bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulation of the Blood–Brain Barrier for Drug Delivery to Brain
Authors: Han Liang
Published: December 2021

The blood–brain barrier (BBB) precisely controls brain microenvironment and neural activity by regulating substance transport into and out of the brain. However, it severely hinders drug entry into the brain, and the efficiency of various systemic therapies against brain diseases. Modulation of the BBB via opening tight junctions, inhibiting active efflux and/or enhancing transcytosis, possesses the potential to increase BBB permeability and improve intracranial drug concentrations and systemic therapeutic efficiency. Various strategies of BBB modulation have been reported and investigated preclinically and/or clinically. This review describes conventional and emerging BBB modulation strategies and related mechanisms, and safety issues according to BBB structures and functions, to try to give more promising directions for designing more reasonable preclinical and clinical studies.
Nanotechnology for Age-Related Macular Degeneration
Authors: Yang Bo , Li Ge , Liu Jiaxin , Li Xiangyu , Zhang Shixin , Sun Fengying , Liu Wenhua
Published: December 2021

Age-related macular degeneration (AMD) is a degenerative eye disease that is the leading cause of irreversible vision loss in people 50 years and older. Today, the most common treatment for AMD involves repeated intravitreal injections of anti-vascular endothelial growth factor (VEGF) drugs. However, the existing expensive therapies not only cannot cure this disease, they also produce a variety of side effects. For example, the number of injections increases the cumulative risk of endophthalmitis and other complications. Today, a single intravitreal injection of gene therapy products can greatly reduce the burden of treatment and improve visual effects. In addition, the latest innovations in nanotherapy provide the best drug delivery alternative for the treatment of AMD. In this review, we discuss the development of nano-drug delivery systems and gene therapy strategies for AMD in recent years. In addition, we discuss some novel targeting strategies and the potential application of these delivery methods in the treatment of AMD. Finally, we also propose that the combination of CRISPR/Cas9 technology with a new non-viral delivery system may be promising as a therapeutic strategy for the treatment of AMD.
Polymeric Nanoparticles Properties and Brain Delivery
Authors: Ribovski Laís , Hamelmann Naomi M. , Paulusse Jos M. J.
Published: December 2021

Safe and reliable entry to the brain is essential for successful diagnosis and treatment of diseases, but it still poses major challenges. As a result, many therapeutic approaches to treating disorders associated with the central nervous system (CNS) still only show limited success. Nano-sized systems are being explored as drug carriers and show great improvements in the delivery of many therapeutics. The systemic delivery of nanoparticles (NPs) or nanocarriers (NCs) to the brain involves reaching the neurovascular unit (NVU), being transported across the blood–brain barrier, (BBB) and accumulating in the brain. Each of these steps can benefit from specifically controlled properties of NPs. Here, we discuss how brain delivery by NPs can benefit from careful design of the NP properties. Properties such as size, charge, shape, and ligand functionalization are commonly addressed in the literature; however, properties such as ligand density, linker length, avidity, protein corona, and stiffness are insufficiently discussed. This is unfortunate since they present great value against multiple barriers encountered by the NPs before reaching the brain, particularly the BBB. We further highlight important examples utilizing targeting ligands and how functionalization parameters, e.g., ligand density and ligand properties, can affect the success of the nano-based delivery system.
Deposition of Inhaled Levofloxacin in Cystic Fibrosis Lungs Assessed by Functional Respiratory Imaging
Authors: Schwarz Carsten , Procaccianti Claudio , Mignot Benjamin , Sadafi Hosein , Schwenck Nicolas , Murgia Xabier , Bianco Federico
Published: December 2021

Pulmonary infections caused by Pseudomonas aeruginosa (PA) represent the leading cause of pulmonary morbidity in adults with cystic fibrosis (CF). In addition to tobramycin, colistin, and aztreonam, levofloxacin has been approved in Europe to treat PA infections. Nevertheless, no lung deposition data on inhaled levofloxacin are yet available. We conducted a Functional Respiratory Imaging (FRI) study to predict the lung deposition of levofloxacin in the lungs of patients with CF. Three-dimensional airway models were digitally reconstructed from twenty high-resolution computed tomography scans obtained from historical patients’ records. Levofloxacin aerosols generated with the corresponding approved nebuliser were characterised according to pharmacopeia. The obtained data were used to inform a computational fluid dynamics simulation of levofloxacin lung deposition using breathing patterns averaged from actual CF patients’ spirometry data. Levofloxacin deposition in the lung periphery was significantly reduced by breathing patterns with low inspiratory times and high inspiratory flow rates. The intrathoracic levofloxacin deposition percentages for moderate and mild CF lungs were, respectively, 37.0% ± 13.6 and 39.5% ± 12.9 of the nominal dose. A significant albeit modest correlation was found between the central-to-peripheral deposition (C/P) ratio of levofloxacin and FEV1. FRI analysis also detected structural differences between mild and moderate CF airways. FRI revealed a significant intrathoracic deposition of levofloxacin aerosols, which distributed preferentially to the lower lung lobes, with an influence of the deterioration of FEV1 on the C/P ratio. The three-dimensional rendering of CF airways also detected structural differences between the airways of patients with mild and moderate CF.
Potentially Inappropriate Medication Prescribing Detected by Computer Algorithm among Older Patients: Results from the MAPT Study
Authors: Pagès Arnaud , Rouch Laure , Costa Nadège , Cestac Philippe , De Souto Barreto Philipe , Rolland Yves , Vellas Bruno , Molinier Laurent , Juillard-Condat Blandine ,   MAPT/DSA Group
Published: December 2021

(1) Background: Some medications may be dangerous for older patients. Potentially inappropriate medication prescribing (PIP) among older patients represents a significant cause of morbidity. The aim of this study was to create an algorithm to detect PIP in a geriatric database (Multidomain Alzheimer Preventive Trial (MAPT) study), and then to assess the algorithm construct validity by comparing the prevalence of PIP and associated factors with literature data. (2) Methods: An algorithm was constructed to detect PIP and was based on different explicit criteria among which the European list of potentially inappropriate medications (EU(7)-PIM), the STOPP and START version 2 tools. For construct validity assessment, logistic mixed-effects model repeated measures analyses were used to identify factors associated with PIP. (3) Results: Prevalence of PIP was 59.0% with the EU(7)-PIM list criteria, 43.2% with the STOPP criteria and 51.3% with the START criteria. Age, polypharmacy, and higher Charlson comorbidity index were associated with PIP. (4) Conclusions: Prevalence of PIP and associated factors are consistent with literature data, supporting the construct validity of our algorithm. This algorithm opens up interesting perspectives both in terms of analysis of very large databases and integration into e-prescribing or pharmaceutical validation software.
The Impact of a Pharmacist-Driven Staphylococcus aureus Bacteremia Initiative in a Community Hospital: A Retrospective Cohort Analysis
Authors: Berger Nate , Wright Michael , Pouliot Jonathon , Green Montgomery , Armstrong Deborah
Published: December 2021

Purpose: Staphylococcus aureus is a leading cause of bacteremia with a 30-day mortality of 20%. This study evaluated outcomes after implementation of a pharmacist-driven Staphylococcus aureus bacteremia (SAB) initiative in a community hospital. Methods: This retrospective cohort analysis compared patients admitted with SAB between May 2015 and April 2018 (intervention group) to those admitted between May 2012 and April 2015 (historical control group). Pharmacists were notified of and responded to blood cultures positive for Staphylococcus aureus by contacting provider(s) with a bundle of recommendations. Components of the SAB bundle included prompt source control, selection of appropriate intravenous antibiotics, appropriate duration of therapy, repeat blood cultures, echocardiography, and infectious diseases consult. Demographics (age, gender, and race) were collected at baseline. Primary outcome was in-hospital mortality. Compliance with bundle components was also assessed. Results: Eighty-three patients in the control group and 110 patients in the intervention group were included in this study. Demographics were similar at baseline. In-hospital mortality was lower in the intervention group (3.6% vs. 15.7%; p = 0.0033). Bundle compliance was greater in the intervention group (69.1% vs. 39.8%; p < 0.0001). Conclusions: We observed a significant reduction in in-hospital mortality and increased treatment bundle compliance in the intervention cohort with implementation of a pharmacist-driven SAB initiative. Pharmacists’ participation in the care of SAB patients in the form of recommending adherence to treatment bundle components drastically improved clinical outcomes. Widespread adoption and implementation of similar practice models at other institutions may reduce in-hospital mortality for this relatively common and life-threatening infection.
The Ecological Literacies of St. Hildegard of Bingen
Authors: Marder Michael
Published: December 2021

Literacy is, literally, a question not of education but of the letter. More than that, it is the question of the letter in the two senses the word has in English: as a symbol of the alphabet and a piece of correspondence. It is my hypothesis that ecological literacies may learn a great deal from the literalization, or even the hyper-literalization, of the letter and that they may do so by turning to the corpus of twelfth-century Benedictine abbess, polymath, and mystic St. Hildegard of Bingen. After all, Hildegard, who was exquisitely attuned to the vegetal world, which was at the core of her theological and scientific endeavors, corresponded through letters with the leading personalities of her times and also invented a language, called lingua ignota (the unknown language) replete with ignotas litteras (the unknown letters). Who better than her can spell out the senses of ecological literacy?
A Full-Aperture Image Synthesis Method for the Rotating Rectangular Aperture System Using Fourier Spectrum Restoration
Authors: Lv Guomian , Xu Hao , Feng Huajun , Xu Zhihai , Zhou Hao , Li Qi , Chen Yueting
Published: December 2021

The novel rotating rectangular aperture (RRA) system provides a good solution for space-based, large-aperture, high-resolution imaging tasks. Its imaging quality depends largely on the image synthesis algorithm, and the mainstream multi-frame deblurring approach is sophisticated and time-consuming. In this paper, we propose a novel full-aperture image synthesis algorithm for the RRA system, based on Fourier spectrum restoration. First, a numerical simulation model is established to analyze the RRA system’s characteristics and obtain the point spread functions (PSFs) rapidly. Then, each image is used iteratively to calculate the increment size and update the final restored Fourier spectrum. Both the simulation’s results and the practical experiment’s results show that our algorithm performs well in terms of objective evaluation and time consumption.
Real-Time Strain and Elasticity Imaging in Phase-Sensitive Optical Coherence Elastography Using a Computationally Efficient Realization of the Vector Method
Authors: Zaitsev Vladimir Y. , Ksenofontov Sergey Y. , Sovetsky Alexander A. , Matveyev Alexander L. , Matveev Lev A. , Zykov Alexey A. , Gelikonov Grigory V.
Published: December 2021

We present a real-time realization of OCT-based elastographic mapping local strains and distribution of the Young’s modulus in biological tissues, which is in high demand for biomedical usage. The described variant exploits the principle of Compression Optical Coherence Elastography (C-OCE) and uses processing of phase-sensitive OCT signals. The strain is estimated by finding local axial gradients of interframe phase variations. Instead of the popular least-squares method for finding these gradients, we use the vector approach, one of its advantages being increased computational efficiency. Here, we present a modified, especially fast variant of this approach. In contrast to conventional correlation-based methods and previously used phase-resolved methods, the described method does not use any search operations or local calculations over a sliding window. Rather, it obtains local strain maps (and then elasticity maps) using several transformations represented as matrix operations applied to entire complex-valued OCT scans. We first elucidate the difference of the proposed method from the previously used correlational and phase-resolved methods and then describe the proposed method realization in a medical OCT device, in which for real-time processing, a “typical” central processor (e.g., Intel Core i7-8850H) is sufficient. Representative examples of on-flight obtained elastographic images are given. These results open prospects for broad use of affordable OCT devices for high-resolution elastographic vitalization in numerous biomedical applications, including the use in clinic.
Numerical Investigation and Design of Electrically-Pumped Self-Pulsing Fano Laser Based on III-V/Silicon Integration
Authors: Zhao Yingming , Li Yu , Huang Weiping
Published: December 2021

A self-pulsing III-V/silicon laser is designed based on the Fano resonance between a bus-waveguide and a micro-ring resonator, partially covered by the graphene as a nonlinear saturable absorption component. The Fano reflector etched on the straight waveguide is used as one of the cavity mirrors in the coupling region to work with the graphene induced loss and nonlinearity to achieve pulsed lasing in GHz repetition frequency. The detailed lasing characteristics are studied numerically by using the rate equation and finite-difference time-domain (FDTD) simulations. The results show that the CMOS compatible hybrid laser can generate picosecond pulses with repetition rate at 1~3.12 GHz, which increases linearly with the injection current.
Monthly Variation and Ultraviolet Stability of Mycosporine-like Amino Acids from Red Alga Dulse Palmaria palmata in Japan
Authors: Nishida Yuki , Miyabe Yoshikatsu , Kishimura Hideki , Kumagai Yuya
Published: December 2021

Mycosporine-like amino acids (MAAs) are the natural ultraviolet (UV)-absorbing compounds from micro- and macro-algae. The MAAs in algae change with the environmental conditions and seasons. We previously determined an efficient extraction method of MAAs from red alga dulse in Usujiri (Hokkaido, Japan) and revealed monthly variation of MAA in 2019. Dulse samples in 2019 for MAA preparation were suitable from late February to April. In this study, to confirm the suitable timings to extract MAAs from Usujiri dulse, we also investigated the monthly (from January to May) variation of MAA content in 2020. There were the most MAAs in the sample on 18 March (6.696 µmol g−1 dry weight) among the samples from January to May 2020. From two years of investigation, we deduce that samples of Usujiri dulse from late February to early April were suitable for MAA preparation. The UV stability of the two major purified MAAs in Usujiri dulse—palythine and porphyra-334—was tested. The two MAAs and 2-hydroxy-4-methoxybenzophenone were stable for up to 12 h under a 312 nm lamp at 200 µW cm−2, but 2-ethylhexyl-4-methoxycinnamate formed a cis/trans-mixture in a short time. The data in this study show the suitable sampling period for Usujiri dulse and the possible application for UV protection from food and cosmetics.
Stellar Structure in a Newtonian Theory with Variable G
Authors: Fabris Júlio C. , Ottoni Túlio , Toniato Júnior D. , Velten Hermano
Published: December 2021

A Newtonian-like theory inspired by the Brans–Dicke gravitational Lagrangian has been recently proposed by us. For static configurations, the gravitational coupling acquires an intrinsic spatial dependence within the matter distribution. Therefore, the interior of astrophysical configurations may provide a testable environment for this approach as long as no screening mechanism is evoked. In this work, we focus on the stellar hydrostatic equilibrium structure in such a varying Newtonian gravitational coupling G scenario. A modified Lane–Emden equation is presented and its solutions for various values of the polytropic index are discussed. The role played by the theory parameter ω, the analogue of the Brans–Dicke parameter, in the physical properties of stars is discussed.
Characterization of a Chickpea Mutant Resistant to Phelipanche aegyptiaca Pers. and Orobanche crenata Forsk
Authors: Galili Shmuel , Hershenhorn Joseph , Smirnov Evgeny , Yoneyama Koichi , Xie Xiaonan , Amir-Segev Orit , Bellalou Aharon , Dor Evgenia
Published: December 2021

Chickpea (Cicer arietinum L.) is a major pulse crop in Israel grown on about 3000 ha spread, from the Upper Galilee in the north to the North-Negev desert in the south. In the last few years, there has been a gradual increase in broomrape infestation in chickpea fields in all regions of Israel. Resistant chickpea cultivars would be simple and effective solution to control broomrape. Thus, to develop resistant cultivars we screened an ethyl methanesulfonate (EMS) mutant population of F01 variety (Kabuli type) for broomrape resistance. One of the mutant lines (CCD7M14) was found to be highly resistant to both Phelipanche aegyptiaca and Orobanche crenata. The resistance mechanism is based on the inability of the mutant to produce strigolactones (SLs)—stimulants of broomrape seed germination. LC/MS/MS analysis revealed the SLs orobanchol, orobanchyl acetate, and didehydroorobanchol in root exudates of the wild type, but no SLs could be detected in the root exudates of CCD7M14. Sequence analyses revealed a point mutation (G-to-A transition at nucleotide position 210) in the Carotenoid Cleavage Dioxygenase 7 (CCD7) gene that is responsible for the production of key enzymes in the biosynthesis of SLs. This nonsense mutation resulted in a CCD7 stop codon at position 70 of the protein. The influences of the CCD7M14 mutation on chickpea phenotype and chlorophyll, carotenoid, and anthocyanin content were characterized.
Understanding Land Changes for Sustainable Environmental Management: The Case of Basilicata Region (Southern Italy)
Authors: Cillis Giuseppe , Tucci Biagio , Santarsiero Valentina , Nolè Gabriele , Lanorte Antonio
Published: December 2021

Sustainable land management is one of the key actions for the achievement of objectives set by the 2030 Agenda for Sustainable Development. In particular, land represents a fundamental resource to address issues of climate change, biodiversity preservation, maintaining ecosystem services, and at the same time ensuring shared prosperity and well-being. Therefore, it is necessary to activate strategies to monitor changes in land use and land cover in order to evaluate strategies for proper management. To do this, the new open source geospatial analysis tools and the increasing availability of remote sensed open data can allow the activation of methodologies for monitoring changes in land use and land cover in order to provide data usable in other research areas or, for example, to implement a decision support system for environmental sustainability. In this study, a GIS approach based on open remote sensing data has been used to perform a spatial analysis of land cover changes within the Basilicata region (Southern Italy) that is spatially expeditious yet accurate. The results showed a very evident land transformation with important repercussions on the environmental components. The ease of use of techniques makes this methodology replicable in other territory and can be used as a preliminary approach to sustainable development model.
Synthesis, Characterization and Evaluation of Supercapacitive Response of Dodecylbenzenesulphonic Acid (DBSA) Doped Polypyrrole/Zirconium Dioxide Composites
Authors: Ullah Rizwan , Khan Mehtab , Khattak Rozina , Khan Nadia , Khan Muhammad Sufaid , El-Badry Yaser A.
Published: December 2021

An in-situ chemical oxidative method was used to effectively synthesize a promising supercapacitor material based on PPy/ZrO2 composites. The synthesized materials were characterized by different analytical techniques, such as UV/visible (UV/Vis) spectroscopy, Fourier-transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The inclusion of ZrO2 into the PPy matrix was verified by vibrational spectra and structural analyses. The (TGA) results showed that incorporating ZrO2 into the polymeric matrix improved its thermal stability. In addition, the electrochemical properties of the synthesizedmaterials were investigated byusing cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The PPy/ZrO2 composite demonstrated excellent super capacitive performance, and high specific capacity of 337.83 F/g, with an exceedingly high energy density of 187.68 Wh/kg at a power density of 1000 W/kg. The composite materials maintain good stability after 1000 charge and discharge cycles, with 85% capacitance retention. The PPy/ZrO2 possesses a high capacitance, an attractive micro-morphology, and a simple synthesis method. The findings indicate that the PPy/ZrO2 composite could be a promising electrode material for high-performance supercapacitor applications.
A Degradable Inverse Vulcanized Copolymer as a Coating Material for Urea Produced under Optimized Conditions
Authors: Ghumman Ali Shaan Manzoor , Shamsuddin Rashid , Nasef Mohamed Mahmoud , Krivoborodov Efrem G. , Ahmad Sohaira , Zanin Alexey A. , Mezhuev Yaroslav O. , Abbasi Amin
Published: December 2021

Global enhancement of crop yield is achieved using chemical fertilizers; however, agro-economy is affected due to poor nutrient uptake efficacy (NUE), which also causes environmental pollution. Encapsulating urea granules with hydrophobic material can be one solution. Additionally, the inverse vulcanized copolymer obtained from vegetable oils are a new class of green sulfur-enriched polymer with good biodegradation and better sulfur oxidation potential, but they possess unreacted sulfur, which leads to void generations. In this study, inverse vulcanization reaction conditions to minimize the amount of unreacted sulfur through response surface methodology (RSM) is optimized. The copolymer obtained was then characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR confirmed the formation of the copolymer, TGA demonstrated that copolymer is thermally stable up to 200 °C temperature, and DSC revealed the sulfur conversion of 82.2% (predicted conversion of 82.37%), which shows the goodness of the model developed to predict the sulfur conversion. To further maximize the sulfur conversion, 5 wt% diisopropenyl benzene (DIB) as a crosslinker is added during synthesis to produce terpolymer. The urea granule is then coated using terpolymer, and the nutrient release longevity of the coated urea is tested in distilled water, which revealed that only 65% of its total nutrient is released after 40 days of incubation. The soil burial of the terpolymer demonstrated its biodegradability, as 26% weight loss happens in 52 days of incubation. Thus, inverse vulcanized terpolymer as a coating material for urea demonstrated far better nutrient release longevity compared with other biopolymers with improved biodegradation; moreover, these copolymers also have potential to improve sulfur oxidation.
Carboxymethyl Cellulose Hydrogel from Biomass Waste of Oil Palm Empty Fruit Bunch Using Calcium Chloride as Crosslinking Agent
Authors: Tuan Mohamood Nur Fattima’ Al-Zahara’ , Abdul Halim Abdul Hakam , Zainuddin Norhazlin
Published: December 2021

Carboxymethyl cellulose (CMC) is modified cellulose extracted from oil palm empty fruit bunch (OPEFB) biomass waste that has been prepared through etherification using sodium monochloroacetate (SMCA) in the presence of sodium hydroxide. In this research, CMC hydrogel was prepared using calcium chloride (CaCl2) as the chemical crosslinker. Throughout the optimization process, four important parameters were studied, which were: (1) CMC concentration, (2) CaCl2 concentration, (3) reaction time, and (4) reaction temperature. From the results, the best gel content obtained was 28.11% at 20% (w/v) of CMC with 1% (w/v) of CaCl2 in 24 h reaction at room temperature. Meanwhile, the degree of swelling for CMC hydrogel was 47.34 g/g. All samples were characterized using FT-IR, XRD, TGA, and FESEM to study and compare modification on the OPEFB cellulose. The FT-IR spectrum of CMC hydrogel showed a shift of COO− peaks at 1585 cm−1 and 1413 cm−1, indicating the substitution of Ca2+ into the CMC molecular chains. The XRD diffractogram of CMC hydrogel showed no observation of sharp peaks, which signified an amorphous hydrogel phase. The CrI value also proved the decrement of the crystalline nature of CMC hydrogel. TGA–DTG thermograms showed that the Tmax of CMC hydrogel at 293.33 °C is slightly better in thermal stability compared to CMC. Meanwhile, the FESEM micrograph of CMC hydrogel showed interconnected pores indicating the crosslinkages in CMC hydrogel. CMC hydrogel was successfully synthesized using CaCl2 as a crosslinking agent, and its swelling ability can be used in various applications such as drug delivery systems, industrial effluent, food additives, heavy metal removal, and many more.
Physical, Mechanical, and Water Vapor Barrier Properties of Starch/Cellulose Nanofiber/Thymol Bionanocomposite Films
Authors: Othman Siti Hajar , Wane Bilguisse Mamadou , Nordin Norhazirah , Noor Hasnan Noor Zafira , A. Talib Rosnita , Karyadi Joko Nugroho Wahyu
Published: December 2021

The application of starch films, such as food packaging materials, has been restricted due to poor mechanical and barrier properties. However, the addition of a reinforcing agent, cellulose nanofibers (CNF) and also thymol, into the films, may improve the properties of films. This work investigates the effects of incorporating different concentrations of thymol (3, 5, 7, and 10 wt.%) on physical, mechanical, water vapor barrier, and antibacterial properties of corn starch films, containing 1.5 wt.% CNF produced using the solvent casting method. The addition of thymol does not significantly affect the color and opacity of the films. It is found that the tensile strength and Young’s modulus of the films decreases from 10.6 to 6.3 MPa and from 436.9 to 209.8 MPa, respectively, and the elongation at break increased from 110.6% to 123.5% with the incorporation of 10 wt.% thymol into the films. Furthermore, the addition of thymol at higher concentrations (7 and 10 wt.%) improved the water vapor barrier of the films by approximately 60.0%, from 4.98 × 10—9 to 2.01 × 10—9 g/d.m.Pa. Starch/CNF/thymol bionanocomposite films are also found to exhibit antibacterial activity against Escherichia coli. In conclusion, the produced starch/CNF/thymol bionanocomposite films have the potential to be used as antibacterial food packaging materials.
Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6
Authors: Robalino David Herrera , Durán del Amor María del Mar , Almagro Gómez Carmen María , Hernández Cifre José Ginés
Published: December 2021

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.
Towards the Development of a Strategy to Characterize and Model the Rheological Behavior of Filled, Uncured Rubber Compounds
Authors: Spanjaards M. M. A. , Peters G. W. M. , Hulsen M. A. , Anderson P. D.
Published: December 2021

In this paper, an experimental strategy is presented to characterize the rheological behavior of filled, uncured rubber compounds. Oscillatory shear experiments on a regular plate-plate rheometer are combined with a phenomenological thixotropy model to obtain model parameters that can be used to describe the steady shear behavior. We compare rate- and stress-controlled kinetic equations for a structure parameter that determines the deformation history-dependent spectrum and, thus, the dynamic thixotropic behavior of the material. We keep the models as simple as possible and the characterization straightforward to maximize applicability. The model can be implemented in a finite element framework as a tool to simulate realistic rubber processing. This will be the topic of another work, currently under preparation. In shaping processes, such as rubber- and polymer extrusion, with realistic processing conditions, the range of shear rates is far outside the range obtained during rheological characterization. Based on some motivated choices, we will present an approach to extend this range.
Multi-Objective Optimisation of Curing Cycle of Thick Aramid Fibre/Epoxy Composite Laminates
Authors: Zhang Guowei , Luo Ling , Lin Ting , Zhang Boming , Wang He , Qu Yuao , Meng Bangke
Published: December 2021

Aramid fibre-reinforced epoxy composites (AF/EP) are promising materials in the aerospace, transportation, and civil fields owing to their high strength, high modulus, and light weight. Thick composite laminates are gradually being applied to large composite structures such as wind turbine blades. During curing, temperature overheating is a common problem in thick composites, which leads to matrix degradation, thermal residual stresses, and uneven curing. This paper proposes a signal-to-noise ratio (SNR) method to optimise the curing cycle of thick AF/EP laminates and reduce the overheating temperature. During curing, the temperature and strain evolution in a thick AF/EP laminate were monitored using fibre Bragg grating sensors. The effects of the curing factors on the overheating temperature of the thick AF/EP laminate were evaluated using the Taguchi method and predicted via the SNR method and analysis of variance. The results indicate that the dwelling temperature is the main factor affecting the overheating temperature. The optimal curing cycle involves an overheating temperature of 192.72 °C, which constitutes an error of 2.58% compared to the SNR method predictions. Additionally, in comparison to the initial curing cycle, the overshoot temperature in the optimised curing cycle was reduced by 58.48 °C, representing a reduction ratio of 23.28%.
Copolymer Involving 2-Hydroxyethyl Methacrylate and 2-Chloroquinyl Methacrylate: Synthesis, Characterization and In Vitro 2-Hydroxychloroquine Delivery Application
Authors: Aljubailah Abeer , Alharbi Wafa Nazzal Odis , Haidyrah Ahmed S. , Al-Garni Tahani Saad , Saeed Waseem Sharaf , Semlali Abdelhabib , Alqahtani Saad M. S. , Al-Owais Ahmad Abdulaziz , Karami Abdulnasser Mahmoud , Aouak Taieb
Published: December 2021

The Poly(2-chloroquinyl methacrylate-co-2-hydroxyethyl methacrylate) (CQMA-co-HEMA) drug carrier system was prepared with different compositions through a free-radical copolymerization route involving 2-chloroquinyl methacrylate (CQMA) and 2-hydroxyethyl methacrylate) (HEMA) using azobisisobutyronitrile as the initiator. 2-Chloroquinyl methacrylate monomer (CQMA) was synthesized from 2-hydroxychloroquine (HCQ) and methacryloyl chloride by an esterification reaction using triethylenetetramine as the catalyst. The structure of the CQMA and CQMA-co-HEMA copolymers was confirmed by a CHN elementary analysis, Fourier transform infra-red (FTIR) and nuclear magnetic resonance (NMR) analysis. The absence of residual aggregates of HCQ or HCQMA particles in the copolymers prepared was confirmed by a differential scanning calorimeter (DSC) and XR-diffraction (XRD) analyses. The gingival epithelial cancer cell line (Ca9-22) toxicity examined by a lactate dehydrogenase (LDH) assay revealed that the grafting of HCQ onto PHEMA slightly affected (4.2–9.5%) the viability of the polymer carrier. The cell adhesion and growth on the CQMA-co-HEMA drug carrier specimens carried out by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay revealed the best performance with the specimen containing 3.96 wt% HCQ. The diffusion of HCQ through the polymer matrix obeyed the Fickian model. The solubility of HCQ in different media was improved, in which more than 5.22 times of the solubility of HCQ powder in water was obtained. According to Belzer, the in vitro HCQ dynamic release revealed the best performance with the drug carrier system containing 4.70 wt% CQMA.
Physical and Mechanical Characterization of Titica Vine (Heteropsis flexuosa) Incorporated Epoxy Matrix Composites
Authors: da Cunha Juliana , Nascimento Lucio , da Luz Fernanda , Monteiro Sergio , Lemos Maurício , da Silva Cristina , Simonassi Noan
Published: December 2021

Titica vine (Heteropsis flexuosa) is a typical plant of the Amazon region commonly used for making baskets, bags, brooms and furniture, owing to its stiff fibers. In spite of its interesting properties, there is so far no reported information regarding the use of titica vine fibers (TVFs) in engineering composite materials. In this work, the TVF and its epoxy composites were for the first time physically, thermally and mechanically characterized. Additionally, the effect of two kinds of chemical treatments, one with sodium carbonate and one with calcium lignosulfonate, as well as different volume fractions, 10, 20, 30 and 40 vol%, of TVF-reinforced composites were assessed for corresponding basic properties. The thermogravimetric results of the composites reveal enhanced thermal stability for higher TVF content. In addition, the composite incorporated with 40 vol% of TVFs treated with sodium carbonate absorbed 19% more water than the composites with untreated fibers. By contrast, the calcium lignosulfonate treatment decreased water absorption by 8%. The Charpy and Izod impact tests showed that the composites, incorporated with the highest investigated volume fraction (40 vol%) of TVF, significantly increased the absorbed energy by 18% and 28%, respectively, compared to neat epoxy. ANOVA and Tukey statistical analyses displayed no direct influence of the chemical treatments on the energy absorption of the composites for either impact tests. SEM images revealed the main fracture mechanisms responsible for the performance of TVF composites.
Mechanical and Dynamic Mechanical Properties of the Amino Silicone Oil Emulsion Modified Ramie Fiber Reinforced Composites
Authors: He Liping , Xia Fan , Wang Yuan , Yuan Jianmin , Chen Dachuan , Zheng Junchao
Published: December 2021

The mechanical and dynamic mechanical properties, interface adhesion and microstructures of the amino silicone oil emulsion (ASO) modified short ramie fiber reinforced polypropylene composites (RFPCs) with different fiber fractions were investigated. The RFPCs were made through a combined process of extrusion and injection molding. Mechanical property tests of the RFPCs revealed enhancements in tensile and flexural strengths with increase of the fiber fraction due to the high stiffness of the fiber filler and a better interfacial bonding from ASO treatment. The dynamic mechanical analysis (DMA) results indicated that fiber incorporation plays an important role in DMA parameters (storage modulus, loss modulus, and damping ratio) at Tg by forming an improved interfacial adhesion and providing more effective stress transfer rate and energy dissipation between matrix and fiber. The phase behavior analysis suggests all the RFPCs are a kind of heterogeneity system based on the Cole-Cole plot analysis.
Investigation of Dye Dopant Influence on Electrooptical and Morphology Properties of Polymeric Acceptor Matrix Dedicated for Ternary Organic Solar Cells
Authors: Lewińska Gabriela , Jeleń Piotr , Kanak Jarosław , Walczak Łukasz , Socha Robert , Sitarz Maciej , Sanetra Jerzy , Marszałek Konstanty Waldemar
Published: December 2021

The publication presents the results of investigations of the influence of dye dopant on the electrooptical and morphology properties of a polymeric donor:acceptor mixture. Ternary thin films (polymer:dye:fullerene) were investigated for potential application as an active layer in organic solar cells. The aim of the research is to determine the effect of selected dye materials (dye D131, dye D149, dye D205, dye D358) on the three-component layer and their potential usefulness as an additional donor in ternary cells, based on P3HT donor and PC71BM acceptor. UV–vis spectroscopy studies were performed, and absorption and luminescence spectra were determined. Ellipsometry parameters for single dye and ternary layers have been measured. The analyses were performed using the Raman spectroscopy method, and the Raman spectra of the mixtures and single components have been determined. Organic layers were prepared and studied using scanning electron microscope and atomic force microscope. For dyes, ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy studies were carried out and the ternary system was presented and analyzed in terms of energy bands.
Transparent Self-Cleaning Coatings Based on Colorless Polyimide/Silica Sol Nanocomposite
Authors: Choi Yun-Je , Ko Ju-Hee , Jin Seung-Won , An Hyun-Soo , Kim Dam-Bi , Yoon Kang-Hoon , Kim Hyun-Woo , Chung Chan-Moon
Published: December 2021

We herein report transparent self-cleaning coatings based on polyimide-fluorinated silica sol (PIFSS) nanocomposite. Polyamic acid-silica sol (PASS) suspensions were synthesized by adding four different amounts of a silica sol suspension to each end-capped polyamic acid solution. The PASS suspensions were spin-coated on glass slides, thermally imidized and treated with triethoxy-1H,1H,2H,2H-perfluorodecylsilane (TEFDS) to prepare PIFSS coatings. The PIFSS coatings showed high resistance to separation from glass substrates and thermal stability. Furthermore, the PIFSS coatings on the glass substrate could be cleanly removed using polar aprotic solvents and repeated coating was possible. As the amount of silica sol particles in the PIFSS coating was increased, the hydrophobic contact angle increased. Among them, PIFSS-10 and PIFSS-15 coatings showed nearly superhydrophobic contact angles (144° and 148°, respectively) and good self-cleaning property. It was confirmed by SEM and AFM studies that their hydrophobic and self-cleaning properties are due to uniform particle distribution and relatively high surface roughness. PIFSS-10 coating showed a high transmittance value (88%) at 550 nm and good self-cleaning property, therefore suitable as a transparent self-cleaning coating. The advantages of the coating are that the fabrication process is simple, and the substrate is reusable. The PIFSS coating is expected to be applied in solar cell panels, windows, lenses and safety goggles.
Prolonged Thermal Relaxation of the Thermosetting Polymers
Authors: Korolev Alexander , Mishnev Maxim , Vatin Nikolai Ivanovich , Ignatova Anastasia
Published: December 2021

The rigidity of structures made of polymer composite materials, operated at elevated temperatures, is mainly determined by the residual rigidity of the polymer binder (which is very sensitive to elevated temperatures); therefore, the study of ways to increase the rigidity of polymer materials under heating (including prolonged heating) is relevant. In the previous research, cured thermosetting polymer structure’s non-stability, especially under heating, is determined by its supra-molecular structure domain’s conglomerate character and the high entropy of such structures. The polymer elasticity modeling proved the significance of the entropy factor and layer (EPL) model application. The prolonged heating makes it possible to release adsorptive inter-layer bonds and volatile groups. As a result, the polymer structure is changing, and inner stress relaxation occurs due to this thermo-process, called thermo-relaxation. The present study suggests researching thermo-relaxation’s influence on polymers’ deformability under load and heating. The research results prove the significant polymer structure modification due to thermo-relaxation, with the polymer entropy parameter decreasing, the glassing onset temperature point (Tg) increasing by 1.3–1.7 times, and the modulus of elasticity under heating increasing by 1.5–2 times.
Flammability and Thermal Kinetic Analysis of UiO-66-Based PMMA Polymer Composites
Authors: Shen Ruiqing , Yan Tian-Hao , Ma Rong , Joseph Elizabeth , Quan Yufeng , Zhou Hong-Cai , Wang Qingsheng
Published: December 2021

Metal–organic frameworks (MOFs) are emerging as novel flame retardants for polymers, which, typically, can improve their thermal stability and flame retardancy. However, there is a lack of specific studies on the thermal decomposition kinetics of MOF-based polymer composites, although it is known that they are important for the modeling of flaming ignition, burning, and flame spread over them. The thermal decomposition mechanisms of poly (methyl methacrylate) (PMMA) have been well investigated, which makes PMMA an ideal polymer to evaluate how fillers affect its decomposition process and kinetics. Thus, in this study, UiO-66, a common type of MOF, was embedded into PMMA to form a composite. Based on the results from the microscale combustion calorimeter, the values of the apparent activation energy of PMMA/UiO-66 composites were calculated and compared against those of neat PMMA. Furthermore, under cone calorimeter tests, UiO-66, at only 1.5 wt%, can reduce the maximum burning intensity and average mass loss rate of PMMA by 14.3% and 12.4%, respectively. By combining UiO-66 and SiO2 to form a composite, it can contribute to forming a more compact protective layer, which shows a synergistic effect on reducing the maximum burning intensity and average mass loss rate of PMMA by 22.0% and 14.7%, respectively.
Effect of PMMA Molecular Weight on Its Localization during Crystallization of PVDF in Their Blends
Authors: Lin Taotao , Li Yongjin , Wang Jiayao , You Jichun
Published: December 2021

In miscible crystalline/amorphous polymer blends, the exclusion behaviors of the latter with various molecular weights during the crystallization of the former were investigated by the combination of SAXS and DSC by taking a PVDF/PMMA blend as an example. The ratio between internal crystallinity from SAXS and overall crystallinity of the entire blend from DSC was employed to characterize the exclusion of PMMA. Our results indicate that the molecular weight of the amorphous component produces a remarkable influence on the diffusion coefficient (D) and the crystal growth rate (G) of the crystalline component. There are both inter-lamellar and inter-fibrillar structures when PVDF blended with lower-molecular-weight PMMA. With increasing molecular weight of PMMA, the decrease in crystal growth rate (G) dominates the enhanced exclusion behaviors of PMMA, resulting in bigger pores after extraction. Our results are significant not only for the basic understanding of crystallization in polymer blends, but also for the fabrication and structure control of porous structures based on crystallization templates.
Characterizations and Significantly Enhanced Dielectric Properties of PVDF Polymer Nanocomposites by Incorporating Gold Nanoparticles Deposited on BaTiO3 Nanoparticles
Authors: Sreejivungsa Kaniknun , Phromviyo Nutthakritta , Swatsitang Ekaphan , Thongbai Prasit
Published: December 2021

Poly(vinylidene fluoride) (PVDF) nanocomposites were fabricated by incorporating BaTiO3 nanoparticles (particle size of ~100 nm, nBT), which were deposited by Au nanoparticles (nAu) with an average particle size of 17.8 ± 4.0 nm using a modified Turkevich method. Systematic characterizations on the synthesized nAu-nBT hybrid nanoparticles and nAu-nBT/PVDF nanocomposites with different contents of a filler were performed. The formation of nAu-nBT hybrid nanoparticles was confirmed with the calculated nAu:nBT ratio of 0.5:99.5 wt.%. The homogeneous dispersion of nAu and nBT in the PVDF polymer was obtained due to the interaction between the negative surface charge of the nAu-nBT filler (compared to that of the nBT) and polar β-PVDF phase, which was confirmed by the zeta potential measurement and Fourier-transform infrared spectroscopy, respectively. A significantly increased dielectric permittivity (ε′ ~ 120 at 103 Hz) with a slight temperature-dependent of <±15% ranging from −20 to 140 °C was obtained. Notably, a low loss tangent (tanδ < 0.08) was obtained even at a high temperature of 140 °C. Therefore, incorporating a PVDF polymer with nAu-nBT hybrid nanoparticles is an attractive method to improve the dielectric properties of a PVDF polymer for dielectrics applications.
Kinetic Assessment of Mechanical Properties of a Cellulose Board Aged in Mineral Oil and Synthetic Ester
Authors: Fernández-Diego Cristina , Ortiz Alfredo , Carrascal Isidro A. , Fernández Inmaculada , Renedo Carlos J.
Published: December 2021

In oil-immersed power transformers, the insulation system is constituted of a dielectric oil–solid combination. The insulation oil generally used is mineral oil; however, this fluid has started to be substituted by natural and synthetic esters due to their higher biodegradability and flash point. The introduction of a new fluid in the insulation system of power transformers requires kinetic models that can estimate the degradation rate of insulation solids. The aim of this work was to go further in quantifying through different kinetic models the deterioration suffered by a commercial cellulose board (PSP 3055), which is one of the solid materials used in the insulation system of oil-filled transformers. The aging study was extended to cellulose board specimens immersed in two different oils (mineral and synthetic ester). It was obtained that there is a lower degradation when synthetic ester is used in the insulation system. Additionally, it can be concluded that the use of mechanical properties to quantify the degradation of the cellulose board through kinetic models provides information about the different behavior shown by PSP 3055 when different fiber direction angles are considered.