麦达佩克铜选矿厂通过改进浮选过程提高铜回收的技术指标

该厂原选别流程南斯拉夫麦达佩克铜选矿厂分两期建成,目前每年可处理1100万吨贫铜矿石。第一期工程(一号浮选车间)于1961年投产,年处理能力为360万吨矿石。第二期工程又建了两个浮选车间(即二号和三号浮选车间),它们分     

An Exact Solution for Heat Transfer of a Jet Co-Axially Impinging on a Rotating Disk and Its Comparisons with Stagnation Point Experiments

IntroductionJet impingement is a widely used high-efficiencytechnique fOr cooling rotating disks, which are end-wallsurfaces of gas turbine rotors, comPuter disk drives etc.Fluid f'low, heat trallsfer and geometric arrangement inthe case of a single round jet impinging co-axially in anorthogonal mode on a rotatng disk are characterized byFig. l.Many peculiarihes of fluid fIow and heat transfer ofreal impinging jets under comPlicated conditions(different system geometry, impinging flow proper…     

Assessment of medical occupational radiation doses in Costa Rica

Participation of the University of Costa Rica (UCR) in activities in an IAEA Regional Project RLA/9/066 through training, equipment and expert missions, has enabled to setting up of a national personal monitoring laboratory. Since 2007, the UCR has been in charge of monitoring around 1800 medical radiation workers of the Social Security System. Individual external doses are measured with thermoluminescent dosemeter using a Harshaw 6600 Plus reader. The service has accreditation with ISO/IEC 17025:2005. Distribution of monitored medical personnel is as follows: 83 % in diagnostic radiology, 6 % in nuclear medicine and 6 % in radiotherapy. Preliminary values for the 75 percentile of annual H(p)(10) in mSv are: radiology 0.37; interventional radiology 0.41; radiotherapy 0.53 and nuclear medicine 1.55. The service provided by the UCR in a steady and reliable way can help to implement actions to limit the doses received by the medical workers and optimise their radiation protection programs.     

Photosensitized degradation in water of the phenolic pesticides bromoxynil and dichlorophen in the presence of riboflavin, as a model of their natural photodecomposition in the environment

Within the context of environmentally friendly methods for the elimination of surface-water pollutants, the photodegradation of the phenolic pesticides bromoxynil (BXN) and dichlorophen (DCP) under simulated natural conditions has been studied. The work was done in the presence of the visible-light absorber photosensitizer riboflavin (Rf), usually present in trace quantities in natural waters. Under aerobic conditions, an efficient photooxidation of both pesticides was observed. The relatively intricate photochemical mechanism involves pesticide and oxygen consumption and, to a lesser extent, Rf degradation. The kinetic and mechanistic study supports that both H(2)O(2) and singlet molecular oxygen, O(2)((1)Δ(g)), are involved in the process. Kinetic data for the O(2)((1)Δ(g))-mediated oxidation indicate that BXN and DCP are photodegraded with this species faster than the parent compound phenol, very frequently employed as a model for aquatic contaminants, likely due to their lower pK(a) values. This observation allows the design of phenolic pesticides with different photodegradation rates under environmental conditions.     

基于物联网的智能家居控制系统设计

物联网是当前应用热点之一,已引起广泛关注。提出了基于物联网技术的智能家居控制系统实现方案,详细阐述了软硬件设计过程并给出了软硬件设计框图、原理图及部分软件代码。     

Factors of influence in the distribution of mold in the air in a wine cellar

This paper studies the presence of mold in the air of a vinification and ageing wine cellar. The influence of other factors such as the time of year, the sampling point, and the activity being carried out in the cellar has been analyzed. Neither the type of activity being carried out in the cellar nor the temperature or relative humidity fluctuations throughout the year are determining factors in the presence of mold in the air. For this group of microorganisms, the design of the cellar studied is the fundamental factor. Areas with little ventilation favor high levels of relative humidity and, hence, a higher presence of mold in the air. The mold population in these areas is not very diverse, which indicates that colonization by certain types of mold that have adapted to the conditions established therein is permanent. Areas with greater air flow, constant activity, and frequent cleaning show lower mold populations in the air and of a more varied composition. PRACTICAL APPLICATION: This work shows that given the growing importance of the presence of mold in wine cellars, the design thereof should take into account suitable ventilation of all the areas and control of the relative humidity. Hence, the presence of traditional underground areas for ageing wine, which is justifiable in seasons where temperature and humidity control lead to major technical problems, should be reconsidered in the design of new wine cellars.     

The association between acyl-CoA synthetase (ACSL4) polymorphism and intramuscular fat content in (Landrace × Yorkshire) × Duroc pigs

The aim of the study was to check whether different genotypes at acyl-CoA synthetase (ACSL4 locus, SNP G2645A) are associated with pork quality. 132 (Landrace × Yorkshire) × Duroc fatteners were genotyped by originally developed PCR-RFLP method. Upon the slaughter, the samples of longissimus lumborum muscle were taken from each carcass to determine the following parameters: content of water, protein and fat, pH (45 min, 24, 48, 96, and 144 h post mortem), electrical conductivity, drip loss, meat lightness, glycolytic potential, glycogen and lactate contents in meat. Among several associations observed, the highly significant (p<0.01) was found for intramuscular fat (IMF) content. Pigs with genotype GG revealed the highest content of IMF - 2.47%.     

Contrast inversion in electrostatic force microscopy imaging of trapped charges: tip-sample distance and dielectric constant dependence

We present a numerical and analytical study of the behavior of both electrostatic force and force gradient created by a charge trapped below the surface of a dielectric on an atomic force microscope tip as a function of the dielectric constant and tip-sample distance. As expected, the force decreases monotonously when the dielectric constant increases. However, a maximum in the dielectric constant dependence of the force gradient is found. This maximum occurs in the typical experimental parameters' range and depends on the tip-sample distance and the sample thickness. The analytical study permits us to understand the physical origin of this phenomenon and is in good agreement with the numerical simulation for small tip-sample distances. We also report a study exemplifying a possible contrast inversion in electrostatic force microscopy (EFM) signals while scanning, at different heights, two charges trapped in a sample having heterogeneous dielectric domains. In addition to this particular contrast inversion effect, this study can be considered as a way to gain insight into the mechanisms of EFM image formation as a function of the dielectric constant and tip-sample.     

Numerical study of the lateral resolution in electrostatic force microscopy for dielectric samples

We present a study of the lateral resolution in electrostatic force microscopy for dielectric samples in both force and gradient modes. Whereas previous studies have reported expressions for metallic surfaces having potential heterogeneities (Kelvin probe force microscopy), in this work we take into account the presence of a dielectric medium. We introduce a definition of the lateral resolution based on the force due to a test particle being either a point charge or a polarizable particle on the dielectric surface. The behaviour has been studied over a wide range of typical experimental parameters: tip-sample distance (1-20) nm, sample thickness (0-5) μm and dielectric constant (1-20), using the numerical simulation of the equivalent charge method. For potential heterogeneities on metallic surfaces expressions are in agreement with the bibliography. The lateral resolution of samples having a dielectric constant of more than 10 tends to metallic behaviour. We found a characteristic thickness of 100 nm, above which the lateral resolution measured on the dielectric surface is close to that of an infinite medium. As previously reported, the lateral resolution is better in the gradient mode than in the force mode. Finally, we showed that for the same experimental conditions, the lateral resolution is better for a polarizable particle than for a charge, i.e. dielectric heterogeneities should always look 'sharper' (better resolved) than inhomogeneous charge distributions. This fact should be taken into account when interpreting images of heterogeneous samples.