STRATEGIES TO IMPROVE SHRINKAGE RESISTANCE OF CEMENT-BASED MATERIALS FOR EXTRUSION-BASED 3D PRINTING

The main objective of this study is to develop new generation of shrinkage-resistant 3D printable mortar mixtures. To this end, the research work was carried out to: i) identify key material and processing parameters that affect printability; ii) investigate the influence of water-to-cement ratio, superplasticizer dosage, and welan gum content on mortar printability; iii) propose a “printability window” where rheological properties and desorptivity can secure successful printing; iv) investigate effect of shrinkage mitigation materials (expansive agent (EA), pre-saturated lightweight sand (LWS), superabsorbent polymers (SAP), and shrinkage reducing admixture) on printability and shrinkage performance of mortar; and v) evaluate the effect of EA, LWS, steel and synthetic fibers on chloride-induced corrosion and transport properties of concrete. The research work indicated that: i) in addition to rheology and printing parameters, desorptivity (the rate of fluid filtration during extrusion) can also present a significant influence on printability; ii) for extrusion speed of 2.5 mm/s, extruder capacity of 135 N, and nozzle size of 9 mm, the printability window encompasses yield stress of 100-470 Pa, plastic viscosity of 10-60 Pa.s, and desorptivity values \u3c 3x10 -3 s-0.5; iii) the use of welan gum can enable development of print materials that are most suitable for 3D printing. The addition of welan gum (up to 0.6%) significantly reduced the desorptivity, which enabled extrusion of print material with yield stress \u3e 400 Pa and contributed to lower mass loss due to plastic shrinkage; and iv) the use of SAP is effective at reducing desorptivity and such polymers with slower absorption and desorption kinetics are more effective to ensure shape stability and efficient internal curing of print materials --Abstract, p. i

Industrial Pollution: Contamination of Surface Water & Human Health in Veerapura, Bangalore

Articlehttp://deepblue.lib.umich.edu/bitstream/2027.42/96998/1/UMURJ-Issue07_2010-MVallurupalli.pd

Rabbit or Tortoise? Rethinking Customer Acquisition at Dravya Bank

A prominent bank in India has swiftly and consistently lost market share for a high-revenue product. It has diagnosed poor communication with customers as the underlying cause. As such, it has begun to contemplate whether to direct its resources towards analytics and digital advertising channels or to continue to improve its current advertising techniques that revolve around mass marketing initiatives and its large network of branches. The case expects participants to evaluate the costs and benefits of alternatives available to the bank and propose a comprehensive customer-acquisition strategy to address the crisis. We write the case in the form of a roleplay, which participants in class can enact to boost their interest and involvement in it

Temporal Changes in the Impact of Drivers of Online Review Influence

Traditional IT introduction approaches tend to follow a goal-driven, top-down logic, whereby management evaluates and selects technology that is then imposed on end-users. In this research-in-progress paper, it is argued that such approaches are not appropriate for enterprise social software (ESS) as a type of malleable technology requiring end-user appropriation. Through an embedded researcher relationship with a case organisation, a research approach and preliminary findings are presented in which the juxtaposition of two, client and consultant, practices align with either a top-down or employee-centric view regarding ESS. By utilizing a practice breakdown lens, this paper explores the tensions that are revealed in ESS projects as the two practices struggle to socially construct a joint solution for ESS inside client organisations. This unique context affords studying the particular nature of ESS and solutions for its uptake, as breakdowns foreground the role of the end-user in malleable technologies

Fabrication and Characterization of Schottky diode and Heterojunction Solar cells based on Copper Phthalocyanine (CuPc), Buckminster Fullerene (C60) and Titanium Dioxide (TiO2)

Organic solar cells are cheaper and much easier to fabricate than the conventional inorganic solar cells, but they suffer from low efficiencies due to low carrier mobilities in organic films. In this study Copper Phthalocyanine (CuPc) and Buckminster Fullerene (C60) based Schottky diodes were fabricated on ITO coated glass substrates to study their performance and a study of the effect of thickness on the cell parameters of CuPc Schottky diodes was made. Also, TiO2 based devices were studied to see the effect of TiO2 layer on the cell parameters. The J-V curves were analyzed for series resistance, diode ideality factor and reverse saturation current density. The devices were also characterized by SEM and XRD measurements

Formwork pressure and rheology of self consolidating concrete

The objective of this work was to understand the mechanisms responsible for formwork pressure drop over time in case of self consolidating concrete (SCC). The fresh state properties of SCC, mortar, and cement paste mixes like workability, static yield stress gain and temperature change over time were evaluated and correlated with the formwork pressure data. The mix parameters for the concrete, mortar mixes like water to cementitious ratio, the addition of fly ash, aggregate content, maximum aggregate size, aggregate moisture content, addition viscosity modifying agent, the addition of fibers were investigated. Emphasis was also placed on studying the influence of formwork dimensions on the formwork pressure. The results showed that the formwork pressure drop over time was highly dependent on the thixotropy which can be measured from static yield stress and dynamic yield stress gain over time. So a method for achieving the accurate yield stress values using the ICAR rheometer was developed. The accuracy of the pressure data obtained using the pressure sensors was also evaluated. Based on the results obtained, the accuracy of the Lange and Tejeda model in predicting the formwork pressure of self consolidating concrete was studied. The results showed that within first few hours of the pressure decay, the reversible changes in concrete dominate the pressure decay and slight variation in the mix proportions, mixing procedure alter the pressure decay significantly indicating the sensitivity of SCC mixes. The formwork dimensions also affect the pressure decay indicating the importance of including the formwork dimension parameter while developing the models for prediction of formwork pressure. Recommendations were made for reducing the variation in the mix properties, the importance of focussing on the particle to particle interaction within concrete for understanding its thixotropic properties that seem to be the primary cause of the pressure decay in the initial hours after casting before the hydration process becomes dominant

Atrioventricular Dissociation after Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is increasingly used as a treatment for psychiatric disorders. Cardiac effects are the principal cause of medical complications in these patients. We report a case of atrioventricular (AV) dissociation that occurred after ECT that was treated with pacemaker implantation. The mechanisms contributing to the onset of AV dissociation in this patient, and the management and rationale for device therapy, in light of the most recent guidelines, are reviewed

Identifying Targetable Liabilities in Ewing Sarcoma

Background: Despite multi-modality therapy, the majority of patients with metastatic or recurrent Ewing sarcoma (ES), the second most common pediatric bone malignancy, will die of their disease. ES tumors express aberrantly activated ETS transcription factors through translocations that fuse the EWS gene to ETS family genes FLI1 or ERG. The aberrant activation of ETS transcription factors promotes malignant transformation and proliferation. While, FLI1 or ERG cannot be readily targeted, there is an opportunity to deploy functional genomics screens, to develop novel therapeutic approaches by identifying targetable liabilities in EWS/FLI1 dependent tumors. Materials and Methods: We performed a near whole-genome pooled shRNA screen in a panel of five EWS/FLI1 dependent Ewing sarcoma cell lines and one EWS/ERG cell line to identify essential genes. Essential genes were defined as those genes whose loss resulted in reduced viability selectively in ES cells compared to non-Ewing cancer cell lines. Essential hits were subsequently validated with genomic knockdown and chemical inhibition in vitro, followed by validation of the on-target effect of chemical inhibition. Next, we determined the in vivo effects of small-molecule inhibition on survival and tumor growth in NOD scid gamma (NSG) mice with established subcutaneous ES xenografts. Results: Top hits in our screen that could be readily targeted by small-molecule inhibitors, and thus have potential for rapid clinical validation, were selected for further investigation. These hits included IKBKE, CCND1 and CDK4. IKBKΕ, a non-canonical IKK with an oncogenic role in breast cancer, was one of the top kinase hits in the screen. IKBKΕ shares significant homology to TBK1, another non-canonical IKK that is essential in k-RAS dependent lung cancer. We validated IKBKE through small-molecule inhibition of IKBKE/TBK1 and shRNA based knockdown. Ewing sarcoma cell lines are sensitive to low micromolar concentrations of two IKBKE/TBK1 inhibitors (CYT387 and MRT67307). Additionally, in a panel of ES cell lines, knockdown of IKBKE resulted in decreased growth and impaired colony formation. These observations, paired with impairment of NF-κB nuclear localization following CYT387 treatment suggests that non-canonical IKK mediated signaling may be essential in Ewing sarcoma. We further validated these results through inhibition of IKBKE/TBK1 in in vivo xenograft models treated with 100 mg/kg/day of CYT387. Treatment over the course of twenty-nine days resulted in a significant increase in survival (p-value = 0.0231) and a significant decrease (p-value = 0.036) in tumor size after fifteen days of treatment. CDK4 and CCND1 are highly expressed in Ewing sarcoma as compared to other tumor types. shRNA mediated knockdown of CDK4 and CCND1 resulted in impaired viability and anchorage independent growth. Furthermore, treatment of Ewing sarcoma cell lines with a highly selective CDK4/6 inhibitor, LEE011, resulted in decreased viability (IC50 range of 0.26-18.06 μM), potent G1 arrest in six of eight EWS/FLI1 containing Ewing sarcoma lines tested and apoptosis in a panel of four highly sensitive lines. Administration of 75 mg/kg/day and 250 mg/kg/day of LEE011 in NSG mice with Ewing xenografts resulted in significant impairment of tumor growth, (p-value <0.001 for both treatment arms), as compared to vehicle control. Conclusions: These studies suggest a role for the targeting of IKBKE and CDK 4/6 in Ewing sarcoma, findings with immediate clinical relevance for patients with this malignancy, because small-molecule inhibitors of these proteins have already entered clinical trial for other disease indications