Fossil fuels, including coal, oil and natural gas, remain the main source of global energy supply. Not only the storage capacity is limited, but also the use of the ecological environment causes ...great damage, a serious threat to human life safety. Microalgae biodiesel receives extensive attention due to its biodegradable and carbon-neutral green energy characteristics, which is used to reduce or replace the use of these fossil fuels. Because of the slow growth of microalgae, low lipid content and low biodiesel production, people begin to study ways to improve the growth and lipid production of microalgae and catalytic conversion of biodiesel. In this paper, the research progress of the whole process from microalgae culture to microalgae oil production to microalgae catalytic conversion of biodiesel in recent years is reviewed. The efficient growth and oil production of microalgae, the catalytic conversion methods of microalgae biodiesel and the application prospects of microalgae biodiesel are discussed and summarized. Specifically, this review critically discusses: (i) The current development status of microalgae culture and microalgae biodiesel; (ii) Cultivation methods for efficient growth and oil production of microalgae under different stress conditions; (iii) The effects of different types of catalysts and catalytic methods on the yield of biodiesel; (iv) Environmental problems and economic value of the whole process of microalgae biodiesel production; (v) Current limitations and future research directions in the field of microalgae biodiesel. Studies show that regulating light, temperature, pH, nutrients, etc. can improve the growth and oil production of microalgae, in which the addition of anions and cations can change the physiological, biochemical and metabolic mechanisms of microalgae. At present, a large number of genetic modification and metabolic regulation engineering technologies are applied to microalgae oil production. They have precise control of the targeting mechanism in cells to induce increased lipid accumulation. The two-stage culture model can simultaneously increase biomass and lipid content. The addition of homogeneous, heterogeneous, biological enzymes and nano-catalysts accelerates the conversion efficiency and improves the yield of biodiesel. The catalytic yield of several magnetic nano-catalysts studied is as high as > 98 %. The supercritical method and ionic liquid method are favored by everyone because they do not use catalysts to reduce environmental pollution. In situ transesterification replaces the traditional two-step transesterification method to reduce energy consumption and cumbersome steps. Hydrothermal liquefaction method can directly convert wet algae biomass into biofuels without drying at high temperatures and pressure and in the presence of water. However, the current high-cost economic problems in the production of microalgae biodiesel and the environmental problems caused by the addition of catalysts need to further study the efficient and low-cost microalgae culture methods and new environmentally friendly catalysts and catalytic methods to improve the yield of microalgae biodiesel, to realize the commercial production of microalgae biodiesel as soon as possible.
Display omitted
•The conditions affecting the growth and oil production of microalgae were reviewed.•The effects of anions and cations on the growth of microalgae were introduced.•The genetic metabolism regulation of microalgae oil production was introduced.•Different catalysts and catalytic methods in biodiesel production were compared.•The limitations and prospects of microalgae biodiesel were discussed.
In this paper, higher-order correlation clustering (HOCC) is used for text line detection in natural images. We treat text line detection as a graph partitioning problem, where each vertex is ...represented by a Maximally Stable Extremal Region (MSER). First, weak hypothesises are proposed by coarsely grouping MSERs based on their spatial alignment and appearance consistency. Then, higher-order correlation clustering (HOCC) is used to partition the MSERs into text line candidates, using the hypotheses as soft constraints to enforce long range interactions. We further propose a regularization method to solve the Semidefinite Programming problem in the inference. Finally we use a simple texton-based texture classifier to filter out the non-text areas. This framework allows us to naturally handle multiple orientations, languages and fonts. Experiments show that our approach achieves competitive performance compared to the state of the art.
Inland lakes and rivers are large reservoirs of microplastics. But currently, not too much research was done on microplastics of mountain rivers. The protection of water sources from microplastics is ...extremely significant for the safety of human drinking water. We quantified the distribution and variation of microplastics in the surface water from tributary (upstream water-source regions) to main stream (human settlements) in the Chin Ling-Wei River Plain Rivers, and assessed the pollution risk. Rivers in the Chin Ling-Wei River Plain contained various levels of microplastics (2.30–21.05 items/L), and the main stream of the river contained higher concentrations most commonly of microplastics than tributaries. The microplastics were fragments and films; they constituted 82.3% of the total abundance of microplastics. Microplastics with a particle size < 500 µm accounted for 64.3% of all the samples. As rivers flow from the mountains to the plains, the land-use types along the rivers become more multifunctional. Thus, the risk of river microplastic pollution increases sharply with distance downstream. Our research explored the microplastics pollution in the Chin Ling mountains based on topography and land-use types and thus provides a reference for further studies exploring the spatial distribution characteristics of microplastics in small-scale rivers and for pollution risk assessments.
Display omitted
•Microplastics in small-scale rivers of mountain-plain transitional area were quantified.•Microplastics pollution in mountainous areas came from agriculture and tourism.•Urbanization increased the risk of microplastics pollution in rivers.•River embankment protection projects led to an increase in microplastics.
This study was conducted to investigate the effects of fructooligosaccharide (FOS) and Bacillus licheniformis (B. licheniformis) and their interaction on innate immunity, antioxidant capability and ...disease resistance of triangular bream Megalobrama terminalis (average initial weight 30.5 ± 0.5 g). Nine experimental diets were formulated to contain three FOS levels (0, 0.3% and 0.6%) and three B. licheniformis levels (0, 1 × 10(7), 5 × 10(7) CFU g(-1)) according to a 3 × 3 factorial design. At the end of the 8-week feeding trial, fish were challenged by Aeromonas hydrophila (A. hydrophila) and survival rate was recorded for the next 7 days. The results showed that leucocyte counts, alternative complement activity as well as total serum protein and globulin contents all increased significantly (P < 0.05) as dietary B. licheniformis levels increased from 0 to 1 × 10(7) CFU g(-1), while little difference (P > 0.05) was observed in these parameters in terms of dietary FOS levels. Both plasma alkaline phosphatase and phenoloxidase activities were significantly (P < 0.05) affected only by dietary FOS levels with the highest values observed in fish fed 0.6 and 0.3% FOS, respectively. Both immunoglobulin M content and liver superoxide dismutase (SOD) activity were significantly affected (P > 0.05) by both FOS and B. licheniformis. Liver catalase, glutathione peroxidase as well as plasma SOD activities of fish fed 1 × 10(7) CFU g(-1)B. licheniformis were all significantly (P < 0.05) higher than that of the other groups, whereas the opposite was true for malondialdehyde content. After A. hydrophila challenge, survival rate was not affected (P > 0.05) by either FOS levels or B. licheniformis contents, whereas a significant (P < 0.05) interaction between these two substances was observed with the highest value observed in fish fed 0.3% FOS and 1 × 10(7) CFU g(-1)B. licheniformis. The results of this study indicated that dietary FOS and B. licheniformis could significantly enhance the innate immunity and antioxidant capability of triangular bream, as well as improve its disease resistance. The best combination of these two prebiotics and/or probiotics was 0.3% FOS and 1 × 10(7) CFU g(-1)B. licheniformis.
This study investigated the effects of dietary protein/energy (P/E) ratio and water temperature on growth performance, blood biochemistry, digestive enzymes activity and innate immunity of spotted ...seabass (Lateolabrax maculatus). Six diets were formulated to contain two protein (440 and 470 g/kg) and three lipid levels (80, 110 and 140 g/kg) with P/E ratios of 22.31, 23.27, 23.47, 24.05, 24.35 and 25.55 g/MJ. Each diet was fed to two different sets of fish (2.67 ± 0.01 g) kept at low temperature (27°C; LT) or high temperature (33°C; HT). Triplicate groups of fish were fed to apparent satiation three times daily for 8 weeks. The highest weight gain values were obtained at P/E ratios of 24.35 (470 g/kg protein and 110 g/kg lipid) and 23.47 (470 g/kg protein and 140 g/kg lipid) at LT and HT, respectively. Feed conversion ratio (FCR) was also significantly influenced by dietary P/E ratios where the lowest FCR was found in fish received the diet with P/E of 22.31 and kept at LT. Intestinal protease, amylase and lipase activities were neither affected by dietary P/E ratios nor water temperature. Significantly higher hepatic citrate synthase and succinate dehydrogenase activities were detected in LT groups. All serum innate immune parameters including lysozyme, complements 3 and 4, immunoglobulin and alkaline phosphatase were decreased by increasing water temperature. The findings in this study showed that optimal P/E ratios for spotted seabass at 27 and 33°C are 22.31 and 23.47 g/MJ, respectively, and that high temperature induces retarded growth and suppressed immune function.
In this rapidly developing society, it is always crucial to exploit new materials with suitable properties to meet specific application demands. Two-dimensional (2D) transition metal carbon/nitrides ...(MXenes) are a novel graphene-like material with exciting research potential in recent years. Among them, Ti
3
C
2
debuts in a central position due to its relatively longer research history, mature synthetic process, and incredibly rich store of merits, such as good flexibility, large specific surface area, abundant termination groups, excellent electrical conductivity, and light-to-heat conversion ability. In this review, recent research progress on Ti
3
C
2
MXene and its composites was updated mainly from three aspects, including their fundamentals, synthesis, and applications. It has been found that diverse applications of Ti
3
C
2
-based composites are inseparable and correlated with each other, which were linked by their unique physicochemical properties. In the end, a summary and a perspective on future opportunities and challenges of Ti
3
C
2
were given to offer theoretical and technical guidelines for further investigation on MXene family.
In this paper, a fractional Zakharov-Kuznetsov equation with He's fractional
derivative is studied by the fractional complex transform and He's homotopy
perturbation method. The solution process is ...elucidated step by step to
show its simplicity and effectiveness of the proposed method.
nema
Herein, the new collected well-testing temperature as well as continuous steady-state temperature logs were achieved for the analysis of deep thermal structural characteristics and current thermal ...states of various tectonic units in Tarim Basin. Generally, geothermal gradient fluctuates in 14.6-31.1°C/km, the heat flow ranges between 31.6 and 59.2 mW/m2 with the average heat flow of 43.2 mW/m2, and these values are typical of low heat flow background in Precambrian craton basins. Furthermore, estimated formation temperature spatial distributions at 6∼8 km depth are the same and are mainly under the control of basement structural pattern. At 6000 m depth, temperature is 99-188°C, which become 126-242°C and 113-215°C at 7000 m and 8000 m depths, respectively. These findings confirmed that heat flow in Tarim Basin was relatively low with similar geothermal regimes to other Precambrian craton basins around the globe. In addition, 1D theoretical crustal thermal structures in Tarim Basin were established based on the solution of the equation of steady-state heat conduction. The findings revealed that "thermal" lithosphere maximum thickness in Tarim Basin is witnessed in Manjiaer sag. Tazhong uplift thermal state differs from those of Tabei uplift and Manjiaer sag. Tazhong mantle heat flow is 23.9 mW/m2, which accounts for 48.8% of surface heat flow. Hotter thermal states of Tazhong uplift generated temperatures as high as ∼690°C in Moho. Tarim Basin heat flow distribution reveals that crustal heat flow plays a more significant role in surface heat flow and possesses typical "hot crust and cold mantle" model thermal structure properties.
Grasslands are the dominant landscape in China, accounting for 40% of the national land area. Research concerning China's grassland ecosystems can be chronologically summarized into four periods: (i) ...pre-1950s, preliminary research and survey of grassland vegetation and plant species by Russians, Japanese and Western Europeans, (ii) 1950-1975, exploration and survey of vegetation, soils and topography as part of natural resource inventory programmes by regional and national institutions mainly led by the Chinese Academy of Sciences, (iii) 1976-1995, establishment of field stations for long-term ecological monitoring and studies of ecosystem processes, (iv) 1996-present, comprehensive studies of community dynamics and ecosystem function integrating multi-scale and multidisciplinary approaches and experimental manipulations. Major findings of scientific significance in China's grassland ecosystem research include: (i) improved knowledge on succession and biogeochemistry of the semi-arid and temperate grassland ecosystems, (ii) elucidation of life-history strategies and diapause characteristics of the native grasshopper species as one of the key grassland pests, and (iii) development of effective management strategies for controlling rodent pests in grassland ecosystems. Opportunities exist for using the natural grasslands in northern China as a model system to test ecosystem theories that so far have proven a challenge to ecologists worldwide.
Metarhizium is a group of insect-pathogenic fungi that can produce insecticidal metabolites, such as destruxins. Interestingly, the acridid-specific fungus Metarhizium acridum (MAC) can kill locusts ...faster than the generalist fungus Metarhizium robertsii (MAA) even without destruxin. However, the underlying mechanisms of different pathogenesis between host-generalist and host-specialist fungi remain unknown. This study compared transcriptomes and metabolite profiles to analyze the difference in responsiveness of locusts to MAA and MAC infections. Results confirmed that the detoxification and tryptamine catabolic pathways were significantly enriched in locusts after MAC infection compared with MAA infection and that high levels of tryptamine could kill locusts. Furthermore, tryptamine was found to be capable of activating the aryl hydrocarbon receptor of locusts (LmAhR) to produce damaging effects by inducing reactive oxygen species production and immune suppression. Therefore, reducing LmAhR expression by RNAi or inhibitor (SR1) attenuates the lethal effects of tryptamine on locusts. In addition, MAA, not MAC, possessed the monoamine oxidase (Mao) genes in tryptamine catabolism. Hence, deleting MrMao-1 could increase the virulence of generalist MAA on locusts and other insects. Therefore, our study provides a rather feasible way to design novel mycoinsecticides by deleting a gene instead of introducing any exogenous gene or domain.
PDF
