Ultrasound based evaluation of hepatic steatosis and fibrosis in hepatitis C non-responders

Objective: To determine the accuracy of ultrasound in the diagnosis and grading of steatosis and fibrosis in Hepatitis C (HCV) patients not responding to ribavarin-interferon therapy.Study design: A cross-sectional, analytical study.Place and duration of study: Radiology Department, Civil Hospital, Karachi, from March 2008 to August 2010.Methodology: Patients with positive HCV RNA despite 24 weeks ribavarin-interferon therapy (non-responders) were subjected to ultrasound and biopsy prior to institution of pegylated interferon therapy for detection and grading of steatosis and fibrosis. Using histopathology as the gold standard, sensitivity, specificity, negative and positive predictive values for ultrasound were determined.Results: The sensitivity of ultrasound for hepatic steatosis was 90.9% for no steatosis (NS), 100% for moderate and gross steatosis and 84.4% for mild steatosis with 100% specificity. The sensitivity for fibrosis was 25% for no fibrosis, 100% for mild fibrosis, 89.74% for moderate fibrosis and 100% for gross fibrosis. The overall accuracy for detection of steatosis was 95.39% and that for fibrosis was 98.02%. Hepatic vein showed increased dampening of flow with advancing grades of steatosis and fibrosis.Conclusion: Ultrasound has a high accuracy in the diagnosis and grading of steatosis and fibrosis in HCV nonresponders. Mild fibrosis may confound the diagnosis of mild steatosis

Finite element modelling of fully encapsulated cable bolts in laboratory large scale pull out test

Modelling cable bolts in numerical software is a challenging task. Cables are made from multiple strands wound together and when loaded, they tend to act in a way more complex manner than rock bolts. This study used laboratory data from large scale pull out testing of fully encapsulated cable bolts using cementitious grout. A finite element method was adopted and a series of engineering simplifications and assumptions were made to increase the efficiency of the model. The results were able to illustrate a better capability in modelling the bulbed cables compared to the plain cables. Also, the sensitivity analysis proposed that increasing cable diameter for a given hole size (decreasing grout annulus thickness) can increase the overall peak load value, similar to an increase in concrete confinement, grout uniaxial compressive strength, and bulb size

Static and dynamic tendon pull-out test research at the University of Wollongong

Tendon technology is widely used for strata control in underground coal mines, in both primary and secondary support systems. The understanding of how they work is crucial to effective strata reinforcement design. Research on tendon technology is an evolving study and this paper is aiming at maintaining this evolution by continuing research on load transfer mechanisms under both static and dynamic conditions, which was reported initially by (Anzanpour, 2021) in ROC2021. This programme of study includes testing of different strength capacity cable bolts, which have been important in the stabilisation of the ground around mining excavations affected by rock bursts and ground seismicity. The aim of the study was to evaluate tendon performance in different loading environments. From a series of tests carried out in the most recent study, it was found that in pull testing, the load transfer characteristics vary with respect to the type of testing. The required dynamic energy for pulling-out a cable bolt can be between 50-80% lower than the static load, based on the cable type and its geometry (Plain or Bulbed). Debonding and pullout mechanisms regardless of loading rate, seem to be similar in both static and dynamic tests, however, plain cable bolts behave differently from bulbed cable bolts in reaction to pull-out load

Determination of potting media for effective acclimatization in micropropagated plants of tea clone Iran 100

Establishment of in vitro plantlets in the greenhouse on various additives of soil mixtures is considered as one of the trickiest phases of micropropagation. In the present research, we report the results of experiments aimed at optimizing acclimatization of tea clone Iran 100 plantlets (Camellia sinensis (L.) O. Kuntze) by using different types and ratios of potting media. Potting media like peat moss, vermiculite and perlite having various ratios are mixed together. This experiment was done in four repetitions by keeping the base of randomized complete block design. The properties such as survival rate, number of leaves, plant height and root length were measured and recorded in the period of the experiment. The collected data was analyzed by SAS statistical software and the mean of data was evaluated by the Tuckey Test using the probability of 1 percent. Nevertheless, the mixture containing peatmoss+ vermiculite+ perlite (2:1:1; v/v/v) resulted in increased percentage of plant survival, root length plant height and number of leaves of tea clone Iran 100 and it is therefore, a recommended medium for growth of the cultivar during acclimatization

Stabilization of Tropical Peat by Chemical Grout.

Peats have low shear strength and high deformation characteristics. Cement, sometimes with other industrial binders, is widely used for the stabilization of peats by deep mixing. However, peats lack a favorable structure for the chemical reactions, coupled with high moisture content that is acidic in nature. So, the efficiency of the binders is low making it an expensive option. This paper presents the effectiveness of using calcium chloride and kaolinite in cement-sodium silicate grout for improving the strength of tropical peat. The change in shear strength of the treated samples was evaluated by the vane shear test and moisture content test. The microstructural changes were evaluated by scanning electron microscopy and energy dispersive x-ray spectrometer analysis. Calcium chloride seemed to have different effects on the shear strength of peat and was observed to play an important role in the effectiveness of the chemical stabilizers. Experimental results showed that kaolinite (more than 10%) has a crucial rule in increasing the shear strength of peat. It was observed that sodium silicate within 3% and cement has favorable effect on the shear strength of peat and induce a decrease in the moisture content of mixtures consisting of peat and themselves and also lead to some favorable changes in the microstructure

Effect of aggressive pH media on peat treated by cement and sodium silicate grout

The effects of aggressive peat nature (pH) on the strength of peat treated by cement and cement-sodium silicate grout were investigated by evaluating the changes in unconfined compressive strength, moisture content, and scanning electron microscopy (SEM) of samples with time in different pH media. The results indicate that peats treated by cement-silicate have higher strength than peats treated by cement, due to an increase in pH value of the media. Furthermore, cement and cement-silicate are highly effective in reducing the moisture content and void ratio of the treated peats. The microstructures of treated peats support the laboratory test results

Comprehensive sensitivity analysis on static and dynamic reservoir parameters impacting near wellbore injectivity during CO2 sequestration

Carbon capture and storage (CCS) is proved to be effective measure for reducing CO2 emissions. whilst the world still highly depends on the use of fossil fuel energy, this method is necessary for reaching the world’s 1.5 °C goal. In CCS, CO2 is hindered from entering the atmosphere by capturing it from sources of emission and storing it in geological formation. Saline aquifers among all possible underground formations are most common targeted ones for CO2 storage due to their frequent presence, and large storage capacity. However, this storage option suffers from sufficient well injectivity to inject large volumes of CO2 at acceptable rates through a minimum number of wells. The injectivity impairment / reinforcement happens through mineral dissolution, fine particle movement, salt precipitation and hydrate formation (known so far). Each of these mechanisms will be more dominant in injectivity alteration at different distance from the injection point depending on reservoir pressure and temperature, formation water salinity, rock mineralogy, and flow rate of CO2 injection as well as its dryness. Incorporating all the finding into radial flow near wellbore will help gaining insight into the resultant of injectivity changes over time and distant from injection point. In this study we have chosen Eclipse 300 together with an open-source code to investigate the impact of formation characteristics, CO2 -Brine-Rock interaction, pressure, temperature as well as injection rate on injectivity alteration. The goal for this work is to provide a workflow which can help predicting injectivity alteration using the existing tools. Simulation results show that the high homogenous horizontal permeability in combination with vertical flow baffles in the formation (among all other parameters) has positive impact on storage capacity by increasing residual trapping. However, permeability is affected severely by salt precipitation during CO2 injection. Combined static and dynamic parameter study demonstrate that the injection rate plays a crucial role in size and expansion of CO2 plume as well as growth rate of dry out zone length, amount of salt precipitation and length of equilibrium region. The higher the injection rate, the quicker activation of the capillary and gravity force which leads to drag more brine to near well-bore resulting in higher volume fraction of salt precipitation. However, low injection rate could result in smaller CO2 plume, shorter dry out zone and longer equilibrium region in term of distance from injection point

Application of numerical modeling in study of the behaviour of cable bolts under axial loading

Over the past few decades, the rapid development of efficient mathematical algorithms and the increasing availability of powerful computers have made it possible to develop realistic constitutive models. With the development of highly sophisticated constitutive models, the Finite Element Method (FEM) has become an invaluable tool for predicting ultimate loads and the associated failure mechanisms. Consequently, more capable and realistic models can be developed to analyze and design various types of structures. This paper concentrates on the application of FEM model for better understanding of the behaviour of cable bolts under axial loading conditions. A detailed geometry of the pullout practice has been generated based on the previous laboratory pullout experiments. The interaction between the cable bolt and encapsulation material has been observed and compared with the experiments. Once the models were verified, the failure mechanism of the encapsulation material has been analysed. Results indicated that numerical models can assist to expand the knowledge on the different pullout scenarios while saving time and energy and producing less environmental waste from laboratory tests; however, primary verification of the models are essential

Aspects of testing tendon supports for strength, effective installation, and performance in different ground formation

Different methods and techniques are reported in testing several types of tendons including solid rebars and cable bolts to evaluate their strength and performances in various rock formations. Most reported studies are laboratory-based, enhanced occasionally with numerical studies. Moreover, some tests are also carried out in situ to verify test results obtained from laboratory studies. The laboratory strength studies involved both push and pull testing, single and double shear testing of solid rebar, fiberglass rods, and cable bolts using different grout types installed in composite mediums of varied strength. Several challenges are faced when undertaking these various tests. These challenges may contribute to inconsistencies in the test results caused by various parameters, which are recognized, and the findings of these studies are examined and reported. This paper highlights a range of factors that influence tendon system performance based solely on two decades of tendon research by the rock mechanics group of the School of Civil, Mining, Environmental and Architectural Engineering, the University of Wollongong to draw the attention of the researcher on the importance of these factors and their influence in the real installation environment