Alkali Activated Cementitious Materials: An Overview

1991 ◽  
Vol 245 ◽  
Author(s):  
D. M. Roy ◽  
M. R. Silsbee
Keyword(s):  
Amorphous Materials ◽  
Cementitious Materials ◽  
Solution Chemistry ◽  
Reaction Products ◽  
Alumino Silicate ◽  
Alkali Activated ◽  
Very High

ABSTRACTAlkali-activated cementitious materials have considerable potential, with properties ranging from very high early strength to very high long term strength and low porosity. The role of alkalis in activating industrial by-products such as ground granulated (glassy) blast-furnace slag, ultra-fine silica fume or other by-product silicas, glassy fly ashes, and other amorphous materials is discussed. These by-product materials are activated by alkali additions which break the strong silicon oxygen bonds in the silicate or alumino-silicate network, accompanied by the formation of new reaction products. The role of the different components in multi-component activated cements on the reactivity and the nature of the resultant products is discussed. Characterization of starting materials and reaction products by XRD, SEM (including environmental SEM), chemical, and particle characterization techniques has been made. Additional results include investigation of pore solution chemistry as a function of time. Some inferences for long term durability are discussed.

VERITAS OBSERVATIONS OF RELATIVISTIC OUTFLOWS IN LOW- AND INTERMEDIATE-FREQUENCY-PEAKED BL LAC OBJECTS

2014 ◽  
Vol 28 ◽  
pp. 1460178
Author(s):  
◽  
HEIKE PROKOPH
Keyword(s):  
Gamma Ray ◽  
Intermediate Frequency ◽  
Bl Lac Objects ◽  
Bl Lacertae ◽  
Bl Lac ◽  
Bl Lacs ◽  
Gamma Ray Telescopes ◽  
Very High

The majority of blazars detected at very high energies (VHE; E > 100 GeV) are high-frequency-peaked BL Lac objects (HBLs). Low- and intermediate-frequency-peaked BL Lacs (LBLs/IBLs with synchrotron-peak frequencies in the infrared and optical regime) are generally more powerful, more luminous, and have a richer jet environment than HBLs. However, only a handful of these IBL and LBLs have been detected by ground-based gamma-ray telescopes, typically during high-flux states. The VERITAS array has been monitoring five known VHE LBLs/IBLs since 2009: 3C 66A, W Comae, PKS 1424+240, S5 0716+714 and BL Lacertae, with typical exposures of 5-10 hours per year. The results of these long-term observations are presented, including a bright, subhour-scale VHE flare of BL Lacertae in June 2011, the first low-state detections of 3C 66A and W Comae, and the detection and characterization of the IBL B2 1215+30.

scholarly journals Enzymatic treatment of long-term human marrow cultures reveals the preferential location of primitive hemopoietic progenitors in the adherent layer

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 291-297 ◽  
Author(s):  
L Coulombel ◽  
AC Eaves ◽  
CJ Eaves
Keyword(s):  
Stem Cells ◽  
Marrow Cell ◽  
Point Of View ◽  
Adherent Cell ◽  
Reproducible Method ◽  
Preferential Location ◽  
Very High ◽  
Marrow Cultures

Abstract Recent studies with long-term mouse marrow cultures have indicated the importance of the adherent layer as a primary reservoir of the most primitive stem cells, from which derivative stem cells and more differentiated progenitors are continuously generated. We have now examined the role of the adherent cell layer in long-term human marrow cultures from this point of view. Prerequisite to such an undertaking was the development of a nontoxic and reproducible method for detaching the adherent layer and making it into a single-cell suspension suitable for characterization by colony assays. Both trypsin and collagenase could be used to obtain suspensions that met these criteria. Lack of toxicity was demonstrated by the preservation of CFU-E, BFU-E, and CFU- C plating efficiency in fresh human marrow cell suspensions exposed to the same enzymatic treatments. Collagenase treatment of long-term marrow culture adherent layers was considered superior because it freed all hemopoietic colony-forming cells but left some of the other cells still adherent. Using this method, we found that CFU-C, BFU-E, and CFU- G/E were consistently detectable in the adherent layer for at least 8 wk, with the majority of the BFU-E and CFU-G/E being located in the adherent layer (70%-75% after 2–3 wk and more than 90% by 7–8 wk). Although corresponding numerical differences in adherent and nonadherent CFU-C populations were not observed, the colonies derived from them showed marked differences in the size they achieved; the adherent layer being the exclusive site of CFU-C, with a very high proliferative capacity. These findings emphasize the importance of assessing the progenitor content of the adherent layer of long-term human marrow cultures and provide an appropriate methodology.

Formation and characterization of the CuIn(S,Se)2/buffer layer interface in electrodeposited solar cells

2005 ◽  
Vol 865 ◽  
Author(s):  
N. Naghavi ◽  
C. Hubert ◽  
O. Roussel ◽  
L. Sapin ◽  
M. Lamirand ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Fill Factor ◽  
Open Circuit ◽  
Solution Chemistry ◽  
Complexing Agents ◽  
Complexing Agent ◽  
Main Role ◽  
Near Surface

AbstractThis paper presents the influence of the solution chemistry of chemical bath deposition (pH and complexing agents) on the performance of CuIn(S,Se)2 cells after an initial CN treatment. It is shown that it is possible to modify the deposition conditions of the CdS by increasing the pH of the solution and by replacing the complexing agent (ammonia) by citrate ions. Both NH3 based and citrate based process give very homogenous and covering thin films. However, in the case of the citrate based process a decrease of open circuit voltage (Voc) and fill factor (FF) and thus of the cell efficiencies is observed. This points out that the main role of the buffer layer is not only related to the specific properties of the CdS itself but also to the near surface modifications of the CuIn(S,Se)2 caused by the presence of the complexing agent in the bath.

Use of Ultrasound Biomicroscopy to Predict Long-Term Outcome of Sub-Tenon Needle Revision of Failed Trabeculectomy Blebs: A Pilot Study

2011 ◽  
Vol 21 (6) ◽  
pp. 700-707 ◽  
Author(s):  
Sushmita Kaushik ◽  
Anamika Tiwari ◽  
Surinder Singh Pandav ◽  
Parul Ichhpujani ◽  
Amod Gupta
Keyword(s):  
Ultrasound Biomicroscopy ◽  
Successful Outcome ◽  
Term Outcome ◽  
Long Term Outcome ◽  
Successful Group ◽  
Aqueous Flow ◽  
Needle Revision

Purpose. To evaluate the role of ultrasound biomicroscopy (UBM) in predicting the long-term outcome of sub-Tenon needling revision of failed trabeculectomy blebs. Methods. Adult patients with a failed trabeculectomy bleb and unsatisfactory intraocular pressure (IOP) control were recruited. The aqueous flow under the partial thickness scleral flap was looked for and the blebs classified on UBM as scleral route patent (SRP) or scleral route occluded (SRO). All blebs underwent needling revision with injection of 5 mg/0.1 mL 5-fluorouracil. Survival of the revision procedure at the end of 2 years follow-up with regards to the baseline UBM characterization of the bleb was noted. Successful outcome was defined as IOP <22.0 mmHg and/or 30% reduction of baseline IOP with or without medication. Results. A total of 13 eyes had SRP and 5 eyes had SRO blebs on UBM. Only SRP blebs survived the needling procedure by the end of 2 years. Of the 13 SRP blebs, 10 blebs survived (76.9%). Needling had failed in all 5 SRO blebs. The overall success rate was 55.6 % at 2 years. There was no difference in age, IOP, and time from initial trabeculectomy between the failed and successful group. The outcome correlated significantly to the patency of the scleral route assessed by UBM (p=0.07). Conclusions. Ultrasound biomicroscopy characterization of failed blebs appears to help in predicting the outcome of needle revision. In SRO blebs, it may be better to plan a full bleb revision rather than needling alone. Ultrasound biomicroscopy may help in avoiding an unnecessary needling procedure in SRO blebs where it is likely to fail.

scholarly journals The Corinth Rift Laboratory or an in situ Investigation on Interactions between Fluids and Active Faults

2007 ◽  
Vol SpecialIssue ◽  
pp. 35-38 ◽  
Author(s):  
F. H. Cornet
Keyword(s):  
Fluid Flow ◽  
Deformation Process ◽  
Active Faults ◽  
Localization Of Deformation

Earthquakes result from the sudden acceleration of a preliminary long-term slow deformation process. The objective of the Corinth Rift Laboratory (CRL) is to investigate <i>in situ</i> this quasistatic deformation process and mechanisms leading to a sudden catastrophic acceleration. Of particular interest is the characterization of the structure of the deforming zones and of the progressive localization of deformation. Special attention is given to the role of fluids but also on the influence of faults on regional fluid flow <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.s01.20.2007" target="_blank">10.2204/iodp.sd.s01.20.2007</a>

scholarly journals Alkali-activated materials: the role of molecular-scale research and lessons from the energy transition to combat climate change

2020 ◽  
Vol 4 ◽  
pp. 110-121 ◽  
Author(s):  
Claire White
Keyword(s):  
Portland Cement ◽  
Financial Incentives ◽  
Field Performance ◽  
Energy Transition ◽  
Combat Climate Change ◽  
Long Term Performance ◽  
Term Performance ◽  
Alkali Activated

Alternative (i.e., non-Portland) cements, such as alkali-activated materials, have gained significant interest from the scientific community due to their proven CO2 savings compared with Portland cement together with known short-term performance properties. However, the concrete industry remains dominated by Portland cement-based concrete. This Letter explores the technical and non-technical hurdles preventing implementation of an alternative cement, such as alkali-activated materials, in the concrete industry and discusses how these hurdles can be overcome. Specifically, it is shown that certain technical hurdles, such as a lack of understanding how certain additives affect setting of alkali-activated materials (and Portland cement) and the absence of long-term in-field performance data of these sustainable cements, can be mitigated via the use of key molecular- and nano-scale experimental techniques to elucidate dominant material characteristics, including those that control long-term performance. In the second part of this Letter the concrete industry is compared and contrasted with the electricity generation industry, and specifically the transition from one dominant technology (i.e., coal) to a diverse array of energy sources including renewables. It is concluded that financial incentives and public advocacy (akin to advocacy for renewables in the energy sector) would significantly enhance uptake of alternative cements in the concrete industry.

scholarly journals Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

2022 ◽  
Vol 8 ◽  
Author(s):  
Zhenguo Shi ◽  
Barbara Lothenbach
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Lithium Salts ◽  
Alkali Silica Reaction ◽  
Reaction Products ◽  
Ambient Conditions ◽  
Slow Kinetics ◽  
Zeolite Formation ◽  
Available Information

Effective mitigation of alkali-silica reaction (ASR) is critical for producing durable concrete. The use of alumina-rich supplementary cementitious materials (SCMs) and chemical admixtures such as lithium salts to prevent expansion caused by ASR was first reported 70 years ago, shortly after the discovery of ASR in 1940s. Despite numerous investigations, the understanding of the mechanisms of Al and Li for mitigating ASR remain partially inexplicit in the case of Al, and hardly understood in the case of Li. This paper reviews the available information on the effect of Al and Li on ASR expansion, the influencing factors, possible mechanisms and limitations. The role of Al in mitigating ASR is likely related to the reduction of dissolution rate of reactive silica. Moreover, the presence of Al may alter the structure of crystalline ASR products to zeolite or its precursor, but such effect seems to be not that significant at ambient conditions due to the slow kinetics of zeolite formation. Several mechanisms for the lithium salts in mitigating ASR have been proposed, but most of them are not conclusive primarily due to the lack of knowledge about the formed reaction products. Combination of Al-rich SCMs and lithium salts may be used as an economic solution for ASR mitigation, although systematic studies are necessary prior to the applications.

scholarly journals Extracellular Vesicles and Exosomes: Insights From Exercise Science

2021 ◽  
Vol 11 ◽  
Author(s):  
Joshua P. Nederveen ◽  
Geoffrey Warnier ◽  
Alessia Di Carlo ◽  
Mats I. Nilsson ◽  
Mark A. Tarnopolsky
Keyword(s):  
Extracellular Vesicles ◽  
Bioactive Molecules ◽  
Blood Collection ◽  
Exercise Science ◽  
Purification And Characterization ◽  
Exercise Response ◽  
Response To Exercise

The benefits of exercise on health and longevity are well-established, and evidence suggests that these effects are partially driven by a spectrum of bioactive molecules released into circulation during exercise (e.g., exercise factors or ‘exerkines’). Recently, extracellular vesicles (EVs), including microvesicles (MVs) and exosomes or exosome-like vesicles (ELVs), were shown to be secreted concomitantly with exerkines. These EVs have therefore been proposed to act as cargo carriers or ‘mediators’ of intercellular communication. Given these findings, there has been a rapidly growing interest in the role of EVs in the multi-systemic, adaptive response to exercise. This review aims to summarize our current understanding of the effects of exercise on MVs and ELVs, examine their role in the exercise response and long-term adaptations, and highlight the main methodological hurdles related to blood collection, purification, and characterization of ELVs.

Dose- and time-intensified ABVD without radiotherapy (RT) for advanced-stage Hodgkin lymphoma (HL) with mediastinal bulky disease (MBD).

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 8066-8066
Author(s):  
Gaetano Corazzelli ◽  
Filippo Russo ◽  
Ferdinando Frigeri ◽  
Francesco Volzone ◽  
Gaetana Capobianco ◽  
...  
Keyword(s):  
Event Free Survival ◽  
Cardiac Events ◽  
Bulky Disease ◽  
Free Survival ◽  
Nail Changes ◽  
Disease Free ◽  
Very High ◽  
Free Status

8066 Background: The role of consolidation RT on MBD after upfront chemotheraphy for advanced HL is debated, also given the supradditive iatrogenic risk. We present the results achieved in the subset of patients (pts) with MBD (max width > 1/3 of thoracic diameter) accrued in a phase II study of an intensified ABVD program without RT. Methods: The current analysis derives from the final evaluation of our trial for advanced HL (stage IIXB-IV) conducted from 06/2004 to 03/2010 (Russo et al, ASH 2009 abst 715). Pts were scheduled to 6 cycles of a ‘time-densified’ ABVD (3-week intercycle, drugs on days 1 and 11) with the first 4 cycles being also ‘dose-intensified’: doxorubicin (ADM) 35 mg/m2, days 1 and 11 and G-CSF on days 6-8 and 17-19. Results: Of 82 accrued pts, 39 had BMD at presentation. Median age was 29yrs (r 16-58); male 46%; stage IIB 48%, III 8%, IV 43%; B-sympt 87%, E-disease 53%; IP Score ≥3 51%. All pts completed the intensified program. Median actual dose intensities for ADM, bleomycin, vinblastine and dacarbazine were 23.12, 6.69, 3.96 and 245 mg/week, respectively; the increase over conventional ABVD was 85% for ADM and averaged 32% for the other agents. PET2 negativity was achieved in 36/39 (92%; 95% CI 79-98), complete responses (CR) in 37/39 [94%; 95% CI 82-99]. At a median f.u. of 54 mo.s (r 20-91) all pts are alive with an event-free survival of 89% (95% CI, 80-98). Events were: <CR (n=1, CS IVB), progression (n=1, CS IIIA), relapse [n=2; at 10 (CS IVA ) and 15 (CS IIB) months after treatment]; all these pts had isolated mediastinal recurrence. CTCAE v3.0 toxicity: Grade (G) 2 nail changes (31%), G2-G3 hemorrhoids (12%-3%), G3 infection (13%) and constipation (5%), G3-G4 stomatitis (7%-2%). No acute or delayed G3-G4 cardiac events, nor G3-G4 decline in pulmonary function (FEV1, DLCO,FEF25-75) were seen. Conclusions: Intensified ABVD can achieve PET2 negativity in a very high proportion of pts with MBD and ensure a long-term disease-free status even without RT. While results need confirmation on a randomized basis, the low mediastinal failure rate seems in line with recent suggestions that RT could be omitted in MBD when CR is achieved upon intensified chemotheraphy.

Sign in / Sign up

Export Citation Format

Share Document