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The BeiDou Global Satellite Navigation System (BDS-3) broadcast newly developed B1C and B2a signals. To provide a better service for global users, the vertical phase center offset (PCO) and phase center variation (PCV) are estimated for the B1C/B2a ionospheric-free linear combination of the BDS-3 inclined geostationary orbit (IGSO) and medium earth orbit (MEO) satellites in this study. And considering the traditional PCC estimation method needs two Precise orbit determination (POD) processing, based on the correlation between PCO z-offset and PCV, the theoretical analysis and experimental comparison have been made to discuss whether the POD procedure for the PCO estimation can be omitted. The estimated z-offset time series revealed the inadequacy of the solar radiation pressure (SRP) model for the IGSO satellites and the MEO satellites with Pseudo Random Noise code (PRN) C45 and C46. The PCVraws estimated by the traditional method and the PCO estimation omitted method have the same characteristic. The final PCO z-offsets and PCVs calculated by the two schemes agreed very well with differences can be harmlessly ignored, which confirmed that the PCO estimation can be safely omitted to save computation time. The PCC model proposed in this study has been compared with the Test and Assessment Research Center of China Satellite Navigation Office (TARC/CSNO) released model, the qualities of the orbits and BDS-only precise point positioning (PPP) solutions of the new model both show improvements, except for the IGSO orbits. The analysis of the IGSO orbits further verifies the SRP model is not suitable for the IGSO satellites. [ABSTRACT FROM AUTHOR]

The fusion of light detection and ranging (LiDAR) and camera data is a promising approach to improve the environmental perception and recognition for intelligent vehicles because of the combination of depth and color information. One of the difficulties in achieving the fusion is the accurate alignment of the 3-D points with the image pixels. Current methods of data alignment involve the steps of estimating the camera intrinsic parameters and developing a transformation matrix between the camera and LiDAR frame. The drawback of these methods is the accumulation of errors during the calculation of the camera intrinsic parameters and the transformation matrix. In order to improve the data alignment accuracy, we propose a novel algorithm that directly calculates the alignment between the 3-D points and the pixels without the need for camera parameters and calibration of the coordinate transformation matrix. We call the proposed method the pixel and 3-D point alignment (PPA) method. The alignment procedure is achieved by using the extracted corresponding points. First, we calculate a linear alignment matrix without considering the image distortion; and second, we optimize the parameters using the maximum likelihood estimation to consider the camera distortion. Simulation and experimental results indicate that the PPA method is able to align the 3-D points in LiDAR frame with the pixels in image frame with higher accuracy and increased robustness against noise in calibration process than comparable state-of-the-art methods. [ABSTRACT FROM AUTHOR]

A six-week feeding trial was conducted to evaluate the effects of dietary isoleucine level on growth, myofiber histology, and mRNA levels of genes related to amino acid, glucose and lipid metabolism in swimming crab (Portunus trituberculatus). Six isonitrogenous and isolipidic diets (45% protein and 8% lipid) were formulated to contain graded levels of isoleucine (Ile), with the analyzed levels of isoleucine being 0.69%, 1.06%, 1.32%, 1.78%, 2.03% and 2.38%, respectively. A total of 180 crabs (initial weight 16.30 ± 0.01 g) were housed individually in 180 plastic baskets with 30 crabs assigned to each diet, divided randomly into three replicates of 10 crabs. Each crab was fed twice at 08:00 and 18:00 with a daily feeding ration of 6–8% of crab body weight. Eight crabs from each replicate group were sampled and dissected after the feeding trial to provide hemolymph for biochemical analysis, hepatopancreas for proximate composition, amino acid profile enzyme activity, and gene expression, and muscle for proximate composition, amino acid profile and histology. The results indicated that final weight, percent weight gain and specific growth rate increased significantly as dietary isoleucine level increased from 0.69% to 1.78%, and then decreased with further increased dietary isoleucine. Crabs fed the diets with 1.78%, 2.03% and 2.38% isoleucine showed significantly higher muscle protein contents (17.80%, 17.99% and 17.65% of wet mass) than crabs fed lower levels of isoleucine. The highest concentrations of IGF1R and CHH in hemolymph (187.95 and 529.42 pg ml−1, respectively) and hepatopancreas (24.18 and 38.69 pg ml−1, respectively) were observed in crabs fed the diet with 1.32% isoleucine. Hepatopancreas expression levels of genes related to amino acid metabolism, including s6k1 , bcat , alt and ast , were up-regulated in crabs fed 1.32% isoleucine compared to the other groups, whereas the expression level of tor decreased as dietary isoleucine increased. Expression levels of genes related to glucose intake, such as pi3k , igf1r and glut1 , were significantly higher in crabs fed 1.32% isoleucine compared to crabs fed 0.69% isoleucine. Expression levels of genes related to gluconeogenesis (pepck and g6pase) were significantly higher in crabs fed 0.69% isoleucine than in crabs fed the diets with 1.32% and 1.78% isoleucine. In contrast, expression levels of genes related to glycolysis, including hk , gk and pk , were up-regulated in crabs fed 1.32% isoleucine compared to crabs fed 0.69% isoleucine. Gene expression levels of regulatory factors related to lipid metabolism (foxo , sirt1 and sirt3) were significantly higher in crabs fed 1.32% isoleucine compared to crabs fed the other treatments, while expression levels of genes related to lipolysis (hsl and cpt2) were significantly up-regulated in crabs fed the diets with 1.32% and 1.78% isoleucine. Expression levels of key lipogenesis genes (fas and acc) were down-regulated in crabs fed the diets with 1.32% and 1.78% isoleucine compared to those fed 0.69% isoleucine. Muscle histology indicated that crabs fed the diets with 1.32% and 1.78% isoleucine had significantly lower densities of myofibers (21.67 and 17.33 N/ mm2) compared to crabs fed 0.69% isoleucine. In conclusion, based on percent weight gain, the optimal isoleucine requirement of juvenile swimming crab was calculated to be 1.57% of diet (3.49% dietary protein) by quadratic curve model. Thus, appropriate dietary isoleucine levels (1.32–1.78%) promoted amino acid metabolism and protein synthesis, increased protein deposition, and altered myofiber structure of muscle and, in addition, promoted lipolysis and glycolysis, and reduced lipogenesis and gluconeogenesis in juvenile swimming crab. • Based on PWG, the optimal dietary isoleucine requirement for P. trituberculatus was to be 1.57%. • Increasing dietary isoleucine in the range 1.78%–2.38% promoted protein deposition in body muscle. • Isoleucine at 1.32% of diet up-regulated expression levels of genes related to amino acid metabolism in hepatopancreas. • Isoleucine at 1.32% of diet increased hepatic glycogen content by activating glycolysis and suppressing gluconeogenesis. • 1.32%−1.78% isoleucine of diet increased hepatopancreatic lipid catabolism via activation of the foxo-sirt1/sirt3 pathway. [ABSTRACT FROM AUTHOR]

Slurries of canna starch treated with or without α-amylase were heated at 60 °C to investigate the mechanism of thermal and enzymatic degradation and the effects of these processes on the ultrastructure of starch residues. For this purpose, solid-state 13 C CP/MAS NMR, X-ray diffraction (XRD), and small angle X-ray scattering (SAXS) were used to estimate the short- and long-range orders within the structure. Crystal stabilization was observed in both samples of thermally degraded canna starch (TDCS) and enzymatically degraded canna starch (EDCS), and the critical time for the formation of double helical crystals was 3 h for thermal degradation and 5 h for enzymatic degradation. With longer times, imperfect sub-crystal started prevailed. The results showed that when degradation occurs, the crystal lamellae compact, as indicated by a higher crystal density in the structure of EDCS. Moreover, the relationship between crystalline weight and volume fraction as well as short-range and long-range orders were also investigated and found correlate well with each other. [ABSTRACT FROM AUTHOR]

The effect of thermal and enzymatic degradation on the physicochemical properties and in vitro digestibility of canna starch was investigated. Microscopic observation reveals that pores approximately 1 µm in diameter were obvious on the surface of enzymatically degraded canna starch (EDCS), and the formation of the cavum was found in the center of the starch granules. Physicochemical properties show that a transformation from soluble to insoluble amylose was observed in the thermal degraded canna starch (TDCS), and a sharp increase in water solubility index (WSI) was found in EDCS. The highest content of resistant starch (RS) (40.05%) was observed in EDCS-3, which was evidenced by the reappearance of soluble amylose in EDCS-5. As a whole, thermal degradation simultaneously perfected the crystalline structure and facilitated the process of gelatinization. Enzymatic degradation, on the other hand, is a net result of thermal and pure enzymatic degradation, and therefore resulted in a much more complex degradation pattern. [ABSTRACT FROM AUTHOR]

An eight-week feeding trial was conducted to evaluate the effect of dietary replacement of fish meal with low-gossypol cottonseed protein concentrate (CPC) on growth performance, body composition, amino acid profiles in tissues, antioxidant capacity and the expression levels of genes related to protein metabolism and inflammation for juvenile swimming crab (Portunus trituberculatus). Six isonitrogenous and isolipidic diets (450 g kg−1 protein and 80 g kg−1 lipid) were formulated to contain graded levels of CPC, and fish meal was replaced with CPC at 0, 10%, 20%, 30%, 40% and 60% levels (CPC00, CPC10, CPC20, CPC30, CPC40 and CPC60), free gossypol concentrations in experimental diets were analyzed to be 0, 32.62, 66.10, 106.71, 133.13, 192.21 mg kg−1 respectively. Arginine, lysine and methionine were added to ensure consistency of these three essential amino acids in all experimental diets. Each diet was randomly assigned to triplicate groups of 30 juvenile swimming crabs (approximately initial weight 7.59 ± 0.06 g) that were stocked in rectangle plastic baskets. Results of present study indicated that crabs fed the CPC60 diet had the lower final weight (FW), percent weight gain (PWG), specific growth rate (SGR) and feed efficiency (FE) than those fed the CPC20 diet, and crabs fed the CPC20 and CPC30 diets had the highest survival among all treatments, and the lowest survival was occurred at crabs fed the CPC60 diet. The hepatopancreas color was blackened with the replacement levels of fish meal with CPC increasing from 0% to 60%. Free gossypol concentration in hepatopancreas significantly increased with increase of dietary replacement levels of fish meal with CPC. Crabs fed the CPC40 and CPC60 diets had lower lipid content in whole body than those fed the other diets. Arginine, lysine, methionine and isoleucine contents in muscle were significantly influenced by dietary replacement levels of fish meal with CPC. ALT, AST, TP, ALB, HDL and ALP in hemolymph, and T-AOC, ALT, AST, SOD, GSH, GSH-ST in hepatopancreas were significantly affected by dietary replacement of fish meal with CPC. Dietary replacement levels of fish meal with CPC could influence the expressions of genes related into protein metabolism such as tor , akt , s6 , s6k1 , 4ebp1 , eif4e1a , eif4e2 , eif4e3 , antioxidant and immune such as gpx, cat, cMnsod and lysozyme , as well as growth such as tlr4 , irak4 , myd88 , traf6 , and inflammation such as relish. In conclusion, based on two slope broken-line and quadratic broken-line regression analysis of PWG against the dietary replacement of fish meal with CPC, the optimal replacement level of fish meal with CPC was estimated to be 19.07% and 22.73% for juvenile swimming crab, respectively. Results demonstrated that CPC could partially replace fish meal, but had no negative effects on growth performance, antioxidant activity and immunity of swimming crab. • The optimal replacement level of FM with CPC was 19.07–22.73% for swimming crab based on PWG. • Hepatopancreas free gossypol concentration significantly increased with increase of dietary CPC. • Replacement of FM with CPC influenced expression of genes related to mTOR pathway and inflammation. [ABSTRACT FROM AUTHOR]

The third generation of the BeiDou navigation satellite system (BDS-3) can transmit five-frequency signals. The real-time satellite clock offset of BDS-3 is typically generated utilizing the B1I/B3I combination with the ambiguity-float solutions. By conducting the ambiguity resolution (AR), the reliability of the satellite clock offset can be improved. However, the performance of BDS-3 ambiguity-fixed real-time satellite clock offset with B1C/B2a signals remains unknown and unrevealed. In this contribution, the performance of the BDS-3 ambiguity-fixed satellite clock offset with the new B1C/B2a signals is investigated. One week of observation data from 85 stations was used to perform ambiguity-fixed satellite clock offset estimation. For B1I/B3I and B1C/B2a signals, the wide-lane (WL) uncalibrated phase delay (UPD) on the satellite end is fairly stable for one day, while the narrow-lane (NL) UPD standard deviation (STD) amounts to 0.122 and 0.081 cycles, respectively. The mean ambiguity fixing rate is 80.7% and 78.0% for these two signal combinations, and the time to first fix (TTFF) for the B1C/B2a signals is remarkably shorter than that of the B1I/B3I signals. The STDs of the ambiguity-float and -fixed satellite clock offsets are 0.033 and 0.026 ns, respectively, for the B1I/B3I combination, and it is reduced to 0.024 and 0.023 ns for B1C/B2a signals, respectively. Using the estimated UPD and clock offset products, the positioning performance of the kinematic Precise Point Positioning (PPP)-AR results amounts to 1.56, 1.23, and 4.46 cm in the east, north, and up directions for B1I/B3I signals, respectively. It is improved to 1.36, 1.16, and 4.25 cm using the products estimated with the B1C/B2a signals, with improvements of 12.8%, 5.7%, and 4.7% in three directions, respectively. The experiments showed that the performances of the ambiguity-fixed satellite clock offsets and the PPP-AR results using B1C/B2a signals are better than those of B1I/B3I. [ABSTRACT FROM AUTHOR]

The quality of crustacean aquatic products is affected by feed. Cholesterol (CHO), an essential element for crustacean growth, has been widely supplemented in diet, but its food quality regulation remains unclear. The study aimed to investigate the effects of different dietary CHO levels (0.12%, 1.00%, and 2.50%) on the nutritional value and flavor quality in the edible parts of female swimming crabs (Portunus trituberculatus). Results showed that dietary CHO levels significantly increased lipid content in the hepatopancreas and promoted the accumulation of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in the hepatopancreas and muscle by activating the gene expression related to biosynthesis pathways. However, with dietary CHO levels increased, protein content in muscle decreased significantly. This may be related to dietary CHO supplementation (especially 2.50% CHO level) suppressed amino acid accumulation in the hepatopancreas and muscle by downregulating the target of the rapamycin pathway and upregulating amino acid catabolism-related genes. Moreover, 1.00% CHO treatment had higher relative levels of volatiles, producing grassy, fruity, and fatty odors in muscle, which may be due to the upregulation of the branched-chain amino acid transaminase (bcat) expression level. Dietary CHO weakened nucleotide and free amino acid accumulation in hepatopancreas and muscle. Overall, this study suggests that dietary 1.00% CHO level had higher LC-PUFA and pleasing flavor substances in muscle but was not conducive to hepatopancreatic protein and flavor nucleotide deposition of swimming crab. [ABSTRACT FROM AUTHOR]

• We use tire forces to assess driving risk. • All tire forces are estimated by using cascaded observers with only low-cost sensors. • Estimation of tire forces does not need sideslip angle with the proposed models. • Tire forces are predicted by getting upcoming road geometry from ADAS map. This work aims to develop a driving risk warning system to enhance the road safety. Different from the existing lane departure warning system, speed limit warning system or collision warning system, the warning system proposed in this work focuses on the safety regarding vehicle's dynamics states. Many road accidents are caused by losing control of vehicle dynamics, such as the rollover, car drift and brake failure. First of all, the importance of monitoring vehicle dynamics states, especially the tire forces, is explained. Then the driving risk assessment criteria based on tire forces are developed in this work. The main contribution of this paper is the development of vehicle dynamics models and observers to estimate and predict individual tire forces using only low-cost sensors and ADAS (Advanced Driver Assistance Systems) map. The major new techniques developed in this study can be summarized in three aspects: (1) development of new vehicle dynamics models to estimate vertical, longitudinal, and lateral tire forces, (2) development of new nonlinear observers to minimize the estimation errors caused by sensor noises and model uncertainty, and (3) development of the tire forces prediction algorithm by taking advantage of digital map. The proposed warning system is validated by real vehicle experiments. [ABSTRACT FROM AUTHOR]

• A new evaluation method considering periodic errors for GNSS atomic clocks on board is proposed. • The correlation relationship between the sun elevation and orbit radial error, fitting precision, frequency stability, amplitude is revealed. • The evaluation results of GPS satellite clocks in orbit that more approach to the real performance are obtained. The performance of the atomic clock in orbit is of terrific significance for the Global Navigation Satellite System (GNSS). With the rapid development of satellite navigation and atomic clock technology, the periodic error of satellite clocks caused by the environment is more prominent. This paper focuses on the analysis and quantification of the systematic periodic error in the clock offset and proposes a more accurate evaluation method for GPS satellite clocks. The fact that the J2 relativistic effect and orbit radial error are the main sources of the systematic periodic term has been revealed. Then, the Fast Fourier Transform (FFT) is employed using the sliding window to investigate the periodic influence caused by satellite orbit and the J2 relativistic effect on clock offset through six GPS satellites with different orbital planes, these satellites also cover all four types of GPS satellite blocks. The results show that there is an obvious relationship between the sun elevation and orbit radial error, clock offset fitting precision, frequency stability and amplitude. The different geometric configurations of the satellite and the varying environment make this relationship different. Based on the clock offset provided by European Space Agency (ESA), the period of clock offset is extracted and quantized, with the period of 24 h, 12 h, 8 h, 6 h, 4 h, and 3 h. According to the daily extraction results of the time-varying periodic terms, the two most noticeable terms correction on satellite clock offset has been proven to be effective in eliminating periodic errors. Compared to those without periodic correction, the fitting precision and frequency stability can improve by 48.5% and 42.6%, respectively. In addition, all GPS satellite clocks in orbit are evaluated by this periodic correction method, and the results are more approach to the actual performance of the satellite clock. Furthermore, this method can also be adapted to evaluate satellite clocks of other GNSS systems. Therefore, when we evaluate the high-precision atomic clock flying on board GNSS satellites and compare them with the manufacturers' specifications, the periodic error cannot be neglected. [ABSTRACT FROM AUTHOR]

Cholesterol and phospholipid play an important role in growth, molt and reproduction for crustaceans, although dietary optimum requirement of cholesterol and phospholipids has been determined for Portunus trituberculatus , but it is still unclear whether there was an interaction on each other. Therefore, an eight-week feeding trial was conducted to evaluate the interactive effects of dietary cholesterol and phospholipid levels on growth performance, fatty acid composition in hepatopancreas and the expression of genes related to cholesterol and phospholipid metabolism of Portunus trituberculatus. Six isonitrogenous and isolipid diets were formulated to contain two cholesterol levels (0 % and 0.5 %) and three phospholipid levels (0 %, 2 % and 4 %). The results indicated that specific growth rate (SGR) significantly increased with the increase of dietary phospholipid levels, however, there were no interactive effects between dietary cholesterol and phospholipid on percent weight gain (PWG) and SGR (P > 0.05). The concentration of total-cholesterol (T-CHO) and triacylglycerol (TAG) in hemolymph significantly affected by the interaction between cholesterol and phospholipid (P < 0.05), crabs fed diets with 0.5 % cholesterol supplementation had higher low-density lipoprotein cholesterol (LDL-C) concentration in hemolymph than those fed diets without cholesterol supplementation regardless of phospholipid supplementation (P < 0.05). TAG and LDL-C concentration in hepatopancreas were significantly affected by the interaction between cholesterol and phospholipid (P < 0.05), crabs fed diets with 0.5 % cholesterol supplementation had significantly higher T-CHO and LDL-C concentration in hepatopancreas than those fed diets without cholesterol supplementation (P < 0.05). There was a significant interaction between dietary cholesterol and phospholipid on activity of catalase (CAT) and the concentration of glutathione (GSH) and malondialdehyde (MDA) in hepatopancreas (P < 0.05), and crabs fed diets with cholesterol supplementation had higher superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in hepatopancreas than those fed diets without cholesterol supplementation (P < 0.05). Moreover, EPA, LC-PUFA, n-3 PUFA, n-3/n-6 PUFA and DHA/E P A in hepatopancreas were significantly affected by the interaction between dietary cholesterol and phospholipid (P < 0.05). The expression of adenosine triphosphate binding cassette transporter G1 (abcg1), C-type 1 class Niemann-Pick protein (npc1), scavenger receptor B (srb) and low-density lipoprotein receptor (ldlr) were up-regulated by dietary cholesterol and phospholipid levels (P < 0.05). In conclusion, the results indicated that dietary appropriate cholesterol and phospholipid levels could significantly improve growth performance and promote cholesterol metabolism. • Interaction between dietary cholesterol and phospholipid did not affect growth performance of swimming crabs. • Interaction between dietary cholesterol and phospholipid could enhance antioxidant capacity of swimming crab. • Dietary cholesterol regulated cholesterol metabolic pathways in hepatopancreas of swimming crab. • Interaction between cholesterol and phospholipid up-regulated the expression of genes related to cholesterol and phospholipid metabolism. • Interaction between cholesterol and phospholipid could promote cholesterol transport and transformation. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was carried out to assess the effect of dietary krill meal on growth performance and expression of genes related to TOR pathway and antioxidation of swimming crab (Portunus trituberculatus). Four experimental diets (45% crude protein and 9% crude lipid) were formulated to obtain different replacements of fish meal (FM) with krill meal (KM); FM was replaced with KM at 0% (KM0), 10% (KM10), 20% (KM20), and 30% (KM30); fluorine concentration in diets were analyzed to be 27.16, 94.06, 153.81, and 265.30 mg kg-1, respectively. Each diet was randomly divided into 3 replicates; ten swimming crabs were stocked in each replicate (initial weight, 5.62 ± 0.19 g). The results indicated that crabs fed with the KM10 diet had the highest final weight, percent weight gain (PWG), and specific growth rate (SGR) among all treatments (P < 0.05). Crabs fed with the KM0 diet had the lowest activities of total antioxidant capacity (T-AOC), total superoxide dismutase (SOD), glutathione (GSH), and hydroxyl radical scavenging activity and had the highest concentration of malondialdehyde (MDA) in the hemolymph and the hepatopancreas (P < 0.05). In the hepatopancreas, the highest content of 20:5n-3 (EPA) and the lowest content of 22:6n-3 (DHA) were shown in crabs fed with the KM30 diet among all treatments (P < 0.05). With the substitution level of FM with KM gradually increasing from 0% to 30%, the color of the hepatopancreas changed from pale white to red. Expression of tor, akt, s6k1, and s6 in the hepatopancreas was significantly upregulated, while 4e-bp1, eif4e1a, eif4e2, and eif4e3 were downregulated with dietary replacement of FM with KM increasing from 0% to 30% (P < 0.05). Crabs fed with the KM20 diet had notably higher expression of cat, gpx, cMnsod, and prx than those fed with the KM0 diet (P < 0.05). Results demonstrated that 10% replacement of FM with KM can promote growth performance and antioxidant capacity and notably upregulate the mRNA levels of genes related to TOR pathway and antioxidant of swimming crab. [ABSTRACT FROM AUTHOR]

Carbohydrate is the cheapest source of energy among the three major nutrient groups, an appropriate amount of carbohydrates can reduce feed cost and improve growth performance, but carnivorous aquatic animals cannot effectively utilize carbohydrates. The objectives of the present study are aimed at exploring the effects of dietary corn starch levels on glucose loading capacity, insulin-mediated glycemic responses, and glucose homeostasis for Portunus trituberculatus. After two weeks of feeding trial, swimming crabs were starved and sampled at 0, 1, 2, 3, 4, 5, 6, 12, and 24 hours, respectively. The results indicated that crabs fed diet with 0% corn starch exhibited lower glucose concentration in hemolymph than those fed with the other diets, and glucose concentration in hemolymph remained low with the extension of sampling time. The glucose concentration in hemolymph of crabs fed with 6% and 12% corn starch diets reached the peak after 2 hours of feeding; however, the glucose concentration in hemolymph of crabs fed with 24% corn starch attained the highest value after 3 hours of feeding, and the hyperglycemia lasted for 3 hours and decreased rapidly after 6 hours of feeding. Enzyme activities in hemolymph related to glucose metabolism such as pyruvate kinase (PK), glucokinase (GK), and phosphoenolpyruvate carboxykinase (PEPCK) were significantly influenced by dietary corn starch levels and sampling time. Glycogen content in hepatopancreas of crabs fed with 6% and 12% corn starch first increased and then decreased; however, the glycogen content in hepatopancreas of crabs fed with 24% corn starch significantly increased with the prolongation of feeding time. In the 24% corn starch diet, insulin-like peptide (ILP) in hemolymph reached a peak after 1 hour of feeding and then significantly decreased, whereas crustacean hyperglycemia hormone (CHH) was not significantly influenced by dietary corn starch levels and sampling time. ATP content in hepatopancreas peaked at 1 h after feeding and then decreased significantly in different corn starch feeding groups, while the opposite trend was observed in NADH. The activities of mitochondrial respiratory chain complexes I, II, III, and V of crabs fed with different corn starch diets significantly increased first and then decreased. In addition, relative expressions of genes related to glycolysis, gluconeogenesis, glucose transport, glycogen synthesis, insulin signaling pathway, and energy metabolism were significantly affected by dietary corn starch levels and sampling time. In conclusion, the results of the present study reveal glucose metabolic responses were regulated by different corn starch levels at different time points and play an important role in clearing glucose through increased activity of insulin, glycolysis, and glycogenesis, along with gluconeogenesis suppression. [ABSTRACT FROM AUTHOR]

Starches from five underutilized tubers (canna, potato, Chinese yam, water chestnut, and taro) were extracted to investigate quantitative structure–property relationships (QSPR) in each starch using a combination of X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS). Structural parameters of the tuber starches were determined using the paracrystalline model. Swelling power (SP), water solubility index (WSI), amylose leaching (AML), and thermal properties were also measured. The XRD results indicated that starches from Chinese yam, water chestnut, and taro are C-type starches with relatively high crystallinity (29.23–35.02%). In contrast, canna and potato starches are B-type starches exhibiting lower crystallinity and higher amylose content. The paracrystalline model provided a better fit for the C-type starches than for the B-type starches because the former was highly compressible (indicated by a higher “ β ” value). B-type starches, on the other hand, tend to be more rigid along the lamellar repeat direction, requiring the layers to bend to accommodate internal stress. The QSPR analysis showed that three structural parameters, “ Ø ”, “ β ”, and “ Δ ρ u ”, correlate well with the SP and WSI, and thus can be used to predict certain physicochemical properties. [ABSTRACT FROM AUTHOR]

This experiment was conducted to evaluate the effects of different carbohydrate levels on the growth performance, glycogen accumulation in tissue, enzyme activities, and expression levels of genes related to hepatopancreatic glucose and lipid metabolism and insulin signaling pathway in swimming crab, Portunus trituberculatus for 8 weeks. The results indicated that crabs fed with the 60.0 g kg-1 carbohydrate diet exhibited the highest final body weight (FBW), percent weight gain (PWG), and specific growth rate (SGR) among all treatments. FBW, PWG, and SGR significantly decreased when dietary carbohydrate levels exceeded 240.0 g kg-1. Light microscopy results showed that dietary excessive carbohydrate levels will lead to vacuole, hepatopancreatic tubule lysis, and lipid droplets in hepatopancreas. Expression levels of genes involved into glucose transport, glucose and lipid metabolism, and insulin-like metabolism in the hepatopancreas were significantly influenced by dietary carbohydrate levels. In general, the results of present study demonstrated that dietary optimal carbohydrate levels could not only improve PWG and SGR but also influence the expression of genes involved in glucose, lipid, and insulin-like metabolism. The optimal actual carbohydrate level was estimated to be 87.8-98.4 g kg-1 based on broken-line and second-order polynomial regression analysis between PWG against dietary carbohydrate levels for juvenile Portunus trituberculatus. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of tributyrin (TB) supplementation on the growth, digestive enzyme activity, lipid metabolism, and intestinal health of swimming crab (Portunus trituberculatus) with an initial weight of 12.50 ± 0.02 g. Six experimental diets were formulated, which containing 0%, 0.025%, 0.05%, 0.10%, 0.20%, and 0.40% of TB, respectively. Results showed that crabs fed the diet containing 0.10% TB had significantly higher values of percent weight gain (PWG) and specific growth rate (SGR) than those in other treatments. Crabs fed the diet without TB supplementation showed dramatically higher contents of T-CHO, TG, and MDA in serum than those in other treatments, opposite patterns were recorded for the activities of T-SOD, PPO, NO, ACP, and AKP. The activities of antioxidant enzyme including T-AOC, T-SOD, ACP, AKP and GSH-Px in hepatopancreas were significantly affected by dietary TB levels. Meanwhile, crabs fed the diet without TB supplementation had significantly lower activities of trypsin, lipase, and amylase in the intestine than those in other treatments. The relative expression levels of genes related to antioxidant capacity in the hepatopancreas and intestine were markedly decreased when crabs fed the diet without TB supplementation; however, crabs fed the diet without TB supplementation exhibited the highest expression of genes linked to inflammation among treatments, and the expression levels of crustin and lyso in the intestine were significantly affected by dietary TB levels. The expression levels of genes related to energy metabolism and intestinal immune barrier in the intestine were also influenced by dietary TB levels. Dietary TB supplementation could reduce lipid accumulation in hepatopancreas by upregulating lipid catabolism related genes expression levels and decreasing lipid anabolism related gene expression levels. Muscularis thickness, fold width, and fold height in the intestine were significantly increased with dietary TB increasing from 0% to 0.10%; moreover, lipid droplets, the diameter of R cells and the area of R cells in the hepatopancreas significantly decreased with an increase of dietary TB levels. Additionally, the number of Actinobacteria and Bacteroides significantly increased with an increase of dietary TB levels. To sum up, the TB requirement of swimming crab was 0.089% based on two slope broken-line analysis of PWG. The findings of the current study indicate that TB is an effective growth promoter that can serve as a nutritional supplement to improve the growth performance, promote health and regulate lipid metabolism of swimming crab. Fig. 1. Schematic presentation of Graphical Abstract. [Display omitted] • Tributyrin had positive effects on growth performance of Portunus trituberculatus. • Based on PWG, the optimal dietary tributyrin requirement for P. trituberculatus was to be 0.089%. • Tributyrin supplementation enhanced digestive enzyme activity and antioxidant capacity of intestine. • Tributyrin increased the abundance of potential probiotics in intestine of crab. • Tributyrin supplementation affected lipid metabolism. [ABSTRACT FROM AUTHOR]

The service areas of the BeiDou Navigation Satellite System (BDS) are China, the Asia–Pacific, and the world via three stages of development. The BDS constellation is designed to maintain a geostationary Earth orbit (GEO), inclined geosynchronous orbit (IGSO), and medium Earth orbit (MEO). These orbital maneuvers yield certain difficulties for data processing, especially for the BeiDou satellites, such as a decrease in the real-time service performance, which causes a missing precise orbit product from the maneuvered satellites. The frequencies of the orbital maneuvers for the GEO and IGSO satellites are higher than those for the MEO satellites. The maneuvering time and strategy cannot be obtained by common users due to secrecy, which can yield a decline in the service performance of the BDS. Thus, in this study, we analyzed the variation in the orbital semimajor axis for the satellites. The long-term variation in the orbital semimajor axis changes linearly. The short-term variation in the orbital semimajor axis also has periodicity, which can be described by the sum of sine functions. According to the long-term variation in the orbital semimajor axis for the satellites, we propose a detection method for in-plane orbital maneuvering of the GEO, IGSO, and MEO satellites. We then propose a detection method for out-of-plane maneuvering of the GEO satellites. BDS and Global Positioning System (GPS) data from the broadcast ephemeris were analyzed to verify the proposed methods. The experimental results from 2013 to 2019 show that the frequency of orbital maneuvering is approximately once a month for the GEO satellites, once every six months for the IGSO satellites, and once every 1.4 years for the MEO satellites. [ABSTRACT FROM AUTHOR]

The atomic clock is the core of the Global Navigation Satellite System (GNSS), which plays an important role in Positioning, Navigation and Timing (PNT) services. However, the long-term characteristics of the global BeiDou navigation system (BeiDou-3) and comparison of satellite clocks performance for the five GNSSs have not yet been revealed. We evaluated and analysed the performance of atomic clocks for BeiDou-3 and other GNSSs using satellite clock offset data. The important contributions are summarised as follows. (1) The phase and frequency sequences of Passive Hydrogen Maser (PHM) and rubidium (Rb) atomic clocks for BeiDou-3 are more stable and continuous than those of the regional BeiDou navigation system (BeiDou-2). The clock offset model precision and average frequency stability at 10,000, 1000, and 100 s for the BeiDou-3 satellite clock offsets are 0.15 ns and 6.8 × 10–14, respectively, exhibiting significant improvements compared with those for BeiDou-2. (2) The performance of cesium (Cs) atomic clocks installed on Global Positioning System (GPS) Block IIF are more inferior than Global Navigation Satellite System (GLONASS), which may be due to the poor level of Cs atomic clock manufacturing technology or obvious noise characteristics. Thus, more attention should be paid to these two satellite clocks. (3) A comparison of various indicators revealed that the satellite clocks for Galileo are the best, followed by BeiDou-3, GPS Block IIF satellites with Rb atomic clocks, Quasi-Zenith Satellite System (QZSS), BeiDou-2, GLONASS, GPS Block IIR, and Block IIR-M. The GPS Block IIF satellites equipped with a Cs atomic clock shows the poorest performance. [ABSTRACT FROM AUTHOR]

This study investigated the influences of dietary zinc (Zn) on lipid and fatty acid metabolism of Scylla paramamosain. Three diets containing analyzed Zn levels including 44.5 (low Zn), 68.5 (medium Zn) and 254.7 (high Zn) mg/kg were prepared and fed to mud crab for 10 weeks, respectively. Medium dietary Zn levels improved the growth of mud crab than those fed the high Zn diet. The concentration of Zn in tissues was positively correlated with dietary Zn levels. Crabs fed with high Zn diet significantly decreased lipid content in hepatopancreas and muscle when compared to those fed the medium Zn diet. The lowest diameter, area and number of R cell in hepatopancreas histology were observed in those fed the high Zn diet. Furthermore, medium levels of dietary Zn significantly increased docosahexaenoic acid (DHA) and n-3 polyunsaturated fatty acid (PUFA) contents in hepatopancreas. Crabs fed high Zn diet dramatically down-regulated expression of acc , fas , g6pd , 6pgd and srebp , but up-regulated expression of aco3 , cpt1 and fabp1 in hepatopancreas. Crabs fed with medium Zn diet significantly increased the mRNA levels of fad in hepatopancreas. In summary, the results of present study emphasized the adverse effects of excess dietary Zn (254.7 mg/kg) on suppress hepatopancreatic lipid and n-3 PUFA accumulation, dietary 68.5 mg/kg Zn level was recommended to maintain optimal lipid and fatty acid metabolism of mud crab. • High levels dietary Zn caused lipid depletion in hepatopancreas and muscle of mud crab. • High levels dietary Zn restrained lipogenesis and promoted lipolysis of hepatopancreas. • Medium levels dietary Zn increased hepatopancreatic DHA and n-3 PUFA accumulation. [ABSTRACT FROM AUTHOR]

The positioning, navigation, and timing (PNT) service of the Global Navigation Satellite System (GNSS) is developing in the direction of real time and high precision. However, there are some problems that restrict the development of real-time and high-precision PNT technology. Satellite orbit maneuvering is one of the factors that reduce the reliability of real-time navigation products, especially the high-frequency orbit maneuvering of geostationary earth orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites. The BeiDou Navigation Satellite System (BDS) constellation is designed to contain GEO, IGSO, and medium earth orbit (MEO). These orbit maneuvers bring certain difficulties for data processing, especially for BeiDou satellites, such as decreased real-time service performance, which results in real-time navigation products including unusable maneuvered satellites. Additionally, the performance of real-time navigation products will decrease because the orbit maneuvers could not be known in advance, which diminishes the real-time PNT service performance of BDS for users. Common users cannot obtain maneuvering times and strategies owing to confidentiality, which can lead to a decline in the BDS real-time service performance. Thus, we propose a method to predict orbit maneuvers. BDS data from the broadcast ephemeris were analyzed to verify the availability of the proposed method. In addition, the results of real-time positioning were analyzed by using ultra-rapid orbit products, demonstrating that their reliability is improved by removing maneuvered satellites in advance. This is vital to improve the reliability of real-time navigation products and BDS service performance. [ABSTRACT FROM AUTHOR]

Satellite antenna phase center offsets (PCOs) and phase variations (PVs) for BeiDou-3 satellites are estimated based on the tracking data of the Multi-GNSS Experiment (MGEX) and the international GNSS Monitoring and Assessment System (iGMAS) network. However, when estimating the (PCOs) of BeiDou-3 medium Earth orbit (MEO) satellites by pure Extending the CODE Orbit Model (ECOM1), the x-offset estimations of the PCOs have a systematic variation of about 0.4 m with the elevation of the Sun above the orbital plane (β-angle). Thus, a priori box-wing solar radiation pressure (SRP) model of BeiDou-3 MEO was assisted with ECOM1. Then, the satellite type-specific PCOs and common PVs were obtained. The estimations of PCOs and PVs were compared with the MGEX PCOs from the precise orbit and clock offset. When the MGEX PCOs were used, the root mean square (RMS) of 24 h overlap was 6.76, 4.36, 1.46 cm, in along-track, cross-track, and radial directions, respectively; the RMS and standard deviations (STD) of the 24 h clock offset overlap were 0.28 and 0.15 ns; the fitting RMS of the 72 h clock offset of the quadratic polynomial was 0.243 ns. After comparing this with the estimated PCOs and PVs, the RMS of the 24 h orbit overlap was decreased by 6.5 mm (10.54%), 1.8 mm (4.4%), and 1.1 mm (8.03%) in the along-track, cross-track, and radial directions, respectively; the RMS and STD of the 24 h clock offset overlap were decreased by 0.024 ns (8.6%) and 0.020 ns (13.1%), respectively; the fitting RMS of the 72 h clock offset of the quadratic polynomial was reduced by about 0.016 ns (6.5%). [ABSTRACT FROM AUTHOR]

In order to provide better service for the Asia-Pacific region, the BeiDou navigation satellite system (BDS) is designed as a constellation containing medium earth orbit (MEO), geostationary earth orbit (GEO), and inclined geosynchronous orbit (IGSO). However, the multi-orbit configuration brings great challenges for orbit determination. When orbit maneuvering, the orbital elements of the maneuvered satellites from broadcast ephemeris are unusable for several hours, which makes it difficult to estimate the initial orbit in the process of precise orbit determination. In addition, the maneuvered force information is unknown, which brings systematic orbit integral errors. In order to avoid these errors, observation data are removed from the iterative adjustment. For the above reasons, the precise orbit products of maneuvered satellites are missing from IGS (international GNSS (Global Navigation Satellite System) service) and iGMAS (international GNSS monitoring and assessment system). This study proposes a method to determine the precise orbits of maneuvered satellites for BeiDou GEO and IGSO. The initial orbits of maneuvered satellites could be backward forecasted according to the precise orbit products. The systematic errors caused by unmodeled maneuvered force are absorbed by estimated pseudo-stochastic pulses. The proposed method for determining the precise orbits of maneuvered satellites is validated by analyzing data of stations from the Multi-GNSS Experiment (MGEX). The results show that the precise orbits of maneuvered satellites can be estimated correctly when orbit maneuvering, which could supplement the precise products from the analysis centers of IGS and iGMAS. It can significantly improve the integrality and continuity of the precise products and subsequently provide better precise products for users. [ABSTRACT FROM AUTHOR]

Due to the cuboid satellite body of BeiDou-3 satellites, the accuracy of their orbit showed a trend of systematic variation with the sun-satellite-earth angle (ε) using the Extend CODE Orbit Model (ECOM1). Therefore, an a priori cuboid box-wing model (named the cuboid model) is necessary to compensate ECOM1. Considering that the body-dimensions and optical properties of the BeiDou-3 satellites used to construct the box-wing model have not yet been fully released, the adjustable box-wing model (ABW) was used for precise orbit determination (POD). The a priori cuboid box-wing model was directly estimated by the precision radiation accelerations, obtained from ABW POD. When using ECOM1 model, for 14 < β < 40°, a linear systematic variation of D0 related to the elevation of the sun above the orbital plane (β-angle) with a slope of 0.048 nm/s2/°, was found for C30. After adding the cuboid model to assist ECOM1 (named Cuboid + ECOM1), the slope was reduced to 0.005 nm/s2/°, and for C20 satellite, the standard deviation (STD) of D0 was improved, from 1.28 to 0.85 nm/s2 (34%). For satellite laser ranging (SLR) validation, when using the ECOM1 model, the systematic variation with the ε angle was about 14 cm for C20 and C30. After using the Cuboid + ECOM1 model, the variation was significantly reduced to about 5 cm. For C20 and C21, compared with the ECOM1 model, the root mean square (RMS) of the ECOM2 and Cuboid + ECOM1 model was improved by about 0.54 (10.3%) and 0.43 cm (8.7%). For C29 and C30, the RMS of ECOM2 and Cuboid + ECOM1 model was improved for about 0.7 (10.9%) and 1.6 cm (25.6%). Finally, the RMS of the SLR residuals of 4.37 to 4.88 cm was achieved for BeiDou-3 POD. [ABSTRACT FROM AUTHOR]

Because there are different types of BeiDou constellations with participating geostationary orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites, the maneuvering frequency of BeiDou satellites is higher than that of other navigation systems. The satellite orbital maneuvers lead to orbital parameter failure for several hours from broadcast ephemeris. Due to the missing initial orbit, the maneuvering thrust, and the period of orbital maneuvering, the orbit products of maneuvering satellites cannot be provided by the International Global Navigation Satellite System (GNSS) Service (IGS) and International GNSS Monitoring and Assessment System (iGMAS). In addition, the period of unhealthy status and the orbital parameters of maneuvering satellites in broadcast ephemeris are unreliable, making the detection of orbital maneuver periods more difficult. Here, we develop a method to detect orbital maneuver periods involving two key steps. The first step is orbit prediction of maneuvering satellites based on precise orbit products. The second step is time period detection of orbit maneuvering. The start time detection factor is calculated by backward prediction orbit and pseudo-range observations, and the end time detection factor is calculated by forward prediction orbit and pseudo-range observations. Data of stations from the Multi-GNSS Experiment (MGEX) and iGMAS were analyzed. The results show that the period of orbit maneuvering could be detected accurately for BeiDou GEO and IGSO satellites. In addition, the orbital maneuver period of other GNSS medium Earth orbit (MEO) satellites could also be determined by this method. The results of period detection for orbit maneuvering provide important reference information for precision orbit and clock offset determination during satellite maneuvers. [ABSTRACT FROM AUTHOR]