The amphiphilic hybrid MXene/POSS monolayers allow forthe fabrication of organized multilayered films with ionic nanoparticlessupporting the nanoscale gap between MXene nanosheets. For these compositemultilayers, we observed a 400% enhancement in specific capacitancecompared to pure drop-cast MXene films. Furthermore, dramaticallyenhanced electrochemical cycling stability for ultrathin-film electrodes(<400 nm in thickness) with a 91% capacitance retention over 10,000cycles has been achieved. Our results suggest that this insertionof 0D ionic nanoparticles with complementary interactions in between2D MXene nanosheets could be extended to other hybrid 0D–2Dnanomaterials, providing a promising pathway for the development ofhybrid electrode architectures with enhanced ionic transport for long-termenergy cycling and storage, capacitive deionization, and ionic filtration.Two-dimensional(2D) materials such as MXenes have shown greatpotential for energy storage applications due to their high surfacearea and high conductivity. However, their practical implementationis limited by their tendency to restack, similar to other 2D materials,leading to a decreased long-term performance. Here, we present a novelapproach to addressing this issue by combining MXene (Ti We suggest that POSS nanoparticlesare placed in between the multilayers and hinder MXene restacking.Furthermore, the formation of POSS-supported channels facilitatesthe enhanced ion transport across loosely packed 2D MXene nanosheets.Overall, this work provides a route for designing hybrid ultrathin-filmelectrodes with controlled architectures for enhanced energy storageand long-term cycling stability.Here, we report novel multilayered supercapacitor MXene/POSSultrathinfilms (<400 nm in thickness) as electrodes with improved cyclingstability compared to their single-component MXene counterpart. Wedemonstrate that the introduction of ionic branched amphiphilic POSSnanoparticles with variant peripheral composition stabilizes the MXenenanosheets at the air–water interface and allows for the fabricationof hybrid monolayers with MXenes nanosheets decorated with ionic POSSnanoparticles. Indeed, atomic force microscopy (AFM) revealed theformation of monolayers composed of micellar POSS nanoscale domainsin between the MXene nanosheets depending on POSS peripheral hydrophilic/hydrophobicbalance. The addition of ionic POSS nanoparticles not only stabilizesthe MXenes at the air–water interface but also facilitatessignificantly improved energy storage performance and stability. Thecapacitance values of 17 mF/cm22.1Figure S1.19 POSS oligomers were dispersed in ethanolat a concentration of 0.05 mg/mL for experiments in this work.POSSoligomers were synthesized as mixtures of oligomeric silsesquioxaneswith a polyhedral structure and their analogs with open chains. Detailedsynthesis steps and chemical characterization are included in priorpublication and illustrated in 2.23C2Tx  wassynthesized as previously reported, and highlyconcentrated (9 mg/mL) dispersions of MXene flakes in DI water wereobtained (see the Supporting Information for more details).21 The dispersionswere then diluted with DI water:ethanol 1:5 (v:v) to a concentrationof 0.05 mg/mL.Ti2.323 MXene dispersionsat a concentration of 0.05 mg/mL were spread on the aqueous subphasedropwise and left undisturbed to allow ethanol to slowly evaporatefor 30 min. Equal amounts of solutions of the POSS oligomers in ethanolat a concentration of 0.05 mg/mL were then added similarly. Once allof the solvent was evaporated, compression isotherms were obtainedat a rate of 5 mm/min. LB monolayered films were obtained by verticaldipping of the substrates at a rate of 1 mm/min at selected surfacepressures. Multilayered LB films were obtained by repeated verticaldipping on a single substrate with a 30 min waiting time between eachdeposition cycle at a surface pressure of 15 mN/m. This surface pressurewas selected because it led to good MXene surface coverage with noaggregations, allowing for a higher electrolyte accessible surfacearea.A KSV 2000 minitrough was used to obtain the Langmuirisotherms andthe LB films on piranha-treated silicon wafers and indium tin oxide(ITO) glass (thickness: 1.1 mm).2.42SO4 gel electrolyte. The gel electrolyte was preparedby adding 1 g of PVA in 10 mL of deionized water.24 The mixture was heated at 80 °C for 1 h under stirring.24 Then, the mixture was left to cool down to roomtemperature and 0.5 mL of H2SO4 was added.24 The gel electrolyte was spread between the twoLB electrodes, and polyimide tape (Bertech) was placed around thesupercapacitor to provide external insulation. The total thicknessof the supercapacitor was ∼2.5 mm, the electrolyte thicknesswas ∼0.3 mm, the ITO substrate thickness was 1.1 mm, and theMXene/POSS thickness varied from 100 to 400 nm depending on the numberof layers and the POSS peripheral composition, as discussed in moredetail in later sections. The active electrode area was 2.5 cm2.Two-electrodesymmetric supercapacitors were fabricated using two of the LB multilayeredfilms coated on ITO glass and a poly (PVA)/H2.5Zeta potential anddynamic light scattering (DLS) measurements of MXenes, POSS oligomers,and their mixtures in water (0.1 mg/mL) were conducted using a ZetasizerNano ZS (Marven Instruments) at 633 nm and a scattering angle of 173°.Polystyrene cuvettes were used, and an average of three measurementswas obtained.UV–vis spectroscopy measurements were conductedusing a Shimadzu UV-3600 Plus Spectrophotometer within 300–800nm.Contact angle measurements were performed by drop-casting40 μLof water droplets onto the multilayered films. Images were taken withinthe first 10 s of the water droplet application using a KSV CAM101system.Scanning electron microscopy (SEM) images were obtainedon a HitachiSU-8230 electron microscope operated at 3 kV voltage without sputtering.For the cross-sectional images, the samples on ITO glass were attachedperpendicular to the SEM mount. Samples were sputter-coated with goldfor 45 s at 30 mA (the resulting gold layer thickness is ∼3nm). EDX was performed using a Hitachi-3400SN SEM instrument withOxford EDX on unsputtered films.25 High-resolution scans were collected using ultrasharp AFMprobes  with 1 nm tipradius and 2.8 N/m spring constant. All scans were collected witha scan rate of 0.5 Hz and a resolution of 512 × 512.AFM was conducted by usinga Bruker Dimension Icon microscope.AFM images were collected at tapping mode in air using AFM probes(HQ:XSC11/AI BS) with a tip radius of 8 nm and a spring constant of3–16 N/m according to the usual procedure.hm = 1476 eV) radiation.Survey scans (average of two scans) were collected with a dwell timeof 50 ms and a step size of 1.0 eV. High-resolution scans (averageof 10 scans) were collected with a dwell time of 50 ms and a stepsize of 0.1 eV. The C 1s peak at 284.5 eV for sp2-hybridizedcarbon atoms was used to calibrate all spectra. Background corrections(Shirley) and Gaussian–Lorentzian (GL) peak shape fitting wereperformed using CasaXPS. The fwhm and position of the peaks were constrainedto perform the deconvolution of the high-resolution C 1s and Ti 2ppeaks, and the Ti 2p1/2 and 2p3/2 componentswere constrained so that the area ratio would be 2:1.27X-rayphotoelectron spectroscopy (XPS) measurements of the multilayeredfilms were conducted using a Thermo K-Alpha XPS instrument from ThermoScientific with Al Kα (X-ray diffraction (XRD) measurements were performed usinga RigakuSmartLab SE with Co Kα radiation and Bragg–Brentano beam(BB) optics. Measurements were conducted with a step size of 0.01and a rate of 10°/min.C = 2· V is the voltage, I is the current, ΔV is the potentialwindow, ν is the scan rate, and a is the areaof the two electrodes.28 Electric conductivity was measuredusing an Agilent E5272A source/monitor unit.Electrochemical testing was conductedby using VersaSTAT3 and ZahnerZennium potentiostats. All supercapacitors were preconditioned at20 mV/s for 10 cycles. Cyclic voltammetry was conducted at variantscan rates from 5 to 100 mV/s within a potential window of 0–0.6V. The specific capacitance was calculated using the equation 2 with a potential window of 0–0.6 V, and the specificcapacitance was calculated from the equation C =4·t is thedischarge time. Finally, the specific energy was calculated usingthe equation E = C·ΔV2.3 Electrochemicalimpedance spectroscopy (EIS) measurements were conducted at the opencircuit potential (OCP) with 10 AC mV amplitude in a frequency rangeof 1 MHz to 10 mHz.Prolonged retentionexperiments up to 10,000 cycles were conductedat a scan rate of 20 mV/s. Charge–discharge experiments wereconducted at variant current densities of 0.02–0.1 mA/cm33C2Tx MXenes (30 Synthesized POSS nanoparticles have diameters of 2.7 nm with narrowsize distribution.19AFM topographyimages of drop-cast aqueous dispersions show MXene(MX) nanosheets with a thickness of 1.7 ± 0.4 nm, a length of4.8 ± 1.2 nm, and a width of 2.5 ± 0.9 nm, similar to previousreports on Tix MXenes 1.29,30 SFigure S3).After adsorption, the functionalized POSS withshort alkylchains(POSS-2) formed flat disklike micelles with diameters of 69.7 ±9.7 nm and heights of 6.8 ± 2.0 nm, while POSS with longer alkylchains (POSS-9) formed flat cylindrical micelles with lengths of 115.6± 14.9 nm, widths of 73.6 ± 6.8 nm, and heights of 9.8 ±2.2 nm .31 On the corresponding nanoparticlesuspension, POSS-2 had hydrodynamic diameters of 72 ± 6 nm withζ-potential values of 30 ± 2 mV and POSS-9 exhibited diametersof 140 ± 40 nm with ζ-potential values of 41 ± 2 mV.Overall, the MXene nanosheetcomponent in aqueous dispersions hadhydrodynamic diameters of 1600 ± 390 nm and ζ-potentialvalues of −27 ± 1 mV . Furthermore, ζ-potentialsshifted to 10 ± 1 and 19 ± 1 mV for MX/POSS-2 and MX/POSS-9,respectively. The dramatic changes in ζ-potential values areindicative of dominating surface charge screening of the MXene surfacegroups, resulting from the adsorption of the POSS nanoparticles onthe MXene nanosheet surfaces.35The additionof POSS to the MXene dispersions caused decreasedhydrodynamic diameter values of 1320 ± 40 and 1290 ± 190nm for MX/POSS-2 and MX/POSS-9, respectively, due to the introductionof the much smaller POSS-2 and POSS-9 nanoparticles .Figure S6). As shown in Figure S7, these interactionsdo not allow the full recovery of the initial morphologies, resultingin compacted morphologies during the second compression cycle thatis, in contrast, completely reversible.41Upon decompression, the Langmuir isothermsfor MX/POSS-2 and MX/POSS-9show large hysteresis that can be attributed to the strong interfacialinteractions between the positively charged ammonium terminal groupsof the POSS particles and the negatively charged surface groups ofthe MXene flakes as well as to hydrogen bonding interactions betweenthe nanoparticles and the flakes . Specifically, at a pressure of 2 mN/m, single MXene nanosheetswith POSS micelles of 5.0 ± 0.5 nm in height and 200 ± 12nm in diameter spread between the MXenes were observed for MX/POSS-2.At the same pressure, only MXene nanosheets were visible for the MX/POSS-9monolayers. Higher surface pressures led to more compact morphologiesin both cases. Specifically, at 10 mN/m, MX/POSS-2 showed aggregatedMXene nanosheets with larger POSS micelles of 17 ± 2 nm in heightand 400 ± 50 nm in diameter spreading between the MXene nanosheets.Morphologicalchanges during compression were observed for POSSswith different alkyl chain peripheral compositions .These observations were furtherconfirmed using UV–vis spectroscopy,where a linear increase in absorbance with the number of layers andhigher absorbance values for the MX/POSS-9 films were also observed measured for the first layers formedunder the same conditions. Similarly, the thickness of the MX/POSS-9multilayered films increased to 230 ± 11 nm as the number oflayers increased to 40, which corresponds to the effective thicknessof 5.6 nm per layer, which is much lower than 9 nm for the first monolayer.Figure S10).Indeed, d-spacing values of 0.84–0.88 nm werecalculated by the very broad peak at 11.5–12.3°, whichcorresponds to the (002) plane of MXenes.43 These values are comparable to the d-spacings reportedin the literature for pure MXenes (∼ 0.9 nm), thus confirmingno expansion of intersheet spacing in the presence of POSS nanoparticles.We suggest that the differences in the layer thickness in the multilayersas compared to their first monolayer initially deposited on siliconindicate that the initial gaps between the nanosheets and nanoparticlesare intermixed during sequential deposition, leading to higher connectivitywithin and across adjacent layers and, thus, reduced effective thicknessof further mixed layers. According to AFM images, the POSS nanoparticlesare mostly located at the air gaps between the MXene stacks and veryfew of them adsorbed on the flake surface. Furthermore, no clear evidenceof intercalation in between individual MXene nanosheets in multilayeredfilms was found with XRD . Furthermore, the higher thickness ofthe MX/POSS-2 films as compared to the MX/POSS-9 films can be attributedto the larger sizes of the aggregated POSS-2 micelles prepared underthe same surface pressure. The aggregated micelles and their presencein intersheet areas increase the effective thickness of the mixedmonolayers, subsequently increasing the total effective thicknessof the multilayered films without significant intercalation.Finally, the uniform surface coverage of the multilayers with interconnectednanosheets and micelles was confirmed using SEM . Furthermore, increasing the numberof layers led to rougher surfaces composed of wrinkled MXene flakes.Indeed, the RMS roughness increases from 1.2 ± 0.3 nm  to 13.8 ± 2.1 nm (for 40 layered films) for the MXene-coveredareas (1 × 1 μm surface areas). On the other hand, thechanges in the peripheral composition of POSS nanoparticles did notlead to significant changes in the surface morphology of the differentmultilayered films. We suggest that POSS micelles remain trapped betweenthe deposited layers and do not significantly alter the final surfacemorphology which is dominated by the densely packed MXene nanosheets.AFM topography images revealed the presence of individual largeMXene flakes on the surface of multilayers composed of 20 and 30 layers(Table S2). XPS survey scans of pure drop-cast MXene films revealed a compositionof 51.9 at % carbon, 20.9 at % oxygen, 18.9 at % titanium, and smallamounts (<7 at %) of fluorine and chlorine, which is similar toother reports on MXenes.30 The hybrid multilayered films exhibited additional peaks attributedto nitrogen (1.1–1.9 at %), silicon (5.9–6.2 at %),and bromine (1.1–1.7 at %) resulting from the silsesquioxanecores, tertiary nitrogen atoms, and bromine counterions of the modifiedPOSS nanoparticles within multilayered films. Furthermore, all filmsshowed strong C–Ti-Tx (6.6–12%)resulting from the MXene nanosheets. Deconvoluted C 1s peaks furtherverified the presence of the buried POSS nanoparticles (Table S3). The presence of POSS was further verifiedby EDS Si mapping of the surface of the composite multilayered films.The presence of buried POSS nanoparticles underneaththe MXenenanosheets was verified by using XPS  showed no significant changes with POSS nanoparticle addition,indicating that the MXene nanosheets remained intact in the mixedlayer.Indeed, the composite multilayered films showedC–Si peaks(7.7–10.2%) from the POSS cores in addition to C–C (42.9–56%),C–O/C-N (20.1–28.5%), and COO (5.0–5.3%) bondsassociated with the MXenes and/or POSS nanoparticles for all films.High-resolution Ti 2p peaks .46 On the other hand, drop-cast MX with similar thickness values (300nm) showed highly polarized CVs, indicating ion-diffusion limitationspossibly resulting from the highly aggregated, compacted MXene assemblieswithout a preferred orientation.48 Drop-castMX films exhibited areal capacitance values of 3.5 ± 0.3 mF/cm2 at 1 mV/s, comparable to previous reports using gel electrolytes.51First, all MX/POSS supercapacitors fabricated hereexhibited pseudorectangularcyclic voltammograms (CVs), indicative of the electric double formation. Specifically,MX/POSS-2 films of 20 layers had capacitance values of 7.1 ±0.5 mF/cm2 and MX/POSS-9 films of 20 layers had capacitancevalues of 11.0 ± 0.6 mF/cm2 at 1 mV/s. Increasingthe number of layers leads to higher capacitance values due to theincrease in the electrochemically active material content.46It is important to note that the addition of POSS nanoparticlesled to significantly higher areal capacitance values despite the increasedhydrophobicity and the decreased electric conductivity from 46 ±3 S/cm for drop-cast MX to 35 ± 1 S/cm for MX/POSS-2, 40L, and27 ± 1 S/cm for MX/POSS-9, 40L, due to the dilution of the conductiveMXene nanosheets (52 This suggestion was further confirmed by a decrease inthe charge transfer resistance (Rtc) from1.2 kΩ for drop-cast MX to 0.9 kΩ for MX/POSS-2, 40L,and 0.5 kΩ for MX/POSS-9, 40L .Moreover, MXene/POSS electrodes exhibiteda much higher long-termstability under cyclical loading 7d. This Figure S21 and 2 and a power density of 30 μWh/cm2, whichis comparable to the literature data.53 The addition of POSS-2 and POSS-9 nanoparticles led to 267 and 467%increases in energy density, respectively.Next, the energy and power density were calculated fromgalvanostaticcharge–discharge experiments, and they are summarized in aRagone plot for drop-cast MX, MX/POSS-2, 40L, and MX/POSS-9, 40L,films (3C2Tx (LB-deposited), Ti3C2Tx SC (spray-coated), Ti3C2Tx LP (laser-printed), Ti3C2Tx/amine-functionalized(f-Ti3C2Tx) LbL(layer-by-layer), Ti3C2Tx/RuO2/silver nanowires (Ag NW) SP (screen-printed),and non-MXene-based, such as rGO LbL and rGO/carbon nanotube (CNT)LbL.58 Within this class, Ti3C2Tx/RuO2/Ag NW exhibited the highest energy densityvalue (0.38 μhW/cm2 at 31.3 μW/cm2). The high performance of Ti3C2Tx/RuO2 is attributed to pseudocapacitivecontributions arising from RuO2 and the highly conductivecontinuous network of Ag nanowires.58 Overall,from the analysis of these results, we can conclude that the hybridMX/POSS-9, 40L, film shows second to the best energy density storageability.Furthermore, we comparedthese results against other MXene-basedsupercapacitors, including TiFigure S22 and Table S5).Finally, we observed improved cycling stability forthe MX/POSSsupercapacitor materials. For these measurements, prolonged cyclicvoltammetry  was conducted at 20 mV/s 7d. For t52 Indeed, MXene-based electrodes reported to date frequentlyshow irreversible capacitance loss, which usually leads to poor cyclingstability with capacitance retentions of 46–90% after 500 to5000 cycles.55 The irreversible capacitance loss is typicallyattributed to restacking of the MXene nanosheets, leading to insufficientelectrolyte ion diffusion, as well as to MXene oxidative degradation,deteriorating electronic conductivity.59 As shown in Table S6, in contrast, the improvedcycling stability of the POSS-containing supercapacitors studied hereis noteworthy in direct comparison with literature results on ultrathin-film(<500 nm electrode thickness) supercapacitors.58 Recent exceptions include reports on thick (>5 μm) shear-delaminatedMXene electrodes with good cycling stability up to 500,000 cyclestested in a three-electrode configuration, while other strategiesto achieve high capacitance retention include the development of three-dimensionalelectrodes.61The enhanced cycling stability of the hybrid electrodescan alsobe attributed to the aggregation of POSS nanoparticles at the airgaps in between the stacked layers that prevent, to a great extent,further MXene restacking during prolonged cycling.4In conclusion, we designedand fabricated uniformly stacked hybridMXene/POSS thin films with controlled thicknesses and high surfacecoverage at the air–water interface. Overall, the ultrathin-filmhybrid POSS-containing MXene supercapacitor demonstrated greatly enhancedelectrochemical stability compared to that of the corresponding pureMXene drop-cast films with comparable thickness.The investigationof various compositions of POSS nanoparticlesrevealed their impact on the morphology of Langmuir monolayers andthe corresponding multilayered films. Specifically, POSS nanoparticleswith shorter alkyl chains formed larger aggregates between the MXenenanosheets due to hydrogen bonding and ionic interactions, while sterichindrance interactions were limited. The resulting electrodes exhibitedenhanced power density and superior cycling stability in comparisonwith pure MXene drop-cast thin-film electrodes. These electrodes demonstratedup to 91% capacitance retention after 10,000 cycles. The enhancedenergy storage performance can be attributed to the uniform depositionof MXene nanosheets at the air–water interface due to the mediationof the amphiphilic POSS micelles and the formation of porous channelswithin POSS micelles that facilitate ion transport. Furthermore, thepresence of POSS micelles trapped in the open space between MXenenanostacks prevents further MXene restacking, thus improving the electrochemicalstability during long-term cycling. This work provides an efficientroute for the assembly and fabrication of hybrid thin-film electrodesutilizing 2D nanomaterials with enhanced ionic transport and energystorage capabilities. This approach may be equally useful when designingMXene electrodes for capacitive water deionization or developing sensorsand ionotronic devices.


Pseudomonas PS27 cells—a bacterial strain described for its ability to handle very toxic organic solvents and perfluorinated compounds—to grow as planktonic cells. Moreover, the best formulations  could prevent Pseudomonas PS27 biofilm formation at a certain concentration (250 μg mL−1) which greatly impaired bacterial planktonic growth. Specifically, 15HQ-POSS/5CuTi completely impaired cell adhesion, thus successfully prejudicing biofilm formation and proving its suitability as a potential antifouling agent. Considering that most studies deal with quaternary ammonium salts (QASs) with long alkyl chains (>10 carbon atoms), the results reported here on hexylimidazolium-based POSS further deepen the knowledge of QAS formulations which can be used as antifouling compounds.The reaction of octakis(3-chloropropyl)octasilsesquioxane with four equivalents of 1-hexylimidazole or 1-decylimidazole gave two products labelled as HQ-POSS (hexyl-imidazolium quaternized POSS) and DQ-POSS (decyl-imidazolium quaternized POSS) as regioisomer mixtures. An investigation of the biological activity of these two compounds revealed the higher antimicrobial performances of HQ-POSS against Gram-positive and Gram-negative microorganisms, proving its broad-spectrum activity. Due to its very viscous nature, HQ-POSS was adsorbed in variable amounts on the surface of biologically active oxides to gain advantages regarding the expendability of such formulations from an applicative perspective. Titania and 5 wt% Cu on titania were used as supports. The materials 10HQ-POSS/Ti and 15HQ-POSS/5CuTi strongly inhibited the ability of  The hdesigned .In addition to organic molecules, metal nanoparticles play a role in this field. The antifouling and antimicrobial activity of Cu nanoparticles supported on silica and titania are well-known . The tunHere, two new quaternary ammonium salts based on a POSS cage structure and their preliminary biological evaluation as antimicrobial agents are presented. Then, the most active one was used in conjunction with titania or titania copper-based powders by simple adsorption to obtain an easily manageable powder possessing antimicrobial properties. Biological investigations on these materials are also reported.Octakis(3-chloropropyl)octasilsesquioxane 1  was placed in a vial and dissolved in toluene (150 μL), along with adding 1-hexylimidazole  or 1-decylimidazole . The solution was heated at 90 °C for 19 h and formed, after this time, a very viscous phase. The latter was dissolved in a minimum amount of chloroform by gentle heating and sonication and transferred to a round bottom flask. This procedure was repeated three times and the solvent was removed under reduced pressure to give very viscous compounds .2 material was prepared by the wetness impregnation method of commercial TiO2 oxide (Sigma-Aldrich) with Cu(NO3)2·2.5H2O dissolved in the minimum volume of distilled water. The impregnation of the solid was performed by adding the copper solution to the powder drop-by-drop, by getting it wet but not soaked. The procedure was repeated until all the precursor was added. Then, after drying at 120 °C overnight, the resulting material was labelled as 5CuTi and calcined at 500 °C for 2 h with a heating ramp of 5 °C/min.The 5 wt% Cu/TiO3 solution and stirred (about 600 rpm) until complete dissolution. Subsequently, the amount corresponding to the percentage by weight of 5%Cu/TiO2 was added, and it was left to stir to promote its complete impregnation. After this time, the solution was dried by rotavapor at 40°C. The dry residue thus obtained was recovered and signed . The resulting materials were labeled as xHQ-POSS/5CuTi  and 15HQ-POSS/Ti.Based on the obtained support, a series of HQ-POSS/CuTi samples with loadings ranging from 2 to 30% by weight were prepared, as listed in d signed . As a re2SO4 and HNO3 at 250 °C. The real chemical composition corresponded well to the nominal one with a 5.0 wt% ± 5%.Elemental analysis of the 5CuTi sample was carried out by atomic emission spectroscopy , Italy) after treatment in acidic solution with H2 adsorption–desorption isotherms at −196 °C, using Micromeritics ASAP 2020 equipment through the Brunauer–Emmett–Teller (BET) method in the standard pressure range 0.05–0.3 P/P0. Before the measurements, the samples were degassed at 250 °C for 2 h. By analysis of the desorption curves, using the Barrett–Joyner–Halenda (BJH) calculation method, pore size distributions were also obtained [The specific surface area (SSA) and pore volumes of selected samples were determined from Nobtained . The preX-ray diffraction (XRD) patterns were recorded with a D5000 diffractometer , employing Ni-filtered Cu Kα radiation in the 2θ range between 20° and 80° with a 0.05° step size and time per step of 20 s. The assignment of the crystalline phases was based on the ICSD files. 5TiO2 materials. The precision of the mass loss values was ±0.001 and ±2% of the wt% of HQ-POSS in the samples.The materials’ thermogravimetric analyses (TGAs) were performed in a TGA/DSC1 STAR System from Mettler Toledo Inc. For each analysis, the sample (15 mg) was subjected to a pretreatment in airflow (30 mL/min) from 25 °C to 100 °C with a heating rate of 10 °C/min and a holding time at 100 °C for 30 min, to remove any eventual residual solvent. Then, the temperature was increased from 100 to 1000 °C under airflow (30 mL/min), and the weight loss occurring during this step was considered for calculating the organic weight content of the HQ-POSS-based CuBacillus cereus) and Gram-negative  marine environmental isolates was tested as described elsewhere [−1) of sodium chloride , tryptone (10), and yeast extract (5)) medium and grown for ca. 16 h at 30 °C under shacking conditions (180 rpm). Then, 5 × 105 colony-forming units per milliliter of culture (CFU mL−1) were inoculated in fresh LB medium with increasing concentrations (up to 500 μg mL−1) of HQ- or DQ-POSS. Bacterial cultures were incubated for 24 h as previously described. Afterward, the bacterial cultures’ optical densities at 600 nm (OD600nm) were evaluated using a UV–Vis spectrophotometer .The minimal inhibitory concentration (MIC), i.e., the lowest amount of an antimicrobial compound that visually impairs bacterial growth, of HQ- and DQ-POSS against the Gram-positive  recovery plates, which were incubated at 30 °C under static conditions to allow bacterial colony growth [Pseudomonas PS27 was used as a Gram-negative strain instead of S. maltophilia.Kill curves were carried out to evaluate the minimal bactericidal concentration (MBC), i.e., the lowest concentration of a bactericidal agent able to kill off all microbial cells of a given bacterial species, of HQ and DQ-POSS. Bacterial strains were pre-cultivated and inoculated as previously described in the presence of 1, 2.5, 5, or 7.5 μg mLy growth . The avePseudomonas PS27 biofilm formation, as described elsewhere [Pseudomonas cells were pre-cultivated as described earlier and inoculated at an initial biomass load corresponding to 1 × 107 CFU mL−1. Afterward, the bacterial culture was aliquoted (200 μL) in a 96-well microtiter plate and amended with 250 μg mL−1  of either 10HQ-POSS/Ti or 15HQ-POSS/5CuTi. Thus, bacterial cultures were incubated at 37 °C for 24 h under static conditions to allow bacterial cells to grow as a biofilm. Then, planktonic cells were disposed of and each well was washed 3 times with a sterile saline (NaCl 0.9% w/v) solution to loosely remove adherent cells. Thus, Pseudomonas biofilms were stained (for 15 min at room temperature) using 200 μL of an aqueous solution of crystal violet (0.2% w/v). After staining, excesses of unreacted crystal violet were removed through 5 washing steps with 200 μL of saline solution, with the plate left to dry for 20 min at 65 °C. Crystal violet bound to Pseudomonas cells was solubilized by adding 200 μL of an aqueous solution of acetic acid (30% v/v) and the absorbance of each well was read at 595 nm . Unchallenged Pseudomonas biofilm was used as a reference (positive control) and wells containing uninoculated medium, as a negative control. Thus, the percentage of biofilm formation was calculated as follows:The most promising adsorbed HQ-POSS  were tested to unveil their ability to prevent lsewhere . PseudomAll the experiments were performed at least in triplicate and data are reported as the average value (n = 3) with standard deviations.All reagents were purchased from Merck Life Science S.r.l. . 2 was employed as desolvation gas at 300 °C and a flow rate of 8 L/min. The nebulizer was set to 45 psig. The sheath gas temperature was set at 350 °C and a flow of 12 L/min. A potential of 3.2 kV was used on the capillary for the positive ion mode. The fragmentor was set to 175 V. MS spectra were recorded in the 150–3200 m/z range. Mass spectrum data were analyzed by using the software MassHunter Qualitative Analysis B.06.00 , Italy).HPLC/MS analysis was performed by adapting previously reported methods ,26. SampBased on the antimicrobial activity of 1,3-disubstituted imidazolium salts and considering the usefulness of the POSS cage and the biological activity of quaternized POSS molecules, the possibility of easily synthesizing new alkylimidazolium-POSS salts to investigate their antimicrobial activity was envisioned. Then, due to the high polar nature of such imidazolium-POSS salts and to obtain powders easily manageable and mixable with the proper paint, the obtained salts were adsorbed on the surface of materials suitable for this purpose. 1 by its reaction with four equivalents of 1-hexylimidazole or 1-decylimidazole  and DQ-POSS (decyl-imidazolium quaternized POSS). Tetra-substitution can give a mixture of inseparable regioisomers that were used as obtained.The synthesis started with octakis(3-chloropropyl)octasilsesquioxane midazole . The use1H NMR spectrum of HQ-POSS was in accordance with the proposed structure (2Cl) resonate at 3.52 ppm and protons H-2′ could be assigned to the shoulder at ca. 1.99 ppm, whereas protons H2′ and H-5 could relate to the signal at 1.86 ppm. The signal at 1.22 ppm could be assigned to H-2, H-3, and H-4 protons, the signal at 0.85 ppm, to H-1, and the signal at 0.76, to methylene groups linked to silicon (H-9 and H-3′). Considering the signals of H-6 and H-7 protons and the signal of H-2′, it was possible to estimate a ca. 1:1 ratio between chloropropyl and 1-hexyl-3-propyl-1H-imidazol-3-ium chains that was in agreement with a tetra-substituted POSS. This NMR pattern included the presence of possible regioisomers and did not exclude the possible presence of mono-, di-, and tri-substituted POSSs. The 1H NMR spectrum of DQ-POSS  compared to DQ-POSS, which exhibited an impairment of bacterial growth at a concentration as high as 500 μg mL−1.The next step investigated the antimicrobial activity of HQ-POSS and DQ-POSS. The quaternized HQ- and DQ-POSS exhibited different antimicrobial activity against the Gram-negative and -positive marine bacteria ectively . The ant−1) due to the challenge exerted by quaternized POSSs underlines the far greater proficiency of HQ-POSS in inhibiting bacterial growth (−1) was sufficient to carry out a 100% killing effect—corresponding to the MBC value—toward Gram-negative bacterial cells within the 24 h challenge  only determined a slight decrease in CFU evaluated . Firstly, from the comparison between commercial TiO2 oxide, as received, with the material after calcination, the latter resulted in a lowering of the SSA values along with pore volumes, while pore sizes increased. Such findings agree with the shrinkage of the external surface and porosity of titania as a consequence of the calcination process, which likely causes the removal of the structural water and surface OH groups, the collapse of the smallest pores, and a shift of the mean pore size distribution toward higher values. A similar trend arises by comparing the properties of 5CuTi with the parent TiO2. Indeed, the 5CuTi sample was characterized by an SSA of 52.8 m2/g vs. 82 m2/g for the titania, the mean pore size shifted toward higher values, and the pore volume decreased. The reported data suggest that after copper nitrate impregnation over titania and further calcination, the CuO nanoparticles formed may have partially covered the external surface of the support and blocked some pores. Accordingly, XRD patterns registered on the 5CuTi sample revealed crystalline peaks assigned to the CuO phase along with the typical features of titania, as anatase and rutile, which were confirmed by cross-referencing it with ICSD files  as its only sources of carbon and energy, which concomitantly stimulate its biotic accumulation of the toxic xenobiotic compound perfluorohexane sulfonate [To further prove the suitability of such formulations in inhibiting bacterial cell proliferation, the Gram-negative microbe tested, in this case, was ulfonate .−1 (15HQ-POSS/5CuTi) or 100 μg mL−1 of (10HQ-POSS/5CuTi or 10HQ-POSS/Ti)—corresponding to the MBC values—was sufficient to completely kill B. cereus cells within the 24 h challenge  or 8 (15HQ-POSS/5CuTi and 10HQ-POSS/Ti) logarithmic units . However, in the case of Pseudomonas PS27, MBC values for the most active formulations were not found. This aspect corroborates the good adaptability of this environmental isolate to organic xenobiotics that, similarly to QASs, can compromise bacterial cell membrane fluidity and functionality, leading to cell death [As a result, 10HQ-POSS/5CuTi, 15HQ-POSS/5CuTi, and 10HQ-POSS/Ti are the formulations that most affected bacterial survival , althoughallenge b. The 10ic units a. The enll death ,36. Thesll death ,38. The ll death  successfPseudomonas species are of extreme concern for such a matter since they are proficient biofilm producers, opportunistic pathogens for immunocompromised humans, as well as the cause of spoilage in aquatic environments [per se, their functionalization with QASs can lead to efficient antifouling agents. The killing effect would rely on the cationic nature  of QAS and the amphiphilic character of its chain. These chemistry features allow QASs to interact, with a high affinity, with the bacterial cell membrane [Pseudomonas PS27 cells to grow and develop as a biofilm (−1) that greatly impaired Pseudomonas PS27 planktonic growth octasilsesquioxane and four equivalents of 1-hexylimidazole or 1-decylimidazole. The use of four equivalents of imidazole compounds was dictated by the fact that an extensive quaternization may feature derived compounds with low antimicrobial potential. HQ-POSS (hexyl-imidazolium quaternized POSS) showed excellent antimicrobial activity toward Gram-positive and Gram-negative microorganisms, compared to DQ-POSS (decyl-imidazolium quaternized POSS). The absence of antimicrobial activity by the latter compound could be ascribed to agglomeration phenomena occurring between the alkyl chains of QASs via ionic and van der Waals interactions. Thus, the best working formulation, HQ-POSS, was adsorbed in different amounts onto the surface of titania and 5 wt% copper/titania for an applicative perspective. Two of these materials  strongly inhibited the ability of


We obtain several characterizations for these two concepts. We show that soft c-continuity and soft almost c-continuity are preserved under soft restrictions. In addition, we investigate the conditions under which the composition of two soft c-continuous and soft almost c-continuous functions is soft c-continuous and soft almost c-continuous. Moreover, via soft We present the notions of soft  It was suggested that scenarios such as fuzzy sets and soft sets be used to deal with these types of problems. The concept of “soft sets” was first proposed by Molodtsov The soft sets have been used by numerous academics and researchers who are interested in uncertainty in both theoretical and applied concerns. In order to solve decision-making issues, Maji et al. In order to build a soft topology over a specified set of parameters, Shabir and Naz Soft topology and other fields of mathematics have seen extensive research on the soft continuity. The importance of soft continuity lies in the majority of its applications in soft topological models, data modeling, engineering, science, economics, and business, among others, make it an important topic that has received a lot of attention from many scientists.c-continuity and soft almost c-continuity which are weaker forms of soft continuity and soft almost continuity, respectively. We obtain several characterizations for these two concepts. We show that soft c-continuity and soft almost c-continuity are preserved under soft restrictions. In addition, we investigate the conditions under which the composition of two soft c-continuous and soft almost c-continuous functions is soft c-continuous and soft almost c-continuous. Moreover, via soft In this paper, we introduce the concepts of soft Topological space and soft topological space  will be employed concurrently in the present research. The notions and terminology from W in W in K in K in Let Now we will review some of the notions that will be used in the continuation of the paper.Definition 1.1W is said to be a regular open set in Definition 1.2Let p is called almost continuous at l if for any p is called almost continuous if p is almost continuous at each point (1) p is called c-continuous at l if for any p is called c-continuous if p is c-continuous at each point (2) p is called almost c-continuous at l if for any p is called almost c-continuous if p is almost c-continuous at each point (3) Definition 1.3A soft set (1) (2) (3) Definition 1.4H  M is said to be a soft regular open set in (b) (c) Definition 1.6G is called a finite soft set if for all Definition 1.7H is called soft For a given STS Theorem 1.8For any TS, the familyis a soft topology on L relative to F. This soft topology will be denoted by.Theorem 1.9For any collection of TSs, the familyis denoted byand forms a soft topology on L relative to F.Definition 1.10(a) (b) 2c-continuity as a novel category of soft functions and investigate some of its features. We characterize it in different ways and show that this category of soft functions strictly contains the category of soft continuous functions. We show that soft c-continuity is preserved under soft restrictions. In addition, we investigate the conditions under which the composite of two soft c-continuous functions is soft c-continuous. Furthermore, we characterize the soft compactness of soft topological spaces over finite sets of parameters using soft We propose soft Definition 2.1Let c-continuous at (a) c-continuous if c-continuous at all members of (b) Theorem 2.2The following are equivalent for the soft function:(a)is soft c-continuous.(b) For everysuch that,.(c) For every,.Proofc-continuous at (a) ⟶ (b): Let (b) ⟶ (c): Let c-continuous. □(c) ⟶ (a): Let Corollary 2.3Letbe a soft function such thatis soft Hausdorff. Then the following are equivalent:(a)is soft c-continuous.(b) For everysuch that,.(c) For every,.ProofFollows from Theorem 4.9 of Lemma 2.4Letbe STS,, andbe soft base for. Then the following are equivalent:(a).(b) For eachsuch that, there exists a finite subcollectionsuch that.Proof(a) ⟹ (b): It is clear.S(b) ⟹ (a): Let Theorem 2.5Letbe a STS such that A is finite and let. Thenif and only if.ProofNecessity. Suppose that T= Sufficiency. It is clear. □Corollary 2.6Letbe a STS such that A is finite. Thenis soft compact if and only ifis soft compact.Theorem 2.7Letbe a collection of TSs such that A is finite. Thenif and only iffor all.ProofNecessity. Let Sufficiency. Let Corollary 2.8Letbe a TS and let A be any finite set. Thenif and only iffor all.ProofFor each Theorem 2.9Letandbe two families of TSs such that A and F are finite. Letandbe functions with u being bijective. Thenis soft c-continuous if and only ifis c-continuous for all.ProofNecessity. Let c-continuous. Let c-continuous, then c-continuous.Sufficiency. Let c-continuous for all c-continuous for all c-continuous. □Corollary 2.10Letandbe functions where u is a bijection between finite sets. Thenis c-continuous if and only ifis soft c-continuous.ProofFor each Theorem 2.11Soft continuity implies soft c-continuity.Proofc-continuous. □Let Example 2.12ς be the usual topology on L. Define Let c-continuous but not continuous. Therefore, by c-continuous, it is not soft continuous.It is proved in Example 2 of The condition ‘soft Hausdorff’ in Example 2.13δ the topology on L having c-continuous. Since Let Theorem 2.14Ifis soft c-continuous, then for any subsetthe soft restrictionis soft c-continuous.Proofc-continuous and let c-continuous. □Suppose that Theorem 2.15Ifis soft continuous andis soft c-continuous, thenis soft c-continuous.Proofc-continuous, then c-continuous. □Let c-continuous and c-continuous:The following example illustrates that if Example 2.16ς be the usual topology on L. Define c-continuous, c-continuous. Therefore, by c-continuous and c-continuous.Let Theorem 2.17Letbe surjective and soft open. Thenis soft c-continuous ifis soft c-continuous.Proofc-continuous, then c-continuous. □Let Theorem 2.18Letandbe STSs and letsuch thatand. Ifis a soft function such that the soft restrictionsandare soft c-continuous, thenis soft c-continuous.Proofc-continuous. □Let Theorem 2.19Letandbe STSs and letsuch thatand. Ifis a soft function such that the soft restrictionsandare soft c-continuous, thenis soft c-continuous.ProofLet Case 1.c-continuous at Thus, we have Case 2.c-continuous at Case 3.c-continuous at Theorem 2.20Letandbe STSs and letsuch that. Ifis a soft function such that the soft restrictionsandare soft c-continuous at, thenis soft c-continuous at.Proofc-continuous at Let c-continuous at It follows that Theorem 2.21Letbe a STS,a Hausdorff STSs, anda soft c-continuous function. Ifis a soft compact subset of, thenis soft continuous.Proofc-continuous, then Let 3c-continuous functions is precisely between the classes of soft c-continuous and soft almost continuous functions. Also, we show that soft almost c-continuity is preserved under soft restrictions. Furthermore, we investigate the conditions under which the composite of two soft almost c-continuous functions is soft almost c-continuous. In addition, we investigate the connections between this family of soft functions and their general topological analogs.We introduce soft almost c-continuity as a new type of soft function and investigate some of its features. We give several characterizations of it. We demonstrate with the help of examples that the class of soft almost Definition 3.1Let c-continuous at (a) c-continuous if c-continuous at each soft point (b) Theorem 3.2The following are equivalent for the soft function:(a)is soft almost c-continuous.(b) For everysuch that,.(c) For every,.(d) For eachand eachsuch thatand, we findsuch thatand.(e) For eachand eachsuch thatand,.Proofc-continuous at (a) ⟶ (b): Let (b) ⟶ (c): Let (c) ⟶ (d): Let (d) ⟶ (e): Let M= (e) ⟶ (a): Let Theorem 3.3Letandbe two families of TSs such that A and F are finite sets. Letbe a function andbe a bijective function. Thenis soft almost continuous if and only ifis almost continuous for every.ProofNecessity. Suppose that Sufficiency. Suppose that Corollary 3.4Letandbe functions where u is a bijection between finite sets. Thenis almost continuous if and only ifis soft almost continuous.ProofFor each Theorem 3.5Letandbe two families of TSs such that A and F are finite sets. Letandbe functions with u is bijective. Thenis soft almost c-continuous if and only ifis almost c-continuous for every.ProofNecessity. Let c-continuous. Let c-continuous, then by c-continuous.Sufficiency. Let c-continuous for all c-continuous for all c-continuous. □Corollary 3.6Letandbe functions where u is a bijection between finite sets. Thenis almost c-continuous if and only ifis soft almost c-continuous.ProofFor each Theorem 3.7Soft c-continuity implies soft almost c-continuity.Proofc-continuous and let c-continuous, then c-continuous. □Let Theorem 3.8Soft almost continuous functions are soft almost c-continuous.Proofc-continuous. □Let The converses of Example 3.9ς be the usual topology on L, and δ be the topology on N having c-continuous, but it is almost c-continuous. Therefore, by c-continuous, but it is soft almost c-continuous.Let Theorem 3.10Ifis soft almost c-continuous, then for any subsetthe soft restrictionis soft almost c-continuous.Proofc-continuous and let c-continuous. □Suppose that Theorem 3.11Ifis soft continuous andis soft almost c-continuous, thenis soft almost c-continuous.Proofc-continuous, then c-continuous. □Let Theorem 3.12Letbe surjective and soft open. Thenis soft almost c-continuous ifis soft almost c-continuous.Proofc-continuous, then c-continuous. □Let Theorem 3.13Letbe a soft function and. If for somewe haveandis soft almost c-continuous at, thenis soft almost c-continuous at.Proofc-continuous at c-continuous at Let Theorem 3.14Letbe a soft function. Ifsuch thatandis soft almost c-continuous for every, thenis soft almost c-continuous.Proofc-continuous, then by c-continuous at c-continuous. □Let Theorem 3.15Letandbe STSs and letsuch thatand. Ifis a soft function such that the soft restrictionsandare soft almost c-continuous, thenis soft almost c-continuous.ProofLet Case 1.c-continuous at Thus, we have Case 2.c-continuous at Case 3.c-continuous at Theorem 3.16Letandbe STSs and letsuch that. Ifis a soft function such that the soft restrictionsandare soft almost c-continuous at, thenis soft almost c-continuous at.Proofc-continuous at Let c-continuous at It follows that Theorem 3.17Letbe a STS,a soft Hausdorff STSs, anda soft almost c-continuous function. Ifis a soft compact subset of, thenis almost continuous.Proofc-continuous, then there exists Let 4In this section, we show that for a given soft topological space Theorem 4.1Letbe a STS and. Thenforms a soft base for some soft topology on R relative to A.ProofR relative to A. □Since R relative to A having For any STS Theorem 4.2For any STS,is soft compact.ProofLet Theorem 4.3Ifis a soft compact Hausdorff STS, thenis soft Hausdorff and.ProofLet Theorem 4.4Ifis a STS such thatis soft Hausdorff, thenis soft compact and.ProofWe may assume that there exist Corollary 4.5A STSis soft compact Hausdorff if and only ifis soft compact Hausdorff.ProofFollows directly from Theorem 4.6Ifis soft almost c-continuous andis soft Hausdorff, thenis soft continuous.Proofc-continuous, then by Since 5Since Molodtsov c-continuity and almost c-continuity to include soft topological spaces. We introduce several characterizations, relationships, and counter-examples regarding them.In the first goal of the present paper, we extended the concepts of In the second goal of this paper, we introduce and investigate the soft topology having soft regular open sets with soft compact complements as a new soft topology coarser than the original soft topology. We studied the relationship between our creative concepts in soft topological spaces and their topologically analogous conceptions.c-continuity; 2) To investigate the soft product of soft c-continuity and soft almost c-continuity.Future research might look into the following topics: 1) To investigate some weaker forms of soft Samer Al Ghour: conceived and designed the experiments; performed the experiments; analyzed and interpreted the data; contributed reagents, materials, analysis tools or data; wrote the paper.The authors declare no conflict of interest.


To date, epidemiological studies have not evaluated heroin-related deaths in the Middle East and North African regions, especially Saudi Arabia. All heroin-related postmortem cases reported at the Jeddah Poison Control Center (JPCC) over a 10-year period (21 January 2008 to 31 July 2018) were reviewed. In addition, liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was utilized to determine the 6-monoacetylmorphine (6-MAM), 6-acetylcodeine (6-AC), morphine (MOR), and codeine contents in unhydrolyzed postmortem specimens. Ninety-seven heroin-related deaths were assessed in this study, and they represented 2% of the total postmortem cases at the JPCC . In the blood, urine, vitreous humor, and bile samples, the median morphine concentrations were 280 ng/mL, 1400 ng/mL, 90 ng/mL, and 2200 ng/mL, respectively; 6-MAM was detected in 60%, 100%, 99%, and 59% of the samples, respectively; and 6-AC was detected in 24%, 68%, 50%, and 30% of the samples, respectively. The highest number of deaths  was observed in the 21–30 age group. In addition, 61% of cases were classified as “rapid deaths,” while 24% were classified as “delayed deaths.” The majority (76%) of deaths were accidental; 7% were from suicide; 5% were from homicide; and 11% were undetermined. This is the first epidemiological study to investigate heroin-related fatalities in Saudi Arabia and the Middle East and North African region. The rate of heroin-related deaths in Jeddah remained stable but increased slightly at the end of the study period. Most patients were heroin-dependent abusers and from the middle-aged group. The availability of urine, vitreous humor, and bile specimens provided valuable information regarding the opioids that were administered and the survival time following heroin injection. The abuse of heroin  remains a major cause of death worldwide. For example, an estimated 62 million people used opioids for non-medical purposes in 2019 , with half using heroin or opium ,4, whileIn the Middle East and North African (MENA) region, principally in the Arabian Gulf region, heroin is reported in the media as a symbol of drug addiction. However, heroin-related fatalities have rarely been reported in scientific literature from this region. Thus, little is known about heroin-related deaths, and most studies in the Arabian Gulf region are outdated ,9. Al-MaIn Saudi Arabia, alcohol and drug use are prohibited by law and denounced based on social and religious perspectives ,12. ThusHeroin is unstable in biological specimens and rarely identified in postmortem cases . AlternaThe patterns of heroin-related deaths are poorly understood in the MENA region. Thus, up-to-date epidemiological studies to reveal heroin-related fatalities and explore the problem of heroin abuse are a crucial task. As Jeddah is one of the major cities in Saudi Arabia (4 million population), this paper reports the first epidemiological study evaluating heroin-related deaths in Jeddah City, Saudi Arabia, between 2008 and 2018 and investigates whether metabolites of heroin found in various bodily fluid samples can be used to identify the type of opioid ingested and the time of death after administration. Such toxicological information is crucial for providing knowledge on the trends in illegal drug use and planning initiatives to reduce accidents and deaths among drug users.® solid phase extraction (SPE) cartridges (CSDAU203) were obtained from United Chemical Technologies .Morphine, morphine-d3, 6-MAM, 6-monoacetylmorphine-d3 (6-MAM-d3), codeine, codeine-d3, and 6-AC were purchased from Lipomed . Methanol (HPLC grade), acetonitrile (HPLC grade), ammonium carbonate, formic acid, and ammonium hydroxide were obtained from BDH . Ammonium formate was obtained from Sigma-Aldrich . Clean Screen2O), and 2 mL of 0.1 M phosphate buffer adjusted to pH 6. The sample mixture was then loaded onto the SPE column using gravity. Next, the cartridges were washed by adding 1 mL of D.H2O, followed by 1 mL of acetic acid (0.1 M), and then dried under vacuum for 5 min. The third washing step was completed by adding 2 mL of hexane. Two elution steps were performed: the first elution (A) was performed by adding 2 mL hexane/ethyl acetate . Next, the elution tubes were removed, and the SPE cartridges were washed using 3 mL of methanol and then dried under full vacuum for 2 min. The second elution (B) was performed by adding 3 mL of dichloromethane/isopropanol/ammonium hydroxide  to each cartridge. Both fractions were collected in a glass evaporation tube and evaporated to dryness using nitrogen. Finally, 200 μL of the initial mobile phase was added to the final extracts and subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS) using an injection volume of 1.0 μL.One milliliter of each specimen was placed in a glass test tube, which was then spiked with 50 µL of the internal standard . The mixture was then mixed and vortexed for at least 10 s. Next, 2 mL of 0.1 M phosphate buffer (pH 6) was added to the samples, mixed, and centrifuged for 10 min at 3500 rpm. Before loading the samples into the SPE cartridges, the samples were prepared for SPE by adding 2 mL of methanol, 2 mL of deionized water  equipped with electrospray ionization (ESI+) and selective reaction monitoring modes. Analytes were separated using a Synergy Polar RP column  equipped with a guard column with identical packing material . The column oven and auto-sampler tray temperatures were kept at 30 °C and 4 °C, respectively. The gradient mobile phase consisted of ammonium formate buffer  as mobile phase A and an organic modifier of 100% acetonitrile as mobile phase B, with a flow rate of 0.3 mL/min for the whole run. The gradient program was initiated by applying 3% B for 3 min, which was increased to 15% over the next 5 min, 26% over the next 7 min, 80% over the next 13 min, and 95% over the next two min. After 27 min, the initial mobile phase was applied for 3 min. Data were acquired and managed using the Xcalibur system .The second LC-MS/MS analysis was performed according to a previously reported method . Brifly,This study was approved by the IRB committee of Jeddah Health Affairs, Ministry of Health, Jeddah, Saudi Arabia .Blood samples were collected from the subclavian site in tubes containing 1% sodium fluoride (BNaF). Vitreous humor fluid was collected in gray tubes containing sodium fluoride, and urine and bile samples were stored in a plain container without any preservative. All samples were stored frozen (at −20 °C) until analysis. Autopsy samples were thawed to obtain them and refrozen until use. Blood samples were obtained for 84 postmortem cases (87%), urine samples were obtained for 74 cases (76%), vitreous humor samples were obtained from two eyes in 70 cases (72%), and bile specimens were obtained for 27 cases (28%).All postmortem body fluids and tissues collected for forensic toxicology investigations are analyzed for commonly abused drugs and reported, and they are also assessed based on requests by forensic pathologists. All heroin-related postmortem cases reported at the Jeddah Poison Control and Medical Chemistry Center (JPCC) over the last 10-years (21 January 2008 to 31 July 2018) were reviewed. The 6-MAM, 6-AC, morphine, and codeine contents were reviewed, and case details were collected from the online Forensic Toxicology Jeddah Reports Database. The search was conducted between February 2015 and July 2018. Data before February 2015 was manually collected from JPCC archive files. Cases positive for heroin use were reviewed and included in this investigation according to the inclusion/exclusion criteria mentioned below. Ninety-seven cases reported during the study period were included.The same criteria applied in our previous study were used in the current study . The mosAll postmortem cases, irrespective of the manner of death, were screened using a common immunoassay reagent. The second step was to search for other concomitant drugs using general unknown screening approaches (GUS),  by gas chromatography (GC) coupled to a flame ionization detector (FID), gas chromatography coupled to mass spectrometry (GC-MS), and LC-MS/MS.The analysis methods were all fully validated using international guidelines for forensic investigation , and a sp-value <0.05 was considered statistically significant.Useful statistical data are reported in terms of the frequency, percentage, mean, median, and range when applicable. The data were calculated using Statistical Packages for Software Sciences (SPSS) version 28.0.1.1  and Microsoft Excel version 16.66.1 . Descriptive statistics were completed, and continuous data were presented as median, minimum, and maximum. Definite data were displayed as frequency and percentage. A Mann-Whitney U test was employed to estimate variations between groups. Spearman’s correlation test (R) was utilized to compare variables. A The method in the current investigation was validated according to ANSI/ASB standards  and otheHeroin biomarkers are not stable, which leads to a decrease in the concentration of these biomarkers in tested specimens that are not stored properly; therefore, a sensitive method is required to measure these biomarkers. The stability of these heroin biomarkers is a well-known issue that must be considered during sample processing, namely, during sample storage, preparation, and analysis in an autosampler. Therefore, all specimens were immediately frozen, thawed before extraction, and then immediately refrozen after sampling. The stability of these heroin biomarkers was investigated in an autosampler using three controls that were previously used in precision studies, and they were reanalyzed after 24 h, 48 h, and one week.The most important feature of such analysis methods is to investigate the limit of detection (LOD) in the proposed matrix of interest and the workable lower limit of quantification (LOQ) that can be utilized to quantify these unstable analytes at very low concentrations (≤1 ng/mL). Elevated morphine concentrations in urine and bile were used as the upper limit of quantification (ULOQ) and assessed for all heroin-related analytes. The sensitivity analysis was performed in accordance with the ANSI/ASB method validation guidelines .In each batch of samples, negative blank samples from different matrices were included without any standards or internal standards. Negative blank samples with internal standards were only used to investigate method selectivity, and negative blank samples were run following the calibrator with the highest concentration to investigate any carryover. Matrix effects were investigated using post-extraction addition as reported by Matuszewski et al. . Six difThe validated analysis method was acceptable , and theLinearity was accepted, with coefficients of determination greater than 0.99 for 6-MAM, 6-AC, morphine, and codeine in multiple body fluid samples. The LOD values were estimated from ten different calibration curves and ranged between 0.2 and 0.4 ng/g, while the LOQ was evaluated by spiking with 1 ng/mL of each analyte of interest, and the results were calculated using freshly prepared calibration curves for all analytes of interest in different matrices of interest. The precision, accuracy, dilution, and autosampler stability results were all within 15% of the nominal value, thus confirming that the method is suitable for the quantification of target analytes in the matrices of interest. In addition, carryover contamination from the previous positive control test was not detected.n = 85; range, 23–4400 ng/mL); the highest median BNaF morphine concentration occurred in 2012 (470 ng/mL), while the lowest median concentration occurred in 2008 (141 ng/mL).The number of heroin-related deaths in the city of Jeddah within the study period represents 2% of the total number of postmortem cases received by the JPCC between 2008 and 2018 . AlthougThe mean age of the patients was 38 ± 12 years . The 21–30 age group had the highest number of deaths, with almost 33% of the total cases (n = 32 cases), followed by the 31–40 age group , while the 10–20 age group had the lowest number of heroin-related death cases , which led to the identification of both heroin biomarkers when the blood was fresh and putrefaction was not observed. The median concentrations of 6-MAM and 6-AC in cases with a PMI within 24 h were 16 and 2 ng/mL, 22 and 3 ng/mL, 324 and 35 ng/mL, and 12 and 4 ng/mL in the BNaF, vitreous humor, urine, and bile samples, respectively . 6-AC waIn the current study, both biomarkers were detected in the vitreous humor in two cases with a PMI longer than 10 days, whereas 6-MAM was negative in the BNaF samples, which indicates that the role of PMIs on heroin biomarkers can be minimized if samples are stored correctly following autopsy and if the vitreous humor is the sample of choice for heroin-related fatality investigations. In the current study, heroin alone contributed to death in 68% of the studied cases, whereas intoxication with other co-ingested substances contributed to 32% . A higheThese findings indicate that the morphine concentration in heroin-related fatalities showing the presence of other CNS drugs is often lower than that in heroin-alone cases. The significant role of the PMI in cases of heroin metabolites is well known, and the tolerance and health status of the deceased contribute to this finding. Similar trends were observed among the various specimens, with slightly higher median concentrations in the urine and bile. Moreover, a polydrug intoxication case showed a slightly higher morphine concentration in the vitreous humor than that with heroin alone.The most frequently detected drugs, regardless of the cause of death, were methamphetamine, cannabis, amphetamine, alprazolam, cocaine, and ethanol. Thirty-eight cases only showed heroin metabolites. A higher median morphine concentration was measured in only heroin cases compared to those in which heroin was the sole cause of death despite the presence of another drug, such as amphetamine or cannabis (370 ng/mL vs. 310 ng/mL). Similarly, the median morphine concentration (312 ng/mL) decreased when one extra drug was used, and it was further decreased (191 and 198 ng/mL) when two and four extra drugs were co-ingested, respectively.Notably, methamphetamine was co-ingested with heroin in twenty-three cases . The median morphine concentration for most co-ingested drugs was often higher than 200 ng/mL. A reduction in the median morphine concentration  occurred when heroin was used in combination with cocaine.In this study, 61% and 24% of the cases were rapid and delayed deaths, respectively, and 15% had an undetermined time of death. This was either because of a lack of information caused by the deceased dying without a witness or because the bodies were moved after death to a deserted area where the bodies began to decompose and thus did not show signs of heroin use, such as injection marks . In thesThis suggests that either the undetermined cases died immediately after heroin was administered and the environmental surroundings allowed for the hydrolysis of 6-MAM to morphine or that a delayed death occurred, which allowed morphine glucuronide to deconjugate to free morphine due to the long PMI before sampling. In contrast, lower median morphine concentrations were observed in the delayed death group (median BNaF = 210 ng/mL) than the rapid death group.In all groups, the median morphine concentration was much lower in the vitreous humor than the blood. This indicates that some of the heroin biomarkers were converted to their metabolites in the blood but were stable in the vitreous humor after death. Nevertheless, the vitreous humor results should be interpreted with caution because a certain amount of morphine is associated with accumulation from the use of old doses by chronic heroin users. Interestingly, 6-MAM levels were higher for the rapid death cases (36 ng/mL) than the delayed death cases (14 ng/mL) and undetermined death cases (7 ng/mL). This can be explained by many factors, including the longer PMI in delayed deaths, putrefaction effects, and body storage effects, especially when the time of death is unknown. These conditions led to a decrease in the 6-MAM concentration in the vitreous humor. This highlights the importance of testing the vitreous humor in cases of longer PMIs and negative 6-MAM in the blood.Morphine levels in bile were primarily detected in chronic heroin users, which limits the use of these values in distinguishing between rapid and delayed deaths. 6-MAM in bile was detected in 10 of 17 rapid deaths, 3 of 6 delayed deaths, and not detected of 4 undermined cases. Urine is most likely to be positive for heroin biomarkers and their metabolites in these types of deaths. In this study, the free morphine concentration was high for rapid deaths (2100 ng/mL) compared to that for delayed deaths (1300 ng/mL) and undetermined cases (550 ng/mL). An almost 4-fold higher median concentration of 6-AC in urine was observed for rapid death (40 ng/mL) compared with delayed death (10 ng/mL). Moreover, the median codeine concentration was higher in the unknown group (30 ng/mL) than in the rapid (20 ng/mL) and delayed groups (10 ng/mL). Codeine forms quickly after heroin ingestion as a product of 6-AC degradation. Most codeine is metabolized to codeine-6-glucuronide, while some is metabolized to morphine.In the current study, 76% of the total cases were ascribed to accidental death, and they had a median age, median BNaF morphine concentration, and PMI of 38 years, 280 ng/mL, and 24 h, respectively. Nevertheless, most heroin abusers in Saudi Arabia used drugs in private or remote areas, such as deserted areas and open land outside the city. In the case of overdoses, deceased bodies left behind without witnesses complicated the identification of the mode of death, especially if the bodies were heavily putrefied.Information about intentional overdoses was available for seven heroin-related fatalities. Four of these individuals died at home, and two died outdoors while accompanied by a friend. These cases had a median BNaF morphine concentration of 480 ng/mL, a PMI of 24 h, and an age of 48. The highest levels of vitreous humor and morphine were detected in suicide cases (150 ng/m).In five cases, the mode of death was identified as homicide, and they presented a median BNaF morphine concentration of 180 ng/mL, a PMI of 24 h, and an age of 22. Notably, most cases were discovered outdoors.The data in Most heroin deaths occurred in outdoor environments (63%), with a median PMI of 48 h, whereas 37% of the patients died in a private home , with a It has been mentioned that the weather in Saudi Arabia is extremely hot most of the year, and the weather in Jeddah is known to be highly humid. Accordingly, it is well-known that putrefaction and postmortem changes would begin a few hours following death if bodies were not stored appropriately ,33. In cIn 63 out of 97 cases (65%), police and forensic pathologist reports indicated that no witnesses observed the final moments before death . Nine paIn this study, higher BNaF morphine concentrations were measured in patients whose deaths were pronounced at hospitals , followed by those found in the street , under bridges , in cars , in rental flats or hotel rooms , and in deserted areas . PMI, environmental conditions (location of death and weather), and patient tolerance have major effects on the detection of heroin biomarkers and metabolites. The patients who died at the hospital had a lower PMI, and their deaths were caused by an overdose of heroin alone. In contrast, among individuals who died under bridges, most cases showed putrefaction, and 6 out of 10 cases were polydrug intoxication cases. Notably, a high number of deaths occurred in cars, with 13 out of 17 cases of polydrug intoxication having a relatively low PMI (median 24 h) and 6 cases exhibiting signs of putrefaction, with two heavily putrefied. Vitreous humor and urine were available in 13 and 12 of these cases, respectively, and 6-MAM and 6-AC were detected in 6 and 9 cases, respectively. Only one case was positive for both heroin biomarkers in bile. A higher median of BNaF morphine was observed compared to vitreous humor (60 ng/mL), which suggested a shorter survival time. This was supported by the lower urine morphine concentration (860 ng/mL) and highest bile morphine concentration (9800 ng/mL), suggesting a chronic heroin user.Twenty-one cases showed signs of putrefaction , 60% shoThe seasonal distribution of heroin-related fatalities is presented in The median morphine concentrations in the BNaF, urine, vitreous humor, and bile samples were 280, 1400, 90, and 2200 ng/mL, respectively. Among the available BNaF, urine, vitreous humor, and bile specimens, 6-MAM was detected in 60%, 100%, 99%, and 59%, while 6-AC was detected in 24%, 68%, 50%, and 30%, respectively. The presence of sodium fluoride in the blood test tube as a preservative prevented 6-MAM from converting to morphine in most cases. Additionally, the availability of urine, bile, and vitreous humor samples provides valuable information on the opioids that have been administered. The median free morphine concentration ratios among the vitreous humor/BNaF, urine/BNaF, and bile/BNaF were 0.37-fold (n = 63), 5.6-fold (n = 64), and 7.3-fold (n = 23), respectively. In addition, free morphine/free codeine were always higher than 1, with median ratios of 13-fold (n = 84), 13-fold (n = 70), 6-fold (n = 68), and 85-fold (n = 25) for BNaF, urine, vitreous humor, and bile, respectively.p-values higher than 0.5). The correlation between the 6-AC concentration obtained from multiple biological fluids was always poor and not statistically significant, and it was not calculated for bile due to the lack of positive samples. A negative correlation was observed between 6-AC and morphine in bile and analytes of interest in the BNaF, urine, and vitreous humor samples, as shown in The Spearman correlation coefficient (R) was used to establish the relationship between heroin biomarkers, morphine, and codeine concentrations in various body fluids . 6-MAM iGood correlations were obtained between the analytes of interest detected in BNaF vs. vitreous humor, BNAF vs. urine, and vitreous humor vs. urine. The level of 6-AC seemed to be higher in the vitreous humor than the blood, which can directly reflect the anatomical location of the vitreous humor; thus, 6-AC in the vitreous humor is more stable and has a longer half-life before conversion to codeine than that in blood samples.The bile samples showed the lowest positive results for 6-AC (eight cases) compared to 6-MAM. The 6-MAM was detected in 16 of the 27 bile samples tested in this study. Although the correlation between heroin-related compounds in BNaF and bile was weak, the correlation between these analytes in bile and their corresponding specimens in vitreous humor and urine was strong, except for the 6-AC concentration.In the literature, few studies have detailed the relationship between addiction and morphine concentration. Steentoft et al. reported 245 heroin-related deaths, and all of these cases were from known heroin abusers with the exception of 13 cases . ElfawalHeroin users often die young because of polydrug intoxication , and mosp > 0.05) [Jones and Ahlner studied 766 postmortem heroin-related deaths and 124 traffic antemortem cases related to heroin use and found no correlation between the concentration of free morphine and the age of heroin users  . It is bThe level of codeine was low in all age groups , which could be explained by the fact that 6-AC is metabolized to codeine and codeine-6-glucuronide (C6G) faster than to other compounds. A recently published study demonstrated that C6G was not detected in blood samples obtained from authentic postmortem cases following heroin intake, while codeine was . In anotSkopp concluded that the PMI competes with the postmortem redistribution phenomenon (PMR) , and theFugelstad et al. studied the effects of postmortem changes on heroin-related fatalities and concluded that the concentration detected at autopsy was the same as that at the time of death . In contPMR has been debated scientifically, especially for postmortem blood morphine concentrations following heroin-related deaths. Maskell et al. suggested the use of vitreous fluid to verify heroin use because minimal morphine change was detected in their study . An incrThe use of blood-free morphine/total morphine ratios in the blood to identify the cause and mode of death has been reported ,42. HoweJones and Ahlner found no differences in the median blood morphine concentration between intoxication with polydrug and heroin-only . MeissneThis study is consistent with a previous investigation that found lower morphine concentrations when cocaine was co-administered . The lowIn this study, few case were positive for heroin and ethanol, where ethanol was attributed to antemortem ethanol ingestion. Moreover, the few cases may have been related to the low sample size of heroin users and the prohibition on ethanol intake by law in Saudi Arabia due to religious reasons ,60. In cNotably, In 2018, alprazolam was detected in 4 out of 15 cases; most of these cases involved polydrug intoxication, including methamphetamine, cocaine, and tramadol. In Saudi Arabia, alprazolam is a controlled drug, although the alprazolam supply has increased in illegal markets, which explains this increase. A similar trend has been observed with methamphetamine-related postmortem deaths in Jeddah, Saudi Arabia, in the same period . Abuse oConsistent with previous reports, deaths following heroin intake can be divided into three types: rapid and delayed deaths, and undetermined survival times ,3,51. RaGoldberger et al. reported similar findings to the current study and showed that a higher median free morphine concentration occurred for rapid deaths 1420 ng/mL) compared to delayed deaths (250 ng/mL), while the median morphine for undetermined survival time after ingestion (610 ng/mL) was higher than that for delayed deaths . Recentl0 ng/mL cThe concentration of morphine in the vitreous humor is often lower than that in the blood. However, this concentration was found to be dependent on the survival time following heroin administration.The use of the bile free morphine concentration to distinguish between rapid and delayed deaths has received little attention, and in most cases, the total morphine content has been reported. The total morphine concentration is significantly higher with delayed deaths, which indicates that the deceased is heroin-dependent and has received high doses of heroin . The samIn general, heroin-related deaths are most likely to occur due to accidental overdoses, although suicidal or homicidal modes of death have also been reported in the literature ,69. AbirDepression is an indicator associated with heroin abuse, and it has led to an increase in violence-related deaths among heroin users ,72. DarkOpioids, such as heroin, are sedative drugs that are rarely associated with violence ,73,74. IThe median morphine concentration reported in this study was considered higher in cases of suicide-related deaths compared to those of accidental intoxication, which is consistent with the study by Darke et al. . In mostHeroin overdose as a means of homicide has been reported, and the percentages of heroin-related homicide have varied between studies. For example, in a study by Denninng et al., almost 20% of cases were reported to be homicides by drug overdose . In otheOur findings were consistent with the study by Thiblin et al.  . A higheIn the current study, no differences were observed in the median vitreous humor concentration among the three routes of administration. The most useful information obtained by measuring vitreous humor is the source of opiates administered when 6-MAM is detected in this matrix . In contIn a study by Fugelstad et al. , patientIt has been widely reported that heroin addiction is one of the main causes of HIV, and therefore, we believe that it is important to discuss the number of individuals who died from HIV. As the discussion here pertains to an epidemiological investigation in certain parts of the world for the first time, this piece of information is important. However, one of the limitations of this study is that the infectious disease history was not detailed in all cases. HIV and hepatitis were reported in fewer than 1% and 3% of total cases, respectively, which may indicate that sharing needles is not a common practice or that HIV deaths related to heroin addiction are under-reported in Saudi Arabia, considering that deaths due to infectious diseases are not usually subjected to postmortem analysis.The location where the bodies were found following a drug overdose is an important factor when interpreting the cause and manner of death. The impacts of ecological conditions, such as temperature and humidity, and location, such as indoor and outdoor places, on the analytes of interest in the postmortem samples were investigated. Few studies have discussed the location of heroin-related deaths. Fugelstad et al.  found thIn previous studies, although putrefaction was reported, limited information regarding heroin-related metabolites was available. In the study by Crandall et al., putrefaction was observed in 12% of heroin-related deaths . Crump eThe impact of seasonal variation on heroin biomarkers and their metabolite analysis is believed to be a crucial factor underlying heroin-related deaths, especially in countries such as Saudi Arabia, where hot weather is more dominant. Kringsholm et al.  reportedIn forensic postmortem procedures, the ratio of morphine to codeine is of paramount importance in differentiating the source of opioid ingestion. A morphine-to-codeine ratio of less than one is considered an indicator of the intake of medicine containing codeine, while a morphine-to-codeine ratio of more than one is related to the use of heroin ,51,92. Tr2 = 0.01, p = 0.4), which agrees with the current investigation. In that study, the median ratio of free morphine between the bile and blood was twenty-nine, which was lower than that in the current study. Duflou et al. reported the total morphine in blood and bile, and a strong correlation for the total morphine between blood and bile was obtained when using their data, with Rs = 0.712 and a p-value of 3 × 10−5, and the median ratio of free morphine between bile and blood was 37 [Many factors that affect the connections between heroin biomarkers and their metabolites must be taken into consideration, such as the history of abuse, concomitant use of other drugs, tolerance, route of administration, and PMI ,33,44. Md was 37 . The mord was 37 . Negativd was 37 . A low md was 37 .2 = 0.697) in all cases, whereas a strong correlation was obtained in 17 cases when the deaths were described as sudden (r2 = 0.885). The same observation was reported by Rees et al. [p = 8.0 × 10−7) than delayed death cases .The correlation of morphine in the blood with the vitreous humor has been widely studied. Scott and Oliver  found ths et al. , who fouTo the best of our knowledge, this is the first epidemiological study evaluating heroin-related deaths in Jeddah, Saudi Arabia. Although the weather in Saudi Arabia is extremely hot most of the year, 6-MAM hydrolysis to morphine is favored. The detection of heroin biomarkers (6-MAM and 6-AC) is facilitated by short PMI periods in the majority of cases; moreover, the addition of sodium fluoride as a preservative prevents 6-MAM from being degraded to morphine in most cases. In addition, the availability of urine, vitreous humor, and bile samples provides valuable information on which opioids have been administered based on the detection of heroin biomarkers. The latter is important if no blood samples are available, if blood samples are negative for heroin biomarkers, and in cases of partially and heavily decomposed bodies. The incidence of heroin deaths in Jeddah remained stable during the study period. Most individual deaths likely occurred within groups, but the body was left behind or moved owing to fear among users to call an ambulance. Although only 24% of the deceased had medical records, the findings indicated an improvement in health reporting regarding drug abuse in Saudi Arabia. It is highly recommended that heroin users be encouraged to contact ambulances and trained in resuscitation. This study concluded that most patients were unemployed (up to 53%), had started taking heroin in their teens, and had been admitted several times to the addiction center. Therefore, the loss of tolerance following detoxification might have been the primary cause of many heroin-related deaths.


During a fire, ordinary Portland cement (OPC) systems lose their mechanical properties. For this reason, it is important to find a way to protect it. This study suggested alternative uses of slag and phosphogypsum to produce coatings for fire-resistant applications. Five compositions of 10 mm thick alkali-activated slag coatings were investigated. In these compositions, different amounts of phosphogypsum  were used. In the first stage of this study, the residual compressive strength of samples with the coatings based on alkali-activated slag was compared to the results of OPC concrete samples without coatings. The experimental results showed that a higher residual compressive strength of 33.2–47.3 MPa OPC concrete was achieved for the samples with coatings. Meanwhile, the residual compressive strength of the uncoated samples was 32.37 MPa. In the second stage, OPC concrete samples were reinforced with fiberglass polymer (FRP) rods, and they had a similar positive effect on alkali-activated coatings. After exposure to higher temperatures, the pullout tests of the glass FRP bars showed that the adhesion strength was (9.44 MPa) 43.9% higher for the samples with coatings compared to the samples without coatings (6.56 MPa). Therefore, a higher bond strength can be maintained between concrete and FRP bars. Alkali-activated slag with 3% phosphogypsum can be used for the production of fire-resistant coating. These coatings could protect OPC concrete and reinforced concrete with glass FRP bars from fire. The firing tests showed that the plates made from this porous material had better fire resistance than usual rock wool. The back side of the panel had no more than 100 °C temperature; meanwhile, the front panel side had 800 °C temperature (under flames) after 1 h. Ordinary Portland cement (OPC) concrete is a non-combustible material  and has a slow rate of heat transfer, but this material, like other non-combustible material, can be destroyed by fire. The main purpose of concrete significant strength loss could be calcium oxide, which was formed at elevated temperatures. Khoury et al.  stated t2:Na2O = 3.1) and metakaolin. These coatings were applied as a thermal barrier for concrete structures. After calcination at 1000 °C for 1 h, the coatings had an X-ray amorphous structure. Thermogravimetric analysis of two geopolymer compositions showed suitable thermal stability of this material at temperatures of up to 1000 °C. These materials had. Sakkas et al. [2, with a highly alkaline aqueous phase of potassium hydroxide to form a paste, which was then cured for some time at 70 °C. The incorporation of solid SiO2. The addition of solid SiO2 was important to make the geopolymer fire resistant at temperatures up to 1350 °C. After the test, the surface of the geopolymer was scrubbed and cracked without losing structural integrity. Thus, the concrete slab protected by the geopolymer did not experience any form of compression or a decrease in its compression strength. In the later research [Previous studies on the use of alkali-activated materials for coatings that protect OPC concrete from fire have shown great potential for this type of coating. Protective coatings are used to insulate and protect the surfaces of Portland cement concrete. Krivenko et al.  experimes et al. ,16,17,18s et al. . In anotresearch  determinresearch , the datThe main properties of alkali-activated materials or geopolymers from which fire protection coatings are made are closely related to geopolymerization and hydration mechanisms. After the aluminosilicate precursor was filled with alkali solution, the activation process started. During the geopolymerization reactions, precursors of the active form were dissolved in the alkaline solution, and new aluminosilicate phases were formed. Zeolitic crystalline compounds, C–S–H and C–A–S–H, and amorphous alumino-silicate structures are detected in the slag hydration products ,22. ThesIn this study, the original composition of alkali-activated slag was suggested. The aim of this research was to investigate the potential use of alkali-activated slag as a coating to protect concrete samples without reinforcement and with glass fiber polymer reinforcement in high-temperature applications. An alkali–alkali-activated slag system with phosphogypsum was chosen because both initial materials are by-products. Large amounts of the phosphogypsum are accumulated, and only a small amount of them is reused. The aim is to reduce the amount of waste in the context of the circular economy.2/kg. The 0/4 fraction sand from the Kvesai quarry was used as fine aggregate, and 5/16 fraction granite macadam was used as coarse aggregate. Concrete samples—cubes (100 × 100 × 100) mm were formed using the compositions from In this study, Portland cement CEM I 42.5 R was used as a binding material for the production of concrete samples. This cement was produced by the company “Akmenes cementas” . The initial setting time of Portland cement was 140 min, and the final setting time was 190 min   concrete samples were covered with 50 mm thick alkali-activated materials. Three samples were formed for each mixture. The properties of the (OPC) concrete samples with alkali-activated slag coatings were compared with the properties of reference samples without alkali-activated slag coatings. All samples were cured under the same conditions.2/kg), the oxides of CaO and SiO2 predominated: CaO is 45.20%, SiO2 is 37.10%, Al2O3 is 6.44%, MgO is 5.76%, SO3 is 1.85%, and other chemical element oxides in amounts not exceeding 1% . Semi-hydrate phosphogypsum generated by fertilizer plants was used as well. The main mineral of phosphogypsum was CaSO4 0.5H2O (up to 98%), and in this case, chemical analysis methods were used. However, there are impurities of phosphorus and fluoride compounds. The five types of alkali-activated slag coatings were prepared in this research  and covered with polyethylene material, which protects the water evaporation. Other samples were covered with alkali-activated slag coatings, as shown in On the first curing day (24 h), samples coated or uncoated with alkali-activated slag coatings were cured at ambient temperature (22 °C). On the second day, after 24 h, samples were cured at the temperature of 60 °C in the oven, and finally, they were cured again at ambient temperature for the last 26 days. After 28 days of hydration, samples were exposed to the temperatures caused by fire for up to three hours to evaluate the potential of alkali-activated coatings for fire protection of Portland cement concrete.Some of the OPC concrete samples were reinforced with fiberglass polymer (FRP) rods. The diameter of the reinforcement used for the tests was 10 mm.X-ray fluorescence analysis (XRFA) and chemical composition analysis were used for the determination of the oxygen composition of initial materials such as OPC, slag, and phosphogypsum. The XRFA analysis of slag was performed using a fluorescence spectrometer S8 Tiger  operating at the counter gas helium 2 bar. This spectrometer is equipped with a Rh tube with an energy of up to 60 keV. Powder samples  were measured in He atmosphere, and the data were analyzed with SPECTRAPlus QUANT EXPRESS standardless software .The chemical composition of phosphogypsum was determined by the classical methods of chemical analysis according to the standards  rods a with vil = 5 d). Without a mechanical anchor, the heads of the reinforcement bars were investigated [la—the anchoring length of the reinforcing bar, mm; The anchoring length of the reinforcement bars was the same for all samples, and the reinforcement bars were incorporated in the middle of the concrete cube. The ends of the reinforcement were embedded in plastic tubes to form an anchoring portion of a rod of a certain length  as follows:The analysis and test measurements used in the study contribute to the potential use of alkaline-activated slag as a coating to protect unreinforced and reinforced glass fiber polymer concrete samples at high temperatures .Concrete temperature testing at fire-induced temperatures can be used to monitor concrete temperature variations, which are closely related to concrete strength development. Concrete samples (cubes) without and with alkali-activated slag coatings were exposed to the fire-induced temperature test wall for up to three hours . The devIt was seen that the first thermocouples were mounted closest to the temperature-exposed surface (15 mm), so the highest temperatures (453–783 °C) were recorded compared to the temperatures reached by the second and third thermocouples b. DuringDifferences in measured temperatures were lower for other thermocouples, which had a greater distance from the affected surface c,d. The For the comparison of temperatures in different thermocouples after one hour, the values of the measured temperatures are provided in The residual strength of concrete is needed to assess the safety of concrete structures after a fire. The potency of concrete samples to withstand elevated temperatures was based on the values of residual compressive strength that were observed before and after the fire resistance test. The evaluation of concrete samples’ compressive strength after the fire resistance test was carried out in order to determine the effect of high temperature on the compressive strength of concrete. Before the fire resistance test , the compressive strength of the reference samples was 56.5 MPa. After fire testing, the residual compressive strength of concrete samples was measured . In all At elevated temperatures, the mineral composition of alkali-activated slag coatings changed. In our previous study , mineralAfter three hours of the fire resistance test, the residual compressive strength of the reference sample decreased to 32.37 MPa, which consisted of 57.26% compared to the compressive strength before the fire resistance test. The residual compressive strength of concrete samples was reached by 58.8–83.7% (33.24–47.31 MPa) for samples with alkali-activated slag coatings after the fire resistance test. The residual compressive strength of the concrete samples with 3S protective coating was only 83.69% after the fire resistance test. Similar values of the residual strength (87%) of alkali-activated aluminosilicate binder-based adhesives were determined by Krivenko et al. .+ ions and alkali–alkali earth hydro aluminosilicates  formed during the hydration process. These minerals predetermine the smooth course of their dehydration and topotactic recrystallization into anhydrous compounds, such as calcium, magnesium, and plagioclase silicates, without disturbing the structure of the hardened cement stone. In the OPC system, these compounds were not detected. Rovnaník et al. [Therefore, these concrete samples with alkali-activated slag coatings exhibited better thermal stability than only concrete samples without these coatings. The high-temperature behavior of alkali-activated slag differs from conventional Portland cement systems. The differences are closely related to the mineral composition of these systems. In the composition of an alkali-activated slag system, calcium hydrosilicates modified with Nak et al.  determinThe compressive strength of the coatings before and after the fire resistance test was determined in our previous study . This stIn the production of reinforced concrete, the use of reinforcement made from glass fiber polymer (FRP) bars instead of steel has become more popular . High teIn elevated temperatures, the adhesion of glass FRP bars and concrete could change. Initially, the pullout tests of the fiberglass GFRP bars reinforced concrete was determined. This bond strength of the reference sample before exposure to elevated temperatures consisted of 13.3 MPa .The bond strength behavior of glass FRP bars and concrete decreased at elevated temperatures. After exposure to elevated temperatures, the bond strength of concrete samples without protective coatings (TC) was 56% lower (6.6 MPa) compared to the reference samples before exposure to elevated temperatures (13.3 MPa). The alkali-activated slag coatings had a positive effect on the bond strength of glass FRP bars and concrete. The highest values of bond strength were maintained by the samples with a protective T3%  was higher by 43.9% than the bond strength of the reference sample (6.56 MPa).It could be stated that alkali-activated slag coatings with the addition of phosphogypsum for 3% could be used as a fire-resistant coating. It increased the fire resistance of Portland cement concrete and improved the bond strength of concrete and glass fiber polymer bars at elevated temperatures.