Meti shell contains calcium carbonate which can be calcined into CaO and used as a heterogeneous catalyst in biodiesel synthesis. This study evaluated the ability of CaO catalyst from Meti shell with ...concentrations of 1, 2, 3, 4, and 5% for the synthesis of biodiesel from Moringa seed oil at various transesterification times (1, 2, 3, and 4 hours). The presence of CaO in the Meti shell was indicated by diffraction at 2θ angles of 32.47o , 37.74o , 54.22o , 64.65o , and 67.67oC. Utilizing CaO 3% and a transesterification reaction time of 3 hours resulted in an Rf value corresponding to the standard biodiesel Rf ranges, i.e. 0.69 and 0.66, respectively. The synthesized biodiesel has the highest methyl oleate content of 59.16% with characteristics that have met Indonesian National Standard (SNI 04-7182-2006), including water content of 0.004%, an acid number of 0.06 mg KOH/g, saponification number 273.6 mgKOH/g, iodine number 78.678 g iodine/100 g, the cloud point is 10oC, the pour point is 21oC, however, the cetane number is still below the minimum number of 51.
The aim of this study was synthesis a catalyst applied to the cracking reaction and to characterize its physical-chemical properties. The catalyst is a zirconia-pillared bentonite with Nickel as a ...support metal (promotor). The catalyst is synthesized by pillarization bentonite with ZrOCl2*8H2O as a pillaring agent and then a calcination process for obtaining a zirconia pillared bentonit (ZrO2-bentonite). To obtain a catalyst with good cracking and hydrogenation activity, nickel metal (2% w/w) impregnation was performed using Ni(NO3)2*6H2O precursors. The next step is calcination and reduction to obtain a zirconia-pillared bentonite catalyst with Ni as a support metal (Ni/ZrO2-bentonite). To know the physical-chemical properties was characterized by XRF, XRD, acid properties test using ammonia absorption technique, FTIR and BET. The characterization results with XRF showed an increase of nickel metal content after impregnation process of 6.45%. The acidity assay with ammonia absorption technique showed an increase in the acid properties of the catalyst sample after pillarization and impregnation of 7.580 mmol/g. Analysis of sample diffraction patterns with XRD shows typical montmorillonite peaks still visible but shifts toward an angle of 2θ < 5°. Analysis of functional groups of catalyst with FTIR showed characteristic for Brǿnsted acid at wave number 1635.64 cm-1 after impregnation with nickel metal. Surface area analysis results show an increase in specific surface area after pillarization and impregnation of 96.307 m2/g.
Polyvinyl alcohol and polyvinyl pyrrolidone (PVA–PVP) blended hydrogel for wound dressing has been prepared by using gamma rays irradiation technique. The gel fraction, mechanical properties, the ...water content and water absorption performance of the hydrogels were measured. It was found that the gel fraction increases with increasing irradiation dose but never reaches 100% of gel. The PVA/PVP blended hydrogel has a water content in the range between 60% and 80% and water absorption between 40% and 250%. The water vapor transmission rate value (WVTR) of the PVA/PVP blended hydrogel varies between 50 and 200
g/m
2/h. The hydrogel could be considered as good barrier against microbes. According to in vitro assessment it was found that the PVA/PVP blended hydrogel was very useful material that can meet the efficacy requirement and its healing rate was comparable with sterilized gauze and sofratulle.
•The incidence of positive SARS-CoV-2 cases was 1.9% among the children tested in North Sumatra, Indonesia.•The predominant age group of children with COVID-19 was 6–11 years.•Public holidays and the ...introduction of a new variant contributed to an increase in cases.•Children accounted for a much higher proportion of general SARS-CoV-2 infection.
The aim of the study was to describe the epidemiology of coronavirus disease 2019 (COVID-19) cases in children in North Sumatra Province during the period June 2020 to July 2021.
This study included samples from children in North Sumatra Province aged 0–17 years, suspected to have COVID-19. A case of COVID-19 was confirmed by RT-PCR in the Microbiology Laboratory, Faculty of Medicine, Universitas Sumatera Utara, Indonesia. Data were collected from June 2020 to July 2021. Demographic data including age, sex, and date of diagnosis were collected. A descriptive statistical analysis was performed, and ratios or percentages were compared.
A total of 117 650 people were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and 2222 (1.9%) children were positive. The age group 6-11 years had the highest proportion of cases with 679/2222 cases (30.6%). Overall, the number of positive COVID-19 cases peaked in July 2021, with 650 cases and a positivity rate of 3.0%. In 2020, the greatest proportion of cases occurred in the age group of 12–14 years; however, this changed to the age group 6-11 years in 2021.
COVID-19 was detected in all paediatric age groups in North Sumatra during the study period. Incidence peaks occurred due to mass gatherings, public holidays, and the introduction of a new variant in Indonesia. Children accounted for a much higher proportion of SARS-CoV-2 infection compared to those reported in other studies and could have played a role as the source of transmission in society.
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