Alkali-activated foam: Understanding the relationship between rheology, activator-precursor interaction, and pore characteristics

The pore characteristics and stability of alkali-activated foams (AAFs) are crucial factors that determine their application and performance. These aspects are influenced by the material mix design and the foaming method employed. The interaction between the activator and precursor paste results in a change in the rheological properties which possess significant impacts on the behaviour of the foam and the stability of the pores in AAFs. Various raw materials and foaming methods have been utilised to develop AAFs. However, The combined influence of the activator-precursor interaction, foaming, and rheological properties on the pore structure and properties of AAFs is not well explored. Hence, the purpose of this study is to investigate this interrelationship. To develop AAFs, a combined mechanical and chemical foaming method was employed. Waste glass, fly ash, and slag were used as precursors and activated using activators with varying silica modulus. The rheological parameters of the paste and the hardened properties of the AAFs were investigated. The findings indicate that pastes with high viscosity and high yield stress have more stable and uniformly distributed pores. The presence of a viscous activator reduces the colloidal interaction between precursor particles, thereby lowering the yield stress of the activated paste. Furthermore, the early setting of slag and the partial dissolution of all precursors play a significant role in establishing stable networks and final pore stabilisation within the AAFs. Controlling these parameters, lightweight AAFs were developed using a high volume of waste glass with homogeneous pore distribution and moderate mechanical strength (up to 2.83 MPa)

Massive malignant pleural effusion due to lung adenocarcinoma in 13-year-old boy

A 13-year-old boy with no risk factors for lung cancer presented with a massive left-sided pleural effusion and a mediastinal shift on chest radiography and computed tomography. A chest tube drained bloody pleural fluid with an exudative pattern. A pleural biopsy and wedge biopsy of the left lower lobe revealed mucinous adenocarcinoma in the left lower lobe wedge biopsy and metastatic adenocarcinoma in the pleural biopsy. The patient is currently undergoing chemotherapy. Radiotherapy is planned after shrinkage of the tumor. Adenocarcinoma of the lung is very rarely seen in teenagers or children, especially in the absence of risk factors. © SAGE Publications

High strength/density ratio in a syntactic foam made from one-part mix geopolymer and cenospheres

By designing a composite of one-part mix geopolymer and hollow cenospheres, a commercially viable and environmentally-friendly foam was synthesised with a high strength/density ratio. The composite is made of a dry mix powder of geopolymer source materials, sodium silicate alkali activator and cenospheres, which starts to react when mixed with water. As the geopolymer reacts and gains strength over time, the surface of the cenospheres takes part in the reaction and forms a strong bond with the binding matrix. Synchrotron-based Fourier transform infrared microspectroscopy revealed, for the first time, the chemical bonding interaction of the amorphous interfacial layer between the geopolymer and cenospheres. The resulting foam composite gained a strength of 17.5 MPa at a density of 978 kg/m3, which is noticeably higher than that of existing environmentally-friendly lightweight foams made under ambient conditions. The thermal conductivity of the foam was measured to be around 0.28 kW/mK, which is similar to that of foam concrete. This foam produced in this study is found to be lightweight, strong and possess a desirable insulating capacity, while the preparation process of the one-part mix composite is maintained simply by adding water and curing the mixture at an ambient temperature

Pattern of Deliberate Self-Poisoning in Gorgan, North of Iran

Background: Suicide is a global public health problem. Deliberate Self-Poisoning (DSP) is one of the most common methods of suicide in many countries. This study was designed to identify the trends and characteristics of DSP in Gorgan.Methods: The study was carried out retrospectively in 5 Azar Hospital. It included 549 patients who were hospitalized in the hospital due to DSP from March 2008 to March 2015. Data were obtained from medical records. Stata software and Pearson's chi-squared test were used for data analysis.Results: Of 549 patients, 51% were females and 50.27% were aged 20–29 years. The majority of patients (76.68%) lived in urban areas. Poisoning occurred mostly in summer and the peak was observed in August. Most of the poisoning agents were pharmaceuticals (80.51%). Among the pharmaceuticals, benzodiazepines were involved most often. Overall, 21 patients (3.83%) died. The highest number of deaths was due to aluminum phosphide poisoning (76.19%). In addition, family quarrel was the main cause of DSP (43.17%). There were significant differences between the causes of DSP and demographics. Characteristics including gender, age groups, marital status, employment status and educational status.Conclusion: Deliberate self-poisoning (DSP) with drugs has recently been a serious social problem, especially in the younger generation in Gorgan and there is an urgent need for a prevention plan

Model systems for studying lipid oxidation associated with muscle foods: Methods, challenges, and prospects

Lipid oxidation is a complex process in muscle-based foods (red meat, poultry and fish) causing severe quality deterioration, e.g., off-odors, discoloration, texture defects and nutritional loss. The complexity of muscle tissue -both composition and structure- poses as a formidable challenge in directly clarifying the mechanisms of lipid oxidation in muscle-based foods. Therefore, different in vitro model systems simulating different aspects of muscle have been used to study the pathways of lipid oxidation. In this review, we discuss the principle, preparation, implementation as well as advantages and disadvantages of seven commonly-studied model systems that mimic either compositional or structural aspects of actual meat: emulsions, fatty acid micelles, liposomes, microsomes, erythrocytes, washed muscle mince, and muscle homogenates. Furthermore, we evaluate the prospects of stem cells, tissue cultures and three-dimensional printing for future model system development. Based on this reviewing of oxidation models, tailoring correct model to different study aims could be facilitated, and readers are becoming acquainted with advantages and shortcomings. In addition, insight into recent technology developments, e.g., stem cell- and tissue-cultures as well as three-dimensional printing could provide new opportunities to overcome the current bottlenecks of lipid oxidation studies in muscle

Nanostructural characterization of geopolymers by advanced beamline techniques

This paper presents the outcomes of a series of beamline-based studies, the results of which are combined to provide a more detailed multiscale understanding of the structure and chemistry of geopolymer binders. The range of beamline-based characterization techniques which have been applied to the study of geopolymer binders is increasing rapidly; although no single technique can provide a holistic view of binder structure across all the length scales which are of importance in determining strength development and durability, the synergy achievable through the combination of multiple beamline techniques is leading to rapid advances in knowledge in this area. Studies based around beamline infrared and X-ray fluorescence microscopy, in situ and ex situ neutron pair distribution function analysis, and nano- and micro-tomography, are combined to provide an understanding of geopolymer gel chemistry, nano- and microstructure in two and three dimensions, and the influences of seeded nucleation and precursor chemistry in these key areas. The application of advanced characterization methods in recent years has brought the understanding of geopolymer chemistry from a point, not more than a decade ago, when the analysis of the detailed chemistry of the aluminosilicate binder gel was considered intractable due to its disordered (“X-ray amorphous”) nature, to the present day where the influence of key compositional parameters on nanostructure is well understood, and both gel structure and reaction kinetics can be manipulated through methods including seeding, temperature variation, and careful mix design. This paper therefore provides a review outlining the value of nanotechnology – and particularly nanostructural characterization – in the development and optimization of a new class of environmentally beneficial cements and concretes. Key engineering parameters, in particularly strength development and permeability, are determined at a nanostructural level, and so it is essential that gel structures can be analyzed and manipulated at this level; beamline-based characterization techniques are critical in providing the ability to achieve this goal

Effect of nanosilica-based activators on the performance of an alkali-activated fly ash

This paper assesses the effect of the use of an alternative activator based on nanosilica/MOH (M = K+ or Na+) blended solutions on the performance of alkali-activated fly ash binders. Binders produced with commercial silicate activators display a greater degree of reaction, associated with increased contents of geopolymer gel; however, mortars produced with the alternative nanosilica-based activators exhibited lower water demand and reduced permeability, independent of the alkali cation used. Na-based activators promote higher compressive strength compared with K-based activators, along with a refined pore structure, although K-activated samples exhibit reduced water demand. Zeolite type products are the major crystalline phases formed within these binders. A wider range of zeolites is formed when using commercial silicate solutions compared with the alternative activators. These results suggest that there are variations in the availability of Si in the system, and consequently in the alkalinity, depending on the silicate source in the activator, which is important in determining the nanostructure of the geopolymer gel.This study was sponsored by the Ministerio de Ciencia e Innovacion of Spain (Project GEORES MAT2010-19934 and research scholarship BES-2008-002440), European regional development fund (FEDER), and the Universitat Politecnica de Valencia (Spain). The participation of SAB and JLP was funded by the Australian Research Council (ARC), including partial funding through the Particulate Fluids Processing Centre, a Special Research Centre of the ARC. A special acknowledgement is also due to the Centre of Electron Microscopy of the Universitat Politecnica de Valencia and Pedro Garces from the Universidad de Alicante for support in some experiments.Rodriguez Martinez, ED.; Bernal, SA.; Provis, JL.; Paya Bernabeu, JJ.; Monzó Balbuena, JM.; Borrachero Rosado, MV. (2013). Effect of nanosilica-based activators on the performance of an alkali-activated fly ash. Cement and Concrete Composites. 35(1):1-11. doi:10.1016/j.cemconcomp.2012.08.025S11135