Mechanical Properties and Microstructure of a Metakaolin-Based Inorganic Polymer Mortar Reinforced with Quartz Sand

Silicon - The synthesis, mechanical behaviour, and microstructure of metakaolin-based geopolymer mortar reinforced with quartz sand are presented in this investigation. Fine sand (quartz sand)...     

Acute hemodialysis complications in end‐stage renal disease patients: The burden and implications for the under‐resourced Sub‐Saharan African health systems

Little is known about the challenges of routine renal replacement therapy in Sub‐Saharan Africa. We investigated the fatal and nonfatal acute hemodialysis (HD) complications in patients with end‐stage renal disease (ESRD) in two main dialysis centers in Cameroon. 1000 consecutive HD sessions incurred over a 4‐month period by 129 patients (96 men, 74%) with ESRD, receiving two weekly HD sessions of 4 hours each, were considered. Personal and clinical profiles before, during, and within 24 hours after HD sessions were used to diagnose complications. Participants were aged 7 to 80 years (mean 46 years). In all, 452 acute complications were recorded in 411 (41%) of the 1000 HD sessions. Of the 11 types of complications, hypotension (25%), muscular cramps (22%), hypertensive crisis (14%), pruritus (10%), and fever (7%) were the most frequent. Three hundred and six complications (67.7%) occurred during understaffed nighttime. The vascular access was the main bleeding site with 64%. Being diabetic and ultrafiltration rate >1000 mL/h were associated with hypotension and muscle cramps. The shorter duration in dialysis was associated with the risk of bleeding and the disequilibrium syndrome while longer duration was associated with muscle cramps. Four deaths (three from bleeding and one from disequilibrium syndrome) occurred, all during nighttime. Nearly half of dialysis sessions in these settings are associated with acute complications, some of which are fatal. Those complications occurred mostly during understaffed periods. Urgent strategies are needed to quickly solve the human capital crisis in the health care sector.     

Bidirectional Conversion Between 3-Monochloro-1,2-propanediol and Glycidol in Course of the Procedure of DGF Standard Methods

NMR observation revealed that bidirectional conversion occurred between 3-monochloropropane-1,2-diol (3-MCPD) and glycidol in the course of the analytical procedure of DFG standard method C-III 18 (09), option A; 3-MCPD was partly converted to glycidol at the transesterification step, and glycidol was converted partly to 3-MCPD at the derivatization step conducted at 80 °C under acidic condition in the presence of NaCl. Based on the proton numbers observed by ¹H NMR, the degrees of the conversion were estimated to be 37 and >70%, respectively. In addition, epoxide ring-opening of glycidol and its esters was found to be ca. 90% by the acid treatment described in the method, option B. Thus, it was concluded that the standard method, option A, did not correctly give the combined amount of 3-MCPD esters and glycidyl esters in oils containing glycidyl esters, and the difference of the values obtained by options A and B did not correspond to the amount of glycidyl esters, either. In addition, derivatives of 3-MCPD with phenylboronic acid were not observed by NMR at the derivatization step, although they were detected by GC-MS in the organic phase at the following extraction step.     

2-Monochloro-1,3-propanediol (2-MCPD) Dynamics in DGF Standard Methods and Quantification of 2-MCPD

Pure 2-monochloro-1,3-propanediol (2-MCPD) was successfully synthesized, identified, and first quantified by the Deutsche Gesellschaft für Fettwissenschaft (DGF) standard method C-VI 18 (10), with a calculable detection sensitivity relative to 3-monochloro-1,2-propanediol (3-MCPD) of 3.26-fold, using a QP-2010 GC/MS instrument. The detection sensitivities of other GC/MS instruments can be determined using the individual ion-ratio of the fragment to the precursor of 3-MCPD-d ₅ as a reference. Quantification of 2-MCPD is possible using conventional 3-MCPD-d ₅ esters as internal-standards, without a calibration curve of pure 2-MCPD. The dynamics of 2-MCPD during DGF standard methods C-VI 18 (10) were directly analyzed using NMR and indirectly using GC/MS. 2-MCPD was partly converted to glycidol under basic conditions of the transesterification step, and the glycidol was reconverted to 2-MCPD under acidic conditions of the extraction step. 2-MCPD spiked in soybean oil was detected as 98 mol% 2-MCPD and 2 mol% 3-MCPD from the area ratio in GC/MS. In contrast, glycidyl stearate spiked in soybean oil was detected as 5.5–5.7 mol% 2-MCPD and 94.3–94.5 mol% 3-MCPD from the corrected area ratio in GC/MS.     

Proteome Analysis of Whole-Body Responses in Medaka Experimentally Exposed to Fish-Killing Dinoflagellate Karenia mikimotoi

Karenia mikimotoi is a well-known harmful algal bloom species. Blooms of this dinoflagellate have become a serious threat to marine life, including fish, shellfish, and zooplanktons and are usually associated with massive fish death. Despite the discovery of several toxins such as gymnocins and gymnodimines in K. mikimotoi, the mechanisms underlying the ichthyotoxicity of this species remain unclear, and molecular studies on this topic have never been reported. The present study investigates the fish-killing mechanisms of K. mikimotoi through comparative proteomic analysis. Marine medaka, a model fish organism, was exposed to K. mikimotoi for a three-part time period (LT₂₅, LT₅₀ and LT₉₀). Proteins extracted from the whole fish were separated by using two-dimensional gel electrophoresis, and differentially expressed proteins were identified with reference to an untreated control. The change in fish proteomes over the time-course of exposure were analyzed. A total of 35 differential protein spots covering 19 different proteins were identified, of which most began to show significant change in expression levels at the earliest stage of intoxication. Among the 19 identified proteins, some are closely related to the oxidative stress responses, energy metabolism, and muscle contraction. We propose that oxidative stress-mediated muscle damage might explain the symptoms developed during the ichthyotoxicity test, such as gasping for breath, loss of balance, and body twitching. Our findings lay the foundations for more in-depth studies of the mechanisms of K. mikimotoi’s ichthyotoxicity.     

Improvement of accuracy in quantification of 3‐monochloropropane‐1,2‐diol esters by Deutsche Gesellschaft für Fettwissenschaft standard methods C‐III 18

By Deutsche Gesellschaft für Fettwissenschaft (DGF) standard methods C‐III 18 for the determination of 3‐monochloropropane‐1,2‐diol (3‐MCPD), the minimum limit of detection was lower in the case of actual oil samples compared to the calibration samples. The problem was found to be lied in the low recovery of 3‐MCPD derivatives from the aqueous phase to the organic phase at the extraction step of the standard procedure. The substitution of the conventional solvent, n‐hexane, with n‐butanol, chloroform, and ethyl acetate increased the recovery to the relative extent of 5.6, 4.7, and 3.9, respectively. The modification contributed to improve the accuracy of the method, especially at lower concentration (<1 ppm) of 3‐MCPD. Practical applications: This paper provides the modification of DGF standard methods C‐III 18 in order to improve the accuracy to quantify 3‐MCPD at lower concentration. It might be important for estimation and control of our daily intake of 3‐MCPD, and for the product control in the fat and oil processing.     

Estimation of the Intestinal Absorption and Metabolism Behaviors of 2- and 3-Monochloropropanediol Esters

The regioisomers of the di‐ and mono‐oleate of monochloropropanediol (MCPD) have been synthesized and subsequently hydrolyzed with pancreatic lipase and pancreatin to estimate the intestinal digestion and absorption of these compounds after their intake. The hydrolysates were analyzed by HPLC using a corona charged aerosol detection system, which allowed for the separation and detection of the different regioisomers of the MCPD esters. The hydrolysates were also analyzed by GC–MS to monitor the free MCPD. The results indicated that the two acyl groups of 2‐MCPD‐1,3‐dioleate were smoothly hydrolyzed by pancreatic lipase and pancreatin to give free 2‐MCPD. In contrast, the hydrolysis of 3‐MCPD‐1,2‐dioleate proceeded predominantly at the primary position to produce 3‐MCPD‐2‐oleate. 2‐MCPD‐1‐oleate and 3‐MCPD‐1‐oleate were further hydrolyzed to free 2‐ and 3‐MCPD by pancreatic lipase and pancreatin, although the hydrolysis of 3‐MCPD‐2‐oleate was 80 % slower than that of 3‐MCPD‐1‐oleate. The intestinal absorption characteristics of these compounds were evaluated in vitro using a Caco‐2 cell monolayer. The results revealed that the MCPD monooleates, but not the MCPD dioleates, were hydrolyzed to produce the free MCPD in the presence of the Caco‐2 cells. The resulting free MCPD permeated the Caco‐2 monolayer most likely via a diffusion mechanism because their permeation profiles were independent of the dose. Similar permeation profiles were obtained for 2‐ and 3‐MCPDs.     

Resistance of Alkali-Activated Blended Volcanic Ash-MSWI-FA Mortar in Sulphuric Acid and Artificial Seawater

Silicon - This paper investigates the resistance of alkali-activated binder from volcanic ash (VA) + Municipal Solid Waste Incinerator Fly Ash (MSWI-FA) system exposed into sulphuric...     

Influence of Thermal Activation and Silica Modulus on the Properties of Clayey-Lateritic Based Geopolymer Binders Cured at Room Temperature

Silicon - In this study, a laterite soil which is a locally available material in many parts of the world was used as the aluminosilicate precursor. The main objective of this study is to...     

Effect of Combined Metakaolin and Basalt Powder Additions to Laterite-Based Geopolymers Activated by Rice Husk Ash (RHA)/NaOH Solution

Silicon - The present study deals with the use of locally prepared rice husk ash (RHA)-based sodium silicate for alkaline activation of laterites (uncalcined (LNW) and calcined (LCA)). RHA-based...