432 research outputs found
Investigating the Affected Factors on the Design of Display Case for Paper Work
Museum display cases are usually one of the most expensive parts in museum interior design and furniture; museum display cases are very special and have a lot of limitations in the selection of used materials. Usually, even the micrometer environment in museum shelves and display cases should be valuable in the primary control of a collection (1). The protected manuscripts in museums are particularly vulnerable in terms of vulnerability and difficulty in maintaining. The mechanisms of damage and preventive protection of these works and their changes over time depend entirely on environmental conditions (2). Display cases, as a means of protection, protect the works by increasing the security of the objects and confining them in an appropriate, stable and secure environment (3 and 4). In general, four main groups of factors cause damage to the manuscripts: 1- Physical factors 2- Chemical factors 3- Biological factors 4- Unexpected factors (5), each of which imposes specific requirements in the design and manufacture of display cases for protection. Due to the specific circumstances of these works, these requirements need to be collected and formulated in a purposeful way for the design of the display cases. This article has attempted to clarify what features each display case must have in order to be stable and to protect a manuscript by reviewing specialized texts, authoritative articles, and library resources. Finally, an example of an appropriate design based on the stated conditions is examined
Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff fluid
We consider the gravitational collapse of a spherically symmetric homogeneous
matter distribution consisting of a Weyssenhoff fluid in the presence of a
negative cosmological constant. Our aim is to investigate the effects of
torsion and spin averaged terms on the final outcome of the collapse. For a
specific interior spacetime setup, namely the homogeneous and isotropic FLRW
metric, we obtain two classes of solutions to the field equations where
depending on the relation between spin source parameters, the collapse
procedure culminates in a spacetime singularity or it is replaced by a
non-singular bounce. We show that, under certain conditions, for a specific
subset of the former solutions, the formation of trapped surfaces is prevented
and thus the resulted singularity could be naked. The curvature singularity
that forms could be gravitationally strong in the sense of Tipler. Our
numerical analysis for the latter solutions shows that the collapsing dynamical
process experiences four phases, so that two of which occur at the pre-bounce
and the other two at post-bounce regimes. We further observe that there can be
found a minimum radius for the apparent horizon curve, such that the main
outcome of which is that there exists an upper bound for the size of the
collapsing body, below which no horizon forms throughout the whole scenario.Comment: 23 pages, 11 figure
IL-12 Family Cytokines: General Characteristics, Pathogenic Microorganisms, Receptors, and Signalling Pathways
Among a wide range of cytokines, the Interleukin 12 (IL-12) family has its unique structural, functional, and immunological characteristics that have made this family as important immunological playmakers. Because of the importance of IL-12 heterodimeric cytokines in microbial infections, autoimmune diseases, and cancers, the authors of this literature discuss about the general characteristics of IL-12 family members, the interactions between IL-12 cytokines and pathogenic microorganisms, the interleukins receptors and their strategies for selecting different signalling pathways. IL-12 and IL-23 are similar in p40 subunits and both are involved in proinflammatory responses while, IL-27 and IL-35 contribute to anti-inflammatory activities; however, IL-27 is also involved in pro-inflammatory responses. There are some similarities and dissimilarities among IL-12 family members which make them a unique bridge between innate and adaptive immune systems. The bioactivities of IL-12 family indicate a brilliant promise for their applications in different fields of medicine. The members of IL-12 family are candidate for several therapeutics including gene therapy, cancer therapy, tumour therapy, and vaccination. To have an accurate diagnostic technique and definite treatment regarding to infectious diseases, the playmakers of IL-12 family as effective criteria together with microarray technology are the best choices for current and future applications
Prevalence, antibiotic-resistance properties and enterotoxin gene profile of Bacillus cereus strains isolated from milk-based baby foods
Purpose: To investigate the prevalence, distribution of enterotoxins and antibiotic resistance of B. cereus in milk-based infant foods.Methods: Three-hundred milk-based infant foods were collected and immediately transferred to the laboratory. Samples were cultured and B. cereus isolates were also confirmed using polymerase chain reaction (PCR)-based detection of gyrB gene. B. cereus strains were subjected to disk diffusion and PCR-based detection of enterotoxigenic genes.Results: Prevalence of B. cereus in infant foods was 3 %. Contamination was in the range of 12.5 – 41.5 CFU/g. Brand D had the highest prevalence of B. cereus (6.2 %). NheA (88.8 %), nheC (55.5 %) and entFM (55.5 %) were the most commonly detected enterotoxigenic genes. Bacteria showed the highest prevalence of resistance against penicillin (100 %), tetracycline (77.7 %) and oxacillin (66.6 %). Prevalence of resistance against two antibiotics were 100 %.Conclusion: Considerable prevalence of resistant and toxigenic B. cereus and high consumption of milk-based infant foods in Iran, represent an important public health issue which should be considered for further preventive approaches.Keywords: Prevalence, Bacillus cereus, Antibiotic resistance, Enterotoxigenic genes, Milk-based infant foo
The Effect of IELTS Listening Strategy Use on the Reduction of IELTS Listening Test Anxiety and on IELTS Listening Performance
The study investigates the impact of IELTS listening strategy use on the reduction of listening test anxiety and on the listening performance of the IELTS test takers in light of the data of 80 participants on the pretest and post-test IELTS listening along with the participants' score on pre-anxiety and post anxiety scale. So, drawing on the instruments including a proficiency test, pre/post-test, anxiety questionnaire, materials for strategy instruction, the participants were randomly divided into two groups: Control Group and Experimental Group, each including 40 participants. As per the procedure, after tackling their pre-listening performance and pre-anxiety score, one group was treated with IELTS-Listening related strategies and the other group was not treated, but both were administered listening test. The results of the study indicated that those treated with IELTS strategy outperformed ( t (78) = 4.57, p = .000, r = .460 ) those receiving no listening-related strategy. Furthermore, the results of a t-test run on the post-test of the groups anxiety arrived at a statistically significant difference (t (78) = 5.77, p = .000, r = .547), representing that the control group outperformed the experimental group. Also, Pearson Correlation done for finding out a potential relationship between anxiety and listening performance indicated a negative and weak to moderate relationship ((r (78) = -.26, p = .020). The pedagogical implications of the study are in detailed argued
Prevalence of OmpK35 and OmpK36 porin expression in beta-lactamase and non-betalactamase- producing Klebsiella pneumoniae
Background: The aims of this study were to confirm the presence of OmpK35 and OmpK36 in extended-spectrum beta-lactamase-producing and nonextended-spectrum beta-lactamase-producing Klebsiella pneumoniae and to determine the relationship between porin expression and resistance to third-generation cephalosporins. Methods: Fifty-two K. pneumoniae isolates were obtained and analyzed for extended-spectrum beta-lactamase and for OmpK35 and OmpK36. Results: Twenty-two (42.3) isolates of K. pneumoniae were extended-spectrum beta-lactamase producers. The OmpK35 profile in K. pneumoniae producing extended-spectrum beta-lactamase showed the presence of porin protein in ceftazidime-sensitive K. pneumoniae (six isolates), and the OmpK36 profile in K. pneumoniae producing extended-spectrum beta-lactamase revealed isolates sensitive to cefotaxime (n = 8) and ceftriaxone (n = 6). All nonextended-spectrum beta-lactamase-producing K. pneumoniae showed the presence of OmpK35 and OmpK36 porin proteins. Conclusion: The presence of OmpK35 is mostly related to ceftazidime susceptibility and less to cefotaxime and ceftriaxone susceptibility, while OmpK36 expression is seen more often in cefotaxime-sensitive isolates. OmpK35 and OmpK36 indicate nonextended-spectrum beta-lactamase producing strains, and their presence is important when selecting an antimicrobial agent. © 2012 Shakib et al
Studying photosynthetic antenna complexes in vivo and in vitro using time-resolved fluorescence spectroscopy
In this thesis, I used time-resolved fluorescence spectroscopy to study regulation of excitation energy transfer (EET) and photoprotection in cyanobacteria and the green sulfur bacterium Chlorobaculum tepidum. Chapter 1 provides a general introduction for the rest of the thesis. Chapter 2 describes the study of EET in APC trimers, which are part of the antenna of cyanobacteria in crystal and functional forms. It is concluded that the same protein has at least two different structures in APC trimers and that the structure of APC trimers in crystal form deviates to some extent from the structure of APC in protein solution. Chapter 3 presents the study of state transitions in the cyanobacterium Synechococcus elongatus 7942. It is concluded that in state II photosystem II (PSII) is quenched and the spill-over of excitation energy from PSII to PSI is not involved in state transitions. It is also shown that in state I some of the phycobilisomes (PBSs) detach from both photosystems. Chapter 4 presents a model of photoprotection in the cyanobacterium Leptolyngbya ohadii, which is normally living in the desert. In the desiccated state, excitation energy in the PBS is severely quenched as compared to the hydrated state. It is concluded that the quenching is due to the loss of the organized structure of PC rods in the dry state. Chapter 5 present the study of EET in the green sulfur bacterium C. tepidum. It is demonstrated that the efficiency of EET does not depend significantly on the temperature and that the time scale of excitation energy trapping in the reaction centers is comparable with other much smaller photosynthetic systems such as that of cyanobacteria.</p
Simultaneous detection of Escherichia coli, Salmonella enterica, Listeria monocytegenes and Bacillus cereus by oligonucleotide microarray
Background: Traditional laboratory methods to detect pathogenic bacteria are time consuming and laborious. Therefore, it is essential to use powerful and reliable molecular methods for quick and simultaneous detection of microbial pathogens.
Objectives: The current study aimed to evaluate the capability and efficiency of 23S rDNA sequence for rapid and simultaneous detection of four important food-borne pathogens by an oligonucleotide microarray technique.
Materials and Methods: The 23S rDNA sequences of Escherichia coli, Salmonella enterica, Listeria monocytogenes and Bacillus cereus were obtained from GenBank databases and used to design the oligonucleotide probes and primers by Vector NTI software. Oligonucleotide probes were placed on a nylon membrane and hybridization was performed between probes and 23S rDNA digoxigenin-labeled polymerase chain reaction (PCR) products. Hybridization signals were visualized by NBT/BCIP color development.
Results: Positive hybridization color was produced for Escherichia coli, Salmonella enterica, Listeria monocytogenes and Bacillus cereus. The oligonucleotide microarray detected all bacterial strains in a single reaction in less than five hours. The sensitivity of the performed microarray assay was 103 cfu/mL for each species of pathogen. No cross reaction was found between the tested bacterial species.
Conclusions: The obtained results indicated that amplification of 23S rDNA gene followed by oligonucleotide microarray hybridization is a rapid and reliable method to identify and discriminate foodborne pathogens tested under the study
Prevalence and Characterization of Plasmid-mediated Quinolone Resistance Genes among Escherichia coli Strains Isolated from Different Water Sources in Alborz Province, Iran
BACKGROUND: This study was conducted to investigate the prevalence of quinolone resistance associated (qnr) antibiotic resistance among Escherichia coli strains isolated from different water sources in Alborz province, Iran.METHODS: E. coli strains were isolated and identified by standard microbiological and biochemical tests from surface water sources in Alborz province, Iran in 2013. Fluoroquinolone-resistant isolates were determined using the antimicrobial susceptibility test determined by the Kirby–Bauer assay. Total genomic and plasmid DNA were extracted by boiling method. The presence of qnr genes in all nalidixic-acid and ciprofloxacin-resistant E. coli strains was determined by Polymerase Chain Reaction (PCR). The PCR amplicons were visualized after electrophoresis stained with ethidium bromide.RESULTS: One hundred E. coli strains were isolated from the water sources examined in this study. As much as 22.7% and 7.3% of the isolates were resistant to nalidixic acid and ciprofloxacin respectively. While qnrS, qnrB and qnrA genes were detected in 28%, 9% and 1% of fluoroquinolone-resistant isolates respectively. All fluoroquinolone-susceptible isolates however did not contain any of the qnr genes.CONCLUSION: This study reflects an increasing prevalence of fluoroquinolone-resistant E. coli strains in surface water sources. Underlining the importance of surface water sources as reservoirs for dissemination of potentially pathogenic E. coli and horizontal gene transfer between other waterborne bacterial species. Other possible mechanisms of resistance should also be investigated for better characterization of quinolone-resistant E. coli isolates. Therefore, immediate measures are needed to control and treat water sources more effectively.KEYWORDS: antibiotic resistance, E. coli, qnr genes, water sources
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