365 research outputs found
Towards an Architecture of Engagement
Architecture of experience transforms the user of a building into an active participant of architecture, reawakening the user to the built environment. The prevalence of architecture as a sign for the purpose of commodification has in part led to a “state of distraction” (Benjamin) that needs to be refocused to make more valuable constructs.
To make this transformation one must become, according to Rainer Rilke, “as fully conscious as possible of our existence.” Our lives are experienced in culturally constructed space, both physical and conceptual, yet based in the extramental. It is not merely a mental projection; it is based in the objective and subjective. To design and envision space we must understand the elements, and their meanings, from which the fabric of experience is woven.
This document shows how increasing “our area of responsible choices” (Jencks 13) in architectural experience, rather than manipulation of a user, will help the architect create more meaningful compositions
Direction-Oriented Stress-Constrained Topology Optimization of Orthotropic Materials
Efficient optimization of topology and raster angle has shown unprecedented
enhancements in the mechanical properties of 3D printed materials. Topology
optimization helps reduce the waste of raw material in the fabrication of 3D
printed parts, thus decreasing production costs associated with manufacturing
lighter structures. Fiber orientation plays an important role in increasing the
stiffness of a structure. This paper develops and tests a new method for
handling stress constraints in topology and fiber orientation optimization of
3D printed orthotropic structures. The stress constraints are coupled with an
objective function that maximizes stiffness. This is accomplished by using the
modified solid isotropic material with penalization method with the method of
moving asymptotes as the mathematical optimizer. Each element has a fictitious
density and an angle as the main design variables. To reduce the number of
stress constraints and thus the computational cost, a new clustering strategy
is employed in which the highest stresses in the principal material coordinates
are grouped separately into two clusters using an adjusted -norm. A detailed
description of the formulation and sensitivity analysis is discussed. While we
present an analysis of 2D structures in the numerical examples section, the
method can also be used for 3D structures, as the formulation is generic. Our
results show that this method can produce efficient structures suitable for 3D
printing while thresholding the stresses
Effect of daptomycin and vancomycin on Staphylococcus epidermidis biofilms: An in vitro assessment using fluorescence in situ hybridization
Colonization of in-dwelling catheters by microbial biofilms is a major concern in patient health eventually leading to catheter-related blood stream infections. Biofilms are less susceptible to standard antibiotic therapies that are effective against planktonic bacteria. Standard procedure for the detection of microorganisms on the catheter tip is culture. However, viable but non-culturable cells (VBNCs) may be missed. The aim of this study was to evaluate the use of fluorescence in situ hybridization (FISH) as an indicator to visualize and quantify the effect of the antibiotics daptomycin and vancomycin on biofilms in situ. We established an in vitro catheter biofilm model of Staphylococcus epidermidis biofilms on polyurethane catheters. Biofilm activity was measured by FISH and correlated to colony forming units (CFU) data. Digital image analysis was used for quantification of total biofilm mass and the area of the FISH positive biofilm cells. FISH showed a pronounced effect of both antibiotics on the biofilms, with daptomycin having a significantly stronger effect in terms of both reduction of biofilm mass and number of FISH-positive cells. This supports the anti-biofilm capacity of daptomycin. Interestingly, neither antibiotic was able to eradicate all of the FISH-positive cells. In summary, FISH succeeded in visualization, quantification, and localization of antibiotic activity on biofilms. This technique adds a new tool to the arsenal of test systems for anti-biofilm compounds. FISH is a valuable complementary technique to CFU since it can be highly standardized and provides information on biofilm architecture and quantity and localization of survivor cells
Effect of Quorum Sensing Molecule Farnesol on Mixed Biofilms of Candida albicans and Staphylococcus aureus
This article belongs to the Special Issue Microbial Biofilms, Antimicrobials, and Virulence Determinants.The natural bioactive molecule farnesol (FAR) is widely studied mainly for its antibiofilm
and antimicrobial properties. In addition, it increases the effectiveness of some antimicrobial substances,
which makes it interesting for the development of combined therapy. In the present work,
the effect of FAR either alone or in combination with oxacillin (OXA) on mixed biofilms formed
by clinically relevant pathogens, Candida albicans and Staphylococcus aureus, was studied. S. aureus
isolates used for biofilm formation originated from blood cultures and central venous catheters (CVC)
were characterized in terms of antimicrobial resistance. The minimal biofilm inhibitory concentration
(MBIC50) for FAR of 48 h mixed biofilms formed by the C. albicans and methicillin-sensitive S. aureus
(MSSA) was determined to be 125 M, and for the mixed biofilms with methicillin-resistant S. aureus
(MRSA) was determined to be 250 M. Treatment of mixed biofilms with OXA (2 mg/mL) showed
4% inhibition; however, the combination of OXA (2 mg/mL) and FAR (300 M) resulted in 80%
inhibition of biofilms. In addition, planktonic cells of S. aureus exhibited an increased susceptibility
to OXA, cefoxitin and kanamycin in the presence of FAR (150 and 300 M). Scanning electron microscopy
(SEM) micrographs confirmed patchy biofilm and lack of candidal hyphae in the samples
treated with FAR and FAR/OXA in comparison to control and mixed biofilms treated only with
OXA. Intriguingly, in a pilot experiment using fluorescence in situ hybridization (FISH), considerable
differences in activity (as indicated by ribosome content) of staphylococcal cells were detected. While
the activity rate of the staphylococci in mixed biofilms treated with FAR was high, no FISH-positive
signal for staphylococcal cells was found in the biofilm treated with FAR/OXA.This research was funded by the Slovak Research and Development Agency under contracts of SK-PT-18-0006 as part of the Bilateral Cooperation Program (2019–2022), APVV-21-0302 and APVV-18-0075. This work was also supported by the EU Grant number 952398—CEMBO, Call: H2020-WIDESPREAD-05-2020—Twinning.info:eu-repo/semantics/publishedVersio
Effects of Diode Laser, Gaseous Ozone, and Medical Dressings on Enterococcus faecalis Biofilms in the Root Canal Ex Vivo
The objective was to compare the antibacterial effects of adjunctive
disinfection using diode laser and gaseous ozone compared to the medical
dressings calcium hydroxide (Ca(OH)2) and chlorhexidine gel (CHX-Gel) on
Enterococcus faecalis biofilms in human root canals ex vivo. Root canals of
180 human extracted teeth were infected by E. faecalis and divided into 3 main
groups (G): G1, control; G2, instrumentation and irrigation using 0.9% NaCl;
G3, instrumentation and irrigation using 1% NaOCl. In each main group, the
following treatments were applied: gaseous ozone, diode laser, and medical
dressings of Ca(OH)2 or CHX-Gel for 7 days (). Reduction of colony forming
units (CFUs) inside the root canal of planktons and frequencies of adherent
bacteria after treatment were calculated. Bacterial reduction was
significantly affected by the irrigation protocol () and the disinfection
method (), and a significant interaction between both factors could be
observed (; ANOVA). In G3 (instrumentation using 1% NaOCl), no significant
effect of disinfection methods could be demonstrated on planktonic bacteria (;
ANOVA) and frequencies of adherent bacteria (; chi-square test).
Instrumentation and irrigation using NaOCl combined with ozone or laser
application resulted in comparable bacterial reduction on E. faecalis to the
application of medical dressings
Aerococcus urinae – A potent biofilm builder in endocarditis
The diagnosis of infective endocarditis (IE) remains a challenge. One of the rare bacterial species recently associated with biofilms and negative cultures in infective endocarditis is Aerococcus urinae. Whether the low number of reported cases might be due to lack of awareness and misidentification, mainly as streptococci, is currently being discussed. To verify the relevance and biofilm potential of Aerococcus in endocarditis, we used fluorescence in situ hybridization to visualize the microorganisms within the heart valve tissue. We designed and optimized a specific FISH probe (AURI) for in situ visualization and identification of A. urinae in sections of heart valves from two IE patients whose 16S rRNA gene sequencing had deteced A. urinae. Both patients had a history of urinary tract infections. FISH visualized impressive in vivo grown biofilms in IE, thus confirming the potential of A. urinae as a biofilm pathogen. In both cases, FISH/PCR was the only method to unequivocally identify A. urinae as the only causative pathogen for IE. The specific FISH assay for A. urinae is now available for further application in research and diagnostics. A. urinae should be considered in endocarditis patients with a history of urinary tract infections. These findings support the biofilm potential of A. urinae as a virulence factor and are meant to raise the awareness of this pathogen
Multisteroid LC-MS/MS assay for glucocorticoids and androgens, and its application in Addison’s disease
Objective: Liquid chromatography–tandem mass spectrometry (LC–MS/MS) offers superior analytical specificity compared with immunoassays, but it is not available in many regions and hospitals due to expensive instrumentation and tedious sample preparation. Thus, we developed an automated, high-throughput LC–MS/MS assay for simultaneous quantification of ten endogenous and synthetic steroids targeting diseases of the hypothalamic–pituitary–adrenal axis and gonads. Methods: Deuterated internal standards were added to 85 μl serum and processed by liquid–liquid extraction. Cortisol, cortisone, prednisolone, prednisone, 11-deoxycortisol, dexamethasone, testosterone, androstenedione and progesterone were resolved by ultra-high-pressure chromatography on a reversed-phase column in 6.1 min and detected by triple-quadrupole mass spectrometry. The method was used to assess steroid profiles in women with Addison's disease (AD, n=156) and blood donors (BDs, n=102). Results: Precisions ranged from 4.5 to 10.1% relative standard deviations (RSD), accuracies from 95 to 108% and extraction recoveries from 60 to 84%. The method was practically free of matrix effects and robust to individual differences in serum composition. Most postmenopausal AD women had extremely low androstenedione concentrations, below 0.14 nmol/l, and median testosterone concentrations of 0.15 nmol/l (interquartile range 0.00–0.41), considerably lower than those of postmenopausal BDs (1.28 nmol/l (0.96–1.64) and 0.65 nmol/l (0.56–1.10) respectively). AD women in fertile years had androstenedione concentrations of 1.18 nmol/l (0.71–1.76) and testosterone concentrations of 0.44 nmol/l (0.22–0.63), approximately half of those found in BDs of corresponding age. Conclusion: This LC–MS/MS assay provides highly sensitive and specific assessments of glucocorticoids and androgens with low sample volumes and is suitable for endocrine laboratories and research. Its utility has been demonstrated in a large cohort of women with AD, and the data suggest that women with AD are particularly androgen deficient after menopause.publishedVersio
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