Gel Precipitation Research Articles

Enhanced photovoltaic efficiency in TiO2-based CdS quantum dot-sensitized solar cells by the introduction of ZnO:Al3+ nanoparticles

A technique to fabricate quantum dots-sensitized solar cells (QDSSCs) based on Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles (NPs) is reported. ZnO nanocubes of around 65 nm were synthesized by the sol–gel precipitation method. ZnO was doped with Al3+ to enhance the photovoltaic efficiency by promoting electron mobility to form an efficient photoelectrode added to TiO2. Current density–voltage (J-V) characterizations indicate that the addition of Al3+ doping in ZnO crystalline structure in the photoelectrode can significantly improve current densities and consequently the photoconversion efficiency (η) of the QDSSCs, achieving maximum η of 3.4 % with five ZnO nanocubes layers with a 0.0005 M Al3+ doping concentration. While with the undoped sample and bare TiO2, the obtained ήs were 2.85 and 1.93 %, respectively. The improved QDSSC photovoltaic performance was attributed to the increased light harvesting due to a large surface area by introducing Al-doped ZnO nanocubes into the available places of the TiO2 lattice. On the other hand, the increased electrical conductivity due to the Al3+ ion doped into the ZnO lattice at the divalent Zn2+ site allows electrons to move readily into the Al-doped ZnO conduction band. Additionally, according to electron lifetime studies, the Al-doped ZnO nanocubes act as a dielectric layer, enhancing the photogenerated charge extraction process due to the introduction of lattice defects, causing intermediate levels to obtain higher electron recombination resistance.

Expression of VP2 protein of novel goose parvovirus in baculovirus and evaluation of its immune effect

Short-beak and dwarfism syndrome (SBDS) is a new disease caused by a genetic variant of goose parvovirus in ducks that results in enormous economic losses for the waterfowl industry. Currently, there is no commercial vaccine for this disease, so it is urgent to develop a safer and more effective vaccine to prevent this disease. In this study, we optimized the production conditions to enhance the expression of the recombinant VP2 protein and identified the optimal conditions for subsequent large-scale expression. Furthermore, the protein underwent purification via nickel column affinity chromatography, followed by concentration using ultrafiltration tube. Subsequently, it was observed by transmission electron microscopy (TEM) that the NGPV recombinant VP2 protein assembled into virus-like particles (VLPs) resembling those of the original virus. Finally, the ISA 78-VG adjuvant was mixed with the NGPV-VP2 VLPs to be prepared as a subunit vaccine. Furthermore, both agar gel precipitation test (AGP) and serum neutralization test demonstrated that NGPV VLP subunit vaccine could induce the increase of NGPV antibody in breeding ducks. The ducklings were also challenged with the NGPV, and the results showed that the maternal antibody level could provide sufficient protection to the ducklings. These results indicated that the use of the NGPV VLP subunit vaccine based on the baculovirus expression system could facilitate the large-scale development of a reliable vaccine in the future.

Silica Based Material as a Potential Adsorbent in Reducing Sterol Glucoside Level in Palm Oil Biodiesel

In recent years, biodiesel has emerged as a popular alternative to fossil fuels due to its superior properties. However, the presence of bioactive compounds, known as sterol glucosides (SGs), in crop-based biodiesel has posed a challenge for producers, as they act as crystal seeds and can cause gel formation or precipitation in cold temperatures. This can lead to issues with the quality of biodiesel during storage or use in vehicle engines. To address this issue, a study was conducted to explore the use of silica-based materials as an adsorbent to reduce SGs concentration in palm oil biodiesel. Natural resources silica material with a size of less than 100 µm was used in the process. The results showed that the use of silica gel led to the removal of 63.09 % of SGs in palm-based biodiesel due to its high surface area (556 m2/g) and porosity (0.79 cm3/g). Fourier transform infrared spectroscopy (FTIR) analysis indicated that the silicate and hydroxyl groups on the adsorbent’s surface were responsible for SGs adsorption. Importantly, the quality of the biodiesel before and after the adsorption treatment met all the specifications of the EN 61214 standard. This research suggests that the use of silica-based materials could be a promising solution for reducing SGs concentration in crop-based biodiesel, and could potentially improve its overall quality.

Antiviral efficacies of neem (Azadirachta indica J.) and scent (Ocimum sanctum L.) leaf meals against Newcastle and infectious bursal disease in broiler chickens

The effects of neem (Azadirachta indica) and scent (Ocimum santum) leaf meals fed singly or in combination on the growth response, haemato-biochemical parameters and their antiviral potencies in broiler chickens were investigated. Two hundred 1-day old Ross 308 unsexed broiler chicks were randomly allotted to 5 treatments, consisting of 5 replicates with 8 birds each. Treatments 1 and 2 were basal diets with no leaf meals, treatments 3, 4 and 5 had the basal diets plus 3% neem leaf meal (NLM), 3% scent leaf meal (SLM) and the blend of 2% NLM + 2% SLM, respectively. Birds in treatments 2-5 were unvaccinated against Newcastle disease and Infectious bursal disease while birds in treatment 1 were vaccinated. On days 21 and 42, blood samples were randomly collected from 2 birds per replicate for haemato-biochemical assay, haemagglutination inhibition and agar gel precipitation tests. Data were subjected to descriptive statistics and ANOVA at p<0.05. At the starter phase, an improved feed conversion ratio (p<0.05) was recorded in birds fed the blend at the starter (1.83) and finisher (1.92) phases and the overall performance (1.88) compared to other treatment groups. The least platelet counts (11.08 ×104/µL) were recorded in birds placed on the blend of 2% neem leaf meal + 2% scent leaf meal while the 3% scent leaf meal group recorded the lowest lymphocyte counts (53.60%). At the finisher phase, lymphocyte counts of birds that received the blend of 2% neem leaf meal + 2% scent leaf meal (63.00%) were higher than the other treatments. In conclusion, birds fed diets supplemented with 3% neem and 3% scent leaf meals singly had haemagglutination inhibition titre values and conferred immunity above the protective threshold against Newcastle disease and produced antibodies against Infectious bursal disease. Birds fed the blend of 2% neem + 2% scent leaf meal diets had improved overall performance.

Iron Stress Testing of Oilfield Produced Waters and Hydraulic Fracturing Fluids in the Bakken

Friction reducers are a major additive in almost all water-based hydraulic fracturing fluids. Despite the important role they play in friction reduction during hydraulic fracturing, they pose a veritable threat to the permeability of tight reservoirs upon precipitation. In the industry today, the potential for such precipitation is seldom assessed and as a result, an additional contributor to the formation damage problem has been given little attention. In this work, the sensitivity and affinity of friction reducers to very low concentrations of ferric ions are exploited to provide a qualitative assessment of their propensity to precipitate in hydraulically fractured hydrocarbon reservoirs. Representative samples of produced water and a routinely utilized hydraulic fracturing fluid recipe were spiked with 50ppm Iron (III) trichloride and incubated for 24 hours in a water bath at 200 degrees Fahrenheit. The results showed that precipitation of friction reducers in fracturing fluid is highly likely at low concentrations of ferric ions. This precipitate formed turned from yellow to brown color over time upon heating. The test showed presence of fragmented/unfragmented Partially Hydrolyzed Polyacrylamide (PHPAM) in the produced water, with varying degrees of FR gel precipitation depending on the processing treatment given to the water used for hydraulic fracturing. Evidence for the presence of partially hydrolyzed polyacrylamide was demonstrated in one of the produced waters while the rest did not produce any discernable precipitates. The results indicate that formations with lower iron concentrations may be more vulnerable to Fe3+-PHPAM precipitation than those with higher ferric ion concentration. Therefore, to mitigate formation damage through precipitation of FRs during hydraulic fracturing, a routine iron stress test like the one described herein is required on both hydraulic fracturing fluid and produced water to determine the vulnerability of the reservoir to formation damage by fragmented/unfragmented anionic PHPAMs.

Removal of methylene blue in aqueous solution using nanosilica based sorbent from volcanic ash

In this study, a mesoporous nano-SiO2 from Taal volcanic ash was successfully synthesized via sol–gel precipitation method and used effectively as adsorbent of methylene blue in aqueous solution. The silica rich volcanic ash from Taal contains 43.5% SiO2 which is the precursor of nano-SiO2 and characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRD) and Brunauer, Emmett and Teller (BET). The synthesized nano-SiO2 have an average size of 45 nm, surface area of 181.66 m2/g, pore size of 16–25 nm with purity greater than 99.9%. Characteristics bands at 3410 cm−1 attributed to OH- stretching of silanol groups, and a sharp peak at 1067 cm−1 and 801 cm−1 indicating siloxane (-Si-O-Si-) functional groups. XRD analysis revealed an amorphous nature of nano-SiO2 with crystallite size of 2.96 nm. A ∼99.9 % maximum removal was reached at pH 8, adsorbate concentration of 25 mg/L, adsorbent dose of 1.87 g/L at 22.89 min contact time and found to be reusable even after 5 cycles. Adsorption was best explained by Langmuir model having 65.5 mg/g maximum monolayer adsorption capacity. Kinetic studies showed a pseudo 2nd order with R2 of 99.9%.

Potential of goats’ milk from Aceh hybrid and Etawa goats in producing specific anti-S. mutans antibodies as candidate antibodies for caries immunotherapy

Background: Mother goats produce immunoglobulin G (IgG) as a specific antibody in serum, which is then transferred into milk as natural immunity for their children. Based on this, IgG from goat milk has the potential to replace the role of igg from mammalian blood in preventing caries. The goal of this study was to see if goat milk could be used to produce specific antibodies against Streptococcus mutans (S. mutans) as a candidate antibody for caries immunotherapy. Methods: In this study, pregnant goats were divided into two groups: control and treatment. The treatment group received an injection of S. mutans and then received the second injection, which was the administration of antigen added Freud adjuvant complete (booster 1) subcutaneously, and the third injection, which was the administration of antigen added Freud adjuvant complete (booster 1), and antigen added Freud adjuvant incomplete (booster 2). Blood serum was analyzed qualitatively using the Agar Gel Precipitation Test (AGPT) method to determine antibody formation. Furthermore, colostrum and goat milk were analyzed using the Sandwich ELISA method to determine the formation of anti-S mutans IgG in colostrum and goat milk. Results: Pregnant goats that had been given booster 1 and 2 with a dose of antigen + Freud Adjuvant 1.5:0.5 produced anti-S. mutans antibody titers. Normal levels of IgG in goat colostrum range from 40-60 mg/ml while in milk 0.6-7.5 mg/ml and there is a decrease in the concentration of IgG anti-S. mutans in each week. Conclusions: Colostrum and goat milk produced contain IgG-anti S. mutans antibodies that can be used to prevent dental caries.

Simulator Aids Design, Analysis of Acidizing Jobs With Fluoroboric Acid

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 205893, “Novel Simulator for Design and Analysis of Matrix Acidizing Jobs With Fluoroboric Acid in Sandstone Reservoirs,” by Mohammed Qamruzzaman, SPE, Mandeep Khan, and Dhirendra C. Roy, SPE, ONGC, et al. The paper has not been peer reviewed. _ Matrix acidizing with fluoroboric acid (HBF4) has gained special attention because of its deeper penetration of in-situ generated hydrofluoric (HF) acid and stabilization of formation fines by binding them to the pore surface. While numerous mathematical models exist in the literature for design and evaluation of conventional mud acid treatments, few attempts have been made in developing a laboratory-validated model that can do so for fluoroboric acid treatments. The complete paper presents a novel mathematical model that has been developed that takes into account the chemical kinetics and equilibrium aspects of important reactions and fluid flow inside the reservoir rock. Mathematical Modeling Because the complete paper contains numerous equations, it is essential for understanding the authors’ description of their mathematical model. The authors identify three benefits of their approach from a modeling point of view. First, it reduces the total number of chemical reactions taking place, which greatly simplifies computational complexity while maintaining reasonable accuracy. Second, the inclusion of separate chemical reactions for silica gel precipitation may require fixing the average value of stoichiometric coefficients for reactions between HF/hexafluorosilicic acid (H2SiF6) and slow- and fast-reacting minerals. This becomes challenging to do beforehand, especially when different types of clays are present with relatively equal proportions in the reservoir. Third, all resulting nondimensional numbers can be estimated easily by measuring effluent acid concentration during coreflooding. The following assumptions have been incorporated into the model: - The reservoir and core are assumed to be homogeneous and isotropic. - Flow is assumed to be one-dimensional. - All fast-reacting minerals are grouped together as a single fast-reacting mineral. - All slow-reacting minerals are grouped together as single slow-reacting mineral. - The reaction of HF with fast- and slow-reacting minerals is assumed to be first-order with respect to HF. - Changes in porosity are small and diffusion/gravity/thermal effects are neglected. Laboratory Studies Laboratory studies were performed on sandstone core samples from a prominent payzone in northeastern India to generate data for model validation. Core plugs of 1.5-in. diameter were taken from the same block to prevent mineralogical heterogeneities. Samples were characterized with X-ray diffraction (XRD) analysis and porosity measurements. This payzone was selected because it consists of a diverse range of minerals. Thus, a model that can be validated with the coreflooding from this sample could, in principle, apply to any other sandstone reservoir.

РАЗРАБОТКА И ПОИСК ФУНКЦИОНАЛЬНОСТЕЙ НОВЫХ ОРГАНОКРЕМНЕЗЕМНЫХ ГИБРИДНЫХ НАНОКОМПОЗИТОВ С ВКЛЮЧЕНИЕМ БИОПОЛИМЕРОВ ХИТОЗАНА В СИЛОКСАНОВУЮ ОСНОВУ ПРИ ИХ ПРЕОБРАЗОВАНИИ В МОНОДИСПЕРСНЫЕ ЧАСТИЦЫ МЕЗОПОРИСТОГО КРЕМНЕЗЕМА

A new universal approach to the biomimetic synthesis of hybrid organosilicate nanocomposites with texture and functionality good control has been developed, which consists in the use of biomacromolecules as mesogenic templates. The main strategy is to combine the self-association of polysaccharide nanorods with the flexibility of the sol-gel process in the chemistry of siloxane oligomers formed at various pH values of 3, 5, 8. The measured isotherms of low-temperature nitrogen adsorption-desorption by samples obtained at pH 5 and 8 refer to isotherms of type IV (a) characteristic of mesoporous adsorbents. The isotherms are dominated by the triangular hysteresis H2(a), which is due to network effects in ordered mesoporous materials of the SBA-16 and KIT-5 types. The isotherms of the samples obtained at pH 3 are of the hybrid type (I+IV) with the H4 hysteresis inherent in microporous adsorbents with slit-like mesopores between agglomerates of silica particles. It is shown that the control of the textural properties of hybrid nanocomposites and porous silica is possible by changing the temperature of thermal activation of organosilicate samples and the pH value of the silica gel precipitation medium. The advantage of the developed synthesis is the formation of new functionalities on the surface of silica through its heat treatment while maintaining the polysaccharide template either as its own functional basis or as a carbon resource.

Carbon/Mn3O4/SrTiO3 microsphere photocatalyst for the efficient removal of high‐concentration methylene blue from water

AbstractBACKGROUNDWith the development of the textile and dye industry, a large amount of dye wastewater has been discharged. Semiconductor photocatalysis has been widely used in the treatment of environmental pollution, so it is very important to study efficient, nontoxic and stable photocatalysts.RESULTSIn this study, a microspherical activated carbon/Mn3O4/SrTiO3 composite photocatalyst with high catalytic activity was synthesized using sol–gel and chemical precipitation methods. The photocatalyst was characterized through X‐ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy, X‐ray photoelectron spectroscopy, photoluminescence, Electrochemical impedance spectroscopy, electron paramagnetic resonance spectroscopy and photocurrent measurements, and the effects of the initial methylene blue (MB) concentration and pH on the catalytic performance of the photocatalyst were investigated. The results revealed that the MC/Mn3O4/SrTiO3 composite has large light absorbance, and it can effectively inhibit photoinduced electron–hole pair recombination. The catalyst exhibited high photocatalytic degradation activity, and the degradation efficiency of MB at 300 ppm and pH 7 reached 99% after 80 min of UV light irradiation. The photodegradation process conformed to the pseudo‐first‐order kinetic model. Recyclability experiments showed that MC/Mn3O4/SrTiO3 composite has high stability, and the degradation rate of MB is > 70% after three repeat uses.CONCLUSIONSThis work provides a new method for finding low‐cost, high‐performance materials that can be modified and put into industrial use. © 2023 Society of Chemical Industry (SCI).

Phase-selective degree of hydration at setting: An in situ synchrotron diffraction study

Setting of Portland cements is still not well understood. Previous studies used techniques that analyse the pastes as a whole to correlate setting times with degree of hydration. Here, in-situ synchrotron X-ray diffraction analysed by the Rietveld method, with internal standard methodology, is used to derive alite dissolution rate and the crystallization kinetics of ettringite and portlandite in three commercial cements. Moreover, C–S–H gel precipitation pace has also been determined. C–S–H gel precipitation is key to account for setting. For grey Portland cements with w/c = 0.5, initial setting is attained when alite degree of hydration is close to 20% and the C−S−H gel content reached approximately 6 vol%.

Analysis of the epizootic situation of infectious anemia of horses in the Russian Federation for 2018– 2020

Relevance. The relevance of the topic is determined by the fact that an analysis of the epizootic situation of infectious anemia of horses in the Russian Federation has been carried out, with the identification of regions with a high degree of risk for this chronic infection. The dynamics of the spread of the disease in disadvantaged regions for the period 2018–2020 was analyzed.Methods. The main method of laboratory diagnosis of infectious anemia of horses is the study of blood serum in the diffuse precipitation in agar gel (AGID). For the analysis, we used the statistical data presented in the official reporting form 4-vet according to the Order of the Ministry of Agriculture of the Russian Federation dated 02.04.2008 No. 189 (“On the Regulations for the provision of information to the system of state information support in the field of agriculture”).Results. The article presents the results of the analysis of the prevalence of infectious anemia of horses in the country based on the results of serological studies in the AGID performed by the state veterinary laboratories of the constituent entities of the Russian Federation in 2018–2020. In total, 1,426,642 one-hoofed animals were examined in the Russian Federation for three years at EIAV, 1,322 horses positively responding to AGID were found (0.1%). The largest number of sick horses was found in the constituent entities of the Siberian and Ural Federal Districts. Horses infected with the EIAV virus were found in all 12 constituent entities of the Siberian Federal District, 640 animals (0.1% of those examined). A tense epizootic situation has developed in the Omsk, Novosibirsk, Irkutsk and Tomsk regions, the Altai Republic, and the Trans-Baikal Territory. In 5 constituent entities of the Ural Federal District, horses responding positively to EIAV were found, only 584 samples (0.3%), the largest number — in the Sverdlovsk and Tyumen regions. Isolated cases of horse disease EIAV were registered in the Amur Region, the Sakha Republic and the Primorsky Territory of the Far Eastern Federal District, as well as in other regions of the country. Thus, the epizootic situation according to EIAV on the territory of individual constituent entities of the Russian Federation remains tense, which indicates the need for constant monitoring of the spread of infection.

Effect of alkoxysilane on early age hydration in portland cement pastes

Silanes added during mortar or concrete preparation, may modify the fresh state properties, hydration kinetics and mechanical strength of the final product. The effects of silanes on cement hydration have been widely studied in the literature, however, there is some controversy about its effect at short ages. The present study was undertaken to determine the effect of a TEOS-based alkoxysilane (UCA-T), produced by ultrasound-assisted pre-hydrolysis of an oligomeric precursor, on early age cement paste hydration. The nature of the processes modifying the various stages of cement hydration kinetics in the presence of the alkoxysilane was ascertained by analysing paste composition at several ages (defined on the grounds of calorimetric curve results) using XRD, TG-DTG, FTIR and Raman spectroscopy. The calorimetric curve of pastes containing UCA-T exhibited a new early age, pre-induction period exothermal peak, indicative of UCA-T hydrolysis, C3A and C3S dissolution and ettringite and C–S–H gel precipitation. Portlandite, however, did not precipitate but reacts with the Si(OH)4 sourced from UCA-T hydrolysis to generate further C–S–H gel. The induction period following on that new exothermal peak was considerably longer than the period observed in the reference cement, an effect that intensified at higher UCA-T content.

Experimental and kinetic study of vacuum residue cracking over zirconium based catalysts

In this study, thermal cracking and catalytic cracking over zirconium-based catalysts of the vacuum residue were achieved in the presence of supercritical steam at 400–450 °C, 20 bar, and 2–4 h. Two different catalysts (ZrFeNi and ZrCoNi) were prepared using a sol–gel precipitation method and characterized using X-ray diffraction, EDX-spectrum, scanning electron microscopy, and BET surface area. The results showed the lowest VR conversion was achieved in the thermal cracking, catalytic cracking using ZrFeNi and catalytic cracking using ZrCoNi were 31.7, 35.3, and 38% while the highest VR conversion was achieved in the thermal cracking, catalytic cracking using ZrFeNi and catalytic cracking using ZrCoNi were 38.6, 71.1 and 76.3%. A new kinetic model of the eight lumps and 28 reaction steps were developed to describe the VR cracking while a genetic algorithm optimization method was used to predict the optimum set of kinetic parameters in which all computations were achieved using MATLAB version 2020a.

Production of hyperimmune serum against genotype VII Newcastle disease virus in rabbits with several applications.

Objective:This study aimed to produce hyperimmune serum against genotype VII Newcastle disease virus (NDV) with several applications.Materials and Methods:Production of hyperimmune serum against genotype VII NDV was performed on eight New Zealand white rabbits divided into four groups. Rabbits were immunized three times on the 1st day, the 14th day, and the 30th day. Blood sampling was carried out on the 8th day after the third immunization.Results:All groups showed the same pattern of hemagglutination inhibition (HI) titer results. HI titers would peak on the 5th or the 9th day after the second immunization, then decrease until the 3rd day after the third immunization, and increase again on the 5th day after the third immunization. Rabbits immunized intravenously showed higher HI titers than the other groups. These results indicate that the intravenous route for hyperimmune serum production against genotype VII Newcastle disease virus greatly affects the immune response result.Conclusions:The production of hyperimmune serum by intravenous immunization three times was able to produce the highest titer of 210 at 38 days. The agar gel precipitation test and the Western blot assay showed that the hyperimmune serum was specific for the Newcastle disease antigen.

Green biomaterial hydroxyapatite derived from waste marble powder for applications in water defluoridation: Comparative study on materials synthesized by different processing routes

This study presents different grades of hydroxyapatite (Hap) named as MA-Hap CM, MA-Hap USM and MA-Hap LR derived from marble powder a waste by-product of marble processing industry that serve as a good adsorbent for water defluoridation. These products have been compared with pure Hap for their method of synthesis, product characteristics (morphology, crystalline structure, size, shape, surface area), fluoride removal capacity and synthesis cost. Advanced process intensified technique such as ultrasonication had been incorporated into gel precipitation conventional technique in order to produce high quality pure nano Hap, with higher yield, lesser synthesis time and of higher fluoride adsorption capacity. Energy efficiency and synthesis cost comparison studies proved MA-Hap a potential adsorbent for drinking water application.

Synthesis of synthetic amorphous silica powder from palm oil mill fly ash extract by carbon dioxide impregnation

Palm oil mill fly ash (POMFA) is rich in amorphous silica and can be extracted by sodium hydroxide solvent. This work aims to synthesize synthetic amorphous (SAS) powder silica that has mesoporous pores and a high specific surface area. The sol–gel precipitation process was applied by CO 2 impregnation and polyethylene glycol (PEG) 400 was used as the surfactant to obtain the synthetic silica powder from the extract. A temperature-controlled 1000 cm 3 glass precipitator equipped with a stirrer was used for the precipitation process. The extracted silica was mixed with PEG at pre-determine concentration, and 500 cm 3 of the mixed liquid was put in the precipitator and stirred at 1000 RPM. The carbon dioxide impregnated at a flow rate of 100 cm 3 min −1 to destabilize the silica extract. The study was done by using PEG-400 as a dispersant to improve the specific surface area of the obtained precipitated silica. The temperature, precipitation time, and the PEG concentration were varied to study their effect on SAS yield. The optimum SAS yield of 80.01% was obtained at a temperature of 70 °C, time of 90 min, and a PEG concentration of 5%. The characteristics of the SAS obtained are SSA of 198.55 m 2 g −1 , volume pore of 0.289 cm 3 g −1 , and pore diameter of 5.32 nm.

Development of SarS-Cov-2 antigen Detection Kit Based on Immunoglobulin Y (Igy) Using Surface Plasmon resonance (SPr)

SARS disease reappeared at the end of 2019 with a new name as Coronavirus Disease 2019 (COVID-19) caused by a new virus called SARS-CoV-2. This virus has spread throughout the world until recently and caused massive deaths and losses. The nucleic acid test in the form of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) is very important to diagnose COVID-19 in patients, but this method has several drawbacks such as operators who have to be trained, the diagnosis results appear in a relatively long time, and the examination price relatively expensive. This research was conducted to produce immunoglobulin Y (IgY) extracted from chicken egg yolk targeting the S-protein receptor-binding domain (RBD) on SARS-CoV-2 as a component of the surface plasmon resonance (SPR) SARS-CoV-2 antigen detection kit. This research was started by extracting IgY from hyperimmune chicken egg yolks with the polyethylene glycol (PEG) precipitation method and continued with dialysis. The extracted IgY was further purified using thiophilic adsorption chromatography and concentrated by using Amicon® Ultra-15 ultrafiltration. The IgY activity against SARS-CoV-2 RBD was tested qualitatively using the agar gel precipitation test (AGPT) technique and the total protein content was determined using the Lowry method. IgY was tested for its affinity against SARS-CoV-2 RBD using SPR. The IgY concentration obtained was 11 mg/mL. The AGPT result showed the presence of IgY activity against SARS-CoV-2 RBD isolated from egg yolk and chicken serum after 8 weeks after the first vaccination of chickens. The SDS-PAGE results showed a very clear band of IgY characters. The obtained IgY showed adequate interaction with commercial SARS-CoV-2 RBD on an SPR device. The purified IgY was able to bind with protein-S RBD and showed a fairly good affinity for the SARS-CoV-2 antigen sample. The results of these observations indicate that IgY anti-S-protein SARS-CoV-2 can be produced and purified from chicken egg yolk and can be used as a diagnostic component to detect SARS-CoV-2 antigen, especially on SPR.

A Case Series of Diphtheria in Western India: Time to Revisit Vaccination Coverage and Policy?

INTRODUCTION: Diphtheria is a significant child health problem in countries with low immunization coverage. Reports of diphtheria in the adult population are also increasing. Here we describe case series of diphtheria in western India for 6 months. OBJECTIVE: To identify and isolate Corynebacterium species, demonstrate the isolates for toxigenicity and examine the immune status of the patients by estimating antibody titers in sera (anti-diphtheria toxoid IgG). METHODS: Twelve patients admitted with clinical suspicion of oropharyngeal diphtheria for six months. In each case, two throat swabs were collected and primary identification of Corynebacterium diphtheriae was done by direct microscopy (Gram's and Albert's stains), bacteriological culture and biochemical tests as per the standard procedure. Culture isolates were tested for toxigenicity by Elek's gel precipitation and were sent to a reference laboratory for tox A gene detection by polymerase chain reaction. Anti-diphtheria toxoid IgG antibody levels were determined in patient’s sera using a commercial Anti-Diphtheria Toxoid IgG Enzyme-Linked Immunosorbent Assay (EUROIMMUN, Germany) at a reference laboratory. RESULTS: All 12 patients presented with oropharyngeal diphtheria with the formation of pseudomembrane in the oropharynx. Eleven patients were of the pediatric age group and one was an adult. The microbiological diagnosis was achieved for 11 patients and one was diagnosed clinically. Based on vaccination history, microbiological findings and distribution of anti-diphtheria toxoid IgG antibodies titers, the results showed persistence of toxigenic strain of Corynebacterium diphtheriae circulating in our region. CONCLUSIONS: The present study demonstrated that toxigenic strains of C. diphtheriae are circulating in this geographical location which indicates the need for constant epidemiological surveillance ensuring early detection of diphtheria and review the efficacy of the immunization programme.

Proposal of a subtype of serovar 4, K4b:O3, of Actinobacillus pleuropneumoniae based on serological and genotypic analysis

The aim of this study was to investigate an isolate of Actinobacillus pleuropneumoniae, named 14–760, which was serologically not classifiable among the recognised serovars of A. pleuropneumoniae. It reacted with the antisera raised against serovars 3, 6, 8, 15 and 17 in the agar gel precipitation (AGP) test, and was positive in the capsular serovar 4-specific PCR (cps4B PCR) assay. The isolate contains a type II capsule locus similar to serovar 4 but with variations in the length of four intergeneric regions (modF-cpxA, cpxD-cpsA, cpsC-a 114 bp orf, and lysA-ydeN), and three gene sequences (modF, cpsC and ydeN). The main difference found between the K4 and K4b cps genes is the additional 35 AAs found in type 4b due to a 4 bp insert in cps4bC. The LPS O-Ag locus is highly similar to that of reference strains of serovars 3, 6, 8, 15, 17 and 19. Isolate 14–760 is biovar 1 and contains solely the structural genes required for toxin ApxII production (apxIICA), and the type I secretion system (apxIBD) for the export of ApxII. Antiserum against isolate 14–760 adsorbed with antigen prepared from serovars 8, 15 or 17 reference strains remained reactive with isolate 14–760, but not with antigens prepared from serovars 1–18. Taken together, our results indicate the existence of a subtype of A. pleuropneumoniae, serovar 4, that we called “K4b:O3″, and we propose isolate 14–760 as the reference strain.