Porosity

孔隙度
  • 文章类型: Journal Article
    颗粒污染物,例如微塑料(1μm至5mm)和纳米塑料(<1μm),在许多陆地环境中传播。然而,目前尚不清楚粒子特性如何驱动其在土壤和含水层中的流动性,因为(i)所研究的模型粒子的环境相关性较差(例如,球形和单分散)和(ii)使用不允许直接观察沉积动力学的填充床实验。使用透明的二维多孔介质,这项研究分析了具有不规则形状和尺寸连续体(≈10nm至5μm)的粗糙聚苯乙烯碎片的沉积动力学。使用原位和非原位测量,在排斥条件下,随时间监测颗粒沉积随尺寸的变化。在没有天然有机物(NOM)的情况下,微米颗粒快速沉积并通过产生局部多孔粗糙度或障碍物促进较小纳米颗粒的物理拦截。在NOM的存在下,不再观察到根据粒径的差异,所有碎片都更容易被重新夹带,从而限制了存款的增长。这项工作证明了孔表面粗糙度和孔表面孔隙率对于胶体颗粒沉积的重要性,比如微塑料和纳米塑料,在排斥条件下。
    Particulate contaminants, such as microplastics (1 μm to 5 mm) and nanoplastics (<1 μm), are disseminated in many terrestrial environments. However, it is still unclear how particles\' properties drive their mobility through soils and aquifers due to (i) poor environmental relevance of the model particles that are studied (e.g., spherical and monodisperse) and (ii) the use of packed bed experiments which do not allow a direct observation of deposition dynamics. Using transparent 2D porous media, this study analyzes deposition dynamics of rough polystyrene fragments with irregular shapes and with a size continuum (≈10 nm to 5 μm). Using in situ and ex situ measurements, particle deposition as a function of size was monitored over time under repulsive conditions. In the absence of natural organic matter (NOM), micrometric particles rapidly deposit and promote the physical interception of smaller nanoparticles by creating local porous roughness or obstacles. In the presence of NOM, differences according to particle size were no longer observed, and all fragments were more prone to being re-entrained, thereby limiting the growth of deposits. This work demonstrates the importance of pore surface roughness and porosity of the pore surface for the deposition of colloidal particles, such as microplastics and nanoplastics, under repulsive conditions.
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  • 文章类型: Journal Article
    由于大都市与城市化相关的现象,建筑和拆除废物(CDW)的总量正在稳步增加。只有一小部分被回收生产新的混凝土,一种避免开采天然骨料的做法。此外,波特兰水泥生产过程导致高值的二氧化碳排放量释放到大气中,增加全球变暖的潜力。由于这些原因,替代普通波特兰水泥(OPC)的材料变得越来越普遍,如碱活化材料,which,当与再生骨料一起使用时,可以成为传统混凝土的环保替代品。在这项研究中,为含有再生混凝土骨料的碱活化偏高岭土砂浆制定了各种配合比设计。分析了它们在新鲜和硬化状态下的性能。遇到的主要问题是在再生混凝土骨料上存在粘附的砂浆层。该层不仅引起由开孔率增加引起的不利影响,而且还激活了竞争反应,从而部分损害了偏高岭土的碱活化。所有这些现象都恶化了含有再生骨料的复合材料的最终抗压强度。28天后,天然骨料替代量为12.5%的样品约为20MPa,替代量为25%的样品约为15MPa,与不更换的标准样品相比,相应减少了35%和50%,分别。
    The overall amount of construction and demolition waste (CDW) is steadily increasing due to urbanization-related phenomena in metropolitan cities. Only a small fraction is recycled to produce new concrete, a practice that would avoid the exploitation of natural aggregates. Furthermore, the Portland cement production process causes the release of high values of CO2 emissions into the atmosphere, increasing the global warming potential. For these reasons, materials alternative to ordinary Portland cement (OPC) are becoming more and more widespread, such as alkali-activated materials, which, when used with recycled aggregates, could become environmentally friendly substitutes for traditional concrete. During this study, various mix designs were formulated for alkali-activated metakaolin mortars containing recycled concrete aggregates. Their properties in the fresh and hardened states were analyzed. The main problem encountered was the presence of the adhered mortar layer on the recycled concrete aggregate. This layer not only caused a detrimental effect deriving from the increase in open porosity but also activated competitive reactions which partially compromised the alkali activation of metakaolin. All these phenomena deteriorated the final compressive strength of the composites containing recycled aggregates, which after 28 days, was around 20 MPa for samples with 12.5% of replacement of natural aggregate and 15 MPa for those with 25% of replacement, corresponding to a reduction of 35% and 50% compared to the standard sample without replacement, respectively.
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  • 文章类型: Journal Article
    对人牙本质孔隙率进行了多重分形表征。研究了从扫描电子显微镜(SEM)获得的人牙本质样品的显微照片,以表征孔隙率。我们得到了两种性别样本的灰度和二值图像上的孔隙空间和矩阵骨架的广义维数(多重分形矩)Dq$${D}_q$$。对于这个案子,我们发现,对于二进制图像,表面孔隙率ηs$$${\\\eta}_s$$与质量分形维数D0$${D}_0$$呈近似线性关系,即D0≈ηsd${D}_0\\大约{\\eta}_s\\\overline{d}$$。此外,孔径的概率密度分布(PDD)被发现是正常的PDD类型。其他感兴趣的数量,如平均,标准偏差,最大和最小孔径,voit比率,报告了化学成分的百分比。研究重点:SEM样品,详细介绍了多重分形分析的图像和过程。灰度中的微图案是多重分形的,而二元尺度中的微图案是单分形的。表面孔隙度与质量分形维数近似线性相关。从孔隙率值来看,voit比率确定。孔隙直径服从正常PDD。
    A multifractal characterization to human dentin porosity is made. Micrographs of human dentin samples gotten from scanning electron microscopy (SEM) were studied in order to characterize porosity. We got the generalized dimensions (multifractal moments) D q for pore space and matrix skeleton on gray scale and binary images for samples of both gender. For the case, we found that superficial porosity η s is linked to mass fractal dimension D 0 in an approximately linear relationship as D 0 ≈ η s + d ¯ for binary images. In addition, probability density distribution (PDD) for pore diameters is found a normal PDD type. Other quantities of interest like mean, standard deviation, maximum and minimum pore diameters, voit ratios, and percentage of chemical composition are reported. RESEARCH HIGHLIGHTS: SEM sample, images and procedure for multifractal analysis are detailed. Micro patterns in grayscale are multifractal and in binary scale are monofractals. Superficial porosity is relate to mass fractal dimension approximately linearly. From the porosity values, voit ratios are determined. Pores diameters obey a normal PDD.
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  • 文章类型: Journal Article
    我们继承下来的历史石遗产,一定要传给后人,不仅在我们发现它的相同条件下,如果可能,在更好的。建筑还需要更好,更耐用的材料,通常是石头。保护这些材料需要了解岩石的类型及其物理性质。这些性质的表征通常被标准化以确保方案的质量和再现性。这些必须得到旨在提高公司质量和竞争力以及保护环境的实体的批准。可以设想进行标准化的吸水率测试,以测试某些涂料在保护天然石材免受水渗透方面的有效性,但是我们发现这些协议的某些步骤忽略了石头的任何表面改性,因此,当亲水保护涂层(即,存在氧化石墨烯)。在这项工作中,我们分析了UNE13755/2008的吸水性标准,并提出了替代步骤,以适应涂层石材使用的规范。如果按原样应用标准协议,涂层石头的属性可能会使结果的解释无效,所以在这里我们特别注意涂层的特性,用于测试的水的类型,使用的材料,以及标本的内在异质性。
    The historical stone heritage that we inherit must be passed on to future generations, not only in the same conditions that we found it but, if possible, in better ones. Construction also demands better and more durable materials, often stone. The protection of these materials requires knowledge of the types of rocks and their physical properties. The characterization of these properties is often standardized to ensure the quality and reproducibility of the protocols. These must be approved by entities whose purpose is to improve the quality and competitiveness of companies and to protect the environment. Standardized water absorption tests could be envisaged to test the effectiveness of certain coatings in protecting natural stone against water penetration, but we found that some steps of these protocols neglect any surface modification of the stones, and hence may not be completely effective when a hydrophilic protective coating (i.e., graphene oxide) is present. In this work, we analyze the UNE 13755/2008 standard for water absorption and propose alternative steps to adapt the norm for use with coated stones. The properties of coated stones may invalidate the interpretation of the results if the standard protocol is applied as is, so here we pay special attention to the characteristics of the coating applied, the type of water used for the test, the materials used, and the intrinsic heterogeneity of the specimens.
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  • 文章类型: Case Reports
    模块化股骨杆头系统由于其易于应用和偏移调整而越来越多地使用。然而,这种模块化带来了耳轴磨损和断裂的复杂性。虽然很少遇到,耳轴骨折是一种灾难性的并发症,需要进行具有挑战性的翻修手术。本报告介绍了钴铬合金的耳轴断裂,全多孔涂层股骨柄。单阶段翻修手术后,在六周内实现了完全负重,患者用一根拐杖无痛地活动,在最后一次随访中髋关节评分为81分。尽管股骨柄和头部模型具有所有优点,人们应该记住,灾难性的并发症,如耳轴磨损和骨折,需要翻修手术是可能的。
    Modular femoral stem-head systems are used increasingly due to their ease of application and offset adjustment. However, this modular ity has brought complications of trunnion wear and breakage. Although very rarely encountered, trunnion fracture is a catastrophic com plication that requires challenging revision surgery. This report presents a trunnion fracture of a cobalt-chrome alloy, fully porous-coated femoral stem. Following single-stage revision surgery, full weight-bearing was achieved in six weeks, and the patient was painlessly mobile with a single cane and had a Hip Score of 81 in the last follow-up. Despite all the advantages of the femoral stem and head modu larity, one should remember that a catastrophic complication such as trunnion wear and fracture that require revision surgery is possible.
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  • 文章类型: Journal Article
    工业的扩大和人口的繁荣导致废水和下水道系统的安装增加,甚至靠近住宅区。这些装置的排放特别是挥发性有机硫化合物(VOSC),如甲硫醇(CH3SH),乙基硫醇(C2H5SH),二甲基硫化物(CH3SCH3)和二硫化碳(CS2)即使浓度很小,也会对人们造成伤害。用于去除的策略涉及添加化学品或通常昂贵的其它化学过程。生物过滤器,另一方面,消耗大量的能量和冲洗水。因此,要牢记商业化,重要的是制定一种策略,该策略具有成本效益,同时有效地去除这些系统中存在的大多数有气味的化合物。在目前的研究工作中,颗粒活性炭(GAC)用碱溶液进行功能化,以提高吸附能力。在当地污水处理厂的原污水帮助下,使用GAC和各种官能化活性炭(FACs)进行液相分批吸附。通过两种方法评估气味的浓度-用于感官测量的基于嗅觉测定法的分析和用于特定气味化合物的分析估计的基于GCMS的分析。官能化GAC的吸附能力较高,主要是因为在改性GAC的表面形成络合物。伪二级动力学模型与实验结果吻合良好,甲基和乙基硫醇在FAC-NH3上的吸附速率常数为0.0191mg/lmin和0.0153mg/lmin。Boyd的膜扩散以及速率动力学模型支持化学吸附形成限速步骤。响应面法(RSM)用于针对不同工艺参数(如吸附剂量和时间)优化VOSCs的去除。在BoxBehnken设计中采用6个因素,还优化了整体气味的嗅觉去除。分析结果的差异表明,所有模型都显示出相当大的拟合优度,R2值接近1。如从实验和优化研究中所证实的,甲硫醇被证明是总体气味的最高贡献者。优化的嗅觉去除气味(77.4%)以及CH3SH去除(80.34%),C2H5SH去除率(59.16%),在最佳工艺条件下,CH3SCH3去除率(63.21%)和CS2去除率(71.95%),吸附剂量为10.29g,吸附时间为2.92h。该结果表明,甲硫醇(CH3SH)是所研究的VOSCs中气味贡献最高的成分。结果表明,使用活性炭作为吸附剂从STP中去除有气味的化合物具有广阔的潜力。
    Expanding industries and booming population have led to the increase in the installation of wastewater and sewer systems, even in close proximity to residential areas. Emissions from these installations particularly volatile organo-sulphur compounds (VOSCs) such as methyl mercaptan (CH3SH), ethyl mercaptan (C2H5SH), dimethyl sulphide (CH3SCH3) and carbon disulphide (CS2) are a nuisance to people even when present in small concentration. Strategies for removal involve addition of chemicals or other chemical processes which are generally expensive. Biofilters, on the other hand, consume large amount of energy and wash waters. Hence keeping commercialization in mind, it is important to develop a strategy which would be cost-effective and at the same time be effective to remove most of the odorous compounds present in these systems. In the present research work, granular activated carbons (GAC) are functionalized with alkali solution to improve the adsorption capacity. Liquid phase batch adsorption is performed with GAC and various functionalized activated carbons (FACs) with the help of raw sewage water from a local sewage water treatment plant. Concentration of odour was evaluated by two methods-olfactometry-based analysis for sensory measurement and GCMS-based analysis for analytical estimation of a specific odorous compound. The adsorption capacities of the functionalized GACs are higher primarily because of complex formation at the surface of modified GACs. Pseudo-second-order kinetic model agreed well with experimental results with the rate constant being 0.0191 mg/l min and 0.0153 mg/l min for methyl and ethyl mercaptan adsorption onto FAC-NH3. Boyd\'s film diffusion along with rate kinetic model supported that chemical adsorption forms the rate-limiting step. Response surface methodology (RSM) was used to optimize the removal of VOSCs with respect to different process parameters like adsorbent amount and time. The olfactometry removal of overall odour was also optimized taking 6 factors in the Box Behnken design. Variance of analysis results indicated that all the models displayed considerable goodness of fit with R2 values close to 1. Methyl mercaptan turned out to be the highest contributor to the overall odour as confirmed both from experimental and optimization study. The optimized olfactometry odour removal (77.4%) along with CH3SH removal (80.34%), C2H5SH removal (59.16%), CH3SCH3 removal (63.21%) and CS2 removal (71.95%) was found at optimum process conditions, with amount of adsorbent of 10.29 g, adsorption time of 2.92 h. This result indicates that methyl mercaptan (CH3SH) is the highest odour contributing component out of the studied VOSCs. The results show promising potential for the use of activated carbon as an adsorbent for removal of odorous compounds from STPs.
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  • 文章类型: Journal Article
    地下水细菌污染一直是一个值得关注的生态问题。在这项研究中,分析了在宿主-病原体相互作用过程中具有不同鞭毛表型的肠沙门氏菌在多孔介质中的运输和沉积行为。在具有鞭毛运动性(野生型)或没有运动性(ΔmotAB)的不同菌株上进行了柱运输实验和改良的移动-固定模型,无鞭毛(ΔflgKL),甲基化和未甲基化鞭毛蛋白(ΔfliB),和不同的鞭毛阶段(FlyCON,fljBON)。结果表明,由于鞭毛具有移动和附着于表面的生物学优势,鞭毛运动可以促进细菌的运输和沉积。我们还发现,与ΔflgKL菌株相比,ΔmotAB菌株的保留率更高,因此非运动鞭毛的存在改善了细菌粘附。这表明细菌鞭毛和运动性都对沙质多孔介质中的细菌沉积具有促进作用。鞭毛相会影响细菌的运动;flagella菌株比fljBON菌株更快地通过色谱柱。此外,发现鞭毛甲基化有利于细菌的运输和沉积。总的来说,鞭毛修饰在环境条件下以不同方式影响肠道沙门氏菌的运输和沉积行为。
    Bacterial contamination of groundwater has always been an ecological problem worthy of attention. In this study, Salmonella enterica serovar Typhimurium with different flagellar phenotypes mainly characterized during host-pathogen interaction were analyzed for their transport and deposition behavior in porous media. Column transport experiments and a modified mobile-immobile model were applicated on different strains with flagellar motility (wild-type) or without motility (ΔmotAB), without flagella (ΔflgKL), methylated and unmethylated flagellin (ΔfliB), and different flagella phases (fliCON, fljBON). Results showed that flagella motility could promote bacterial transport and deposition due to their biological advantages of moving and attaching to surfaces. We also found that the presence of non-motile flagella improved bacterial adhesion according to a higher retention rate of the ΔmotAB strain compared to the ΔflgKL strain. This indicated that bacteria flagella and motility both had promoting effects on bacterial deposition in sandy porous media. Flagella phases influenced the bacterial movement; the fliCON strain went faster through the column than the fljBON strain. Moreover, flagella methylation was found to favor bacterial transport and deposition. Overall, flagellar modifications affect Salmonella enterica serovar Typhimurium transport and deposition behavior in different ways in environmental conditions.
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  • 文章类型: Journal Article
    在这里,我们展示了成功利用网状化学作为一种出色的设计策略,用于精心构建受奥林匹克五环启发的四羧酸锆金属有机框架(MOF)。HIAM-4017,具有前所未有的(4,8)-c底层网络拓扑,称为jcs,是通过对环的深刻重建和对非对称有机接头的明智设计而开发的。HIAM-4017具有高孔隙率和优异的化学和热稳定性。此外,激发态分子内质子转移(ESIPT)在等网状MOF中实现,HIAM-4018,由于将羟基引入接头骨架以诱导OH··N相互作用,因此斯托克斯位移为155nm。通过使用时间依赖性密度泛函理论(TD-DFT)彻底分析了此类相互作用。由于其良好的热稳定性和化学稳定性,和强烈的发光,制备了纳米尺寸的HIAM-4017和HIAM-4018并用于Cr2O72-检测。两种MOF都表现出优异的灵敏度和选择性。这项工作代表了在网状化学指导下构建特定于结构和属性的MOF的典范。
    Herein, we demonstrate the successful utilization of reticular chemistry as an excellent designing strategy for the deliberate construction of a zirconium-tetracarboxylate metal-organic framework (MOF) inspired by the Olympic rings. HIAM-4017, with an unprecedented (4,8)-c underlying net topology termed jcs, was developed via insightful reconstruction of the rings and judicious design of a nonsymmetric organic linker. HIAM-4017 exhibits high porosity and excellent chemical and thermal stability. Furthermore, excited-state intramolecular proton transfer (ESIPT) was achieved in an isoreticular MOF, HIAM-4018, with a large Stokes shift of 155 nm as a result of introducing the hydroxyl group to the linker skeleton to induce OH···N interactions. Such interactions were analyzed thoroughly by employing the time-dependent density functional theory (TD-DFT). Because of their good thermal and chemical stability, and strong luminescence, nanosized HIAM-4017 and HIAM-4018 were fabricated and used for Cr2O72- detection. Both MOFs demonstrate excellent sensitivity and selectivity. This work represents a neat example of building structure- and property-specific MOFs guided by reticular chemistry.
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  • 文章类型: Case Reports
    背景:初次全髋关节置换术(THA)手术次数的增加不可避免地导致翻修THA的要求增加。在髋臼严重破坏的患者中,常规植入物很难或不可能实现长期稳定性。
    目的:本病例报告提供了一种使用特殊的三维(3D)打印的多孔钛髋臼复合材料组件的成功治疗方法,该组件没有法兰处理PeproskII1B型髋臼缺损。
    方法:1例65岁女性患者,诊断为右髋关节假体松动伴巨大髋臼缺损。我们设计了骨盆的3D模型,并创建了个性化的3D打印多孔钛髋臼复合材料组件,用于翻修THA。手术是通过后外侧入路进行的,并将该部件植入缺损中,并使用钻孔导向器用杯形螺钉固定。
    结果:在2年的最后一次随访中,患者髋关节功能满意,未发现松动或其他并发症。
    结论:没有凸缘的3D打印多孔钛髋臼复合材料组件在治疗PeproskIII型髋臼缺损方面显示出有希望的临床和放射学结果。
    BACKGROUND: Increases in the numbers of surgical procedures for primary total hip arthroplasty (THA) inevitably lead to increases in the requirements for revision THA. The achievement of long-term stability is difficult or impossible by conventional implants in patients with severe destruction of the acetabulum.
    OBJECTIVE: This case report presents a successful treatment using a specific three-dimensional (3D)-printed porous titanium acetabular composite component without a flange in the management of Paprosky type IIIB acetabular defects.
    METHODS: A 65-year-old female diagnosed with right hip prosthetic loosening with a huge acetabular defect presented to our hospital. We designed the 3D model of the pelvis and created an individualized 3D-printed porous titanium acetabular composite component for revision THA. The procedure was performed through a posterolateral approach, and the component was implanted in the defect and fixed with cup screws using the drill guides.
    RESULTS: At the last follow-up at 2 years, the patient had a satisfactory hip joint function and no signs of loosening or other complications were found.
    CONCLUSIONS: The 3D-printed porous titanium acetabular composite component without a flange is showing promising clinical and radiological outcomes in the management of Paprosky type III acetabular defects.
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  • 文章类型: Case Reports
    多孔隔膜综合征包括所有胸膜腔疾病,包括胸腔积液,血胸,或者气胸,通过diaphragm膜缺陷继发于腹膜腔疾病。在这份报告中,我们描述了第一例已知的多孔膈肌综合征在腹腔镜子宫肌瘤切除术后表现为血胸。一名46岁的未产妇接受了腹腔镜下多发性肌瘤子宫肌瘤切除术。手术后八小时,患者出现劳力性呼吸困难,随后出现咯血。放射学诊断显示右胸腔有大量血胸。胸腔镜检查结果显示右膈中心有小窗,用胸腔镜修复。因此,快速的术后诊断导致成功的治疗。在这种情况下,多孔膈肌综合征被认为是由术中出血和腹腔内灌洗盐水滞留引起的,在腹腔里.多孔隔膜综合征是妇科外科医生在腹腔镜手术时代应该考虑的潜在威胁生命的疾病。
    Porous diaphragm syndrome includes all pleural cavity conditions, including pleural effusion, hemothorax, or pneumothorax, that occur secondary to peritoneal cavity disorders through defects in the diaphragm. In this report, we describe the first known case of porous diaphragm syndrome presenting as hemothorax after laparoscopic myomectomy. A 46-year-old nulliparous woman underwent laparoscopic myomectomy for multiple fibroids. Eight hours after surgery, the patient developed exertional dyspnea followed by hemoptysis. Radiological diagnosis revealed massive hemothorax in the right thoracic cavity. Thoracoscopic findings showed the presence of small fenestrae at the center of the right diaphragm, which were repaired thoracoscopically. Hence, quick postoperative diagnosis resulted in successful treatment. In this case, porous diaphragm syndrome is believed to be caused by retention of intraoperative bleed and saline from intra-abdominal lavage, in the abdominal cavity. Porous diaphragm syndrome is a potential life-threatening condition that gynecological surgeons should consider in this era of laparoscopic surgery.
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