商业轮转印刷机故障排除两例

1.印品上有墨粒、纸毛黏附故障现象:有一色组印刷印章时,印章圆弧线上有直径0.5mm 至2mm 不等的墨粒及纸毛黏附现象。经检查,橡皮布与印版上油墨,纸粉堆积较厚,橡皮布对应纸边的位置纸粉白边严重。初步判断是纸质疏松所致。洗擦橡皮布及印版后,放缓机速印刷,问题并未完全解决,约一小时后同一问题再次出现。于是判断主要原因在油墨。用墨刀掏墨槽发觉油墨流动性极差,

Preparation of CulnS2 Thin Film Using Sulfides Nanoparticle Precursor Ink

A low cost spin coating route of fabricating CuInS2 polycrystalline thin films by reactive sintering method was put forward. The ink for spin coating was optimized by pre-reducing the precursor powders in hydrogen, which turned the nanoparticle precursor powders from mixed sulfides into a mixture of CuInS2 and Cu-In metal alloys. The results of scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman spectra showed that this optimization could highly improve the performance of CuInS2 polycrystalline thin films, including higher packing density, less impurity phases, and better quality. The energy gap of optimized CuInS2 thin film was determined to be about 1.45 eV by absorption spectroscopy measurement.

High Performance Ultraviolet Photodetector Fabricated with ZnO Nanoparticles-graphene Hybrid Structures

Ultraviolet （UV） photodetector constructed by ZnO material has attracted intense research and commercial interest. However, its photoresistivity and photoresonse are still unsatisfied. Herein, we report a novel method to assemble ZnO nanoparticles （NPs） onto the reduced graphite oxide （RGO） sheet by simple hydrothermal process without any surfactant. It is found that the high-quality crystallized ZnO NPs with the average diameter of 5 nm are well dispersed on the RGO surface, and the density of ZnO NPs can be readily controlled by the concentration of the precursor. The photodetector fabricated with this ZnO NPs- RGO hybrid structure demonstrates an excellent photoresponse for the UV irradiation. The results make this hybrid especially suitable as a novel material for the design and fabrication of high performance UV photodector.

Influence of graphite particle size and its shape on performance of carbon composite bipolar plate

Bipolar plates for proton exchange membrane fuel cell (PEMFC) where polymer is used as binder and graphite is used as electric filler were prepared by means of compression molding technology. Study on the effects of graphite particle size and shape on the bipolar plate performance, such as electrical conductivity, strength, etc. showed that with decrease of graphite particle size, bulk electrical conductivity and thermometric conductivity decreased, but that flexural strength was enhanced. After spherical graphite occurrence in flake-like form, the flexural strength of the bipolar plate was enhanced, electrical conductivity increased but thermal conductivity decreased in direction paralleling pressure direction, and both electrical conductivity and thermometric conductivity reduced in direction perpendicular to pressure direction.

Preparation of low-temperature sintered high conductivity inks based on nanosilver self-assembled on surface of graphene

Finer nanoplates of silver are prepared by self-assembly on the surface of graphene,and the low-temperature sintered high conductivity ink containing the silver nanoplates is prepared.Most importantly,graphene is added to the solution before the chemical reduction reaction occurs.Firstly,it is found that silver nanoplates have self-assembly phenomenon on the surface of graphene.Secondly,the Ag nano hexagonal platelets(AgNHPs)with small particle sizes(10 nm),narrow distribution and good dispersion are prepared.Especially,smaller sizes(10 nm)and narrower particle size distribution of AgNHPs particles can be easily controlled by using this process.Finally,the conductivity of the ink is excellent.For example,when the printed patterns were sintering at 150℃,the resistivity of the ink(GE:0.15 g/L)reached the minimum value of 2.2×10^-6 cm.And the resistivity value was 3.7×10^-6Ωcm,when it was sintered at 100℃ for 30 min.The conductive ink prepared can be used for the field of printing electronics as ink-jet printing ink.

Tribological and corrosion behavior of PEO coatings with graphite nanoparticles on AZ91 and AZ80 magnesium alloys

The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation（PEO） coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances of the obtained coatings were investigated. A solution that contained both phosphates and silicates was used as electrolyte. Moreover, two different PEO treatment times were studied. The corrosion resistance was analyzed with potentiodynamic polarization and EIS tests; the wear resistance was investigated with a flat on ring tribometer. The results were related to the morphology, microstructure, elemental composition and thickness evaluated with SEM analysis. The presence of the graphite nanoparticles increased the thickness, produced a densification of the coating and sealed the pores on the surface, thus improving both the corrosion and wear resistance. The increase in the corrosion and wear resistances was more evident for AZ91 than for AZ80 due to the higher aluminum content.

Microstructures and wear properties of graphite and Al_2O_3 reinforced AZ91D-Cex composites

The magnesium matrix composites reinforced by graphite particles and Al2O3 short fibers were fabricated by squeeze-infiltration technique.The additions dispersed uniformly and no agglomeration and casting defect were observed.The microstructures and wear properties of the composites with different Ce contents of 0,0.4%,0.8%and 1.0%,respectively,were investigated.Especially,the effect of Ce on the properties was discussed.The results reveal that Ce enriches around the boundaries of graphite particles and forms Al3Ce phase with Al.The addition of Ce refines the microstructures of the composites.With the increase of Ce content,the grain size becomes smaller and the wear resistance of the composite is improved.At low load,the composites have similar worn surface.At high load,the composite with 1.0%Ce has the best wear resistance due to the existence of Al3Ce phase.The Al3Ce phase improves the thermal stability of the matrix so the graphite particles can keep intact,which can still work as lubricant. At low load,the wear mechanism is abrasive wear and oxidation wear.At high load,the wear mechanism changes to delamination wear for all the composites.

Effect of graphite content on wear property of graphite/Al_2O_3/Mg-9Al-1Zn-0.8Ce composites

Using squeeze-infiltration technique, Mg-9Al-1Zn-0.8Ce composite reinforced by graphite particles and Al2O3 short fibers was fabricated. The reinforcing phases combined closely with the matrix and no agglomeration was observed. The microstructure, hardness and wear property of the composites with the graphite content of 5%, 10%, 15% and 20% were investigated, respectively. The results reveal that Ce tends to enrich around the boundaries of graphite particles and Al2O3 short fibers, and forms Al3Ce phase. When the graphite content increases to 20%, the grain size becomes small. Moreover, with increasing the graphite content, the microhardness of the composites decreases but the wear resistance increases. The graphite which works as lubricant during dry sliding process decreases the wear loss. At low load, the wear mechanism of the composite is mainly abrasive wear and oxidation wear; at high load, except that the composite with 20% graphite is still with abrasive wear and oxidation wear, the wear mechanism of other composites changes to delamination wear.

Gas-Phase Deposited Plasmonic Nanoparticles Supported on 3D-Graphene/Nickel Foam for Highly SERS Detection

In this work, we proposed a novel three-dimensional (3D) plasmonic nanostructure based on porous graphene/nickel foam (GNF) and gas-phase deposited Ag nanoparticles (NPs). Ag NPs with high density were directly deposited on the surface of 3D GNF by performing a novel cluster beam deposition approach. In comparison with traditional Ag substrate (SiO2/Ag), such hot-spots enriched 3D nanostructure showed extremely high electromag-netic field enhancement under incident light irradiation which could be used as a sensitive chemical sensor based on surface enhanced Raman scattering (SERS). The experimental results demonstrated that the proposed nanostructure showed superior SERS performance in terms of Raman signal reproducibility and sensitivity for the probe molecules. 3D full-wave simulation showed that the enhanced SERS performance in this 3D hierarchical plasmonic nanostructure was mainly obtained from the hot-spots between Ag NPs and the near-field coupling between Ag NPs and GNF sca olds. This work can provide a novel assembled SERS substrate as a SERS-based chemical sensor in practical applications.

Ambient Air Particulate PM2.5 Concentrations and Identification of Source Categories at Chihuahua, Mexico

Suspended particles in the air are pollutants formed by diverse materials and sizes. As determined in multiple studies, particulate matter equal to or less than 2.5 μrn also called breathable fraction is the one that penetrates the inferior respiratory system. The present study shows the results of a sampling campaign of particulate matter PM25 through 12 months at 3 sites： C33 （Clinic 33）, CIM （CIMAV） and A VA （Avalos） at Chihuahua, Mexico. The aim of this study was to determine the temporary concentrations of PM25, the concentration of metallic elements： Al, As, Co, Cu, Sb, Se, Fe, Mg, Mn, Ni, Pb and Zn, as well as their possible sources. The three sites had the same trend in the time, where in autumn and winter the higher concentrations were found. The yearly averages on sites C33, CIM, and AVA were 9.91, 12.74 and 21.67 μg·m^-3, respectively, finding that AVA site overpasses the standard of 15 μg·m^-3. The application of factor analysis to the data allowed to identify four source categories： crustal, related with Al-Co-Fe-Mg-Mn, vehicular, related with： As-Cu-Sb-Se; mixed, related with： As-Cu-Sb-Se-Pb-Zn and industrial related with Ni-Pb.

Catalytic Performance of Graphite Oxide Supported Au Nanoparticles in Aerobic Oxidation of Benzyl Alcohol： Support Effect

Various Au/GO catalysts were prepared by depositing Au nanoparticles on thermally- and chemically-treated graphite oxide （GO） supports using a sol-immobilization method. The surface chemistry and structure of GO supports were characterized by a series of analytical techniques including X-ray photoelectron spectroscopy, temperature-programmed desorption and Raman spectroscopy. The results show that thermal and chemical treatments have large influence on the presence of surface oxygenated groups and the crystalline structure of GO supports. A strong support effect was observed on the catalytic activity of Au/GO catalysts in the liquid phase aerobic oxidation of benzyl alcohol. Compared to the amount and the type of surface oxygen functional groups, the ordered structure of GO supports may play a more important role in determining the catalytic performance of Au/GO catalysts.

Sono-assisted preparation of magnetic ferroferric oxide/graphene oxide nanoparticles and application on dye removal

A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.

Catalytic Performance of Carbon Materials Supported Pd Nanoparticles in Selective Hydrogenation of Acetylene

Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction.

Composite Ni-Nanodiamond Coating Deposited by Electroless Method

The work in this study is focused on investigation of composite nickel coatings. The coatings were deposited on ductile cast iron samples of different composition by electroless method EFTTOM NICKEL with addition of strengthening nanodiamond particles （2-4 nm）, The samples were prepared by casting and austempering. The microstructure, microhardness and wear resistance of the coatings were investigated. The thickness of the coatings was also determined （8-10μm）. Metallographic analyses, SEM （scanning electron microscopic） investigation, microhardness measurements by knoop method, wear resistance tests were carried out. The coatings with and without heat treatment at 290℃, 6 h were tested. Duplication of microhardness value and improvement of the coating＇s properties of heat treated coatings were observed.

Light-induced ZnO/Ag/rGO bactericidal photocatalyst with synergistic effect of sustained release of silver ions and enhanced reactive oxygen species

Silver nanoparticles (Ag NPs) can effectively address the issue of antibiotic-resistant bacterial infections to reduce the potential toxicity of Ag NPs. Although challenging, it is, therefore, necessary to achieve the sustainable release of Ag+ ions from a finite amount of Ag NPs. This study aims at designing an efficient and benign antimicrobial silver-based ternary composite composed of photocatalysis zinc oxide (ZnO) and reduced graphene oxide (rGO) as a carrier, in which the reactive oxygen species (ROS) excited from ZnO and Ag+ ions released from the Ag NPs cooperate to realize an effective antibacterial activity against E. coli and S. aureus. The constant effective bacterial performance of the ternary photocatalyst with minimum Ag content can be attributed to the increase in the available quantity of ROS, which results from the enhanced separation efficiency of the photogenerated carriers. The proposed system notably realized the long-term sustainable release of Ag+ ions with low concentration for 30 days when compared with an equivalent amount of silver nitrate. Moreover, the use of the composite prevents biotoxicity and silver wastage, and imparts enhanced stability to the long-lasting antibacterial efficacy.

Size Distribution of Particulate Matter of Metals in Urban Aerosols, Comarca Lagunera, Mexico

This paper has demonstrated that there is great variation in the size range and chemical composition of metalliferous PM （particulate matter） present within Comarca Lagunera, M6xico due to the physiography of the terrain together the intense vehicular traffic, unpaved roads, cement and lime plants, marble quarries, brick plants, and the largest smelter of non-ferrous material in Latin America. Cascade impactor PM samples from six size ranges： 〈 0.49 μm, 0.49-0.9 μm, 0.9-1.5μm, 1.5-3.0 p.m, 3.0-7.2 μm and 7.2-10 μm were collected from inside two stacks within G6mez Palacios and Torreon cities. ICP-AES （inductively coupled plasma-atomic emission spectrometry） analysis on collected Whatman fiberglass filters demonstrates that the PM are matrices mostly constituted of carbonates and silicates with abundant fine metalliferous particles. The metals with the most concentrations averaged over all size ranges were Cu, Fe, Mn, Ni, Pb and Ti. The size distributions of metals detected in this work have been plotted as normalized histogram concentration of each size fraction, the total concentration, and the aerodynamic particle diameter, which is a useful method for comparing the contributions of coarse and fine particles to pollutant concentrations.

Optimization of friction and wear behaviour of Al-Si_3N_4 nano composite and Al-Gr-Si_3N_4 hybrid composite under dry sliding conditions

The tribological behaviour of gravity die stir cast LM6alloy with graphite(Gr)and silicon nitride nanoparticles was investigated.Al?Gr?Si3N4hybrid composite,Al?Si3N4nanocomposite and Al?Gr nanocomposites were separately fabricated to investigate their frictional and wear characteristics under dry sliding conditions.EDS was used to ensure the uniform presence of nano Si3N4and graphite in the cast.L9orthogonal array method was chosen to conduct the experiments to study the effect of different applied loads(20,30and40N)and sliding distances(1,2and3km).The results showed that the respective wear rate and coefficient of friction(COF)decreased by25%and15%for hybrid composite when compared with those of Al?Si3N4nanocomposite whereas the wear rate and COF of Al?Gr was found to be very minimal.The micro Vickers hardness of the hybrid composite was14%more than that of the simple nanocomposite and there was not much notable variation for Al?Gr and Al?Si3N4nanocomposite materials.Scanning electron microscope was used to analyze the worn surface and subsurface,from which it was noted that the predominant wear mechanisms observed were abrasive for nanocomposite and both abrasive and adhesive mechanism for hybrid composite.Analysis of variance(ANOVA)and F-test were used to check the validity model and to determine the significant parameters affecting the wear rates.

Heat Transfer Performance of a Multi-heat Pipe Using Graphene Oxide/Water Nanofluid

A multi-heat pipe is a device for heat transmission. It is composed of a heating section, a cooling section and an adiabatic section. The heating and cooling sections are the same and both are connected by four circular parallel tubes. This experimental study is performed to investigate heat transfer performance of a multi-heat pipe in the vertical orientation using pure water and GO （graphene oxide）/water nanofluid. GO/water nanofluids were synthesized by the modified Hummers method with 0.05%, 0.1%, 0.15%, and 0.2% volume concentrations. The thermal performance has been investigated with varying heat flux in the range of 10-30 W and 100% fill charge ratio. Wall temperature, thermal resistance, and heat transfer coefficient of the heat pipe are measured and compared with those for the heat pipe using pure water. The experimental results show that the evaporator wall temperature with GO nanofluid is lower than that of the base fluid. Also, the heat pipe that charged with nanofluids showed lower thermal resistance compared with pure water. Heat transfer enhancement is caused by suspended nanoparticles and is pronounced with the increase in particle volume fraction.

Cu nanoparticles supported on graphitic carbon nitride as an efficient electrocatalyst for oxygen reduction reaction

High active and cost‐effective electrocatalysts for the oxygen reduction reaction(ORR)are essential components of renewable energy technologies,such as fuel cells and metal/air batteries.Herein,we propose that ORR active Cu/graphitic carbon nitride(Cu/g‐CN)electrocatalyst can be prepared via a facile hydrothermal reaction in the present of the ionic liquid(IL)bis(1‐hexadecyl‐3‐methylimidazolium)tetrachlorocuprate[(C16mim)2CuCl4]and protonated g‐CN.The as‐prepared Cu/g‐CN showed an impressive ORR catalytic activity that a99mV positive shift of the onset potential and2times kinetic current density can be clearly observed,comparing with the pure g‐CN.In addition,the Cu/g‐CN revealed better stability and methanol tolerance than commercial Pt/C(HiSPECTM3000,20%).Therefore,the proposed Cu/g‐CN,as the inexpensive and efficient ORR electrocatalyst,would be a potential candidate for application in fuel cells.

Effects of graphene nanoplates on microstructures and mechanical properties of NSA-TIG welded AZ31 magnesium alloy joints

The effects of graphene nanoplates(GNPs)on the microstructures and mechanical properties of nanoparticlesstrengthening activating tungsten inert gas arc welding(NSA-TIG)welded AZ31magnesium alloy joints were investigated.It wasfound that compared with those of activating TIG(A-TIG),and obvious refinement ofα-Mg grains was achieved and the finestα-Mggrains of fusion zone of NSA-TIG joints were obtained in the welded joints with TiO2+GNPs flux coating.In addition,thepenetrations of joints coated by TiO2+GNPs flux were similar to those coated by the TiO2+SiCp flux.However,the welded jointswith TiO2+GNPs flux coating showed better mechanical properties(i.e.,ultimate tensile strength and microhardness)than those withTiO2+SiCp flux coating.Moreover,the generation of necking only occurred in the welded joints with TiO2+GNPs flux.