金精矿超声波强化硝酸预氧化提金研究

本文提出了常压低温下对原生金矿预处量的一种新方法 ,对于含硫较高的原生矿 ,采用超声波强化硝酸预氧化处理工艺 ,处理后的氧化渣采用氰化浸出 ,金的浸出率同硝酸直接氧化后氰化浸出相比 ,有显著提高 ,该方法氧化时间短 ,对设备要求低 ,具有一定的生产价值。

Characterization of Energy_Transduction in Thermal Pretreated Chloroplast from Spinach

Characterization of energy-transduction on die chloroplast thylakoid membranes from spinach (Spinacia oleracca L.) after thermal pretreatment was investigated. The related reactions of energy-transduction in chloroplasts were seriously affected by thermal pretreatment. The results were obtained as following: (1) The rate of cyclic photophosphorylation declined when the pretreatment temperature increased in the range of 25 to 45 degreesC. (2) The thermal pretreatment led to a decrease of the activity of thylakoid membrane-bounded ATPase. (3) Proton uptake of chloroplasts acid the fluorescence quenching of 9-aminoacridine (9-AA) in thylakoid membrane decreased after the thermal pretreatment, but addition of dicyclohexylcarbodiimide (DCCD) could partially restore the fluorescence quenching of 9-AA. (4) Both the rates of fast phase in electrochroism absorption change at 515 nm and the millisecond delayed light emission (ms-DLE) of chloroplast showed a progressive decrease upon raising the temperature of pretreatment. (5) Immunbloting analysis showed that the thermal pretreatment caused the changes of protein content and the electrophoresis mobility of thylakoid membrane-bound ATPase and its alpha -subunit. (6) If the temperature of pretreatment were higher than 33 degreesC, oxygen uptake of PS I -mediated in the samples was rapidly inhibited, but addition of sinapine into the reaction medium could partially restore the ability of oxygen uptake in the samples. These results are briefly discussed in relation to the change of permeability of thylakoid membranes, the dissociation of coupling factor complex as well as accumulation of the radicals in the thylakoid membranes after thermal pretreatment.

Co evolutions for WC-Co with different Co contents during pretreatment and HFCVD diamond film growth processes

Systematical researches were accomplished on WC-Co with different Co contents(6%,10%and 12%,mass fraction).Based on the XPS and EDX,from orthogonal pretreatment experiments,it is indicated that the acid concentration,the time of the acid pretreatment and the original Co content have significant influences on the Co-removal depth(D).Moreover,the specimen temperature,original Co content and Co-removal depth dependences of the Co evolution in nucleation,heating(in pure H2 atmosphere)and growth experiments were discussed,and mechanisms of Co evolutions were summarized,providing sufficient theoretical bases for the deposition of high-quality diamond films on WC-Co substrates,especially Co-rich WC-Co substrates.It is proven that the Co-rich substrate often presents rapid Co diffusion.The high substrate temperature can promote the Co diffusion in the pretreated substrate,while acts as a Co-etching process for the untreated substrates.It is finally found that the appropriate Co-removal depth for the WC-12%Co substrate is 8-9μm.

Application of Tertiary Amine Cationic Polyacrylamide with High Cationic Degree in Salt-free Dyeing of Reactive Dyes

Tertiary amine cationic polyacrylamide with high cationization degree was used as a new cationic agent to pretreat cotton with dip-pad-bake method. The obtained cationic cotton was dyed with reactive dyes in the ab-sence of electrolyte. The effects of the characteristics of the cationic agent and the pretreatment conditions on dye-ability of reactive dye were investigated. The results showed that the fixation and K/S values of the reactive dyes on the cationic cotton were improved compared with those on the untreated one in the presence of salt. Tests on fast-ness properties of the dyed cotton and fabric quality of the pretreated cotton were carried out and the results showed that wash and rub fastness of the salt-free dyeing were both satisfactory. And anti-crease property,tensile and tear strength,and handling of the cationic cotton were also good compared with that of the untreated one.

Estimation of As and Cu Contamination in Agricultural Soils Around a Mining Area by Reflectance Spectroscopy:A Case Study

Concentrations of Iron (Fe), As, and Cu in soil samples from the fields near the Baoshan Mine in Hunan Province, China, were analyzed and soil spectral reflectance was measured with an ASD FieldSpec FR spectroradiometer (Analytical Spectral Devices, Inc., USA) under laboratory condition. Partial least square regression (PLSR) models were constructed for predicting soil metal concentrations. The data pre-processing methods, first and second derivatives (FD and SD), baseline correction (BC), standard normal variate (SNV), multiplicative scatter correction (MSC), and continuum removal (CR), were used for the spectral reflectance data pretreatments. Then, the prediction results were evaluated by relative root mean square error (RRMSE) and coefficients of determination (R 2 ). According to the criteria of minimal RRMSE and maximal R 2 , the PLSR models with the FD pretreatment (RRMSE = 0.24, R 2 = 0.61), SNV pretreatment (RRMSE = 0.08, R 2 = 0.78), and BC-pretreatment (RRMSE = 0.20, R 2 = 0.41) were considered as the final models for predicting As, Fe, and Cu, respectively. Wavebands at around 460, 1 400, 1 900, and 2 200 nm were selected as important spectral variables to construct final models. In conclusion, concentrations of heavy metals in contaminated soils could be indirectly assessed by soil spectra according to the correlation between the spectrally featureless components and Fe; therefore, spectral reflectance would be an alternative tool for monitoring soil heavy metals contamination.

Low-dose steroid pretreatment ameliorates the transient impairment of liver regeneration

AIM： To determine if liver regeneration （LR） could be dis- turbed following radiofrequency （RF） ablation and whe- ther modification of LR by steroid administration occurs.

An adaptive preprocessing algorithm for low bitrate video coding

At low bitrate, all block discrete cosine transform (BDCT) based video coding algorithms suffer from visible blocking and ringing artifacts in the reconstructed images because the quantization is too coarse and high frequency DCT coefficients are inclined to be quantized to zeros. Preprocessing algorithms can enhance coding efficiency and thus reduce the likelihood of blocking artifacts and ringing artifacts generated in the video coding process by applying a low-pass filter before video encoding to remove some relatively insignificant high frequent components. In this paper, we introduce a new adaptive preprocessing algo- rithm, which employs an improved bilateral filter to provide adaptive edge-preserving low-pass filtering which is adjusted ac- cording to the quantization parameters. Whether at low or high bit rate, the preprocessing can provide proper filtering to make the video encoder more efficient and have better reconstructed image quality. Experimental results demonstrate that our proposed preprocessing algorithm can significantly improve both subjective and objective quality.

Some Peculiarities of the Preprocessing of Spectral Data and Images

Remotely sensed spectral data and images are acquired under significant additional effects accompanying their major formation process, which greatly determine measurement accuracy. In order to be used in subsequent quantitative analysis and assessment, this data should be subject to preliminary processing aiming to improve its accuracy and credibility. The paper considers some major problems related with preliminary processing of remotely sensed spectral data and images. The major factors are analyzed, which affect the occurrence of data noise or uncertainties and the methods for reduction or removal thereof. Assessment is made of the extent to which available equipment and technologies may help reduce measurement errors.

Effect of magnetite content on Bond work index and preconditioning: Case study on Chadormalu iron ore mine

Grinding is one of the most costly operations in the mechanical breaking and mining.Determination of the breakage characteristics and preconditioning is important to increase the grinding efficiency.Investigations of the seismic,mechanical and breakage properties of iron oxides are very important parameters for investigating the rock fragmentation by blasting and comminution processes in iron ore mines.In this paper,at first,geomechanical and seismic properties of the oxide ores(magnetite and hematite)in the Chadormalu iron ore mine were studied.The results showed that the percentage of magnetite has a direct relationship with uniaxial compressive strength,tensile strength and P and S wave’s velocities and has an inverse relationship with Poisson ratio and porosity.Moreover,to study breakage and preconditioning characteristics in the iron ores,two samples with different magnetite percents were blasted by detonation cord.The results showed that with higher percentage of magnetite,the number of fractures induced by blasting increased.Bond work index and magnetite percent were investigated in the 430 blasts in the mine.This investigation not only confirmed the small scale blasting results,but also showed that increasing the magnetite percent up to 50%noticeably reduces Bond work index and energy consumption in the grinding process.Also,the relationship between muck pile fragmentation and magnetite percentage were studied for several blasts that had the same blast pattern parameters and similar geology conditions.These results also confirmed precedents conclusions regarding magnetite percent and preconditioning relationship.

In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata,the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress measurements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evident 150 m ahead of the longwall face and abutment loading reached a maximum increase of about7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The forward abutment load determined from the stress change monitoring is consistent with the weight of overburden strata overhanging the goaf indicated by subsidence monitoring.

Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia(2%, 4%, and 6%, dry matter) and three moisture contents(30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates(50, 65, and 80 g·L-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g-1(based on per unit volatile solids loaded), with shorter digestion time(T80) of 25 days at the loading rate of 65 g·L-1compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively,while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

An Integrated Approach to Oscillation Propagation Identification and Source Locating in Process Multi-loop Systems

An integrated method for identifying the propagation of multi-loop process oscillations and their source location is proposed in this paper. Oscillatory process loop variables are automatically selected based on the component-related ratio index and a mixing matrix, both of which are obtained in data preprocessing by spectral independent component analysis. The complex causality among oscillatory process variables is then revealed by Granger causality test and is visualized in the form of causality diagram. The simplification of causal connectivity in the diagram is performed according to the understanding of process knowledge and the final simplest causality diagram, which represents the main oscillation propagation paths, is achieved by the automated cutting-off thresh-old search, with which less significant causality pathways are filtered out. The source of the oscillation disturbance can be identified intuitively through the final causality diagram. Both simulated and real plant data tests are presented to demonstrate the effectiveness and feasibility of the proposed method.

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability(RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.

Effects of High CO_2 Pretreatment on the Quality of Fresh-Cut Potatoes

Effects of short-term high CO_2 pretreatment on quality of fresh-cut potatoes were studied. Potatoes were treated under 90% CO_2 for 18 h, peeled, cut, dipped in 1% ascorbic acid or distilled water for 3 min, packed in polyethylene bags and stored for 12 d at 4 ℃. Non-treated potatoes were used as the control. High CO2 pretreatments ensured maintenance of a high level of CO_2 in headspace of packages containing fresh-cut potatoes. Both the growth of total aerobic bacteria in initial stages of post-cut storage and browning index of the cut surface were lower in high CO_2 treated cut potato. Anti-browning effect of high CO_2 pretreatment was decreased when applied in combination with ascorbic acid. Soluble solids, pH, titratable acidity and flesh firmness of fresh-cut potatoes were not affected by high CO_2 treatment. Therefore, high CO_2 treatment before slicing could be effective method to maintain quality of flesh-cut potatoes.

Removal of jamming using independent component analysis in non-cooperative passive detection system

Due to electronic jamming transmitted by hostile electromc jamming equtpmcnts tional jamming from other illuminating sources in the complex electromagnetic environment, the per- formance of non-cooperative passive detection systems may degrade it significantly. To solve the problem, a receiving frame with multiple channels for signal preprocessing is designed and a theoret- ical analysis to the received signals in the complex electromagnetic environment is provided. Fur- thermore, a scheme for jamming removal using independent component analysis is proposed. Simula- tion results demonstrate the proposed scheme appears as a very appealing solution for removal of jam- ming and an approximate lOdB signal to distortion ratio over traditional schemes is obtained.

Pre-treatment to Enhance Biogas Yield from Pulp and Paper Mill Sludge

The purpose of this work was to study the potential to enhance biogas production from pulp and paper mill sludge by the use of thermal pre-treatment in combination with chemical pre-treatment. Biogas from waste is a renewable fuel with very low emissions during combustion. To further reduce the use of fossil fuels, more biogas substrates are necessary. Pulp and paper mill sludge is a large untapped reservoir of potential biogas. Pulp and paper mill sludge was collected from a mill that produces both pulp and paper and has a modified waste activated sludge system as part of its wastewater treatment. Pre-treatments were chosen heat （70 ~C or 140℃） combined with either acid （pH 2 or pH 4） or base （pH 9 or pH 11, obtained with Ca（OH）2 or NaOH）. Biogas potential was tested by anaerobic digestion batch assays under mesophilic conditions. All pre-treatments were tested in six replicates. Biogas volume was measured with a gas-tight syringe and methane concentration was measured with a gas chromatograph. The methane yield from sludge subjected to thermal pre-treatment at 70℃ did not differ from the untreated sludge, but thermal pre-treatment at 140℃ had a positive effect. Within the 70℃ thermal pre-treatment group, the pH 2 acid was the most successful chemical pre-treatment, and Ca（OH）2 pH 9 had the least effect with no measurable improvement in methane yield. For the 140 ℃ thermal pre-treatment group, acid and NaOH impacted methane production negatively, while the Ca（OH）2-treated sludge did not differ from sludge with no chemical pre-treatment. In conclusion, thermal pre-treatment at 70℃ showed no effect, whereas, pre-treatment at 140℃ improved methane yield with 170%, and for this sludge additional, chemical pre-treatments are unnecessary.

Multi-neighboring grids schemes for solving PDE eigen-problems

Instead of most existing postprocessing schemes, a new preprocessing approach, called multi- neighboring grids （MNG）, is proposed for solving PDE eigen-problems on an existing grid G（A）. The linear or multi-linear element, based on box-splines, are taken as the first stage Khuh -λh/1Mh/1Uh. In this paper, the j-th stage neighboring-grid scheme is defined as Khuh λh/j Mh/j Uh = λh/j Mh/j Uh , where gh ：- Mh/j-1 Kh/1 and Mhuh is to be found as a better mass distribution over the j-th stage neighboring-grid G（/k）, and Kh/1 can be seen as an expansion of Kh on the j-th neighboring-grid with respect to the （j - 1）-th mass distribution Mh_l. It is shown that for an ODE model eigen-problem, the j-th stage scheme with 2j-th order B-spline basis can reach 2j-th order accuracy and even （2j ＋ 2）-th order accuracy by perturbing the mass matrix. The argument can be extended to high dimensions with separable variable cases. For Laplace eigen-problems with some 2-D and 3-D structured uniform grids, some 2j-th order schemes are presented for j ≤ 3.

Comprehensive Approach for Porous Materials Analysis Using a Dedicated Preprocessing Tool for Mass and Heat Transfer Modeling

The paper presents a comprehensive, newly developed software – poROSE(poROus materials examination SoftwarE) for the qualitative and quantitative assessment of porous materials and analysis methodologies developed by the authors as a solution for emerging challenges. A low porosity rock sample was analyzed and thanks to the developed and implemented methodologies in poROSE software, the main geometrical properties were calculated. A tool was also used in preprocessing part of the computational analysis to prepare a geometrical representation of the porous material. The basic functions as elimination of blind pores in the geometrical model were completed and the geometrical model was exported for CFD software. As a result, it was possible to carry out calculations of the basic properties of the analyzed porous material sample. The developed tool allows to carry out quantitative and qualitative analysis to determine the most important properties characterized porous materials. In presented tool the input data can be images from X-ray computed tomography(CT), scanning electron microscope(SEM) or focused ion beam with scanning electron microscope(FIB-SEM) in grey level. A geometric model developed in the proper format can be used as an input to modeling mass, momentum and heat transfer, as well as, in strength or thermo-strength analysis of any porous materials. In this example, thermal analysis was carried out on the skeleton of rock sample. Moreover, thermal conductivity was estimated using empirical equations.