Recent Advances of carbon Pathways for Sustainable Environment development.

Carbon dots (CDs) are an emerging type of carbon nanomaterial with strong biocompatibility, distinct chemical and physical properties, and low toxicity. CDs may emit fluorescence in the ultraviolet (UV) to near-infrared (NIR) range, which renders them beneficial for biomedical applications. CDs are usually made from carbon precursors and can be synthesized using top-down and bottom-up methods and it can be easily functionalized using different methods. For specific cases of biomedical applications carbon dot functionalization augments the materials' characteristics. Novel functionalization techniques are still being investigated. This review will look at the benefits of functionalization to attain a high yield and various biological applications. Biomedical applications such as photodynamic and photothermal therapy, biosensing, bioimaging, and antiviral and antibacterial properties will be covered in this review. The future applications of green synthesized carbon dots will be determined in part by this review.

Enhanced Lutetium Ion Sorption from Aqueous Solutions Using Activated Ion Exchangers.

The growing demand for rare earth elements (REE) requires the search for economically viable materials to efficiently recover REE from various solutions. Our research aims to investigate the potential of using a combination of the ion exchangers Lewatit CNP LF (in H+ form) and AV-17-8 (in OH- form) as an interpolymer system, "Lewatit CNP LF@AV-17-8" (X:Y), with varying mass ratios of X:Y to enhance the sorption efficiency of lutetium ions from nitrate solution. During the study, we used a range of analytical methodologies, including gravimetry, ultraviolet-visible (UV-VIS) spectroscopy, and inductively coupled plasma optical emission spectroscopy (ICP-OES). Our findings demonstrate that the interpolymer system "Lewatit CNP LF@AV-17-8" (X:Y), with a mass ratio of 4:2, exhibited a significantly enhanced sorption rate of Lu3+ ions (42%) compared to the individual Lewatit CNP LF (6:0) (25%) and the individual AV-17-8 (0:6) (21%) over a 48 h period. Moreover, this interpolymer system has demonstrated notable conformity to the Freundlich adsorption model, highlighting its performance as an effective sorbent for lutetium (III) ions. Notably, our study presents a novel utilization of the interpolymer system "Lewatit CNP LF@AV-17-8" (4:2), with an adsorption capacity of 221.05 mg/g, to enhance the recovery of lutetium ions. The research findings demonstrate its potential for enhancing the recovery of REE.

Multifunctional natural derived carbon quantum dots from Withania somnifera (L.) - Antiviral activities against SARS-CoV-2 pseudoviron.

Natural carbon dots (NCQDs) are expediently significant in the photo-, nano- and biomedical spheres owing to their facile synthesis, optical and physicochemical attributes. In the present study, three NCQDs are prepared and optimized from Withania somnifera (ASH) by one-step hydrothermal (bottom-up) method: HASHP (without dopant), nitrogen doped HASHNH3 (surface passivation using ammonia) and HASHEDA (surface passivation with ethylenediamine). The HR-TEM images reveal that HASHP, HASNH3, HASHEDA are spherically shaped with 2.5 ± 0.5 nm, 4 ± 1 nm and 5 ± 2 nm particle size, respectively, whereas FTIR confirms the aqueous solubility and nitrogen doping. The XRD patterns ensure that the NCQDs are amorphous and graphitic in nature. Comparatively, HASHNH3 (32.5%) and HASHEDA (27.6%) portray better fluorescence quantum yield than HASHP (5.6%). The increase in quantum yield for the doped NCQDs can be attributed to the surface passivation using ammonia and ethylenediamine. Surface passivation plays a crucial role in enhancing the fluorescence properties of quantum dots. The introduction of nitrogen through ammonia and ethylenediamine provides additional electronic states, possibly reducing non-radiative recombination sites and hence boosting the QY. In addition, an antiviral study unveils the striking potential of surface passivated NCQDs to curb Covid-19 crises with around 85% inhibition of SARS-CoV pseudoviron cells, which is better in comparison to the non-doped NCQDs. Hence, to understand the paramount efficacy of these NCQDs, a hypothesis on their possible mechanism of action against Covid-19 is discussed.

Biosynthesis, Characterization, and Antifungal Activity of Novel Trimetallic Copper Oxide-Selenium-Zinc Oxide Nanoparticles against Some Mucorales Fungi.

Metal nanoparticles are assumed to be a new generation of biologically active materials. The integrations between more than one metal are synergetic multifunctional features. In the current study, trimetallic copper-selenium-zinc oxide nanoparticles (Tri-CSZ NPs) were successfully mycosynthesized using Aspergillus niger through an ecofriendly method for the first time. The biosynthesis of the particles was characterized using physiochemical and topographical analysis. The physiochemical analysis included Fourier transform infrared spectroscopy (FTIR), which affirmed that the biosynthesis of Tri-CSZ NPs relies on the functional groups of fungal filtrates. Additionally, the UV-visible and X-ray diffraction patterns were proposed for the formation of Tri-CSZ NPs; moreover, topography analysis confirmed that the micromorphology of the nanoparticles were similar to a stick, with ends having a tetragonal pyramid shape, and with an average nanosize of about 26.3 ± 5.4 nm. Cytotoxicity results reveled that the Tri-CSZ NPs have no cytotoxicity on the human normal cell line Wi 38 at low concentrations, where the IC50 was 521 µg/mL. Furthermore, the antifungal activity of the Tri-CSZ NPs was evaluated. The antifungal results revealed that the Tri-CSZ NPs have promising antifungal activity against Mucor racemosus, Rhizopus microsporus, Lichtheimia corymbifera, and Syncephalastrum racemosum, where the minimum inhibitory concentrations (MICs) were 1.95, 7.81, 62.5, and 3.9 µg/mL, and the minimum fungicidal concentrations (MFCs) were 250, 62.5, 125, and 1000 µg/mL, respectively. In conclusion, Tri-CSZ NPs were successfully mycosynthesized using A. niger, which have a promising antifungal activity against fungi causing mucormycosis.

Nanoparticles: Taking a Unique Position in Medicine.

The human nature of curiosity, wonder, and ingenuity date back to the age of humankind. In parallel with our history of civilization, interest in scientific approaches to unravel mechanisms underlying natural phenomena has been developing. Recent years have witnessed unprecedented growth in research in the area of pharmaceuticals and medicine. The optimism that nanotechnology (NT) applied to medicine and drugs is taking serious steps to bring about significant advances in diagnosing, treating, and preventing disease-a shift from fantasy to reality. The growing interest in the future medical applications of NT leads to the emergence of a new field for nanomaterials (NMs) and biomedicine. In recent years, NMs have emerged as essential game players in modern medicine, with clinical applications ranging from contrast agents in imaging to carriers for drug and gene delivery into tumors. Indeed, there are instances where nanoparticles (NPs) enable analyses and therapies that cannot be performed otherwise. However, NPs also bring unique environmental and societal challenges, particularly concerning toxicity. Thus, clinical applications of NPs should be revisited, and a deep understanding of the effects of NPs from the pathophysiologic basis of a disease may bring more sophisticated diagnostic opportunities and yield more effective therapies and preventive features. Correspondingly, this review highlights the significant contributions of NPs to modern medicine and drug delivery systems. This study also attempted to glimpse the future impact of NT in medicine and pharmaceuticals.

3D printing of polylactic acid: recent advances and opportunities.

Bio-based polymers are a class of polymers made by living organisms, a few of them known and commercialized yet. Due to poor mechanical strength and economic constraints, they have not yet seen the extensive application. Instead, they have been an appropriate candidate for biological applications. Growing consumer knowledge of the environmental effect of polymers generated from petrochemical sources and a worldwide transition away from plastics with a lifespan of hundreds of years has resulted in greater interest in such hitherto unattainable sectors. Bio-based polymers come in various forms, including direct or "drop-in" replacements for their petrochemical counterparts with nearly identical properties or completely novel polymers that were previously unavailable, such as polylactide. Few of these bio-based polymers offer significantly improved technical specifications than their alternatives. Polylactic acid (PLA) has been well known in the last decade as a biodegradable thermoplastic source for use in 3DP by the "fused deposition modeling" method. The PLA market is anticipated to accomplish 5.2 billion US dollars in 2020 for its industrial usage. Conversely, 3DP is one of the emerging technologies with immense economic potential in numerous sectors where PLA is one of the critical options as the polymer source due to its environmentally friendly nature, glossiness, multicolor appearance, and ease of printing. The chemical structure, manufacturing techniques, standard features, and current market situation of PLA were examined in this study. This review looks at the process of 3DP that uses PLA filaments in extrusion-based 3DP technologies in particular. Several recent articles describing 3D-printed PLA items have been highlighted.

The Efficacious Benefit of 25-Hydroxy Vitamin D to Prevent COVID-19: An In-Silico Study Targeting SARS-CoV-2 Spike Protein.

The environment has rapidly looked at proven specialist task forces in the aftermath of the COVID-19 pandemic to build public health policies and measures to mitigate the effects of emerging coronaviruses. According to the researchers, taking 10 µg of 25-hydroxy vitamin D daily is recommended to keep us safe. There have been several studies recently indicating that there is a reduced risk of contracting Coronavirus by 25-hydroxy vitamin D consumption, even though there is no scientific data to prove that one would not affect the COVID-19 viral infection by 25-hydroxy vitamin D consumption. In this regard, the present study investigates the important literature and the role of 25-hydroxy vitamin D to prevent COVID-19 infection by conducting an in-silico study with SARS-CoV-2 spike protein as a target. Lopinavir, a previously reported drug candidate, served as a reference standard for the study. MD simulations were carried out to improve predictions of receptor-ligand complexes which offer novelty and strength to the current study. MD simulation protocols were explored and subjected to 25-hydroxy vitamin D and a known drug, Lopinavir. Comparison of ligands at refined models to the crystal structure led to promising results. Appropriate timescale simulations have been used to understand the activation mechanism, the role of water networks for receptor function, and the ligand binding process. Furthermore, MD simulations in combination with free energy calculations have also been carried out for lead optimization, evaluation of ligand binding modes, and assessment of ligand selectivity. From the results, 25-hydroxy vitamin D was discovered to have the vital interaction and highest potency in LBE, lower RMSD, and lower inhibition intensity similar to the standard. The findings from the current study suggested that 25-hydroxy vitamin D would be more effective in treating COVID-19. Compared with Lopinavir, 25-hydroxy vitamin D had the most potent interaction with the putative binding sites of the SARS-CoV-2 spike protein of COVID-19.

Divulging the anti-acetylcholinesterase activity of Colletotrichum lentis strain KU1 extract as sustainable AChE active site inhibitors.

Alzheimer's disease (AD), also called senile dementia is a neurodegenerative disease seen commonly in the elderly and is characterised by the formation of ß-amyloid plaques and neurofibrillary tangles (NFT). Though a complete understanding of the disease is lacking, recent studies showed the role of the enzyme acetylcholinesterase (AChE) in pathogenesis. Finding new lead compounds from natural sources has always been a quest for researchers. Endophytic fungi are a set of microbes that reside within plants without causing any harm. This study focuses on screening endophytes for the production of active acetylcholinesterase inhibitors. Five endophytic fungi were isolated from Catharanthus roseus and screened for AChE inhibitory activity. Three isolates were found to inhibit AChE inhibitory activity and were distinguished based on molecular and microscopic methods. The mycelial extract was taken for the bioassay-guided column chromatography and TLC was performed on the active fraction. The GC-MS and NMR analysis identified the active compounds in the extract as 9-hexadecen-1-ol and erucamide. Molecular docking studies revealed that the compounds are thermodynamically feasible and have significant glide scores. Computational studies revealed that the hydroxyl group of 9-hexadecen-1-ol forms a hydrogen bond with Ser 293 in the active site of AChE, whereas the active site interactions were predominantly hydrophobic in the case of erucamide and are reflected in AChE inhibition assays.

Mission impossible for cellular internalization: When porphyrin alliance with UiO-66-NH2 MOF gives the cell lines a ride.

Is it possible to accelerate cell internalization by hybridization of nanomaterials? Herein we support the realization of using metal-organic frameworks (MOFs) with the assistance of rigid porphyrin structure (H2TMP) aimed at drug loading, drug release, relative cell viability, and targeted in vitro drug delivery. There are several MOFs, i.e., UiO-66-NH2 (125 ± 12.5 nm), UiO-66-NH2 @H2TMP (160 ± 14 nm), UiO-66-NH2 @H2TMP@DOX, and UiO-66-NH2 @H2TMP@DOX@RO were synthesized and characterized applying HEK-293, HT-29, MCF-7, and MCF-10A cell lines. MTT investigations proved a significantly higher relative cell viability for H2TMP-aided leaf-extract-coated nanocarriers (above 62 % relative cell viability). Furthermore, the rigid H2TMP structure improved drug loading capacity by 24 % through an enhanced hydrogen bond, van der Waals, and π-π interactions. The in vitro targeted drug delivery experiments were conducted on HT-29 and MCF-7 cell lines. First, nanocarriers were treated with HT-29 cells, where UiO-66-NH2 @H2TMP@DOX@RO appeared as the best nanocarrier. Then, the selected nanocarrier was extracted from the HT-29 cell line and treated with the MCF-7 cell line. For the first time, the DOX remained inside the UiO-66-NH2 @H2TMP@DOX@RO after successful delivery to the HT-29 cell lines was observed on the MCF-7 cell line, and the second targeted drug delivery was performed. The results of this survey can enlighten the future ahead of cell internalization in MOF-based hybrid nanostructures.

Ground Tire Rubber Modified by Elastomers via Low-Temperature Extrusion Process: Physico-Mechanical Properties and Volatile Organic Emission Assessment.

In this paper, low-temperature extrusion of ground tire rubber was performed as a pro-ecological waste tires recycling method. During this process, ground tire rubber was modified with constant content of dicumyl peroxide and a variable amount of elastomer (in the range: 2.5-15 phr). During the studies, three types of elastomers were used: styrene-butadiene rubber, styrene-ethylene/butylene-styrene grafted with maleic anhydride and ethylene-octene copolymer. Energy consumption measurements, curing characteristics, physico-mechanical properties and volatile organic compounds emitted from modified reclaimed GTR were determined. The VOCs emission profile was investigated using a passive sampling technique, miniature emission chambers system and static headspace analysis and subsequently quantitative or qualitative analysis by gas chromatography. The VOCs analysis showed that in the studied conditions the most emitted volatile compounds are dicumyl peroxide decomposition by-products, such as: α-methylstyrene, acetophenone, α-cumyl alcohol, methyl cumyl ether, while the detection level of benzothiazole (devulcanization "marker") was very low. Moreover, it was found that the mechanical properties of the obtained materials significantly improved with a higher content of styrene-butadiene rubber and styrene-ethylene/butylene-styrene grafted with maleic anhydride while the opposite trend was observed for ethylene-octene copolymer content.

Extraction and optimization of Penicillium sclerotiorum strain AK-1 pigment for fabric dyeing.

Recently, the demand for fungal pigments has increased due to their several benefits over synthetic dyes. Many species of fungi are known to produce pigments and a large number of fungal strains for pigment production are yet to be extensively investigated. The natural pigment from sustainable natural sources has good economic and industrial value. Many synthetic colorants used in textile and various industries have many harmful effects on the human population and environment. Pigments and coloring agents may be extracted from a wide range of fungal species. These compounds are among the natural compounds having the most significant promise for medicinal, culinary, cosmetics, and textile applications. This study attempts to isolate and optimize the fermentation conditions of Penicillium sclerotiorum strain AK-1 for pigment production. A dark yellow-colored pigment was isolated from the strain with significant extractive value and antioxidant capacity. This study also identifies that the pigment does not have any cytotoxic effect and is multicomponent. The pigment production was optimized for the parameters such as pH, temperature, carbon and nitrogen source. Fabric dyeing experiments showed significant dyeing capacity of the pigment on cotton fabrics. Accordingly, the natural dye isolated from P. sclerotiorum strain AK-1 has a high potential for industrial-scale dyeing of cotton materials.

Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides.

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.

Identification of sustainable trypsin active-site inhibitors from Nigrospora sphaerica strain AVA-1.

Trypsin is a protein-digesting enzyme that is essential for the growth and regeneration of bone, muscle, cartilage, skin, and blood. The trypsin inhibitors have various role in diseases such as inflammation, Alzheimer's disease, pancreatitis, rheumatoid arthritis, cancer prognosis, metastasis and so forth. From 10 endophytic fungi isolated, we were able to screen only one strain with the required activity. The fungus with activity was obtained as an endophyte from Dendrophthoe falcata and was later identified as Nigrospora sphaerica. The activity was checked by enzyme assays using trypsin. The fungus was fermented and the metabolites were extracted and further purified by bioassay-guided chromatographic methods and the compound isolated was identified using gas chromatography-mass spectrometry. The compound was identified as quercetin. Docking studies were employed to study the interaction. The absorption, distribution, metabolism, and excretion analysis showed satisfactory results and the compound has no AMES and hepatotoxicity. This study reveals the ability of N. sphaerica to produce bioactive compound quercetin has been identified as a potential candidate for trypsin inhibition. The present communication describes the first report claiming that N. sphaerica strain AVA-1 can produce quercetin and it can be considered as a sustainable source of trypsin active-site inhibitors.

Bio-Based Polyurethane Networks Derived from Liquefied Sawdust.

The utilization of forestry waste resources in the production of polyurethane resins is a promising green alternative to the use of unsustainable resources. Liquefaction of wood-based biomass gives polyols with properties depending on the reagents used. In this article, the liquefaction of forestry wastes, including sawdust, in solvents such as glycerol and polyethylene glycol was investigated. The liquefaction process was carried out at temperatures of 120, 150, and 170 °C. The resulting bio-polyols were analyzed for process efficiency, hydroxyl number, water content, viscosity, and structural features using the Fourier transform infrared spectroscopy (FTIR). The optimum liquefaction temperature was 150 °C and the time of 6 h. Comprehensive analysis of polyol properties shows high biomass conversion and hydroxyl number in the range of 238-815 mg KOH/g. This may indicate that bio-polyols may be used as a potential substitute for petrochemical polyols. During polyurethane synthesis, materials with more than 80 wt% of bio-polyol were obtained. The materials were obtained by a one-step method by hot-pressing for 15 min at 100 °C and a pressure of 5 MPa with an NCO:OH ratio of 1:1 and 1.2:1. Dynamical-mechanical analysis (DMA) showed a high modulus of elasticity in the range of 62-839 MPa which depends on the reaction conditions.

Microstructure-Property Relationship of Polyurethane Foams Modified with Baltic Sea Biomass: Microcomputed Tomography vs. Scanning Electron Microscopy.

In this paper, novel rigid polyurethane foams modified with Baltic Sea biomass were compared with traditional petro-based polyurethane foam as reference sample. A special attention was focused on complex studies of microstructure, which was visualized and measured in 3D with high-resolution microcomputed tomography (microCT) and, as commonly applied for this purpose, scanning electron microscopy (SEM). The impact of pore volume, area, shape and orientation on appearance density and thermal insulation properties of polyurethane foams was determined. The results presented in the paper confirm that microcomputed tomography is a useful tool for relatively quick estimation of polyurethane foams' microstructure, what is crucial especially in the case of thermal insulation materials.

Natural carbon-based quantum dots and their applications in drug delivery: A review.

Natural carbon based quantum dots (NCDs) are an emerging class of nanomaterials in the carbon family. NCDs have gained immense acclamation among researchers because of their abundance, eco-friendly nature, aqueous solubility, the diverse functionality and biocompatibility when compared to other conventional carbon quantum dots (CDs).The presence of different functional groups on the surface of NCDs such as thiol, carboxyl, hydroxyl, etc., provides improved quantum yield, physicochemical and optical properties which promote bioimaging, sensing, and drug delivery. This review provides comprehensive knowledge about NCDs for drug delivery applications by outlining the source and rationale behind NCDs, different routes of synthesis of NCDs and the merits of adopting each method. Detailed information regarding the mechanism behind the optical properties, toxicological profile including biosafety and biodistribution of NCDs that are favourable for drug delivery are discussed. The drug delivery applications of NCDs particularly as sensing and real-time tracing probe, antimicrobial, anticancer, neurodegenerative agents are reviewed. The clinical aspects of NCDs are also reviewed as an initiative to strengthen the case of NCDs as potent drug delivery agents.

Kinetics of Cross-Linking Reaction of Epoxy Resin with Hydroxyapatite-Functionalized Layered Double Hydroxides.

The cure kinetics analysis of thermoset polymer composites gives useful information about their properties. In this work, two types of layered double hydroxide (LDH) consisting of Mg2+ and Zn2+ as divalent metal ions and CO32- as an anion intercalating agent were synthesized and functionalized with hydroxyapatite (HA) to make a potential thermal resistant nanocomposite. The curing potential of the synthesized nanoplatelets in the epoxy resin was then studied, both qualitatively and quantitatively, in terms of the Cure Index as well as using isoconversional methods, working on the basis of nonisothermal differential scanning calorimetry (DSC) data. Fourier transform infrared spectroscopy (FTIR) was used along with X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to characterize the obtained LDH structures. The FTIR band at 3542 cm-1 corresponded to the O-H stretching vibration of the interlayer water molecules, while the weak band observed at 1640 cm-1 was attributed to the bending vibration of the H-O of the interlayer water. The characteristic band of carbonated hydroxyapatite was observed at 1456 cm-1. In the XRD patterns, the well-defined (00l) reflections, i.e., (003), (006), and (110), supported LDH basal reflections. Nanocomposites prepared at 0.1 wt % were examined for curing potential by the Cure Index as a qualitative criterion that elucidated a Poor cure state for epoxy/LDH nanocomposites. Moreover, the curing kinetics parameters including the activation energy (Eα), reaction order, and the frequency factor were computed using the Friedman and Kissinger-Akahira-Sunose (KAS) isoconversional methods. The evolution of Eα confirmed the inhibitory role of the LDH in the crosslinking reactions. The average value of Eα for the neat epoxy was 54.37 kJ/mol based on the KAS method, whereas the average values were 59.94 and 59.05 kJ/mol for the epoxy containing Zn-Al-CO3-HA and Mg Zn-Al-CO3-HA, respectively. Overall, it was concluded that the developed LDH structures hindered the epoxy curing reactions.

Study on the Structure-Property Dependences of Rigid PUR-PIR Foams Obtained from Marine Biomass-Based Biopolyol.

The paper describes the preparation and characterization of rigid polyurethane-polyisocyanurate (PUR-PIR) foams obtained with biopolyol synthesized in the process of liquefaction of biomass from the Baltic Sea. The obtained foams differed in the content of biopolyol in polyol mixture (0-30 wt%) and the isocyanate index (IISO = 200, 250, and 300). The prepared foams were characterized in terms of processing parameters (processing times, synthesis temperature), physical (sol fraction content, apparent density) and chemical structure (Fourier transform infrared spectroscopy), microstructure (computer microtomography), as well as mechanical (compressive strength, dynamic mechanical analysis), and thermal properties (thermogravimetric analysis, thermal conductivity coefficient). The influence of biopolyol and IISO content on the above properties was determined. The addition of up to 30 wt% of biopolyol increased the reactivity of the polyol mixture, and the obtained foams showed enhanced mechanical, thermal, and insulating properties compared to foams prepared solely with petrochemical polyol. The addition of up to 30 wt% of biopolyol did not significantly affect the chemical structure and average cell size. With the increase in IISO, a slight decrease in processing times and mechanical properties was observed. As expected, foams with higher IISO exhibited a higher relative concentration of polyisocyanurate groups in their chemical structure, which was confirmed using principal component analysis (PCA).

Investigating the Impact of Curing System on Structure-Property Relationship of Natural Rubber Modified with Brewery By-Product and Ground Tire Rubber.

The application of wastes as a filler/reinforcement phase in polymers is a new strategy to modify the performance properties and reduce the price of biocomposites. The use of these fillers, coming from agricultural waste (cellulose/lignocellulose-based fillers) and waste rubbers, constitutes a method for the management of post-consumer waste. In this paper, highly-filled biocomposites based on natural rubber (NR) and ground tire rubber (GTR)/brewers' spent grain (BSG) hybrid reinforcements, were prepared using two different curing systems: (i) sulfur-based and (ii) dicumyl peroxide (DCP). The influence of the amount of fillers (in 100/0, 50/50, and 0/100 ratios in parts per hundred of rubber) and type of curing system on the final properties of biocomposites was evaluated by the oscillating disc rheometer, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, swelling behavior, tensile testing, and impedance tube measurements. The results show, that the scorch time and the optimum curing time values of sulfur cured biocomposites are affected by the change of the hybrid filler ratio while using the DCP curing system, and the obtained values do not show significant variations. The results conclude that the biocomposites cured with sulfur have better physico-mechanical and acoustic absorption, and that the type of curing system does not influence their thermal stability. The overall analysis indicates that the difference in final properties of highly filled biocomposites cured with two different systems is mainly affected by the: (i) cross-linking efficiency, (ii) partial absorption and reactions between fillers and used additives, and (iii) affinity of additives to applied fillers.

Preparation, characterization and antimicrobial activity of polyvinyl alcohol/gum arabic/chitosan composite films incorporated with black pepper essential oil and ginger essential oil.

Natural materials have attracted increasing attention in wound dressing and food packaging process, which could overcome the serious environmental issues caused by conventional synthetic materials. Essential oils (EOs) such as black pepper essential oil (BPEO) and ginger essential oil (GEO) have extensively been reported for their nutritional and biomedical properties. In this study, biocomposite films based on polyvinyl alcohol (PVA), gum arabic (GA) and chitosan (CS) incorporated with BPEO and GEO were fabricated by solvent casting method. FTIR, XRD, SEM and DSC were performed with mechanical and antimicrobial properties of PVA/GA/CS films with and without BPEO and GEO. The BPEO-PVA/GA/CS film showed heterogeneous rough surface with cavities containing entrapment of BPEO droplets, whereas, the GEO-PVA/GA/CS film showed heterogeneous rough surface with coarseness due to the incorporation of respective EOs. The BPEO and GEO incorporated PVA/GA/CS films were considerable resistant to breakage and flexible with improved heat stability. The BPEO and GEO incorporated PVA/GA/CS films were significantly inhibited the growth of Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. The obtained results have demonstrated that both BPEO and GEO incorporated PVA/GA/CS films are promising alternatives to wound dressing and food packaging materials.