The relationship between textural properties of selected Nigeria rocks and penetration rate of top-hole hammer drill was investigated. These rock samples were tested in the laboratory for mineral composition, silica content and porosity. Also, average grain size and packing density were determined from photomicrograph of the samples using empirical equations proposed by researchers. Penetration...

Achieving minimum cost and time in reservoir drilling requires evaluating the effects of the drilling parameters on the penetration rate and constructing a drilling rate estimator model. Several drilling rate models have been presented using the drilling parameters. Among these, the Bourgoyne and Young (BY) model is widely utilized in order to estimate the penetration rate. This model relates s...

Limited efficacy of chemotherapeutic drugs against solid tumors has been attributed to poor drug penetration into tumor tissues. Multicellular layer (MCL) cultures recapitulate barriers to drug penetration and distribution and have been used successfully in the production of clinically relevant data. In the present study, we evaluated the characteristics of paclitaxel (PTX) and 5-fluorouracil (...

The Oxford Unicompartmental Knee replacement (UKR) was introduced as a design to reduce polyethylene wear. There has been one previous retrieval study involving this implant, which reported very low rates of wear in some specimens but abnormal patterns of wear in others. There has been no further investigation of these abnormal patterns. The bearings were retrieved from 47 patients who had rece...

Trifluorothymidine (F3TdR) and idoxuridine (IDU) were observed to penetrate through the cornea from the epithelial side at a greater rate than adenine arabinoside (ARA-A) during in vitro corneal perfusions. Removal of the epithelium increased the rate of penetration of F3TdR and IDU by about twofold and the rate of ARA-A penetration by fivefold. The kinetics of antiviral penetration did not dis...

pits, quarries, and on construction sites. The prediction of the penetration rate of drilling machines is very important for cost estimation and planning of rock excavation projects. Many researchers have investigated percussive drilling theoretically or experimentally and correlated the penetration rate with various rock properties. Protodyakonov (1962) developed drop tests and described the c...

This paper presents a modified form of the Walker-Anderson (W-A) model for analyzing high velocity penetration of an eroding projectile into a concrete target in which the W-A model is improved by incorporating calculations for the plastic flow field of concrete in terms of its compressibility and strain rate sensitivity under severe pressure. With the changes to and calculations of plastic fie...

This paper analyzes the factors affecting China’s mobile commerce diffusion at the infant stage and taking-off stage using the data of 31 provinces of China in the years of 2009 and 2012 respectively based on the partial least square regression method. The results of the analysis indicate that fixed broadband penetration rate, GDP per capita and internet penetration rate, urbanization level are...