints (EBC) is a technique used to embed the optimization problem into the learning samples during DAL stage. EBC reduces the burden on computational facilities and makes the algorithm suitable for production optimization. Third, a transfer component analysis (TCA) method is used to simplify the data representation and also extract the data correlation. Then, the extracted correlation is used to produce an effective population for MOEAs. The developed framework is incorporated into three well-known evolutionary algorithms, nondominated sorting genetic algorithm II (NSGAII), multiobjective particle swarm optimization (MOPSO), and multiobjective evolutionary algorithm based on decomposition (MOEA/D) and one single objective optimizer, particle swarm optimization (PSO) for NPV maximization and robust optimization respectively. The proposed method is tested on a series of dynamic benchmark problems dynamic and a practical case based on a three channel reservoir model. Results showed that the proposed method reduces the number of simulation calls needed to reach optimum control options when using population-based evolutionary algorithms. Also, using the proposed technique, a higher NPV and better convergence speed in comparison to their original evolutionary algorithms is achieved.

As one of the most fundamental configurations, the cavities with different geometric shapes are frequently encountered on various aerodynamic surfaces. In this paper, the direct simulation Monte Carlo (DSMC) which is one of the most successful particle simulation methods in treating rarefied gas dynamics is employed to investigate the flow characteristics of the cavity with a length-to-depth ratio of 1–8, a rearwall-to-frontwall height ratio of 0.5–2, and an inclined frontwall ranging from 20° to 70° for the free stream at a Mach number of 8 and an altitude of 60 km. The simulation results indicate that the shear layer and recirculation region within the cavity are changed greatly by varying length-to-depth ratio and the cavity is transformed into a closed type at the length-to-depth ratio of 6. For the cavity with a fixed length-to-depth ratio, the increase in rearwall height would push the shear layer away from cavity floor and hence increases the area of recirculation region. Conversely, the decrease in rearwall height would draw the shear layer into the interior of the cavity and finally the recirculation region would be split into two smaller and separated ones located at the left and right corners of the cavity respectively. A significant finding is that the criterion (i.e., length-to-depth ratio) for classifying the cavity type is not a constant but changes with freestream conditions. In addition, recirculation region(s) within the cavity can be eliminated completely by simultaneously inclining the frontwall and rearwall with an appropriate angle and meanwhile the shear layer is affected slightly.

The gradient Ni-Cu layer on nickel aluminum-bronze alloy was obtained by the thermal diffusion process. The corrosion resistance was improved due to the formation of protective film, consisted of Ni(OH)2 and Cu2O. Although the Ni-Cu layer exhibited local corrosion with uniform corrosion and pitting corrosion simultaneously during the immersion test, the pitting growth was depressed because of the gradient distribution of Ni and Cu. The relieving driving force for galvanic corrosion between outer passive layer and bare Ni-Cu in the pitting was the main factor, which was caused by the decreasing interface potential drop.

Microstructure evolution of the nickel-aluminum bronze alloy was studied by heat treatment, including annealing, normalizing, quenching and aging. The microstructure was refined and homogenized after quenching or quenching/aging at 450 ℃, which can eliminate selective phase corrosion effectively. Compared with the current production process, static corrosion rate reduced about 50%, due to the rapid formation of a protective film. In addition, cavitation corrosion rate reduced by a factor of 4.9 and 7.9 for the quenched and quenched/aged at 450 ℃ samples, respectively. This can be attributed to the improved hardness and weakened synergy between corrosion and mechanical attack.

A completely nickel-aluminum-copper (Ni-Al-Cu) layer was obtained through thermal diffusion process on a nickel-aluminum-bronze (NAB) substrate. The cumulative mass loss of the NAB alloy during the cavitation erosion tests was about 6.4 times and 5.5 times as large as that of the Ni-Al-Cu layer in distilled water and 3.5 wt% sodium chloride (NaCl), respectively. Electrochemical measurements under quiescence and cavitation erosion conditions were conducted to investigate the synergistic effects of cavitation erosion and corrosion. The results showed that the synergism had measurable effect on the cavitation erosion-corrosion process for both the NAB alloy and the Ni-Al-Cu layer. The total contribution of the cavitation erosion component including WE and WCIE was more than 80% and WE occupied the largest percentage. Thus, the improved cavitation erosion resistance of the Ni-Al-Cu layer was mainly due to mechanical factors, which implied a homogeneous and refined microstructure and the formation of hardened Ni3Al phase.

At present, many domestic total sulfur detection methods are accurate and reliable, but they are disadvantageous with a low detection frequency, a long detection period and delayed work. In this paper, the standards of the total sulfur content detection of natural gas were reviewed. Then, the standard methods and related techniques for on-line detection of the total sulfur contents in natural gas were discussed, and their principles were figured out. And finally, it was recommended to develop a domestic on-line detection standard method for sulfur compounds and the total sulfur contents in natural gas. It is concluded that on-line total sulfur content detection is the inevitable development trend in the future; and that there is neither methods nor standards at home available for on-line detection of the total sulfur contents in natural gas, so it is recommended to timely formulate a national standard correspondingly by referring to foreign standards, e.g. ASTM D7165-10(2015), ASTM D7166-10(2015) and ASTM D7493-2014. Keywords: Natural gas, Total sulfur content, On-line, Detection, National standard, International standard

Background Studies have shown that peak circulatory power (peak CircP; peak oxygen uptake × peak systolic blood pressure) is a variable predictor of prognosis in patients with left heart failure. It remains unknown whether peak CircP also predicts outcome in patients with idiopathic pulmonary arterial hypertension (IPAH). Methods Patients with newly diagnosed IPAH who underwent symptom-limited cardiopulmonary exercise testing (CPET) from 1 January 2011 to 1 January 2014 in Fuwai Hospital were prospectively enrolled and followed for up to 66 months for cardiac events (mortality and lung transplantation). Results One hundred forty patients with IPAH (104 female, mean age: 33 ± 11 years) were studied. During follow-up (mean: 42 ± 14 months), 24 patients died and 1 patient underwent lung transplantation. In the univariate analysis, peak oxygen uptake(VO2), oxygen uptake at anaerobic threshold, ventilation (VE)/carbon dioxide output (VCO2) slope, end-tidal partial pressure of carbon dioxide at anaerobic threshold, peak systolic blood pressure (SBP), the change of SBP, the change of heart rate, peak work rate, peak CircP, pulmonary vascular resistance, cardiac index and World Health Organization functional class were predictive of cardiac events (all P Conclusions Peak CircP, better than peak VO2 and VE/VCO2slope, was a strong predictor of cardiac events among exercise parameters in patients with IPAH.

As-cast nickel-aluminum bronze is prone to suffering selective phase corrosion in marine environments. To solve this problem, chromium was introduced via ion implantation to modify its surface microstructure, which was characterized by high-resolution transmission electron microscopy and auger electron spectroscopy. The corrosion behavior was studied by electrochemical measurements and salt spray test. It was found that the inherent selective phase corrosion in as-cast NAB was inhibited effectively when the implantation fluence was 5 × 1017 ions/cm2. The improved corrosion resistance after ion implantation was believed to stem from the rapid formation of a more protective film containing chromium oxides and hydroxides.

In this paper, we consider the N -person stag hunt game based on the two-person stag hunt game and assume that the payoff of successful stag hunters is larger than that of hare hunters, which is an important feature of the game, but is often ignored in previous works. We first study the evolutionary dynamics of cooperation for the game in infinite well-mixed populations by using the replicator equation, and find that there always exists only one interior equilibrium which is unstable. We then investigate the game in finite well-mixed populations by applying the Markov process, and observe that the equation of gradient of selection always has a unique interior root, which is consistent with the finding in infinite populations. We finally consider the game in structured populations by means of the pair approximation approach. We accordingly obtain the dynamical equation for weak selection to depict the evolutionary dynamics of cooperation in structured populations, and find that there still exists the case in which there is only one interior unstable equilibrium. Our work unveils the universal characteristics of cooperative dynamics in different scenarios for the N -person stag hunt game.

The surface modification of nickel-aluminum bronze (NAB) alloy was developed by thermal diffusion of Ni coating and the alloy matrix. A multilayer coating was designed with the gradient outer layer of the Ni-Cu solid solution and the inner layer of the Ni-Al-Cu intermetallic layer. The evolution of the multilayer was a diffusion controlled model. The enhanced corrosion resistance of the Ni-Cu layer could be found in the salt spray test, which exhibited uniform corrosion behavior compared with severe selective phase corrosion of the NAB alloy. Besides the gradient distribution of the components, it was also attributed to the formation of protective film, which mainly consisted of Ni(OH) 2 and Cu 2 O. It has been confirmed by electrochemical impedance spectroscopy (EIS) test and X-ray photoelectron spectroscopy (XPS) results.

Artificial sweeteners have been widely used as replacements for sugars in foods. Rapid determination of artificial sweeteners contained in various foods are highly desirable for the routine analysis. Here, we report a robust approach based on direct analysis in real time coupled with QTRAP mass spectrometry to screen and quantitate simultaneously seven artificial sweeteners, including aspartame, saccharin, acesulfame-K, neotame, sucralose, cyclamate and alitame in alcoholic drinks. The detection method merely involved a simple sample pretreatment process, with a good linearity, low limit of quantification, satisfied recovery and relative standard deviation for each target compound. More importantly, the approach is highly sensitive and accurate in monitoring the seven artificial sweeteners in whisky, Chinese liquors, beer and wines obtained from the supermarket. The results demonstrated that the approach described here could be suitable for large-scale application in routine quality control analysis of artificial sweeteners.

Efficient model inference is an important and practical issue in the deployment of deep neural networks on resource constraint platforms. Network quantization addresses this problem effectively by leveraging low-bit representation and arithmetic that could be conducted on dedicated embedded systems. In the previous works, the parameter bitwidth is set homogeneously and there is a trade-off between superior performance and aggressive compression. Actually, the stacked network layers, which are generally regarded as hierarchical feature extractors, contribute diversely to the overall performance. For a well-trained neural network, the feature distributions of different categories are organized gradually as the network propagates forward. Hence the capability requirement on the subsequent feature extractors is reduced. It indicates that the neurons in posterior layers could be assigned with lower bitwidth for quantized neural networks. Based on this observation, a simple yet effective mixed-precision quantized neural network with progressively decreasing bitwidth is proposed to improve the trade-off between accuracy and compression. Extensive experiments on typical network architectures and benchmark datasets demonstrate that the proposed method could achieve better or comparable results while reducing the memory space for quantized parameters by more than 25% in comparison with the homogeneous counterparts. In addition, the results also demonstrate that the higher-precision bottom layers could boost the 1-bit network performance appreciably due to a better preservation of the original image information while the lower-precision posterior layers contribute to the regularization of k − bit networks.