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Contamination by zooplankton has to a certain extent limited the large-scale cultivation and industrial exploitation of microalgae. However, systematic research on these predators in microalgal culture is still lacking. The identification of zooplanktonic contaminants derived from microalgal cultures is a basis for conducting related studies. Moreover, knowledge of the ecological distribution of such predators is crucial for avoiding or reducing the risk of biological contamination in the management of large-scale microalgal cultures. Understanding the feeding behaviors of zooplanktonic contaminants contributes to the establishment of targeted prevention strategies and control methods. Early detection is essential to allow prevention and control measures to be implemented in a timely and effective way. Reducing the susceptibility of the cultured microalgae to predators through breeding strains selection, the potential of modern molecular methods, or a synthesis of these approaches will be indispensable to the management of zooplankton contamination. Furthermore, exploring the resource utilization of predators helps to understand this issue comprehensively and to turn hazard into wealth. The genus Poterioochromonas is a typical mixotrophic flagellate and has attracted increasing attention because of the dramatic damage it can inflict on a wide range of microalgal cultures, regardless of the culture system, season, or environment. This review explores our current understanding of the predator Poterioochromonas and the areas where further research is needed, which should stimulate reflection on what we still need to know about these predators from a microalgal culture perspective and how we can utilize them.

The shear capacity was evaluated for specimens connected by beech dowels and composite dowels. The bearing capacities were calculated by the shear capacity formulas of metal dowel connectors in the GB 50005 (2017), NDS (2018), and EN 1995-1-1 (2014) standards. The results showed that, except for the specimen connected by one composite dowel calculated by the GB 50005 standard (2017), the remaining calculation differences were larger. Based on the failure mode, the force analysis of the beech dowels and the composite dowels was carried out. A calculation formula for the shear bearing capacity of the beech dowels and the composite dowels was proposed. The calculated results were in strong agreement with the test results, and the margins of difference were less than 10%. Furthermore, the formulas for two and four connectors were investigated. When the number of effective connectors was calculated by the GB 50005 standard (2017), the differences between the test values and the calculated values were less than 9.36%.

Twenty-year-old Pinus radiata trees imported from New Zealand were investigated, and a comparison was made between the outerwood (rings 16–20) and corewood (rings 4–6) in terms of mechanical properties, anatomical characteristics, microfibril angle (MFA), relative crystallinity, crystallite size and lignin content to determine the relationship between their mechanical properties and microstructures. The results demonstrated that the mechanical properties of the Pinus radiata outerwood were significantly better than those of the corewood. The outerwood had a modulus of rupture (MOR) of 106 MPa, a modulus of elasticity (MOE) of 11.4 GPa, and compressive strength parallel to the grain of 38.7 MPa, and the MOR, MOE and compressive strength parallel to the grain of the corewood were 78.9 MPa, 7.12 GPa and 29.3 MPa, respectively. The observed microstructures of the Pinus radiata outerwood and corewood were different, mainly due to differences in cell wall thickness, MFA, and relative crystallinity. The double wall thickness of the tracheid cells of the corewood and outerwood were 3.65 and 5.02 µm, respectively. The MFA data indicated that the average MFA of the outerwood was 14.0°, which was smaller than that of the corewood (22.3°). With X-ray diffraction, the relative crystallinity of the corewood was determined to be 35.7%, while that of the outerwood was 40.2%. However, the crystallite size of the outerwood cell wall shows no obvious difference from that of the corewood. Imaging FTIR spectroscopy showed a slightly higher relative content of lignin in the cell wall of the outerwood. The correlation between the microstructures and mechanical properties showed that the corewood with a thin cell wall, large MFA and low relative crystallinity had poor mechanical properties, while the outerwood with a thicker tracheid, smaller MFA and higher relative crystallinity had better mechanical properties. This means that the MFA, relative crystallinity and cell wall thickness synergically affect the mechanical properties of Pinus radiata in different radial locations.

The large-scale culture of low-cost algal biomass can be significantly affected by microbial grazing on the algae. To minimize the impact, it is necessary to manage the predators. In this study, we describe a new genus and species of vampyrellid amoeba, Kinopus chlorellivorus, which caused the loss of Chlorella sorokiniana in large-scale cultures. We assigned it to the family Leptophryidae (Vampyrellida) based on morphology and small-subunit (SSU) rRNA gene sequence comparisons. Using transmission electron microscopy, we found spherical lucent inclusions, which have not been reported for any leptophryids or other vampyrellids. The gene sequence of SSU rRNA did not match any recognized genera or species and contained four characteristic regions. K. chlorellivorus preys on algae by engulfment. Laboratory feeding experiments confirmed that its grazing rate was as high as 131 Chlorella cells day(−1) individual(−1). Results of prey-range experiments demonstrated that it could consume other chlorophyte microalgae (e.g., Scenedesmus, Coelastrella, and Haematococcus) but with a strong feeding ability on Chlorella spp., with ingestion rates ranging from 2.67 to 3.15 prey predator(−1) h(−1) and growth rates of the amoeba ranging from 0.039 to 0.045 h(−1). On the basis of its high grazing ability on Chlorella, capacity to form large populations in a short period of time, and capacity to form resistant resting stages, this contaminant has the potential to cause serious problems in large-scale Chlorella culture and should be of concern to operators of algal production facilities. IMPORTANCE The vampyrellids (Vampyrellida, Rhizaria) are a major group of predatory amoebae that have attracted significant attention because of their diversity of feeding strategies. The crucial roles they play in important processes such as suppressing soil disease and controlling aquatic algae, and as microbial contaminants in outdoor large-scale algal cultures, have also received increasing attention. In this study, a new genus and species of algivorous vampyrellid amoeba, Kinopus chlorellivorus, is described as a significant grazer responsible for losses in outdoor industrial Chlorella cultures. We found that the amoeba’s detrimental effects on Chlorella cultures may be related to its specific feeding characteristics. This study provides phenotypic and genetic information on a previously unknown vampyrellid, emphasizes the impact of contaminating vampyrellids in commercial microalgal cultures, and will contribute to the development of management strategies for predicting this kind of contaminant in large-scale microalgal cultivation.

A novel flattened bamboo-wood composite cross-laminated timber (CCLT) made from flattened bamboo and hemlock lumber was developed, and its mechanical performance was investigated and quantified in this work. The results demonstrated that the CCLT columns and control hemlock CLT counterparts had nearly equal axial compression strength, but the CCLT yielded a higher compression modulus of elasticity (MOE). Additionally, the CCLT compression behaviors were not significantly affected by the height. Compared with hemlock CLT, the CCLT exhibited a slightly higher flatwise bending MOE and strength in the major strength direction. Furthermore, the MOE and strength of the CCLT under edgewise bending were 17.3% less and 16.2% greater than those under flatwise bending, respectively. The load-carrying capacity of the CCLT was mainly governed by the interfacial failure between the bamboo and wood, in which no rolling shear failure was observed. Those features are unique for the new CCLT for engineered applications.

Commercial cultivation of eukaryotic microalgae has so far employed a unicellular form of species only (e.g., Chlorella pyrenoidosa, Dunaliella salina, and Haematococcus pluvialis). In this study, we assessed the feasibility of using the filamentous eukaryotic microalga Klebsormidium sp. LGX80 as a new cultivar for biomass and lipid production. The effects of different forms and concentrations of nitrogen on growth and lipid production of Klebsormidium sp. LGX80 were studied by using a glass column (o4.5 × 60 cm) photobioreactor under laboratory conditions. Growth and lipid production of the new strain were further evaluated in an outdoor pilot-scale tubular photobioreactor. The results showed that when supplied with urea as a source of nitrogen Klebsormidium sp. LGX80 yielded a final biomass concentration of 8.49 ± 0.10 g · L-1 in which a cellular lipid content was 59.2 ± 0.4% DW. Under such conditions, the biomass and lipid productivities were 471.7 ± 5.9 and 248.1 ± 0.0 mg · L-1 · d-1 , respectively. Fatty acid analysis revealed that the main fatty acids of Klebsormidium sp. LGX80 were palmitic acid (C16:0), linoleic acid (C18:2ω6), and linolenic acid (C18:3ω3), of which linoleic acid (C18:2ω6) accounted for up to 67.5 ± 0.1% of total fatty acids. When grown outdoors in a 13,000-L tubular photobioreactor with an initial nitrogen concentration of 3 mM urea, Klebsormidium sp. LGX80 reached the highest biomass concentration of 2.63 ± 0.09 g · L-1 with the cells containing 38.0 ± 0.5% lipids (% DW), resulting in the volumetric biomass and lipid productivities of 147.2 ± 3.6 and 37.9 ± 0.9 mg · L-1 d-1 , respectively. The results of light:dark cycle experiment showed that a durative and prolonged light irradiation hindered the biosynthesis of chlorophyll a and chlorophyll b in the cells, but promoted the carotenoid accumulation. These results suggested that Klebsormidium sp. LGX80 can be a potential oleaginous filamentous microalga for commercial production of microalgal oils.

The diatom Phaeodactylum tricornutum is considered a promising "cell factory" for high-value products fucoxanthin and EPA. But its potential has not been realized due largely to microbial contamination. In this study, seven protozoan strains were identified, of which a heterolobosean amoeba was identified as the most frequently occurring and destructive predator in P. tricornutum culture. The addition of 400 mg L

The density and modulus of elasticity (MOE) distribution can provide information on the effectiveness of parametric and non-parametric methods in calculating the characteristic value of MOE. In this study, we aim to determine the optimal distribution model of the actual measured data of the lumber. We also estimate the lumber’s MOE characteristic value and compare the difference in density and MOE between natural and planted larch. Approximately 1200 pieces of dimension lumber of 4 m × 140 mm × 40 mm in size, made from larch and planted larch, were obtained, tested, and the corresponding standard MOE value was calculated. Results revealed the 3-parameter Weibull distribution to be optimal in fitting the natural and planted larch distributions. The parametric method proved effective in calculating the characteristic value of both larch groups, with characteristic MOE values of 9.73 kN/mm2 and 8.84 kN/mm2, and characteristic density values of 530 kg/m3 and 460 kg/m3 for natural and planted larch, respectively. Moreover, the MOE and density values followed grades C40 and C35. Thus, the conclusion is that the parametric method should be used to determine these characteristic values for natural and planted larch.

Grazing behaviour between protozoa and phytoplankton exists widely in planktonic ecosystems. Poterioochromonas malhamensis is a well-known and widespread mixotrophic flagellate, which is recognized to play an important role within marine and freshwater planktonic ecosystems and regarded as the greatest contamination threat for mass algal cultures of Chlorella. In this study, a comprehensive range of factors, including morphological characters, biochemical compositions, and specific growth rate of ten species or strains of Chlorella, were evaluated for their effect on the feeding ability of P. malhamensis, which was assessed by two parameters: the clearance rate of P. malhamensis on Chlorella spp. and the specific growth rate of P. malhamensis. The results showed that the clearance rate of P. malhamensis was negatively correlated with cell wall thickness and specific growth rate of Chlorella spp., while the specific growth rate of P. malhamensis was positively correlated with carbohydrate percentage and C/N ratio and negatively correlated with protein, lipid percentage, and nitrogen mass. In conclusion, the factors influencing feeding selectivity include not only the morphological character and chemical composition of Chlorella, but also its population dynamics. Our study provides useful insights into the key factors that affect the feeding selectivity of P. malhamensis and provides basic and constructive data to help in screening for grazing-resistant microalgae.

Extant eukaryote ecology is primarily sustained by oxygenic photosynthesis, in which chlorophylls play essential roles. The exceptional photosensitivity of chlorophylls allows them to harvest solar energy for photosynthesis, but on the other hand, they also generate cytotoxic reactive oxygen species. A risk of such phototoxicity of the chlorophyll must become particularly prominent upon dynamic cellular interactions that potentially disrupt the mechanisms that are designed to quench photoexcited chlorophylls in the phototrophic cells. Extensive examination of a wide variety of phagotrophic, parasitic, and phototrophic microeukaryotes demonstrates that a catabolic process that converts chlorophylls into nonphotosensitive 13(2),17(3)-cyclopheophorbide enols (CPEs) is phylogenetically ubiquitous among extant eukaryotes. The accumulation of CPEs is identified in phagotrophic algivores belonging to virtually all major eukaryotic assemblages with the exception of Archaeplastida, in which no algivorous species have been reported. In addition, accumulation of CPEs is revealed to be common among phototrophic microeukaryotes (i.e., microalgae) along with dismantling of their secondary chloroplasts. Thus, we infer that CPE-accumulating chlorophyll catabolism (CACC) primarily evolved among algivorous microeukaryotes to detoxify chlorophylls in an early stage of their evolution. Subsequently, it also underpinned photosynthetic endosymbiosis by securing close interactions with photosynthetic machinery containing abundant chlorophylls, which led to the acquisition of secondary chloroplasts. Our results strongly suggest that CACC, which allowed the consumption of oxygenic primary producers, ultimately permitted the successful radiation of the eukaryotes throughout and after the late Proterozoic global oxygenation.

Compact tension specimens were used to determine the mode I (opening crack) fracture toughness of bamboo scrimber, a bio-based product for engineering applications. The influence of thickness and grain mode were investigated, and the extended finite element method (XFEM) was used to simulate the fracture behavior of bamboo scrimber. The results showed that all of the specimens failed in a brittle way. There were no significant differences in fracture toughness among specimens with different thicknesses; however, the grain mode did have a significant effect. The average fracture toughness KIC for T-L and R-L grain modes of bamboo scrimber were 54.32 MPa·mm1/2 and 47.91 MPa·mm1/2, respectively, where the letter “L” represents the longitudinal direction, “R” represents the stack direction, and “T” represents the flattened tangential direction. Based on the results, compact tension specimens with a thickness of 10 mm are recommended to measure the mode I fracture toughness of bamboo scrimber. Furthermore, XFEM was confirmed as a useful tool to investigate the fracture behavior of bamboo scrimber.

BACKGROUNDIn order to reveal the influence of cellular characteristics and media properties on membrane microalgal harvesting, changes in the cellular characteristics and media properties of Scenedesmus acuminatus culture contaminated by microzooplankton were characterized, and their influences on membrane harvesting were compared with the control culture. Cells and algogenic organic matter (AOM) in the contaminated and control cultures were fractionated to evaluate the membrane fouling potential. RESULTSThe contaminated culture had a 32% lower average flux than control culture. Both the fractionated cells and AOM in the contaminated culture with or without concentration adjustment had higher membrane fouling potentials. Microzooplankton contamination caused more cell aggregates and transparent exopolymer particles, which formed less permeable cake layer. Increased AOM in contaminated culture contained more carbohydrates and humic/fulvic acid-like substances, which caused a 15.5-fold higher adhesion force between AOM and the membrane surface, and thus resulted in higher flux declining rates and lower backwashing recovery rates. CONCLUSIONMicrozooplankton contamination caused the formation of cell aggregates and high concentration of AOM in S.acuminatus culture. AOM played a more important role than microalgal cells in flux declining and backwashing recovery. It is necessary to develop cultivation practice and culture pretreatment techniques to improve membrane harvesting efficiency. (c) 2019 Society of Chemical Industry

Previous studies have proved that Larix kaempferi is a good material for preparing cross-laminated timber (CLT), but under bending shear stress, CLT made by Larix kaempferi is prone to the phenomenon of bonding face cracking, which seriously affects the shear performance of CLT. To solve this problem, this paper took Larix kaempferi as raw material, conducted experiments on the surface sanding conditions, gluing pressure and adhesive types of sawing timber, and explored the influence of these three factors on the bonding quality of CLT. The microscopic characteristics of the bonding layer were further studied. The results showed that for Larix kaempferi with a density of 0.68 g/cm3 used in this experiment, a high bonding pressure is required. Among the three cold curing adhesives selected in the experiment, emulsion polymer isocyanate (EPI) adhesive needs 1.5 MPa bonding pressure to ensure the bonding quality, while for polyurethane (PUR) and phenol resorcinol formaldehyde (PRF), 1.2 MPa can meet the need of adhesive pressure. This is concerned with the permeability of different adhesives under different pressures. The microscopic results of the bonding layer show that EPI adhesives have poor permeability, so it requires high bonding pressure. The influence of sanding surface of different sand-belt on block shear strength (BSS) and wood failure percentage (WFP) is not obvious, while the durability of bonding layer is better when sanding mesh number is 100. Hence, a high pressure should be used for CLT industrial production when the laminate density is higher, especially when the adhesive has poor permeability. Reasonable sanding surface treatment can be used in laminate surface treatment to improve the durability of CLT.

The compressive strength in the major direction of cross-laminated timber CLT is the key to supporting the building load when CLT is used as load-bearing walls in high-rise wood structures. This study mainly aims to present a model for predicting the average compressive strength of CLT and promoting the utilization of CLT made out of planted larch. The densities and compressive strengths of lamina specimens and CLT samples with widths of 89 and 178 mm were evaluated, and their relationship was analyzed to build a prediction model by using Monte Carlo simulation. The results reveal that the average density of the lamina and CLT were about equal, whereas the average compressive strength of the CLT was just about 72% of that of the lamina. Width exerted no significant effect on the average compressive strength of the CLT, but homogenization caused the wider CLT to have a smaller variation than that of the lamina. The average compressive strength of the lamina could be calculated by using the average density of lamina multiply by 103.10, and the average compressive strength of the CLT could be calculated according to the compression strength of lamina in major and minor direction, therefore, a new prediction model is determined to predict the average compression strength of CLT by using the average density of lamina or CLT, the average compression strength of CLT made in this study is about 74.23 times of the average density of the lamina. The results presented in this study can be used to predict the average compressive strength of CLT by using the average density of lamina and provide a fundamental basis for supporting the utilization of CLT as load-bearing walls.

Commercial cultivation of eukaryotic microalgae has so far employed a unicellular form of species only (e.g., Chlorella pyrenoidosa, Dunaliella salina, and Haematococcus pluvialis). In this study, we assessed the feasibility of using the filamentous eukaryotic microalga Klebsormidium sp. LGX80 as a new cultivar for biomass and lipid production. The effects of different forms and concentrations of nitrogen on growth and lipid production of Klebsormidium sp. LGX80 were studied by using a glass column (ø4.5 × 60 cm) photobioreactor under laboratory conditions. Growth and lipid production of the new strain were further evaluated in an outdoor pilot-scale tubular photobioreactor. The results showed that when supplied with urea as a source of nitrogen Klebsormidium sp. LGX80 yielded a final biomass concentration of 8.49 ± 0.10 g · L

Contaminating organisms in mass cultivation present one of the major challenges that must be overcome for successful commercialization of algal biofuels. The present study identified a range of contaminating organisms in Chlorella cultures cultivated in outdoor raceway ponds at the Arizona Center for Algae Technology and Innovation (Mesa, AZ). Nineteen organisms or Operational Taxonomic Units (OTU) in the Chlorella culture were identified by a combination of microscopic observation and 18S rRNA denaturing gradient gel electrophoresis (DGGE). More detailed analyses identified these contaminating organisms as 2 fungi, 7 flagellates, 3 amoebae, 4 ciliates, 1 rotifer, and 2 large insects. Among them Poterioochromonas sp., a small flagellate, appeared to be one of the most harmful causing culture collapse. In order to control Poterioochromonas sp., various operational parameters and application strategies of ultrasonic treatment were investigated. During sixteen-day consecutive Chlorella cultivation in batch mode, the ultrasonication conditions of 6 L min−1 flow rate with the power of 495 W at 100% amplitude and a treatment frequency of once for 1 h every day, was proven to be the most effective in preventing Poterioochromonas outbreak in Chlorella culture with volume of 60 L. The above ultra-sonication method was also effective at destroying an unknown fungus, an amoeba (Acanthocystis sp.), and ciliates (a member of the family Orchitophryidae). Our findings can serve as a technical foundation for the application of ultrasonication to control some of the contaminating microorganisms in mass cultivation of microalgae including Chlorella.

Small diameter logs from juvenile trees are heavily produced during the management of artificial forests around the world. As a kind of plentiful and inexpensive natural resource, the potential was not fully explored. So far the small diameter logs are mainly used as raw materials for products other than building materials. To utilize these small diameter logs originating from juvenile trees as structural members into wood construction, a kind of hybrid built-up column was developed and the performance was investigated experimentally and theoretically. It was found that column had good load-carrying capacity. To apply the developed member in wood construction, the prediction method of the column was proposed. The effective slenderness ratio which took the shear deformations due to the bending of limbs and slip of nail connections between U-shaped nails and limbs into consideration was derived based on mechanics theory. The proposed prediction method was found to have good accuracy in predicting the load-carrying capacity of the hybrid built-up column. This paper can promote the structural application of the small diameter logs originating from juvenile trees.

Spirulina (Arthrospira) platensis is the most commonly produced microalgae for commercial applications, such as nutraceuticals and feed. While crop productivity of commercial Spirulina farms is often compromised by grazers and contaminating microzooplanktons, the biodiversity and identity of the most harmful microzooplanktons in Spirulina farms have not been extensively studied. As China is the number one producer of Spirulina in the world, comprehensive information on the biodiversity and identity of microzooplanktons in Spirulina farms is essential for the long-term commercial viability of these farms. Therefore, we determined the biodiversity and identity of the major microzooplanktons that are present in eight commercial Spirulina cultivation sites throughout China. Furthermore, we identified the major grazers that appear to directly affect the productivity of Spirulina cultures. Among twenty-three species that include 2 flagellates, 2 amoebae, 15 ciliates, and 4 rotifers, Brachionus plicatilis, Frontonia sp. and one unknown Heterolobosean amoeba appeared to be the most harmful to Spirulina due to their high density and ability to graze Spirulina. The similarity of the biodiversity and abundance of the microzooplankton was > 80% among two out of eight mass cultivation sites (C and D), while the remaining cultivation sites exhibited their own unique microzooplankton biodiversity characteristics. Redundancy analysis (RDA) showed that there was a positive relationship between harmful species of Brachionus plicatilis and salinity, while the other two harmful species of Heterolobosean amoeba and Frontonia sp. had a positive relationship with oxidation-reduction potential (ORP). As this is the first report to identify the major harmful microzooplankton species in commercial Spirulina farms, our study not only provides a theoretical basis for the relationship between environmental factors and biodiversity of harmful grazers but also lays a scientific foundation for developing effective monitoring and management strategies for commercial Spirulina farms.

Chlorella is a strong candidate as a potential production organism for future biofuels and other algal-derived products, but contamination by grazing protozoa is a major constraint to its commercial production on a large scale. In this study, a mixotrophic flagellate chrysophyte that targeted Chlorella in mass culture was observed in samples from outdoor massive photobioreactor systems. Data from field studies demonstrated that once the predatory flagellate was observed in the algal culture, there was a dramatic reduction in Chlorella cell concentration. The grazer was identified as Poterioochromonas malhamensis, based on both morphology and molecular barcoding employing 18S rDNA gene sequences. Transmission electron microscopy revealed that P. malhamensis digested the ingested Chlorella sorokiniana cells within a food vacuole, with residual cell wall from the prey being observed in the final phase. It was noted that during the process of ingesting and digesting the C. sorokiniana cells, the chloroplast of P. malhamensis reduced in size, whereas the number and volume of mitochondria increased. After the prey had been completely digested, the chloroplast and mitochondria of P. malhamensis returned to their pre-feeding status. Feeding experiments in the laboratory demonstrated that cell concentrations of C. sorokiniana and P. malhamensis were negatively correlated. Furthermore, once P. malhamensis reached 5 × 105 cells mL− 1 and the ratio of C. sorokiniana to P. malhamensis was in the range 15:1 to 30:1, the cell concentration of the C. sorokiniana culture decreased dramatically. The optimal temperature for P. malhamensis grazing on C. sorokiniana was 25 °C; the grazing ability of P. malhamensis in light conditions was higher than that in dark conditions; and P. malhamensis preferred weakly acidic conditions. In addition, it was demonstrated that this flagellate could graze on other common microalgae of commercial value. On the basis of its capacity to ingest a wide spectrum of phytoplankton, and its wide environmental range and global distribution, this contaminant has the potential to be a common problem in microalgal mass cultures and warrants further study.

As the population continues to grow in China’s urban settings, the building sector contributes to increasing levels of greenhouse gas (GHG) emissions. Concrete and steel are the two most common construction materials used in China and account for 60% of the carbon emissions among all building components. Mass timber is recognized as an alternative building material to concrete and steel, characterized by better environmental performance and unique structural features. Nonetheless, research associated with mass timber buildings is still lacking in China. Quantifying the emission mitigation potentials of using mass timber in new buildings can help accelerate associated policy development and provide valuable references for developing more sustainable constructions in China. This study used a life cycle assessment (LCA) approach to compare the environmental impacts of a baseline concrete building and a functionally equivalent timber building that uses cross-laminated timber as the primary material. A cradle-to-gate LCA model was developed based on onsite interviews and surveys collected in China, existing publications, and geography-specific life cycle inventory data. The results show that the timber building achieved a 25% reduction in global warming potential compared to its concrete counterpart. The environmental performance of timber buildings can be further improved through local sourcing, enhanced logistics, and manufacturing optimizations.

The potential of using Chlorella for biomass production for biofuels and other products on a large scale has been explored for many years. However, Chlorella cells are vulnerable to predation by protozoa, resulting in productivity loss. Poterioochromonas malhamensis, a mixotrophic predator flagellate, is regarded as one of the most dangerous grazers in Chlorella cultures on a commercial scale, as it can cause deterioration or collapse of microalgal mass cultivation in just a few days. There is a need, therefore, for effective and safe methods for protecting microalgal crops from grazing organisms. In this study, a chemical compound, ammonium bicarbonate (NH4HCO3), was used to control P. malhamensis in cultures of Chlorella sorokiniana under both laboratory and pilot-scale conditions. The results showed that 400 to 800 mg L−1 NH4HCO3 could effectively control P. malhamensis, and the 24-h mortality of P. malhamensis was as high as 94% in indoor experiments and 90% in outdoor ponds. Compared with the control groups, the biomass of Chlorella increased by 77% in indoor cultures and 95% in outdoor ponds when treated with NH4HCO3. In addition, microscopic observation indicated that NH4HCO3 could also effectively control other contaminants in outdoor cultures, such as some ciliates, amoebae and cysts. Molecular sequencing further revealed that NH4HCO3 might be effective in controlling other flagellates. Experiments assessing the influence of pH on toxicity of NH4HCO3 to P. malhamensis revealed, for the first time, that it was the NH3 of NH4HCO3, not the NH4+, or the total NH3-N (NH3 and NH4+), that killed P. malhamensis. Owing to its high toxicity to P. malhamensis and other contaminants, its relative safety to C. sorokiniana, and its low commercial price and ecological acceptability, addition of NH4HCO3 is considered to be a highly effective, safe, and cost-efficient way to control P. malhamensis contamination in mass cultivation of Chlorella.

Eukaryotic microalgae and prokaryotic cyanobacteria are globally the most important primary producers, forming the base of food web in aquatic ecosystems. As such, they are eaten by a huge diversity of protistan taxa (e.g., amoeba, flagellates and ciliates), as well as zooplanktonic and larger metazoan grazers. As in terrestrial agriculture, grazing has the potential to devastate the microalgal “crop” and this has obvious implications to the commercial success of the developing microalgal industry. Whilst in conventional agriculture thousands of years of exploitation of a relatively small number of crop plants, has resulted in tools, knowledge and strategies that can manage this issue, in the case of microalgal mass culture this is relatively undeveloped. This review explores our current understanding of the issue and where further research is needed, focusing on the diversity of grazers and how microalgae under various environmental regimes and culture conditions avoid being annihilated. In addition, the implications of algal mass culture, where the objective is to maintain a virtual monoculture, are discussed in the context of how infection could be prevented/minimised and if infection occurs, how this may be managed to prevent excessive losses in productivity or quality of the algal crop. The ultimate objective would be the development of robust methodologies for the early detection of “infection” of microalgal mass-cultures. This would allow the timely implementation of best management practices to prevent/reduce, damage caused by grazing. In reality, whilst there will be areas of commonality, as in terrestrial agricultural crops, methods will be need to be specifically tailored for each algal taxon, cultivation system and location.

The phylum Ciliophora is one of the most broadly studied protozoan lineages. The era of molecular investigation has brought forth a major ongoing debate: is the subclass Peritrichia Stein, 1859 monophyletic? Numerous analyses mostly using the small subunit (SSU) rRNA gene have failed to recover the Mobilida and Sessilida, the two peritrich orders, as sister clades. Here we have sequenced five peritrich species - three sessilids and two mobilids. We constructed a supermatrix of 158 genes and 44,696 characters for 24 ciliate species, and as outgroup taxa, nine species from the Apicomplexa and four from the Dinophyceae. Our analyses using both maximum likelihood and Bayesian methods recover a monophyletic class Oligohymenophorea and two robust clades within it. The first clade is a monophyletic Peritrichia with the orders Sessilida and Mobilida maximally supported as sister clades. The second oligohymenophorean clade includes species of the subclasses Scuticociliatia and Hymenostomatia, which are sister clades. Our analyses resolve a long-standing debate in ciliate molecular phylogenetics and provide support for the classical view that the morphological features of the two peritrich orders Mobilida and Sessilida arose by descent from the same common ancestor and are not the result of convergence.

Ecological studies of contaminating microzooplankton in microalgal mass culture are important for large-scale cultivation risk management and remediation strategies, with the ultimate goal to ensure the sustainable high-yield production of microalgal biomass. Using multivariate statistical techniques, the characteristics and relationships with environmental variables of contaminating microzooplankton species were studied in commercial production of Spirulina platensis in outdoor raceway ponds in East and North China. A total of 16 microzooplankton species were identified from 64 large-scale raceway ponds, including three rotifers, two amoebae, and eleven ciliates. The relative abundance of individual microzooplankton species was in an order, from high to low, of ciliates > rotifers > amoebae. The ciliate Cyclidium marinum was the most frequently occurring species, mainly due to its wide tolerance of environmental conditions; and the rotifer Brachionus plicatilis was the key contaminating species, responsible for major loss of biomass productivity owing to its high level of occurrence and feed characteristics as an algivore. The high salinity habitats of the culture systems in North China featured the ciliate Frontonia didieri as an algophagous indicator species, while in East China the amoebae Nuclearia simplex and Euplaesiobystra hypersalinica were indicators for seed ponds and production ponds, respectively, attributed to the specific physicochemical conditions of the local environments. Fine tuning of salinity and pH away even temporarily from the optima of these contaminating microzooplankton species may be an easy and effective protocol for contamination control. Our investigation indicates the importance of comprehensively considering the environmental optima, tolerances and feed characteristics of contaminating species, together with continuous monitoring and ecological data analysis, for efficient management strategies geared towards the mitigation of biological contamination in microalgal mass culture.

This study was aimed at examining the mechanical performance of mortise and tenon joints reinforced with slot-in bamboo scrimber plates. 27 full-scale specimens were manufactured with engineered wood and bamboo products using computer numerically controlled (CNC) technology, then they were tested under monotonic loading. The initial stiffness and moment carrying capacity of joints with different reinforcing configurations were obtained from the established moment–rotational angle relationships. It was found that the initial stiffness of the reinforced mortise and tenon joints increased by 11.4 to 91.8% and the moment carrying capacity increased by 13.5 to 41.7%, respectively. The total width and grain orientation of the reinforcing plates had significant influence on the mechanical performance of the mortise and tenon joints. Fastening the plates to tenon with dowels was beneficial to the mechanical performance of the joints. The embedment length and adhesive type had no significant influence to the structural performance of the joints. This study demonstrated the feasibility of pre-reinforcing mortise and tenon joints in new timber construction, and could assist to promote the application of mortise and tenon joints in modern timber structures.

With the increasing popularity of cross-laminated timber (CLT) constructions around the world, there have been attempts to produce CLT using local wood species in different countries, such as Japanese larch (Larix kaempferi (Lamb.) Carr.) in China. Thus, the need to investigate the connection performance also increases to support the design and construction of CLT buildings using local wood species. In this study, the withdrawal properties of three different types of self-tapping screws (STS), with a diameter of 6 mm, 8 mm, and 11 mm, were tested with Japanese larch CLT. The results revealed that the withdrawal strength of STS increased with increasing density and effective length, but decreased with an increasing diameter. With a density increment of 0.05 g/cm3, the withdrawal strength increased by an average of 9.4%. With an effective length increment of 24 mm, the withdrawal strength increased by an average of 1.4%. An empirical regression model was adopted to predict the withdrawal strength of Japanese larch CLT based on the results, which can be used for potential engineering design of CLT connections using STS.