Total Optical Density Research Articles

High levels of anti–factor VIII immunoglobulin G4 and immunoglobulin G total are associated with immune tolerance induction failure in people with congenital hemophilia A and high-responding inhibitors

BackgroundImmune tolerance induction (ITI) is the treatment of choice to eradicate neutralizing anti–factor (F)VIII alloantibodies (inhibitors) in people with inherited hemophilia A. However, it is not successful in 10% to 40% of the cases. The biological mechanisms and biomarkers associated with ITI outcome are largely unknown. ObjectivesThe aim of this study was to investigate the association of plasma cytokines (interferon-γ, tumor necrosis factor, interleukin [IL]-2, IL-4, IL-5, IL-6, IL-10, and IL-17A), chemokines (IL-8/CXCL8, RANTES/CCL5, MIG/CXCL9, MCP-1/CCL2, and IP-10/CXCL10), and anti-FVIII immunoglobulin (Ig) G total, IgG1, and IgG4 with ITI outcome. MethodsIn this cross-sectional analysis of the Brazilian Immune Tolerance Study, we assessed plasma levels of anti-FVIII IgGs using an enzyme-linked immunosorbent assay with plasma-derived FVIII and recombinant FVIII as target antigens, immobilized in microplates. ResultsWe assayed 98 plasma samples of moderately severe and severe (FVIII activity, <2%) people with hemophilia A after completion of a first ITI course. Levels of anti–recombinant FVIII IgG total and IgG4 were higher in people with hemophilia A who failed ITI (IgG total optical density [OD], 0.37; IQR, 0.15-0.73; IgG4 OD, 2.19; IQR, 0.80-2.52) than in those who had partial (IgG total OD, 0.03; IQR, 0.00-0.14; IgG4 OD, 0.39; IQR, 0.09-1.11; P < .0001 for both) or complete success (IgG total OD, 0.04; IQR, 0.00-0.07; IgG4 OD, 0.07; IQR, 0.06-0.40; P < .0001 for both). Plasma cytokines, chemokines, and anti-FVIII IgG1 were not associated with ITI outcome. ConclusionOur results show that high levels of plasma anti-FVIII IgG4 and IgG total are associated with ITI failure.

Designing and implementation of internet of things (IoT) on physico‐biological treatment of wastewater

AbstractThe use of Internet of Things (IoT) in industries is not new; however, the amalgamation of IoT and Biotechnology is still less explored. IoT in wastewater treatment comes with a full suite including cloud and its corresponding ecosystem. The available cloud‐based systems are advantageous, but costly and tightly coupled to their own cloud infrastructure. Opportunities are limited for the creation of a hybrid/multiple cloud model as it's difficult to integrate with the legacy system(s) and/or customized systems. The current investigation focuses on designing architechture of an open source IoT platform on an effluent treatment plant (ETP) protoype of textile industry. The designed prototype includes physical (adsorption) and biological (Rotating Biological Contactor, RBC, immobilized with white rot fungus) processes. IoT has been used for automated data monitoring of pH and ultrasound (for effluent flow from one tank to another, with respect to the water level, for processing). The process operated under an optimized pH (6.53±0.15) with reduction of representative wastewater quality parameters, biological &amp; chemical oxygen demand, total dissolved solids, total suspended solids and optical density by 78.9, 52.15, 91.6, 20.3 and 88.8%, respectively. The findings demonstrated the reliability of the designed system and the analytics on treatment facilities.

Determination of Thermal Damage Threshold in THz Photomixers Using Raman Spectroscopy

The increase of device lifetime and reliability of THz photomixers will play an essential role in their possible future application. Therefore, their optimal work conditions/operation range, i.e., the maximal incident optical power should be experimentally estimated. We fabricated and tested THz photomixer devices based on nitrogen-implanted GaAs integrated with a Bragg reflector. Raman spectroscopy was applied to investigate the material properties and to disclose any reversible or irreversible material changes. The results indicate that degradation effects in the photomixer structures/material could be avoided if the total optical power density does not exceed levels of about 0.7 mW/µm2 for 100 min of operation. Furthermore, the investigations performed during 1000 min of optical exposure on the photomixer devices’ central region comprising interdigitated metal-semiconductor-metal (MSM) structures suggest a reversible “curing” mechanism if the power density level of ~0.58 mW/µm2 is not exceeded. Long-term operation (up to 1000 h) reveals that the photomixer structures can withstand an average optical power density of up to ~0.4 mW/µm2 without degradation when biased at 10 V. Besides the decrease of the position of the A1g (LO) Raman mode from ~291 cm−1 down to ~288 cm−1 with increasing optical power density and operation time, broad Raman modes evolve at about 210 cm−1, which can be attributed to degradation effects in the active photomixer/MSM area. In addition, the performed carrier lifetime and photomixer experiments demonstrated that these structures generated continuous wave sub-THz radiation efficiently as long as their optimal work conditions/operation range were within the limits established by our Raman studies.

Optimization of textile effluent bacterial treatment and improvement of the process efficiency through SPB1 biosurfactant addition.

The current work aims to optimize biological textile effluent treatment through the use of newly selected bacterial consortia composed of two strains: Citrobacter sedlakii RI11 and Aeromonas veronii GRI. We assessed the effect of SPB1 biosurfactant addition on color removal (CR). The process was optimized by a Box-Bhenken by examining the effect of pH, consortia density and biosurfactant value on treatment efficiency. Firstly, physicochemical analyses of the studied effluent revealed an alkaline pH along with a high content of suspended materials and large amounts of organic matter. Optimal CR and a chemical oxygen demand abatement of about 94 and 86% were obtained when treating the textile effluent at pH 5 with a total optical density of 0.4 and by incorporating 0.01% SPB1 biosurfactant. Additionally, an abolishment of phytotoxicity was registered after treatment optimization. The evaluations of the action mode of both selected bacteria during textile effluent treatment suggested the occurrence of biodegradation phenomena of dyes through enzymatic activities.

Pharmacodynamic Material Basis and Potential Mechanism Study of Spatholobi Caulis in Reversing Osteoporosis.

To elucidate the mechanism of Spatholobi Caulis (SC) in treating osteoporosis (OP) integrated zebrafish model and bioinformatics. Skeleton staining coupled with image quantification was performed to evaluate the effects of SC on skeleton mineralization area (SSA) and total optical density (TOD). Zebrafish locomotor activity was monitored using the EthoVision XT. Bioactive compounds of SC and their corresponding protein targets were acquired from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Potential therapeutic targets for OP were summarized through retrieving 5 databases, and then, the overlapping genes between SC and OP were acquired. The core genes were selected by CytoHubba. Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) functional analysis of the intersection target genes were carried out by R software. Finally, the molecular docking simulation was manipulated between the ingredients and the hub genes. Compared with the model group, SC significantly increased the SSA and TOD at 10 mg/mL and improved the locomotor activity in a dose-dependent manner (p < 0.001). 33 components of SC were associated with 72 OP-related genes including 10 core genes (MAPK1, VEGFA, MMP9, AKT1, AR, IL6, CALM3, TP53, EGFR, and CAT). Advanced Glycation End Product (AGE) Receptor for AGE (RAGE) signaling pathway was screened out as the principal pathway of SC in anti-OP. The bioactive components (Aloe-emodin, Emodin, Formononetin, Licochalcone A, Luteolin, and Lopac-I-3766) have excellent affinity to core genes (MAPK1, VEGFA, MMP9, AKT1, and IL6). SC had the hierarchical network characteristics of "multicomponents/multitargets/multifunctions/multipathways" in reversing OP, but AGE-RAGE signaling pathway may be the main regulatory mechanism.

Kinetics study of bacterial cellulose production by Acetobacter xylinum FNCC 0001 with variation of carbon sources

Glucose and fructose (2.0% (w/v)) were used as the carbon sources and peptone was used as nitrogen source (1.5% (w/v)) in order to determine the kinetics study and yield of bacterial cellulose production. Coconut water was prepared as the fermentation medium. Data of the fermentation rate was observed at 19 points of certain time during 7 days of fermentation process. The number of cell biomass was calculated using cell dried weight method, total plate count method and optical density method which was observed at 660 nm. The remaining media substrate was analyzed using the DNS method, while the BC yield was determined by the gravimetric method. The results showed that the best values of μ, Td, Rx, Rs, Rp, Yp/s, Yp/x were achieved by fructose, while the best n and Yx/s value were achieved by glucose. The corresponding values were 0,1141/h, 6,0737 h, 0,1141 g/L/h, 0,0635 g/L/h, 0,3015 g/L/h, 0,317 g/g, 0,5927 g/g 1,3631 times and 0,0983 g/g respectively. The highest BC yield at the end of fermentation process was achieved by glucose carbon at 5.83 g/L, followed by fructose at 4.91 g/L.

Von Willebrand Factor Multimer Patterns in People Living with Human Immunodeficiency Virus Infection.

Endothelial dysfunction contributes to hypercoagulability in people with HIV (PWH). A surrogate marker of this is elevated von Willebrand factor (VWF) which has been documented in PWH. This study compared VWF multimer patterns in PWH who were anti-retroviral therapy (ART) naive and immune reconstituted on ART. VWF multimer analysis was performed with a semi-quantitative electrophoresis assay on plasma from 79 PWH (39 ART-naive and 40 virally suppressed on ART) and 25 normal control samples. The total optical density mean VWF level was significantly increased in PWH and higher in ART-naive versus ART-exposed, virally suppressed patients (p < 0.0001). No quantitative difference was demonstrated in the multimer distribution pattern between the groups. Our findings suggest that there is no difference in multimer distribution between ART-naive and virally suppressed PWH. Due to a small sample size, confirmation in a larger study is required.

Aspergillus flavus: A degrader of commercial brake fluids

The role of; Aspergillus flavus during the deterioration of brake fluids; was identified. The impact of; A. flavus on used and unused brake fluids; were studied. This research was carried out at the University of Port Harcourt from September 2019 to November 2020. Abro and Jenox DOT3 brake fluids were the samples used for this research. The sample included their unused and used counterpart. Tests to identify microorganisms and physico-chemical parameters; were done. Total viable count, pH and optical density; were tested to check for the level of biodeterioration. Biodeterioration rate was more in Jenox brake fluid than Abro brake fluid. Aspergillus flavus is a major biodegrader in the brake fluid samples. Total viable count and optical density increased as the days progressed during biodeterioration while pH decreased. Brake fluid is an essential fluid needed by most vehicles to function. It is necessary to top-up brake fluid or substitutes; at the appropriate time. No two brands of brake fluid are the same. Therefore, it is advisable not to mix.

Potentials of intravenous laser blood irradiation to correct peroxidation and antioxidant activity as a result of surgical distress

Purpose: to reveal protective effects of intravenous low-level laser blood irradiation (ILBI) during surgical interventions at the gallbladder as well as to study the state of antioxidant activity, lipid peroxidation and endogenous intoxication.Material and methods. In the perioperative period, 40 patients from the main group (I) had traditional treatment which included pharmacological preparations and sessions of intravenous laser blood irradiation. 45 patients from the control group (II) had only traditional (pharmacotherapeutic) treatment. In both groups during surgery, the anesthetic protection consisted of classical neuroleptanalgesia. The age of patients in both groups did not differ significantly. Intravenous laser blood irradiation was done with helium-neon laser “Atoll” 632 nm (Fokon Ltd, St-Petersburg, Russia). During surgery, three irradiation sessions were performed at radiation power of 20 mW and exposure 15 minutes at various stages of surgery: 30 minutes before induction of anesthesia, at the traumatic stage and 30 minutes before the expected finish of the surgery. Ceruloplasmin and transferrin levels in the blood plasma were assessed with the electron paramagnetic resonance technique. The ratio of ceruloplasmin/transferrin which characterizes the level of antioxidant activity was also established. The level of endogenous intoxication was assessed using the previously published technique. The quantitative characteristics of endogenous intoxication by this technique is the value of optical density (D280) and total optical density of components related to high molecular weight and low molecular weight fractions.Results. ILBI sessions in patients neutralize changes in the level of ceruloplasmin and transferrin in blood. The data obtained also confirm ILBI protective effects at protein SH-groups or activation of the restoration of protein SH-groups that were damaged by oxidation as a result of surgical aggression and trauma.Conclusion. The protective effect of intravenous laser blood irradiation in addition to the standard preoperative therapy optimizes pharmacological anesthetic protection during surgery under the existing traditional schemes of combined general anesthesia.

Optimization of an effective growth medium for biomass production of Bacillus cereus

Protein is the main source of nutrition in fish feed. It is necessary to use bacterial single-cell protein (SCPs) as a substitute for conventional protein. This study aims to determine the effectiveness of tofu liquid waste as a growth medium for biomass production of Bacillus cereus as an SCPs. The isolates used were B. cereus SN7 and B. cereus consortium (combination of 5 isolates of B. cereus with different strains). The method used was experimental where isolates were cultured in a medium containing tofu liquid waste with different concentrations (8%, 10%, and 12%) enriched with 10% skim milk. Furthermore, the analysis of an effective growth medium was carried out by three methods, namely total plate count, optical density, and cell-dry weight. Cell biomass measurements were carried out for 24 hours with an observation time of every 6 hours. The results showed the best growth medium used in the culture of B. cereus SN7 and B. cereus consortium was tofu liquid waste at a concentration of 12% enriched with 10% skim milk. In conclusion, the cell mass of B. cereus SN7 and B. cereus consortium significantly increased at 6 to 12 hours.

The evolution of physicochemical and microbiological properties of green and mature coconut water (Cocos nucifera) under different storage conditions

The effect of storage temperature and time on physicochemical (total soluble solids, pH, titratable acidity, and optical density) and microbiological (total plate count and yeast and mould count) properties of green (GC) and mature coconut (MC) water were determined between 4 and 35 °C for up to 24 h. When held at temperatures above 25 °C, total soluble solids of coconut water reduced slightly, whereas pH decreased concomitantly with the increase in titratable acidity. These changes correlate positively with storage temperature and occurred at a faster rate in MC water than in GC. Both GC and MC could be held at temperatures between 25 and 35 °C for up to 12 and 6 h, respectively, after which the samples could become acidified and microbiologically unsafe to be consumed. At 4 °C, both GC and MC could be held for 24 h with acceptable microbiological counts.

Monitoring and bioremediation of organochlorine pesticides in surface water with Enterobacter asburiae

Aim of study: One of the safest techniques regarding the remediation of contaminated water is biological remediation. This study aimed to: (i) monitoring of a collection of organochlorine pesticides (OCPs) in three agricultural drainages (Nashart, no. 9, and El-shoka), located in Kafr El-Sheikh governorate, Egypt; and ii) investigate the biodegradation potential of different bacterial isolates regarding organochlorine pesticides.Material and methods: Analysis of OCPs was carried out by gas chromatography, Enrichment cultures were used for isolation of the bacterial strains capable of OCPs biodegradation and the most efficient isolate was identified based on morphological, biochemical ad molecular characteristics.Main results: The determination of OCPs in water samples by gas chromatography showed varying values of OCPs ranging from 0.0 mg/L (below detection limit) to 0.0385 mg/L. A total of four morphologically different bacterial isolates were obtained, which showed a remarkable capability of OCPs biodegradation detected in mineral salt medium containing 17 OCPs active ingredients by two approaches including the analysis of the OCP residues at the end of the incubation period and measuring the bacterial growth in terms of total viable count and optical density. The bacterial isolate N2 showed the highest degradation capability when the screening process was carried out to select the most efficient isolates, which was identified according to the morphological, biochemical and molecular characterization as Enterobacter asburiae.Research highlights: The biodegradation of OCPs using E. asburiae was proved to be a promising approach for the detoxification and removal of OCPs residues in aqueous systems.

Biofouling of FeNP-Coated SWRO Membranes with Bacteria Isolated after Pre-Treatment in the Sea of Cortez

Commercial seawater reverse osmosis (SWRO) membranes were coated with iron nanoparticles (FeNPs) and biofouled with a bacterium strain isolated from the Sea of Cortez, Mexico. This strain was selected and characterized, as it was the only cultivable strain in pretreated seawater. Molecular identification of the strain showed that it belongs to Bacillus halotolerans MCC1. This strain was Gram positive with spore production, and was susceptible to Fe+2 toxicity with a minimum inhibitory concentration of 1.8 g L−1. Its biofouling potential on both uncoated and FeNP coated reverse osmosis (RO) membranes was measured via biofilm layer thickness, total cell count, optical density and organic matter. The FeNP-coated RO membrane presented a significant reduction in biofilm cake layer thickness (&gt;90%), total cells (&gt;67%), optical density (&gt;42%) and organic matter (&gt;92%) with respect to an uncoated commercial membrane. Thus, Bacillus halotolerans MCC1 shows great potential to biofoul RO membranes as it can pass through ultrafiltration membranes due to its spore producing ability; nonetheless, FeNP-coated membranes represent a potential alternative to mitigate RO membrane biofouling.

A Wirelessly Controllable Optoelectronic Device for Optogenetics

The purpose of this letter is to report a new optoelectronic device which consists of a wirelessly controllable driver circuitry and a slender implantable optical probe. Instead of the conventional silicon substrate, the probe is based on GaN material growing on a sapphire substrate. Thin-film blue micro light-emitting diodes (μLEDs) with a total optical power density of 176.9 mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 1 mA are directly fabricated at the probe by semiconductor device fabrication technologies. In a further research, we integrate a yellow μLED on the probe to enable optical stimulation of both excitatory and inhibitory neurons. Besides, we adopt Bluetooth 4.0 wireless communication protocol; therefore, light emitting from the μLEDs can be remotely controlled by a terminal with a distance as far as 20 m. The driver is also equipped with an accelerometer, a power management module, and a system-on-chip (SoC), and they are energized by a rechargeable lithium battery that has up to 10-h battery life. The whole device is a little bit bigger than a coin and weighs approximately 6 g. The probe has a length of 1.65 cm and a thickness of 150 μm. These features make the device suitable for a broad variety of optogenetic experiments.

Effect and mechanism of PCSK9 on lectin-like oxidized low-density lipoprotein receptor-1 mediated oxidized low-density lipoprotein uptake by THP-1 derived macrophages

Objective: To investigate the effect and mechanism of proprotein convertase subtilisin type 9 (PCSK9) on lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) mediated oxidized low-density lipoprotein (ox-LDL) uptake by mononuclear macrophage (THP-1) derived macrophages. Methods: THP-1 monocyte was incubated with PMA for 48 hours to induce the differentiation into macrophages. Macrophages were pretreated with human recombinant PCSK9 protein for 1 hour and incubated with ox-LDL for 24 hours to induce foam cells. Oil red O staining was used to observe the accumulation of lipid in the control group (foam cells) and groups treated with different concentrations of recombinant PCSK9 protein, and the intracellular cholesterol content was measured by enzyme method, and mRNA and protein expressions of LOX-1 were detected by real-time PCR and Western blot. The uptake of Dil-labeled oxidized low density lipoprotein (Dil-ox-LDL) was observed by fluorescence microscopy in control group (macrophage), PCSK9 protein treated group and PCSK9 protein plus anti-LOX-1 antibody and IgG antibody treated group. mRNA and protein expression of toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (COX-2) were detected in control and PCSK9 protein treated group in the absence and presence of TLR4 inhibitor (TAK-242), NF-κB inhibitor (PDTC). In addition, reactive oxygen species (ROS) production was evaluated in the absence or presence of COX-2 inhibitor (NS-398) or reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor (DPI). The mRNA and protein expression of LOX-1 in the control group (PCSK9 protein pretreated foam cells) and PCSK9 protein group in the absence or presence of TAK-242, PDTC, NS-398 and DPI respectively. Results: (1) The total optical density of intracellular lipid droplets, total cholesterol level, cholesterol ester level and cholesterol ester/total cholesterol ratio as well as expression of LOX-1 were significantly higher in PCSK9 group than those in control group (all P<0.05). (2) The fluorescence intensity of Dil-ox-LDL was significantly higher in PCSK9 group and PCSK9+IgG antibody group than in the control group (all P<0.05). The fluorescence intensity was significantly lower in PCSK9+anti-LOX-1 antibody group than in PCSK9 group and PCSK9+IgG antibody group (all P<0.05). (3) The expressions of TLR4, NF-κB and COX-2 were significantly higher in PCSK9 group than in control group (all P<0.05). The expressions of TLR4, NF-κB and COX-2 were significantly lower in PCSK9+TAK-242 group and PCSK9+PDTC group than in PCSK9 group (all P<0.05). The ROS level was significantly higher in PCSK9 group than in the control group (P<0.05). The ROS levels were significantly lower in PCSK9+NS-398 and PCSK9+DPI groups than in PCSK9 group (all P<0.05). (4) The expressions of LOX-1 mRNA and protein were lower in respective PCSK9 protein plus TAK-242, PDTC, NS-398 or DPI group than in PCSK9 protein alone (all P<0.05). Conclusion: PCSK9 may regulate LOX-1 mediated ox-LDL uptake by the THP-1 derived macrophage via TLR4/NF-κB/COX-2/ROS pathway.

Topical cyclosporine-A versus prednisolone for herpetic stromal keratitis: a randomized controlled trial.

To compare topical cyclosporine-A 2% eye drop (Cs-A) with prednisolone acetate 1% eye drop for treatment of herpetic stromal keratitis (HSK). In this randomized clinical trial, 38 eyes of 33 patients with HSK were randomly assigned to receive either 2% Cs-A or 1% prednisolone acetate eye drops. All subjects received oral acyclovir 400mg twice a day. Slit-lamp examination, Scheimpflug tomography corneal optical densitometry (Pentacam®, Oculus Inc., Wetzlar, Germany), best-corrected visual acuity (BCVA), and intra-ocular pressure (IOP) were evaluated at the first visit, and 14 and 30days after the treatment. Within-group analysis revealed significant improvement of total cornea optical density after 30days of treatment in both groups (30.3±10.5 to 28.3±9.8, p<0.001 for prednisolone group, and 30.5±8.8 to 28.8±8.3 p<0.001 for Cs-A group, mean±SD). We were not able to disclose any significant difference between the two groups regarding the improvement of cornea optical density (p=0.66). Best-corrected visual acuity (BCVA) logMAR significantly improved in both groups after 30days of treatment (0.20±0.52, p=0.002 in prednisolone group, and 0.24±0.31, p<0.001 in Cs-A group, mean±SD). Analysis between groups did not show a significant difference of BCVA improvement (p=0.45). We did not observe any severe side effect attributable to drugs. Cs-A 2% and prednisolone acetate 1% topical eye drops are effective for treatment of HSK.

Flame-retardant and smoke-suppressant flexible polyurethane foams based on reactive phosphorus-containing polyol and expandable graphite

In this manuscript, flame-retardant and smoke-suppressant flexible polyurethane foams (FPUFs) were designed and synthesized based on novel liquid phosphorus-containing polyol named as PDEO and expandable graphite (EG). The reactive PDEO can be chemically added into the chain of FPUF, while expandable graphite was blended into the matrix of foam through foaming process. Benefitting from the incorporation of reactive PDEO with a long chain, the resultant FPUF containing EG exhibited considerable mechanical properties. More importantly, the synergistic effect of PDEO and EG can endow FPUF with great flame retardancy, anti-driping performances. Furthermore, the resultant FPUF/EG/PDEO foams exhibit considerable smoke suppression performances. The vertical burning test revealed that the FPUF containing 5 php PDEO and 10 php EG extinguished quickly without dripping and kept the original shape after removing the igniter. The cone calorimeter results demonstrated that the synergistic effect of PDEO and EG can effectively reduce the heat release rate (HRR) and total release rate (THR) of the composite foam. Remarkably, the smoke production release (SPR), total smoke production (TSP), light transmission and specific optical density results indicated significantly smoke-suppressant properties of the composite foam. The mechanism analysis confirmed that the synergistic effect of gas-condensed bi-phase action from PDEO and EG contributed the great flame retardation of the composite foam. This novel FPUF provides a promising strategy for producing the polymer foam with flame retardation, smoke suppression and anti-dripping performances.

Biofouling performance of RO membranes coated with Iron NPs on graphene oxide

Biofouling performance was evaluated for polyamide commercial RO membranes coated with iron nanoparticles (FeNPs) and graphene oxide (GO), under controlled conditions using a cross-flow system. Feed water obtained from the Sea of Cortez, Mexico, was pretreated, sterilized and inoculated with a high concentration (109 CFU mL−1) of Bacillus halotolerans MCC1, isolated from the Sea of Cortez. The zeta potential was determined for FeNPs and GO–FeNPs. XRD, roughness, contact angle, permeance and flux were determined for the coated and uncoated membranes. To evaluate the anti-biofouling effect, total organic carbon, total cell count, optical density and percentage of live/dead cells were determined for the biofilm. The GO–FeNP coating showed less agglomeration tendency and surface roughness compared to pure FeNP, and contact angle (49.1° ± 4.3°) similar to the uncoated membrane (50.2° ± 4.3°). Despite reducing the membrane permeance, the FeNP and GO–FeNP coatings presented larger fluxes after fouling (18% and 5.3% larger, respectively) than the fouled uncoated membrane. This was corroborated by both FeNP and GO–FeNP coated membranes presenting reduced biofilm layer thickness (89% and 65% thinner), total cell count (67% and 40% lower), optical density (40% and 48% lower) and total organic carbon (91% and 98% lower), than the uncoated membrane.

Synergistic effects of aluminum hydroxide on improving the flame retardancy and smoke suppression properties of transparent intumescent fire-retardant coatings

A series of novel aluminum phosphate ester (APEA) flame retardants were synthesized by the salification of cyclic phosphate ester acid (PEA) with different mass ratios of aluminum hydroxide (ATH) and thoroughly characterized by Fourier transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance spectroscopy. The PEA and APEAs were thoroughly mixed with melamine formaldehyde resin to produce five kinds of transparent fire-retardant coatings. The synergistic effects of ATH on the thermal stability, flame retardancy, and smoke suppression properties of the coatings were investigated by different analytical instruments. The results show that the incorporation of ATH greatly decreases the weight loss, char index, flame spread rating, heat release rate, total heat release, smoke production rate, total smoke release and specific optical density in the coatings applied to plywood boards, which is ascribed to a more compact and intumescent char formed during burning, as determined from digital photographs and scanning electron microscopy images. The synergistic effects of ATH in the coatings depend on the content of ATH, and an excessive amount of ATH diminishes the synergistic effects on the flame retardancy and smoke suppression properties based on fire protection tests and cone calorimeter test. Thermo-gravimetric analysis reveals that the thermal stability and char-forming ability of the coatings gradually improve with increasing loading of ATH. FTIR analysis demonstrates that the incorporation of ATH forms a more phosphorus-rich crosslinked char and aromatic char during burning, thus effectively reducing the mass loss, heat release, and smoke production and exhibiting excellent synergistic flame retardant and smoke suppression effects in the coatings.

Enhancing the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings by introducing boric acid as synergistic agent

A series of novel phosphorus-boron flame retardants (BPEAs) were successfully synthesized by introducing boric acid (BA) into cyclic phosphate ester acid (PEA) via the esterification and thoroughly characterized by 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Five kinds of transparent fire-retardant coatings applied to wood substrates were produced by thoroughly mixing amino resin with PEA and BPEAs. The effects of BA on the optical transparency, thermal stability, fire performance and smoke emission characteristics of the coatings were investigated by various analytical instruments. The transparency analysis reveals that the transparency value of the coatings gradually decreases with increasing BA loading, and MPEA4 with the highest BA content still exhibits a high degree of transparency. The results from fire protection, cone calorimeter and smoke density tests show that the introduction of BA greatly decreases the flame spread rating, mass loss, char index, heat release rate, smoke production rate, total heat release, total smoke release and specific optical density of the coatings concomitant with the increase in the residual mass and intumescent factor, which is ascribed to the formation of a more dense and continuous intumescent char judging by digital photographs and scanning electron microscope images. Thermo-gravimetric analysis indicates that the onset decomposition temperature, high-temperature stability and residual mass of the coatings greatly improve with increasing BA content. FTIR analysis shows that the introduction of BA into the coatings contributes to generate more phosphorus-rich cross-linked structures and aromatic structures and then create a compact and intumescent char layer, thereby effectively enhancing the flame retardancy and smoke suppression properties of the coatings.