Use of polymerizable porogens (PolyPo), wherein the porogenic segment is linked to the polymerizable moiety either via a readily cleavable covalent bond or it is electrostatically bound as a ...counterion, was earlier shown by us to be an effective strategy for the preparation of porous polymers with a high density of functional groups lining the internal pore walls. The pore size was shown to vary with the size of the porogenic segment in both cases. Here, we examine the possibility to tune the pore size by mixing multiple pore-forming agents during polymerization. Three types of systems were studied: (i) the PolyPo, St-PEG-350, was mixed with varying amounts of free MPEG350 and polymerized in the presence of 50 wt % of divinyl benzene (DVB); (ii) St-PEG-350 was mixed with free MPEG of different molecular weights, namely, MPEG350, MPEG750, and MPEG-2000, and polymerized in the presence of 50 wt % of DVB; and (iii) a mixture of equal weights of two PolyPos, carrying MPEG segments of different molecular weights, was polymerized in the presence of 50 wt % of DVB. BET nitrogen adsorption and electron microscopy studies reveal an intricate interplay of several factors, namely, the relative amounts of the two porogenic components, their relative sizes, and finally whether the second component is an inert additive or another PolyPo influences the outcome. In summary, these systems provide an alternate strategy to regulate the nature of the porous polymer without having to resort to the synthesis of additional PolyPos. Finally, we explore an exciting possibility of preparing mesoporous monoliths, carrying both amine and carboxylic acid groups, in a single step; here, polymerization of DVB was done in the presence of a covalently linked PolyPo (source of amine) and an ionic PolyPo (source of carboxylic acid). It was noticed that the porogenic segments of the two porogens do not collocate but microphase-separate independently during the polymerization and hence leave behind amines and acid groups in distinct pores within the same matrix; this approach opens up an opportunity to design multifunctional catalytic matrices.
The invasive nature of water hyacinth and the need for renewable energy sources have necessitated this research. Catalyst development through enhanced pore structure and process parameters ...optimization are requirements for effective mass transport during the biomass valorization and improved biocrude formation during solvothermal liquefaction process. In this present study, the effects of temperature (250–340 °C), residence time (10–20 min) and catalyst loading (10–13 wt%) on biocrude, biochar, gas yield, and biomass conversion were optimized using a Box-Behnken experimental design. The developed catalyst through the application of polytetrafluoroethylene (PTFE) for pore structure enhancement was characterized using SEM, BET and XRD techniques. The process optimization found maximum biocrude yield (32.0 wt%), minimum biochar yield (19.4 wt%) and maximum conversion efficiency (80.6%) at 340 °C, 20 min residence time, and 13 wt% catalyst loading. The GC-MS result of the biocrude produced at the optimum conditions (13 wt% catalyst loading) consists of ketones (32.2%), acids (22.3%) and had 65.2% carbon, 7.3% hydrogen, HHV of 29.4 MJ/kg and H/C ratio of 1.34 while an increment in catalyst loading of 20 wt% enhanced the overall biocrude properties with HHV of 35.50 MJ/kg. This result depicts the suitability of the PTFE modified acid treated kaolin for high quality biocrude production through valorization of water hyacinth into a candidate for renewable energy material.
Display omitted
•Water hyacinth was valorized in ethanol: acetone medium under PTFE-induced catalyst for the first time.•The optimum reaction conditions of 340 °C, 20 mins and 13 wt% catalyst loading yielded 31.98 wt% biocrudes.•20 wt% catalyst loading enhanced the HHV (35.5 MJ/kg) and reduces the oxygen content (12.89%).•High selectivity to 2-Pentanone, 4-hydroxy-4-methyl- with 23.86 area % was obtained at 13 wt% catalyst loading..
Functionalized carbon dots (CDs) exhibit intriguing photo-exciton dynamics. CDs can donate or accept electrons depending on their functional groups and electrostatic characteristics. We exploited the ...electron-accepting capability of nitrogen-doped graphitic carbon dots (N-g-CDs) to improve the charge-carrier separation of the polymeric carbon nitride (PCN) photocatalyst. l-Aspartic acid pyrolyzed at 320 °C yielded ∼25 nm size N-g-CDs that were embedded with PCN. The in-plane infiltration of nanosized N-g-CDs increased the surface area of PCN from 11.5 to 104.9 m2 g–1. The N-g-CDs/PCN hybrid catalyst tested for photocatalytic chromium reduction evidenced about a 3-fold higher rate than PCN. Also, the antibiotic tetracycline and rhodamine B dye rapidly degraded with faster degradation kinetics. The carrier dynamic analysis and computational investigations suggest that the electron acceptor feature of N-g-CDs governs the effective separation of photo-excitons and the high surface area of N-g-CDs/PCN contributes to photoactivity enhancement. This study offers insights into designing high-performance metal-free photocatalysts for water treatment applications.
Introduction: Children's oral health is a vital part of their overall general health. Early first dental visit can influence the child's future oral health. The objective of this study was to assess ...the average age, reason, and caries status of children on their first dental visit at a tertiary care center in Kathmandu. Methods: A cross-sectional observational study was conducted among the children aged upto 14 years visiting the outpatient departments of Kantipur Dental College. A Validated questionnaire was provided to the parents visiting with the child and dental checkup was carried out in their first dental visit. Results: Out of 334 children a total of 43 (12.9%) visited by 3 years of age and only 9 (2.7%) children visited by 1 year of age. Majority of children were of age 4-6 years (n=127) with a mean age of 6.71±2.95. Most common chief complaint for their first dental visit was decayed tooth (n=95, 28.4%), followed by pain (n=93, 27.8%) and 4 of them (1.2%) visited for routine checkup. Conclusion: The majority of the children make their first dental visit too late. Children delaying their first dental appointment had much greater dental caries experience. Dental caries and associated complications were the primary reasons for the child's first dental appointment.
Introduction: The prediction of mesiodistal widths of unerupted canines and premolars are an important aspect of analysis of the developing permanent dentition. Various radiographic as well as non ...radiographic methods have been tested and researched to predict the width of these teeth. The Moyers mixed dentition analysis is a universally accepted technique. Whereas Aboul-Azm and Fouda’s approach of mixed dentition analysis is a concept that derives the measurement from equation based on the buccolingual width of the permanent first molars. It does not require any table for the prediction.
Objective: The present study compares the Aboul-Azm and Fouda’s approach of mixed dentition analysis with Moyers technique.
Methodology: Estimations of the widths of the unerupted permanent canines, first and second premolars were performed for maxillary and mandibular arches using Aboul-Azm and Fouda’s and Moyers prediction methods. The predicted values were then compared with the measurements of the actual teeth on 224 study models of males and females. The study was conducted from October to December 2021.
Results: The study was conducted on 112 male and female samples each. For males, statistically significant underestimation were found for Aboul-Azm and Fouda’s method in both arches whereas Moyers method showed better accuracy in males. In females Moyers method showed a significant overestimation. In the total sample the Moyers method showed accuracy for maxillary arch whereas Aboul-Azm and Fouda’s method was more accurate for the mandibular arch.
Conclusion: Moyers method showed a good accuracy in the maxillary arch while in the mandibular arch Aboul-Azm and Fouda’s method was more accurate.
Serum, saliva and urine samples of 25 clinically and radiologically diagnosed cystic echinoccosis (CE) patients, 25 clinically suspected cases of CE, 15 other parasitic disease controls and 25 ...healthy controls were evaluated for anti-hydatid antibody response by ELISA. The sensitivity of serum, saliva and urine was found to be 72, 56 and 84%, respectively, while specificity was 76% in all the samples. Urine showed significantly higher (
p
<
0.05) sensitivity than that of saliva samples but not significantly higher (
p
>
0.05) than that of serum samples. There was no significant difference in the immune response of patients with hepatic versus extrahepatic cysts and single versus multiple cysts. Thus, biological fluid like urine may be used as an alternative or as an adjunct to serum samples by virtue of its non-invasive, easy collection and similar sensitivity and specificity.
Background and Aims: Acute rheumatic fever and rheumatic heart disease constitute an important public health problem in the developing countries. The disease results from an abnormal autoimmune ...response to a group A streptococcal infection in a susceptible host. We aim to describe the pattern of valvular involvement in patients taking Injection Benzathine Penicillin.Methods: All the patients, who were taking injection Benzathine penicillin during 15th April to 14th July, 2013 at our Centre, were included in this study. Demographic features like age, sex, echocardiographic diagnosis along with any adverse effects of Benzathine penicillin were collected.Results: A total of 661 patients were included in our study, out of which female predominated in numbers. Rheumatic heart disease rather than rheumatic fever was the cause for Penicillin injection. Mitral valve was the most common valve involved and it was more common in female.Pure mitral stenosis was the most common valvular involvement. Forty two percent patients underwent intervention; among them Percutaneous transluminal mitral commisuorotomy was the most common. There was no adverse event during the study time following penicillin injection.Conclusions: Women are more commonly affected than male. Mitral valve is the most common valve involved. Nepalese Heart Journal 2016; 13(2): 25-27
PDF
