Adsorption studies of non-ionic surfactants at different vegetable oil-water interfaces

The adsorption studies of non-ionic surfactants (tween 20, tween 40 and tween 80) were conducted at olive oil-water, sunflower oil-water and corn oil-water interfaces by ring detachment method with a du Nouy Tensiometer at 20 °C. A decrease in interfacial tension with an increase in surfactant concentration was observed at all the oil-water interfaces under investigation. Surface excess was calculated from Gibb’s equation while area per molecule was computed from surface excess. Surface pressure-area curves were plotted to study the states of films formed. On close examination of π-A graphs, it was indicated that all the graphs have three distinct parts. The extreme left portion (a) of the graphs represents condensed state, called solid film region, the curved region (b) of the π-A graphs corresponds to liquid film region, while the gaseous film region (c) is indicated by the shallow right hand part of the curves. The solid film region was more prominent in corn oil-water system while a more distinct gaseous film region was observed in olive oil-water system than in other oil-water systems studied. However, liquid film region was observed in all the systems investigated. The observed difference in the behaviour of surfactants at different vegetable oil-water interfaces could be attributed to the difference in types of interacting forces between the surfactant molecules and various vegetable oil phasesColegio de Farmacéuticos de la Provincia de Buenos Aire

Adsorption studies of non-ionic surfactants at different vegetable oil-water interfaces

The adsorption studies of non-ionic surfactants (tween 20, tween 40 and tween 80) were conducted at olive oil-water, sunflower oil-water and corn oil-water interfaces by ring detachment method with a du Nouy Tensiometer at 20 °C. A decrease in interfacial tension with an increase in surfactant concentration was observed at all the oil-water interfaces under investigation. Surface excess was calculated from Gibb’s equation while area per molecule was computed from surface excess. Surface pressure-area curves were plotted to study the states of films formed. On close examination of π-A graphs, it was indicated that all the graphs have three distinct parts. The extreme left portion (a) of the graphs represents condensed state, called solid film region, the curved region (b) of the π-A graphs corresponds to liquid film region, while the gaseous film region (c) is indicated by the shallow right hand part of the curves. The solid film region was more prominent in corn oil-water system while a more distinct gaseous film region was observed in olive oil-water system than in other oil-water systems studied. However, liquid film region was observed in all the systems investigated. The observed difference in the behaviour of surfactants at different vegetable oil-water interfaces could be attributed to the difference in types of interacting forces between the surfactant molecules and various vegetable oil phasesColegio de Farmacéuticos de la Provincia de Buenos Aire

Adsorption studies of non-ionic surfactants at different vegetable oil-water interfaces

The adsorption studies of non-ionic surfactants (tween 20, tween 40 and tween 80) were conducted at olive oil-water, sunflower oil-water and corn oil-water interfaces by ring detachment method with a du Nouy Tensiometer at 20 °C. A decrease in interfacial tension with an increase in surfactant concentration was observed at all the oil-water interfaces under investigation. Surface excess was calculated from Gibb’s equation while area per molecule was computed from surface excess. Surface pressure-area curves were plotted to study the states of films formed. On close examination of π-A graphs, it was indicated that all the graphs have three distinct parts. The extreme left portion (a) of the graphs represents condensed state, called solid film region, the curved region (b) of the π-A graphs corresponds to liquid film region, while the gaseous film region (c) is indicated by the shallow right hand part of the curves. The solid film region was more prominent in corn oil-water system while a more distinct gaseous film region was observed in olive oil-water system than in other oil-water systems studied. However, liquid film region was observed in all the systems investigated. The observed difference in the behaviour of surfactants at different vegetable oil-water interfaces could be attributed to the difference in types of interacting forces between the surfactant molecules and various vegetable oil phasesColegio de Farmacéuticos de la Provincia de Buenos Aire

The Karachi intracranial stenosis study (KISS) Protocol: an urban multicenter case-control investigation reporting the clinical, radiologic and biochemical associations of intracranial stenosis in Pakistan.

Background: Intracranial stenosis is the most common cause of stroke among Asians. It has a poor prognosis with a high rate of recurrence. No effective medical or surgical treatment modality has been developed for the treatment of stroke due to intracranial stenosis. We aim to identify risk factors and biomarkers for intracranial stenosis and to develop techniques such as use of transcranial doppler to help diagnose intracranial stenosis in a cost-effective manner. Methods/Design: The Karachi Intracranial Stenosis Study (KISS) is a prospective, observational, case-control study to describe the clinical features and determine the risk factors of patients with stroke due to intracranial stenosis and compare them to those with stroke due to other etiologies as well as to unaffected individuals. We plan to recruit 200 patients with stroke due to intracranial stenosis and two control groups each of 150 matched individuals. The first set of controls will include patients with ischemic stroke that is due to other atherosclerotic mechanisms specifically lacunar and cardioembolic strokes. The second group will consist of stroke free individuals. Standardized interviews will be conducted to determine demographic, medical, social, and behavioral variables along with baseline medications. Mandatory procedures for inclusion in the study are clinical confirmation of stroke by a healthcare professional within 72 hours of onset, 12 lead electrocardiogram, and neuroimaging. In addition, lipid profile, serum glucose, creatinine and HbA1C will be measured in all participants. Ancillary tests will include carotid ultrasound, transcranial doppler and magnetic resonance or computed tomography angiogram to rule out concurrent carotid disease. Echocardiogram and other additional investigations will be performed at these centers at the discretion of the regional physicians. Discussion: The results of this study will help inform locally relevant clinical guidelines and effective public health and individual interventions

PdO@CoSe2 composites: efficient electrocatalysts for water oxidation in alkaline media

In this study, we have prepared cobalt selenide (CoSe2) due to its useful aspects from a catalysis point of view such as abundant active sites from Se edges, and significant stability in alkaline conditions. CoSe2, however, has yet to prove its functionality, so we doped palladium oxide (PdO) onto CoSe2 nanostructures using ultraviolet (UV) light, resulting in an efficient and stable water oxidation composite. The crystal arrays, morphology, and chemical composition of the surface were studied using a variety of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It was also demonstrated that the composite systems were heterogeneous in their morphology, undergoing a shift in their diffraction patterns, suffering from a variety of metal oxidation states and surface defects. The water oxidation was verified by a low overpotential of 260 mV at a current density of 20 mA cm(-2) with a Tafel Slope value of 57 mV dec(-1). The presence of multi metal oxidation states, rich surface edges of Se and favorable charge transport played a leading role towards water oxidation with a low energy demand. Furthermore, 48 h of durability is associated with the composite system. With the use of PdO and CoSe2, new, low efficiency, simple electrocatalysts for water catalysis have been developed, enabling the development of practical energy conversion and storage systems. This is an excellent alternative approach for fostering growth in the field.Funding Agencies|Ajman University [2022-IRG-HBS-5]; National Natural Science Foundation of China [NSFC 51402065, 51603053]</p

Investigating the impact of prior COVID-19 on IgG antibody and interferon γ responses after BBIBP-CorV vaccination in a disease endemic population: A prospective observational study

Background and aims: COVID-19 vaccinations have reduced morbidity and mortality from the disease. Antibodies against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) have been associated with immune protection. Seroprevalence studies revealed high immunoglobulin G (IgG) antibody levels to SARS-CoV-2 in the Pakistani population before vaccinations. We investigated the effect of BBIBP-CorV vaccination on circulating IgG antibodies and interferon (IFN)-γ from T cells measured in a cohort of healthy individuals, with respect to age, gender, and history of COVID-19. Methods: The study was conducted between April and October 2021. BBIBP-CorV vaccinated participants were followed up to 24 weeks. Antibodies to SARS-CoV-2 Spike protein and its receptor-binding domain (RBD) were measured. IFNγ secreted by whole blood stimulation of Spike protein and extended genome antigens was determined. Results: Study participants with a history of prior COVID-19 displayed a higher magnitude of IgG antibodies to Spike and RBD. IgG seropositivity was greater in those with prior COVID-19, aged 50 years or younger and in females. At 24 weeks after vaccination, 37.4% of participants showed IFN-γ responses to SARS-CoV-2 antigens. T cell IFN-γ release was higher in those with prior COVID-19 and those aged 50 years or less. Highest IFN-γ release was observed to extended genome antigens in individuals both with and without prior COVID-19. Conclusion: We found that IgG seropositivity to both Spike and RBD was affected by prior COVID-19, age and gender. Importantly, seropositive responses persisted up to 24 weeks after vaccination. Persistence of vaccine induced IgG antibodies may be linked to the high seroprevalence observed earlier in unvaccinated individuals. Increased T cell reactivity to Spike and extended genome antigens reflects cellular activation induced by BBIBP-CorV. COVID-19 vaccination may have longer lasting immune responses in populations with a higher seroprevalence. These data inform on vaccination booster policies for high-risk group

Humoral and T cell responses to SARS-CoV-2 reveal insights into immunity during the early pandemic period in Pakistan

Background: Protection against SARS-CoV-2 is mediated by humoral and T cell responses. Pakistan faced relatively low morbidity and mortality from COVID-19 through the pandemic. To examine the role of prior immunity in the population, we studied IgG antibody response levels, virus neutralizing activity and T cell reactivity to Spike protein in a healthy control group (HG) as compared with COVID-19 cases and individuals from the pre-pandemic period (PP).Methods: HG and COVID-19 participants were recruited between October 2020 and May 2021. Pre-pandemic sera was collected before 2018. IgG antibodies against Spike and its Receptor Binding Domain (RBD) were determined by ELISA. Virus neutralization activity was determined using a PCR-based micro-neutralization assay. T cell - IFN-γ activation was assessed by ELISpot.Results: Overall, the magnitude of anti-Spike IgG antibody levels as well as seropositivity was greatest in COVID-19 cases (90%) as compared with HG (39.8%) and PP (12.2%). During the study period, Pakistan experienced three COVID-19 waves. We observed that IgG seropositivity to Spike in HG increased from 10.3 to 83.5% during the study, whilst seropositivity to RBD increased from 7.5 to 33.3%. IgG antibodies to Spike and RBD were correlated positively in all three study groups. Virus neutralizing activity was identified in sera of COVID-19, HG and PP. Spike reactive T cells were present in COVID-19, HG and PP groups. Individuals with reactive T cells included those with and without IgG antibodies to Spike.Conclusions: Antibody and T cell responses to Spike protein in individuals from the pre-pandemic period suggest prior immunity against SARS-CoV-2, most likely from cross-reactive responses. The rising seroprevalence observed in healthy individuals through the pandemic without known COVID-19 may be due to the activation of adaptive immunity from cross-reactive memory B and T cells. This may explain the more favourable COVID-19 outcomes observed in this population