Influence of Silica Fume, Fly Ash, Super Pozz, and High Slag Cement on Water Permeability and Strength of Concrete

In this study, effects of mineral admixtures on the water permeability and compressive strength of concretes containing silica fume (SF) and fly ash (FA), super pozz (SP) were experimentally investigated. Permeability of concrete was determined through DIN 1048 (Part 5). The research variables included cement type, ordinary Portland cement (OPC) or high slag cement (HSC), and mineral admixtures content were used as a partial cement replacement. They were incorporated into concrete at the levels of 5%, 10%, and15% for silica fume and 10%, 20%, 30% for fly ash, or super pozz by weight of cement. Water- cement ratio of 0.40 was used and tests were carried out at 28 days. From the tests, the lowest measured water permeability was for the 10% super pozz and 10% silica fume or 20% fly ash mixes. Although the highest compressive strengths of concretes determined was 10% silica fume mix for ordinary Portland cement and were reduced as the increase in the replacement ratios for other mineral admixtures than ordinary Portland cement concrete.The main objective of this research was to study the water permeability and compressive strength of concrete containing silica fume, fly ash, and super pozz and high slag cement to achieve the best concrete mixture have lowest permeability. The results were compared to the control concrete ordinary Portland cement concrete without admixtures. The optimum cement replacement by FA, SP and SF in this experiment is 10% SP. The knowledge on the strength and permeability of concrete containing silica fume and fly ash, super pozz and high slag cement could be beneficial on the utilization of these waste materials in concrete work, especially on the topic of durability

The role of rheology in modelling elastic waves with gas bubbles in granular fluid-saturated media

Elastic waves in fluid-saturated granular media depend on the rheology which includes elements representing the fluid and, if necessary, gas bubbles. We investigated the effect of different rheological schemes, including and excluding the bubbles, on the linear Frenkel–Biot waves of P1 type. For the wave with the bubbles the scheme consists of three segments representing the solid continuum, fluid continuum, and a bubble surrounded by the fluid. We derived the Nikolaevskiy-type equations describing the velocity of the solid matrix in the moving reference system. The equations are linearized to yield the decay rate lambda as a function of the wave number k. We compared the lambda(k)-dependence for the cases with and without the bubbles, using typical values of the input mechanical parameters. For the both cases, the lambda(k)-curve lies entirely below zero, which is in line with the notion of the elastic wave being an essentially passive system. We found that the increase of the radius of the bubbles leads to faster decay, while the increase in the number of the bubbles leads to slower decay of the elastic wave

Numerical assessment of the overall heat transfer and pressure drop performances of an aqueous ammonia base-nanofluids in rectangular microchannel heat sinks

In this paper, the thermal and hydrodynamic performances of an aqueous ammonia base-nanofluid (Al2O3-NH3(aqu)) cooled in a rectangular microchannel heat sink was numerically investigated. The range of Reynolds number used in the investigation were between 140-1400. In order to assess the performance of the system during the employment of the proposed nanofluid, H2O and Al2O3-H2O were also tested and their performances were compared to Al2O3-NH3(aqu) performance in terms of thermal resistance and pressure drop. Results from the simulation showed that the proposed nanofluid outperformed pure water and slightly higher than Al2O3-H2O in terms of thermal resistance (for Re = 1400, 0.0474, 0.0449 and 0.04647 oK/W for H2O, Al2O3-H2O and Al2O3-NH3(aqu), respectively). However, it exceeds the performance of both pure water and Al2O3-H2O in terms of pressure drop (for Re = 1400, 785288, 911217, 753591 Pa for H2O, Al2O3-H2O and Al2O3-NH3(aqu), respectively). The key findings from the current study may be used to attract more research about the proposed nanofluid to be used in the cooling process of microchannel heat sinks

Bioactive Lactoferrin-Derived Peptides

Lactoferrin (LF) is a member of the transferrin family that is a cationic iron-binding protein. It is an 80-kDa glycoprotein that is found in many secretions in the body and is highly present in milk and colostrums. It exerts antibacterial effects and has a wide range of biological activities. Moreover, it is considered as a precursor of different peptides that have multifunctional bioactivities. During the last decade, several applications of LF and its peptides have been discovered, which has led to its commercial production. Therefore, LF and its peptides can offer a variety of specialized ingredients that can be tailored to meet the needs of natural food preservatives and functional food ingredients

Pengaruh PH, Kecepatan Putar dan Asam Asetat terhadap Karakteristik CO2 Corrosion Baja ASME SA516 Grade 70

Fenomena korosi merupakan sesuatu yang pasti terjadi pada setiap logam. Laju korosi dari suatu material dipengaruhi oleh beberapa faktor diantaranya yaitu nilai pH lingkungan dan karakteristik aliran fluida yang kontak langsung dengan logam. Pada oil and gas industry, baja ASME SA 516 grade 70 sering digunakan sebagai material flowline dan banyak terjadi CO2 Corrosion. Penelitian ini bertujuan untuk melakukan studi laju korosi material baja ASME SA 516 grade 70 yang mengandung CO2. Penelitian dilakukan dengan metoda weight loss menggunakan alat Rotating Cylinder Electrode (RCE) selama 10 hari dan metode Polarization selama 1 jam. Selain itu digunakan pula XRD dan SEM guna mendukung data-data analisa. Pada penelitian ini digunakan media elektrolit NaCl 3,5% dengan kandungan CH3COOH sebesar 0 ppm dan 1500 ppm dengan variasi kecepatan putaran yaitu 0 RPM, 150 RPM, 300 RPM, dan 450 RPM pada pH 5 dan 6. Pada pengujian polarization, didapatkan hasil laju korosi tertinggi sebesar 9.9323 mm/y pada larutan CH3COOH 1500 ppm pH 5 dan kecepatan putar 450 RPM, sedangkan data dari pengujian weight loss sebesar 4.8795 mm/y. Hasil pengamatan SEM menunjukkan adanya perbedaan morfologi pada permukaan spesimen karena pengaruh kecepatan putaran. Kecepatan putaran mengakibatkan tergerusnya produk korosi oleh aliran. Pada pengujian XRD dengan menggunakan spesimen pH 5 dengan kandungan 0 ppm dan 1500 ppm 0 RPM ditemukan FeCO3, Fe(OH)3 dan senyawa FeOOH sebagai produk korosi

Effects of sublattice symmetry and frustration on ionic transport in garnet solid electrolytes

We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at non-integer Li concentrations, while ordered phases explain regions of sharply lower conductivity. Disorder is therefore predicted to be optimal for ionic transport in this and other conductor families with strong Li interaction.Comment: 6 pages, 4 figures, and supplementary informatio

Laparoscopic Thal versus laparoscopic Nissen fundoplication in children: Comparative study regarding outcome and patient satisfaction

Introduction Gastroesophageal reflux disease is a common condition in pediatric age group. Many surgeons believe that complete fundoplication provides better reflux control, yet it results in more dysphagia and gas-bloat symptoms. On the other hand, a partial wrap is reported to have fewer adverse effects but a higher failure rate in controlling reflux. Until now, there is no agreement and little evidence as to whether complete or partial  fundoplication is the optimal procedure in this age group.Patients and methods This is a prospective singleblinded randomized comparative study that included 30 patients who were admitted in the time period from May 2013 to May 2015 and were treated laparoscopically byeither Nissen or Thal fundoplication.Results Operative time (minutes) was significantly longer in the Thal group (186 ± 52) when compared with the Nissen group (150 ±48) (P =0.031). Intraoperative complications showed no significant difference when comparing the two groups. Although the incidence of postoperative dysphagia was statistically insignificant, the duration of dysphagia did  show significantly shorter duration in the Thal group (median: 6 days), when compared with the Nissen group (median: 17 days). There was no recurrence in the Thal group, whereas there was one recurrence in the Nissen group.Conclusion This study suggests that Thal fundoplication offers an effective alternative to Nissen fundoplication with apparently shorter duration of dysphagia and thus earlier return to the normal eating pattern. Level of evidence