Technical note: forage in vitro dry matter digestibility as influenced by fiber source in the donor cow diet

Objectives of this study were to determine the influence of five donor cow diets that differed in source of fiber on true in vitro DM digestibility of eight forages. Test forages included two alfalfa (31.2 and 38.3% NDF), corn silage (50.2% NDF), oat forage (48.2% NDF), perennial rye (62.1% NDF), two reed canarygrasses (55.9 and 68.1% NDF), and timothy (68.2% NDF). Sources of fiber in donor cow diets were alfalfa haylage or alfalfa haylage plus either corn cobs, cottonseed hulls, oat hulls, or soy hulls. In addition, the effect of filtering through sintered glass crucibles or filter paper (two replicates each) was evaluated. There were differences (P < .01) among feeds in in vitro DM digestibility, but there were no interactions (P > .05) between test forages and either source of fiber in donor diets or filtration method. There was an interaction between source of fiber in the donor diet and method of filtration (P < .01). Samples inoculated with ruminal fluid from cows fed diets with oat hulls or soy hulls had lower (P < .01) in vitro DM digestibility when filtered on crucibles than on filter paper. Filtration method did not affect (P > .05) in vitro DM digestibility of samples inoculated with ruminal fluid from other diets. The in vitro DM digestibility of samples inoculated with ruminal fluid from cows fed alfalfa haylage was less than the in vitro DM digestibility when other inocula were used. The source of fiber in the donor cow diet and filtration method can affect in vitro DM digestibility, but relative ranking of forages was unaffected by these variables.     

Maintenance of low screen filtration pressure in blood stored in a new liquid medium: BAGPM

Formation of microaggregates in blood stored in conventional media is reflected by rapidly rising screen filtration pressure (SFP). We show that the BAGPM (bicarbonate, adenine, glucose, phosphate, and mannitol) blood preservation system maintains SFP at near normal levels throughout the storage period of 42 days. Whenever the SFP had a tendency to rise in BAGPM blood, filtration through a routine in-line blood filter reverted SFP back to baseline levels. Blood from the same donors stored in citrate-phosphate-dextrose (CPD) adenine had a rapidly rising SFP by 7 to 14 days of storage. Filtration through the routine blood filter had no effect on the SFP of blood stored in CPD-adenine, CPD, or ACD. BAGPM not only maintains adequate levels of ATP and 2,3-diphosphoglyceric acid (2,3-DPG) during full 42 days of storage but also offers a unique system in which microparticulate material is prevented from forming, with maintenance of low SFP, perhaps because of its low leukocyte, platelet, and fibrinogen content.     

提高立式叶滤机设备整体效率的实践

拜耳法工艺生产氧化铝过程中,从分离沉降槽溢流的粗液中往往残留着微量的浮游物,如果不清除这些浮游物,那么在分解工序中这些浮游物作为氢氧化铝的晶核而进入产品氧化铝中,影响产品质量。铝酸钠溶液的粗液精制控制过滤设备一般采用凯利卧式叶滤机、高效立式叶滤机及一部分传统的袋滤机,各种过滤设备在精液精制系统中表现出了不同的应用技术特点。本文全面分析了立式叶滤机的运行机理特点和效益,利用OEE工具对立式叶滤机影响因素进行分析,并提出改进措施,改进后设备的OEE提高315.49%。     

Fatigue in HIV illness: relationship to depression, physical limitations, and disability

Several filters specific for respiratory function tests have been on the market for several years. Recommended by the manufacturers to avoid contaminating the equipment and thus improve patient safety, these filters require a considerable financial investment. We studied the passage of diluted blood into artificial saliva in a patient model simulating inspiration tests and rapid forced expiration to assess the retention capacity of three filters used for respiratory function tests: Multi SPIRO MI-90016 (MultiSPIRO), PF 30S (Pall Biomedical) and Spirobac (Dar. S.p.A). The mean percentage of passage was 1.48% through the MI-90016 filter, 57.15% through the PF 30 S filter and 70.45% through the Spirobac filter. These findings provide further elements for choosing filters for respiratory function tests. Indeed, despite the manufacturers' commercial arguments, the technical documents provided do not give necessary information on the filtering capacity of the filters on the market. We have observed that two out of the three filters tested do no meet the standards expected by clinicians.     

精矿过滤技术研究现状

过滤在选矿工艺中起着至关重要的作用,有效降低精矿含水量已成为选矿领域一项重要研究课题。系统介绍了过滤设备在精矿脱水中的应用,详细阐述了真空过滤设备和压滤机的结构特点、发展及研究现状,重点指出了影响精矿过滤的主要因素,并针对增强精矿过滤的性能提出了相应措施。     

Removing oxide and sulfide inclusions from molten steel by filtration

On the basis of thermodynamic calculations indicating that rare-earth sulfide inclusions may form in molten nonalloyed structural steel, the influence of filtration on the content of sulfur, oxygen, and nonmetallic inclusions in the steel is investigated. It is found that filtration removes the oxide phase and oxygen from 30Л steel. There is no change in the content of sulfide inclusions and sulfur. Filtration of steel preliminarily treated with 0.05–0.30% rare-earth metals removes 10–60% of the sulfur. Metallographic data show that the content of both oxide and sulfide inclusions is reduced here. Gray impressions of filter templates show that the sulfur-bearing phase is removed by an adhesive mechanism: this phase adheres to the filter surface, forming continuous borders around it.     

Diagnosing ascitic etiology on a biochemical basis

BACKGROUND/AIMS: The analysis of ascitic fluid has been complicated by several new tests. To simplify its assessment, we evaluated ascitic fluid pH with six other parameters prospectively and simultaneously in blood and ascitic fluid in sixty patients with ascites. METHODOLOGY: Sixty patients were selected on whom abdominal paracentesis was performed in order to determine which tests were the most reliable for the etiological diagnosis of ascites. Their ascitic fluid pH, cholesterol, albumin, and total proteins were analyzed to distinguish between malignant and cirrhotic ascites. The diagnosis of cirrhosis was based on histological findings, and/or clinical, biochemical, and endoscopic/ultrasonographic findings in whom percutaneous liver biopsy was contraindicated. RESULTS: The serum-ascites albumin gradient was higher (p<0.001) in cirrhotic as compared to tubercular, malignant or cardiac ascites. We discovered that ascitic fluid lactate dehydrogenase and cholesterol were best for diagnosing malignant ascites, ascitic fluid glucose and ascitic fluid/blood glucose ratio were perfect for diagnosing tubercular ascites, and ascitic fluid pH and lactate dehydrogenase were suitable for diagnosing spontaneous bacterial peritonitis. Correspondingly, ascitic fluid albumin, ascitic fluid/serum albumin, total proteins, and serum ascites albumin gradient were best for diagnosing sterile cirrhotic ascites. CONCLUSIONS: Diagnostic paracentesis is a useful procedure. The practice of ordering a battery of tests on every ascitic fluid specimen should be abandoned. Rather, an algorithm approach should be adopted in which the results of initial analysis guide us to further relent tests that help in arriving at the etiology of ascites.     

Clinical and experimental studies of intraoperative autotransfusion using a new filtration device

The Haemocell S-350 device has recently been introduced for intraoperative autotransfusion. The system uses a novel membrane filter to process shed blood. In the first part of this study a 0.2-micron pore size filter was used in a randomized trial comparing the use of autotransfusion (n = 8) with bank blood controls (n = 9) during aortic reconstruction. This part of the trial was abandoned because of unexpected non-surgical bleeding. Bank blood requirements fell from a median of 3.0 (range 0.0-9.0) units to 1.5 (range 0.0-7.0) units when autotransfusion was used, but these patients had a greater perioperative blood loss (1791 (range 932-3104) versus 1140 (range 440-3840) ml). There was evidence of postoperative heparin excess with an activated partial thromboplastin time ratio of 1.3 (range 0.9-3.0) versus 1.0 (range 1.0-1.2) in controls and an activated clotting time of 206 (range 143-280) versus 137 (range 107-142) s. This was confirmed by raised plasma heparin levels and a prolonged thrombin time normalized by protamine. To improve performance a 0.6-micron pore size filter was studied in ten patients. Filtration efficiency doubled from 19 to 38 per cent. Electron micrographs demonstrated better filter clearance, but 44 per cent of the original concentration of heparin remained in the reinfusate. The S-350 device may be an attractive alternative to centrifugation for intraoperative autotransfusion but, until efficiency is improved, it should only be used for cardiovascular surgery when excess heparin can be reversed with protamine.     

Analysis of liquid flow through ceramic porous media used for molten metal filtration

A two-dimensional mathematical model has been developed to study fluid flow inside ceramic foam filters, used for molten metal filtration, as a function of their structural characteristics. The model is based on the selection of a unit cell, geometric model, formed by two interconnected half-pores. The good agreement between experimental and computed permeabilities showed that the unit cell model approximates very well the effect of filter structure on the flow conditions inside the filter. The validity of the model is supported by the fact that permeabilities are calculated from directly measured structural parameters,i.e., without the introduction of any fitting variable, such as tortuosity. The laminar flow solutions for the Navier-Stokes equation, in steady state, were obtained numerically using the control-volume method. The boundary of the unit cell was represented through axisymmetrical, body-fitted coordinates to obtain a better representation of the complex pore shape. The generality of the model, to study fluid flow in reticulated media, was tested by comparing the computed specific permeabilities with values measured for ceramic foam filters and for the new ceramic filter of lost packed bed (CEFILPB). Such a comparison shows good agreement and discloses a fundamental property of the last kind of porous medium: the critical porosity. The model indicates how porosity and pore dimensions of reticulated filters may be tailored to meet specific fluid flow requirements.     

Study of inclusion re-entrainment in a filter bed

Filtration is widely used in various processes such as water treatment and aluminum casting for the removal of unwanted impurities called inclusions. The deposited inclusions can re-enter the flow as a result of the unfavorable hydrodynamic conditions within the system or flow instabilities, such as flow stop/start periods during casting cycles in the aluminum industry. In this project, the re-entrainment of inclusions was studied as a function of filter-bed length, particle size, inlet inclusion concentration, and inlet velocity. A physical model using water containing PVC particles as inclusions was built. Experiments were carried out under continuous-flow as well as interrupted-flow conditions in this pilot-scale filter. It was found that the smaller bed particles and longer bed length enhance the deposition and reduce the re-entrainment of inclusions. Increasing the inlet velocity has a negative effect on the deposition and increases the re-entrainment. A one-dimensional mathematical filtration model has also been developed, and its predictions were compared with the experimental data from the pilot filter and the plant. This article presents the experimental study, its results, and the comparison between model predictions and experimental data. Applicability of the model to aluminum filtration is also illustrated.     

Removal of Inclusions from Aluminum Through Filtration

Filtration experiments were carried out using both an AlF₃ slurry-coated and an uncoated Al₂O₃ ceramic foam filter to study the removal of nonmetallic inclusions and impurity elements. The results showed that the 30-ppi ceramic foam filter removed up to 85 pct inclusions from aluminum. Several pictures of two- and three-dimensional morphologies of both nonmetallic and intermetallics inclusions also have been presented. The following contributing mechanisms for the removal of nonmetallic inclusions in the deep-bed filtration mode are proposed: (1) collision with walls and interception effect and (2) the formation of both intermetallic and nonmetallic inclusion bridges during filtration. Fluid dynamics modeling of inclusion attachment to the filter walls showed that most inclusions, especially those with larger sizes, are entrapped at the upper part of the filter, whereas smaller inclusions are dispersed well throughout the filter. The calculated inclusions removal fractions for the 30-ppi filter showed that almost all inclusions >125 μm are removed, and inclusions ~5 μm in size are removed up to 85 pct. The interfacial energy between two collided same-size inclusions was calculated, indicating that a strong clustering of inclusions may result within the filter window. Magnesium impurities were removed up to 86 pct by the AlF₃ slurry-coated filter. The filter acted in active filtration mode in addition to the contribution of the air oxidation of dissolved [Mg], which was calculated to be 13 pct. The total mass transfer coefficient of dissolved [Mg] to the reaction interface was calculated to be 1.15 × 10⁻⁶ m/s.     

Karl Terzaghi: From Theory to Practice in Geotechnical Filter Design

In a period of just over 10 years, Karl Terzaghi proved the idea of a weighted filter in simple laboratory tests while on faculty at the American Robert College in Turkey, patented the concept, developed empirical rules for the grain size distribution of filter through specialist consulting advice on relatively small weirs in Europe, and firmly established those rules as a basis for engineering practice on the Bou-Hanifia Dam in North Africa. The Terzaghi filter criteria are commonly attributed to experience gained on that latter project. However, an evaluation of unpublished letter reports, contract documents, and correspondence suggests the evolution of those criteria for soil retention and permeability occurred during his earlier collaboration with the Austrian consulting company of J. Pfletschinger & Co. This new insight appears to be confirmed by the uncovering of a draft patent claim, prepared in the name of Josef Pfletschinger, which sets out the precise details of those filter criteria and whose existence was acknowledged in contract documents for Bou-Hanifia.     

覆膜滤料的滤尘性能测试方法研究

由于覆膜滤料的结构和性能有别于普通滤料，因而普通滤料的滤尘性能测试方法不完全适用于覆滤料。本文作者在总结实践经验的基础上，提出了在覆膜滤料的滤尘性能测试中应注意的一些问题和应增加的测试项目。     

A Model of Foam Filters

Filtration with foam filters is reported as a successful method to remove inclusions from top-cut silicon scrap. Inclusions in top-cut silicon scrap are needle-like Si₃N₄ particles and round SiC inclusions. A high filtration efficiency of more than 99 pct for 30-ppi SiC filters is achieved. The inclusions that remain are mainly SiC particles smaller than 10 μm. Possibly these particles are primarily secondary inclusions. The filtration efficiency increases with decreasing filter pore size. The main factor that plays a role in deep-bed filtration seems to be interception. Various models are considered to estimate the removal efficiency of foam filters by this mechanism. Here, we propose a new model called “the branch” model. This model gives a high filtration efficiency and agrees the best with the experimental results.     

Investigation on fouling mechanisms for recombinant human growth hormone sterile filtration

During sterile filtration of recombinant human growth hormone solutions, severe membrane fouling was experienced compared to other protein preparations of significantly higher molecular weights and concentrations. This phenomenon was attributed to rhGH aggregation/adsorption occurring in the filter pore. To better understand this phenomenon, we examined several possible fouling mechanisms: (1) pore constriction, (2) adsorption due to nonspecific binding between protein and the membrane, (3) shear-induced adsorption, (4) hydrophobic interface-induced aggregation/adsorption. The protein solutions were sterily filtered using 0.22 mm filters, and their filtration fluxes were monitored. Filtration on the capillary and the noncapillary filters suggested that constraints by pore constriction and tortuosity played only a limited role. Filtration using filters with different degrees of protein binding tendency suggested that nonspecific adsorption was insignificant. The shear stress acting on the protein during filtration was small. RhGH which was intentionally sheared in a high-speed concentrically rotating device did not aggravate fouling tendency, suggesting that the shear-induced adsorption might not be the major fouling mechanism. The dynamic light scattering data showed a trace amount of rhGH aggregates always present in equilibrium with the hydrophobic (air-water and membrane-water) interface. These aggregates tended to be adsorbed to the membrane, and more aggregates were generated presumably due to the equilibrium between aggregates and protein monomers. This adsorption/aggregation process eventually fouled the membrane. When the hydrophobic interface was occupied by surfactant molecules, the equilibration kinetics ceased to generate aggregates, thereby minimizing membrane fouling. This study clarified the cause of such an unusual fouling phenomenon upon microfiltration.     

Quantitative analysis of the intrinsic muscles of the foot

In the Homopteran order of insects, the plant xylem feeders exhibit a highly differentiated part of their digestive tract known as the filter chamber. In this tissue, water crosses plasma membranes through a transepithelial osmotic gradient. In previous studies on the filter chamber of Cicadella viridis, we purified and characterized from the plasma membranes a 25 kDa protein that we demonstrated to be an aquaporin (or water channel, member of the major intrinsic protein family, a group of membrane channels for small solutes). We called this protein AQPcic for Cicadella aquaporin. In the present study, we used polyclonal antibody anti-AQPcic in Western blotting and immunocytochemical analysis of the intestinal tract of Cercopis sanguinolenta, Philaenus spumarius, Aphrophora alni (Cercopidae), Euscelidius variegatus, and Scaphoideus titanus (Jassidae). Western blotting experiments revealed that immunologically related AQPcic proteins are found in those species. The molecular weight of these proteins is 15-26 kDa. Immunocytochemical studies on ultrathin filter-chamber sections revealed that the anti-AQPcic antibody systematically labelled the membrane microvilli of epithelial cells. A good correlation thus exists between the physiology of these cells and the presence of aquaporin-related proteins in their membranes.     

铜钼混合精矿分离浮选工业试验研究

介绍了国外从斑岩铜矿中回收钼的主要矿山和进行铜、钼浮选分离的主要方法。乌努格吐山大型斑岩铜钼矿选矿通过小型试验和前期工业试验,找出了工业生产中存在铜钼混合精矿脱水脱药不理想、陶瓷过滤机无法过滤-325目含量占88%铜精矿的问题。最后经过尝试,用原有陶瓷过滤机过滤混合精矿,脱水脱药效果明显,并使用加压过滤机过滤铜精矿,解决了陶瓷过滤机无法过滤细粒级铜精矿的难题。选矿工艺流程经改造后,试生产连续产出了合格的钼精矿,钼精矿品位为48%、含铜1.2%。同时,对铜、钼分离工艺中的一些主要问题进行了分析讨论。     

Immunofixation electrophoretic techniques applied to identification of proteins in serum and cerebrospinal fluid

We describe the application of immunofixation staining of agarose-gel electrophoretograms in areas where its use in the clinical laboratory is appropriate. Immunofixation electrophoresis consists of an electrophoretic phase followed by a fixation phase in which antiserum is used to precipitate the protein. As long as the antibody is in slight excess or near equivalency, the antigen/antibody complex remains insoluble. The reaction can be detected by visual inspection in indirect light, by protein staining, or by use of antibodies labeled with fluorescein, enzyme, or isotope. In the method described here we primarily have used protein staining (Coomassie Blue) to accentuate the proteins fixed by antisera. All unreacted proteins are removed by pressing with filter paper and saline washing. In the clinical laboratory, this method expedites immunochemical evaluation of samples and may also supplement immunoelectrophoresis. It has been applied successfully in identifying small obscure monoclonal proteins in the serum and cerebrospinal fluid of patients with multiple sclerosis, subacute sclerosing panencephalitis, biclonal gammopathies, serum monoclonal light chains, and mobility shifts of certain proteins, particularly of the complement series. Immunofixation demonstrates that the protein bands present in spinal fluid from multiple sclerosis and subacute sclerosing panencephalitis patients are of the IgG class of immunoglobulins; and non-IgG protein, such as beta and gamma trace proteins, are not detected. We also comment on reverse immunofixation with labeled antigen as a branch of the procedure that allows detection of function of the immunoglobulins separated by electrophoresis.     

Stress Deformation and Fluid Pressure of Bone Specimens under Cyclic Loading

Cyclic loading has been known to induce fluid flow and thus mechanotransduction in bones. In the past, four-point bending tests have been used exclusively in studying fluid flow in bones. In order to better understand the mechanism of deformation and fluid flow under loading, compression tests were done on trabecular bone specimens under drained and undrained conditions. In the drained tests, the volume change was observed, whereas in the undrained tests, excess pore fluid pressure was measured. Cyclic loading tests were conducted in addition to monotonic loading tests to observe the permanent volume change or excess pore fluid pressure with loading cycles. A fast loading rate gave a sharp rise in the excess fluid pressure compared to a slow loading rate. The strength and stiffness of the specimens appeared to deteriorate with an increased speed of loadings, but there was no appreciable difference between the results obtained from drained and undrained tests. The drained and undrained tests as described allowed a better understanding of bone behavior under loadings for a coupled stress-flow analysis.     

基于离散裂缝模型的页岩油储层压裂渗吸数值模拟

对于含黏土矿物较高的页岩油储层,地层水的矿化度可高达4.786×103 mol·m?3,压裂过程中与注入的低矿化度压裂液形成的渗透压作用显著。为探究渗透压对渗吸的影响作用,建立了综合考虑渗透压和毛管力渗吸作用的油水两相二维离散裂缝网络模型,开展了页岩油储层压裂液泵注和关井阶段渗透压、毛管力、关井时间、盐浓度、膜效率、分支缝面积占比等对渗吸的影响规律研究。结果表明:①滤失主要由压力差、毛管力和渗透压3种机制驱动,其中压力差是滤失的关键控制机制;②关井时间对压裂液的渗吸作用影响较大,关井50 d时,前15 d渗吸量可达到总渗吸量的80%,且关井压力扩散会波及到两侧压裂段;③与压力扩散相比,渗透压达到平衡的时间较长,对于地层水矿化度为4.786×103 mol·m?3的情况,裂缝附近的矿化度达到600 mol·m?3左右所需关井时间为50 d;④由于压力差是渗吸主要驱动力,页岩膜效率对渗透压力扩散影响微弱,页岩膜效率30%与5%相比渗吸量仅增加4%;⑤对于密切割压裂,关井后,含水饱和度受小间距水力裂缝控制,分支缝对渗吸含水饱和度的影响有限。