Friedel’s Salt and Hydrotalcite – Layered Double Hydroxides and the Protection against Chloride Induced Corrosion

This paper discusses some aspects of corrosion protection that fly ash and GGBFS offer to steel reinforcement in concrete. It focuses on the formation of two types of Layered Double Hydroxides (LDH’s). These are Friedel’s salt and Hydrotalcite. While Friedel’s salt is known to form in fly ash blends, the authors support the evidence of hydrotalcite formation in GGBFS blends as a result of the magnesium content in the slag. The paper discusses the corrosion protection performance of GGBFS concrete and compares it to that of fly ash concrete. The paper shows the superior advantage of including GGBFS for corrosion protection. The authors explored the probable reasons for this significant advantage and relate it to the formation of hydrotalcite in GGBFS concretes

A growth selection system for the directed evolution of amine forming or converting enzymes

Fast screening of enzyme variants is crucial for tailoring biocatalysts for the asymmetric synthesis of non natural chiral chemicals, such as amines. However, most existing screening methods either are limited by the throughput or require specialized equipment. Herein, we report a simple, high throughput, low equipment dependent, and generally applicable growth selection system for engineering amine forming or converting enzymes and apply it to improve biocatalysts belonging to three different enzyme classes. This results in i an amine transaminase variant with 110 fold increased specific activity for the asymmetric synthesis of the chiral amine intermediate of Linagliptin; ii a 270 fold improved monoamine oxidase to prepare the chiral amine intermediate of Cinacalcet by deracemization; and iii an ammonia lyase variant with a 26 fold increased activity in the asymmetric synthesis of a non natural amino acid. Our growth selection system is adaptable to different enzyme classes, varying levels of enzyme activities, and thus a flexible tool for various stages of an engineering campaig

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Effect of NaOH activation on sulphate resistance of GGBFS and binary blend pastes

This paper presents an investigation into the observed enhanced performance that alkali activated ground granulated blast furnace slag (GGBFS) and binary blends offer against sulphate attack. X-ray diffraction (XRD) was carried out to identify and quantify the crystalline phases formed in a wide range of GGBFS and GGBFS-OPC (ordinary Portland cement) blends. Furthermore, specimens were exposed to a sulphate solution to examine the evolution of compressive strength along with identification of activation and/or hydration products. XRD demonstrated that ettringite was completely decomposed into its constituents in the presence of NaOH while quantification ascertained the formation of considerable amounts of hydrotalcite in the activated GGBFS and binary blends. Alkali activated GGBFS and binary blends specimens with higher GGBFS content offered enhanced resistance against aggressive sulphate ions and no significant degradation products were observed in these specimens after 6 months of exposure to sulphate solution. The results demonstrated that hydrotalcite formation may be a major reason for the improved sulphate resistance of alkali activated GGBFS and binary blend pastes with higher GGBFS conten

Chloride binding capacity of hydrotalcite and the competition with carbonates in ground granulated blast furnace slag concrete

This paper further investigates the hypothesis and recent preliminary findings that hydrotalcite is responsible for the remarkable improvement of chloride binding in concretes containing ground granulated blast furnace slag (GGBFS). In this paper, the chloride binding capacity of hydrotalcite has been examined in a wide range of GGBFS and GGBFSOPC (ordinary Portland cement) blends. X-ray diffraction (XRD) was conducted to identify hydrotalcite in GGBFS pastes and to distinguish it from Friedel’s salt. Using Rietica software for quantifying crystalline minerals, this paper presents quantified XRD analysis of the relative proportion of hydrotalcite formed in GGBFS and binary blend pastes. XRD revealed that hydrotalcite was formed in all pastes containing GGBFS. The results clearly demonstrated that hydrotalcite made up a significant proportion of the crystalline phase in GGBFS pastes. The results further showed that the ability of hydrotalcite to bind chlorides was not significantly impaired by the competitive adsorption of carbonates

Anthropogenic impact on the distribution of the birds in the tropical thorn forest, Punjab, Pakistan

The present research was conducted to assess the anthropogenic impacts on avian diversity around the river Chenab, Pakistan. The avian diversity was recorded on different landscapes along the river Chenab, that is, forest, agricultural, rural, and urban habitats. The data on diversity and distribution of various avian species were collected through linear count along with direct count methods viz. personal observations and sound records and indirect count methods viz. presences of carcasses and meeting with local communities. The habitat preferences of birds varied significantly. A decline in avian diversity was observed from forest habitat to urban landscapes. One year of bird surveys compiled a total of 150 species from all habitats along the river Chenab. Computed statistical data show that Shannon's index provides a quantitative report of diversity which was highest at forest habitat (4.261) followed by rural forest habitat (3.746), agri–rural habitat (3.746), agriculture habitat (3.623), WLH (2.723), urban vegetative habitat (3.215), and very least at urban nonvegetative habitat (2.247). It can be concluded from the present study that many of the avian species have specific habitats and also noted that corridors and connections among different landscapes are important for the conservation of avian diversity