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Advances in microarray technologies have provided new platforms that are being widely adopted for use in the molecular microbiology laboratory. Microarrays are particularly well suited for diagnostics as they allow multiplexing, or the ability to test for multiple targets simultaneously from the same specimen. Microarray technologies commonly used for the detection and identification of microbial targets include both solid-state (planar) microarrays and bead-based suspension microarrays. Microarray methods have been applied to microbial detection, genotyping, and antimicrobial resistance gene detection. Microarrays can offer a panel approach to diagnose specific conditions, such as respiratory or gastrointestinal infections, and can discriminate isolates by genotype for epidemiological investigations. As more information becomes available on the genes involved in antimicrobial resistance, microarrays can assist in predicting susceptibility based on sequence detection in specific organisms. With further advances in automated microarray processing methods, data analysis software, and genotype-phenotype prediction algorithms, these tests will become even more useful as an addition to or replacement for conventional microbiology and antimicrobial susceptibility testing, allowing for more rapid and targeted therapy for infectious diseases.

A facile method for the selective synthesis of pillar[6]arenes has been developed. Due to a strong electron donor-acceptor interaction between the electron-deficient naphthalene diimide and a precursor for the pillararene, 1,4-diisobutoxy-2,5-bis(methoxymethyl) benzene, naphthalene diimide has been demonstrated to act as a template for selective synthesis of pillar[6]arene in a modest yield (30%).

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is a Chinese mega-science project to build the largest single dish radio telescope in Guizhou province, Southwest China. The construction of FAST will involve many kinds of analog and digital electrical equipments. The electrical equipments are potential threat to radio observation due to its ElectroMagnetic Interference (EMI) emission. The EMI should be safely shielded when FAST telescope operates. The shielding effectiveness of large shielding enclosures can be tested with two log periodic antennas, signal generator and spectrum analyzer. It is not suitable to test small shielding enclosure for that is not possible to put big antenna and signal generator inside. In this paper, an effective shielding effectiveness measurement system for the small shielding enclosure is introduced. This measurement system uses a frequency synthesizer of Valon Technology as signal generator which can measure the shielding effectiveness no more than 100dB in a frequency range of 23–6000MHz. Some of measurement results of shielding effectiveness are also presented.

After five and a half years construction, the main structure of Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been completed in September 2016. Meanwhile, a Radio Quiet Zone (RQZ) with radius 30 km has also been established. In order to evaluate the Radio Frequency Interference (RFI) influence from the mobile base stations within radius 5 km (the restriction zone of RQZ) around FAST, several measurements have been carried out when these stations were closed temperately. Comparing the RFI measurement results before and after the closure of these stations, the interference has been decreased more than 30 dB. Since November 1 2016, all the mobile base station within the restriction zone of FAST RQZ have be closed permanently to avoid the risk of the receiver saturation due to the interference coming from these stations.

A new method for viscosity measurement has been proposed based on the acousto-optic modulation on FBG. Theoretical analysis shows the bandwidth of the modulated FBG is related to the viscosity of liquid around the FBG. The experimental results show the sensitivity of the bandwidth as the viscosity increases from 1 mPa · s to 5.5 mPa · s.

This paper mainly discusses on what should be paid attention to when innovative ideas in bridge construction are put into practice through analyzing the achievements of China’s modern suspension bridge construction since the initiation of China’s reform and opening up to the outside world. In recent years, some new concepts have been put forward in stiffening beams, cable saddles, cable bent towers and other aspects of the suspension bridge during its development. Among them, some are innovative and useful indeed while some merely meaningless. Analyzing the innovations of suspension bridge has a guiding significance for China’s bridge construction in the future.

As one of the most popular reduction methods of large-scale data mining, simple random sampling usually causes the loss of small clusters when dealing with unevenly distributed datasets. A density biased sampling algorithm based on grid can avoid this problem. However, both the efficiency and the effectiveness are restricted by grid granularity. To overcome such drawbacks, a density biased sampling algorithm based on variable grid division was proposed. Each dimension of original dataset is divided according to the corresponding distribution. And the structure of the generated grid could match the distribution of original dataset. Experimental results demonstrate that density biased sampling based on variable grid division can achieve higher quality than simple random sampling and consumes less sampling time comparing with the density biased sampling algorithm based on grid.

Methionol (3-methylthio-1-propanol) is an important volatile sulphur-containing alcohol that may significantly impact food flavour. The purpose of this research is to investigate the bioproduction of methionol from L-methionine catabolism by Saccharomyces cerevisiae EC-1118. The biotransformation was carried out in coconut cream supplemented with L-methionine. Response surface methodology was applied for the optimization of fermentation conditions to achieve a high yield of methionol. A second-order polynomial model (R 2 = 0.912) was established based on the experimental data obtained in this study using multiple regression analysis. To obtain more accurate prediction results, a reduced quadratic model was obtained through backward elimination. Based on the reduced model, the optimal conditions for maximum methionol production were determined to be 0.30 % (w/v) of L-methionine, 0.10 % (w/v) of yeast extract and zero level of diammonium phosphate. Under these optimal conditions, a methionol concentration of 240.7 ± 17.4 μg/mL was achieved. This experimental result was in close agreement with the predicted value of 243.5 μg/mL, indicating that this model was adequate. These results indicate that fermentation by S. cerevisiae in L-methionine-supplemented coconut cream medium is an effective method for the production of methionol. Large-scale fermentation trials are needed to provide valuable information for industrial production.

The kinematics of superluminal components in blazar 3C 454.3 are studied. Nine components are included: superluminal knots R1, R2, R3, R4, A, B, C and D (from Britzen et al. 2013) and C4 (from Pauliny-Toth 1998). We find that their kinematics derived from VLBI observations can be consistently interpreted in terms of a jet precession scenario with a period of about 14.5 yr. We discuss the model fits of their trajectory, distance from the core and apparent velocity. We show that the bulk Lorentz factor (in the range 4 to 15) derived for these components does not have any dependence on the phase of the precession (or position angle for ejection). The Lense-Thirring effect is assumed to interpret the precession of the jet nozzle. The results obtained for blazar 3C 454.3 are only suggestive. They are not unique and have yet to be tested, but they might be useful for understanding the kinematics of superluminal components in blazars and for disentangling different mechanisms and factors.

Based on the PBA construction method of Changchun Liberation Road station metro line No.2, in order to get the optimization of construction sequence of six pilot tunnels, we use numerical simulation method and finite element software MIDAS GTS to establish the construction model of the station pilot tunnel. After comparing four excavation methods of the surface subsidence, we come to a conclusion that first up then down and first side then middle is the optimal excavation scheme. At the same time, we make models to analysis the necessity of making advance support before pilot tunnel construction. Pipe shed and small duct grouting pre support is very significant to the control of the subsidence of ground surface and vault.

The characteristics of process mineralogy of the some lead-zinc mine were studied with scanning electron microscope, optics microscopes，and x-ray diffraction. The species of lead minerals and zinc minerals and the chemical composition of the minerals were analyzed. The liberations at different grinding finenesses and the particle sizes of the minerals had been also determined. The phase shape of lead and zinc in the ore was also analyzed. The behaviors of various minerals and mineralogical factors affecting the flotation had been explained clearly. The investigation results were favorable to reasonable selection of flotation parameters and would provide theoretical guidance to lead-zinc separation.

The characteristics of process mineralogy of some pyrite cinders were studied with optics microscopes, scanning electron microscope, and x-ray diffraction. The chemical composition and the phase composition of the pyrite cinders were analyzed. The occurrence and chemical phase analysis of molybdenum of iron, copper, and gold were also studied. The behaviors of various minerals and mineralogical factors affecting the separation had been explained clearly. The investigation results were favorable to reasonable selection of technological process.

An on-site dispersive liquid liquid microextraction base on the solidification of switchable solvent has been developed as a simple, rapid and eco-friendly sample extraction method for the fast determination of pyrethroid insecticides in aqueous samples using high-performance liquid chromatography with ultraviolet detection. In this extraction method, medium-chain saturated fatty acids (n≥10), which can rapidly solidify at low temperatures (

The scale and complexity of search space are important factors deciding the solving difficulty of an optimization problem. The information of solution space may lead searching to optimal solutions. Based on this, an algorithm for combinatorial optimization is proposed. This algorithm makes use of the good solutions found by intelligent algorithms, contracts the search space and partitions it into one or several optimal regions by backbones of combinatorial optimization solutions. And optimization of small-scale problems is carried out in optimal regions. Statistical analysis is not necessary before or through the solving process in this algorithm, and solution information is used to estimate the landscape of search space, which enhances the speed of solving and solution quality. The algorithm breaks a new path for solving combinatorial optimization problems, and the results of experiments also testify its efficiency.

Food traceability is a support tool for preventing and improving food safety problems. The purpose of food traceability is to collect the flow and transformation information of food-related materials in the food chains. When faced with a food safety crisis, we can find the source of the problem and track the flow of products from the information, and effectively carry out food recalls. In this paper, the status of food traceability in China is deeply analyzed from the laws, regulations, standards, traceability techniques and systems construction, and validity of internal and external traceability in food chains is assessed retrospectively. Then some recommendations for the further development of China's food traceability are proposed.

In China, quality credit is an important part of the social credit system, and evaluation of quality credit is the key to the construction of quality credit system. In this paper, on the basis of product quality credit factor analysis and evaluation index construction, a hybrid strategy of three stages is proposed according to the different nature of indicators. The emphasis is put on intelligent evaluation model based on statistics and artificial neural network. According to the results of experimental verification, this credit evaluation method shows a high accuracy for the evaluation of quality credit.

An active reflector is one of the three main innovations incorporated in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change the position of the 2225 nodes through the connected down tied cables. For each different tracking process of the telescope, more than 1/3 of these 2225 actuators must be in operation to tune the parabolic aperture accurately and meet the surface error restriction. This means that some of these actuators are inevitably located within the main beam of the receiver, and Electromagnetic Interference (EMI) from the actuators must be mitigated to ensure the scientific output of the telescope. Based on the threshold level of interference detrimental to radio astronomy described in ITU-R Recommendation RA. 769 and EMI measurements, the shielding efficiency (SE) requirement for each actuator is set to be 80 dB in the frequency range from 70 MHz to 3 GHz. Therefore, Electromagnetic Compatibility (EMC) was taken into account in the actuator design by measures such as power line filters, optical fibers, shielding enclosures and other structural measures. In 2015, all the actuators had been installed at the FAST site. Till now, no apparent EMI from the actuators has been detected by the receiver, which demonstrates the effectiveness of these EMC measures.

FAST, Five hundred meter Aperture Spherical Telescope, is the Chinese effort for the international project SKA, Square Kilometer Array. An innovative engineering concept and design pave a new road to realizing huge single dish in the most effective way. Three outstanding features of the telescope are the unique karst depressions as the sites, the active main reflector which corrects spherical aberration on the ground to achieve full polarization and wide band without involving complex feed system, and the light focus cabin driven by cables and servomechanism plus a parallel robot as secondary adjustable system to carry the most precise parts of the receivers. Besides a general coverage of those critical technologies involved in FAST concept, the progresses in demonstrating model being constructed at the Miyun Radio Observatory of the NAOC is introduced. Being the most sensitive radio telescope, FAST will enable astronomers to jumpstart many of science goals, for example, the natural hydrogen line surveying in distant galaxies, looking for the first generation of shining objects, hearing the possible signal from other civilizations, etc. Among these subjects, the most striking one could be pulsar study. Large scale survey by FAST will not only improve the statistics of the pulsar population, but also may offer us a good fortune to pick up more of the most exotic, even unknown types like a sub-millisecond pulsar or a neutron star – black hole binary as the telescope is put into operation.

There is a limitation on the field of view (FOV) of a large aperture radio telescope: the FOV decreases with increasing resolution and sensitivity of the telescope and the greater the aperture, the smaller the FOV. In order to enlarge the FOV, we may place several discrete feeds on the focal plane of the telescope. When these feeds work simultaneously, the FOV and therefore the operating efficiency of the telescope will be increased by several times. A disadvantage of this solution is the discontinuous character of the resulting FOV. Moreover, the number of feeds mounted on the focal plane is restricted by the F/D ratio of the telescope. We investigate in this paper an innovative technique for realization of simultaneous and continuous large FOV for the FAST (Five-hundred-meter Aperture Spherical radio Telescope). The proposed new feed is a dense focal-plane array of microstrip antenna elements, the so called Vivaldi antennas. The electro-magnetic properties of the Vivaldi element and Vivaldi array are briefly introduced, which are essential for this application. The focal-field distributions (FFD) of FAST are simulated by using the software package GRASP8 for different illuminations. The simulation results give important information for the layout design of the array, especially for the weighting system of the Vivaldi array. A preliminary configuration of the array structure is suggested, and the illumination patterns are estimated. Finally, some remarks on the feasibility of applying the Vivaldi array to FAST are made.

The hydrolysis of ether bonds is a potentially green method for using plants as a source of chemicals. Although the arylalkyl ether anisole can be hydrolyzed to phenol and methanol in the presence of aluminum chloride, the method has the disadvantage that it produces large amounts of alumina as by product. Since the carbon atoms of ethers that are directly bound to the oxygen have carbonium ion character, nucleophilic attack is a possible route to inducing cleavage of these carbon–oxygen bonds. The hydrolysis of the carbon–oxygen bond in ethers is induced by molybdate as nucleophile, or by aluminum phosphate in combination with ultrasound. High yields are obtained with epoxides, and significantly lower yields with trimethylene oxide and tetrahydrofuran. The molybdate or phosphate oxoanion acts as the nucleophile. Calculations have been carried out to determine patterns affecting the enthalpy of the hydrolysis of ethers to alcohols. These show that the reaction is close to being thermoneutral, but that both ether hydrolysis and ether ammonolysis are enthalpically favored, especially for ethers that have sterically bulky or fluorinated substituents.

The synthesis and characterization of ruthenium(II) complexes, [Ru(cyclam)(bqdi)] x ZnCl(4) (1 x ZnCl(4); cyclam = 1,4,8,11-tetraazacyclotetradecane, bqdi = o-benzoquinonediimine), [Ru(cyclam)(nqdi)] x (ClO(4))(2) (2 x (ClO(4))(2); nqdi = 2,3-naphthoquinonediimine), and [Ru(cyclam)(phi)] x (ClO(4))(2) (3 x (ClO(4))(2); phi = 9,10-phenanthroquinonediimine), are described. The DNA binding properties and biological activity of the Ru(II) complexes were studied by various biophysical and cytological techniques. As expected, only 3 showed significant binding with DNA. The thermodynamic profile of the binding of 3 and DNA was constructed by analyzing the experimental data of absorption titration and UV melting studies with the McGhee equation, van't Hoff's equation, and the Gibbs-Helmholtz equation. Compound 3 binds double-stranded DNA with a binding constant of 5.0 x 10(4) M(-1) at 20 degrees C, and the binding mode of the complex to DNA was proved to be intercalative. Cytotoxicity and induced type of cell death of 1-3 were also investigated. Basically, metal complexes with ligands of molecular shape closely related to the structure of DNA are more likely to bind DNA and possess higher toxicity.

Context. The search for periodic features in flux variability and kinematics of superluminal components in blazars is capable of providing significant clues for the understanding of the physical processes in their central engines (black-hole/accretion-disk systems), especially concerning the formation and structure of their relativistic jets and radiation mechanisms.Aims. The jet swing on parsec-scales and the change of the ejection position angle of the superluminal components with time in the quasar B1308+326 (z = 0.997) are investigated as quasi-periodic behaviors.Methods. A previously published precessing jet nozzle model is applied to model the source kinematics and a possible jet precession period is found.Results. Based on the model fitting of the kinematics for a subset of components, it is shown that their kinematics, including the shape of the inner trajectories and the motion of the components, could be well fitted in terms of the precessing jet nozzle model and a precession period of ~16.9 ± 0.3 yr is derived. Different precession mechanisms are discussed and compared.Conclusions. It is shown that the swing of the ejection position angle of the superluminal knots observed in B1308+326 may be due to the orbital motion of a putative supermassive black hole binary in its nucleus. Some relevant parameters of the binary model are estimated. We also discuss the spin-induced precession mechanism in the single black hole scenario and an estimate for the spin of the Kerr black hole is obtained.

A novel demodulation method for Sagnac loop interferometer based sensor has been proposed and demonstrated, by unwrapping the phase changes with birefringence interrogation. A temperature sensor based on Sagnac loop interferometer has been used to verify the feasibility of the proposed method. Several tests with 40 °C temperature range have been accomplished with a great linearity of 0.9996 in full range. The proposed scheme is universal for all Sagnac loop interferometer based sensors and it has unlimited linear measurable range which overwhelming the conventional demodulation method with peak/dip tracing. Furthermore, the influence of the wavelength sampling interval and wavelength span on the demodulation error has been discussed in this work. The proposed interrogation method has a great significance for Sagnac loop interferometer sensor and it might greatly enhance the availability of this type of sensors in practical application.

To address the issue of evolutionary data classification, we propose an evolving swarm classification model. It treats each class as an ant colony carrying different type of pheromone. The ant colonies send their members to propagate their unique pheromone on the unlabeled instances, so as to label them for member recruitment. Meanwhile, the unlabeled instances are treated as unlabeled ants, which also have their preferences for joining one of those labeled colonies. We call it homing feedback, and integrate it into the pheromone update process. Afterwards, the natural selection process is carried out to keep a balance between the member recruitment and the ant colony size maintenance. Sufficient experiments demonstrate that our algorithm is effective in the real-world evolutionary classification applications.

Constrained clustering uses pairwise constraints, i.e., pairs of data that belong to the same or different clusters, to indicate the user-desired contents. In this paper, we propose a new constrained clustering algorithm, which can utilize both must-link and cannot-link constraints. It first adaptively determines the influence range of each constrained data, and then performs clustering on the expanded range of data. The promising experiments on the real-world data sets demonstrate the effectiveness of our method.

The precise analysis of mineral abundance is a key difficulty in hyperspectral remote sensing research. In the present paper, based on linear spectral mixture model, the derivative of ratio spectroscopy (DRS) was introduced for spectral unmixing of visible to short-wave infrared (Vis-SWIR; 0.4 - 2.5 microm) reflectance data. The mixtures of different proportions of plaster and allochite were analyzed to estimate the accuracy of the spectral unmixing model based on DRS. For the best 5 strong linear bands, the Pearson correlation coefficient (PCC) of the abundances and the actual abundances were higher than 99.9%, while the root mean square error (RMSE) is less than 2.2%. The result shows that the new spectral unmixing model based on DRS is simple, of rigorous mathematical proof, and highly precise. It has a great potential in high-precision quantitative analysis of spectral mixture with fixed endmembers.

qnrD, unlike other qnr genes, is mainly located on small nonconjugative plasmids. We investigated the presence of qnrD among 1,373 Enterobacteriaceae isolates in China. Twelve qnrD-positive strains were detected, and all were nonsusceptible to fluoroquinolones. The complete sequence of plasmids showed that the qnrD determinants were located on two plasmids with a respective size of ~4.2 and 2.7 k-bp. Interestingly, the identification of qnrD in this study revealed the highest prevalence of Proteeae among Enterobacteriaceae identified.

We describe a computer simulation technique for generating the monochromatic light diffraction from arbitrary apertures. For the Fresnel diffraction of rectangular and circular apertures, a simple form of equation for the light intensity distribution is derived. A method for displaying the color of monochromatic light on the monitor is presented. On this basis, we implement the diffraction simulation of white light formed via mixing three monochromatic lights of λ=700,546.1,435.8 nm with the same ratio in the RGB color space of CIE1931 system.

Food Traceability is regarded as a critical capability to enable and improve food safety both in public and private sector. However, the market practice to food traceability system (FTS) is not perfect. In lots of cases, the inefficient traceability supply is attributed to the gap of public's demand on higher traceability level and private companies' insufficient supply as expected. The fact is that public sector is less informed about quality and safety attributes of food than private sector, but private sector does not have adequate incentive to cover the gap. In order to explore how to mitigate the gap, this paper reviewed the key concepts and adoption history of FTS, compared the different incentives of each role in the ecosystem to adopt FTS, and analyzed the impacts of those incentives on the system design. Then a conceptual framework is developed to guide the FTS design with insight in the architecture design, functionality collection and business model design. Finally, theoretical and practical implications are discussed and future research opportunities are suggested.

One hundred two pathogenic Escherichia coli isolates from diseased pigs were analyzed for serotypes, virulence genes, antimicrobial susceptibility, and the molecular basis of phenicol resistance. Of these 102 E. coli isolates, 101 were typeable and belonged to 27 different O serogroups. However, 69% of these isolates belonged to one of the following eight serogroups: O8, O54, O64, O65, O92, O108, O119, and O120. Serogroups O8 (23%) and O64 (10%) were the most prevalent among typeable isolates. High-resistance phenotypes were observed in all the isolates, with the majority displaying resistance to chloramphenicol (89%), streptomycin (83%), enrofloxacin (78%), and doxycycline (60%). The chloramphenicol resistance genes cat1, cat2, and cmlA were detected in 58%, 49%, and 65%, respectively, of the chloramphenicol-resistant isolates. The floR gene was detected in 57% of the florfenicol-resistant isolates and in 52% of chloramphenicol-resistant isolates. Pulsed-field gel electrophoresis showed that the 32 floR-positive isolates with florfenicol minimum inhibitory concentration ≥ 8 μg mL⁻¹ belonged to 25 different pulsed-field gel electrophoresis profiles, indicating the spread of floR among swine pathogenic E. coli isolates.

In this paper a improving relay selection scheme based on the coalitional game is designed in the multi-user wireless networks. We firstly analyze the model of mutil-user cooperation networks. Then a brief introduction of the coalition concepts is given. In our strategy, source node and relay nodes constitute a coalition in order to increase the transmission rate and lower the BER of system. One coalition contains only one source. However, the relays that we consider can be the members of different coalitions. So how many coalitions a node is in takes into consideration in the scheme. Finally, we present the simulation results of the relay selection scheme.

The title compounds, {Cu[CH3C6H4N(CH2COO)2]}-2H2O (I) and {Cu[CH3OC6H4N(CH2COO)2]}-2H2O (II) have been prepared and crystal structures determined. The crystallographic data are as follows: (I) Mr = 320.8, monoclinic, P21/c, a = 12.523(2), b = 7.481(2), c = 15.126(4) A, β = 111.85(2)°, V=1314.9A3, Z = 4, δ(CuKa)=1.5410 A, F(000) = 660, room temperature, R = 0.052 for 1952 observed reflections with I > 3[sgrave](I); (II) Mr = 336.39, monoclinic, P21/c, a = 11.452(2), b = 7.595(2), c = 15.416(2) A, β = 101.60(1)°, V = 1313.4 A3, Z = 4, δ(MoKα) = 0.7107 A, F(000) = 692, room temperature, R = 0.052 for 1091 observed reflections with 1 > 3[sgrave](I). The Cu atom is five coordinate (N(1), O(1), 0(2), O(10) and O(20)) in (I) to form a distorted square pyramid in which O(20) is at the apical site. The Cu(1)-O(20) bond is much longer than the basal bond lengths. In (II), the Cu atom is six coordinate (N(1), 0(1), 0(2), O(10), O(20) and O(01)) in the form of an unsymmetrical and elongated tetragonal bipyra...

In our studies, qualitative (scanning electron microscope) and semi-quantitative (modified crystal violet staining method) methods had been used to evaluate Escherichia coli biofilm-forming ability. Broth microdilution method and enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR) were performed to study E. coli drug resistance pattern and genetic typing. Based on the results above, we studied the correlation between biofilm-forming ability phenotype, drug resistance pattern and genetic typing in E. coli. Real-time qPCR (qRT-PCR) was used to reveal mRNA expression level of E. coli biofilm related multiple antibiotics resistance genes (acrA, agn43, csgA, csgD, ompF and pgaA) under different concentrations of four aminoglycoside pressures. Our results showed that: (i) forty-nine out of 64 strains of E. coli (76.56%) showed significant production of biofilm and most of them performed weak biofilm-forming ability; (ii) ERIC-PCR showed that there was significant correlation between biofilm-forming ability and genotype; while there was weak correlation between biofilm-forming ability and drug resistance patterns based upon the results of semi-quantitative method and antibiotics susceptibility test; (iii) qRT-PCR revealed mRNA expression of acrA, agn43, csgA, csgD, ompF and pgaA genes changed accordingly by stimulation of different concentrations of four aminoglycosides.

As one of the most popular data reduction category for large scale data mining, simple random sampling (SRS) often leads to the loss of small clusters when dealing with unevenly distributed datasets. A density biased sampling algorithm based on grid can avoid the problem. However, the grid division granularity has an influence on the efficiency and effectiveness of the algorithm. To overcome the drawback, a variable grid density biased sampling is proposed to deal with large scale unevenly distributed datasets. However, the efficiency is restricted by dimensionality. Aiming at this, an efficient density biased sampling algorithm is proposed for large high-dimensional datasets. Firstly, an efficient feature selection method is designed to obtain the feature subsets. Secondly, the variable grid division is executed in the selected feature subsets. Finally, the sample is obtained from the grid space. Synthetic datasets and UCI datasets, tested in our experiments, reveal that the proposed algorithm can achieve higher quality than SRS. Meanwhile, the proposed algorithm consumes less sampling time comparing with density biased sampling algorithm based on grid and density biased sampling algorithm based on variable grid division.