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  • 1
    Online Resource
    Online Resource
    Poly (vinyl alcohol)-oligophosphonate eco-friendly composites with improved reaction-to-fire properties
    Elsevier BV ; 2020
    In:  Composites Communications Vol. 22 ( 2020-12), p. 100505-
    Details
    In: Composites Communications, Elsevier BV, Vol. 22 ( 2020-12), p. 100505-
    Type of Medium: Online Resource
    ISSN: 2452-2139
    URL: Article
    DOI: 10.1016/j.coco.2020.100505
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2866635-5
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  • 2
    Online Resource
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    The Spatio-Temporal Distribution of the Freshwater Bivalves Corbicula fluminea and Dreissena polymorpha in the Lower Sector of the Danube River and the Danube Delta
    MDPI AG ; 2023
    In:  Sustainability Vol. 15, No. 11 ( 2023-05-24), p. 8526-
    Details
    In: Sustainability, MDPI AG, Vol. 15, No. 11 ( 2023-05-24), p. 8526-
    Abstract: The objective of this study is to provide an updated account of the distribution history of two invasive molluscs, Corbicula fluminea and Dreissena polymorpha, both in Europe and worldwide. In addition to this, the study also intends to review their ecological requirements to gain a better understanding of their invasive potential and distribution dynamics. Specifically, the study focuses on updating the distribution and ecological characteristics of these freshwater bivalves in the lower sector of the Danube River and the lakes of the Danube Delta. The purpose is to better understand their invasive and distribution dynamics and to develop effective measures to limit their spread in the future. To achieve this, environmental proxies such as sediment particle size and Total Organic Carbon (TOC) concentrations were used to assess their tolerances. However, the results did not show a significant correlation between the densities of these bivalves and the analyzed environmental parameters. Despite this, the species were found in high densities and formed well-developed benthic communities in some stations. The study contributes to the understanding of the invasiveness of these bivalve species and their distribution range dynamics. Nonetheless, further investigation is required to fully comprehend the role of environmental parameters in their distribution. The study covers the period between 2010 and 2020 and focuses on the lower Danube River sector and Danube Delta.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su15118526
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2518383-7
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  • 3
    Online Resource
    Online Resource
    Effects of Blue-Light Laser Irradiation on the Enzymatic Activities and Sporulation of Trichoderma atroviride Grown on Rice Husks
    MDPI AG ; 2023
    In:  Applied Sciences Vol. 13, No. 16 ( 2023-08-12), p. 9191-
    Details
    In: Applied Sciences, MDPI AG, Vol. 13, No. 16 ( 2023-08-12), p. 9191-
    Abstract: Light is known to impact various aspects of Trichoderma, with possible implications for industrial and agricultural applications. In this study, we investigated the irradiation of Trichoderma atroviride with blue light using a laser source system. We determined the cellulase and protease activities and the effects of UV–Vis absorption of the filtrated culture on conidia formation, dimension, and behavior, and on the apparent chlamydospore abundance, as a function of irradiation duration, dose of irradiation, and moment of irradiation. We show that the effects on the enzymatic activities range from positive to neutral to negative. Compared with previous studies, our stimulation with light does not show a drastic negative effect on the cellulase (CMC-ase) activity, but it seems to delay the maximum activity over time. The effects on the proteases are partially in agreement with the only previous study reported for the light effects on protease activity. The number of conidia is increased upon irradiation, representing an expected behavior, and we show for the first time to the best of our knowledge that the conidia dimensions and chlamydospore number also increase. Our data also suggest that the highest dose resulted in the conidia clustering around the liquid–air interface, suggesting an increased hydrophobic character.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app13169191
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704225-X
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  • 4
    Online Resource
    Online Resource
    Kinetics of chitosan coagulation from aqueous solutions
    Wiley ; 2018
    In:  Journal of Applied Polymer Science Vol. 135, No. 16 ( 2018-04-20)
    Details
    In: Journal of Applied Polymer Science, Wiley, Vol. 135, No. 16 ( 2018-04-20)
    Abstract: In this study, we investigated the kinetics of chitosan hydrogel formation from aqueous chitosan solutions with sodium hydroxide (NaOH) as the coagulant. Two sets of experiments were performed, one in a parallelepiped cell and the other with cylindrical chitosan solution extrudates. The coagulation occurred by the neutralization of the protonated amino groups ( ) present in the chitosan chains, with the kinetics being controlled by NaOH transport toward the gelification zone. In this study, we confirmed the appropriateness of Fick's second law to describe NaOH transport, considering the instantaneous reaction between the NaOH and  groups. The experimental data were used to determine the NaOH diffusion coefficient in gels having different chitosan concentrations. The diffusion coefficient values obtained from the cylindrical coagulation data were lower than those determined for linear coagulation because of the influences of transport geometry and gel structure, respectively. Accordingly, in fiber coagulation calculations, it is recommended to use diffusion coefficient values determined from cylindrical coagulation studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46062.
    Type of Medium: Online Resource
    ISSN: 0021-8995 , 1097-4628
    URL: Issue
    URL: Article
    DOI: 10.1002/app.v135.16
    DOI: 10.1002/app.46062
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 1491105-X
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  • 5
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    Online Resource
    Synergism between Graphene and Molecularly Imprinted Polymers in Developing Electrochemical Sensors for Agri-Food and Environmental Analyses
    MDPI AG ; 2023
    In:  Chemosensors Vol. 11, No. 7 ( 2023-07-07), p. 380-
    Details
    In: Chemosensors, MDPI AG, Vol. 11, No. 7 ( 2023-07-07), p. 380-
    Abstract: In recent years, new sensor-based technologies have been developed to meet the demand for rapid and accurate analysis of food and environment, as food safety and environmental monitoring are very important concerns nowadays. In this context, considerable attention has been paid to the development and design of electrochemical sensors, as these offer a number of advantages, such as portability, ease of use, low costs and fast response times. Molecularly imprinted polymers (MIPs) are robust synthetic polymers with special cavities designed for a target molecule, and they are used as selective tools through a mechanism of molecular recognition. Graphene is a 2D crystalline carbon that forms either a single or a coupled layer of hexagonally arranged carbon atoms and is referred to as a “wonder material”. The use of these two structures in the development of electrochemical sensors gives the newly created analytical tool enhanced properties, such as improved sensitivity and selectivity, low detection limit, good stability and reusability. This review presents an overview of the recent research regarding the use of MIPs and graphene in the development of electrochemical sensors for food and environmental analyses, critically discusses the pros and cons, and gives perspectives for further developments in this field.
    Type of Medium: Online Resource
    ISSN: 2227-9040
    URL: Article
    DOI: 10.3390/chemosensors11070380
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704218-2
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  • 6
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    Chitosan Membranes Containing Plant Extracts: Preparation, Characterization and Antimicrobial Properties
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 10 ( 2023-05-12), p. 8673-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 10 ( 2023-05-12), p. 8673-
    Abstract: The main strategy of this study was to combine the traditional perspective of using medicinal extracts with polymeric scaffolds manufactured by an engineering approach to fabricate a potential dressing product with antimicrobial properties. Thus, chitosan-based membranes containing S. officinalis and H. perforatum extracts were developed and their suitability as novel dressing materials was investigated. The morphology of the chitosan-based films was assessed by scanning electron microscopy (SEM) and the chemical structure characterization was performed via Fourier transform infrared spectroscopy (FTIR). The addition of the plant extracts increased the sorption capacity of the studied fluids, mainly at the membrane with S. officinalis extract. The membranes with 4% chitosan embedded with both plant extracts maintained their integrity after being immersed for 14 days in incubation media, especially in PBS. The antibacterial activities were determined by the modified Kirby–Bauer disk diffusion method for Gram-positive (S. aureus ATCC 25923, MRSA ATCC 43300) and Gram-negative (E. coli ATCC 25922, P. aeruginosa ATCC 27853) microorganisms. The antibacterial property was enhanced by incorporating the plant extracts into chitosan films. The outcome of the study reveals that the obtained chitosan-based membranes are promising candidates to be used as a wound dressing due to their good physico-chemical and antimicrobial properties.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms24108673
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 7
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    Online Resource
    Tunable Properties via Composition Modulations of Poly(vinyl alcohol)/Xanthan Gum/Oxalic Acid Hydrogels
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 7 ( 2022-04-04), p. 2657-
    Details
    In: Materials, MDPI AG, Vol. 15, No. 7 ( 2022-04-04), p. 2657-
    Abstract: The design of hydrogel networks with tuned properties is essential for new innovative biomedical materials. Herein, poly(vinyl alcohol) and xanthan gum were used to develop hydrogels by the freeze/thaw cycles method in the presence of oxalic acid as a crosslinker. The structure and morphology of the obtained hydrogels were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and swelling behavior. The SEM analysis revealed that the surface morphology was mostly affected by the blending ratio between the two components, namely, poly(vinyl alcohol) and xanthan gum. From the swelling study, it was observed that the presence of oxalic acid influenced the hydrophilicity of blends. The hydrogels based on poly(vinyl alcohol) without xanthan gum led to structures with a smaller pore diameter, a lower swelling degree in pH 7.4 buffer solution, and a higher elastic modulus. The antimicrobial activity of the prepared hydrogels was tested and the results showed that the hydrogels conferred antibacterial activity against Gram positive bacteria (Staphylococcus aureus 25923 ATCC) and Gram negative bacteria (Escherichia coli 25922 ATCC).
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma15072657
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2487261-1
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  • 8
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    A Retrospective Assessment of Sputum Samples and Antimicrobial Resistance in COVID-19 Patients
    MDPI AG ; 2023
    In:  Pathogens Vol. 12, No. 4 ( 2023-04-19), p. 620-
    Details
    In: Pathogens, MDPI AG, Vol. 12, No. 4 ( 2023-04-19), p. 620-
    Abstract: Data on bacterial or fungal pathogens and their impact on the mortality rates of Western Romanian COVID-19 patients are scarce. As a result, the purpose of this research was to determine the prevalence of bacterial and fungal co- and superinfections in Western Romanian adults with COVID-19, hospitalized in in-ward settings during the second half of the pandemic, and its distribution according to sociodemographic and clinical conditions. The unicentric retrospective observational study was conducted on 407 eligible patients. Expectorate sputum was selected as the sampling technique followed by routine microbiological investigations. A total of 31.5% of samples tested positive for Pseudomonas aeruginosa, followed by 26.2% having co-infections with Klebsiella pneumoniae among patients admitted with COVID-19. The third most common Pathogenic bacteria identified in the sputum samples was Escherichia coli, followed by Acinetobacter baumannii in 9.3% of samples. Commensal human pathogens caused respiratory infections in 67 patients, the most prevalent being Streptococcus penumoniae, followed by methicillin-sensitive and methicillin-resistant Staphylococcus aureus. A total of 53.4% of sputum samples tested positive for Candida spp., followed by 41.1% of samples with Aspergillus spp. growth. The three groups with positive microbial growth on sputum cultures had an equally proportional distribution of patients admitted to the ICU, with an average of 30%, compared with only 17.3% among hospitalized COVID-19 patients with negative sputum cultures (p = 0.003). More than 80% of all positive samples showed multidrug resistance. The high prevalence of bacterial and fungal co-infections and superinfections in COVID-19 patients mandates for strict and effective antimicrobial stewardship and infection control policies.
    Type of Medium: Online Resource
    ISSN: 2076-0817
    URL: Article
    DOI: 10.3390/pathogens12040620
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2695572-6
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  • 9
    Online Resource
    Online Resource
    Fabrication of Poly(vinyl alcohol)/Chitosan Composite Films Strengthened with Titanium Dioxide and Polyphosphonate Additives for Packaging Applications
    MDPI AG ; 2022
    In:  Gels Vol. 8, No. 8 ( 2022-07-28), p. 474-
    Details
    In: Gels, MDPI AG, Vol. 8, No. 8 ( 2022-07-28), p. 474-
    Abstract: Eco-innovation through the development of intelligent materials for food packaging is evolving, and it still has huge potential to improve food product safety, quality, and control. The design of such materials by the combination of biodegradable semi-synthetic polymers with natural ones and with some additives, which may improve certain functionalities in the targeted material, is continuing to attract attention of researchers. To fabricate composite films via casting from solution, followed by drying in atmospheric conditions, certain mass ratios of poly(vinyl alcohol) and chitosan were used as polymeric matrix, whereas TiO2 nanoparticles and a polyphosphonate were used as reinforcing additives. The structural confirmation, surface properties, swelling behavior, and morphology of the xerogel composite films have been studied. The results confirmed the presence of all ingredients in the prepared fabrics, the contact angle of the formulation containing poly(vinyl alcohol), chitosan, and titanium dioxide in its composition exhibited the smallest value (87.67°), whereas the profilometry and scanning electron microscopy enlightened the good dispersion of the ingredients and the quality of all the composite films. Antimicrobial assay established successful antimicrobial potential of the poly(vinyl alcoohol)/chitosan-reinforced composites films against Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. Cytotoxicity tests have revealed that the studied films are non-toxic, presented good compatibility, and they are attractive candidates for packaging applications.
    Type of Medium: Online Resource
    ISSN: 2310-2861
    URL: Article
    DOI: 10.3390/gels8080474
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2813982-3
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  • 10
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    Online Resource
    Phosphorylated Curdlan Gel/Polyvinyl Alcohol Electrospun Nanofibres Loaded with Clove Oil with Antibacterial Activity
    MDPI AG ; 2022
    In:  Gels Vol. 8, No. 7 ( 2022-07-13), p. 439-
    Details
    In: Gels, MDPI AG, Vol. 8, No. 7 ( 2022-07-13), p. 439-
    Abstract: Fibrous membranes based on natural polymers obtained by the electrospinning technique are a great choice for wound dressings. In order to promote an efficient wound repair, and to avoid antibiotics, antibacterial plant extracts can be incorporated. In the present work, the new electrospun nanofibre membranes based on monobasic phosphate curdlan (PCurd) and polyvinyl alcohol (PVA) were obtained for the first time. To establish the adequate mixing ratio for electrospinning, the behaviour of the PCurd and PVA mixture was studied by viscometry and rheology. In order to confer antimicrobial activity with the nanofibre membrane, clove essential oil (CEO) was incorporated into the electrospun solution. Well-defined and drop-free nanofibres with a diameter between 157 nm and 110 nm were obtained. The presence of CEO in the obtained nanofibres was confirmed by ATR–FTIR spectroscopy, by the phenolic and flavonoid contents, and by the antioxidant activity of the membranes. In physiological conditions, CEO was released from the membrane after 24 h. The in vivo antimicrobial tests showed a good inhibitory activity against E. coli and higher activity against S. aureus. Furthermore, the viability cell test showed the lack of cytotoxicity of the nanofibre membrane with and without CEO, confirming its potential use in wound treatment.
    Type of Medium: Online Resource
    ISSN: 2310-2861
    URL: Article
    DOI: 10.3390/gels8070439
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2813982-3
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