Dental composite resins are widely used in dental practice and are continually being developed in order to obtain better products. To gain full benefit from these materials, it is important for the clinician to understand their properties. The following is a review of the more common characteristics of composites in current use.
The most critical issues faced by the world nowadays is to provide the sustainability of consumption for energy and natural resources. Lignin is said to be one of the alternative new discoveries best-suited lignocellulosic biomass due to its low cost, sufficient availability and environmentally safe. The valuable properties exhibited by lignin can give broader applications usage such as in composite materials, wood industries, polymer composite industries, pharmaceutical and corrosion inhibitor industries. Many biomass wastes resources, isolation processes and treatments are undergoing development in order to enhance the producing new lignin-based materials on an industrial scale. Therefore, this review discussed on the current knowledge on the structure and chemistry of isolation of lignin from different sources using various common methods, its characterization, properties and its applications.
With the unique properties such as high surface area to volume ratio, stability, inertness, ease of functionalization, as well as novel optical, electrical, and magnetic behaviors, nanomaterials have a wide range of applications in various fields with the common types including nanotubes, dendrimers, quantum dots, and fullerenes. With the aim of providing useful insights to help future development of efficient and commercially viable technology for large-scale production, this review focused on the science and applications of inorganic and organic nanomaterials, emphasizing on their synthesis, processing, characterization, and applications on different fields. The applications of nanomaterials on imaging, cell and gene delivery, biosensor, cancer treatment, therapy, and others were discussed in depth. Last but not least, the future prospects and challenges in nanoscience and nanotechnology were also explored.
Olive fiber is a sustainable material as well as alternative biomass for extraction of nanocrystalline cellulose (NCC), which has been widely applied in various industries. In the present study, ONC-I, ONC-II, and ONC-III were extracted from olive stem fiber at different hydrolysis reaction times of 30 min, 45 min, and 60 min, respectively. The nanoparticle size was found gradually reducing from ONC-I (11.35 nm width, 168.28 nm length) to ONC-III (6.92 nm width, 124.16 nm length) due to the disintegration of cellulose fibrils. ONC-II and ONC-III possessed highly pure cellulose compartments and enhanced crystals structure. This study also showed that rigidity increased from ONC-I to ONC-II. ONC-III showed the highest crystallinity of 83.1 %, endowing it as a potentially reliable load-bearing agent. Moreover, ONC-III exhibited highest stable heat resistance among the chemically-isolated nanocellulose. We concluded that olive NCC could be promising materials for a variety of industrial applications in various fields.
In industrial application, immobilized lipase are typically not reused and served as industrial waste after a certain process is completed. The capacity on the reusability of the spent lipase is not well studied. This current study embarks on reusing the remaining lipase from the spent immobilized enzyme. Active lipases were recovered using a simple reverse micellar extraction (RME). RME is the extraction process of targeted biomolecules using an organic solvent and a surfactant. This method was the first attempt reported on the recovery of the lipase from the used immobilized lipase. RME of the spent lipase was done using the nonionic Triton X-100 surfactant and toluene. Various parameters were optimized to maximize the lipase recovery from the used immobilized lipase. The optimum forward extraction condition was 0.075 M KCl, and backward conditions were at 0.15 M Triton X-100/toluene (pH 6, 2 M KCl) with recovery of 66%. The extracted lipase was immobilized via simple adsorption into the ethanol pretreated carrier. The optimum conditions of immobilization resulted in 96% of the extracted lipase was reimmobilized. The reimmobilized lipase was incubated for 20 h in pH 6 buffer at 50 °C of water bath shaker. The reimmobilized lipase still had 27% residual activity after 18 h of incubation, which higher thermal stability compared to the free lipase. In conclusion, the free lipase was successfully extracted from the spent immobilized lipase and reimmobilized into the new support. It exhibited high thermal stability, and the reusability of the spent lipase will promote continued use of industrial lipase and reduce the cost of the manufacturing process.
Graphene and its derivative materials present high potential towards medical and biological applications, including drug delivery and bioimaging, due to their exceptional properties such as thermal conductivity and high specific surface area. The main focus of this work is to review the current development of graphene materials and the derivatives for biocompatible, bioimaging and drug delivery applications. Also, the synthesis methods with variation of graphene nanocomposites and the functionalisation will be further explained. For the graphene approaches, chemical vapour deposition (CVD) is the best-known technique to make high-quality graphene sheet by growth route with mass production. By considering the organic graphene nanocomposites, the biocompatibility and cytotoxic effects against graphene nanocomposites were evaluated for biomedical employments such as high quality bioimaging and effective drug delivery for cancer treatments. For example, graphene oxide incorporated with PEG and loaded with SN 38 for camptothecin analolgue as anticancer drug and revealed high cytotoxicity has an effect of 1000 times better effect than CPT in HCT-116 cells. Their drug delivery ability for both in-vivo and in-vitro applications compared to the controlled drugs such as doxorubicin (DOX) will be discussed accordingly. The graphene and its deriavatives possess some intriguing properties, which will lead to drug delivery due to strong biocompatibility and cyctotoxic effect towards biomedicine applications.
Silicon dioxide (SiO2) is the most widely used dielectric for electronic applications. It is usually produced by thermal oxidation of silicon or by using a wide range of vacuum-based techniques. By default, the growth of SiO2 by thermal oxidation of silicon requires the use of Si substrates whereas the other deposition techniques either produce low quality or poor interface material and mostly require high deposition or annealing temperatures. Recent investigations therefore have focused on the development of alternative deposition paradigms based on solutions. Here, we report the deposition of SiO2 thin film dielectrics deposited by spray pyrolysis in air at moderate temperatures of ≈350 °C from pentane-2,4-dione solutions of SiCl4. SiO2 dielectrics were investigated by means of UV-vis absorption spectroscopy, spectroscopic ellipsometry, XPS, XRD, UFM/AFM, admittance spectroscopy, and field-effect measurements. Data analysis reveals smooth (RRMS < 1 nm) amorphous films with a dielectric constant of about 3.8, an optical band gap of ≈8.1 eV, leakage current densities in the order of ≈10(-7) A/cm(2) at 1 MV/cm, and high dielectric strength in excess of 5 MV/cm. XPS measurements confirm the SiO2 stoichiometry and FTIR spectra reveal features related to SiO2 only. Thin film transistors implementing spray-coated SiO2 gate dielectrics and C60 and pentacene semiconducting channels exhibit excellent transport characteristics, i.e., negligible hysteresis, low leakage currents, high on/off current modulation ratio on the order of 10(6), and high carrier mobility.
A toxicity electrochemical DNA biosensor has been constructed for the detection of carcinogens using 24 base guanine DNA rich single stranded DNA, and methylene blue (MB) as the electroactive indicator. This amine terminated ssDNA was immobilized onto silica nanospheres and deposited on gold nanoparticle modified carbon-paste screen printed electrodes (SPEs). The modified SPE was initially exposed to a carcinogen, followed by immersion in methylene blue for an optimized duration. The biosensor response was measured using differential pulse voltammetry. The performance of the biosensor was identified on several anti-cancer compounds. The toxicity DNA biosensor demonstrated a linear response range to the cadmium chloride from 0.0005 ppm to 0.01 ppm (R2 = 0.928) with a limit of detection at 0.0004 ppm. The biosensor also exhibited its versatility to screen the carcinogenicity of potential anti-cancer compounds.
The sustainability of nitrile glove production process is essential both in the financial and energy perspective. Nitrile glove has the lowest material cost with positive mechanical and chemical performance quality for the disposable glove market. Nitrile glove also holds a major market in disposable gloves sector, and nitrile rubber compounds may contribute to the huge reduction of the capital cost for a pair of surgical gloves due to the inexpensive raw material compares with other synthetic polyisoprene or neoprene. Hence, blending of bio-additive into the nitrile latex might support the 3 pillars of sustainability for environmental, societal, and financial sector. Bio-additives helps increase the degradation rate of gloves under natural conditions. Bio-based substances could be derived from food waste, natural plants, and aquatic plants like micro- and macro algae. Furthermore, antimicrobial agent (e.g. brilliant green and cyclohexadiene) is the trend in surgical glove for coated as protecting layer, due to the capability to remove pathogens or bacterial on the surgeon hands during operation period. Besides, the section in energy recovery is a proposing gateway for reducing the financial cost and makes the process sustainable.
Garcinia mangostana pericarp is a good source of natural antioxidants with numerous functional properties. The conventional approaches for the recovery of antioxidants from Garcinia mangostana pericarp require long processing time and high temperature, which may cause degradation or loss of bioactivity of antioxidants, and often result in low recovery efficiency. In this study, the extraction of antioxidants from Garcinia mangostana pericarp was investigated using a polyethylene glycol (PEG)/citrate aqueous biphasic system (ABS) with the addition of surfactants. The optimum condition for the recovery of antioxidants was achieved in PEG 1000/citrate ABS of pH 8 with tie-line length (TLL) of 48.3% (w/w), volume ratio (VR) of 1.6, 0.2% (w/w) sample loading and addition of 1.0% (w/w) Tween 85. The antioxidants were recovered in the PEG-rich top phase with a high K value of 18.23 ± 0.33 and a recovery yield of 92.01% ± 0.09. The findings suggested that the addition of surfactants to polymer/salt ABS can enhance the recovery of antioxidants from Garcinia mangostana pericarps by conserving the antioxidative properties.
The performance of lysozyme adsorption by the aminated nanofiber membrane immobilized with Reactive Green 19 (RG19) dyes was evaluated in batch and flow systems. The physicochemical properties of the dye-immobilized nanofiber membrane were characterized. The parameters of batch-mode adsorption of lysozyme (e.g., pH, initial dye concentration, and lysozyme concentration) were optimized using the Taguchi method. In a flow process, the factors influencing the dynamic binding performance for lysozyme adsorption in the chicken egg white (CEW) solution include immobilized dye concentration, adsorption pH value, feed flow rate, and feed CEW concentration. The impact of these operating conditions on the lysozyme purification process was investigated. Under optimal conditions, the recovery yield and purification factor of lysozyme achieved from the one-step adsorption process were 98.52% and 143 folds, respectively. The dye-affinity nanofiber membrane also did not exhibit any significant loss in its binding capacity and purification performance after five consecutive uses.
The main objectives of this study are to synthesize a new solid-supported ionic liquid (SSIL) that has a covalent bond between the solid support, i.e., activated silica gel, with thiosalicylate-based ionic liquid and to evaluate the performance of this new SSIL as an extractant, labelled as Si-TS-SSIL, and to remove Pb(II) ions from an aqueous solution. In this study, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium thiosalicylate ([MTMSPI][TS]) ionic liquid was synthesized and the formation of [MTMSPI][TS] was confirmed through structural analysis using NMR, FTIR, IC, TGA, and Karl Fischer Titration. The [MTMSPI][TS] ionic liquid was then chemically immobilized on activated silica gel to produce a new thiosalicylate-based solid-supported ionic liquid (Si-TS-SSIL). The formation of these covalent bonds on Si-TS-SSIL was confirmed by solid-state NMR analysis. Meanwhile, BET analysis was performed to study the surface area of the activated silica gel and the prepared Si-TS-SSIL (before and after washing with solvent) with the purpose to show that all physically immobilized [MTMSPI][TS] has been washed off from Si-TS-SSIL, leaving only chemically immobilized [MTMSPI][TS] on Si-TS-SSIL before proceeding with removal study. The removal study of Pb(II) ions from an aqueous solution was carried out using Si-TS-SSIL as an extractant, whereby the amount of Pb(II) ions removed was determined by AAS. In this removal study, the experiments were carried out at a fixed agitation speed (400 rpm) and fixed amount of Si-TS-SSIL (0.25 g), with different contact times ranging from 2 to 250 min at room temperature. The maximum removal capacity was found to be 8.37 mg/g. The kinetics study was well fitted with the pseudo-second order model. Meanwhile, for the isotherm study, the removal process of Pb(II) ions was well described by the Freundlich isotherm model, as this model exhibited a higher correlation coefficient (R2), i.e., 0.99, as compared to the Langmuir isotherm model.
Herein, five N, S-co-doped carbocatalysts were prepared from different carbonaceous precursors, namely sawdust (SD), biochar (BC), carbon-nanotubes (CNTs), graphite (GP), and graphene oxide (GO) and compared. Generally, as the graphitization degree increased, the extent of N and S doping decreased, graphitic N configuration is preferred, and S configuration is unaltered. As peroxymonosulfate (PMS) activator for ciprofloxacin (CIP) removal, the catalytic performance was in order: NS-CNTs (0.037 min-1) > NS-BC (0.032 min-1) > NS-rGO (0.024 min-1) > NS-SD (0.010 min-1) > NS-GP (0.006 min-1), with the carbonaceous properties, rather than the heteroatoms content and textural properties, being the major factor affecting the catalytic performance. NS-CNTs was found to have the supreme catalytic activity due to its remarkable conductivity (3.38 S m-1) and defective sites (ID/IG = 1.28) with high anti-interference effect against organic and inorganic matter and varying water matrixes. The PMS activation pathway was dominated by singlet oxygen (1O2) generation and electron transfer regime between CIP and PMS activated complexes. The CIP degradation intermediates were identified, and a degradation pathway is proposed. Overall, this study provides a better understanding of the importance of selecting a suitable carbonaceous platform for heteroatoms doping to produce superior PMS activator for antibiotics decontamination.
The process parameters of microwave hydrothermal carbonization (MHTC) have significant effect on yield of hydrochar. This study discusses the effect of process parameters on hydrochar yield produced from MHTC of rice husk. Results revealed that, over the ranges tested, a lower temperature, lower reaction time, lower biomass to water ratio, and higher particle size produce more hydrochar. Maximum hydrochar yield of 62.8% was obtained at 1000 W, 220 °C, and 5 min. The higher heating value (HHV) was improved significantly from 6.80 MJ/kg of rice husk to 16.10 MJ/kg of hydrochar. Elemental analysis results showed that the carbon content increased and oxygen content decreased in hydrochar from 25.9 to 47.2% and 68.5 to 47.0%, respectively, improving the energy and combustion properties. SEM analysis exhibited modification in structure of rice husk and improvement in porosity after MHTC, which was further confirmed from BET surface analysis. The BET surface area increased from 25.0656 m2/g (rice husk) to 92.6832 m2/g (hydrochar). Thermal stability of hydrochar was improved from 340 °C for rice husk to 370 °C for hydrochar.
This review paper covers the major synthetic approaches attempted towards the synthesis of α-azido ketones, as well as the synthetic applications/consecutive reactions of α-azido ketones.
Goji berries (Lycium fruits) are usually found in Asia, particularly in northwest regions of China. Traditionally, dried goji berries are cooked before they are consumed. They are commonly used in Chinese soups and as herbal tea. Moreover, goji berries are used for the production of tincture, wine, and juice. Goji berries are high antioxidant potential fruits which alleviate oxidative stress to confer many health protective benefits such as preventing free radicals from damaging DNA, lipids, and proteins. Therefore, the aim of the review was to focus on the bioactive compounds and pharmacological properties of goji berries including their molecular mechanisms of action. The health benefits of goji berries include enhancing hemopoiesis, antiradiation, antiaging, anticancer, improvement of immunity, and antioxidation. There is a better protection through synergistic and additive effects in fruits and herbal products from a complex mixture of phytochemicals when compared to one single phytochemical.
Four previously undescribed alkaloids, aspergillinine A-D, and four known diterpene pyrones were isolated from the potato dextrose agar (PDA) culture of Aspergillus sp. HAB10R12. The chemical structures of the isolated compounds were elucidated based on a detailed analysis of their NMR and MS data. The absolute configuration of the isolated compounds was determined by Electronic Circular Dichroism analysis coupled with computational methods. Aspergillinine A represents the first example of a diketopiperazine dipeptide containing the unnatural amino acid N-methyl kynurenine. Its absolute configuration revealed that it adopts a rather unusual conformation. Aspergillinine B represents a previously unencountered skeleton containing an isoindolinone ring. Aspergillinine C and D were similar to previously isolated diketopiperazine alkaloids, namely, lumpidin and brevianamide F, respectively. The diterpene pyrones were isolated twice previously, once from a soil-derived Aspergillus species, and once from the liquid culture of Aspergillus sp. HAB10R12. The alkaloids isolated in this study showed no antiproliferative activity when tested against HepG2 and A549 cancer cell lines.
This work investigates the role of sintering temperature on bioactive glass-ceramics derived from the new composition CaO-P2O5-Na2O-B2O3-SiO2 glass system. The sintering behaviour of the samples' physical, structural, and mechanical properties is highlighted in this study. The experimental results indicated that the sintering process improved the crystallization and hardness of the final product. Results from XRD and FTIR showed the existence of carbonate apatite, pseudo-wollastonite, and wollastonite phases. From the results, the bioglass-ceramics sintered at 700 °C obtained the highest densification and optimum mechanical results. It had the value of 5.34 ± 0.21 GPa regarding microhardness and 2.99 ± 0.24 MPa m1/2 concerning fracture toughness, which falls in the range of the human enamel. Also, the sintered samples maintained their bioactivity and biodegradability after being tested in the PBS medium. The bioactivity does not affect but slows down the apatite formation rate. Overall results promoted the novel bioglass-ceramics as a candidate material for dental application.
Starch nanocrystals (SNCs) are tiny particles that possess unique qualities due to their small size, such as increased crystallinity, thin sheet structure, low permeability, and strong resistance to digestion. Although sago starch nanocrystals (SNCs) are naturally hydrophilic, their properties can be modified through chemical modifications to make them more versatile for various applications. In this study, the esterification process was used to modify SNCs using lauroyl chloride (LC) to enhance their surface properties. Three different ratios of LC to SNC were tested to determine the impact on the modified SNC (mSNC). The chemical changes in the mSNC were analyzed using FTIR and 1H NMR spectroscopy. ##The results showed that as the amount of LC increased, the degree of substitution (DS) also increased, which reduced the crystallinity of the mSNC and its thermal stability. However, the esterification process also improved the hydrophobicity of the SNC, making it more amphiphilic. The emulsification capabilities of the mSNC were investigated using a Pickering emulsion, and the results showed that the emulsion made from mSNC-1.0 had better stability than the one made from pristine SNC. This study highlights the potential of SNC as a particle emulsifier and demonstrates how esterification can improve its emulsification capabilities.
Rice bran protein concentrates (RBPC) were extracted using mild alkaline solvents (pH: 8, 9, 10). The physicochemical, thermal, functional, and structural aspects of freeze-drying (FD) and spray-drying (SD) were compared. FD and SD of RBPC had porous and grooved surfaces, with FD having non-collapsed plates and SD being spherical. Alkaline extraction increases FD's protein concentration and browning, whereas SD inhibits browning. According to amino acid profiling, RBPC-FD9's extraction optimizes and preserves amino acids. A tremendous particle size difference was prominent in FD, thermally stable at a minimal maximum of 92 °C. Increased pH extraction gives FD greater exposal surface hydrophobicity and positively relates to denaturation enthalpy. Mild pH extraction and drying significantly impacted solubility, improved emulsion properties, and foaming properties of RBPC as observed in acidic, neutral, and alkaline environments. RBPC-FD9 and RBPC-SD10 extracts exhibit outstanding foaming and emulsion activity in all pH conditions, respectively. Appropriate drying selection, RBPC-FD or SD potentially employed as foaming/emulsifier agent or meat analog.