Solid Powder Form Research Articles

Experimental studies on behavior of one-part geopolymer composite slabs subjected to blast loading

Over the past two decades, geopolymer has emerged as a noteworthy alternative to traditional cementitious materials in construction, offering comparable performance with reduced carbon dioxide emissions. The recent development of one-part geopolymer composites, which transform the alkaline activating solution into a solid powder form, has significantly enhanced the scalability and applicability of geopolymer in construction contexts. This study investigates the mechanical behavior of one-part geopolymer composite slabs when subjected to blast loading. Four slab specimens were constructed using the one-part geopolymer composite. Two of these specimens were reinforced with steel wire mesh, while the other two used PVA fibers for reinforcement. These slabs were tested under various blast loading induced by a shock tube. Employing three-dimensional digital image correlation techniques, the dynamic responses and damage mechanisms exhibited by these slabs were analyzed and discussed. The experimental results reveal that the fiber-reinforced geopolymer composite (FRGC) slabs demonstrate superior blast resistance compared to those reinforced with steel wire mesh. In particular, the one-part geopolymer matrix combined with PVA fibers exhibited a synergistic effect, indicating an enhanced capacity for energy dissipation. The findings suggest that one-part geopolymer concrete reinforced with PVA fibers holds significant potential for applications in the field of protective engineering, marking a step forward in the development of sustainable and resilient construction materials.

Two-dimensional metal–organic framework for post-synthetic immobilization of graphene quantum dots for photoluminescent sensing

Immobilization of graphene quantum dots (GQDs) on a solid support is crucial to prevent GQDs from aggregation in the form of solid powder and facilitate the separation and recycling of GQDs after use. Herein, spatially dispersed GQDs are post-synthetically coordinated within a two-dimensional (2D) and water-stable zirconium-based metal–organic framework (MOF). Unlike pristine GQDs, the obtained GQDs immobilized on 2D MOF sheets show photoluminescence in both suspension and dry powder. Chemical and photoluminescent stabilities of MOF-immobilized GQDs in water are investigated, and the use of immobilized GQDs in the photoluminescent detection of copper ions is demonstrated. Findings here shed the light on the use of 2D MOFs as a platform to further immobilize GQDs with various sizes and distinct chemical functionalities for a range of applications.

Analytical Method Development and Validation of Lycopene Present in Multivitamin Tablets

Lycopene is an organic compound belonging to tetraterpene and a carotene category. Lycopene is a brick red carotenoid hydrocarbon found in tomatoes and other red fruits and vegetables. Lycopene is extracted from red fruit & vegetables and found in two physical form Oily liquid & granular solid powder form. Lycopene is also used as supplement with multivitamin formulated as tablets. An RP-HPLC method was developed and validated for the Lycopene (Powder form or water suspendable form) in Multivitamin Tablets. The chromatographic system was equipped with C18 a stainless steel column 30 cm x 4.0 mm, packed with octadecylsilane chemically bonded to porous silica or ceramic micro particles (5µm) and wavelength set at 475 nm, in conjunction with a mobile phase of Methanol, Water and Tetrahydrofuran in the ratio of 66:4:30 % v/v at a flow rate of 1.5 ml/min. The retention time of Lycopene was found to be 6 min ±1 min. The separation was performed at ambient temperature. Linearity was observed in the concentration range of 80-120% with correlation coefficient 0.9999 and slope 75145.63 Percentage recovery obtained 99.06-101.83 %. The percentage Assay was found to be 100.25 to 102.61 %.The proposed method is precise, accurate, selective and rapid for the determination of lycopene (Powder form) in Multivitamin tablet. The proposed method is optimized and validated as per guidelines of WHO TRS 937 & the International Conference on Harmonization (ICH) guidelines.

From nanoscale to microscale hierarchical multifunctional nano borate bioactive glass for efficient wound healing

The unique biodegradation and mineralization properties of nanosized CO32−- containing hydroxyapatite (HCA)-coated BBG (nano-HCA@BG) make it a promising material for soft tissue repair. However, its single-function solid powder form makes it difficult to control drug release rates, limiting its potential in vivo application. To address this challenge, we designed a hierarchical multifunctional composite by incorporating gelatin with nano-HCA@BG loaded with AgNPs. The hierarchical composite achieved a high degree of structural fit from nanometer to micrometer scale, as demonstrated by structural characterization results. The composite showed improved encapsulation of nanodrug and controlled degradation, as confirmed by degradation and antimicrobial property results. Wound healing experiments in vivo revealed efficient encapsulation of nano-HCA@BG through specific combination of gelatin and nano-HCA@BG, leading to improved controlled degradation and biological activity of the glass. The study also developed a dynamic flowing drug loading method that integrated material preparation and drug loading, thus improving the efficiency of drug loading of the nano-HCA@BG. Overall, our study demonstrates a new method for the preparation of hierarchical functional biomaterials of bioglass, laying the foundation for nano-HCA@BG to play an important role in tissue repair. Moreover, our findings suggest that better understanding of the structure and biological properties of nano-HCA@BG could expand its application in other biomedical fields such as drug delivery.

COF-Based Electrodes with Vertically Supported Tentacle Array for Ultrahigh Stability Flexible Energy Storage

As an emerging porous crystal polymer, covalent organic frameworks (COFs) possess unique characteristics, such as high porosity, excellent stability, diverse topologies, designable open channels, and functional tunability. However, limited by the solid powder form, most COFs display low active site utilization and weak binding force with the current collector. In this pioneering research, we integrate redox-active COFs onto carbon fiber surfaces (AC-COFs) via strong covalent bridging. The 2,6-diaminoanthraquinone (DAAQ) pillars embedded on the carbon fiber surface are the key to precisely controlling the growth direction of COFs. The obtained tentacle-like array vertically supported on the surface of the carbon fiber can effectively induce charge transfer and prevent COFs from aggregating/collapsing. The strong covalent coupling and increase of accessible active sites contributed to the high specific capacitance of AC-COFs electrode (1034 mF cm-2). In addition, the COF-based flexible electrode retains an initial capacitance of 98% after 20000 charge-discharge cycles. The flexible all-solid-state symmetric supercapacitor is assembled by PVA/H2SO4 gel electrolyte with an areal capacitance of 715 mF cm-2. Besides, a red LED can be easily powered by three-bending AC-COFs//AC-COFs devices. The innovative synthesis strategy opens up new opportunities to develop high-performance flexible energy storage devices based on COFs.

Solubility Enhancement of Poorly Soluble Drug Ezetimibe by Developing Self Nano Emulsifying Drug Delivery System

Objectives: To enhance solubility, dissolution, and permeability of poorly water-soluble drug Ezetimibe (EZE) using a self-nano emulsifying drug delivery system (SNEDDS). Methods: Initially, the solubility of the EZE was determined in various oils and buffers. Surfactants and co-surfactants were screened based on the solubility of the drug in oil as per the emulsification efficacy test. Liquid SNEDDS was developed and characterized. Solid SNEDDS was developed and characterized using optimized liquid SNEDDS followed by the development of EZE-loaded Tablet SNEDDS. Finding: Liquid SNEDDS (LSNEDDS) was formulated using Capmul MCM C8 EP, Cremophore RH 40, and Labrafil M 2125 CS as oil, surfactant, and co-surfactant respectively. Optimized L-SNEDDS formulation was found to be efficient with an average %T of 99.5%, drug content of 98.43%, flask inversion 0 numbers, and the average particle size of 36.7 nm, zeta potential of -57.5 mV, Polydispersibility index in of 0.119. Also, the in vitro release profile of drug from L-SNEDDS encapsulated in hard gelatin capsules was evaluated in different dissolution media viz. simulated gastric fluid and simulated intestinal fluid. For the drug, more than 95% cumulative release was observed within 30 min exclusive of the pH of the medium. The L-SNEDDS were adsorbed on a solid support and then mixed with tablet blends and compressed into tablets. Further, no adverse changes in globule size, shape, the zeta potential of SNEDDS, and dissolution profile were apparent on conversion to solid powder form and tablet form. Novelty: The developed liquid SNEDDS form of EZE showed enhanced solubility, dissolution, and permeability in comparison to pure drugs. Conversion of L-SNEDDS to PSNEDDS would be a novel approach to overcome the limitations associatedwith liquid dosage forms. Keywords: Ezetimibe (EZE); Selfnano emulsifying drug delivery system (SNEDDS); liquid SNEDDS (L SNEDDS); powder SNEDDS (PSNEDDS); Tablet SNEDDS (TSNEDDS)

PH Auto-Sustain-Based Fermentation Supports Efficient Gamma-Aminobutyric Acid Production by Lactobacillus brevis CD0817

Gamma-aminobutyric acid (GABA) plays a role in several physiological functions. GABA production by lactic acid bacteria has attracted considerable interest; however, there is need to improve production. This study aimed to develop a pH auto-sustain (PAS)-based GABA fermentation process for Lactobacillus brevis CD0817, with L-glutamic acid (solubility ~6.0 g/L and isoelectric point 3.22) as the substrate. Firstly, we determined the optimum levels of vital factors affecting GABA synthesis using Erlenmeyer flask experiments. The results showed that optimal levels of sugar, yeast extract, Tween-80, manganese ion, and temperature were 5.0 g/L, 35.0 g/L, 1.0 g/L, 16.0 mg/L, and 30.0 °C, respectively. The added L-glutamic acid (650 g per liter of medium) mostly existed in the form of solid powder was slowly released to supply the substrate and acidity essential for GABA production with the progress of fermentation. Based on the optimizations, the PAS-based GABA fermentation was performed using a 10 L fermenter. The PAS-based strategy promoted GABA synthesis by the strain of up to 321.9 ± 6.7 g/L after 48 h, with a productivity of 6.71 g/L/h and a substrate molar conversion rate of 99.6%. The findings suggest that the PAS-based fermentation is a promising method for GABA production by lactic acid bacteria.

Continuous extraction of Spirulina platensis biopigments using different extraction sequences

The use of microalga Spirulina is developing rapidly in the industry. Spirulina biomass is widely used in the food, pharmaceutical and cosmeceutical industry because it is rich in biochemicals and antioxidants that are beneficial to human health. This study aimed to determine the biopigment contents in S. platensis and examine the sequences of continuous extraction process to obtain the optimal biopigment yields. Biopigments of S. platensis extracted in this study were total chlorophyll of 52.28 μg/mL (25.28 μg/mL chlorophyll a and 27 μg/mL chlorophyll b), total carotenoid of 7.9 μg/mL and phycocyanin of 0.020 mg/L. In addition to biopigments, a residue in the form of solid powder was also produced at 20.7 % of biomass. Simultaneous extraction of chlorophyll and total carotenoids was successfully applied in this study, while the optimal phycocyanin extraction should be further developed. The optimal extraction sequence of biopigments was extraction of chlorophyll then carotenoid with low heating and followed by extraction of phycocyanin.

Stability Study of Cannabidiol in the Form of Solid Powder and Sunflower Oil Solution.

Stability studies represent an essential component of pharmaceutical development, enabling critical evaluation of the therapeutic potential of an active pharmaceutical ingredient (API) or a final pharmaceutical product under the influence of various environmental factors. The aim of the present study was to investigate the chemical stability of cannabidiol (CBD) in the form of a solid powder (hereinafter referred to as CBD powder) and also dissolved in sunflower oil. We performed stress studies in accordance with the International Conference on Harmonization (ICH) guidelines, where 5 mg of marketed CBD in the form of a solid powder and in form of oil solution were exposed for 7 and 14, 30, 60, 90, 180, 270, and 365 days to precisely defined temperature and humidity conditions, 25 °C ± 2 °C/60% RH ± 5% and 40 °C ± 2 °C/75% RH ± 5% in both open and closed vials in the dark. CBD powder was significantly more stable than CBD in oil solution. Such finding is important because CBD is often administered dissolved in oil matrix in practice due to very good bioavailability. Thus, the knowledge on admissible shelf time is of paramount importance.

Ambidextrous Solid-state Magnetic Circularly Polarized Luminescence (MCPL) from Red-Green-Blue Inorganic Luminophores without Molecular Chirality

Herein, we report an example of red-green-blue full-color magnetic circularly polarized luminescence (MCPL) from three inorganic luminophores in their solid powder form and upon embedding in poly(m...

Acidic and enzymatic hydrolysis of glucomannan agroindustrial waste

Processing iles-iles tubers (Amorphophallus onchophyllus) into glucomannan flour leaves waste in the form of solid powder which is a by-product of the glucomannan separation process. The waste contains starch, fiber, and the remaining glucomannan which can still be used as simple sugar through hydrolysis. The purpose of this study is to examine the hydrolysis process of glucomannan agro-industrial waste using acidic and enzymatic methods as a comparison and to determine its effect on the products and by-products formed. Acid hydrolysis using conventional heating (autoclaves) and microwaves with dilute acids, HCl and H2SO4 at concentrations of 0.5 M and 1 M. Enzymatic hydrolysis using a consortium of α-amylase (1.75 and 3.5 U/g), amyloglucosidase (0.3 and 0.6 U/g), and cellulase (1 and 2 U/g). The results showed the potential of waste with the main components consisting of starch (47.26 ± 0.29%), fiber (15.79 ± 0.62%), residual glucomannan (12.64 ± 0.26%). Acid hydrolysis using HCl (0.40-0.56 g sugar/g dry matter) results slightly higher than H2SO4 (0.43-0.53 g sugar/g dry matter). Autoclaves hydrolysis produces sugars with a high DE (76.08-100.18), but with a lower yield (35.90-40.50 %), while the microwave hydrolysis produces sugars with a DP (1.62-2.22) and a higher yield. The higher the concentration of acid, the reducing sugar value, DE, and the higher HMF, but lower DP. In enzymatic hydrolysis, an increase in enzyme dose gives results that are not significantly different. The best treatment is obtained from enzymatic hydrolysis with normal doses because it has a reducing sugar (0.43 g reducing sugar/g dry matter) and total sugar (0.66 g sugar/g dry matter) high and a low HMF (0.19 mg HMF/g dry matter).

Synthesis and Characterization of MgO Doped ZnO Nanorods Prepared by Solution Immersion Method and their Effect on Energy Band Gap

In this research, solid powder form ZnO and MgO-doped ZnO were prepared by using solution immersion method. Mg divalent cation with different atomic percentage of 0.5%, 1.0% and 1.5% were added in 0.04 M of Zn2+ solution containing zinc nitrate hexahydrates as precursor and hexamethylene tetraamine as stabilizer. Annealing treatment was consequently carried out to transform the precursors into oxide forms. ZnO and MgO-doped ZnO were successfully obtained and the surface morphology, crystallite size and elemental composition were studied using Field Emission Scanning Electron Microscope (FESEM) and Energy dispersive X-Ray (EDX) respectively. The band gap energy was determined using Ultraviolet-Visible spectrophotometer (UV-Vis). FESEM images showed that the powder form of ZnO and MgO-doped ZnO consist of rod-like shape. A 0.5% of MgO-doped ZnO sample has smallest size of rods with higher aspect ratio compared to others. The EDX result revealed that the sample composed of Zn, O and Mg in the sample. The band gap energy for all samples was determined using Tauc plot and it was found that the band gap energy is reduced with 1.0 and 1.5 % doping while increased at 0.5% doping. The band gap energy was found to range between 3.23 eV to 3.26 eV. The 0.5% of Mg-doped ZnO with higher aspect ratio shows the highest band gap energy value.

Adsorption Studies of Zn (II) onto Nano- Biomaterials from Aqueous Media

Hydroxyapatite and β-tricalcium phosphate as a porous composites were prepared by a sol-gel process. We got a solid powder form composites as small particles. Mixed powder by ultrasonically dispersed throughout the aqueous solution containing an optimum amount of Ring-opening- polymerization was used for the preparation of a poly(d,l-lactide-co-glycolide Acid hydrogel polymer -functionalized polymer to appropriate for solid-phase extraction of metal ions from aqueous solutions. Resins were prepared by the copolymerization of the efficacious monomer. After the sol-gel process. Then, the nano-compound materials were used as absorbents to remove zinc ions from the aqueous solutions. The adsorption behaviors of nano-composites had been studied also. Experimental results revealed that the n-HAP/PLGA-β-TCP had greater adsorption capacity than nHAP/ β-TCP , and poly(d,l-lactide-co-glycolide Acid played vital role for the adsorption of Zinc ions. Moreover, the adsorption isotherms were applied by the two models Langmuir and Freundlich , The adsorption of metal ions can be explained the effect of composites recycle on the adsorption process on the cations by the Langmuir and Freundlich models effect and show the fitting of Zn(II) adsorption of correlation coefficient the Freundlich model is the best than Langmuir model

A comprehensive review of extrusion-based additive manufacturing processes for rapid production of metallic and ceramic parts

The extrusion-based additive manufacturing (EAM) technique is recently being employed for rapid production of metals and ceramic components. This technique involves extruding the metal or ceramic material in solid powder form mixed with a binder (i.e., an expendable viscous fluid), which is removed from the part after 3D printing. These technologies rely on the large design freedom allowed and the cost efficiency advantage over alternative metal additive manufacturing processes that are based on high energy beams, such as laser or electron beams. The EAM of metals and ceramics is not yet widespread, but published scientific and technical literature on it is rapidly growing. However, this literature is still less extensive than that on the fused deposition modeling (FDM) of plastics or the selective laser melting (SLM) of metals. This paper aims at filling this gap. FDM and powder injection molding are identified as preceding or enabling technologies for EAM. This paper systematically reviews all aspects of the feedstock EAM processes used for production of complex-shaped parts. The unique characteristics and advantages of these processes are also discussed with respect to materials and process steps. In addition, the key process parameters are explained to illustrate the suitability of the EAM process for diverse application domains.

Simple approach for the synthesis of Dy2Sn2O7 nanostructures as a hydrogen storage material from banana juice

In this experimental study, a new green and simple approach has been utilized to prepare nanostructured Dy2Sn2O7 as a remarkable material. It is the first report on the production of pure Dy2Sn2O7 nanostructures with utilizing banana juice as natural reagent as well as Dy3+ and Sn4+ sources. The effects of pressing the reactants within a pellet (in the solid form) and the use of banana in two different forms, in the form of solid powder or juice, as well as the applied amount of banana have been studied to achieve the condition for producing the sample with optimal morphology, purity and size. Various micro/nanostructures could be produced via changing the experimental condition. Based on the findings in this research, utilization of banana juice had remarkable role in Dy2Sn2O7 shape and size. Further, several analyses have been carried out to investigate the purity, porosity, composition and shape of the made samples. In following, for first time, the electrochemical hydrogen storage efficiency of Dy2Sn2O7 produced utilizing banana juice has been studied with chronopotentiometry method. The maximum discharge capacity of Dy2Sn2O7 that produced utilizing banana juice has been 4023 mA h/g after 20 cycles and this mesoporous sample demonstrated very good performance at room temperature. On the basis of the findings, the great discharge efficiency related to the green synthesized Dy2Sn2O7 nanostructures with utilization of banana juice can make them as competitive and desirable materials for hydrogen storage technology that they can bring about the diminution in the environmental contamination.

1,2,5-Triphenylpyrrole Derivatives with Dual Intense Photoluminescence in Both Solution and the Solid State: Solvatochromism and Polymorphic Luminescence Properties.

Five organic luminophores, 1,2,5-triphenylpyrrole (TPP) derivatives 3 a-e bearing electron-withdrawing or electron-donating groups, have been synthesized by Pd-catalyzed Suzuki coupling of 1-phenyl-2,5-di(4'-bromophenyl)pyrrole and para-substituted phenylboronic acid derivatives. They possess good thermal stabilities with high decomposition temperatures above 310 °C. Investigation of the photophysical properties of the luminogens 3 a-e indicated that they exhibited dual intense photoluminescence in both solution and the solid state due to their twisted conformations, and their fluorescence quantum yields (ΦF ) were determined as 68.7-94.9 % in THF solution and 19.1-52.0 % in solid powder form. Compounds 3 a-c bearing electron-accepting groups exhibited remarkable solvatochromism with large Stokes shifts, attributable to their D-π-A structure and intramolecular charge-transfer effect. In particular, 3 a, bearing aldehyde groups, displayed an obvious red-shift of the emission band from 445 to 564 nm with increasing solvent polarity. However, no obvious solvatochromic behavior was observed for compounds 3 d,e bearing electron-donating groups. The luminophore 3 a exhibited polymorphic luminescence properties and crystallization-induced emission enhancement.

Development and Characterization of Inorganic-Organic (Si-O-Al) Hybrid Geopolymeric Precursors via Solid State Method

In this study, an innovative one part, solution free concept applied for the development of hybrid inorganic–organic geopolymeric precursors having Si-O-Al networks at the precursor stage only. For the process development, fly ash, sodium hydroxide along with rice husk were together mechano-chemically dry grinded for a period of 8, 16 and 24 hours and ‘organic in-organic hybrid geopolymeric precursors’ in solid powder form is obtained. Mechanico-chemically derived tailored organic in-organic hybrid geopolymeric precursors were characterized by different techniques like XRD, 29Si MAS NMR, 27Al MAS NMR, SEM and FESEM. XRD results revealed presence of inorganic phases and organic phase in organic in-organic hybrid geopolymeric precursors. 29Si MAS NMR spectra revealed partial transformation of tertracoordinated Si into pentacoordinated silica due to presence of organic moiety.27Al MAS NMR spectra indicated presence of peaks centered at δ 52 to δ 66 ppm confirmed the formation of geopolymeric precursors. Developed geopolymeric precursor overcome the process drawbacks of conventional geopolymerization process via solution chemistry by making it user friendly as geopolymer from these geopolymeric precursor is obtained by addition of water only unlike conventional geopolymerization process which involves addition of hazardous alkaline solution to aluminosilicate raw material like fly ash. Further, the development of geopolymeric precursor utilize two environmentally unsafe waste materials and resulted in development of material with improved mechanical properties.

Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers

PurposeTechnological progress and high market demand contributed to a significant interest in the production of fertilizers based on humic acids. The aim of this study was to evaluate the possibilities of using humic acids obtained from lignite in the production of new commercial products. For this purpose, it is necessary to determine the quality standard requirements for such material. Properties of humic acids depend on source of origin as well as method of its extraction.Materials and methodsThe humic acids were extracted from polish deposit of lignite–Sieniawa Lubuska by alkaline extraction using for this purpose six kinds of extractants: 0.1 M NaOH and 0.25 M NaOH, 0.1 M KOH and 0.25 M KOH, and 0.1 M Na4P2O7 and 0.25 M Na4P2O7. The humic samples were used in solid powder form and characterized by UV-Vis spectroscopy, 13C NMR spectroscopy, fluorescence spectroscopy, and thermal analysis.Results and discussionThe determining factor influencing a degree of humic acids extraction from lignite and their structure is type of extractant. The largest efficiency of extraction (about 50%) was obtained with the use of NaOH solutions. All examined humic acids were generally characterized by simple and heterogeneous molecularly structure with low molecular weight and low aromatic polycondensation. Therefore, it can be concluded that humic acids extracted with NaOH and KOH solutions are less condensed than those extracted with Na4P2O7 solutions. It can suggest that humic acids obtained from lignite using solutions of Na4P2O7 are characterized by a low transformation degree and greater amount of carboxyl groups.ConclusionsLow rank coal can be successfully used in agriculture as a rich source of humic acids. Reagent used in their extraction, apart from high efficiency should have a neutral impact on their structure. Studies on the physicochemical properties of humic acids can be helpful in predicting behaviors of such fertilizer components in the environment and in inventing new products taking the principles of sustainable development into consideration.

Two Neutral Copper(I) Complexes Bearing 2‐(4‐Nitrophenyl) Imidazole[4,5‐f]‐1,10‐Phenanthroline: Synthesis, Crystal Structure, and Luminescence Properties

Two neutral copper(I) complexes (1 and 2) bearing deprotonated 2‐(4‐nitro phenyl) imidazole[4,5‐f]‐1,10‐phenanthroline (NPIP) and different phosphine ligands (bis[2‐(diphenylphosphino) phenyl]ether (DPEphos) and PPh3) were synthesized and characterized. The molecular structure of a representative complex (1) was established by single‐crystal X‐ray diffraction. The complex features the metal in a distorted tetrahedral environment surrounded by two N atoms of the chelating NPIP ligand and two P atoms from DPEphos ligand. The emission spectra show that the two complexes exhibit yellow emission both in anhydrous ether and in the solid powder form. Density functional theory (DFT) calculation was carried out at the B3LYP/6‐31G** level to determine the electronic transition within the molecule.

Designing of antibacterial plastics: thymol release from photocured thymol-doped acrylic resins

Antibacterial thymol-doped plastics can be prepared by photopolymerisation of solutions of thymol in tripropylenglycoldiacrylic monomer. The antibacterial properties of these doped plastics depend on the thymol release rate and this study reports results about the release of thymol from doped resin discs in different media under different conditions. Thymol-doped resin can release thymol in air, even though at a much slower rate than pure thymol in the form of solid powder. In particular. it has been found that the rate of release of thymol in air is mainly dependent on the temperature and on the thymol content in the resin. On the other hand, when a thymol-doped resin is put in contact with liquids, the rate of diffusion of thymol into surrounding liquids depends mainly on the chemical nature of the liquid, other than on the thymol concentration in the resin. In particular, the release is affected by the capability of the liquids to swell the resin and by the plasticizing effect of thymol. The release of thymol can be quantitatively described by a Weibull-type equation up to complete release of thymol.