Browse

You are looking at 1 - 10 of 161 items for :

  • Nanotechnology x
Clear All
Open access

Martin Koller

Abstract

The benefit of biodegradable “green plastics” over established synthetic plastics from petro-chemistry, namely their complete degradation and safe disposal, makes them attractive for use in various fields, including agriculture, food packaging, and the biomedical and pharmaceutical sector. In this context, microbial polyhydroxyalkanoates (PHA) are auspicious biodegradable plastic-like polyesters that are considered to exert less environmental burden if compared to polymers derived from fossil resources.

The question of environmental and economic superiority of bio-plastics has inspired innumerable scientists during the last decades. As a matter of fact, bio-plastics like PHA have inherent economic drawbacks compared to plastics from fossil resources; they typically have higher raw material costs, and the processes are of lower productivity and are often still in the infancy of their technical development. This explains that it is no trivial task to get down the advantage of fossil-based competitors on the plastic market. Therefore, the market success of biopolymers like PHA requires R&D progress at all stages of the production chain in order to compensate for this disadvantage, especially as long as fossil resources are still available at an ecologically unjustifiable price as it does today.

Ecological performance is, although a logical argument for biopolymers in general, not sufficient to make industry and the society switch from established plastics to bio-alternatives. On the one hand, the review highlights that there’s indeed an urgent necessity to switch to such alternatives; on the other hand, it demonstrates the individual stages of the production chain, which need to be addressed to make PHA competitive in economic, environmental, ethical, and performance-related terms. In addition, it is demonstrated how new, smart PHA-based materials can be designed, which meet the customer’s expectations when applied, e.g., in the biomedical or food packaging sector.

Open access

Peter M. Eze, Joy C. Nnanna, Ugochukwu Okezie, Happiness S. Buzugbe, Chika C. Abba, Chidimma R. Chukwunwejim, Festus B. C. Okoye and Charles O. Esimone

Abstract

Endophytic fungi associated with Nigerian plants have recently generated significant interest in drug discovery programmes due to their immense potential to contribute to the discovery of new bioactive compounds. This study was carried out to investigate the secondary metabolites of endophytic fungi isolated from leaves of Newbouldia laevis, Ocimum gratissimum, and Carica papaya. The plants were collected from Agulu, Anambra State, South-East Nigeria. Endophytic fungal isolation, fungal fermentation; and extraction of secondary metabolites were carried out using standard methods. The crude extracts were screened for antimicrobial activities using the agar well diffusion method, and were also subjected to high performance liquid chromatography (HPLC) analysis to identify their constituents. A total of five endophytic fungi was isolated, two from N. laevis (NL-L1 and NL-L2), one from O. gratissimum (SL-L1), and two from C. papaya (PPL-LAC and PPL-LE2). In the antimicrobial assay, the extracts of NL-L2, SL-L1, and PPL-LE2 displayed mild antibacterial activity against both Gram negative and Gram positive test bacteria. PPL-LAC extract showed mild activity only against S. aureus, while no antimicrobial activity was recorded for NL-L1 extract. All the endophytic fungal extracts showed no activity against the test fungi C. albicans and A. fumigatus. HPLC analysis of the fungal extracts revealed the presence of ethyl 4-hydroxyphenyl acetate and ferulic acid in NL-L1; ruspolinone in NL-L2; protocatechuic acid, scytalone, and cladosporin in SL-L1; indole-3-acetic acid and indole-3-carbaldehyde in PPL-LE2; and indole-3-acetic acid in PPL-LAC. The findings of this study revealed the potentials possessed by these plants as source of endophytes that express biological active compounds. These endophytes hold key of possibilities to the discovery of novel molecules for pharmaceutical, agricultural and industrial applications.

Open access

Manuela-Maria Manziuc, Cristina Gasparik, Marius Negucioiu, Mariana Constantiniuc, Alexandru Burde, Ioana Vlas and Diana Dudea

Abstract

Translucent monolithic zirconia is the newest option of zirconia-based ceramics, which aimed to substitute the opaque classic yttria-stabilized tetragonal zirconia polycrystal (Y-TZPs) in more demanding esthetic cases.

The aim of this review was to assess the available literature regarding the optical, chemical and mechanical properties of translucent zirconia ceramics.

This systematic review was developed according to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines. An electronic literature search was undertaken through Medline (National Library of Medicine) via PubMed to identify relevant articles, published in the interval 2010-2018. The search was limited to the English language publications, in vitro studies of color and microstructure of translucent zirconia material.

Yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) has excellent mechanical properties, but its intense white color and high opacity represent an esthetic limit. Cubic zirconia represents a new generation of dental ceramics with molecular structure and physical properties different from the conventional zirconia. Dental manufacturers created new formulations of this restorative material, introducing new cubic varieties of zirconia with improved optical properties. Translucent monolithic zirconia provides a new restorative option that combines strength with improved esthetics, due to its increased translucency. Translucent zirconia is indicated for anterior and posterior restorations but should be used carefully for discolored teeth, because the background color can affect the final esthetic appearance of the restoration.

Open access

Donald K. Martin

Abstract

This paper reports the use of low-frequency ultrasound to influence transport in porous hydrogels with a transducer attached in direct contact with the hydrogel. This is a different configuration than for ultrasound-generating devices utilized previously for enhancing transport of molecules. The advantages of the system reported in this manuscript are that (i) much less acoustic power is required to influence the transport in the hydrogel that is in direct contact with the ultrasonic transducer, and (ii) no cavitation is induced in the hydrogel to influence the transport. This system was first tested in bench-top in vitro experiments by quantifying the transport of gold nanoparticles stimulated by low-frequency ultrasound. Then, to provide an in vivo example for potential biotechology applications, the system was demonstrated to be capable of transporting drugs across the tunics of a rabbit eye into the ocular circulation so as to target the transported drug to the outer retina.

Open access

Evgeni Eltzov, Abri Lavena De Cesarea, ‘Yuen Kei Adarina Low and Robert S. Marks

Abstract

A vast majority of people today spend more time indoors than outdoors. However, the air quality indoors may be as bad as or even worse than the air quality outside. This is due to the continuous circulation of the same air without proper ventilation and filtration systems, causing a buildup of pollutants. As such, indoor air quality monitoring should be considered more seriously. Indoor air quality (IAQ) is a measure of the air quality within and around buildings and relates to the health and comfort of building occupants. To determine the IAQ, computer modeling is done to simulate the air flow and human exposure to the pollutant. Currently, very few instruments are available to measure the indoor air pollution index. In this paper, we will review the list of techniques available for measuring IAQ, but our emphasis will be on indoor air toxicity monitoring.

Open access

Niyazi Acer, Mehmet Sait Dundar and Serap Bastepe-Gray

Abstract

The brain consist of about 75 percent water. Diffusion tensor imaging (DTI) is an advanced magnetic resonance (MR) technique imaging that has been developed for diagnostic and research in medicine. It can be use DTI tractography to better understand degenerating axons of white matter lesions in some neurological diseases such as MS, AD, trauma, cerebral ischemia, epilepsy, brain tumors and metabolic disorders.

Open access

Matei Sorin, Matei Gabi-Mirela and Dumitrașcu Monica

Abstract

Soils from rural zones with high natural value (HNV) agriculture systems are an important source of beneficial microbial species that can be useful for various biotechnological purposes, such as transfer of suppressiveness against plant pathogens from suppressive to disease-inducing soils by using inoculation with antagonistic selected strains. The main goal of the paper was to present the results of the research carried out on strains isolated from soil microbial populations in HNV agriculture system (Mureș county, Romania) responsible for specific suppressiveness against soil-borne phytopathogens. The dual culture method was used for assessing the mechanisms involved in antagonism against a plant pathogenic strain from genus Fusarium. The global microbial activity measured as soil respiration was intense. Total counts of bacteria and fungi estimated by dilution plate were also high. The community of heterotrophic aerobic bacteria included 13 species. Associations of fluorescent pseudomonads and actinomycetes were dominant and presented antagonistic activity against Fusarium. Twenty fungal species presented cellulolytic capability evidenced by growth on culture media with cellulose as sole source of carbon. Over cellulolytic capacity, the selected isolate of Trichoderma viride presented antagonistic activity against pathogenic Fusarium strain. Both biochemical mechanism and hyperparasitism were evidenced as involved in its antifungal activity.

Open access

Vincenza Precone, Munis Dundar, Tommaso Beccari, Eda Tahir Turanli, Stefano Cecchin, Giuseppe Marceddu, Elena Manara and Matteo Bertelli

Abstract

Analytical laboratory results greatly influence medical diagnosis, about 70% of medical decisions are based on laboratory results. Quality assurance and quality control are designed to detect and correct errors in a laboratory’s analytical process to ensure both the reliability and accuracy of test results. Unreliable performance can result in misdiagnosis and delayed treatment. Furthermore, improved quality guarantees increased productivity at a lower cost. Quality assurance programmes include internal quality control, external quality assessment, proficiency surveillance and standardization. It is necessary to try to ensure compliance with the requirements of the standards at all levels of the process. The sources of these standards are the International Standards Organization (ISO), national standards bodies, guidelines from professional organisations, accreditation bodies and governmental regulations. Laboratory networks increase the performance of laboratories in support of diagnostic screening programme. It is essential that genetic laboratories of a network have procedures underpinned by a robust quality assurance system to minimize errors and to reassure the clinicians and the patients that international standards are being met. This article provides an overview of the bases of quality assurance and its importance in genetic tests and it reports the EBTNA quality assurance system which is a clear and simple system available for access to adequate standardization of a genetic laboratory’s network.

Open access

Gabi-Mirela Matei, Sorin Matei, Elena Maria Drăghici and Marian Stoian

Abstract

The presence of oil hydrocarbons and salts in soils has as consequence the poor growth of plants due to the low availability of nutrients caused by unappropriate water regime, increased soil toxicity and the deterioration of soil structure. The present research has as main purpose the improvement of the bean plants (cultivar UNIDOR) growth and to stimulate microbial activity in rhizosphere using various natural stimulators and fertilizers (AMALGEROL,VERMIPLANT, POCO, IGUANA and FORMULEX) in greenhouse experiments on oil-polluted soil from Icoana farm, Olt county. The total counts of microorganisms (heterotrophic aerobic bacteria and filamentous fungi) were estimated by dilution plate method. The global microbial activity was measured as soil respiration by substrate-induced respiration method. Total bean plants biomass accumulation significantly increased under the influence of natural stimulators and fertilizers added (excepting IGUANA) when compared to untreated control. The best results were recorded for VERMIPLANT. Natural products induced activation of physiological activities of soil microbiota reflected in increased values of CO2 released by respiration, lower levels of colonization with phytopathogenic species, the domination of fluorescent pseudomonads, actinomycetes and cellulolytic fungi, too. The particular aspect of paper circular chromatograms reflected qualitative differences between rhizosphere soils determined by the effect of treatments with natural stimulators and fertilizers.

Open access

Samuel O. Onoja, Osborn Chinagorom, Chinyere B. C. Ikpa, Kelechi G. Madubuike, Ihechiluru I. Ezeigbo, Solomon N. Ijioma, Aruh O. Anaga and Maxwell I. Ezeja

Abstract

Gastric ulcer is one of the common cause of hospital consultation with an increasing prevalence worldwide and it is traditionally managed with herbal medicine in the developing countries. This study investigated the gastroprotective effects of methanol extract of Eremomastax speciosa leaf in rats. Cold maceration in 80% methanol was adopted during extract preparation while gas chromatography mass spectroscopy (GC-MS) was employed in the phytochemical analysis. The doses of 25, 50 and 100 mg/kg E. speciosa were used on ethanol-and indomethacin-induced gastric ulcer models in rats. The shay rat method was used to determine the effects of ESE on gastric acidity while the anticholinergic and antihistaminic activities were investigated on isolated rabbit jejunum ex vivo. The GC-MS analysis identified six bioactive compounds. Both ESE and cimetidine significantly (p < 0.05) reduced the severity of indomethacin- and ethanol-induced gastric injuries and gastric acid contents in Shay rats. The extract elicited concentration-dependent relaxation of isolated rabbit jejunum and reduced the contraction induced by both acetylcholine and histamine in the same tissue. The findings showed that ESE protected the rats against chemical-induced gastric ulcer through anticholinergic and antihistaminic mechanisms.