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Vietnam is one of the countries most severely affected by climate change and sea level rise, especially in the south. High-performance concrete appears to be a better choice for strong and durable structures. The primary objective of this research was to use locally available materials to produce HPC reaching compression strength of over 100 MPa and suitable for Vietnamese climatic conditions and environment. The materials locally available in Vietnam used in the study included: sulfate-resisting Portland cement (PCSR40), crushed granite as coarse aggregate (size 9.5÷19 mm), river sand with fineness modulus of 3.0, Sika®Viscocrete®-151 type superplasticizer, mineral materials (class F fly ash and silica fume), and potable water. All concrete mixtures were designed according to TCVN 10306-2014 standard. For compressive strength, concrete samples were tested after 3, 7, 28, 56, and 450 days, while the tests for splitting tensile and flexural strengths, water absorption and permeability were conducted after 28 days. In this experimental research, the greatest compressive strength values obtained at 450 days of age were 95.426 MPa in a mix containing 10 %SF + 20 %FA + 20 %Qp and 101.597 MPa in a mix containing 12.5 %SF + 20 %FA + 20 %Qp. The results showed that the optimum high-performance concrete mixes used for construction in aggressive corrosive environment of Southern Vietnam contain 7.5 %SF + 30 %FA, 10 %SF + 20 %FA, 10 %SF + 30 %FA, 12.5 %SF + 20 %FA, respectively. This study showed that the HPC produced with locally available materials in Vietnam can have compressive strength exceeding 110 MPa as well as other excellent mechanical properties. All of this can be achieved simply by using materials available at the local markets, provided they are carefully selected and properly mixed to optimize grain size distribution.

The article investigates the properties of recycled concrete powder obtained by mechanochemical activation of recycled screening waste with organic plasticizer in vibrating mill. The waste concrete powder was considered as a part of blended binder based on Portland cement. The optimal powder ratio in blended binder was 30% by weight of cement with the maintenance of the strength properties. The laser diffraction method, X-ray analysis and IR spectroscopy, as well as standard methods were used to estimate the properties of activated powder. The activation of recycled screening waste in 150 min with 0.5% plasticizer allowed us to achieve the specific surface area of the powder at the range of 457.5 cm2/g with content of fine-grained particles in the size of 0–10 µm (26.6%) and 0–20 µm (31.2%). It was estimated that the increase of powder ratio in blended binder reduces the standard consistency of the paste and extends the setting time of the binder. The optimal content of the powder was 30% by weight of cement with standard consistency of 24.6%. The compressive strength at the age of 2, 7 and 28 days was 24.3, 37.4 and 50.5 MPa respectively. The structure change of recycled screening waste particles by mechanical destruction and surface amorphization of initial crystalline phases was confirmed by XRD method and IR spectroscopy.

Disposal of tyre waste is a major environmental problem in all over of the world. It has been estimated that more than 1.5 billion tyres are produced annually and almost one million end their service life. More than 50% of them are accumulated on landfills. The tyre fiber can be added to the concrete mixture to improve not only the strength properties, but also the crack resistance of the composition. The use of recycled tire polymer fibers as reinforcement component is a perspective view on the development of dispersed concrete technology. In this research the main characteristics of the fiber and the technological characteristics of the concrete mixture are presented. The effect of the polymer fiber on strength and performance properties of sand concrete are shown. It was found that the optimal dosage of fiber is 1 kg/m3, the adding of the fiber reduces at the range 3.6% of slump of the concrete mixture. It was found that each 10 kg/m3 of recycled polymer fiber reduce the density of samples by 4%. The addition of such amount of the polymer fiber reduces the compressive strength. The addition of 1 kg/m3 has the significant effect on the reduction of the compressive and flexural concrete strength with class B15, while the same characteristics of concrete with class B30 are higher. The results of this research allow to conclude that such fiber is suitable to use in concrete with class В30 and lower.

Chemical admixtures are widely used in cement-based mixtures to reduce water demand, increase working time or accelerate strength development. The application of water-soluble polymers in building industry is increasing. The performance of cement mortars and concretes can be improved by the modification of their structure with additives of polymers. The use of polymers in cement-based compositions can decrease the intensity of hydration kinetic and increase the shrinkage deformation. Hardening of polymer-modified cement-based mixtures is associated with drying shrinkage which can significantly decrease crack resistance of cement concretes, especially in the case of polymer dispersions. The influence of polymer admixture with expansive additive on formation of cement-based pastes was investigated. Structure formation of fresh polymer modified cementitious mixtures with expansive additive was experimentally investigated by heat evolution behavior. Structure formation as a function of time and depends from initial mixture design properties such as water-cement ratio, polymer-cement ratio and content of expansive additive.

The usage of industrial and agricultural wastes for building materials production plays an important role to improve the environment and economy by preserving nature materials and land resources, reducing land, water and air pollution as well as organizing and storing waste costs. This study mainly focuses on mathematical modeling dependence of the compressive strength of high performance concrete (HPC) at the ages of 3, 7 and 28 days on the amount of rice husk ash (RHA) and fly ash (FA), which are added to the concrete mixtures by using the Central composite rotatable design. The result of this study provides the second-order regression equation of objective function, the images of the surface expression and the corresponding contours of the objective function of the regression equation, as the optimal points of HPC compressive strength. These objective functions, which are the compressive strength values of HPC at the ages of 3, 7 and 28 days, depend on two input variables as: x1 (amount of RHA) and x2 (amount of FA). The Maple 13 program, solving the second-order regression equation, determines the optimum composition of the concrete mixture for obtaining high performance concrete and calculates the maximum value of the HPC compressive strength at the ages of 28 days. The results containMaxR28HPC = 76.716 MPa when RHA = 0.1251 and FA = 0.3119 by mass of Portland cement.

The main application of concrete waste is its use as a coarse aggregate in concretes. Recycled concrete fines can be also used in concrete mixtures as fine aggregates or fillers. The paper describes an efficient activation method of recycled concrete fines to obtain technological, economical and ecological benefits. The idea is to combine mechanical and chemical methods of activation. According to various experiments the addition of superplasticizer into the mill speeds up grinding process. The present investigation shows that adding 0.5% by mass of recycled concrete fines allows obtaining higher specific area at the same processing time. Use of the prepared filler in SCC increases compressive strength more than 10% in compare with SCC containing limestone powder and mechanically activated recycled concrete fines.

Self-compacting concrete is a very perspective building material. It provides great benefits during the construction of heavily reinforced buildings. SCC has outstanding properties such as high flowability, dense structure and high strength due to specific quality of aggregates, fillers, their proportion in mix, use of polycarboxylate-based superplasticizers. Main disadvantages of SCC are high price and the difficulty of obtaining a proper mix. Use of fillers, such as fly ash type F, is a way to make SCC cheaper by replacing part of cement. Fly ash also provides some technological and operating advantages. In this paper the influence of high volume (60% from cement) fly ash type F on the properties of concrete mixture and hardened concrete is investigated. The result of the work shows the possibility of reduction the cost of SCC using ordinary fillers and high amount of fly ash. The investigated SCC has low speed of hardening (7-day compressive strength at the range of 41.8 MPa) and high volume of entrained air content (3.5%).

Abstract Background In Guinea-Bissau HIV-1, HIV-2, and HTLV-I are prevalent in the general population. The natural history of HIV/HTLV-I single and dual infections has not been fully elucidated in this population. Previous studies have shown that combinations of these infections are more common in older women than in men. The present study compares mortality associated with HIV-1, HIV-2, and HTLV-I single and dual infections in individuals over 35 years of age within an urban community-based cohort in Guinea-Bissau. Results A total of 2,839 and 1,075 individuals were included in the HIV and HTLV-I mortality analyses respectively. Compared with HIV-negative individuals, adjusted mortality rate ratios (MRRs) were 4.9 (95% confidence interval (CI): 2.3, 10.4) for HIV-1, 1.8 (95%CI: 1.5, 2.3) for HIV-2, and 5.9 (2.4, 14.3) for HIV-1/HIV-2 dual infections. MRR for HTLV-I-positive compared with HTLV-I-negative individuals was 1.7 (1.1, 2.7). Excluding all HIV-positive individuals from the analysis, the HTLV-I MRR was 2.3 (1.3, 3.8). The MRR of HTLV-I/HIV-2 dually infected individuals was 1.7 (0.7, 4.3), compared with HIV/HTLV-I-negative individuals. No statistically significant differences were found in retrovirus-associated mortality between men and women. Conclusion HIV-1-associated excess mortality was low compared with community studies from other parts of Africa, presumably because this population was older and the introduction of HIV-1 into the community recent. HIV-2 and HTLV-I-associated mortality was 2-fold higher than the mortality in uninfected individuals. We found no significant differences between the mortality risk for HIV-2 and HTLV-I single infection, respectively, and HIV-2/HTLV-I dual infection. The higher prevalence of retroviral dual infections in older women is not explained by differential retrovirus-associated mortality for men and women.

The enzymes of microorganisms that live in cold environments must be able to function at ambient temperatures. Cold-adapted enzymes generally have less ordered structures that convey a higher catalytic rate, but at the cost of lower thermodynamic stability. In this study, we characterized P355, a novel intracellular subtilisin protease (ISP) derived from the genome of Planococcus halocryophilus Or1, which is a bacterium metabolically active down to -25°C. P355's stability and activity at varying pH values, temperatures, and salt concentrations, as well as its temperature-dependent kinetics, were determined and compared to an uncharacterized thermophilic ISP (T0099) from Parageobacillus thermoglucosidasius , a previously characterized ISP (T0034) from Planococcus sp. AW02J18, and Subtilisin Carlsberg (SC). The results showed that P355 was the most heat-labile of these enzymes, closely followed by T0034. P355 and T0034 exhibited catalytic constants ( k cat ) that were much higher than those of T0099 and SC. Thus, both P355 and T0034 demonstrate the characteristics of the stability-activity trade-off that has been widely observed in cold-adapted proteases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Rasmussen, Scavenius, Thøgersen, Harwood, Larsen, Bjerga, Stougaard, Enghild and Thøgersen.)

Little is known about glandular proteins secreted from the skin- and blood-feeding ectoparasite salmon louse (Lepeophtheirus salmonis). The labial gland has ducts extending into the oral cavity of the lice, and the present study aimed to identify novel genes expressed by this gland type and to investigate their role in modulation of host parameters at the lice feeding site. Five genes associated with labial gland function were identified and named Lepeophteirus salmonis labial gland protein (LsLGP) 1-4 and 1 like (LsLGP1L). All LsLGPs were predicted to be small charged secreted proteins not encoding any known protein domains. Functional studies revealed that LsLGP1 and/or LsLGP1L regulated the expression of other labial gland genes. Immune dampening functions were indicated for LsLGP2 and 3. Whereas LsLGP2 was expressed throughout the parasitic life cycle and found to dampen inflammatory cytokines, LsLGP3 displayed an increased expression in mobile stages and appeared to dampen adaptive immune responses. Expression of LsLGP4 coincided with moulting to the mobile pre-adult I stage where hematophagous feeding is initiated, and synthetic LsLGP4 decreased the clotting time of Atlantic salmon plasma. Results from the present study confirm that the salmon louse secretes immune modulating and anti-coagulative proteins with a potential application in new immune based anti-salmon louse treatments., (© 2022. The Author(s).)

Many microorganisms feed on the tissue and recalcitrant bone materials from dead animals, however little is known about the collaborative effort and characteristics of their enzymes. In this study, microbial metagenomes from symbionts of the marine bone-dwelling worm Osedax mucofloris , and from microbial biofilms growing on experimentally deployed bone surfaces were screened for specialized bone-degrading enzymes. A total of 2,043 taxonomically (closest match within 40 phyla) and functionally (1 proteolytic and 9 glycohydrolytic activities) diverse and non-redundant sequences (median pairwise identity of 23.6%) encoding such enzymes were retrieved. The taxonomic assignation and the median identity of 72.2% to homologous proteins reflect microbial and functional novelty associated to a specialized bone-degrading marine community. Binning suggests that only one generalist hosting all ten targeted activities, working in synergy with multiple specialists hosting a few or individual activities. Collagenases were the most abundant enzyme class, representing 48% of the total hits. A total of 47 diverse enzymes, representing 8 hydrolytic activities, were produced in Escherichia coli , whereof 13 were soluble and active. The biochemical analyses revealed a wide range of optimal pH (4.0-7.0), optimal temperature (5-65 °C), and of accepted substrates, specific to each microbial enzyme. This versatility may contribute to a high environmental plasticity of bone-degrading marine consortia that can be confronted to diverse habitats and bone materials. Through bone-meal degradation tests, we further demonstrated that some of these enzymes, particularly those from Flavobacteriaceae and Marinifilaceae , may be an asset for development of new value chains in the biorefinery industry., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.)

Recent years have seen a dramatic improvement in protein-design methodology. Nevertheless, most methods demand expert intervention, limiting their widespread adoption. By contrast, the PROSS algorithm for improving protein stability and heterologous expression levels has been successfully applied to a range of challenging enzymes and binding proteins. Here, we benchmark the application of PROSS as a stand-alone tool for protein scientists with no or limited experience in modeling. Twelve laboratories from the Protein Production and Purification Partnership in Europe (P4EU) challenged the PROSS algorithm with 14 unrelated protein targets without support from the PROSS developers. For each target, up to six designs were evaluated for expression levels and in some cases, for thermal stability and activity. In nine targets, designs exhibited increased heterologous expression levels either in prokaryotic and/or eukaryotic expression systems under experimental conditions that were tailored for each target protein. Furthermore, we observed increased thermal stability in nine of ten tested targets. In two prime examples, the human Stem Cell Factor (hSCF) and human Cadherin-Like Domain (CLD12) from the RET receptor, the wild type proteins were not expressible as soluble proteins in E. coli, yet the PROSS designs exhibited high expression levels in E. coli and HEK293 cells, respectively, and improved thermal stability. We conclude that PROSS may improve stability and expressibility in diverse cases, and that improvement typically requires target-specific expression conditions. This study demonstrates the strengths of community-wide efforts to probe the generality of new methods and recommends areas for future research to advance practically useful algorithms for protein science., Competing Interests: Declaration of Competing Interest AG and SJF are named inventors on patents relating to the PROSS method and various designs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Since its discovery as part of the bacterial adaptative immune system, CRISPR/Cas has emerged as the most promising tool for targeted genome editing over the past few years. Various tools for genome editing in Bacillus subtilis have recently been developed, expanding and simplifying its potential development as an industrial species. A collection of vectors compatible with high-throughput (HTP) fragment exchange (FX) cloning for heterologous expression in Escherichia coli and Bacillus was previously developed. This vector catalogue was through this work supplemented with editing plasmids for genome engineering in Bacillus by adapting two CRISPR/Cas plasmids to the cloning technology. The customized tools allow versatile editing at any chosen genomic position (single-plasmid strategy) or at a fixed genomic locus (double-plasmid strategy). The single-plasmid strategy was validated by deleting the spoIIAC gene, which has an essential role in sporulation. Using the double-plasmid strategy, we demonstrate the quick transition from plasmid-based subtilisin expression to the stable integration of the gene into the amyE locus of a seven-protease-deficient KO7 strain. The newly engineered B. subtilis strain allowed the successful production of a functional enzyme. The customized tools provide improvements to the cloning procedure, should be useful for versatile genomic engineering, and contribute to a cloning platform for a quick transition from HTP enzyme expression to production through the fermentation of industrially relevant B. subtilis and related strains. IMPORTANCE We complemented a cloning platform with new editing plasmids that allow a quick transition from high-throughput cloning and the expression of new enzymes to the stable integration of genes for the production of enzymes through B. subtilis fermentation. We present two systems for the effective assembly cloning of any genome-editing cassette that shortens the engineering procedure to obtain the final editing constructs. The utility of the customized tools is demonstrated by disrupting Bacillus ' capacity to sporulate and by introducing the stable expression of subtilisin. The tools should be useful to engineer B. subtilis strains by a variety of recombination events to ultimately improve the application range of this industry-relevant host., (Copyright © 2020 García-Moyano et al.)

Enzymatic processing of fish by-products for recovery of peptides (hydrolysates) is a promising technology to reach food grade ingredients of high nutritional quality. Despite this, their bitter taste and "fish" odor block implementation in food products and limit their economic potential. Trimethylamine (TMA) is a known contributor to malodor in fish. Current strategies to mask or remove the odor either are not effective or give rise to undesirable side effects. As an alternative approach to remediate TMA, we propose a novel enzymatic strategy to convert TMA into the odorless trimethylamine N -oxide (TMAO) using TMA monooxygenases (Tmms). We identified a diverse set of bacterial Tmms using a sequence similarity network. Purified, recombinant enzymes were assessed for their biocatalytic capacity by monitoring NADPH consumption and TMAO generation. Selected Tmms were subjected to biochemical characterization and investigated for their ability to oxidize TMA in an industry-relevant substrate. From the 45 bacterial Tmm candidates investigated, eight enzymes from four different taxa were selected for their high activity toward TMA. The three most active enzymes were shown to vary in temperature optimum, with the highest being 45°C. Enzymatic activity dropped at high temperatures, likely due to structural unfolding. The enzymes were all active from pH 6.0 to 8.5, with functional stability being lowest around the optimal pH. All three Tmms, given sufficient NADPH cofactor, were found to generate TMAO in the TMA-rich salmon protein hydrolysate. The Tmms serve as unique starting points for engineering and should be useful for guiding process development for marine biorefineries. IMPORTANCE Enzyme-based conversion of marine biomass to high-quality peptide ingredients leaves a distinct smell of "fish" caused by the presence of trimethylamine, which limits their economic potential. We suggest an enzymatic solution for converting trimethylamine to the odorless trimethylamine N -oxide as a novel strategy to improve the smell quality of marine protein hydrolysates. Following a systematic investigation of 45 putative bacterial trimethylamine monooxygenases from several phyla, we expand the repertoire of known active trimethylamine monooxygenases. As a proof-of-concept, we demonstrate that three of these enzymes oxidized trimethylamine in an industry-relevant salmon protein hydrolysate. Our results add new oxidoreductases to the industrial biocatalytic toolbox and provide a new point of departure for enzyme process developments in marine biorefineries., (Copyright © 2020 Goris et al.)

A novel cold-adapted methane-oxidizing bacterium, termed TFB, was isolated from the thermoglacial Arctic karst spring, Trollosen, located in the South Spitsbergen National Park (Norway). The source water is cold and extremely low in phosphate and nitrate. The isolate belongs to the Methylovulum genus of gammaproteobacterial methanotrophs, with the closest phylogenetic affiliation with Methylovulum miyakonense and Methylovulum psychrotolerans (96.2 and 96.1% 16S rRNA gene sequence similarities, respectively). TFB is a strict aerobe that only grows in the presence of methane or methanol. It fixes atmospheric nitrogen and contains Type I intracellular membranes. The growth temperature range was 2-22°C, with an optimum at 13-18°C. The functional genes pmoA, mxaF, and nifH were identified by PCR, whereas mmoX and cbbL were not. C16:1ω5c was identified as the major fatty acid constituent, at an amount (>49%) not previously found in any methanotrophs, and is likely to play a major role in cold adaptation. Strain TFB may be regarded as a new psychrotolerant or psychrophilic species within the genus Methylovulum. The recovery of this cold-adapted bacterium from a neutral Arctic thermal spring increases our knowledge of the diversity and adaptation of extremophilic gammaproteobacterial methanotrophs in the candidate family "Methylomonadaceae".

Intracellular subtilisin proteases (ISPs) have important roles in protein processing during the stationary phase in bacteria. Their unregulated protein degrading activity may have adverse effects inside a cell, but little is known about their regulatory mechanism. Until now, ISPs have mostly been described from Bacillus species, with structural data from a single homolog. Here, we study a marine ISP originating from a phylogenetically distinct genus, Planococcus sp. The enzyme was successfully overexpressed in E. coli, and is active in presence of calcium, which is thought to have a role in minor, but essential, structural rearrangements needed for catalytic activity. The ISP operates at alkaline pH and at moderate temperatures, and has a corresponding melting temperature around 60 °C. The high-resolution 3-dimensional structure reported here, represents an ISP with an intact catalytic triad albeit in a configuration with an inhibitory pro-peptide bound. The pro-peptide is removed in other homologs, but the removal of the pro-peptide from the Planococcus sp. AW02J18 ISP appears to be different, and possibly involves several steps. A first processing step is described here as the removal of 2 immediate N-terminal residues. Furthermore, the pro-peptide contains a conserved LIPY/F-motif, which was found to be involved in inhibition of the catalytic activity., (© 2018 The Authors. Proteins: Structure, Function, and Bioinformatics published by Wiley Periodicals, Inc.)

The discovery of new enzymes for industrial application relies on a robust discovery pipeline. Such a pipeline should facilitate efficient molecular cloning, recombinant expression and functional screening procedures. Previously, we have developed a vector set for heterologous expression in Escherichia coli . Here, we supplement the catalogue with vectors for expression in Bacillus. The vectors are made compatible with a versatile cloning procedure based on type IIS restriction enzymes and T4 DNA ligase, and encompass an effective counter-selection procedure and complement the set of vectors with options for secreted expression. We validate the system with expression of recombinant subtilisins, which are generally challenging to express in a heterologous system. The complementarity of the E. coli and Bacillus systems allows rapid switching between the two commonly used hosts without comprehensive intermediate cloning steps. The vectors described are not limited to the expression of certain enzymes, but could also be applied for the expression of other enzymes for more generalized enzyme discovery or development.