bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Dynamics Simulation on Mechanical and Piezoelectric Properties of Boron Nitride Honeycomb Structures
Authors: Xie Lu , Wang Tianhua , He Chenwei , Sun Zhihui , Peng Qing
Published: July 2019

Boron nitride honeycomb structure is a new three-dimensional material similar to carbon honeycomb, which has attracted a great deal of attention due to its special structure and properties. In this paper, the tensile mechanical properties of boron nitride honeycomb structures in the zigzag, armchair and axial directions are studied at room temperature by using molecular dynamics simulations. Effects of temperature and strain rate on mechanical properties are also discussed. According to the observed tensile mechanical properties, the piezoelectric effect in the zigzag direction was analyzed for boron nitride honeycomb structures. The obtained results showed that the failure strains of boron nitride honeycomb structures under tensile loading were up to 0.83, 0.78 and 0.55 in the armchair, zigzag and axial directions, respectively, at room temperature. These findings indicated that boron nitride honeycomb structures have excellent ductility at room temperature. Moreover, temperature had a significant effect on the mechanical and tensile mechanical properties of boron nitride honeycomb structures, which can be improved by lowering the temperature within a certain range. In addition, strain rate affected the maximum tensile strength and failure strain of boron nitride honeycomb structures. Furthermore, due to the unique polarization of boron nitride honeycomb structures, they possessed an excellent piezoelectric effect. The piezoelectric coefficient e obtained from molecular dynamics was 0.702   C / m 2 , which was lower than that of the monolayer boron nitride honeycomb structures, e = 0.79   C / m 2 . Such excellent piezoelectric properties and failure strain detected in boron nitride honeycomb structures suggest a broad prospect for the application of these new materials in novel nanodevices with ultrahigh tensile mechanical properties and ultralight-weight materials.
Carbon Nanofiber-Based Functional Nanomaterials for Sensor Applications
Authors: Wang Zhuqing , Wu Shasha , Wang Jian , Yu Along , Wei Gang
Published: July 2019

Carbon nanofibers (CNFs) exhibit great potentials in the fields of materials science, biomedicine, tissue engineering, catalysis, energy, environmental science, and analytical science due to their unique physical and chemical properties. Usually, CNFs with flat, mesoporous, and porous surfaces can be synthesized by chemical vapor deposition and electrospinning techniques with subsequent chemical treatment. Meanwhile, the surfaces of CNFs are easy to modify with various materials to extend the applications of CNF-based hybrid nanomaterials in multiple fields. In this review, we focus on the design, synthesis, and sensor applications of CNF-based functional nanomaterials. The fabrication strategies of CNF-based functional nanomaterials by adding metallic nanoparticles (NPs), metal oxide NPs, alloy, silica, polymers, and others into CNFs are introduced and discussed. In addition, the sensor applications of CNF-based nanomaterials for detecting gas, strain, pressure, small molecule, and biomacromolecules are demonstrated in detail. This work will be beneficial for the readers to understand the strategies for fabricating various CNF-based nanomaterials, and explore new applications in energy, catalysis, and environmental science.
TiO2 and PEEK Reinforced 3D Printing PMMA Composite Resin for Dental Denture Base Applications
Authors: Chen Sheng-Gui , Yang Junzhong , Jia Yong-Guang , Lu Bingheng , Ren Li
Published: July 2019

The future of manufacturing applications in three-dimensional (3D) printing depends on the improvement and the development of materials suitable for 3D printing technology. This study aims to develop an applicable and convenient protocol for light-curing resin used in 3D industry, which could enhance antibacterial and mechanical properties of polymethyl methacrylate (PMMA) resin through the combination of nano-fillers of surface modified titanium dioxide (TiO2) and micro-fillers of polyetheretherketone (PEEK). PMMA-based composite resins with various additions of TiO2 and PEEK were prepared and submitted to characterizations including mechanical properties, distribution of the fillers (TiO2 or/and PEEK) on the fractured surface, cytotoxicity, antibacterial activity, and blood compatibility assessment. These results indicated that the reinforced composite resins of PMMA (TiO2-1%-PEEK-1%) possessed the most optimized properties compared to the other groups. In addition, we found the addition of 1% of TiO2 would be an effective amount to enhance both mechanical and antibacterial properties for PMMA composite resin. Furthermore, the model printed by PMMA (TiO2-1%-PEEK-1%) composite resin showed a smooth surface and a precise resolution, indicating this functional dental restoration material would be a suitable light-curing resin in 3D industry.
Physical Activity, Cardiorespiratory Fitness, and the Metabolic Syndrome
Authors: Myers Jonathan , Kokkinos Peter , Nyelin Eric
Published: July 2019

Both observational and interventional studies suggest an important role for physical activity and higher fitness in mitigating the metabolic syndrome. Each component of the metabolic syndrome is, to a certain extent, favorably influenced by interventions that include physical activity. Given that the prevalence of the metabolic syndrome and its individual components (particularly obesity and insulin resistance) has increased significantly in recent decades, guidelines from various professional organizations have called for greater efforts to reduce the incidence of this condition and its components. While physical activity interventions that lead to improved fitness cannot be expected to normalize insulin resistance, lipid disorders, or obesity, the combined effect of increasing activity on these risk markers, an improvement in fitness, or both, has been shown to have a major impact on health outcomes related to the metabolic syndrome. Exercise therapy is a cost-effective intervention to both prevent and mitigate the impact of the metabolic syndrome, but it remains underutilized. In the current article, an overview of the effects of physical activity and higher fitness on the metabolic syndrome is provided, along with a discussion of the mechanisms underlying the benefits of being more fit or more physically active in the prevention and treatment of the metabolic syndrome.
Partially Hydrolysed Whey-Based Formulae with Reduced Protein Content Support Adequate Infant Growth and Are Well Tolerated: Results of a Randomised Controlled Trial in Healthy Term Infants
Authors: Rigo Jacques , Schoen Stefanie , Verghote Marc , van Overmeire Bart , Marion Wivinne , Abrahamse-Berkeveld Marieke , Alliet Philippe
Published: July 2019

The current study aimed to investigate growth, safety and tolerance of partially hydrolysed infant formulae in healthy full-term infants. Fully formula-fed infants were randomised ≤14 days of age to receive a partially hydrolysed whey formula with 2.27 g protein/100 kcal (pHF2.27) or the same formula with 1.8 g or 2.0 g protein/100 kcal (pHF1.8 and pHF2.0) until 4 months of age. The primary outcome was equivalence in daily weight gain within margins of ± 3 g/day; comparison with WHO Child Growth Standards; gastrointestinal tolerance parameters and number of (serious) adverse events were secondary outcomes. A total of 207 infants were randomised, and 61 (pHF1.8), 46 (pHF2.0) and 48 (pHF2.27) infants completed the study per protocol. Equivalence in daily weight gain was demonstrated for the comparison of pHF1.8 and pHF2.27, i.e., the estimated difference was −1.12 g/day (90% CI: [−2.72; 0.47]) but was inconclusive for the comparisons of pHF2.0 and pHF2.27 with a difference of −2.52 g/day (90% CI: [−4.23; −0.81]). All groups showed adequate infant growth in comparison with the World Health Organization (WHO) Child Growth Standards. To conclude, the evaluated partially hydrolysed formulae varying in protein content support adequate growth and are safe and well tolerated in healthy infants.
Fatty Acid Profile and Cardiometabolic Markers in Relation with Diet Type and Omega-3 Supplementation in Spanish Vegetarians
Authors: Salvador Ana M. , García-Maldonado Elena , Gallego-Narbón Angélica , Zapatera Belén , Vaquero M. Pilar
Published: July 2019

Plant-based diets are becoming increasingly popular, and scientific information concerning the nutritional status in this population is needed. This study determined the fatty acid profile of Spanish lacto-ovo vegetarians (LO-vegetarians) and vegans. Participants were 104 healthy adults, LO-vegetarians (n = 49) and vegans (n = 55). Lifestyle habits and consumption of food and omega-3 supplements were estimated by questionnaires. BMI, blood pressure, and abdominal and body fat were determined. Serum was collected to analyze fatty acids, glucose, lipids, homocysteine, insulin, and leptin. Volunteers were classified according to serum omega-6 to omega-3 (n-6/n-3) ratio into three groups: n-6/n-3 < 10, n-6/n-3 ≥ 10 to 20, and n-6/n-3 > 20. Results showed low cardiovascular risk and high insulin sensitivity with negligible differences between diet types. Linoleic acid (C18:2n-6) was the major serum fatty acid, followed by oleic (C18:1n-9) and palmitic (C16:0) acids. In contrast, serum eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) were (median, interquartile range) 0.27, 0.18% and 1.59, and 0.93%, respectively. Users of n-3 supplements (<10% of total vegetarians) had significantly higher EPA than non-users, while frequent consumption of flax-seeds was associated with increased α-linolenic acid (C18:3n-3). However, neither n-3 supplementation nor food consumption affected DHA levels in this vegetarian population.
Weight Loss and Hypertension in Obese Subjects
Authors: Fantin Francesco , Giani Anna , Zoico Elena , Rossi Andrea P. , Mazzali Gloria , Zamboni Mauro
Published: July 2019

Arterial hypertension is strongly related to overweight and obesity. In obese subjects, several mechanisms may lead to hypertension such as insulin and leptin resistance, perivascular adipose tissue dysfunction, renal impairment, renin-angiotensin-aldosterone-system activation and sympathetic nervous system activity. Weight loss (WL) seems to have positive effects on blood pressure (BP). The aim of this review was to explain the mechanisms linking obesity and hypertension and to evaluate the main studies assessing the effect of WL on BP. We analysed studies published in the last 10 years (13 studies either interventional or observational) showing the effect of WL on BP. Different WL strategies were taken into account—diet and lifestyle modification, pharmacological intervention and bariatric surgery. Although a positive effect of WL could be identified in each study, the main difference seems to be the magnitude and the durability of BP reduction over time. Nevertheless, further follow-up data are needed: there is still a lack of evidence about long term effects of WL on hypertension. Hence, given the significant results obtained in several recent studies, weight management should always be pursued in obese patients with hypertension.
Diet and Neurodevelopmental Score in a Sample of One-Year-Old Children—A Cross-Sectional Study
Authors: Blomkvist Eli Anne Myrvoll , Hillesund Elisabet Rudjord , Helland Sissel Heidi , Simhan Indra , Øverby Nina Cecilie
Published: July 2019

Environmental factors in the first years of life are crucial for a child’s neurodevelopment. Research on the association between breastfeeding and neurodevelopment is inconclusive, while research on the possible association between other dietary factors and neurodevelopment is inadequate in children as young as one year of age. The aim of the present study was to investigate associations between both breastfeeding and other dietary factors and the neurodevelopment of one-year-old children in Norway. Methods: Participants were recruited from kindergartens in four Norwegian counties in 2017. A questionnaire including questions about dietary factors and breastfeeding, and a standardised age-related questionnaire on neurodevelopment (the Ages and Stages Questionnaire), were completed by parents of one-year-olds. Linear regressions adjusting for relevant covariates were conducted to explore the associations. Results: In our sample of 212 one-year-old children, a longer duration of breastfeeding was associated with higher neurodevelopmental scores. Dietary intake of fish, fruits and vegetables was also strongly associated with higher neurodevelopmental scores, even after adjustment for breastfeeding and maternal education. Conclusion: Our results indicate that healthy dietary factors are important for neurodevelopment in young children, with measurable effects already at the age of one year.
Assessing the Occurrence of Waterborne Viruses in Reuse Systems: Analytical Limits and Needs
Authors: Gerba Charles P. , Betancourt Walter Q.
Published: July 2019

Detection of waterborne enteric viruses is an essential tool in assessing the risk of waterborne transmission. Cell culture is considered a gold standard for detection of these viruses. However, it is important to recognize the uncertainty and limitations of enteric virus detection in cell culture. Cell culture cannot support replication of all virus types and strains, and numerous factors control the efficacy of specific virus detection assays, including chemical additives, cell culture passage number, and sequential passage of a sample in cell culture. These factors can result in a 2- to 100-fold underestimation of virus infectivity. Molecular methods reduce the time for detection of viruses and are useful for detection of those that do not produce cytopathogenic effects. The usefulness of polymerase chain reaction (PCR) to access virus infectivity has been demonstrated for only a limited number of enteric viruses and is limited by an understanding of the mechanism of virus inactivation. All of these issues are important to consider when assessing waterborne infectious viruses and expected goals on virus reductions needed for recycled water. The use of safety factors to account for this may be useful to ensure that the risks in drinking water and recycled water for potable reuse are minimized.
Identification of Catalposide Metabolites in Human Liver and Intestinal Preparations and Characterization of the Relevant Sulfotransferase, UDP-glucuronosyltransferase, and Carboxylesterase Enzymes
Authors: Hwang Deok-Kyu , Kim Ju-Hyun , Shin Yongho , Choi Won-Gu , Kim Sunjoo , Cho Yong-Yeon , Lee Joo Young , Kang Han Chang , Lee Hye Suk
Published: July 2019

Catalposide, an active component of Veronica species such as Catalpa ovata and Pseudolysimachion lingifolium, exhibits anti-inflammatory, antinociceptic, anti-oxidant, hepatoprotective, and cytostatic activities. We characterized the in vitro metabolic pathways of catalposide to predict its pharmacokinetics. Catalposide was metabolized to catalposide sulfate (M1), 4-hydroxybenzoic acid (M2), 4-hydroxybenzoic acid glucuronide (M3), and catalposide glucuronide (M4) by human hepatocytes, liver S9 fractions, and intestinal microsomes. M1 formation from catalposide was catalyzed by sulfotransferases (SULTs) 1C4, SULT1A1*1, SULT1A1*2, and SULT1E1. Catalposide glucuronidation to M4 was catalyzed by gastrointestine-specific UDP-glucuronosyltransferases (UGTs) 1A8 and UGT1A10; M4 was not detected after incubation of catalposide with human liver preparations. Hydrolysis of catalposide to M2 was catalyzed by carboxylesterases (CESs) 1 and 2, and M2 was further metabolized to M3 by UGT1A6 and UGT1A9 enzymes. Catalposide was also metabolized in extrahepatic tissues; genetic polymorphisms of the carboxylesterase (CES), UDP-glucuronosyltransferase (UGT), and sulfotransferase (SULT) enzymes responsible for catalposide metabolism may cause inter-individual variability in terms of catalposide pharmacokinetics.
Preparation and Characterization of Oxidized Inulin Hydrogel for Controlled Drug Delivery
Authors: Afinjuomo Franklin , Fouladian Paris , Parikh Ankit , Barclay Thomas G. , Song Yunmei , Garg Sanjay
Published: July 2019

Inulin-based hydrogels are useful carriers for the delivery of drugs in the colon-targeted system and in other biomedical applications. In this project, inulin hydrogels were fabricated by crosslinking oxidized inulin with adipic acid dihydrazide (AAD) without the use of a catalyst or initiator. The physicochemical properties of the obtained hydrogels were further characterized using different techniques, such as swelling experiments, in vitro drug release, degradation, and biocompatibility tests. The crosslinking was confirmed with Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). In vitro releases of 5-fluorouracil (5FU) from the various inulin hydrogels was enhanced in acidic conditions (pH 5) compared with physiological pH (pH 7.4). In addition, blank gels did not show any appreciable cytotoxicity, whereas 5FU-loaded hydrogels demonstrated efficacy against HCT116 colon cancer cells, which further confirms the potential use of these delivery platforms for direct targeting of 5-FU to the colon.
Reduction in Use of Risperidone for Dementia in Australia Following Changed Guidelines
Authors: Kalisch Ellett Lisa M , Moffat Anna K , Gadzhanova Svetla , Pratt Nicole L , Apajee Jemisha , Woodward Michael , Roughead Elizabeth E
Published: July 2019

Background: Risperidone is the only antipsychotic approved in Australia for the management of the behavioural and psychological symptoms of dementia (BPSD). In June 2015, the Australian Government Therapeutic Goods Administration (TGA) amended the indication to restrict use in BPSD to patients with Alzheimer’s dementia for a maximum twelve-week duration. We aimed to determine whether the rate and duration of risperidone use for BPSD decreased following the regulatory changes. Methods: we conducted a study using the Australian Government Department of Veterans’ Affairs administrative claims data and Pharmaceutical Benefits Scheme (PBS) 10% sample data. We included people aged 65 years or older and compared the rate and duration of risperidone use before and after the TGA labelling changes. Results: There was a sustained decrease in the trend of risperidone use for BPSD following the TGA labelling changes, with a monthly decrease of 1.7% in the aged care population, 0.5% in the community living population and 1.5% in the general older Australian population. Overall, in the 24 months post the TGA changes the reduction in the rate of use of risperidone ranged from 20% to 28% lower than compared to what the rate would have been without the TGA changes. The median duration of use of risperidone in aged-care residents decreased from 338 days in the year prior to the TGA labelling changes, to 240 days per person in the year after the changes. Conclusion: The TGA labelling changes were associated with a significant reduction in the rate of use of risperidone for BPSD in veterans living in both the aged care and community settings, and in the general older Australian population. The labelling changes were also associated with a reduced duration of risperidone use in aged care residents, although for most people the duration of use still exceeded the recommended 12-week maximum duration.
Kinetic Equations for Particle Clusters Differing in Shape and the H-theorem
Authors: Adzhiev Sergey , Batishcheva Janina , Melikhov Igor , Vedenyapin Victor
Published: July 2019

The question of constructing models for the evolution of clusters that differ in shape based on the Boltzmann’s H-theorem is investigated. The first, simplest kinetic equations are proposed and their properties are studied: the conditions for fulfilling the H-theorem (the conditions for detailed and semidetailed balance). These equations are to generalize the classical coagulation–fragmentation type equations for cases when not only mass but also particle shape is taken into account. To construct correct (physically grounded) kinetic models, the fulfillment of the condition of detailed balance is shown to be necessary to monitor, since it is proved that for accepted frequency functions, the condition of detailed balance is fulfilled and the H-theorem is valid. It is shown that for particular and very important cases, the H-theorem holds: the fulfillment of the Arrhenius law and the additivity of the activation energy for interacting particles are found to be essential. In addition, based on the connection of the principle of detailed balance with the Boltzmann equation for the probability of state, the expressions for the reaction rate coefficients are obtained.
Variations of Secondary Metabolites among Natural Populations of Sub-Antarctic Ranunculus Species Suggest Functional Redundancy and Versatility
Authors: Labarrere Bastien , Prinzing Andreas , Dorey Thomas , Chesneau Emeline , Hennion Françoise
Published: July 2019

Plants produce a high diversity of metabolites which help them sustain environmental stresses and are involved in local adaptation. However, shaped by both the genome and the environment, the patterns of variation of the metabolome in nature are difficult to decipher. Few studies have explored the relative parts of geographical region versus environment or phenotype in metabolomic variability within species and none have discussed a possible effect of the region on the correlations between metabolites and environments or phenotypes. In three sub-Antarctic Ranunculus species, we examined the role of region in metabolite differences and in the relationship between individual compounds and environmental conditions or phenotypic traits. Populations of three Ranunculus species were sampled across similar environmental gradients in two distinct geographical regions in îles Kerguelen. Two metabolite classes were studied, amines (quantified by high-performance liquid chromatography and fluorescence spectrophotometry) and flavonols (quantified by ultra-high-performance liquid chromatography with triple quadrupole mass spectrometry). Depending on regions, the same environment or the same trait may be related to different metabolites, suggesting metabolite redundancy within species. In several cases, a given metabolite showed different or even opposite relations with the same environmental condition or the same trait across the two regions, suggesting metabolite versatility within species. Our results suggest that metabolites may be functionally redundant and versatile within species, both in their response to environments and in their relation with the phenotype. These findings open new perspectives for understanding evolutionary responses of plants to environmental changes.
Leaf Traits That Contribute to Differential Ozone Response in Ozone-Tolerant and Sensitive Soybean Genotypes
Authors: Bailey Amanda , Burkey Kent , Taggart Matthew , Rufty Thomas
Published: July 2019

Ozone (O3) is a phytotoxic air pollutant that limits crop productivity. Breeding efforts to improve yield under elevated O3 conditions will benefit from understanding the mechanisms that contribute to O3 tolerance. In this study, leaf gas exchange and antioxidant metabolites were compared in soybean genotypes (Glycine max (L.) Merr) differing in ozone sensitivity. Mandarin (Ottawa) (O3-sensitive) and Fiskeby III (O3-tolerant) plants grown under charcoal-filtered (CF) air conditions for three weeks were exposed for five days to either CF conditions or 70 ppb O3 in continuously stirred tank reactors (CSTRs) in a greenhouse. In the CF controls, stomatal conductance was approximately 36% lower for Fiskeby III relative to Mandarin (Ottawa) while the two genotypes exhibited similar levels of photosynthesis. Ozone exposure induced significant foliar injury on leaves of Mandarin (Ottawa) associated with declines in both stomatal conductance (by 77%) and photosynthesis (by 38%). In contrast, O3 exposure resulted in minimal foliar injury on leaves of Fiskeby III with only a small decline in photosynthesis (by 5%), and a further decline in stomatal conductance (by 30%). There was a general trend towards higher ascorbic acid content in leaves of Fiskeby III than in Mandarin (Ottawa) regardless of treatment. The results confirm Fiskeby III to be an O3-tolerant genotype and suggest that reduced stomatal conductance contributes to the observed O3 tolerance through limiting O3 uptake by the plant. Reduced stomatal conductance was associated with enhanced water-use efficiency, providing a potential link between O3 tolerance and drought tolerance.
Identification of Factors Linked to Higher Water-Deficit Stress Tolerance in Amaranthus hypochondriacus Compared to Other Grain Amaranths and A. hybridus, Their Shared Ancestor
Authors: González-Rodríguez Tzitziki , Cisneros-Hernández Ismael , Acosta Bayona Jonathan , Ramírez-Chavez Enrique , Martínez-Gallardo Norma , Mellado-Mojica Erika , López-Pérez Mercedes G. , Molina-Torres Jorge , Délano-Frier John
Published: July 2019

Water deficit stress (WDS)-tolerance in grain amaranths (Amaranthus hypochondriacus, A. cruentus and A. caudatus), and A. hybridus, their presumed shared ancestor, was examined. A. hypochondriacus was the most WDS-tolerant species, a trait that correlated with an enhanced osmotic adjustment (OA), a stronger expression of abscisic acid (ABA) marker genes and a more robust sugar starvation response (SSR). Superior OA was supported by higher basal hexose (Hex) levels and high Hex/sucrose (Suc) ratios in A. hypochondriacus roots, which were further increased during WDS. This coincided with increased invertase, amylase and sucrose synthase activities and a strong depletion of the starch reserves in leaves and roots. The OA was complemented by the higher accumulation of proline, raffinose, and other probable raffinose-family oligosaccharides of unknown structure in leaves and/or roots. The latter coincided with a stronger expression of Galactinol synthase 1 and Raffinose synthase in leaves. Increased SnRK1 activity and expression levels of the class II AhTPS9 and AhTPS11 trehalose phosphate synthase genes, recognized as part of the SSR network in Arabidopsis, were induced in roots of stressed A. hypochondriacus. It is concluded that these physiological modifications improved WDS in A. hypochondriacus by raising its water use efficiency.
Chitosan/Glycosaminoglycan Scaffolds: The Role of Silver Nanoparticles to Control Microbial Infections in Wound Healing
Authors: Sandri Giuseppina , Miele Dalila , Faccendini Angela , Bonferoni Maria Cristina , Rossi Silvia , Grisoli Pietro , Taglietti Angelo , Ruggeri Marco , Bruni Giovanna , Vigani Barbara , Ferrari Franca
Published: July 2019

Cutaneous wounds represent a major issue in medical care, with approximately 300 million chronic and 100 million traumatic wound patients worldwide, and microbial infections slow the healing process. The aim of this work was to develop electrospun scaffolds loaded with silver nanoparticles (AgNPs) to enhance cutaneous healing, preventing wound infections. AgNPs were directly added to polymeric blends based on chitosan (CH) and pullulan (PUL) with hyaluronic acid (HA) or chondroitin sulfate (CS) to be electrospun obtaining nanofibrous scaffolds. Moreover, a scaffold based on CH and PUL and loaded with AgNPs was prepared as a comparison. The scaffolds were characterized by chemico–physical properties, enzymatic degradation, biocompatibility, and antimicrobial properties. All the scaffolds were based on nanofibers (diameters about 500 nm) and the presence of AgNPs was evidenced by TEM and did not modify their morphology. The scaffold degradation was proven by means of lysozyme. Moreover, the AgNPs loaded scaffolds were characterized by a good propensity to promote fibroblast proliferation, avoiding the toxic effect of silver. Furthermore, scaffolds preserved AgNP antimicrobial properties, although silver was entrapped into nanofibers. Chitosan/chondroitin sulfate scaffold loaded with AgNPs demonstrated promotion of fibroblast proliferation and to possess antimicrobial properties, thus representing an interesting tool for the treatment of chronic wounds.
Synthesis of Double-Shelled Hollow Inorganic Nanospheres through Block Copolymer-Metal Coordination and Atomic Layer Deposition
Authors: Yan Nina , Guan Qingbao , Yang Zhiming , Feng Min , Jiang Xizhi , Liu Jun , Xu Lei
Published: July 2019

Double-shelled hollow (DSH) structures with varied inorganic compositions are confirmed to have improved performances in diverse applications, especially in lithium ion battery. However, it is still of great challenge to obtain these complex nanostructures with traditional hard templates and solution-based route. Here we report an innovative pathway for the preparation of the DSH nanospheres based on block copolymer self-assembly, metal–ligand coordination and atomic layer deposition. Polymeric composite micelles derived from amphiphilic block copolymers and ferric ions were prepared with heating-enabled micellization and metal–ligand coordination. The DSH nanospheres with Fe2O3 stands inner and TiO2 outer the structures can be obtained with atomic layer deposition of a thin layer of TiO2 followed with calcination in air. The coordination was carried out at room temperature and the deposition was performed at the low temperature of 80 °C, thus providing a feasible fabrication strategy for DSH structures without destruction of the templates. The cavity and the outer layer of the structures can also be simply tuned with the utilized block copolymers and the deposition cycles. These DSH inorganic nanospheres are expected to find vital applications in battery, catalysis, sensing and drug delivery, etc.
Improvement of Mechanical Properties and Self-Healing Efficiency by Ex-Situ Incorporation of TiO2 Nanoparticles to a Waterborne Poly(Urethane-Urea)
Authors: Díez-García Iñigo , Eceiza Arantxa , Tercjak Agnieszka
Published: July 2019

This research work was focused on the incorporation of TiO2 nanoparticles into synthesized solvent-free waterborne poly(urethane-urea) (WPUU) based on hydrophilic poly(ethylene oxide) (PU0) in order to improve both the mechanical properties and self-healing effectiveness of a polymer matrix. The incorporation of TiO2 nanoparticles resulted in a successful enhancement of the mechanical properties of nanocomposite films when compared to PU0. Simultaneously, the obtained nanocomposite films did not only maintain the self-healing ability of the PU0 film, measured by means of mechanical properties after successive cutting/recovery cycles, but they also showed a higher self-healing efficiency than the PU0 film. Moreover, the well-dispersed TiO2 nanoparticles, visualized by atomic force microscopy (AFM), kept their conductive properties when embedded in the PU0 matrix, as was confirmed by electrostatic force microscopy (EFM). This research work described a simple and industrially appealing way to control the dispersion of commercially available TiO2 nanoparticles in waterborne poly(urethane-urea) for the designing of inorganic/organic hybrid nanocomposites with enhanced mechanical properties and self-healing efficiency, in which TiO2 nanoparticles preserved their conductive properties within the polymer matrix.
Magnetic Fluorescence Molecularly Imprinted Polymer Based on FeOx/ZnS Nanocomposites for Highly Selective Sensing of Bisphenol A
Authors: Zhang Xin , Yang Shu , Chen Weijie , Li Yansong , Wei Yuping , Luo Aiqin
Published: July 2019

In this study, magnetic fluorescence molecularly imprinted polymers were fabricated and used for the selective separation and fluorescence sensing of trace bisphenol A (BPA) in environmental water samples. The carboxyl-functionalized FeOx magnetic nanoparticles were conjugated with mercaptoethylamine-capped Mn2+ doped ZnS quantum dots to prepare magnetic FeOx and ZnS quantum dot nanoparticles (FeOx/ZnS NPs). Additionally, molecular imprinting on the FeOx/ZnS NPs was employed to synthesize core-shell molecularly imprinted polymers. The resulting nanoparticles were well characterized using transmission electron microscopy, Fourier transform infrared spectra, vibrating sample magnetometer and fluorescence spectra, and the adsorption behavior was investigated. Binding experiments showed that the molecularly imprinted FeOX/ZnS NPs (FeOx/ZnS@MIPs) exhibited rapid fluorescent and magnetic responses, and high selectivity and sensitivity for the detection of bisphenol A (BPA). The maximum adsorption capacity of FeOx/ZnS@MIPs was 50.92 mg·g−1 with an imprinting factor of 11.19. Under optimal conditions, the constructed fluorescence magnetic molecularly imprinted polymers presented good linearity from 0 to 80 ng mL−1 with a detection limit of 0.3626 ng mL−1 for BPA. Moreover, the proposed fluorescence magnetic polymers were successfully applied to on-site magnetic separation and real-time fluorescence analysis of target molecule in real samples.
Synergistic Flame-Retardant Mechanism of Dicyclohexenyl Aluminum Hypophosphite and Nano-Silica
Authors: Zhang Heng , Lu Junliang , Yang Hongyan , Yang Heng , Lang Jinyan , Zhang Qinqin
Published: July 2019

The flame retardant dicyclohexenyl aluminum hypophosphite (ADCP) and nano-silica are added to PA66 to improve flame retardant property of the composite. The flame-retardant property of the composite is tested via oxygen index test, vertical burning test, and cone calorimetry test. Combustion residues are tested using scanning electron microscopy, EDS spectroscopy, and Fourier infrared analysis. Results show that flame-retardant ADCP can effectively promote the formation of a porous carbon layer on the combustion surface of PA66. Nano-silica easily migrates to the material surface to improve the oxidation resistance of the carbon layer and the density of the carbon layer’s structure. It can also effectively prevent heat, flammable gases, and oxygen from entering the flame zone and enhance the flame retardant properties of ADCP.
Enhanced Electrical Conductivity of Carbon Nanotube-Based Elastomer Nanocomposites Prepared by Microwave Curing
Authors: Herren Blake , Larson Preston , Saha Mrinal , Liu Yingtao
Published: July 2019

Nanocomposites consisting of polydimethylsiloxane (PDMS) and well-dispersed carbon nanotubes (CNT) can be cured by microwave radiation within a minute, forming a conductive network within the cured materials. Microwave irradiation delivers energy directly to the inner core of the nanocomposites by heating CNTs and initiating rapid polymerization of the elastomer. In this paper, nanocomposites were fabricated with CNT loadings between 0.5 wt.%–2.5 wt.% via microwave irradiation. Key properties of the nanocomposites including electrical conductivity, microstructures, CNT distribution, density, and surface effects were all characterized. The properties of microwave-cured nanocomposites were compared with those manufactured by the thermal method using a conventional oven. The microwave-curing method substantially increased the electrical conductivity of the nanocomposites due to the improved nanoparticle dispersion and likely CNT alignment. Optimal microwave-curing parameters were identified to further improve the conductivity of the nanocomposites with lowest CNT loading. A conductivity enhancement of 142.8% over thermally cured nanocomposites was achieved for nanocomposites with 1 wt.% CNTs cured via one-step microwave irradiation.
Amphiphilic Acrylic Nanoparticles Containing the Poloxamer Star Bayfit® 10WF15 as Ophthalmic Drug Carriers
Authors: Gómez-Ballesteros Miguel , Andrés-Guerrero Vanessa , Parra Francisco , Marinich Jorge , de-las-Heras Beatriz , Molina-Martínez Irene , Vázquez-Lasa Blanca , San Román Julio , Herrero-Vanrell Rocío
Published: July 2019

Topical application of drops containing ocular drugs is the preferred non-invasive route to treat diseases that affect the anterior segment of the eye. However, the formulation of eye drops is a major challenge for pharmacists since the access of drugs to ocular tissues is restricted by several barriers. Acetazolamide (ACZ) is a carbonic anhydrase inhibitor used orally for the treatment of ocular hypertension in glaucoma. However, large ACZ doses are needed which results in systemic side effects. Recently, we synthesized copolymers based on 2-hydroxyethyl methacrylate (HEMA) and a functionalized three-arm poloxamer star (Bayfit-MA). The new material (HEMA/Bayfit-MA) was engineered to be transformed into nanoparticles without the use of surfactants, which represents a significant step forward in developing new ophthalmic drug delivery platforms. Acetazolamide-loaded nanocarriers (ACZ-NPs) were prepared via dialysis (224 ± 19 nm, −17.2 ± 0.4 mV). The in vitro release rate of ACZ was constant over 24 h (cumulative delivery of ACZ: 83.3 ± 8.4%). Following standard specifications, ACZ-NPs were not cytotoxic in vitro in cornea, conjunctiva, and macrophages. In normotensive rabbits, ACZ-NPs generated a significant intraocular pressure reduction compared to a conventional solution of ACZ (16.4% versus 9.6%) with the same dose of the hypotensive drug (20 µg). In comparison to previously reported studies, this formulation reduced intraocular pressure with a lower dose of ACZ. In summary, HEMA:Bayfit-MA nanoparticles may be a promising system for ocular topical treatments, showing an enhanced ocular bioavailability of ACZ after a single instillation on the ocular surface.
Gamma-Irradiation-Prepared Low Molecular Weight Hyaluronic Acid Promotes Skin Wound Healing
Authors: Huang Yu-Chih , Huang Kuen-Yu , Lew Wei-Zhen , Fan Kang-Hsin , Chang Wei-Jen , Huang Haw-Ming
Published: July 2019

In this study, we prepared low-molecular-weight hyaluronic acid (LMWHA) powder by γ-irradiation. The chemical and physical properties of γ-irradiated LMWHA and the in vitro cellular growth experiments with γ-irradiated LMWHA were analyzed. Then, hyaluronic acid exposed to 20 kGy of γ-irradiation was used to fabricate a carboxymethyl cellulose (CMC)/LMWHA fabric for wound dressing. Our results showed that γ-irradiated LMWHA demonstrated a significant alteration in carbon–oxygen double bonding and can be detected using nuclear magnetic resonance and ultraviolet (UV)-visible (Vis) spectra. The γ-irradiated LMWHA exhibited strain rate-dependent Newton/non-Newton fluid biphasic viscosity. The viability of L929 skin fibroblasts improved upon co-culture with γ-irradiated LMWHA. In the in vivo animal experiments, skin wounds covered with dressings prepared by γ-irradiation revealed acceleration of wound healing after two days of healing. The results suggest that γ-irradiated LMWHA could be a potential source for the promotion of skin wound healing.
Complementary Assessment of Commercial Photoluminescent Pigments Printed on Cotton Fabric
Authors: Gorgieva Selestina , Virant Natalija , Ojstršek Alenka
Published: July 2019

The presented study focuses on photoluminescent pigments applied on cotton fabric by a screen-printed procedure using polydimethylsiloxane (PDMS) as a binder. Microscopic data depicts irregular shapes and relatively wide size distribution (3–80 µm) of pigments. Regarding composition, the Energy-Dispersive X-ray (EDX) and Fourier Transform Infrared (FTIR) spectroscopy data complement findings suggesting the presence of Eu-doped strontium aluminate in the yellow-green, calcium aluminate in the violet pigment, and metal oxides in the blue pigment. The optical properties of pigment-enriched PDMS-coated cotton fabric were assessed and reflectance intensity was found to be concentration-dependent only in the blue pigment. The luminescence decay data show that luminescence intensity decreased with the reduction of pigment concentration in the following order, yellow-green > blue > violet pigments. Relying on absorption and emission data of powdered pigments, the confocal microscopy enables visualization of the pigments’ distribution within a 3D image projection. This identifies the most homogeneous distribution in the case of the blue pigment, as well as the presence of a continuous fluorescing signal in the z projection when 5% pigment was used. This was, for the first time, presented as a powerful tool for non-destructive visualization of photoluminescent pigments’ spatial distribution when printed on textile (cotton) fabric. Finally, the photoluminescent PDMS coating demonstrates high washing and abrasion resistance, contributing to overall functionality of printed cotton fabrics when commercial types of pigments are applied.
The Effect of Degradation of Soda Lignin Using Pd/SO42−/ZrO2 as a Catalyst: Improved Reactivity and Antioxidant Activity
Authors: Zhang Shengming , Fang Guizhen , Chen Haitao , Lang Qian
Published: July 2019

To the value-added application of the soda lignin by improving its reactivity and antioxidant activity, a self-made Pd/SO42−/ZrO2 catalyst was used to catalyze the degradation reaction of soda lignin. The catalyst was loaded with the palladium of 1.47 wt.% while retaining the super acidity of SO42−/ZrO2. The reaction condition was determined as follows: the dioxane-water solution was selected as the reaction solution, the addition amount of the catalyst was 5 wt.% of the soda lignin, the system was heated at 100 °C for 4 h under a hydrogen pressure of 3 MPa. The reactivity of the catalyzed-soda lignin compared to the soda lignin before the reaction was significantly improved: the values of phenolic hydroxyl groups and total hydroxyl groups were increased by 35.3% and 97.1%, respectively, and the value of methoxy groups was decreased by 13%. Approximately 63.3% of the β-O-4 bonds were cleaved, which resulted in a reduction of the weight average molecular weight from 8200 g·mol−1 to 4900 g·mol−1. At the same time, the EC50 values of the catalyzed-soda lignin on DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS+ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radicals scavenging were decreased by 20.6% and 32.6%, respectively, and the reducing power of catalyzed-soda lignin at the absorption value of 0.5 was increased by 10.5%. The Pd/SO42−/ZrO2 catalyst works by breaking the β-O-4 linkages and degrading the methoxy groups. The catalyzed-soda lignin exhibits the possibility of being used as the antioxidants, grafting precursors, adhesive additives, and raw materials for lignin/polymer composites.
Printability and Tensile Performance of 3D Printed Polyethylene Terephthalate Glycol Using Fused Deposition Modelling
Authors: Guessasma Sofiane , Belhabib Sofiane , Nouri Hedi
Published: July 2019

Polyethylene terephthalate glycol (PETG) is a thermoplastic formed by polyethylene terephthalate (PET) and ethylene glycol and known for his high impact resistance and ductility. The printability of PETG for fused deposition modelling (FDM) is studied by monitoring the filament temperature using an infra-red camera. The microstructural arrangement of 3D printed PETG is analysed by means of X-ray micro-tomography and tensile performance is investigated in a wide range of printing temperatures from 210 °C to 255 °C. A finite element model is implemented based on 3D microstructure of the printed material to reveal the deformation mechanisms and the role of the microstructural defects on the mechanical performance. The results show that PETG can be printed within a limited range of printing temperatures. The results suggest a significant loss of the mechanical performance due to the FDM processing and particularly a substantial reduction of the elongation at break is observed. The loss of this property is explained by the inhomogeneous deformation of the PETG filament. X-ray micro-tomography results reveal a limited amount of process-induced porosity, which only extends through the sample thickness. The FE predictions point out the combination of local shearing and inhomogeneous stretching that are correlated to the filament arrangement within the plane of construction.
Anionic Polymerization of β-Butyrolactone Initiated with Sodium Phenoxides. The Effect of the Initiator Basicity/Nucleophilicity on the ROP Mechanism
Authors: Domiński Adrian , Konieczny Tomasz , Zięba Magdalena , Klim Magdalena , Kurcok Piotr
Published: July 2019

It was shown that selected sodium phenoxide derivatives with different basicity and nucleophilicity, such as sodium p-nitrophenoxide, p-chlorophenoxide, 1-napthoxide, phenoxide and p-methoxyphenoxide, are effective initiators in anionic ring-opening polymerization (AROP) of β-butyrolactone in mild conditions. It was found that phenoxides as initiators in anionic ring-opening polymerization of β-butyrolactone behave as strong nucleophiles, or weak nucleophiles, as well as Brønsted bases. The resulting polyesters possessing hydroxy, phenoxy and crotonate initial groups are formed respectively by the attack of phenoxide anion at (i) C2 followed by an elimination reaction with hydroxide formation, (ii) C4 and (iii) abstraction of acidic proton at C3. The obtained poly(3-hydroxybutyrate) possesses carboxylate growing species. The ratio of the observed initial groups strongly depends on the basicity and nucleophilicity of the sodium phenoxide derivative used as initiator. The proposed mechanism of this polymerization describes the reactions leading to formation of observed end groups. Moreover, the possibility of formation of a crotonate group during the propagation step of this polymerization is also discussed.
Influence of Co-Catalysts and Polymerization Conditions on Properties of Poly(anhydride-alt-epoxide)s from ROCOP Using Salen Complexes with Different Metals
Authors: Proverbio Matteo , Galotto Galotto Nella , Losio Simona , Tritto Incoronata , Boggioni Laura
Published: July 2019

Cyclohexene oxide (CHO) and phthalic anhydride (PA) have been reacted in the presence of commercial salen–type complexes with different metals Cr (1), Al (2), and Mn (3) in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl) and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) as co-catalysts to obtain alternating poly(PA-alt-CHO)s by ring-opening copolymerization (ROCOP). The effect of different reaction conditions (pre-contact between catalyst and co-catalyst, polymerization time) on the productivity, molecular weight and glass transition temperature has been evaluated. By using a 24 h pre-contact, the aliphatic polyesters obtained were characterized by high molecular weight (Mn > 15 kg/mol) and glass transition temperature (Tg) up to 146 °C; the more sustainable metals Al and Mn in the presence of PPNCl give comparable results to Cr. Moreover, biodegradability data of these polyesters and the study of the microstructure reveal that the biodegradability is influenced more by the type of chain linkages rather than by the molecular weight of the polyesters.