A new approach for the study of the morphological structure of microbal biofilms

2020 ◽  
Vol 65 (10) ◽  
pp. 649-651
Author(s):  
M. S. Stepanov ◽  
A. P. Godovalov ◽  
E. E. Kobzarenko ◽  
M. V. Fadeeva ◽  
E. A. Gyr
Keyword(s):  
Morphological Structure ◽  
Petri Dish ◽  
Morphometric Study ◽  
Dense Layer ◽  
Antimicrobial Drugs ◽  
Microbial Biofilms ◽  
Persistence Layer ◽  
The Matrix ◽  
Different Diameters ◽  
The Right

Microbial biofilms are heterogeneous, moving and constantly changing communities of microorganisms, often of various taxons. Approaches to study and assessment anti-biofilm drugs widely available today do not adequately assess their effects, while the results of studying the interaction of drugs with components of the film composition can provide them the right choice. The aim of investigation was to test a new method of morphological evaluation of biofilms. To form biofilms, we used an approach when the slide was placed at an angle of 30o-45o relatively to the Petri dish, and a suspension of test strains S. epidermidis in peptone broth was poured into the space between the Petri dish and the slide. A sterile cotton swab moistened with distilled water was placed next to the glass slide to create optimal humidity. The system was placed in a thermostat for 24 hours. The formed films were examined under a microscope using the DCM 310 video eyepiece and the Scope photo x86,3.1.312 program that allowed to conduct a complete morphometric study of the film: select layers, channels, cavities and make measurements, and then save the results on electronic media in jpg file format. Microscopy of the stained slides revealed that the biofilm has a layered structure. In each image obtained using a video eyepiece, it was possible to differentiate 4 layers. From the border of the two media to the inside: the fragmentation layer, the dense layer, the matrix substance layer, and the last one - the persistence layer. Channels of different diameters (from 10 to 24 microns) are observed across the entire thickness of the biofilm. Thus, used approach allows us to visualize and evaluate the structure of microbial biofilm, measure the thickness of layers and channel diameters. In addition, this method can be used to study the effect of antimicrobial drugs on bacterial films.

scholarly journals The activity of the disinfectant “Enzidez” against bacteria in biofilms

2021 ◽  
Vol 23 (101) ◽  
pp. 67-74
Author(s):  
V. Kozhyn ◽  
M. Kukhtyn ◽  
V. Horiuk ◽  
O. Vichko ◽  
Y. Kryzhanivsky
Keyword(s):  
Optical Density ◽  
Wide Spectrum ◽  
Petri Dish ◽  
Steel Plates ◽  
Solution Temperature ◽  
E Coli ◽  
Microbial Biofilms ◽  
The Matrix ◽  
Test Cultures

Currently, the pharmaceutical industry is constantly working on the creation of ideal disinfectants that would have a wide spectrum of antimicrobial action in minimal concentrations, did not result in the formation of stability in bacteria, were not toxic, not corrosive, not allergenic, cheap. The purpose of the work was to investigate the activity of the “Enzidesis” disidissance to influence microbial biofilms in vitro conditions for various sampling parameters. The density of microbial biofilms and the effects of disinfectants were determined on sterile stainless steel plates, which were placed in a Petri dish. For this purpose, biofilms were grown on plates, washed out biofilms from planktonic cells, acted as a disguise for a certain concentration and for a period of 5–30 minutes, fixed and painted biofilms and determined the optical density of the flushing solution from biofilms spectrometrically. It has been established that the disinfectant “Enzidesis” destroys the biofilms taken in the experiment of museum test cultures S. aureus, E. coli and P. aeruginosa. In particular, for the influence of the lowest concentration in experiment, 0.075 % optical density of washing solutions from S. aureus biofilmes decreased by 2.6 times, E. coli and P. aeruginosa biofilm in 2.9 times, respectively, comparing with biofilms after treatment with water. Under the actions of such a concentration of the “Enzidesis” means, the biofilm though significantly degraded, but they were still a medium density, more than 0.5 units. Increasing the concentration of a means of 0.075 % to 0.5 % contributed to the intensity of degradation of test-cultures, an average of 3.0 times (P < 0.05) and they became a weak density (0.24–0.20 s). Increasing the concentration of the “Enzidesis” means up to 1.0 % or more, did not significantly destroy the matrix of the biofilm of microorganisms, since the optical density of the washing solutions was as in control. In determining the influence of the temperature of the working solutions of the “Enzidosis” means on its film-building activity, it has been found that with an increase in the disinfection agent “Enzidesis” with +20 to +60 °С there is an increase in the degradation of the biofilm formed S. aureus, E. coli and P. aeruginosa. Dezilities can be effectively used in 0.5 % concentration at room temperature of solutions. When substantiating the exposure time of the “Enzidesis” exhibition time, it has been found that to remove the S. aureus, E. coli and P. aeruginosa 0.5 % means at a solution temperature of +20 ± 1 °C, it is necessary that the action time is from 15 to 30 minutes.

scholarly journals Prediction of Effective Thermal Conductivities of Four-Directional Carbon/Carbon Composites by Unit Cells with Different Sizes

2021 ◽  
Vol 11 (3) ◽  
pp. 1171
Author(s):  
Chang Xu ◽  
Zhihong Sun ◽  
Guowei Shao
Keyword(s):  
Carbon Fiber ◽  
Longitudinal Direction ◽  
Unit Cell ◽  
Carbon Composites ◽  
Temperature Boundary ◽  
The Matrix ◽  
Unit Cells ◽  
Experimental Values ◽  
Different Diameters ◽  
Thermal Conductivities

Two-unit cells developed to predict the effective thermal conductivities of four-directional carbon/carbon composites with the finite element method are proposed in this paper. The smaller-size unit cell is formulated from the larger-size unit cell by two 180° rotational transformations. The temperature boundary conditions corresponding to the two-unit cells are derived, and the validity is verified by the temperature and heat flux distributions at specific positions of the larger-size unit cell and the smaller-size unit cell. The thermal conductivities of the carbon fiber bundles and carbon fiber rods are measured firstly. Then, combined with the properties of the matrix, the effective thermal conductivities of the four-directional carbon/carbon composites are numerically predicted. The results in transverse direction predicted by the larger-size unit cell and the smaller-size unit cell are both higher than experimental values, which are 5.8 to 6.2% and 7.3 to 8.2%, respectively. In longitudinal direction, the calculated thermal conductivities of the larger-size unit cell and the smaller-size unit cell are 6.8% and 6.2% higher than the experimental results, respectively. In addition, carbon fiber rods with different diameters are set to clarify the influence on the effective thermal conductivities of the four-directional carbon/carbon composites.

scholarly journals Morphological and Morphometric Study of the Supratrochlear Foramen

2018 ◽  
Vol 35 (01) ◽  
pp. 54-57
Author(s):  
F.A. Silva ◽  
T.S. Silva ◽  
P.R.F.B. Souza ◽  
R.S. Reis ◽  
M.R.S. Ferreira ◽  
...  
Keyword(s):  
Distal Humerus ◽  
Distal Portion ◽  
Medullary Canal ◽  
Human Bone ◽  
Morphometric Study ◽  
Left Handed ◽  
Academic Center ◽  
Preoperative Procedures ◽  
The Mean ◽  
The Right

Introduction The supratrochlear foramen (SF) is located in the distal portion of the humerus, formed in between the coronoid fossa and the olecranon fossa. Is associated with a narrowing of the medullary canal in the distal humerus, in addition to being a phylogenetic characteristic, more common in ancient populations. The objective was to evaluate the incidence of the supratrochlear foramen, it's shape, dimensions and translucency of the septum. Materials and Methods A total of 141 humerus adults, 72 right and 69 left-handed individuals from the collection of the Human Bone of the Academic Center of Vitória-Brazil. The format was classified as oval, round, irregular and cribriform. The vertical (VD) and transversal (TD) diameter were measured and the translucency of the septum was observed. Results Of the 141 humerus, 19.8% (28) had SF 39.3% (11) on the right side and 60.7% (17) on the left side. The oval was the most recurrent, found in 39% of the cases and the translucency was identified in 78% (110) of the bones. The mean VD was 3.653 mm and 3.492 mm on the right and left sides, respectively. The mean of the TD was 4.853 mm on the right side and 5.427 mm on the left. The area averages were 19.633 ± 20.57 mm2 on the right side and 19.919 ± 19.24 mm2 on the left side. Conclusion The knowledge of SF favors the preoperative procedures of patients with fractures in the distal humerus, necessary for the surgeries in the region.

scholarly journals Improvement of the Impact Properties of Composite Laminates by Means of Nano-Modification of the Matrix—A Review

2018 ◽  
Vol 8 (12) ◽  
pp. 2406 ◽  
Author(s):  
Hamed Saghafi ◽  
Mohamad Fotouhi ◽  
Giangiacomo Minak
Keyword(s):  
Composite Laminates ◽  
Cost Effective ◽  
Careful Consideration ◽  
Impact Performance ◽  
Compression After Impact ◽  
The Matrix ◽  
The Right ◽  
2D And 3D ◽  
The Impact ◽  
Selection Of

This paper reviews recent works on the application of nanofibers and nanoparticle reinforcements to enhance the interlaminar fracture toughness, to reduce the impact induced damage and to improve the compression after impact performance of fiber reinforced composites with brittle thermosetting resins. The nanofibers have been mainly used as mats embedded between plies of laminated composites, whereas the nanoparticles have been used in 0D, 1D, 2D, and 3D dimensional patterns to reinforce the matrix and consequently the composite. The reinforcement mechanisms are presented, and a comparison is done between the different papers in the literature. This review shows that in order to have an efficient reinforcement effect, careful consideration is required in the manufacturing, materials selection and reinforcement content and percentage. The selection of the right parameters can provide a tough and impact resistant composite with cost effective reinforcements.

scholarly journals COMPARISON OF THE EFFECT OF ANTIBIOTICS AND BACTERIOPHAGE PHAGE SAVB14 ON BIOFILMS FORMED BY STAPHYLOCOCCUS AUREUS VARIANT BOVIS

2020 ◽  
pp. 166-174
Author(s):  
Y. V. Horiuk ◽  
M. D. Kukhtyn ◽  
V. V. Horiuk ◽  
S. P. Kernychnyi
Keyword(s):  
Phosphate Buffer ◽  
Bacterial Resistance ◽  
Antimicrobial Drugs ◽  
Microbial Cells ◽  
Microbial Biofilms ◽  
Sterile Phosphate Buffer ◽  
Fold Level ◽  
Viable Bacteria ◽  
Petri Dishes ◽  
Effective Use

During the development of mastitis in cows, the formation of a biofilm pathogen is an effective way to preserve it in the microenvironment of mammary gland. Biofilm infections are difficult to treat with antimicrobials, and bacterial resistance to antibiotics increases to 1000-fold level, compared with what is observed when grown in planktonic conditions. The aim of study – to determine and compare the effect of antimicrobial drugs and bacteriophage Phage SAvB14 in the destruction of biofilms formed by S. aureus var. bovis. Isolation and species identification of staphylococci were performed according to conventional methods using BD Baird-Parker Agar medium (HiMedia, India). Determination of ability of staphylococci to form biofilms and the number of viable bacteria was determined by the Stepanovic method. The study of sensitivity of microorganisms in biofilm form was performed on daily microbial biofilms grown in plastic Petri dishes. After 24 hours of incubation of cultures, the dishes were washed three times from planktonic (unattached) microorganisms with sterile phosphate buffer and introduced the studied antibacterial agents. After exposure, the dishes were washed three times with sterile phosphate buffer, introduced 5 cm3 of sterile 0.9% sodium chloride solution and washed the biofilm, took 1.0 cm3 of suspension, prepared a series of ten-fold dilutions, inoculated 1.0 cm3 of each dilution in Petri dishes, poured MPA and incubated at temperature of 370C for 24–48 hours to determine the number of bacteria. In determining the effect of antibiotics on bacterial biofilms, it was found that of the studied antibiotics, enrofloxacin worked best probably due to its low molecular weight and ability to penetrate the pores and channels of the biofilm to microbial cells. After the action of enrofloxacin on biofilms, staphylococcal bacteria were completely inactivated. Also, the antibiotics ceftriaxone and doxycycline were effective against bacteria in biofilms. After the action of ceftriaxone, the number of surviving bacteria was lg 1.9 ± 1.1 CFU/cm2 of biofilm area, and doxycycline lg 2.5 ± 1.2 CFU/cm2. At the same time, under the action of antibiotics penicillins, aminoglycosides and macrolides, the number of surviving microbial cells was about lg 5.3 CFU/cm2 of biofilm area. In studies on the effect of bacteriophage Phage SAvB14 on biofilms formed by S. aureus var. bovis, there was their degradation. At this, viable microbial cells from the biofilm were not isolated. In this case, we can say that the phages penetrated and reached the staphylococcal cells throughout the thickness of biofilm and bacteria were susceptible to this phage. That is, there was a passive treatment of biofilm with phages, in which lysis depended on the rate of virus uptake. Therefore, the obtained results of laboratory studies indicate the prospects of effective use of our selected specific staphylococcal bacteriophage Phage SAvB14 for the destruction of biofilm formed by S. aureus var. bovis – in mastitis of cows.

The inflammatory macrophage: a story of Jekyll and Hyde

2002 ◽  
Vol 104 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Jeremy S. DUFFIELD
Keyword(s):  
Apoptotic Cells ◽  
Tissue Healing ◽  
Immune Mediated ◽  
Selective Depletion ◽  
The Matrix ◽  
Matrix Components ◽  
The Right ◽  
Extracellular Structures ◽  
Two Populations ◽  
Inflammatory Macrophage

Recent investigations have highlighted new roles for the macrophage (Mϕ) in the biology of inflammation. Selective depletion of Mϕs from inflamed sites has confirmed their predominant role in immune-mediated damage. The components of this injury have been dissected. Mϕs mediate death of stromal, parenchymal and other immune cells by engaging the death programme, resulting in apoptosis. In addition, Mϕs induce destruction of matrix and extracellular structures both directly and indirectly by inducing stromal cells to release matrix metalloproteinases. However, there is another side to the inflammatory Mϕ. Evidence is provided that Mϕs at the same sites possess the ability to aid cell proliferation, secrete and stabilize new matrix components and induce resident cells to secrete matrix components themselves. Mϕ phagocytosis of apoptotic cells brings about a change from the cell-killing matrix-degrading cell to the matrix-generating cell-proliferating tissue-healing cell. Just as both Mϕ types are necessary at the inflamed site, the right balance of these two populations is required for healing and resolution. Evidence of excessive inflammation as a manifestation of impaired phagocytosis of apoptotic cells emphasizes that defects in the transition from one Mϕ type to another may account for the uncontrolled excessive inflammation seen in disease. Recent insights into the mechanisms by which apoptotic cells signal the change of function to the Mϕ offer the prospect of novel targets for manipulation of Mϕs in the inflamed tissue.

A Morphometric Study of the Right Atrioventricular Valve in Cadavers

2015 ◽  
Vol 4 (3) ◽  
pp. 109-115
Author(s):  
Lata Munde ◽  
◽  
P.S. Bhuiyan ◽  
Keyword(s):  
Morphometric Study ◽  
Atrioventricular Valve ◽  
The Right

The Role of Average Health Status

2016 ◽  
pp. 884-899
Author(s):  
Jordan Panayotov
Keyword(s):  
Health Status ◽  
Population Health ◽  
Gold Standard ◽  
Health Impact ◽  
Local Context ◽  
Policy Options ◽  
The Matrix ◽  
The Right ◽  
No Gold Standard ◽  
Average Health

Economic, social and environmental policies, programs and projects have impact on health. Health in All Policies (HiAP) aims to improve population health by taking into account these impacts. HiAP needs appropriate tools for assessing impacts on population health. When making choices between policy options, decision-makers rely on predictions from Health Impact Assessment. Currently there is no gold standard for establishing and assessing validity of predictions. This paper distinguishes between two levels of causal pathways regarding health impacts – specific and conditional, and proposes the Average Health Status – Health Inequalities Matrix as gold standard. The Matrix facilitates making the right choices at any level and local context, thus is useful for researchers, policy-makers and practitioners for designing, analysing and evaluating all kinds of policies. By allowing quick, reliable and inexpensive appraisal of different policy options the matrix makes feasible taking into account the impacts on population health and paves the way for institutionalizing of HiAP.

Strain History and Polar Decomposition

1996 ◽  
Author(s):  
Gerhard Oertel
Keyword(s):  
Polar Decomposition ◽  
Transformation Matrix ◽  
Strain History ◽  
Transformation Matrices ◽  
Before And After ◽  
The Matrix ◽  
Principal Stretches ◽  
Principal Directions ◽  
The Right ◽  
Asymmetric Transformation

The effect of two consecutive strains (only two states enter into the calculation of a strain, the states before and after, independently of the actual strain path) can be calculated by premultiplying the transformation matrix of the first strain (its stretch tensor) with that of the second. Unless the two strains are coaxial (their principal directions coincide), however, the resulting cumulative transformation matrix represents not only a strain but also a rigid-body rotation; in that case the matrix is asymmetric. The method of polar decomposition allows one to interpret the combined transformation as if it had come about either by a strain followed by a rotation (right polar decomposition) or by a rotation followed by a strain (left polar decomposition). Let 𝔸 and 𝔹 be two stretch tensors, or transformation matrices, representing each a strain without rotation; and let the strain 𝔹 follow the strain 𝔸. Then the combined transformation matrix 𝔽 is: . . . 𝔹𝔸 = 𝔽 = ℝ𝕌= 𝕍ℝ, (8.1) . . . where 𝔽 results from premultiplication of the earlier stretch 𝔸 with the later 𝔹, where ℝ𝕌 is the “right” and 𝕍ℝ the “left” decomposition of 𝔽, where 𝕌 and 𝕍 are two distinct stretch tensors, and where ℝ is the transformation matrix for a rotation (elements of rotation matrices are indicated by the symbol aij elsewhere in this book). 𝔽 is asymmetric and ℝ differs from the identity matrix (δij) except when 𝔸 and 𝔹 are coaxial. 𝕌 and 𝕍 have the same principal stretches and differ by orientation only. In Problems 120 to 122, false approaches in the search for an appropriate decomposition of an asymmetric transformation were recognized by yielding impossible values for a rotation. Application of eq. (8.1) makes such a trial-and-error approach unnecessary.

scholarly journals Functional Polymer Hybrid Nanocomposites Based on Polyolefins: A Review

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1475
Author(s):  
Sandra Paszkiewicz ◽  
Krzysztof Pypeć ◽  
Izabela Irska ◽  
Elzbieta Piesowicz
Keyword(s):  
Uniform Distribution ◽  
Hybrid Nanocomposites ◽  
Entire Volume ◽  
Polymer Hybrid ◽  
Engineering Plastics ◽  
The Matrix ◽  
The Right ◽  
Performance Results ◽  
Relationship Of ◽  
Structure Properties

For the last twenty years, polymer hybrid nanocomposites have enjoyed unflagging interest from numerous scientific groups and R&D departments, as they provide notable enhancement of properties, even at low nanofillers’ content. Their performance results from many factors, the most important of which is the uniform distribution in the entire volume of the matrix, that still is very challenging, but is the right choice of two types of nanoparticles that can lead to an increase of dispersion stability and even more uniform distribution of fillers. The incorporation of two types of nanofillers, especially when they differ in aspect ratio or chemical nature, allows to additively reduce the price of the final composite by replacing the more expensive filler with the cheaper one, or even synergistically improving the properties, e.g., mechanical, thermal, and barrier, etc., that can extend their usage in the industry. Despite numerous review papers on nanocomposites, there is no review on how the introduction of a hybrid system of nanofillers affects the properties of polyolefins, which are the most commonly used engineering plastics. This review deeply focuses on the structure–properties relationship of polyolefins-based hybrid nanocomposites, especially based on two types of polyethylenes (low-density polyethylenes (LDPE) and high-density polyethylenes (HDPE)) and polypropylene.

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