Filter Discs Research Articles

Adaptor protein 14-3-3zeta promotes corneal wound healing via regulating cell homeostasis, a potential novel therapy for corneal injury

Severe corneal injury can lead to blindness even after prompt treatment. 14-3-3zeta, a member of an adaptor protein family, contributes to tissue repair by enhancing cellular viability and inhibiting fibrosis and inflammation in renal disease or arthritis. However, its role in corneal regeneration is less studied. In this study, filter disc of 2-mm diameter soaked in sodium hydroxide with a concentration of 0.5 N was placed at the center of the cornea for 30 s to establish a mouse model of corneal alkali injury. We found that 14-3-3zeta, which is mainly expressed in the epithelial layer, was upregulated following injury. Overexpression of 14-3-3zeta in ocular tissues via adeno-associated virus-mediated subconjunctival delivery promoted corneal wound healing, showing improved corneal structure and transparency. In vitro studies on human corneal epithelial cells showed that 14-3-3zeta was critical for cell proliferation and migration. mRNA-sequencing in conjunction with KEGG analysis and validation experiments revealed that 14-3-3zeta regulated the mRNA levels of ITGB1, PIK3R1, FGF5, PRKAA1 and the phosphorylation level of Akt, suggesting the involvement of the PI3K-Akt pathway in 14-3-3zeta-mediated tissue repair. 14-3-3zeta is a potential novel therapeutic candidate for treating severe corneal injury.

Electrochemical flow-through biosensors based on microfiber enzymatic filter discs placed at printed electrodes

A new type of electrochemical biosensors in a flow injection system with printed electrodes were developed and tested. A filter disc (7 mm diameter) with immobilized enzyme was placed at the printed electrode. This conception combines the advantages of biosensors with a bioreceptor at the electrode surface and systems with spatially separated enzymatic and detection parts. Filters of different composition (glass, quartz, and cellulose), thickness, porosity, and ways of binding enzyme to their surface were tested. Only covalent bonds throughout a filter-aminosilane-glutaraldehyde-enzyme chain ensured a long-time and reproducible biosensor response. The developed method of biosensor preparation has been successfully applied to enzymes glucose oxidase, laccase and choline oxidase. The dependences of peak current on detection potential, flow rate, injection volume, analyte concentration as well as biosensor lifetime and reproducibility were investigated for glucose oxidase biosensor. The sensitivity of measurements was two or more times higher than that of biosensor with a mini-reactor filled by powder with immobilized enzyme. The developed biosensor with laccase was tested by determining dopamine in the pharmaceutical infusion product Tensamin®. Results of the analysis (40.0 ± 0.7 mg mL−1, SD = 0.8 mg mL−1, RSD = 1.85 %, N = 11) show a good agreement with the manufacturer's declared value.

Shape optimization using the adjoint solver in computational fluid dynamics for additive manufacturing of a pollen filter

Pollen filters play an essential role in protecting people from airborne allergens and ensuring indoor air quality. Allergic reactions to pollen can lead to discomfort, reduced productivity, and increased healthcare costs. A low pressure drop of these pollen filters not only enhances the comfort of individuals using the filters but also contributes to energy savings in ventilation systems, thereby promoting environmental sustainability. This research focuses on the shape optimization of pollen filters using the adjoint solver in computational fluid dynamics, aiming to enhance both human health and environmental sustainability. In a previous study, an approach using the adjoint solver was developed to optimize both the separation efficiency and the pressure drop. In the current work, a methodology is presented that exploits these findings and allows the design of initial structures, subsequent optimization, and detailed experimental and numerical comparisons with a reference filter using the example of a pollen filter. To validate the effectiveness of the optimized filter, the initial geometry and the optimized geometry were fabricated and tested on a test bench. Compared to a reference filter, our filter disk was able to separate 2.9% more particles of size 6 μm and the pressure drop was lower by 34.2%. This research work demonstrates that the developed method can effectively be used to improve the performance of pollen filters. The results obtained from the validation suggest that the optimized geometry of the filter exhibits higher separation efficiency while keeping the pressure drop low compared to state-of-the-art pollen filters.

Based on Fluent, the numerical simulation of the flow field on the filter disk surface of the rotary filter device

The rotary screen filter is the most typical basic structural element in rotating mechanical devices. It is being widely applied in various fields of industrial production. Using a spinning disc as the research subject, this study utilizes Computational Fluid Dynamics (CFD) techniques to establish a physical model of the filter disc. Various parameters and their corresponding boundary conditions are set, followed by a comprehensive and detailed three-dimensional numerical simulation of the high-speed rotating disc using the Fluent software platform. The objective is to investigate the effects of disc rotation speed and liquid inlet velocity on the surface flow field, as well as the influence of rotational speed on the attachment of particle impurities to the surface. Finally, the computational results will be visualized and thoroughly analyzed.

FINDeM: A CRISPR‐based, molecular method for rapid, inexpensive and field‐deployable organism detection

Abstract The field of ecology has undergone a molecular revolution, with researchers increasingly relying on DNA‐based methods for organism detection. Unfortunately, these techniques often require expensive equipment, dedicated laboratory spaces and specialized training in molecular and computational techniques; limitations that may exclude field researchers, underfunded programmes and citizen scientists from contributing to cutting‐edge science. It is for these reasons that we have designed a simplified, inexpensive method for field‐based molecular organism detection—FINDeM (Field‐deployable Isothermal Nucleotide‐based Detection Method). In this approach, DNA is extracted using chemical cell lysis and a cellulose filter disc, followed by two body‐heat inducible reactions—recombinase polymerase amplification and a CRISPR‐Cas12a fluorescent reporter assay—to amplify and detect target DNA, respectively. Here, we introduce and validate FINDeM in detecting Batrachochytrium dendrobatidis, the causative agent of amphibian chytridiomycosis, and show that this approach can identify single‐digit DNA copies from epidermal swabs in under 1 h using low‐cost supplies and field‐friendly equipment. This research signifies a breakthrough in ecology, as we demonstrate a field‐deployable platform that requires only basic supplies (i.e. micropipettes, plastic consumables and a UV flashlight), inexpensive reagents (~$1.29 USD/sample) and emanated body heat for highly sensitive, DNA‐based organism detection. By presenting FINDeM in an ecological system with pressing, global biodiversity implications, we aim to not only highlight how CRISPR‐based applications promise to revolutionize organism detection but also how the continued development of such techniques will allow for additional, more diversely trained researchers to answer the most pressing questions in ecology.

Nanosized quantum dots-wrapped metallic particles ensembles integrated into filter disc-based analytical device for garlic evaluation. Application to monitor fake pickled garlic in balsamic vinegar

Herein, an affordable and simple analytical device is presented to portable identify of garlic in 30 min; the evaluation needs no pre-treatment of sample. The analytical device fabrication was did employing a headspace-based nanosensor array using of inexpensive materials as commercial filter discs, quantum dots (QDs), and metallic nanoparticles (MNPs). The nanoarray is fabricated by the accumulation QDs on MNPs surface, that results in the production of ensembles of QDs/MNPs. The ensembles generate diverse colorimetric profiles as “fingerprints” regarding to each garlic sample. The volatile organosulfur compounds (OSCs) of garlic can prefer binding to the MNPs comparing with QDs. The color profiles can be displayed with a smartphone camera, which can be quantitatively distinguished by chemometrics approaches. The analytical device was used to assessment of fake pickled samples in balsamic vinegar. This device proves well potential for qualitative control of garlic.

The effect of sawdust on the pore structure and properties of low-cost ceramic water filter materials

Low-cost ceramic water filters are a very effective point-of-use technology for removing bacteria and protozoa from drinking water. The filters are made from locally sourced clay and a porogen materials such as sawdust. It is recommended that the sawdust be sieved to 30-sieve (600 μm) to make reliable filters. However, the size distribution of sawdust is usually broad and can extend below 100 μm. This study divided 30-sieve sawdust into four narrower size distributions and made filter disks for measurement of hydraulic conductivity and bulk density. Additionally, the microstructure of the materials was examined in three dimensions by micro-CT. The results showed that, independent of sawdust particle size, the void volume fraction in the filter increased linearly with the weight fraction of sawdust. In contrast, the permeability coefficient increased non-linearly as the fraction of sawdust increased. The magnitude of the permeability was higher for the larger sawdust particles when the sawdust fraction was 10 wt% or higher. Three-dimensional imaging of the pore structure in the filters suggested that the non-linear increase in permeability with increasing weight fraction of sawdust may be associated with increased interaction of the cavities created by the sawdust.

SlGSTE8 in Spodoptera litura participated in the resistance to phoxim and chlorpyrifos

AbstractGlutathione S‐transferases (GSTs) were reported to participate in insecticide resistance by metabolic and antioxidant activities. In our previous study, an ε class gene of GSTs, SlGSTe8 in Spodoptera litura, was screened out to be upregulated in a population resistant to pyrethroids and organophosphates. SlGSTe8 was highly expressed in the larvae stage, and the digestive tissue, foregut, midgut and hindgut, while the relative expression level was low in the pupae stage and other tissues. To further explore its role in the resistance to pyrethroids and organophosphates, the metabolic activity to insecticides by its recombinant protein was determined by Ultra Performance Liquid Chromatography, and its antioxidant enzyme activity was evaluated by disc diffusion assay. The recombinant protein showed significant metabolic activity to phoxim and chlorpyrifos, but not to fenvalerate, cyhalothrin or β‐cypermethrin. After incubation, the depletion rate of chlorpyrifos is 85.3%, higher than that of phoxim (17.5%). Also, the inhibition zone around filter discs decreased significantly after exposure to cumene hydroperoxide in recombinant plasmid than vector only, suggesting significant antioxidant activity of SlGSTE8. Further modelling and docking analysis indicated that the 3D structure of SlGSTE8 was well shaped for phoxim and chlorpyrifos, with the binding energy −5.58 and −5.15 kcal/mol, respectively. Our work provides evidence that SlGSTe8 in S. litura plays important roles in phoxim and chlorpyrifos resistance.

Electrospun Poly (Vinylidene Fluoride-Co-Hexafluoropropylene) Nanofiber Membranes for Brine Treatment via Membrane Distillation.

The major challenge for membrane distillation (MD) is the membrane wetting resistance induced by pollutants in the feed solution. The proposed solution for this issue was to fabricate membranes with hydrophobic properties. Hydrophobic electrospun poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber membranes were produced for brine treatment using the direct-contact membrane distillation (DCMD) technique. These nanofiber membranes were prepared from three different polymeric solution compositions to study the effect of solvent composition on the electrospinning process. Furthermore, the effect of the polymer concentration was investigated by preparing polymeric solutions with three different polymer percentages: 6, 8, and 10%. All of the nanofiber membranes obtained from electrospinning were post-treated at varying temperatures. The effects of thickness, porosity, pore size, and liquid entry pressure (LEP) were studied. The hydrophobicity was determined using contact angle measurements, which were investigated using optical contact angle goniometry. The crystallinity and thermal properties were studied using DSC and XRD, while the functional groups were studied using FTIR. The morphological study was performed with AMF and described the roughness of nanofiber membranes. Finally, all of the nanofiber membranes had enough of a hydrophobic nature to be used in DCMD. A PVDF membrane filter disc and all nanofiber membranes were applied in DCMD to treat brine water. The resulting water flux and permeate water quality were compared, and it was discovered that all of the produced nanofiber membranes showed good behavior with varying water flux, but the salt rejection was greater than 90%. A membrane prepared from DMF/acetone 5-5 with 10% PVDF-HFP provided the perfect performance, with an average water flux of 44 kg.m-2.h-1 and salt rejection of 99.8%.

Developing Cost-Effective and Efficient Drinking Water Treatment Technology for the Removal of Salinity and Suspended Solids

Although a variety of economical water treatment options are available, rural residents struggle to have safe drinking water. Therefore, developing cost-effective and efficient drinking water treatment technology for the removal of selected ionic compounds and suspended solids is necessary. The present study aims to establish a cost-effective water treatment method by employing the following adsorbents Graphene Sand Composite (GSC), GSC with Moringa Oleifera seeds, Phyllanthus emblica seeds, Strychnos potatorum seeds, tea waste, sawdust, coal, coconut charcoal, and clay pot (an indigenized filter). X-ray diffraction of GSC confirms SiO2 nanoparticles, a broad peak centred at 22.5°, Graphene peaks are found at 26.73 (200), 45.8 (110) and 54.959 (222). In FT-IR, graphene oxide has a strong and wide O-H/ Si-OH stretching vibration peak at 3444 cm-1. In the Raman spectrum, the graphitic vibration band from its first-order scattering of E2g photons using sp2 carbon appeared at 1589 cm-1. Moreover, the graphitic vibration band contributes to the presence of stretching C-C bond; which is common in all sp2 carbon systems. Water’s pH, TDS, hardness, and chloride content also increased considerably in a few adsorbents. Fabricated pots with an indigenous filter using GSC and Moringa oleifera seed as filter disc has also been designed and evaluated in the present study. In this research, 100% salinity removal is achieved using GSC as an adsorbent. While there is an interesting rise trend in fluoride and calcium content to 33% and 39%, respectively. The reason for the rise in fluoride and calcium can be studied further.

A systematic investigation of the relationship between properties of bulk foam and foam in porous media

Bulk foam analysis (static test) is simple and fast, which makes it a cost-effective method for screening and ranking hundreds of surfactants being considered for foam applications. Coreflood tests (dynamic test) can also be used, but it is quite laborious and costly. However, previous reports show that ranking based on static tests sometimes differs from ranking based on dynamic tests. To date, the reason for such a discrepancy is not well understood. Some believe that it may be due to faulty experimental design while some others believe that there is no discrepancy if the right foam performance indices are used to describe and compare the results from both methods. For the first time, this study reports a systematic series of static tests conducted on different foaming solutions (with surfactant concentration ranging from 0.025 to 5 wt%) and duplicated in dynamic tests using the same core sample for all the surfactant solutions. The dynamic test was also repeated on three different rocks of a wide permeability range (26–5000 mD) for each of the surfactant solutions. Unlike previous studies, here multiple dynamic foam indices (limiting capillary pressure, apparent viscosity, trapped foam, and trapped to mobile foam ratio) were measured and compared with the performance indices measured from the static tests (foam texture and foam half-life). Dynamic tests were in total agreement with static tests for all the foam formulations. However, it was observed that the pore size of the base filter disk used in the static foam analyzer can be a potential source of conflicting results when comparing with dynamic test. This is because a threshold pore size exists above which some foam properties (apparent viscosity and trapped foam) significantly decreased compared to the properties before that threshold. Foam limiting capillary pressure is the only foam property that does not show such a trend. It also appears that such threshold occurs above a certain surfactant concentration (0.025 wt%). Apparently, it becomes imperative that the pore size of the filter disk used in the static test and the porous medium used in dynamic tests must be on the same side of the threshold point, otherwise there may be disparity in their results. The threshold surfactant concentration should also be determined. The role of these two factors (pore size and surfactant concentration) requires further investigation.

One-Stop Extraction and In Situ RT-qPCR for Ultrasensitive Detection of Highly Diluted SARS-CoV-2 in Large-Volume Samples from Aquatic Environments.

Surveillance of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in aquatic environments attracted attention due to its considerable impacts on human health and ecology, especially in countries with poor sanitation standards. Based on a strategy of one-stop extraction and in situ amplification, we developed an ultrasensitive method that uses a polyacrylamide derivative-modified filter disc (PAD-FD), in which highly diluted RNA can be efficiently concentrated onto the filter disc and directly used for amplification. A newly designed spin column with a cup-like filter base facilitated the non-contact transfer of the affinity filter disc from the column to a PCR tube. The limit of detection of the PAD-FD coupled with RT-qPCR is 10 copies/mL. Using 32 suspected SARS-CoV-2 samples, we demonstrated that the detection rate of our method (62.5%, 20/32) was triple the rate of the commercial kit (18.8%, 6/32). Using a PAD-FD, 56.3% (18/32) and 40.6% (13/32) of the 10-fold-dilution samples with river and tap water, respectively, were detected. Even when diluted 100-fold, 28.1% (9/32) and 37.5% (12/32) were still detected in river and tap water, respectively. We believe that the PAD-FD method offers an accurate testing tool for monitoring viral RNA in aquatic environments, contributing to the forewarning of the SARS-CoV-2 outbreak and the breaking of the transmission chain.

Norway spruce somatic embryogenesis benefits from proliferation of embryogenic tissues on filter discs and cold storage of cotyledonary embryos.

Vegetative propagation opens opportunities for the multiplication of elite tree progeny for forest regeneration material. For conifers such as Norway spruce (Picea abies) the most efficient vegetative propagation method is seed multiplication through somatic embryogenesis. Efficient culture methods are needed for somatic embryogenesis to be commercially viable. Compared to culturing as clumps, filter disc cultures can improve the proliferation of embryogenic tissue (ET) due to more even spread and better developmental synchronization. In this study, ET proliferation on filter discs was compared to proliferation as clumps. The study comprised 28 genotypes in four trials. The benefits of adding a pre-maturation step and the selection of fresh ET for the subculture were evaluated. Pre-maturation on hormone-free media before maturation did not significantly improve embryo yield but improved greenhouse survival from 69% to 80%, although there was high variation between lines. Filter disc cultivation of ET did result in better growth than in clumps but was more dependent on ET selection and the amount of ET than the clump cultivation method. Filter proliferation also favors certain lines. Post-maturation storage can be used to change the storage compound composition of the produced mature embryos. The embryo storage compound profile was analyzed after post-maturation cold storage treatments of 0, 4, 8, 31, and 61 weeks and compared to that of the zygotic embryos. Cold storage made the storage compound profile of somatic embryos closer to that of zygotic embryos, especially regarding the raffinose family oligosaccharides and storage proteins. Sucrose, hexose, and starch content remained higher in somatic embryos even through cold storage. Prolonged storage appeared less beneficial for embryos, some of which then seemed to spontaneously enter the germination process.

Purification of crosslinked, highly viscous and viscoelastic hyaluronic acid hydrogels by dynamic diafiltration

The current study shows a new possibility to purify crosslinked hydrogels based on hyaluronic acid (HA) to remove the residual crosslinking agent 1,4 - butanediol diglycidyl ether (BDDE) and its byproduct 1,4-butanediol di-(propan-2,3-diolyl) ether (EPD) using a crossflow filtration (CFF) device. Therefore, a dynamic crossflow-filtration (DCF) device with rotating and semipermeable ceramic filter discs (5 nm, 60 nm, 2000 nm) was used. No negative impacts on the thermal stability and rheological characteristics of the biopolymer could be shown. Furthermore, it was discovered, that 7 diafiltration volumes (DV) are sufficient to reduce the residual contaminants to < 0.1 % from the initial concentration and that the hyaluronic acid (HA) rejection coefficient (R) is 0.99 regardless of the chosen membrane pore size, while the permeability of BDDE and EPD remains at almost 100 %. No correlation between the membrane pore size and the flux could be found. For all membranes, the flux is surprisingly dropping after 0.5 DV was processed, which could be linked to the HA swelling and membrane pore blocking effects. The highest flux was determined for the 60 nm membrane with 32 Lm-2h−1 at steady state. The stability of the biopolymer is neither negatively influenced by the applied shear forces due to the rotational membrane velocity, nor by the applied thermal stress conditions for 6 months at 25 °C, 60 % relative humidity (r.h.) and 40 °C, 75 % r.h. The presented results show that a dynamic diafiltration can be regarded as a promising alternative to conventional purification methods.

Performance evaluation of nanosilica derived from agro-waste as lost circulation agent in water-based mud

Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation. The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks. Loss circulation materials (LCMs) are commonly introduced into the drilling mud to prevent or minimize filtrate loss. This study investigates silica nanoparticle (SNP) derived from rice husk (RH) termed RH-SNP using the wet-milling method as an LCM in water-based mud (WBM). The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied. Subsequently, the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk. The performance of the developed RH-SNP was compared with the widely applied nutshell. The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%, respectively, and minimized the fluid loss of the WBM by 47% at 80 °F. The enhancement is due to the particles ability to spread and interact efficiently with the WBM. With the use of 1 mm and 2 mm simulated fracture for 7 min, the mud loss volume of the base mud reduced by 50%, 66.7%, 86%, and 90% (for 1 mm) and 40%, 65.7%, 77.1%, and 80% (for 2 mm) with the inclusion of 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt% of RH-SNP, respectively. Overall, the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell. The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.

Bacterial invasion into the epidermis of rats with sodium lauryl sulphate-irritated skin increases damage and induces incontinence-associated dermatitis.

Incontinence-associated dermatitis (IAD) is caused by prolonged exposure to urine/liquid stool. It is a common and often painful skin condition in older incontinent adults because of poor prevention. Patients with urinary infections are at risk of developing IAD, and to guide the development of novel prevention strategies, we aimed to develop an animal model of IAD by urine and bacteria. First, contralateral sites on the dorsal skin of Sprague-Dawley rats were compromised by sodium lauryl sulphate (SLS), simulating frequent cleansing with soap/water. Filter discs were then placed inside ring-shaped chambers on foam dressings, inoculated with or without Pseudomonas aeruginosa, covered with agarose gels immersed in cultured filtrated urine, and secured in place with an occlusive dressing for 3 days. Untreated and SLS-compromised sites served as controls. The IAD was developed at bacteria-inoculated sites, characterised by severe IAD-like redness that persisted for up to 3 days post-exposure and higher disruption of the skin barrier function compared with non-inoculated sites. Pathological changes included epidermal thickening, partial skin loss, inflammatory cell infiltration, accumulation of red blood cells, and invasion of bacteria into the epidermis. This novel, clinically relevant IAD rat model can serve for future prevention developments.

AN ASSESSMENT OF PHYSICOCHEMICAL AND MICROBIOLOGICAL CHARACTERISTICS OF WATER IN INSUKAMINI CATCHMENT WATER SOURCES AND THE SUITABILITY OF WATER FOR DOMESTIC USE

Insukamini catchment depends on hand dug wells, sand water abstraction, dam, and borehole water sources for their domestic uses. On hand dug wells and sand water abstraction, people rely on natural filtration of bacteria and consider the water as safe, however the location and management of some of these water sources raise suspicion of possible contamination. The aim of this study was to assess drinking water quality in terms of selected physico-chemical and microbiological parameters, and people's perceptions on aesthetic parameters. Water samples were collected from five water sources, namely sand water abstraction, dam, hand dug well, borehole and municipal water. Three samples were collected from each water source to make 63 samples. Temperature, pH, electrical conductivity, and dissolved oxygen measured using HI 9143 dissolved oxygen meter, YSI pH 100, HI 9143 dissolved oxygen meter and HI 8633 conductivity meter respectively. On laboratory experiments total suspended solids measured using filter disk, total dissolved solids using gravimetric method (SA, 2008), total and feacal coliform were measured using spread plate method. All water sources had total coliform levels above the WHO standards for drinking water of 1000mg/L. For E. coli, borehole and municipal water sources complied with the WHO standard with the means of zero cfu/ 100ml. Low pH mean of 5.001 was found in borehole water and the other water sources were within the accepted range of 6.5 to 8.5. Municipal and dam point (A) water sources had highest levels of TDS, borehole, and dam point (C) had TSS levels above maximums allowable of 1000mg/L and 150mg/L respectively. Temperature, DO and EC of all water sources were within the WHO standards. Overall, all water sources were not complying with WHO standard for drinking water. People described municipal water source as best for drinking purpose, dam, sand water abstraction and hand dug well water sources described as soft and good for laundry and bathing as compared to borehole which was described as hard. The results indicated that water from the sources under study were not suitable for drinking purposes without treatment. The water should rather be used for other domestic uses such as laundry and bathing. However, municipal water should be boiled or use water purification tablets (chlorine tablets) before drinking. An integrated approach is therefore required to minimize and avoid water pollution within the catchment.

Light absorptance of algal films for photosynthetic rate determinations

A Reflectance Absorptance Transmittance (RAT) meter, developed for routine measurements of Abtλ nm on leaves, was used to measure absorptance of algal films mounted on glass fibre filter disks for use in PAM (Pulse Amplitude Modulation) fluorometry. Absorptance readings (Abtλ nm) are essential to quantitate the photosynthetic electron transport rate from PAM data and are also helpful if algal disks are used in an IRGA (InfraRed Gas Analyzer). Measurements were made on Synechococcus R-2 (Cyanophyceae), Acaryochloris marina (Chlorobacteria), Chlorella vulgaris (Chlorophyceae), Chaetoceros sp. (Bacillariophyceae) and Isochrysis sp. (Haptophyta) in blue (445 nm), green (525 nm) and red (625 nm) light. Plots of Abtλ vs. Chl a (mg Chl a m-2) or Chl d for Acaryochloris (mg Chl d m-2) of the algae followed exponential saturation curves (Abt%λ = Abt%λ, ∞ (1-e-k×Chl)) usually reaching asymptotes in the blue light used by blue-diode PAM machines. Synechococcus, Chlorella, Chaetoceros and Isochrysis Abt%445nm saturates ≈ 50-100 mg Chl a m-2 (Synechococcus: Abt%445 nm, max = 77.3±0.94, ±95% conf. limits, Chlorella: Abt%445 nm, max = 77.0±2.06, Chaetoceros: Abt%445 nm, max = 80.6±1.87; Isochrysis: 83.2±8.06 mg Chl a m-2); Acaryochloris above about 100 mg Chl d m-2. Asymptotic loading of cells was in general easily achieved in blue light in the case of Synechococcus, Chlorella and Acaryochloris but not in green, red or “white” light. It was difficult to achieve asymptotic loading for Chaetoceros and Isochrysis due to mucilaginous blockage of the filter disks.

Microbial evaluation of some syrups in Syrian pharmacies

Microbial contamination of syrups can bring clinical hazards to patients as well as physical and chemical changes in the product. AimsStudying the influence of the war on the Syrian pharmaceutical industry from a microbiological point of view by assessing the microbiological quality of syrup samples taken from Syrian pharmacies. MethodologyFifty different syrups from 29 different companies having various manufacture dates were collected during validity period between 9-2019 and 6-2021 in Aleppo, Syria. Membrane filtration technique was performed to quantify microbial contamination of the collected syrup samples. This involved passing the samples through filter nitrocellulose membrane disks with a pore size of 0.45 μm then transferring the filter disks alongside any collected microorganisms into Tryptone Soya Agar, Sabouraud Dextrose agar, Xylose lysine Deoxycholate agar and Eosin Methylene Blue agar plates. Colonies observed on these plates were counted and the number of viable microbes in the original sample was expressed as colony forming units per milliliter (CFU/mL). Investigation of Escherichia coli in all syrup samples and Salmonella in herbal syrup samples was also performed. ResultsThis study revealed that 28 syrups (56%) had no growth of either bacterial or fungal colonies; 33 syrups (66%) had no growth of bacterial colonies; 43 syrups (86%) had no growth of fungal colonies. On the other hand, 7 syrups (14%) exceeded the pharmacopoeial limit for bacterial growth and 6 syrups (12%) exceeded that for fungal growth. Furthermore, 5 syrup samples (10%) were on the high permissible limits for bacterial contamination and none for fungal contamination.All syrups were free from E. coli and all herbal syrups were free from Salmonella. Taken together, out of the fifty syrups examined 13 syrups (26%) exceeded the pharmacopoeial limits and therefore pharmacopoeial accepted syrups constitute a percentage of (74%). ConclusionAlthough the majority of samples tested showed compliance with the pharmacopoeial limits of microbiological contamination, the small proportion of syrups in the Syrian market exceeding the pharmacopoeial limit is still concerning and reveals the implications of post-war conditions on the quality of manufacturing in the Syrian pharmaceutical industry. That said, it remained within the proper limits compared to studies conducted in other countries in similar situations.This study, therefore, highlights the need to apply the Good Manufacturing Practice (GMP) rules more strictly in order to limit microbiological contamination in pharmaceutical syrups to ensure the quality of products and safety of users. We suggest that further quality control studies are conducted on a larger scale and repeated more frequently.

Biological Assessments of Baccharis dracunculifolia DC from a Cerrado fragment in Central-West Brazil

Baccharis dracunculifolia is used as an herbal medicine, and green propolis, synthesized by Apis mellifera bees from it, has inflammatory, antioxidant and antimicrobial principles. This bee product is effective in combating a series of microorganisms in folk medicine, so it is essential to develop research to prove this effectiveness. The objectives of the work were to analyze the microbiological profile, dose the flavonoids and verify the plant's antioxidant activity. The aerial parts were collected in a fragment of cerrado sul-mato-grossense and processed, obtaining extracts with hexane, ethyl acetate and ethanol. For microbiological analysis, Staphylococcus aureus bacteria was seeded in agar and filter discs were soaked with the extracts and, together with the control group, were placed in Petri dishes for subsequent measurement of inhibition halos. To measure the flavonoids and evaluate the antioxidant activity, processed leaves were taken to Soxhlet for extraction in methanol. An aliquot was read in a spectrophotometer with different concentrations of quercetin to build a standard curve. The antioxidant assay was based on the radical reduction and development method using DPPH. As a result, all extracts showed inhibition of bacterial growth, indicating antimicrobial activity of the plant. Flavonoids with satisfactory antioxidant activity were also found. Taking into account that B. dracunculifolia is used as a medicinal plant, studies such as this one can corroborate with such use, since the scientific proof of possible herbal medicines is essential for the pharmaceutical industry and for health professionals, contributing to the evolution of medicine.