The effect of clay therapy on hopelessness and depression levels in chronic stroke patients in addition to physical therapy.

BACKGROUND: Clay art therapy can be used as part of rehabilitation for chronic stroke patients. OBJECTIVE: The objective of this study is to examine the effect of clay therapy on hopelessness and depression levels in chronic stroke patients who receive physical therapy and compare them to patients who only receive physical therapy. METHODS: This randomized controlled study was conducted between August 1st - September 28th, 2022 in Turkiye, with 60 patients who agreed to participate in the study and met the inclusion criteria, which were chronic stroke patients who received physical therapy. The patients were divided into two groups (30 in the experimental group, 30 in the control group) with the control group receiving only their routine physical therapy and rehabilitation (5 days a week, 40 sessions in total), while the experimental group received their routine physical therapy and rehabilitation program as well as clay therapy twice a week, 60 min per session, for 8 weeks. Demographic information of all the participants was recorded, and the Beck Depression Inventory and Beck Hopelessness Scale were administered before and after treatment. RESULTS: The patients' depression posttest scores (t(58) = -11.386; p = 0.000 < 0,05), and hopelessness posttest scores (t(58) = -10.247; p = 0.000 < 0,05) differed significantly based on their groups. The control group's depression posttest scores (x¯ =25,033) and hopelessness posttest scores (x¯ =15,000) were higher than the experimental group's depression posttest scores (x¯ =9,067) and hopelessness posttest scores (x¯ =8,000). The control group's feeling about the future posttest scores (x¯ =2,967) were higher than the experimental group's posttest scores (x¯ =0,967). The control group's loss of motivation posttest scores (x¯ =6,400) were higher than the experimental group's posttest scores (x¯ =2,667). CONCLUSION: It was seen that clay therapy, in addition to physical therapy, was effective in reducing depression and hopelessness in chronic stroke patients.

Effects of a Curcumin/Silymarin/Yeast-Based Mycotoxin Detoxifier on Redox Status and Growth Performance of Weaned Piglets under Field Conditions.

The aim of this in vivo study was to investigate the effects of a novel mycotoxin detoxifier whose formulation includes clay (bentonite and sepiolite), phytogenic feed additives (curcumin and silymarin) and postbiotics (yeast products) on the health, performance and redox status of weaned piglets under the dietary challenge of fumonisins (FUMs). The study was conducted in duplicate in the course of two independent trials on two different farms. One hundred and fifty (150) weaned piglets per trial farm were allocated into two separate groups: (a) T1 (control group): 75 weaned piglets received FUM-contaminated feed and (b) T2 (experimental group): 75 weaned piglets received FUM-contaminated feed with the mycotoxin-detoxifying agent from the day of weaning (28 days) until 70 days of age. Thiobarbituric acid reactive substances (TBARSs), protein carbonyls (CARBs) and the overall antioxidant capacity (TAC) were assessed in plasma as indicators of redox status at 45 and 70 days of age. Furthermore, mortality and performance parameters were recorded at 28, 45 and 70 days of age, while histopathological examination was performed at the end of the trial period (day 70). The results of the present study reveal the beneficial effects of supplementing a novel mycotoxin detoxifier in the diets of weaners, including improved redox status, potential hepatoprotective properties and enhanced growth performance.

Rare Earth Element Adsorption to Clay Minerals: Mechanistic Insights and Implications for Recovery from Secondary Sources.

The energy transition will have significant mineral demands and there is growing interest in recovering critical metals, including rare earth elements (REE), from secondary sources in aqueous and sedimentary environments. However, the role of clays in REE transport and deposition in these settings remains understudied. This work investigated REE adsorption to the clay minerals illite and kaolinite through pH adsorption experiments and extended X-ray absorption fine structure (EXAFS). Clay type, pH, and ionic strength (IS) affected adsorption, with decreased adsorption under acidic pH and elevated IS. Illite had a higher adsorption capacity than kaolinite; however, >95% adsorption was achieved at pH ∼7.5 regardless of IS or clay. These results were used to develop a surface complexation model with the derived binding constants used to predict REE speciation in the presence of competing sorbents. This demonstrated that clays become increasingly important as pH increases, and EXAFS modeling showed that REE can exist as both inner- and outer-sphere complexes. Together, this indicated that clays can be an important control on the transport and enrichment of REE in sedimentary systems. These findings can be applied to identify settings to target for resource extraction or to predict REE transport and fate as a contaminant.

Solidification/stabilization and optimization of municipal solid waste incineration fly ash with aluminosilicate solid wastes.

Alkali-activation is an effective municipal solid waste incineration fly ash (MSWIFA) solidification/stabilization (S/S) technology. However, the characteristics of calcium-rich silica-poor aluminum phase in MSWIFA easily cause the structural instability and contamination of alkali activated MSWIFA S/S bodies. Therefore, the aluminosilicate solid wastes are used in this work to optimize the immobilization and structural properties. Results showed that incorporation of aluminosilicate solid wastes significantly improved the compressive strength and heavy metals pollution toxicity of MSWIFA S/S bodies. Compared to alkali activated MSWIFA, the compressive strength of S/S bodies with addition of coal fly ash, silica fume and granulated blast furnace slag improved by 31.0%, 47.6% and 50.8% when the curing time was 28 days, respectively. Leachability of Pb, Zn and Cd in these alkali activated MSWIFA S/S bodies was far below the threshold value specified in Standard GB16889. Aluminosilicate solid wastes provided abundant Si/Al structural units, and some new phases such as ettringite(AFt, 3CaO⋅Al2O3⋅3CaSO4⋅32H2O), calcium sulfoaluminate hydrate (3CaO⋅Al2O3⋅CaSO4⋅12H2O) and Friedel's salt (CaO⋅Al2O3⋅CaCl2⋅10H2O) can be detected in S/S matrix with aluminosilicate solid wastes, along comes increased the amount of the amorphous phases. Lower Ca/Si molar ratio tended to form the network structure gel similar to tobermorite with higher polymerization degree. Meanwhile, the silica tetrahedron of the gels changed from the oligomerization state like island to the hyperomerization state like chain, layer network or three-dimensional structure, and average molecular chain length increased. These findings provide theoretical basis for structural properties optimization and resource utilization of MSWIFA S/S matrices.

Rice husk ash based growing media impact on cucumber and melon growth and quality.

Rice husk, an agricultural waste from the rice industry, can cause serious environmental pollution if not properly managed. However, rice husk ash (RHA) has been found to have many positive properties, making it a potential replacement for non-renewable peat in soilless planting. Thus, this study investigated the impact of a RHA composite substrate on the growth, photosynthetic parameters, and fruit quality of cucumber (Yuyi longxiang variety) and melon (Yutian yangjiaomi variety). The RHA, peat, vermiculite, and perlite were blended in varying proportions, with the conventional seedling substrate (peat:vermiculite:perlite = 1:1:1 volume ratio) serving as the control (CK). All plants were cultivated in barrels filled with 10L of the mixed substrates. The results from this study found that RHA 40 (RHA:peat:vermiculite:perlite = 4:4:1:1 volume ratio) significantly enhanced substrate ventilation and positively influenced the stem diameter, root activity, seedling index, chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of cucumber and melon plants. Additionally, plant planted using RHA 40, the individual fruit weight of cucumber and melon found to increase by 34.62% and 21.67%, respectively, as compared to the control. Aside from that, both cucumber and melon fruits had significantly higher sucrose, total soluble sugar, vitamin C, and soluble protein levels. This subsequently improved the activity of sucrose synthase and sucrose phosphate synthase in both cucumber and melon. In conclusion, the RHA 40 found to best promote cucumber and melon plant growth, increase plant leaf photosynthesis, and improve cucumber and melon fruit quality, making it a suitable substrate formula for cucumber and melon cultivation in place of peat.

The influence of using different types of modified vermiculite cover on ammonia mitigation from animal slurry storage: The role of sulfuric acid.

Animal slurry storage is an important ammonia (NH3) emission source. Sulfuric acid (H2SO4)-modified vermiculite coverage is a new promising technology for controlling NH3 emission from slurry storage. However, the underlying mechanisms in controlling the mitigation effect remain unclear. Here, a series of experiments to determine the effect of H2SO4 on the modified vermiculite properties, floating persistence, and NH3 mitigation effect was conducted. Results showed that abundant H2SO4 and sulfate remained on the outer surface and in the extended inner pores of the vermiculite with acidifying H+ concentrations higher than 5 M. An initial strong instantaneous acidification of surface slurry released rich carbon dioxide bubbles, strengthening cover floating performance. An acidification in the vermiculite cover layer and a good coverage inhibition interacted, being the two leading mechanisms for mitigating NH3 during initial 40-50 days of storage. The bacterial-amoA gene dominated the conversion of NH3 to nitrous oxide after 50 days of storage. Vermiculite with 5 M H+ modification reduced the NH3 emissions by 90 % within the first month of slurry storage and achieved a 64 % mitigation efficiency throughout the 84 days period. With the development of the aerial spraying equipment such as agricultural drones, acidifying vermiculite coverage hold promise as an effective method for reducing NH3 emission while absorbing nutrients from liquid slurry storage tank or lagoon. This design should now be tested under field conditions.

A comparative study on the Cs adsorption/desorption and structural changes in different clay minerals.

We investigated the structural changes in clay minerals after Cs adsorption and understood their low desorption efficiency using an ion-exchanger. We focused on the role of interlayers in Cs adsorption and desorption in 2:1 clay minerals, namely illite, hydrobiotite, and montmorillonite, using batch experiments and XRD and EXAFS analyses. The adsorption characteristics of the clay minerals were analyzed using cation exchange capacity (CEC), maximum adsorption isotherms (Qmax), and radiocesium interception potential (RIP) experiments. Although illite showed a low CEC value, it exhibited high selectivity for Cs with a relatively high RIP/CEC ratio. The Cs desorption efficiency after treatment with a NaCl ion exchanger was the highest for illite (74.3%), followed by hydrobiotite (45.5%) and montmorillonite (30.3%); thus, Cs adsorbed onto planar sites, rather than on interlayers or frayed edge sites (FESs), is easily desorbed. After NaCl treatment, XRD analysis showed that the low desorption efficiency was due to the collapse of the interlayer-fixed Cs, which tightly narrowed the interlayers' hydrobiotite due to the ion exchange of divalent cations (Mg2+ or Ca2+) into the monovalent cation (Na+). Moreover, EXAFS analysis showed that hydrobiotite formed inner-sphere structures after NaCl desorption, indicating that it was difficult to remove Cs from NaCl desorption due to the collapsed hydrobiotite and montmorillonite interlayers as well as the strong bonding in FESs of illite. In contrast, chelation desorption using oxalic acid effectively dissolved the narrowed interlayers of hydrobiotite (98%) and montmorillonite (85.26%), enhancing the desorption efficiency. Therefore, low desorption efficiency for Cs clays using an ion exchanger was caused by the collapsed interlayer due to the exchange between monovalent cation and divalent cation.

Characterization of potassium-solubilizing fungi, Mortierella spp., isolated from a poplar plantation rhizosphere soil.

Potassium-solubilizing microorganisms are capable of secreting acidic chemicals that dissolve and release potassium from soil minerals, thus facilitating potassium uptake by plants. In this study, three potassium-dissolving filamentous fungi were isolated from the rhizosphere soil of a poplar plantation in Jiangsu Province, China. Phylogenetic analyses based on ITS, 18 S, and 28 S showed that these three isolates were most similar to Mortierella. These strains also possessed spherical or ellipsoidal spores, produced sporangia at the hyphal tip, and formed petal-like colonies on PDA media resembling those of Mortierella species. These findings, along with further phenotypic observations, suggest that these isolates were Mortierella species. In addition, the potassium-dissolution experiment showed that strain 2K4 had a relatively high potassium-solubilizing capacity among these isolated fungi. By investigating the influences of different nutrient conditions (carbon source, nitrogen source, and inorganic salt) and initial pH values on the potassium-dissolving ability, the optimal potassium-solubilization conditions of the isolate were determined. When potassium feldspar powder was used as an insoluble potassium source, isolate 2K4 exhibited a significantly better polysaccharide aggregation ability on the formed mycelium-potassium feldspar complex. The composition and content of organic acids secreted by strain 2K4 were further detected, and the potassium-dissolution mechanism of the Mortierella species and its growth promotion effect were discussed, using maize as an example.

Stabilization of heavy metals in solid waste and sludge pyrolysis by intercalation-exfoliation modified vermiculite.

Increasing amounts of solid waste and sludge have created many environmental management problems. Pyrolysis can effectively reduce the volume of solid waste and sludge, but there is still the problem of heavy metal contamination, which limits the application of pyrolysis in environmental management. The intercalated-exfoliated modified vermiculite (IEMV) by intercalators of sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide were used to control the release of Cd, Cr, Cu, Zn and Pb during pyrolysis process of sludge or solid waste. The retention of heavy metals in sludge was generally better than that in solid waste. The IEMV by octadecyltrimethylammonium bromide as the intercalator calcined 800 °C (STAB-800) was the best additive for heavy metal retention, and the retention of Cr, Cu and Zn was significantly better than that of Pb and Cd. Cr, Cu, Zn and Pb were at low risk, while Cd had considerable risk under certain circumstances. New models were proposed to comprehensively evaluate the results of the risk and forms of heavy metals, and the increasing temperature was beneficial in reducing the hazards of heavy metals by the addition of STAB-800. The reaction mechanism of heavy metals with vermiculite was revealed by simulation of reaction sites, Fukui Function and Frontier Molecular Orbital. Thermal activation-intercalated-exfoliated modified vermiculite (T-IEMV) is more reactive and had more active sites for heavy metals. Mg atoms and outermost O atoms are the main atoms for T-IEMV to react with heavy metals. The Cr, Cu and Zn have better adsorption capacity by T-IEMV than Pb and Cd. This study provides a new insight into managing solid waste and sludge and controlling heavy metal environmental pollution.

Evaluation of organo-vermiculites as sorbent phases for solid-phase extraction of ibuprofen from water.

The study of ibuprofen (IBU) preconcentration was carried out making use of a homemade column for solid-phase extraction (SPE), using vermiculite (VT) or organo-vermiculites (OVTs) as sorbent phases. Aqueous samples (50.0 mL) percolated the column and IBU was sorbed onto the VT or OVT and then desorbed using acetonitrile. Employing this SPE system and OVT, calibration curves were generated for IBU, by spectrophotometric quantification using the α-naphthylamine method. R2 values higher than 0.9950 and LOD between 12 and 18 µg L-1 were observed, for real enrichment factors of 21 and 31, by using OVTs. The analytical protocol was applied to three water samples, which were spiked with IBU solutions to evaluate the precision and accuracy of the method. Recoveries between 77 and 110% at three different IBU concentrations and RSD lower than 18% were observed, even by using the spectrophotometric method. The protocol developed in this study demonstrated that the OVT was appropriate to work as a preconcentration phase for IBU determination in water samples.

Flexible nanohybrid substrates utilizing gold nanocubes/nano mica platelets with 3D lightning-rod effect for highly efficient bacterial biosensors based on surface-enhanced Raman scattering.

In this study, gold nanocubes (AuNCs) were quickly synthesized using the seed-mediated growth method and reduced onto the surface of two-dimensional (2D) delaminated nano mica platelets (NMPs), enabling the development of AuNCs/NMPs nanohybrids with a 3D lightning-rod effect. First, the growth-solution amount can be changed to easily adjust the AuNCs average-particle size within a range of 30-70 nm. The use of the cationic surfactant cetyltrimethylammonium chloride as a protective agent allowed the surface of AuNCs and nanohybrids to be positively charged. Positively charged nanohybrid surfaces presented a good adsorption effect for detecting molecules with negative charges on the surface. Additionally, the NMP surfaces were rich in ionic charges and provided a large specific surface area for stabilizing the growth of AuNCs. Delaminated AuNCs/NMPs nanohybrids can generate a 3D hotspot effect through self-assembly to enhance the Raman signal. Surface-enhanced Raman scattering (SERS) is highly sensitive in detecting adenine biomolecules. Its limit of detection (LOD) and Raman enhancement factor reached 10-9 M and 3.6 × 108, respectively. Excellent reproducibility was obtained owing to the relatively regular arrangement of AuNC particles, and the relative standard deviation (RSD) was 10.7%. Finally, the surface of NMPs was modified by adding the hydrophilic poly(oxyethylene)-diamine (POE2000) and amphiphilic PIB-POE-PIB copolymer at different weight ratios. The adjustment of the surface hydrophilicity and hydrophobicity of AuNCs/NMPs nanohybrids led to better adsorption and selectivity for bacteria. AuNCs/POE/NMPs and AuNCs/PIB-POE-PIB/NMPs were further applied to the SERS detection of hydrophilic Staphylococcus aureus and hydrophobic Escherichia coli, respectively. The SERS-detection results suggest that the LOD of hydrophilic Staphylococcus aureus and hydrophobic Escherichia coli reached 92 CFU mL-1 and 1.6 × 102 CFU mL-1, respectively. The AuNCs/POE/NMPs and AuNCs/PIB-POE-PIB/NMPs nanohybrids had different hydrophilic-hydrophobic affinities, which greatly improved the selectivity and sensitivity for detecting bacteria with different hydrophilicity and hydrophobicity. Therefore, fast, highly selective, and highly sensitive SERS biological-detection results were obtained.

Evaluation of microstructure evolution and mechanical properties of Al-10Zn-1.63Si/Irvingia gabonensis particulates alloy composites.

This study demonstrates the feasibility of using Irvingia gabonensis shell particulates (IGSp) as alternative reinforcing materials in the development of aluminium-based composites. In this experimental study, the microstructure, phase composition, and mechanical behaviour of Al-10Zn-1.63Si/xIGSp (wt%, x = 1, 3, 5 and 7) composites were investigated. The Al-10Zn-1.63Si based composites were fabricated using the stir-casting technique. Different weight percentages (1, 3, 5 and 7) of IGSp were added to the Al-10Zn-1.63Si matrix. The chemical constituents of the IGSp were determined using X-ray fluorescence (XRF). The grain characteristics and phase(s) compositions were determined using Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD). The ultimate tensile strength, hardness, and impact strength of the developed composites were also determined. The SEM and XRD results revealed the presence of different phases: aluminium phosphate (Al16P16O64), gahnite (ZnAl2O4), andalusite (Al2SiO5), Quartz (SiO2) and aluminium silicate (Al2O3.5.SiO2). Results show that addition of IGSp led to an increase in ultimate tensile strength, with the highest value (128 MPa) obtained at 3 wt% IGSp. The hardness of the composites increased with increasing concentrations of IGSp, reaching a maximum value of 285 HV after adding 7 wt% IGSp. The impact strength improved with the addition of IGSp, with the highest value (30 J) obtained at 1 wt% IGSp. The improvements in mechanical properties were attributed to the dispersion of three major phases: aluminium silicate (Al2O3.54.SiO2), Al16P16O64 and Al2O3.54.SiO2. These phases contributed to the enhanced strength and hardness of the composites. The study noted a sudden decrease in ultimate tensile strength with higher concentrations of IGSp due to the increase in the intensities of Al16P16O64 and precipitation of hard but brittle new phase; Al2Si60.6O126.33. The study concludes that IGSp has the potential to serve as an alternative reinforcing material for aluminium-based composites.

Effective stabilization of heavy metals in solid waste and sludge pyrolysis using intercalated-exfoliated modified vermiculite: Experiment and simulation study.

Pyrolysis is effective in reducing the volume of solid waste and sludge, and produces less pollutants than incineration and landfill, but the process still suffers from heavy metal pollution. Four types of intercalated-exfoliated modified vermiculite (UIV, DIV, TIV and 3IV) were prepared using urea, dimethylsulfoxide, tributyl phosphate and 3-aminopropyltriethoxysilane as intercalators for the control of Cd, Cr, Cu, Pb and Zn in municipal sewage sludge (MSL), paper mill sludge (PML), municipal domestic waste (MWA) and aged refuse (AFE). The larger the interlayer spacing of the vermiculite, the more favorable the retention of heavy metals. 3IV was the most effective additive, with an average retention of more than 75 % of all heavy metals at 450 ℃ for the four raw materials. Cr, Cu, Pb and Zn were all at low potential ecological risk (Pr), while Cd was moderate or considerable Pr, and the addition of 3IV reduced the Pr. Distribution of intercalators between vermiculite interlayers was haphazard, and interlayer spacing results were close to those of the experiment (except for tributyl phosphate). The reactive electrons mainly flowed from the Highest Occupied Molecular Orbital (HOMO) of vermiculite flakes to the Lower Unoccupied Molecular Orbital (LUMO) of heavy metal chlorides. In contrast, the reactive electrons mostly flowed from the HOMO of heavy metal oxides to the LUMO of vermiculite flakes. Heavy metal oxides were more readily adsorbed on vermiculite flakes than heavy metal chlorides, and the adsorption capacity of Cr and Zn was stronger than that of Cd, Pb and Cu.

Optimized 3D printed zirconia-reinforced leucite with antibacterial coating for dental applications.

OBJECTIVES: This study aims to produce by robocasting leucite/zirconia pieces with suitable mechanical and tribological performance, convenient aesthetics, and antibacterial properties to be used in dental crown replacement. METHODS: Leucite pastes reinforced with 12.5%, 25%, and 37.5% wt. ZrO2 nanoparticles were prepared and used to print samples that after sintering were characterized in terms of density, shrinkage, morphology, porosity, mechanical and tribological properties and translucency. A coating of silver diamine fluoride (SDF) and potassium iodide (KI) was applied over the most promising material. The material's antibacterial activity and cytotoxicity were assessed. RESULTS: It was found that the increase of ZrO2 reinforcement up to 25% enhanced both microhardness and fracture toughness of the sintered composite. However, for a superior content of ZrO2, the increase of the porosity negatively affected the mechanical behaviour of the composite. Moreover, the composite with 25% ZrO2 exhibited neglectable wear in chewing simulator tests and induced the lowest wear on the antagonist dental cusps. Although this composite exhibited lower translucency than human teeth, it was three times higher than the ZrO2 glazed material. Coating this composite material with SDF+KI conferred antibacterial properties without inducing cytotoxicity. SIGNIFICANCE: Robocasting of leucite reinforced with 25% ZrO2 led to best results. The obtained material revealed superior optical properties and tribomechanical behaviour compared to glazed ZrO2 (that is a common option in dental practice). Moreover, the application of SDF+KI coating impaired S. aureus proliferation, which anticipates its potential benefit for preventing pathogenic bacterial complications associated with prosthetic crown placement.

Eco-friendly natural mineral biotite as a cesium adsorbent: Utilizing low-concentration acid and hydrogen peroxide.

Biotite, a phyllosilicate mineral, possesses significant potential for cesium (Cs) adsorption owing to its negative surface charge, specific surface area (SSA), and frayed edge sites (FES). Notably, FES are known to play an important role in the adsorption of Cs. The objectives of this study were to investigate the Cs adsorption capacity and behavior of artificially weathered biotite and identify mineralogical characteristics for the development of an eco-friendly geologically-based Cs adsorbent. Through various analyses, it was confirmed that the FES of biotite was mainly formed by mineral structural distortion during artificial weathering. The Cs adsorption capacity is improved by approximately 39% (from 20.53 to 28.63 mg g-1) when FES are formed in biotite through artificial weathering using a low-concentration acidic solution mixed with hydrogen peroxide (H2O2). Especially, the Cs selectivity in Cs-containing seawater, including high concentrations of cations and organic matter, was significantly enhanced from 203.2 to 1707.6 mL g-1, an increase in removal efficiency from 49.5 to 89.2%. These results indicate that FES of artificially weathered biotite play an essential role in Cs adsorption. Therefore, this simple and economical weathering method, which uses a low-concentration acidic solution mixed with H2O2, can be applied to natural minerals for use as Cs adsorbents.

Influence of Peptoid Sequence on the Mechanisms and Kinetics of 2D Assembly.

Two-dimensional (2D) materials have attracted intense interest due to their potential for applications in fields ranging from chemical sensing to catalysis, energy storage, and biomedicine. Recently, peptoids, a class of biomimetic sequence-defined polymers, have been found to self-assemble into 2D crystalline sheets that exhibit unusual properties, such as high chemical stability and the ability to self-repair. The structure of a peptoid is close to that of a peptide except that the side chains are appended to the amide nitrogen rather than the α carbon. In this study, we investigated the effect of peptoid sequence on the mechanism and kinetics of 2D assembly on mica surfaces using in situ AFM and time-resolved X-ray scattering. We explored three distinct peptoid sequences that are amphiphilic in nature with hydrophobic and hydrophilic blocks and are known to self-assemble into 2D sheets. The results show that their assembly on mica starts with deposition of aggregates that spread to establish 2D islands, which then grow by attachment of peptoids, either monomers or unresolvable small oligomers, following well-known laws of crystal step advancement. Extraction of the solubility and kinetic coefficient from the dependence of the growth rate on peptoid concentration reveals striking differences between the sequences. The sequence with the slowest growth rate in bulk and with the highest solubility shows almost no detachment; i.e., once a growth unit attaches to the island edge, there is almost no probability of detaching. Furthermore, a peptoid sequence with a hydrophobic tail conjugated to the final carboxyl residue in the hydrophilic block has enhanced hydrophobic interactions and exhibits rapid assembly both in the bulk and on mica. These assembly outcomes suggest that, while the π-π interactions between adjacent hydrophobic blocks play a major role in peptoid assembly, sequence details, particularly the location of charged groups, as well as interaction with the underlying substrate can significantly alter the thermodynamic stability and assembly kinetics.

Conventional-, bulk-fill- or flowable-resin composites as prosthetic core build-up: Influence on the load-bearing capacity under fatigue of bonded leucite-reinforced glass-ceramic.

This study aimed to evaluate the fatigue performance of simplified ceramic restorations (leucite-reinforced glass ceramic) adhesively cemented onto substrates of different resin composites. Three options from the same commercial line were selected (Tetric N-Line, Ivoclar), classified as Conventional (CRC), Bulk-fill (BRC) and Flowable (FRC), which were used to make discs using a cylindrical metallic device (n = 19; Ø = 10 mm, thickness = 2.0 mm). A total of 57 discs (Ø = 10 mm, thickness = 1.0 mm) were made from CAD/CAM prefabricated blocks of a leucite reinforced glass-ceramic (Empress CAD, Ivoclar) to simulate a monolithic restoration, then were randomly distributed to be bonded on 19 discs of each three different resin composite substrates (CRC; BRC; or FRC) with a dual resin cement (Multilink N; Ivoclar). The samples were subjected to a compression test with a hemispherical stainless-steel piston (Ø = 40 mm) at a monotonic regimen (n = 4; 1 mm/min loading rate and 500 kgf loading cell until fracture). The cyclic fatigue test was performed underwater at a frequency of 20 Hz (n = 15). The first step was applied using 200N for 5000 cycles, followed by increments of 50N at each step of 10,000 until failure. The outcome considered for both tests was the occurrence of radial crack. Specific statistical tests (α = 0.05) were performed for monotonic (One-way ANOVA; Tukey's test) and fatigue data (Kaplan-Meier test; Log-rank test). Fractography of fractured samples were also performed. The FRC group had the lowest failure load in both test regimes (p < 0.05; monotonic: 726.64N; fatigue: 716.67N). There were no differences between the CRC and BRC groups (p > 0.05; monotonic: 989.30 and 990.11N; fatigue: 810.00 and 833.33N, respectively). The same result was obtained considering cycles for fatigue failure (FRC < CRC=BRC). Leucite glass-ceramic bonded to substrates made of flowable resin composite behaves worse mechanically than bonding to conventional or bulk-fill resin composite substrates.

CAD/CAM leucite-reinforced glass-ceramic for simulation of attrition in human enamel in vitro.

OBJECTIVE: Investigate attrition simulation using CAD/CAM leucite-reinforced glass-ceramic antagonists on occlusal vs. buccal enamel. METHODS: Three dental materials with known wear rates (resin-modified glass-ionomer, micro-filled, and fine particle composites) validated the wear simulator (CAD/CAM glass-ceramic antagonists, 200 cycles, 80 N load, deionised water irrigation, 0.7 mm sliding movement). Following this, human molars were sectioned into paired occlusal and buccal polished samples (n = 8/gp). Exposed 1.5 mm Ø enamel areas were subjected to attritional wear with and without pre-immersion in citric acid (5 min, 0.3%, pH 3.8). Profilometry measured step-height enamel wear and surface microhardness at different depths was calculated using Vickers indentation at 0.1 N and 0.5 N loads. RESULTS: Dental material wear using the CAD/CAM antagonists showed consistency with previous data: mean (SD) resin-modified glass ionomer material loss of 177.77 (16.89) µm vs. 22.15 (1.30) µm fine particle hybrid composite resin wear vs. 13.63 (1.02) µm micro filled composite resin wear (P < 0.001). The coefficient of variation was less than 10%. Following validation, enamel sample wear was significantly increased when attrition was introduced (P < 0.001) independent of buccal vs. occlusal sample location (P < 0.05). Attrition resulted in occlusal wear of 26.1 ± 4.5 µm vs. buccal 26.3 ± 1.2 µm and attrition/erosion resulted in occlusal wear of 26.05 ± 4.46 µm vs. buccal 25.27 ± 1.16 µm. Whereas erosion-alone resulted in occlusal wear of 1.65 ± 0.13 µm and buccal 1.75 ± 0.03 µm. Microhardness testing at different loads revealed significantly greater hardness reductions in occlusal enamel vs. buccal enamel for 0.1 KgF indentations (P < 0.001) whereas in contrast 0.5 KgF indentations showed no differences. SIGNIFICANCE: Wear simulation with CAD/CAM glass ceramic antagonists produced consistent wear in dental materials and human enamel, regardless of enamel surface origin. Lighter (0.1 KgF) hardness testing of occlusal vs. buccal origin revealed damage to the mechanical integrity of the superficial worn enamel.

Tetracycline adsorption/desorption by raw and activated Tunisian clays.

Clay-based adsorbents have applications in environmental remediation, particularly in the removal of emerging pollutants such as antibiotics. Taking that into account, we studied the adsorption/desorption process of tetracycline (TC) using three raw and acid- or base-activated clays (AM, HJ1 and HJ2) collected, respectively, from Aleg (Mazzouna), El Haria (Jebess, Maknessy), and Chouabine (Jebess, Maknessy) formations, located in the Maknessy-Mazzouna basin, center-western of Tunisia. The main physicochemical properties of the clays were determined using standard procedures, where the studied clays presented a basic pH (8.39-9.08) and a high electrical conductivity (446-495 dS m-1). Their organic matter contents were also high (14-20%), as well as the values of the effective cation exchange capacity (80.65-97.45 cmolckg-1). In the exchange complex, the predominant cations were Na and Ca, in the case of clays HJ1 and AM, while Mg and Ca were dominant in the HJ2 clay. The sorption experimental setup consisted in performing batch tests, using 0.5 g of each clay sample, adding the selected TC concentrations, then carrying out quantification of the antibiotic by means of HPL-UV equipment. Raw clays showed high adsorption potential for TC (close to 100%) and very low desorption (generally less than 5%). This high adsorption capacity was also present in the clays after being activated with acid or base, allowing them to adsorb TC in a rather irreversible way for a wide range of pH (3.3-10) and electrical conductivity values (3.03-495 dS m-1). Adsorption experimental data were studied as regards their fitting to the Freundlich, Langmuir, Linear and Sips isotherms, being the Sips model the most appropriate to explain the adsorption of TC in these clays (natural or activated). These results could help to improve the overall knowledge on the application of new low-cost methods, using clay based adsorbents, to reduce risks due to emerging pollutants (and specifically TC) affecting the environment.

Evaluation of mechanical, optical, and fluoride-releasing properties of a translucent bulk fill glass hybrid restorative dental material.

OBJECTIVE: Measure and compare the mechanical properties, translucency, and fluoride-releasing capabilities of EQUIA Forte HT against Fuji IX GP and ChemFil Rock. MATERIALS AND METHODS: Ten specimens of each material were fabricated for compressive strength (CS), flexural strength (FS), and surface hardness analysis at 24 h and 7 days. The L*a*b* values were measured against a black-and-white background using a spectrophotometer to analyze the translucency parameter (TP). Fluoride release was recorded after 2 months of immersion in distilled water. The mean data was analyzed by 1- and 2-way ANOVA (α = 0.5). RESULTS: EQUIA Forte HT showed higher CS, surface hardness, and FS values (p < 0.05) compared with Fuji IX GIC, while no significant difference was found in FS values between EQUIA Forte HT and Chemfil Rock (p > 0.05). The EQUIA Forte HT exhibited significantly higher translucency in comparison to both ChemFil Rock (p < 0.001) and Fuji IX GICs (p < 0.05). An increase (p > 0.05) of fluoride release was observed for EQUIA Forte HT. CONCLUSION: The EQUIA Forte HT Glass-ionomer cements (GIC) offers enhanced translucency, improved strength, and enhanced fluoride-releasing properties compared to the traditionally used Fuji IX GIC and ChemFil Rock GICs. This material might have a wide range of clinical applications due to its improved strength and optical properties. CLINICAL SIGNIFICANCE: Glass-ionomer dental restorative materials possess unique advantageous characteristics. However, its poor mechanical and optical properties have typically limited its clinical applications. Efforts to improve these properties have resulted in enhanced GICs. EQUIA Forte HT GIC offers enhanced mechanical and optical properties with potential applications in posterior and anterior restorative procedures.