Application of microbial biocementation to improve the physico-mechanical properties of cement mortar

AbstractCalcite is one of the most common and wide spread mineral on Earth constituting 4wt% of the Earth’s crust. It is naturally found in extensive sedimentary rock masses, as lime stone marble and calcareous sandstone in marine, fresh water and terrestrial environments. Calcium carbonate is one of the most well known mineral that bacteria deposit by the phenomenon called biocementation or microbiologically induced calcite precipitation (MICP). Such deposits have recently emerged as promising binders for protecting and consolidating various building materials. Microbially enhanced calcite precipitation on concrete or mortar has become an important area of research regarding construction materials. This study describes a method of strength and water absorption improvement of cement–sand mortar by the microbiologically induced calcium carbonate precipitation. A moderately alkalophilic aerobic Sporosarcina pasteurii was incorporated at different cell concentrations with the mixing water. The study showed that a 33% increase in 28days compressive strength of cement mortar was achieved with the addition of about one optical density (1OD) of bacterial cells with mixing water. The strength and water absorption improvement are due to the growth of calcite crystals within the pores of the cement–sand matrix as indicated from the microstructure obtained from scanning electron microscopy (SEM) examination

Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016

As mortality rates decline, life expectancy increases, and populations age, non-fatal outcomes of diseases and injuries are becoming a larger component of the global burden of disease. The Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) provides a comprehensive assessment of prevalence, incidence, and years lived with disability (YLDs) for 328 causes in 195 countries and territories from 1990 to 2016

Quality improvement and shelf-life extension of refrigerated Nile tilapia (Oreochromis niloticus) fillets using natural herbs

The present study was preformed to evaluate the effect of dip treatments by thyme (Thymus vulgaris) extract (0.5%) and rosemary (Rosmarinus officinalis) extract (1.5%) on the quality and shelf life of Nile tilapia (Orechromis niloticus) fillets during refrigerated storage at 2 ± 1 °C. The control (untreated) and treated groups were examined periodically at day zero and every 3 days (0, 3, 6, 9, 12, 15, 18, ....) during refrigeration until apparent decomposition of each group, with sensory, physicochemical and microbiological methods. The obtained results showed that thyme extract has strong antimicrobial and antioxidant activity and can maintain the quality parameters and extend the shelf life of refrigerated Nile tilapia fillets for 9 days longer than control one, while rosemary extract had efficient antioxidant activity with weak antimicrobial action

Reliability of 3-m Backward Walk Test in Patients with Primary Total Knee Arthroplasty

The 3-m backward walk test (3MBWT) is used to evaluate neuromuscular control, proprioception, protective reflexes, fall risk, and balance. The aim of the present study was to determine the test-retest reliability of the 3MBWT in patients with primary total knee arthroplasty (TKA). Twenty-eight patients with primary TKA, operated by the same surgeon, were included in this study. Patients performed trials for 3MBWT twice on the same day. Between the first and second trials, patients waited for an hour on sitting position to prevent fatigue. The 3MBWT showed an excellent test-retest reliability in this study. Intraclass correlation coefficient (ICC) for 3MBWT was 0.97. The standard error of measurement and smallest real difference at the 95% confidence level for 3MBWT were 1.06 and 2.94, respectively. The 3MBWT has an excellent test-retest reliability in patients with primary TKA. It is an effective and reliable tool for measuring dynamic balance and participant falls. As a clinical test, the 3MBWT is easy to score, requires little space, has no cost, needs no special equipment, and can be applied in a short time as part of the routine medical examination. © 2020 World Journal of Traditional Chinese Medicine | Published by Wolters Kluwer - Medknow

Antimicrobial Activity of Starch-based Biodegradable Antimicrobial Films Incorporated with Biosynthesized Silver Nanoparticles Against Multiple Drug-resistant Staphylococcus aureus Food Isolates

This study was conducted to determine the antimicrobial activity of starch-based biodegradable antimicrobial films incorporated with biosynthesized silver nanoparticles (Ag-NPs) against multiple drug-resistant Staphylococcus aureus food isolates. Herein, the in-vitro antimicrobial activities of Origanum marjorana (OM) leaf extract, OM essential oil, OM nano-emulsion, chemically synthesized Ag-NPs (chem-Ag-NPs), and OM-based biosynthesized Ag-NPs (bio-Ag-NPs) using OM extracts were determined against a cocktail of three pathogenic Staphylococcus (S.) aureus strains isolated from meat products, using the agar well diffusion assay (AWDA). Afterward, homemade starch-based biodegradable antimicrobial films (SBAF) were incorporated with the suitable antimicrobials, based on AWDA and preliminary experiments, and investigated for their antimicrobial properties against S. aureus cocktail through the disc diffusion assay (DDA). The obtained results showed that in WDA, bio-Ag-NPs (1mM) had a significantly higher antimicrobial activity than chem-Ag-NPs (1mM), with inhibition zones accounting for 23 and 19mm, respectively. Whereas both types of nanoparticles were significantly more potent in their antimicrobial properties than different concentrations of OM extract, essential oil, and nano-emulsion (p<0.05). In concern to SBAF incorporated with antimicrobials, SBAF incorporated with chem-Ag-NPs (SBAF/chem-Ag-NPs) showed a significantly stronger antimicrobial effect than SBAF incorporated with bio-Ag-NPs (SBAF/bio-Ag-NPs) in the DDA, while both types of films produced significantly larger zones of inhibition than other antimicrobials (p<0.05). These homemade biodegradable films incorporated with bio-Ag-NPs could be a good alternative to petroleum-based packaging (plastic) in food packaging applications and meanwhile improve food safety and quality. Further studies investigating the effectiveness of these films on bacterial isolates inoculated in real food samples are suggested

Utilization of microbial induced calcite precipitation for sand consolidation and mortar crack remediation

The microbes can hydrolyze urea by urease enzyme to produce ammonium as well as carbonate ions and in the presence of calcium ions which can precipitate calcium carbonate; this process is called “biocalcification” or microbial induced calcite precipitation (MICP).This technology is environmentally friendly not only because it gives strength to sand body, but also it allows water to penetrate to sand body, which is unlike silicate cement that will destroy the ecosystem of the earth. Calcium carbonate precipitated by bacteria acts as a binding material to sand particles, so incompact sand will be consolidated. Calcium chloride, calcium acetate and calcium nitrate (1 M) as calcium sources were tested for their ability to consolidate sand by mixing with urea (1 M) and bacteria cells (one optical density, 1 OD). The key point of this study aimed to choose the suitable calcium source which produces higher compressive strength and lower water absorption. The results showed that the degree of crystallinity and amount of precipitated calcium carbonate, as well as the consequent increase in strength of consolidated sand, in case of calcium chloride medium are higher than those precipitated in case of calcium acetate as well as calcium nitrate media. In addition, consolidated sand by calcium chloride was also used for cement mortar crack remediation

Scaling up for the industrial production of rifamycin B; optimization of the process conditions in bench-scale fermentor

Optimization of fermentation process conditions using a gene amplified variant of Amycolatopsis mediterranei (NCH) was carried out. The use of aeration level 1.5 vvm increased the yield by 16.6% (from 13.81 to 16.1 g/l) upon controlling the temperature at 28 °C. Adjustment of the aeration level at 1.5 vvm for 3 days then controlling the dissolved oxygen (DO) at 30% saturation further increased the yield to 17.8 g/l. The optimum pH was 6.5 for 3 days then 7 thereafter when a production yield of 16.1 g/l was recorded using an aeration rate of 1.5 vvm. Controlling the pH at constant value (6.5 or 7) all through the fermentation process decreased the yield by 5–21%. Controlling the temperature at 30 °C for 3 days then 28 °C thereafter slightly increased the yield by 5% upon using an aeration rate of 1 vvm while it decreased upon using an aeration rate of 1.5 vvm. Integration of the most optimum conditions increased the production yield by 22% from 13.81 to 17.8 g/l

Correction to : A phase I/II study of gemcitabine during radiotherapy in children with newly diagnosed diffuse intrinsic pontine glioma (Journal of Neuro-Oncology, (2017), 135, 2, (307-315), 10.1007/s11060-017-2575-9)

In Table 2 of the original publication, there were errors in the baseline scores for the PedsQL TM 3.0 Cancer Module questionnaire, so a corrected version of Table 2 is shown in this erratum. In the subcategories of the PedsQL TM 3.0 Cancer Module questionnaire, nausea and fear of procedure did not score significantly lower after treatment compared to baseline. So, based on the corrected data in Table 2, there was no significant decrease in the total score of the cancer questionnaire, and this statement in the previous manuscript was incorrect