An insight on the mechanism of efficient leaching of vanadium from vanadium shale induced by microwave-generated hot spots

Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.

Experimental research and application of cold cutting to hot stamping parts based on multiphase microstructure

Among the bottlenecks that hinder the improvement of the production efficiency of hot stamping are high strength and difficulty in edge cutting and hole punching.Starting from the preparation of hot stamping multiphase microstructure materials,this paper developed a plate quenching die system with controllable surface temperature and prepared four types of hot stamping plates with different martensite volume fractions.Then,straight edge cold cutting experiments were performed to study the influence of cutting clearance and cutting force on fracture quality.The results show that the bright zone is the largest when the cutting clearance is 0.14 mm,and the cutting experience coefficient of the hot stamping sheet with each martensite volume fraction is obtained when the cutting clearance is 0.14 mm.The research results of this paper were applied to the production of hot stamping parts.

一种消除hot spot现象的LED背光设计

随着高亮度LED晶片、导光板成型技术、光学薄膜(反射膜、散射膜、增亮膜)等制作技术的发展,加上不断创新的LED背光模组光学系统设计,以及LED背光市场的巨大需求,大大推动了LED背光技术水平不断向前发展。这里设计了一种消除hot spot现象的背光设计。结果可知:达到设计效果的改进关键仅是在导光板的入光面上贴上一条有微棱镜结构的膜片,从而使入射至导光板的光束角度变大,达到良好的均匀光效果。让增加相邻LED间距而不出现hot spot现象成为可能,这一研究对于消除hot spot所带来的均匀性过差问题具有一定的意义。

Efficacy and adverse events of cold vs hot polypectomy: A meta-analysis

AIM: To compare previously reported randomized controlled studies(RCTs) of cold and hot polypectomy, we systematically reviewed and clarify the utility of cold polypectomy over hot with respect to efficacy and adverse events.METHODS: A meta-analysis was conducted to evaluate the predominance of cold and hot polypectomy for removing colon polyps. Published articles and abstracts from worldwide conferences were searched using the keywords "cold polypectomy". RCTs that compared either or both the effects or adverse events of cold polypectomy with those of hot polypectomy were collected. The patients' demographics, endoscopic procedures, No. of examined lesions, lesion size, macroscopic and histologic findings, rates of incomplete resection, bleeding amount, perforation, and length of procedure were extracted from each study. A forest plot analysis was used to verify the relative strength of the effects and adverse events of each procedure. A funnel plot was generated to assess the possibility of publication bias.RESULTS: Ultimately, six RCTs were selected. No significant differences were noted in the average lesion size(less than 10 mm) between the cold and hot polypectomy groups in each study. Further, the rates of complete resection and adverse events, including delayed bleeding, did not differ markedly between cold and hot polypectomy. The average procedural time in the cold polypectomy group was significantly shorter than in the hot polypectomy group.CONCLUSION: Cold polypectomy is a time-saving procedure for removing small polyps with markedly similar curability and safety to hot polypectomy.

SYSTEMATIC AND DYNAMIC PROPERTIES OF CASTING HOT SPOT

The variation of casting hot spot with proceeding of solidification andcomponents of casting-mold system is studied by the technique of numerical simulation ofsolidification. The result shows that the thickest part of casting is not exactly the last part ofsolidification in the casting, while the last part of solidification is not exactly casting hot spotat the early stage of solidification. The location, size, shape and number of casting hot spotchange with geomitric, physical and technological factors of the casting-mold system such asthickness of the casting secondary wall and with the passage of time in the course of thesolidification. The former is known as the systematic property of hot spot and the latter, dynamicproperty. Only when the properties of hot spot are grasped completely and accurately, can it be fedmore effectively. By doing so, not only sound castings can be obtained, but also riser efficiencycan be improved.

Comment on 'Efficacy and adverse events of cold vs hot polypectomy: A meta-analysis'

This is a comment on a meta-analysis of published studies comparing cold vs hot polypectomy. We believe that the conclusion of this meta-analysis that "cold polypectomy is a time-saving procedure for removing small polyps with markedly similar curability and safety to hot polypectomy" needs more rigorous evidence.

改善侧导光LED背光Hot Spot现象的导光板设计

就改善侧导光LED背光Hot Spot现象,文章提出了一种解决办法:在导光板入光侧对应LED的位置进行处理,让其形成一个非球面的凹面,可以使LED发出的光发散,从而减轻或消除Hot Spot现象。

Chemical Properties of Pectin from Industry Hot and Cold Break Tomato Products

Tomato processing includes a break step, which involves rapid heating of freshly chopped tomatoes to >90°C for hot break, or 60°C to 77°C for cold break. Pectolytic enzyme deactivation is believed to be the key element in the hot break step;therefore, pectin content of different products should be qualitatively distinct. The objective of this study was to investigate the effect of hot break versus cold break on the cell-wall pectin of tomato. Cell-wall pectin from hot and cold break tomato products was isolated and analyzed for carbohydrate composition, degree of polymerization, and degree of esterification. The results showed no observable differences in the cell-wall pectin isolated from the two products, indicating that there was no significant pectolytic breakdown of the tomato in the cold break product, and the pectin might not, by itself, contribute to the differences in the final product viscosity resulting from the two processing techniques.

The Hot Spots in Cereal Rusts and Powdery Mildew Research

Cereal crops, including wheat, barley, oats, rye, etc., are the major sources of calories and proteins for most of the people in the world as well as in China. Cereal rusts and powdery mildews are very important diseases occurred on the cereal crops, which caused yield losses at 5-10% in general and even more than 30% while severe epidemics occurred. In recent years, with the global climate change, change of cultivation system and evolution of the pathogens, the world is facing great challenges caused by cereal diseases.

Removal of diminutive colorectal polyps: A prospective randomized clinical trial between cold snare polypectomy and hot forceps biopsy

AIM To compare the efficacy and safety of cold snare polypectomy(CSP) and hot forceps biopsy(HFB) for diminutive colorectal polyps.METHODS This prospective, randomized single-center clinical trial included consecutive patients ≥ 20 years of age with diminutive colorectal polyps 3-5 mm from December 2014 to October 2015. The primary outcome measures were en-bloc resection(endoscopic evaluation) and complete resection rates(pathological evaluation). The secondary outcome measures were the immediate bleeding or immediate perforation rate after polypectomy, delayed bleeding or delayed perforation rate after polypectomy, use of clipping for bleeding or perforation, and polyp retrieval rate. Prophylactic clipping after polyp removal wasn't routinely performed.RESULTS Two hundred eight patients were randomized into the CSP(102), HFB(106) and 283 polyps were evaluated(CSP: 148, HFB: 135). The en-bloc resection rate was significantly higher with CSP than with HFB [99.3%(147/148) vs 80.0%(108/135), P < 0.0001]. The complete resection rate was significantly higher with CSP than with HFB [80.4%(119/148) vs 47.4%(64/135), P < 0.0001]. The immediate bleeding rate was similar between the groups [8.6%(13/148) vs 8.1%(11/135), P = 1.000], and endoscopic hemostasis with hemoclips was successful in all cases. No cases of perforation or delayed bleeding occurred. The rate of severe tissue injury to the pathological specimen was higher HFB than CSP [52.6%(71/135) vs 1.3%(2/148), P < 0.0001]. Polyp retrieval failure was encountered CSP(7), HFB(2).CONCLUSION CSP is more effective than HFB for resecting diminutive polyps. Further long-term follow-up study is required.

Regional Variability of Climate Change Hot-Spots in East Asia

The regional climate change index （RCCI） is employed to investigate hot-spots under 21st century global warming over East Asia. The RCCI is calculated on a 1-degree resolution grid from the ensemble of CMIP3 simulations for the B1, AIB, and A2 IPCC emission scenarios. The RCCI over East Asia exhibits marked sub-regional variability. Five sub-regional hot-spots are identified over the area of investigation： three in the northern regions （Northeast China, Mongolia, and Northwest China）, one in eastern China, and one over the Tibetan Plateau. Contributions from different factors to the RCCI are discussed for the sub-regions. Analysis of the temporal evolution of the hot-spots throughout the 21st century shows different speeds of response time to global warming for the different sub-regions. Hot-spots firstly emerge in Northwest China and Mongolia. The Northeast China hot-spot becomes evident by the mid of the 21st century and it is the most prominent by the end of the century. While hot-spots are generally evident in all the 5 sub-regions for the A1B and A2 scenarios, only the Tibetan Plateau and Northwest China hot-spots emerge in the B1 scenario, which has the lowest greenhouse gas （GHG） concentrations. Our analysis indicates that subregional hot-spots show a rather complex spatial and temporal dependency on the GHG concentration and on the different factors contributing to the RCCI.

Internal oxidation of hot-rolled ultra-high strength steel and its effect on the surface quality of cold-rolled sheets

In this study,the scale and internal oxidation of hot-rolled ultra-high strength steel sheets were characterized.It was found that both the formation of the scale and the internal oxidation of Si and Mn depended on the coiling temperature and position of the steel sample on the strip coil.At a relatively high coiling temperature,a large amount of internal oxidation was observed on the samples cut from the middle of the coil.The depth of the internal oxidation zone exceeded 10 μm and a thin iron layer covering the scale was observed in some cases.Pickling and cold-rolling experiments were conducted on selected samples.Scale pickling was found to be greatly delayed by the formation of an iron layer,which frequently resulted in under-pickled defects.In addition,pickling of the entire internal oxidation zone was difficult,except at the grain boundaries,where the degree of internal Si and Mn oxidation was enriched.The surface of the cold-rolled steel sheet was ruined by the remaining oxidation zone in the subsurface of the pickled steel.The internal oxidation of hot-rolled ultra-high strength steel must be precisely controlled to improve the subsequent surface quality of cold-rolled steel.

Hot Spot in Materials with Structural Defects under High Shear Loading Rates

The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation.

Detection of spatial hot spots and variation for the neon flying squid Ommastrephes bartramii resources in the northwest Pacific Ocean

With the increasing effects of global climate change and fishing activities,the spatial distribution of the neon flying squid(Ommastrephes bartramii) is changing in the traditional fishing ground of 150°-160°E and 38°-45°N in the northwest Pacific Ocean.This research aims to identify the spatial hot and cold spots(i.e.spatial clusters) of O.bartramii to reveal its spatial structure using commercial fishery data from2007 to 2010 collected by Chinese mainland squid-j igging fleets.A relatively strongly-clustered distribution for O.bartramii was observed using an exploratory spatial data analysis(ESDA) method.The results show two hot spots and one cold spot in 2007 while only one hot and one cold spots were identified each year from2008 to 2010.The hot and cold spots in 2007 occupied 8.2%and 5.6%of the study area,respectively;these percentages for hot and cold spot areas were 5.8%and 3.1%in 2008,10.2%and 2.9%in 2009,and 16.4%and 11.9%in 2010,respectively.Nearly half(>45%) of the squid from 2007 to 2009 reported by Chinese fleets were caught in hot spot areas while this percentage reached its peak at 68.8%in 2010,indicating that the hot spot areas are central fishing grounds.A further change analysis shows the area centered at156°E/43.5°N was persistent as a hot spot over the whole period from 2007 to 2010.Furthermore,the hot spots were mainly identified in areas with sea surface temperature(SST) in the range of 15-20℃ around warm Kuroshio Currents as well as with the chlorophyll-a(chl-a) concentration above 0.3 mg/m^3.The outcome of this research improves our understanding of spatiotemporal hotspots and its variation for O.bartramii and is useful for sustainable exploitation,assessment,and management of this squid.

THE COLD AND HOT DAMAGES TO THE CITRUS IN THE THREE GORGES AREA OF THE CHANGJIANG RIVER

ＴＨＥＣＯＬＤＡＮＤＨＯＴＤＡＭＡＧＥＳＴＯＴＨＥＣＩＴＲＵＳＩＮＴＨＥＴＨＲＥＥＧＯＲＧＥＳＡＲＥＡＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲＣｈｅｎＺｈｅｎｇｈｏｎｇ（陈正洪）；ＹａｎｇＨｏｎｇｑｉｎｇ（杨红青）；ＮｉＧｕｏｇｕ（倪国裕）（Ａｇｒｏ...

THE GEOTHERMAL PULSE OF HOT-SPOT AND ITS DISPERSION PROCESS OVER CHINA-INDIA-BURMA AND CHANGE OF SHORT-TERM CLIMATE

The great gorge of Yarlung Zangbo river is a hot\|spot over earth has been proved by the gravity, geomagnetic, geological, geothermal heat and atmospheric data. Some substances often surge from mantle to the earth surface, which process is not constant and has obvious pulse, characterized by ground temperature over hot\|spot region where is a apparent positive relation in correlation map of the variations of Zedang’s temperature (at 3 2m) in stations over China from 1965 to 1992. It can bring more precipitation here. Out of from the hot spot, there are positive and negative axes around the hot\|spot and to arrange in circular waves with same distance. The average distant of the axes is about 820km, which prove the pulse propagation would infect the distribution of summer precipitation in China. In the hot\|spot region, the geothermal heat pulse propagation has preference direction. So, it has obvious contribution for summer precipitation in South Ch ina.

Ventilated Double Skin Facades in Hot-Summer and Cold-Winter Zones in China

Double-skin facades(DSF)are a technique developed for colder climates,so few people think about whether or not it can also be used for hot-summer and cold-winter zones in China.After analyzing the problems of using DSF for hot-summer zones,this paper explored on the possibility of applying DSF in hot-summer and cold-winter zones in China.The main existing research methods for DSF were also collected and commented.If properly managed,the ventilated DSF with controlled shading devices can be used even in hot summer in China.

Analysis of causes and influence factors of small black spot defects in hot-dip galvanized pure Zn products

In this study,the factors affecting the formation of small black spot defects on the surface of a hot-dip galvanized pure zinc strip are analyzed. These defects are primarily formed w hen the iron-aluminum inhibition layer is incompletely formed or fails to form or when foreign matter adheres to the surface or embeds in the zinc layer.The defects can be reduced by controlling the cleanliness and activity of the strip base before coating,regulating the zinc pot process parameters,and ensuring the cleanliness of the passline and workshop.

STUDY ON LOCATION OF HOT SPOT AT TUBE WALL FOR FIRED CYLINDRICAL FURNACE COMBUSTION

Based on the analysis of heat radiation intensity from flame, a new mathematical model ofthe tube-wall temperatmp of heated tubes is developed by taking down-fired, upright-tube cylindricalfurnace for example. The proposed mathematical model can be employed to indicate both the positionand size of the hot spot at fire-facing wall of heated tube of combustion chamber, and is characteristicof simplicity and efficiency If coupled with thermoelectric couple or infrared viewer, the presentedlocation method of combustion hot spot can offer engineers very valuable proposal to keep furnacerunning more safely The same is true for any other type of tubular furnaces.

The mechanism of hot crack formation in Ti-6Al-4V during cold crucible continuous casting

Hot crack is one of common defects in castings, which often results in failure of castings. This work studies the formation of hot crack during cold crucible continuous casting by means of experiments and theoretical analysis. The results show that hot crack occurs on the surface and in the circumference of ingots, where the solidified shell and the solidification front meet each other. The tendency of hot cracking decreases with the increase of withdrawal velocities in some extent. The hot crack is caused mainly by the friction force between the shell and the crucible inner wall, and it takes place when the stress resulting from friction exceeds the tensile strength of the shell. The factors of μ_m, η_t, η_s and η_m, affecting hot cracks are analyzed and verified. In order to decrease the tendency of hot cracks, technical parameters should be optimized by decreasing μ_m, η_t, η_s and η_m.