scholarly journals Enhancement of Strength and Resistance to Sulfate Attack in Bio-Coating Material through Negative Pressure Method for Bacteria Immobilization

2021 ◽  
Vol 11 (19) ◽  
pp. 9113
Author(s):  
Keun-Hyeok Yang ◽  
Seung-Jun Kwon ◽  
Hyun-Sub Yoon
Keyword(s):  
Survival Rate ◽  
Service Life ◽  
Negative Pressure ◽  
Concrete Strength ◽  
Bacterial Count ◽  
Concrete Surface ◽  
Sulfate Attack ◽  
Sulfate Ions ◽  
Pressure Method ◽  
Bacterial Immobilization

In recent years, many studies have been performed on the crack repairing technique in concrete or the protection of the concrete surface against sulfate ions. Bacterial immobilization and survival rate are the dominant influencing factors for the repair of concrete. In this study, a negative pressure method (NPM) was developed to forcibly remove air in the porous materials of concrete, which was applied for surface repair through bio-coating using Rhodobacter capsualtus. For normal repair—repair using the conventional simple soaking method (SSM) and repair through NPM—various evaluations of the concrete strength and durability were performed. Since a reinforced concrete (RC) structure for the application of these repair methods is a sewer pipe exposed to sulfate ingress, variations in concrete mass and strength were analyzed by the accelerated sulfate resistance test. The diffusion coefficient of the sulfate ion in the repair materials and the bacterial count after the accelerating test were also measured. In order to investigate the changes in the properties of the concrete hydrates, surface analyses with SEM, XRD, and TGA were carried out on the concrete under the repair layer after the tests. In all the experimental results, the bacterial immobilization rate was evaluated, and the high immobilization rate indicates the excellent shielding of sulfate ions as well as improves the survival rate of bacteria. This not only improves the service life of the coating repair but also extends the service life of the structure itself. As a result of analyzing the composition of concrete protected by different types of repair, the results most similar to the general concrete composition without sulfate attack were obtained in the case of applying NPM, which shows the least damage from sulfate attack.

scholarly journals In vivo evaluation of a recombinant N-acylhomoserine lactonase formulated in a hydrogel using a murine model infected with MDR Pseudomonas aeruginosa clinical isolate, CCASUP2

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masarra M. Sakr ◽  
Walid F. Elkhatib ◽  
Khaled M. Aboshanab ◽  
Eman M. Mantawy ◽  
Mahmoud A. Yassien ◽  
...  
Keyword(s):  
Survival Rate ◽  
Murine Model ◽  
Histopathological Examination ◽  
Healing Process ◽  
Bacterial Count ◽  
Treated Group ◽  
Control Group ◽  
In Vivo Evaluation ◽  
Systemic Spread

AbstractFailure in the treatment of P. aeruginosa, due to its broad spectrum of resistance, has been associated with increased patient mortality. One alternative approach for infection control is quorum quenching which was found to decrease virulence of such pathogen. In this study, the efficiency of a recombinant Ahl-1 lactonase formulated as a hydrogel was investigated to control the infection of multidrug resistant (MDR) P. aeruginosa infected burn using a murine model. The recombinant N-acylhomoserine lactonase (Ahl-1) was formulated as a hydrogel. To test its ability to control the infection of MDR P. aeruginosa, a thermal injury model was used. Survival rate, and systemic spread of the infection were evaluated. Histopathological examination of the animal dorsal skin was also done for monitoring the healing and cellular changes at the site of infection. Survival rate in the treated group was 100% relative to 40% in the control group. A decrease of up to 3 logs of bacterial count in the blood samples of the treated animals relative to the control group and a decrease of up to 4 logs and 2.3 logs of bacteria in lung and liver samples, respectively were observed. Histopathological examination revealed more enhanced healing process in the treated group. Accordingly, by promoting healing of infected MDR P. aeruginosa burn and by reducing systemic spread of the infection as well as decreasing mortality rate, Ahl-1 hydrogel application is a promising strategy that can be used to combat and control P. aeruginosa burn infections.

Search for algorithms for treatment of non-specific septic spondylodiscitis

2020 ◽  
pp. 65-72
Author(s):  
V. N. Obolensky ◽  
A. V. Sytnik
Keyword(s):  
Antibiotic Therapy ◽  
Negative Pressure ◽  
Spinal Column ◽  
Treatment Results ◽  
Pressure Method ◽  
Personalized Approach ◽  
Staged Treatment ◽  
Local Antibiotic ◽  
Local Antibiotic Therapy

The treatment results of 30 patients with non-specific purulent diseases of the spine were analyzed using various methods — primary or secondary stabilization of the spinal column, local negative pressure method, prolonged local antibiotic therapy method and various implants. The results were rated as «excellent» in 16 patients, «good» in 7 people, «satisfactory» in 4 cases (relapses) and 3 patients died. The results obtained indicate the need for a personalized approach to treatment tactics, the feasibility of staged treatment and the use of additional methods.

Effect of commercial probiotic (Protexin®) on growth, survival and microbial quality of shrimp (Litopenaeus vannamei)

2017 ◽  
Vol 47 (2) ◽  
pp. 204-216 ◽  
Author(s):  
Afshin Javadi ◽  
Seyed Amin Khatibi
Keyword(s):  
Survival Rate ◽  
Growth Performance ◽  
Litopenaeus Vannamei ◽  
Control Diet ◽  
Average Daily Gain ◽  
Bacterial Count ◽  
Total Bacterial Count ◽  
Microbial Quality ◽  
Content Type

Purpose The purpose of this study was to investigate the effect of a dietary probiotic on the growth performance and survival rate of Litopenaeus vannamei shrimp. Furthermore, the microbial quality of shrimp was evaluated. Design/methodology/approach Shrimp were divided into treatment and control groups (each group containing 45 shrimp). They were fed for four weeks with a control diet alone or supplemented with a commercial probiotic (Protexin®). At the end of the trial, they were assessed for survival rate, weight gain, average daily gain and specific growth rate. Samples of tail meat were also provided aseptically from peeled shrimp for bacteriological analysis including the count of Staphylococcus aureus, enterococci, Clostridium perfringens, fecal coliform, Salmonella, Escherichia coli, Listeria monocytogenes and total bacterial count. Findings The growth performance of the probiotic-treated group significantly (p < 0.05) increased at the end of the experimental period. However, no significant differences were observed for the survival rate between the groups (p > 0.05). The count of C. perfringens and the total bacterial count in shrimp supplemented with the probiotic were significantly lower than those of controls (p < 0.05). The count of coliforms and S. aureus was not significantly different between the groups (p > 0.05). Originality/value It could be concluded that the probiotic bacteria have the potential to stimulate the growth performance of L. vannamei. They can also be used for biological control of food-borne pathogens and improve the microbial quality and safety of shrimp at the farm level.

The Reinforced Concrete Durability and Rebar Erosion Monitoring

2012 ◽  
Vol 446-449 ◽  
pp. 3252-3258
Author(s):  
Jin Yang Zhang ◽  
De Mi Cui ◽  
Lie Min Lv ◽  
Zhi Yang
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Protective Layer ◽  
Concrete Surface ◽  
Monitor System ◽  
Concrete Durability ◽  
Information Feedback ◽  
Starting Time ◽  
Cast Concrete

On the basis of the advantages of low construction cost, remarkable dynamics property, easy cast moulding and more controllable construction, the reinforced concrete construct are widely applied in buildings and main structures of constructions in China. However, the reinforced concrete is found more or less aging after many years’ utilization and erosion from the environment, which will lead to a hidden risk to affect its functions. After technical development for decades, the concrete can assure its durability under normal situation, yet the function would be deteriorated due to the erosion from the complex and harsh environment to make it hardly reach its designed service life. With the assist of CorroWatch erosion monitor system, the concrete structures’ erosion can kept watched on to obtain the depassivation development and information feedback of some key data dynamically and in long term so as to foresee precisely the erosion starting time. The newly cast concrete depassivation frontline is located on concrete surface and will tend to go through the protective layer and penetrate towards rebar as time goes on. Its structure service life can be enhanced with the re-designed durability in terms of the mentioned characters and do well the erosion proof measures.

scholarly journals Method for Pulmonary Administration Using Negative Pressure Generated by Inspiration in Mice

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 200 ◽  
Author(s):  
Yuki Oiso ◽  
Tomomi Akita ◽  
Daiki Kato ◽  
Chikamasa Yamashita
Keyword(s):  
Lung Injury ◽  
Negative Pressure ◽  
Drug Distribution ◽  
Pulmonary Delivery ◽  
Chronic Obstructive ◽  
Clinical Tests ◽  
Obstructive Pulmonary Disease ◽  
Pulmonary Administration ◽  
Pressure Method ◽  
All Trans Retinoic Acid

When developing inhaled medicines for respiratory diseases, such as chronic obstructive pulmonary disease, drugs need to be administered by pulmonary delivery to animals in non-clinical tests. Common methods require application of pressure during administration, and it may cause lung injury, so we focused on the inhalation of liquid medicines by mice themselves. This study aimed to evaluate a negative pressure method of pulmonary administration in mice by self-inhalation. First, to confirm the accuracy of delivery of liquid medicines into lungs and the potential for lung injury, Institute of Cancer Research (ICR) mice received methylene blue tetrahydrate or saline by the negative pressure method. We assessed drug distribution and usefulness of this method by administering porcine pancreatic elastase and all-trans-retinoic acid (ATRA) to mice. Consequently, we confirmed good distribution of the dye and no injury such as disruption of blood flow or destruction of alveoli in lungs of mice. Following production of the murine emphysema model, the mean linear intercept (Lm) was calculated as 78 ± 4 μm. Moreover, a significant therapeutic effect of administration of the ATRA was confirmed. These results suggest that this negative pressure method of administration may be useful for pulmonary administration in non-clinical tests.

scholarly journals Deterioration Process of Concrete Exposed to Internal Sulfate Attack

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1336 ◽  
Author(s):  
Weifeng Chen ◽  
Bei Huang ◽  
Yuexue Yuan ◽  
Min Deng
Keyword(s):  
Compressive Strength ◽  
Sulfate Attack ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Great Loss ◽  
Sulfate Ions ◽  
Coarse Aggregates ◽  
Deterioration Process ◽  
One Year ◽  
Internal Sulfate Attack

Damage to concrete structures with gypsum-contaminated aggregate occurs frequently. Aggregates in much of the southern part of China are contaminated with gypsum. Therefore, in this study, the effects of using different quantities of gypsum-contaminated aggregate on the expansion and compressive strength of concrete were investigated over a period of one year. Two groups of concrete were designed with the gypsum-contaminated aggregate containing different parts of fine and coarse aggregate, respectively. The SO3 contents were 0%, 0.5%, 1%, 1.5%, 3%, 5%, and 7% by weight of aggregate. X-ray diffraction (XRD), thermogravimetry (TG), and differential scanning calorimetry (DSC) were used to analyze the change in mineral composition over time. The microstructure was also studied by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that significant expansion and great loss in compressive strength did not occur in concrete if the content of SO3 lay below 1.5% and 3% in fine and coarse aggregates, respectively. The concentration of sulfate ions in concrete was not enough to form new a phase of gypsum. During the process of internal sulfate attack, the content of gypsum decreased and the content of ettringite increased. Ettringite was the main reason for the expansion damage of concrete. Additionally, the fracture mode of internal sulfate attack on concrete was the crack extension from gypsum to paste; finally, the aggregate separated from the paste.

Effect of Erosion Damage on Diffusion of Sulfate Ions in Concrete

2011 ◽  
Vol 243-249 ◽  
pp. 4683-4686 ◽  
Author(s):  
Chao Sun ◽  
Jian Kang Chen
Keyword(s):  
Differential Equation ◽  
Diffusion Equation ◽  
Numerical Method ◽  
Nonlinear Diffusion ◽  
Damage Evolution ◽  
Sulfate Attack ◽  
Nonlinear Diffusion Equation ◽  
Second Law ◽  
Sulfate Ions ◽  
Erosion Damage

Based on Fick’s second law and the damage evolution due to sulfate attack, a new model is proposed to analyze the diffusion of sulfate ions in concrete. The relation between erosion damage and erosion time, as well as the concentration of sulfate ions is firstly investigated by virtue of the ultrasonic experimental results. Furthermore, the damage evolution is treated as the increase of porosity, and a new nonlinear differential equation on the diffusion of sulfate ions is established by substituting such an increasing porosity into Fick’s law. The nonlinear diffusion equation is then solved by numerical method. It is found that the erosion damage can significantly affect the diffusion of sulfate ions in concrete.

Study of Fine-Grained Composites Exposed to Sulfuric Acid and Sodium Sulfate

2016 ◽  
Vol 827 ◽  
pp. 275-278
Author(s):  
Martin Vyšvařil ◽  
Markéta Rovnaníková
Keyword(s):  
Waste Water ◽  
Sulfuric Acid ◽  
Sodium Sulfate ◽  
Sulfate Attack ◽  
Sewer Pipes ◽  
Sulfate Ions ◽  
Fine Grained ◽  
One Year ◽  
Corrosion Of Steel ◽  
Loss Of Strength

The degradation of concrete due to ingress of sulfate ions from the environment plays an important role in the durability of concrete constructions, especially in sewage collection systems where concrete sewer pipes are exposed to sulfates from waste water and from biogenic activity of bacteria. During this process the pH of the surface of concrete sewer pipes is reduced and it may lead to the steel depassivation and results in the corrosion of steel reinforcement. Damage due to sulfate interaction can result in the cracking and softening, with loss of strength of concrete. This paper is focused on the sulfate attack on fine-grained concrete where the effect of one-year contact of 0.5% H2SO4, and 5% Na2SO4 on changes of pH and content of sulfates in 7 types of concrete has been analyzed. It was found that after one year of sulfate attack on concrete, significant growth of content of sulfates is observed in the lowermost layer of the samples. Samples treated by 5% Na2SO4 contain slightly more sulfates in the upper layers than samples treated by sulfuric acid. The reduction in pH of aqueous leaches occurred in all layers of the samples. However, even in the lower layers of the samples, the reduction of pH below 9.5 did not turn up (except for SRS sample), and thus the conditions for the depassivation of reinforcement were not met.

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