Induced calcium carbonate precipitation using Bacillus species

Microbially induced calcium carbonate precipitation is an emerging process for the production of self-healing concrete. This study was aimed to investigate the effects and optimum conditions on calcium carbonate biosynthesis. Bacilluslicheniformis, Bacillus sphaericus, yeast extract, urea, calcium chloride and aeration were found to be the most significant factors affecting the biomineralization of calcium carbonate. It was noticed that the morphology of microbial calcium carbonate was mainly affected by the genera of bacteria (cell surface properties), the viscosity of the media and the type of electron acceptors (Ca²⁺). The maximum calcium carbonate concentration of 33.78 g/L was achieved at the optimum conditions This value is the highest concentration reported in the literature

Usporedba učinaka Presynch-Ovsynch, Presynch-Ovsynch+CIDR i G6G protokola na reproduktivne pokazatelje Holstein krava u laktaciji u razdoblju nakon teljenja

This study was performed on an industrial dairy farm near Tehran province, Iran, on 666 lactating Holstein cows from September 2019 to June 2020 in order to eliminate the harmful effects of heat stress on the reproductive performance of the cows. The hypothesis of the recent study was that by increasing the serum concentration of progesterone (P4) in the luteal phase before insemination in the form of Presynch-Ovsynch+CIDR (POC) and G6G protocols, the pregnancy rate of cows would be increased compared to the Presynch-Ovsynch (PO) protocol. The aim of the present study was to evaluate the effects of Presynch-Ovsynch (PGF2α-14d- PGF2α-12d-Ovsynch (OVS: GnRH(GnRH1)- 7d-PGF2α(PG)-2d-GnRH)-18h-Fixed-time artificial insemination (FTAI), n=212), Presynch-Ovsynch+CIDR (similar to the PO protocol, plus the use of a CIDR for 7 days, from the start of the OVS+FTAI protocol to the time of PG injection, n=230), and G6G (PGF2α- 2d-GnRH-6d-OVS+FTAI, n=224) protocols on the reproductive performance and pregnancy rate of lactating Holstein cows. The average body condition score (BCS) for the cows was about 2.5 at the time of the onset of the OVS+FTAI program. The average daily milk production for cows at the time of the start of the OVS+FTAI program was 38.3 kg/day. On average, the studied cows were inseminated 86 days postpartum. Implementation of the G6G protocol in comparison to the PO and POC protocols increased the serum concentration of P4 at GnRH1 (P=0.04). The cows that received the G6G protocol had a greater number of corpuses luteum (CL) on their ovaries at PG in comparison to the cows in the PO and POC protocols (P=0.03 and P=0.05, respectively). For all treatment protocols, the pregnancy rate of cows with >2 CLs on their ovaries at PG was significantly higher than for cows with ≤2 CLs on their ovaries at this time. The overall pregnancy rate for all cows studied was 42%. Separately, pregnancy rates for cows in PO, POC, and G6G protocols were calculated at 36.7%, 41.7%, and 47.3% respectively. The highest and the lowest pregnancy rates were obtained in the G6G and PO protocols, respectively (P=0.03). It can be concluded that the G6G protocol increased the pregnancy rate of cows in comparison to the PO but not to the POC protocol. This result can be attributed to the increase in serum concentration of P4 at GnRH1 and the greater number of CLs at PG following implementation of the G6G compared to the PO protocol. Although CIDR administration in the POC protocol led to an increase in the pregnancy rate of cows compared to the PO protocol, possibly by increasing the synchrony rate and the quality of the ovulatory follicle, this increase was not statistically significant (P=0.09).Novija studija provedena je na industrijskoj mliječnoj farmi blizu Teheran provincije u Iranu, na 666 Holstein krava u laktaciji od rujna 2019. do lipnja 2020. godine u svrhu eliminacije štetnih učinaka toplinskog stresa na reproduktivne pokazatelje krava. Pretpostavka studije koja je prethodila ovom radu bila je da će se postotak gravidnosti krava, povećanjem koncentracije progesterona (P4) u serumu u lutealnoj fazi prije oplodnje putem Presynch-Ovsynch+CIDR (POC) i G6G protokola, povećati u usporedbi s Presynch- Ovsynch (PO) protokolom. Cilj ove studije bio je procijeniti učinke Presynch-Ovsynch (PGF2α-14d-PGF2α-12d-Ovsynch (OVS: GnRH(GnRH1)-7d-PGF2α(PG)-2d-GnRH)- 18h-fiksno vrijeme umjetnog osjemenjivanja (FTAI), n=212), Presynch-Ovsynch+CIDR (slično kao PO protokol, plus uporaba CIDR tijekom 7 dana, od početka OVS+FTAI protokola do vremena ubrizgavanja PG, n=230) te G6G (PGF2α-2d-GnRH-6d- OVS+FTAI, n=224) protokola na reproduktivne pokazatelje i postotak gravidnosti Holstein krava u laktaciji. Prosječno bodovanje stanja tijela (BSC) za krave bilo je oko 2,5 u vrijeme početka OVS+FTAI programa. Prosječna dnevna proizvodnja mlijeka za krave na početku OVS+FTAI programa bila je 38,3 kg/dan. U prosjeku, istraživane krave bile su osjemenjene 86 dana nakon teljenja. Implementacija G6G protokola u usporedbi s PO i POC protokolima povećala je koncentraciju P4 u serumu pri GnRH1 (P=0,04). Krave koje su primale G6G protokol imale su veći broj žutih tijela (CL) na svojim jajnicima kod PG u usporedbi s kravama u PO i POC protokolima (P=0,03, odnosno P=0,05). Za sve protokole liječenja, postotak gravidnosti krava koje su imale >2 žuta tijela na jajnicima kod PG bio je značajno veći od krava koje su u to vrijeme imale ≤2 žuta tijela na svojim jajnicima. Sveukupni postotak gravidnosti svih proučavanih krava bio je 42 %. Zasebno, postotci gravidnosti za krave u PO, POC i G6G protokolima izračunati su kako slijedi: 36,7 %, 41,7 %, odnosno 47,3 %. Najveći i najniži postotak gravidnosti postignuti su G6G, odnosno PO protokolom (P=0,03). Može se zaključiti da je G6G protokol povećao postotak gravidnosti krava u usporedbi s PO protokolom, ali ne i POC protokolom. Ovaj rezultat moguće je pripisati povećanju P4 koncentracije u serumu pri GnRH1 i većem broju žutih tijela kod PG nakon implementacije G6G protokola u usporedbi s PO protokolom. Premda je primjena CIDR u POC protokolu dovela do povećanja postotka gravidnosti krava u usporedbi s PO protokolom, moguće povećanjem sinkronizacijske stope i kvalitete ovulacijskog folikula, to povećanje nije statistički značajno (P=0,09)

Development of an innovative urease-aided self-healing dental composite

Dental restorative materials suffer from major drawbacks, namely fracture and shrinkage, which result in failure and require restoration and replacement. There are different methods to address these issues, such as increasing the filler load or changing the resin matrix of the composite. In the present work, we introduce a new viable process to heal the generated cracks with the aid of urease enzyme. In this system, urease breaks down the salivary urea which later binds with calcium to form calcium carbonate (CaCO₃). The formation of insoluble CaCO₃ fills any resultant fracture or shrinkage from the dental composure hardening step. The healing process and the formation of CaCO₃ within dental composites were successfully confirmed by optical microscope, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDS) methods. This research demonstrates a new protocol to increase the service life of dental restoration composites in the near future

Bioconcrete: next generation of self-healing concrete

Concrete is one of the most widely used construction materials and has a high tendency to form cracks. These cracks lead to significant reduction in concrete service life and high replacement costs. Although it is not possible to prevent crack formation, various types of techniques are in place to heal the cracks. It has been shown that some of the current concrete treatment methods such as the application of chemicals and polymers are a source of health and environmental risks, and more importantly, they are effective only in the short term. Thus, treatment methods that are environmentally friendly and long-lasting are in high demand. A microbial self-healing approach is distinguished by its potential for long-lasting, rapid and active crack repair, while also being environmentally friendly. Furthermore, the microbial self-healing approach prevails the other treatment techniques due to the efficient bonding capacity and compatibility with concrete compositions. This study provides an overview of the microbial approaches to produce calcium carbonate (CaCO₃). Prospective challenges in microbial crack treatment are discussed, and recommendations are also given for areas of future research

The Effect of Cell Immobilization by Calcium Alginate on Bacterially Induced Calcium Carbonate Precipitation

Microbially induced mineral precipitation is recognized as a widespread phenomenon in nature. A diverse range of minerals including carbonate, sulphides, silicates, and phosphates can be produced through biomineralization. Calcium carbonate (CaCO₃) is one of the most common substances used in various industries and is mostly extracted by mining. In recent years, production of CaCO₃ by bacteria has drawn much attention because it is an environmentally- and health-friendly pathway. Although CaCO₃ can be produced by some genera of bacteria through autotrophic and heterotrophic pathways, the possibility of producing CaCO₃ in different environmental conditions has remained a challenge to determine. In this study, calcium alginate was proposed as a protective carrier to increase the bacterial tolerance to extreme environmental conditions. The model showed that the highest concentration of CaCO₃ is achieved when the bacterial cells are immobilized in the calcium alginate beads fabricated using 1.38% w/v Na-alginate and 0.13 M CaCl₂

History and manufacturing of glass

Glass usage in structures has increased dramatically during the last decades due to its special properties, such as transparency, high theoretical strength, low density, durability and functionality. This paper reviews glass as a material in addition to different methods of glass manufacturing (float glass and cast glass) and how they have developed over the years. In addition, this paper reviews different glass types (annealed glass, heat strengthened glass, toughened glass, and laminated glass) and their properties