Effect of Nano Silica De-agglomeration, and Methods of Adding Super-plasticizer on the Compressive Strength, and Workability of Nano Silica Concrete

Nowadays, nano silica appears to be one of the attractive cement substitution alternatives for researchers. Several authors have studied the physical effects of its incorporation on cement, despite of significant inconsistencies in reported results, specially workability and compressive strength of resulting concrete. This paper presents a thorough experimental investigation testing more than 16 concrete mixtures, which covers some of the main reasons of these inconsistencies. One of these problems is the method of applying the nano particles, as they are highly agglomerated, and if applied directly in a bulk composite, they often lose their high-surface area due to grain growth or unavailability of the high surface area where it matters. The presented research investigated how agglomeration can affect the compressive strength, and workability of normal strength concrete. Different methods of de-agglomeration were tested, as sonication, homogenization, and stirring. Besides, optimization of the super plasticizer's addition timing to concrete incorporating nano silica (NS) is elaborately investigated by adding the superplasticizer in different timings of addition; starting by adding NS to superplasticizer and water then applying de-agglomeration method, ending with de-agglomeration of NS alone with portion of water, then adding SP to the other portion of water before application them to the dry components. Results showed that sonication proved to be the most significant de-agglomeration method as it enhanced the gain in compressive strength of concrete by 23% by using only 1% nano silica as cement substitution. Sonication of NS also helped increasing the concrete workability significantly as a result of better dispersion of NS. As for the superplasticizer addition time, sonication of NS alone with portion of water, then adding SP to the other portion of water before application them to the concrete dry components showed a significant performance as compared to the other timings, as the compressive strength reached an increase of 26% compared to the control specimens. Keywords: Nano silica, concrete, plasticizers, agglomeration, workability, strength

Chemical studies of chromanone-thiadiazole, pyridazine and thiosulfin hybrid

3-Chlorochromanon derivatives 4a,b are reacted with hydrazine hydrate to afford 3-hydrazino-2-tetrahydro(pyran or thiopyran)chroman-4-ones 5a,b. Then compound 5a,b is reacted with carbon disulfide and acetylacetone to give 5'-thiolo - 2-tetrahydro(pyrane or thiopyran)- spiro[chroman-3,2'- [1,3,4]-thiadiazole]-4-one 6a,b and 3', 5'-dimethyl- 2-tetrahydro(pyran or thiopyran) spiro [chroman-3,2'- piprazine]-4-one 7a,b, respectively. α-Chlorosulfenyl chlorides 2a,b are treated with thioacetic acid to form α-chloroalkyl disulfides 8a,b, the latter compounds 8a,b were treated with morpholine to furnish a mixture of 1,3,4-oxadithiins 9a,b, 1,3,4,5,6-oxatetrathiocins 10a,b, 1,2,4-trithiolanes 11a,b (cis- and trans-), 1,2,4,5-tetrathiins (cis- and trans-) 12a,b. The formation of the new compounds are confirmed by spectral (IR, 1H NMR, and MS) analysis

Derivatization and biological activity studies of 3-chloro-3-chlorosulfenyl spiro tetrahydropyran/tetrahydrothiopyran-4,2'-chroman-4'-one

1502-1510The adducts 4a,b-7a,b have been obtained either by reducing α-chloro-β-oxosulfenyl chlorides 2a,b with iodide ion in the presence of dienes namely, 2-methyl-1,3-butadiene (isoperene), 2,3-dimethyl-1,3-butadiene, 1,2,3,4- tetrachlorocyclopentadiene, or 1,3-cyclohexadiene, respectively; or by thermolysis of oxadithiin derivatives 3a,b in the presence of the same aforementioned dienes presumably via the formation of the same intermediate A in both cases of compounds 2a,b and 3a,b. It is observed that α-chloro-β-oxosulfenyl chlorides 2a,b undergo straight forward substitution with potassium cyanide to give 8a,b. Direct oxidation of 2a,b with H2O2/AcOH affords 3,3-dichloropyran-4-ones 9a,b, while conversion of 2a,b to the sulfonamides 10a,b followed by oxidation provides 3-chloropyranones 11a,b. Antioxidant and antimicrobial evaluation of compounds 4a,b-6a,b shows moderate activiy. MIC of the derivative 6b reveals a remarkable inhibition of the pathogenic gram positive bacteria (Staphylococcus aureus ) as well as gram negative E coli

Derivatization and biological activity studies of 3-chloro-3-chlorosulfenyl spiro tetrahydropyran/tetrahydrothiopyran-4,2'-chroman-4'-one

The adducts 4a,b-7a,b have been obtained either by reducing α-chloro-β-oxosulfenyl chlorides 2a,b with iodide ion in the presence of dienes namely, 2-methyl-1,3-butadiene (isoperene), 2,3-dimethyl-1,3-butadiene, 1,2,3,4-tetrachlorocyclopentadiene, or 1,3-cyclohexadiene, respectively; or by thermolysis of oxadithiin derivatives 3a,b in the presence of the same aforementioned dienes presumably via the formation of the same intermediate A in both cases of compounds 2a,b and 3a,b. It is observed that α-chloro-β-oxosulfenyl chlorides 2a,b undergo straight forward substitution with potassium cyanide to give 8a,b. Direct oxidation of 2a,b with H2O2/AcOH affords 3,3-dichloropyran-4-ones 9a,b, while conversion of 2a,b to the sulfonamides 10a,b followed by oxidation provides 3-chloropyranones 11a,b. Antioxidant and antimicrobial evaluation of compounds 4a,b-6a,b shows moderate activiy. MIC of the derivative 6b reveals a remarkable inhibition of the pathogenic gram positive bacteria (Staphylococcus aureus ) as well as gram negative E coli.

Impact of Ramadan focused education program on hypoglycemic risk and metabolic control for patients with type 2 diabetess

Background: Fasting during the month of Ramadan could lead to acute complications and increased hypoglycemic risk of patients with type 2 diabetes. Therefore, diabetes is one of the diseases that need careful observation and special considerations during Ramadan including patients’ education and counseling. Objectives: To evaluate the impact of Ramadan focused education program on acute complications and biomedical parameters. Methods: A prospective nonrandomized interventional controlled design was run on three phases: before, during, and after Ramadan on 262 type 2 diabetes patients. The intervention group (n=140) received focused individualized diabetic education sessions and antidiabetic medications adjustment before and after Ramadan, while the control group (n=122) received standard diabetic care. A validated hypoglycemia questionnaire was used in both groups to assess the change of the risk. Patients were advised to adjust the dosage and timing of antidiabetic agents according to the recommendations for management of diabetes during Ramadan. Primary outcomes were postintervention change of hypoglycemia score and HbA1c over 6-month follow-up. Data were presented as mean ± standard deviation. HbA1c was expressed in percentage. Results: The hypoglycemic scores before, during, and after Ramadan were 14.21±8.50, 6.36±6.17, and 5.44±5.55 in the intervention group, respectively (P,0.001) and 14.01±5.10, 13.46±5.30, and 9.27±4.65 in the control group, respectively (P,0.001). HbA1c levels were 9.79±1.89, 8.26±1.54, and 8.52±1.61 before, during, and after Ramadan in the intervention group, respectively (P,0.001), and 10.04±1.47, 9.54±1.38, and 9.59±1.79 in the control group, respectively (P,0.001). Post-Ramadan reductions of HbA1c and hypoglycemic scores were significantly higher in the intervention group (-13.0% vs -4.5%, P=0.004 for HbA1c and -61.7% vs -33.8%, P,0.001 for hypoglycemic score). Low-density lipoprotein cholesterol improved in the intervention group from 2.41±0.91 mmol/L before Ramadan to 2.28±0.68 mmol/L after Ramadan (P,0.001). No statistically significant effects were observed on blood pressure or body weight in the intervention group. Also, no change was observed in the control group. Conclusion: Ramadan educational program had a positive impact with reduction of hypoglycemic risk, HbA1c, and low-density lipoprotein cholesterol. Therefore, it could be recommended for patients with increased risk of hypoglycemia during Ramadan fasting

Defining criteria for disease activity states in systemic juvenile idiopathic arthritis based on the systemic Juvenile Arthritis Disease Activity Score

Objective To develop and validate cutoff values in the systemic Juvenile Arthritis Disease Activity Score 10 (sJADAS10) that distinguish the states of inactive disease (ID), minimal disease activity (MiDA), moderate disease activity (MoDA), and high disease activity (HDA) in children with systemic juvenile idiopathic arthritis (sJIA), based on subjective disease state assessment by the treating pediatric rheumatologist. Methods The cutoffs definition cohort was composed of 400 patients enrolled at 30 pediatric rheumatology centers in 11 countries. Using the subjective physician rating as an external criterion, 6 methods were applied to identify the cutoffs: mapping, calculation of percentiles of cumulative score distribution, Youden index, 90% specificity, maximum agreement, and ROC curve analysis. Sixty percent of the patients were assigned to the definition cohort and 40% to the validation cohort. Cutoff validation was conducted by assessing discriminative ability. Results The sJADAS10 cutoffs that separated ID from MiDA, MiDA from MoDA, and MoDA from HDA were ≤ 2.9, ≤ 10, and > 20.6. The cutoffs discriminated strongly among different levels of pain, between patients with or without morning stiffness, and between patients whose parents judged their disease status as remission or persistent activity/flare or were satisfied or not satisfied with current illness outcome. Conclusion The sJADAS cutoffs revealed good metrologic properties in both definition and validation cohorts, and are therefore suitable for use in clinical trials and routine practice

Mapping geographical inequalities in access to drinking water and sanitation facilities in low-income and middle-income countries, 2000-17

Background: Universal access to safe drinking water and sanitation facilities is an essential human right, recognised in the Sustainable Development Goals as crucial for preventing disease and improving human wellbeing. Comprehensive, high-resolution estimates are important to inform progress towards achieving this goal. We aimed to produce high-resolution geospatial estimates of access to drinking water and sanitation facilities. Methods: We used a Bayesian geostatistical model and data from 600 sources across more than 88 low-income and middle-income countries (LMICs) to estimate access to drinking water and sanitation facilities on continuous continent-wide surfaces from 2000 to 2017, and aggregated results to policy-relevant administrative units. We estimated mutually exclusive and collectively exhaustive subcategories of facilities for drinking water (piped water on or off premises, other improved facilities, unimproved, and surface water) and sanitation facilities (septic or sewer sanitation, other improved, unimproved, and open defecation) with use of ordinal regression. We also estimated the number of diarrhoeal deaths in children younger than 5 years attributed to unsafe facilities and estimated deaths that were averted by increased access to safe facilities in 2017, and analysed geographical inequality in access within LMICs. Findings: Across LMICs, access to both piped water and improved water overall increased between 2000 and 2017, with progress varying spatially. For piped water, the safest water facility type, access increased from 40·0% (95% uncertainty interval [UI] 39·4–40·7) to 50·3% (50·0–50·5), but was lowest in sub-Saharan Africa, where access to piped water was mostly concentrated in urban centres. Access to both sewer or septic sanitation and improved sanitation overall also increased across all LMICs during the study period. For sewer or septic sanitation, access was 46·3% (95% UI 46·1–46·5) in 2017, compared with 28·7% (28·5–29·0) in 2000. Although some units improved access to the safest drinking water or sanitation facilities since 2000, a large absolute number of people continued to not have access in several units with high access to such facilities (>80%) in 2017. More than 253 000 people did not have access to sewer or septic sanitation facilities in the city of Harare, Zimbabwe, despite 88·6% (95% UI 87·2–89·7) access overall. Many units were able to transition from the least safe facilities in 2000 to safe facilities by 2017; for units in which populations primarily practised open defecation in 2000, 686 (95% UI 664–711) of the 1830 (1797–1863) units transitioned to the use of improved sanitation. Geographical disparities in access to improved water across units decreased in 76·1% (95% UI 71·6–80·7) of countries from 2000 to 2017, and in 53·9% (50·6–59·6) of countries for access to improved sanitation, but remained evident subnationally in most countries in 2017. Interpretation: Our estimates, combined with geospatial trends in diarrhoeal burden, identify where efforts to increase access to safe drinking water and sanitation facilities are most needed. By highlighting areas with successful approaches or in need of targeted interventions, our estimates can enable precision public health to effectively progress towards universal access to safe water and sanitation