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Proceedings of the National Academy of... Apr 2022Knowledge of deformation mechanisms in aragonite, one of the three crystalline polymorphs of CaCO3, is essential to understand the overall excellent mechanical...
Knowledge of deformation mechanisms in aragonite, one of the three crystalline polymorphs of CaCO3, is essential to understand the overall excellent mechanical performance of nacres. Dislocation slip and deformation twinning were claimed previously as plasticity carriers in aragonite, but crystallographic features of dislocations and twins have been poorly understood. Here, utilizing various transmission electron microscopy techniques, we reveal the atomic structures of twins, partial dislocations, and associated stacking faults. Combining a topological model and density functional theory calculations, we identify complete twin elements, characters of twinning disconnection, and the corresponding twin shear angle (∼8.8°) and rationalize unique partial dislocations as well. Additionally, we reveal an unreported potential energy dissipation mode within aragonite, namely, the formation of nanograins via the pile-up of partial dislocations. Based on the microstructural comparisons of biogenic and abiotic aragonite, we find that the crystallographic features of twins are the same. However, the twin density is much lower in abiotic aragonite due to the vastly different crystallization conditions, which in turn are likely due to the absence of organics, high temperature and pressure differences, the variation in inorganic impurities, or a combination thereof. Our findings enrich the knowledge of intrinsic crystal defects that accommodate plastic deformation in aragonite and provide insights into designing bioengineering materials with better strength and toughness.
PubMed: 35357967
DOI: 10.1073/pnas.2122218119 -
Science and Technology of Advanced... Apr 2014Organic field-effect transistors (OFETs) are fundamental building blocks for various state-of-the-art electronic devices. Solution-processed organic crystals are... (Review)
Review
Organic field-effect transistors (OFETs) are fundamental building blocks for various state-of-the-art electronic devices. Solution-processed organic crystals are appreciable materials for these applications because they facilitate large-scale, low-cost fabrication of devices with high performance. Patterning organic crystal transistors into well-defined geometric features is necessary to develop these crystals into practical semiconductors. This review provides an update on recentdevelopment in patterning technology for solution-processed organic crystals and their applications in field-effect transistors. Typical demonstrations are discussed and examined. In particular, our latest research progress on the spin-coating technique from mixture solutions is presented as a promising method to efficiently produce large organic semiconducting crystals on various substrates for high-performance OFETs. This solution-based process also has other excellent advantages, such as phase separation for self-assembled interfaces via one-step spin-coating, self-flattening of rough interfaces, and purification that eliminates the impurity influences. Furthermore, recommendations for future perspectives are presented, and key issues for further development are discussed.
PubMed: 27877656
DOI: 10.1088/1468-6996/15/2/024203 -
Materials (Basel, Switzerland) Jun 2023Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps...
Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps can lead to a decrease in charge carrier mobility and an increase in recombination rates, thereby ultimately affecting the overall performance of the device. It is therefore important to understand and mitigate the impact of traps on organic semiconductor devices. In this contribution, the influence of the capture and release times of trap states, recombination rates, and the Lorentz force on the net charge of a low-mobility organic semiconductor was determined using the finite element method (FEM) and Hall effect method through numerical simulations. The findings suggest that increasing magnetic fields had a lesser impact on net charge at constant capture and release times of trap states. On the other hand, by increasing the capture time of trap states at a constant magnetic field and fixed release time, the net charge extracted from the semiconductor device increased with increasing capture time. Moreover, the net charge extracted from the semiconductor device was nearly four and eight times greater in the case of the non-Langevin recombination rates of 0.01 and 0.001, respectively, when compared to the Langevin rate. These results imply that the non-Langevin recombination rate can significantly enhance the performance of semiconductor devices, particularly in applications that require efficient charge extraction. These findings pave the way for the development of more efficient and cost-effective electronic devices with improved charge transport properties and higher power conversion efficiencies, thus further opening up new avenues for research and innovation in this area of modern semiconductor technology.
PubMed: 37445005
DOI: 10.3390/ma16134691 -
Polymers Aug 2023The safety of a medicinal product is determined by its pharmacological and toxicological profile, which depends not only on the active substance's toxicological... (Review)
Review
The safety of a medicinal product is determined by its pharmacological and toxicological profile, which depends not only on the active substance's toxicological properties, but also on the impurities it contains. Because impurities are a problem that must be considered to ensure the safety of a drug product, many studies have been conducted regarding the separation or purification of active pharmaceutical ingredients (APIs) and the determination of impurities in APIs and drug products. Several studies have applied molecularly imprinted polymers (MIPs) to separate impurities in active ingredients and as adsorbents in the sample preparation process. This review presents the design of MIPs and the methods used to synthesise MIPs to separate impurities in APIs and drug product samples, the application of MIPs to separate impurities, and a view of future studies involving MIPs to remove impurities from pharmaceutical products. Based on a comparison of the bulk and surface-imprinting polymerisation methods, the MIPs produced by the surface-imprinting polymerisation method have a higher adsorption capacity and faster adsorption kinetics than the MIPs produced by the bulk polymerisation method. However, the application of MIPs in the analysis of APIs and drug products are currently only related to organic compounds. Considering the advantages of MIPs to separate impurities, MIPs for other impurities still need to be developed, including multi-template MIPs for simultaneous separation of multiple impurities.
PubMed: 37631457
DOI: 10.3390/polym15163401 -
Regulatory Toxicology and Pharmacology... Feb 2015Stringent requirements are in place for the evaluation and registration of new compounds with biocidal or pesticidal activities. However, the registration requirements... (Comparative Study)
Comparative Study
Stringent requirements are in place for the evaluation and registration of new compounds with biocidal or pesticidal activities. However, the registration requirements for established compounds from new suppliers or for established compounds produced by a different manufacturing process have been less clear and ambiguity exists as to how 'equivalence of health hazards' can unequivocally be demonstrated analytically and by toxicological assays. The case presented in this analysis focuses on the chiral pyrethroid transfluthrin (TFL) synthesized by esterification of an acid chloride and alcoholic moiety. According to any modifications of the process of synthesis and purification, new potentially highly toxic and yet chemically reactive impurities in low concentrations (<0.1%) may be formed. Amongst these, that with the structural alert 'organic acid anhydride' was given heightened concern as the most potent putative toxicologically significant impurity. The course taken in this analysis focused on the comparison of reference TFL with commercialized generic TFL from two alternative manufacturing sources in India and China. Despite their apparent high racemic purity, TFLs from generic sources were biologically less effective, genotoxic in the Ames' assay, demonstrated sensory lung irritation and lung/skin sensitization in specialized bioassays. While the off-patent reference TFL was unequivocally negative in all assays (anhydride content not detectable, LOQ <0.01%), positive results with high batch-to-batch variability were a frequent outcome in generic TFLs. Tier I analytical assays failed to detect this relevant impurity in the absence of impurity-specific optimized analytical procedures. This finding suggests that a well-balanced combined approach of analytical and toxicological assays provides the best means to assure that all critical impurities are identified and accounted for. Similarly, putative 'structural alert'-based toxicity tests proved to be more predictive than any indiscriminant battery of standard bioassays commonly applied to demonstrate equivalence, such as acute oral/dermal toxicity and/or eye/skin irritation assays.
Topics: Administration, Inhalation; Animals; Chemical Industry; China; Culicidae; Cyclopropanes; Dermatitis, Allergic Contact; Fluorobenzenes; Germany; Guinea Pigs; India; Irritants; Male; Pesticides; Rabbits; Rats, Wistar; Respiratory Hypersensitivity; Toxicity Tests
PubMed: 25448443
DOI: 10.1016/j.yrtph.2014.11.003 -
Biophysical Reviews Oct 2023In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims... (Review)
Review
In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.
PubMed: 37975005
DOI: 10.1007/s12551-023-01146-6 -
PloS One 2020Saponins are secondary metabolites from plants added to shampoos and beverages to make them foam, and the sapogenins released from them upon acid hydrolysis are commonly...
BACKGROUND
Saponins are secondary metabolites from plants added to shampoos and beverages to make them foam, and the sapogenins released from them upon acid hydrolysis are commonly used as starting materials for steroidal drugs. However, current methods embed the saponin in a thick "gum" material consisting of multiple impurities. This gum limits access to the saponin, reducing the efficiency of hydrolysis and requiring large amounts of heat, organic solvents and effort to recover the sapogenin. For centuries, herbalists have been making tinctures by soaking plant materials at room temperature, in mixtures of alcohol and water. Many herbal tinctures contain saponins floating freely in solution, gum free. The saponin from sarsaparilla (Smilax spp), sarsasaponin, yields the sapogenin, sarsasapogenin, upon acid hydrolysis. The retail price of sarsasapogenin is very high but would be lower if the "gum problem" could be avoided.
MATERIALS AND METHODS
We incubated sarsaparilla tincture under different conditions of temperature, acidity and duration then used quantitative nuclear magnetic resonance (qNMR) to measure the amount of sarsasapogenin produced by hydrolysis as well as the amount of its epimer, smilagenin.
RESULTS AND DISCUSSION
Most, if not all the sarsasaponin in sarsaparilla root powder is extracted into a solution of 45% ethanol (55% water) at room temperature and stays suspended without formation of any particles (gum). Acid hydrolysis of the saponin in this solution is very efficient, approaching 100%. The sarsasapogenin released by hydrolysis and the smilagenin produced by its epimerisation, migrate into the chloroform phase.
CONCLUSION
Sarsaparilla saponin diffuses into and disperses in a solution of alcohol:water (45:55) at room temperature. Hydrolysis of saponins in tincture provides a simple, inexpensive and environmentally friendly alternative.
Topics: Acids; Hydrolysis; Plant Roots; Sapogenins; Saponins; Secondary Metabolism; Smilax
PubMed: 33382809
DOI: 10.1371/journal.pone.0244654 -
Environmental Chemistry Letters 2021Silica nanoparticles have rapidly found applications in medicine, supercapacitors, batteries, optical fibers and concrete materials, because silica nanoparticles have... (Review)
Review
Silica nanoparticles have rapidly found applications in medicine, supercapacitors, batteries, optical fibers and concrete materials, because silica nanoparticles have tunable physical, chemical, optical and mechanical properties. In most applications, high-purity silica comes from synthetic organic precursors, yet this approach could be costly, polluting and non-biocompatible. Alternatively, natural silica sources from biomass are often cheap and abundant, yet they contain impurities. Silica can be extracted from corn cob, coffee husk, rice husk, sugarcane bagasse and wheat husk wastes, which are often disposed of in rivers, lands and ponds. These wastes can be used to prepare homogenous silica nanoparticles. Here we review properties, preparation and applications of silica nanoparticles. Preparation includes chemical and biomass methods. Applications include biosensors, bioimaging, drug delivery and supercapacitors. In particular, to fight the COVID-19 pandemic, recent research has shown that silver nanocluster/silica deposited on a mask reduces SARS-Cov-2 infectivity to zero.
PubMed: 33199978
DOI: 10.1007/s10311-020-01123-5 -
Se Pu = Chinese Journal of... Apr 2021Istradefylline is a novel selective adenosine A receptor antagonist that is used to treat Parkinson's disease and improve motor dysfunction in the early stage of this...
Istradefylline is a novel selective adenosine A receptor antagonist that is used to treat Parkinson's disease and improve motor dysfunction in the early stage of this disease. During the synthesis of intermediate A1 (6-amino-1,3-diethyl-2,4-(1,3)-pyrimidinedione), at least two by-products were formed under alkaline or high-temperature conditions. In a previous study, one of the by-products in the synthesis of the intermediate was studied, and its structure was identified as ()-ethyl-2-cyano-3-ethylamino-2-butene amide. In this study, we used high performance liquid chromatography (HPLC) to analyze another impurity formed during the synthesis of A1, and the following steps were executed: 0.4 g of intermediate was weighed and added to a 50 mL beaker, followed by the sequential addition of 8 mL water and 8 mL acetonitrile, and then, ultrasonic dissolution was performed. Finally, the solution was filtered through a 0.45-μm organic membrane and the test sample solution was obtained. We used the Agilent zorbax C18 chromatography column, with acetonitrile (A)/water(B) as the mobile phase under gradient elution ((/A∶B)=/20∶80, /60∶40, -/90∶10). The detector wavelength is 268 nm. In order to separate the impurity from A1, we used a Ceres B preparative column, with acetonitrile-water (30/70, v/v) as the mobile phase. The flow rate was set at 30 mL/min, and the detection wavelength was 268 nm. The structure of the impurity was confirmed by high-resolution mass spectrometry (HRMS), one-dimensional nuclear magnetic resonance (NMR), and two-dimensional nuclear magnetic resonance (2D NMR), and characterized by single-crystal X-ray diffraction (XRD). In MS experiments, an electrospray ionization (ESI) source was used with positive ion scanning. In the NMR experiments, we used tetramethylsilane (TMS) as the internal standard and deuterated dimethyl sulfoxide (DMSO-d) as the solvent to obtain the spectra. The results of preparative high performance liquid chromatography (Prep-HPLC) showed that good separation effect could be achieved by isocratic elution, and the impurity was perfectly separated. TheH-NMR spectral data are as follows:H-NMR (600 MHz, DMSO): 1.01 (q, =6.9 Hz, 3H), 1.02 (q, =6.9 Hz, 3H), 1.07 (t, =6.9 Hz, 3H), 3.04 (p, =6.8 Hz, 2H), 3.74 (q, =7.0 Hz, 2H), 3.94 (q, =7.1 Hz, 2H), 5.85 (s, 1H). The C-NMR spectral data are summarized as follows: C-NMR (150 MHz, DMSO): 13.9, 14.1, 15.9, 34.6, 34.9, 36.9, 81.9, 152.2, 153.3, 159.3, 162.0. The impurity was characterized by single-crystal XRD, and its spatial structure was further verified and determined as 1-(1,3-diethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)-3-ethylurea. Based on the chemical structure of the impurity, we propose the following mechanism for the impurity: when A1 is synthesized under alkaline conditions or at high temperature, excessive diethylurea continues to undergo amidation with A1 to obtain this by-product. Although the formation mechanism of the impurity studied in this paper is different from that of the intermediate A1 impurity ()-ethyl-2-cyano-3-ethylamino-2-butene amide, both the impurities are formed at high temperatures. Both will be accompanied by A1 in the subsequent reaction of istradefylline synthesis. The relationship between drug impurities and drug safety is a complex relationship that is affected by many factors. Generally, most impurities in drugs have potential biological activities, and some even interact with the drugs, thus affecting their efficacy and safety and inducing toxic effects. Therefore, to ensure the quality of istradefylline, it is necessary to control the impurity content during the production. The findings of this paper may provide guidelines for controlling the impurity content in istradefylline.
Topics: Chromatography, High Pressure Liquid; Drug Contamination; Mass Spectrometry; Purines
PubMed: 34227764
DOI: 10.3724/SP.J.1123.2020.10013 -
Nano-micro Letters Aug 2022The complete elimination of methylammonium (MA) cations in Sn-Pb composites can extend their light and thermal stabilities. Unfortunately, MA-free Sn-Pb alloyed...
The complete elimination of methylammonium (MA) cations in Sn-Pb composites can extend their light and thermal stabilities. Unfortunately, MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization, due to the coexistence of mixed intermediate phases. Here, we report an additive strategy for finely regulating the impurities in the intermediate phase of CsFAPbSnI and, thereby, obtaining high-performance solar cells. We introduced d-homoserine lactone hydrochloride (D-HLH) to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors, thereby weakening the incomplete complexation effect between polar aprotic solvents (e.g., DMSO) and organic (FAI) or inorganic (CsI, PbI, and SnI) components, and balancing their nucleation processes. This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal annealing. Besides, this D-HLH substantially inhibited the oxidation of Sn species. This strategy generated a record efficiency of 21.61%, with a V of 0.88 V for an MA-free Sn-Pb device, and an efficiency of 23.82% for its tandem device. The unencapsulated devices displayed impressive thermal stability at 85 °C for 300 h and much improved continuous operation stability at MPP for 120 h.
PubMed: 35974239
DOI: 10.1007/s40820-022-00918-1