Pengaruh Penambahan Expander terhadap Nilai Susut Beton

Salah satu sifat beton adalah susut, dimana susut terjadi karena perubahan volume beton saat mengalami proses pengerasan akibat adanya proses penguapan air bebas pada muka beton saat proses hidrasi berlangsung. Penggunaan bahan tambah yang dapat mengembang (expander) dapat menimbulkan reaksi yang membuat bertambahnya volume beton yang mampu menghambat laju susut beton. Pennelitian ini dilakukan dengan menambahkan expander pada campuran beton dengan variasi penambahan 0, 0.45, 0.60, dan 0.90% dari jumlah semen untuk mengetahui pengaruh terhadap kuat tekan dan nilai susut beton pada arah horizontal. Campuran beton yang dipakai merupakan campuran beton dengan mutu beton rencana 20 MPa. Benda uji yang digunakan untuk uji susut merupan beton berbentuk balok 10 x 10 x 28,5 cm. Benda uji kuat tekan menggunakan sampel berbentuk silinder dengan diameter 15 cm dan tinggi 30 cm. Pengujian susut beton mengacu kepada ACI 209R-92 dengan durasi pembacaan selama 90 hari. Dari hasil penelitian didapat hasil bahwa beton mengalami susut yang signifikan pada 14 hari pertama. Penambahan expander 0.45% dari berat semen mampu menurunkan susut sebesar 14%. Penambahan expander 0.60% dari berat semen mampu menurunkan susut sebesar 16%. Penambahan expander 0.90% dari berat semen mampu menurunkan susut sebesar 56%. Penambahan expander terhadap beton dengan mutu 20 MPa mampu menaikkan kuat tekan beton. Penambahan expander 0.45% dari berat semen mampu menaikkan kuat tekan beton sebesar 0,25%. Penambahan expander 0.60% dari berat semen mampu menaikkan kuat tekan beton sebesar 0,5%. Penambahan expander 0.90% dari berat semen mampu menaikkan kuat tekan beton sebesar 0,8%

Evidence for the Role of B Cells and Immunoglobulins in the Pathogenesis of Multiple Sclerosis

The pathogenesis of multiple sclerosis (MS) remains elusive. Recent reports advocate greater involvement of B cells and immunoglobulins in the initiation and propagation of MS lesions at different stages of their ontogeny. The key role of B cells and immunoglobulins in pathogenesis was initially identified by studies in which patients whose fulminant attacks of demyelination did not respond to steroids experienced remarkable functional improvement following plasma exchange. The positive response to Rituximab in Phase II clinical trials of relapsing-remitting MS confirms the role of B cells. The critical question is how B cells contribute to MS. In this paper, we discuss both the deleterious and the beneficial roles of B cells and immunoglobulins in MS lesions. We provide alternative hypotheses to explain both damaging and protective antibody responses

Hydrologic Conditions Describe West Nile Virus Risk in Colorado

We examine the relationship between hydrologic variability and the incidence of human disease associated with West Nile virus (WNV; family Flaviviridae, genus Flavivirus) infection (hereafter termed “human WN cases”) in Colorado from 2002 to 2007. We find that local hydrologic conditions, as simulated by the Mosaic hydrology model, are associated with differences in human WN cases. In Colorado’s eastern plains, wetter spring conditions and drier summer conditions predict human WN cases. In Colorado’s western mountains, drier spring and summer conditions weakly predict human WN cases. These findings support two working hypotheses: (1) wet spring conditions increase the abundance of Culex tarsalis vectors in the plains, and (2) dry summer conditions, and respondent irrigational practices during such droughts, favor Cx. pipiens and Cx. tarsalis abundance throughout Colorado. Both of these processes potentially increase the local vector-to-host ratio, favoring WNV amplification among competent avian hosts and bridging to humans

Plasma exchange and glucocorticoid dosing in the treatment of anti-neutrophil cytoplasm antibody associated vasculitis (PEXIVAS): protocol for a randomized controlled trial.

BACKGROUND: Granulomatosis with polyangiitis (GPA, Wegener's) and microscopic polyangiitis (MPA) are small vessel vasculitides collectively referred to as anti-neutrophil cytoplasm antibody-associated vasculitis (AAV). AAV is associated with high rates of morbidity and mortality due to uncontrolled disease and treatment toxicity. Small randomized trials suggest adjunctive plasma exchange may improve disease control, while observational evidence suggests that current oral glucocorticoid doses are associated with severe infections in patients with AAV. A randomized study of both plasma exchange and glucocorticoids is required to evaluate plasma exchange and oral glucocorticoid dosing in patients with AAV. METHODS/DESIGN: PEXIVAS is a two-by-two factorial randomized trial evaluating adjunctive plasma exchange and two oral glucocorticoid regimens in severe AAV. Five hundred patients are being randomized at centers across Europe, North America, Asia, and Australasia to receive plasma exchange or no plasma exchange, and to receive standard or reduced oral glucocorticoid dosing. All patients receive immunosuppression with either cyclophosphamide or rituximab. The primary outcome is the time to the composite of all-cause mortality and end-stage renal disease.PEXIVAS is funded by the National Institute of Health Research (UK), the Food and Drug Administration (USA), the National Institutes of Health (USA), the Canadian Institute of Health Research (Canada), the National Health and Medical Research Council (Australia), and Assistance Publique (France). Additional in-kind supplies for plasma exchange are provided by industry partners (TerumoBCT, Gambro Australia, and Fresenius Australia). DISCUSSION: This is the largest trial in AAV undertaken to date. PEXIVAS will inform the future standard of care for patients with severe AAV. The cooperation between investigators, funding agencies, and industry provides a model for conducting studies in rare diseases. TRIAL REGISTRATION: Current Controlled Trials: (ISRCTN07757494) and clinicaltrials.gov: (NCT00987389).RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are