Tolerance Range Research Articles

Coarse-proxy reduced basis methods for integral equations

In this paper, we introduce a new reduced basis methodology for accelerating the computation of large parameterized systems of high-fidelity integral equations. Core to our methodology is the use of coarse-proxy models (i.e., lower resolution variants of the underlying high-fidelity equations) to identify important samples in the parameter space from which a high quality reduced basis is then constructed. Unlike the more traditional POD or greedy methods for reduced basis construction, our methodology has the benefit of being both easy to implement and embarrassingly parallel. We apply our methodology to the under-served area of integral equations, where the density of the underlying integral operators has traditionally made reduced basis methods difficult to apply. To handle this difficulty, we introduce an operator interpolation technique, based on random sub-sampling, that is aimed specifically at integral operators. To demonstrate the effectiveness of our techniques, we present two numerical case studies, based on the radiative transport equation and a boundary integral formation of the Laplace equation respectively, where our methodology provides a significant improvement in performance over the underlying high-fidelity models for a wide range of error tolerances. Moreover, we demonstrate that for these problems, as the coarse-proxy selection threshold is made more aggressive, the approximation error of our method decreases at an approximately linear rate. Finally, we provide a public repository of our source code with easy instructions for reproducing all results in this paper.

Performance analysis of a robust design optimization of a solenoid with different sensitivity metrics

Optimization is an essential part of designing electrical machines and devices. Considering the uncertainties and tolerances from the beginning of the design process can lead to a more robust design and significantly reduce the number of waste products during the manufacturing process. However, the computational demand for these robust design optimization problems is amazingly high. This paper examines how the computational demand and the robustness of the results depend on the applied sensitivity metric. The multi-objective TEAM 35 benchmark problem has been used as the basis of the comparison. This optimization task aims to create a homogeneous magnetic field in a predefined coil region, which is insensitive to the positioning errors of the coil turns. The original definition of the problem uses a simple worst-case sensitivity metric calculated from the extreme values of the optimized turn parameters in the given tolerance range. This sensitivity metric has been replaced by Plackett–Burman, Box–Behnken, and Central Composite Design-based metrics. It was shown in this simple geometry that there is a significant difference between the resulting sensitivities. Nevertheless, Plackett–Burman and Central Composite Design provided the more accurate and consistent estimate of the sensitivity of the examined layouts, with a higher but still reasonable computation demand than the worst-case metric.

Experimental tolerance design of robot manipulators accounting for positioning accuracy reliability

AbstractA new tolerance design method based on experimental design and positioning accuracy reliability is presented to deal with uncertainties of robot manipulators resulting from manufacturing and assembly processes. Initially, the performance function of positioning accuracy is established according to the kinematic model and response surface technique. An analytical algorithm for positioning accuracy reliability calculation is developed based on eigen‐decomposition and saddlepoint approximation methodologies. Inner orthogonal arrays of kinematic parameter tolerances along with the outer uniform arrays of joint variables are then constructed to analyze significant tolerances that affect the positioning accuracy reliability within the entire workspace. Finally, the applicability and performance of the proposed method are verified by case studies of a two‐link planar manipulator and a six‐degree‐of‐freedom robot manipulator. The results confirmed that the proposed method can efficiently and accurately analyze the positioning accuracy reliability, and the method recognizes the impact of kinematic parameters on the motion performance which is able to guide the tolerance range selection of robot manipulators.

Spatial variability of life-history parameters of the Atlantic chub mackerel (Scomber colias), an expanding species in the northeast Atlantic

Atlantic chub mackerel is a pelagic species present in the Atlantic Ocean that in recent decades has expanded northwards in the eastern Atlantic. Fish samples were collected in scientific surveys and commercial catches between 2011 and 2019. We analysed the geographical variation of the biological parameters (age, length, weight and condition), as well as the length-weight relationship, maturity-at-length and spawning season onset and duration in five geographical areas (from south to north): the Canary Islands, Gulf of Cadiz, western Portuguese coast, northwestern Spanish coast and Cantabrian Sea. The influence of sea surface temperature (SST) on fish length was modelled as a potential driver of geographical variability. All biological parameters increased progressively northwards, while the spawning season was delayed and prolonged with increasing latitude, from January in the Canary Islands to May-August in the Cantabrian Sea, when SST was between 15°C and 19°C. SST had a positive effect on length in three study areas and a negative one in two of them, suggesting that each group is at a different position within their thermal tolerance range. Deviance from the geographical pattern of some biological parameters in the Gulf of Cadiz suggests that it could be a hinge or mixing zone between Atlantic African, Mediterranean and Atlantic Iberian population components.

Gene Expression Profiling of Trematomus bernacchii in Response to Thermal and Stabling Stress

The Antarctic continent is one of the most pristine environments on planet Earth, yet one of the most fragile and susceptible to the effects of the ongoing climate change. The overwhelming majority of the components of Antarctic marine trophic chain are stenotherm organisms, highly adapted to the extreme, but extremely stable, freezing temperatures of the Antarctic ocean, which have not changed significantly during the past fifteen million years. Notothenioid fishes are the most abundant representatives of ichthyofauna at these latitudes, being ubiquitously found in coastal areas across the entire continent. While different Antarctic fish species have been previously subjected to studies aimed at defining their range of thermal tolerance, or at studying the response to acute thermal stress, just a handful of authors have investigated the effects of the exposure to a moderate increase of temperature, falling within the expected forecasts for the next few decades in some areas of the Antarctica. Here, the emerald rockcod Trematomus bernacchii was used as a model species to investigate the effects of a 20-day long exposure to a +1.5 °C increase in the brain, gills and skeletal muscle, using a RNA-sequencing approach. In parallel, the experimental design also allowed for assessing the impact of stabling (including acclimation, the handling of fishes and their confinement in tanks during the experimental phase) on gene expression profiling. The results of this study clearly identified the brain as the most susceptible tissue to heat stress, with evidence of a time-dependent response dominated by an alteration of immune response, protein synthesis and folding, and energy metabolism-related genes. While the gills displayed smaller but still significant alterations, the skeletal muscle was completely unaffected by the experimental conditions. The stabling conditions also had an important impact on gene expression profiles in the brain, suggesting the presence of significant alterations of the fish nervous system, possibly due to the confinement to tanks with limited water volume and of the restricted possibility of movement. Besides providing novel insights in the molecular mechanisms underlying thermal stress in notothenioids, these findings suggest that more attention should be dedicated to an improved design of the experiments carried out on Antarctic organism, due to their extreme susceptibility to the slightest environmental alterations.

Tolerance Analysis of Cylindrical Roller Bearing under Combined Radial and Axial Loads

In order to analyze the influence of tolerance values of key parameters for cylindrical roller bearings under combined axial and radial loads, a coupled model, incorporating a dynamic model of cylindrical roller bearings, contact model, and fatigue life model, is developed to investigate the effect of flange angle, roller-end radius, interval of roller length gauge, and roller profile on contact performance and fatigue life. The results show that the grouping design of flange angle and roller-end radius in the tolerance range was helpful for reducing contact ellipse truncation. The difference of the roller length would change the axial load distribution of the bearings. For the longest roller located in the bottom position, the bigger the difference, the bigger the roller tilt angle and carried-axial load. The (0, +2.5 μm) tolerance range of the crown drop can limit the difference of the fatigue life within 20% in the current analysis.

Capacitor voltages balancing method for buck modular DC/DC converter

The most critical problem of the modular DC-DC converter (MDCC) is the voltage balancing of the submodule (SM) capacitors, the MDCC with stepped 2-level modulation has been developed and presents a good solution, however, this type of modulation has many restrictions when there is a wide range of capacitance tolerance of the SM capacitors that results inaccurate capacitor voltages balancing. To solve this problem, this paper discusses a proposed method of capacitor voltage balancing. Compared with stepped 2-level modulation, the voltage balancing method using modified duty cycle modulation offers the merits: i) reduction in output voltage and SM capacitor voltages overshoot during dynamic operation and improvement in the time response of the system and; ii) accurate voltage balancing over wide range of capacitance tolerance of each SM capacitor; and iii) the sorting algorithm replaced with modified duty cycle modulation method for the SM capacitor voltages balancing which reduces the computation burden. The proposed method ensures a stable voltage balancing, improves the time response of the system, and decreases the voltage and current overshoot during the dynamic response compared with prior art of MDCCs, where the stepped 2-level modulation is adopted. An analytical simulation of the MDCC is presented using MATLAB/Simulink to explain the operation.

Research and experiment on control loop system of Source Measure Unit

Aiming at the problem that the capacitive load of the source measure unit (SMU) system affects the stability of the loop control, this paper makes an in-depth theoretical analysis of the loop control system based on the SMU. A theoretical and circuit model is established after the analysis. In the control loop structure, an integrator with proportional amplification serves as an error amplifier for the control loop system to obtain sufficient phase margin at the optimal bandwidth. A phase-lead compensation capacitor scheme is studied and proposed to achieve the maximum tolerance range to achieve the loop stability. The results show that the simulation and experimental results are basically consistent. The results verify the theoretical correctness and practical value of this SMU control loop system, and provide a theoretical basis for the research of the SMU control loop structure of the subsequent SIP process.

Design and Modeling of Array-Type MRF Support for Shallow Spherical Shell

A shallow spherical shell is a typical weak-stiffness aerospace structure, which is always expected to have less or no deformation in machining. To control the shell deformation, magnetorheological fluid (MRF) is introduced to support a shallow spherical shell since it has high controllability with the help of external magnetic field. To minimize shell deformation, adopted MRF support should be determined according to the varying loads, but the optimal MRF support has not been designed and modeled. In this paper, to generate magnetic field with controllable strength/region, an array-type MRF support device is parametrically designed first. To characterize the shell deformation process in array-type MRF support device, a sequential MRF support model is established. Based on the sequential MRF support model, the optimal magnetic field layout is modeled and furtherly calculated on FE platform. At last, shell deformation under optimal magnetic field layout was experimentally compared with other support conditions. Experiment results indicate that optimized array-type MRF support can effectively control the shell deformation within a tight tolerance range.

Effects of Salinity on Clay Flocculation in the Context of Mitigating Karenia Brevis Blooms in the Tampa Bay

Objective: Tampa Bay Area is an estuary and thus has varying levels of salinity, so it has become imperative to determine whether or not the leading combat strategy (clay flocculation) to HABs is effective under these differing conditions. Method: an experiment was conducted that measured the settling rates of Kaolin clay at varying levels of salinity (0, 17.5, 30, and 45 Parts Per Thousand) within the range of Karenia Brevis. Results: There is no statistically significant difference between the settling rates of Kaolin clay within the range of tolerance of K. Brevis, and therefore can be used to combat K. Brevis blooms in Tampa Bay regardless of salinity.

How Can Climate Change Limit the Distribution of Cooperative Pseudoscorpions in Brazil?

Pseudoscorpions are arachnids that inhabit all terrestrial ecosystems, and are distributed in the tropical, subtropical, and even circumpolar regions. Paratemnoides nidificator (Balzan, 1888) was originally distributed in the continental zone of South America, but subsequently dispersed to Centraland NorthAmerica and the Caribbean. This species was also recorded in coastal marine environments and forest areas in continental and insular regions. Paratemnoides nidificator is the only cooperatively social pseudoscorpion species recorded in South American. However, its distribution limitations are poorly understood. In this study, we used ecological niche models to investigate this species' current and future distribution potential. Similarly, we defined range limits and demonstrated the potential species distribution towards the Cerrado and Atlantic Forest biomes in the Brazilian territory in future scenarios of climate change, and land use and land cover changes. The annual mean temperature was the most important variable, suggesting that a physiological limitation prevents P. nidificator from occupying areas with extreme mean temperatures. Furthermore, the loss of vegetation cover and the expansion of agricultural frontiers may reduce the occurrence of P. nidificator in environmentally unstable areas because P. nidificator is sensitive to anthropogenic activities. Therefore, the biological response is the relationship between the tolerance limit of P. nidificator and the predicted amplitude of the factor, which appears to lie in its maximum tolerance range.

Field Measurements and Analysis on Temperature, Relative Humidity, Airflow Rate and Oil Fume Emission Concentration in a Typical Campus Canteen Kitchen in Tianjin, China

This study investigated the annual variation of the indoor thermal environment in a typical canteen kitchen and tried to evaluate the actual working status of the exhaust fume system. Parameters were measured in the canteen kitchen, including indoor environment (temperature, humidity, air velocity); outdoor environment (temperature; humidity); exhaust fume system (temperature, airflow rate, oil fume concentration, energy consumption), and makeup air system (temperature, humidity, air velocity) from April 2019 to January 2020. In addition, we also interviewed the chef’s thermal comfort in this kitchen. From the data available, we could find that 82.92% of the working hours in summer were above the acceptable range. Only 17.08% of the working hours were within the tolerance range (26–32 °C). The questionnaire results showed that 83.33% of chefs felt hot in summer. Most chefs’ wet sensations in the four seasons were neutral, and 91.6% of the chefs felt dissatisfied with the draft sensation. In addition, 88.33% of the chefs felt the fume overflowing from the exhaust hood. This may be because the exhaust fume system of the canteen kitchen was operated under the air velocity of 9.18 ± 1.6 m/s, and its exhaust airflow rate was 10,634.80 ± 189.30 m3/h, which is lower than the minimum exhaust airflow rate (12,312 m3/h). The measurement results indicated that the exhaust fume system could not remove the waste heat and fume pollutants effectively.

Shifts of ammonia-oxidation process along salinity gradient in an estuarine wetland

Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) play an important role in nitrogen (N) cycling of the estuarine sediments. However, the shifts of potential ammonia oxidation rates (PARs) of AOA and AOB along different salinity gradients are not well understood. Here, salinity-treated (0, 5, 15, 25 and 35 ‰) incubation experiments of sediment from the Pearl River Estuary were performed to explore the influence of salinity on ammonia oxidation process, including the PARs and gene abundances of AOA and AOB. Significant shifts of PARs and amoA gene abundances of ammonia oxidation process along salinity gradient were observed during the incubation (0–60 d). After a long-term incubation, both PARtotal (4.61 ± 0.93 μg N g−1 d−1) and PARaob (3.05 ± 1.04 μg N g−1 d−1) reached their maximum values at 25 ‰ salinity, and PARaoa (1.96 ± 0.10 μg N g−1 d−1) reached its maximum values at 35 ‰ salinity, which showed that PARs had higher values under high salinity conditions. AOB amoA gene was more abundant than AOA under moderate and high salinity, and only a significant linear correlation was observed between PARaob and AOB abundances. In addition, the ammonia oxidation activities showed a wide range of salinity tolerance, which is worthy of further study on community structure and transcript richness. Our study illustrates that salinity plays a key role in regulating the ammonia oxidation process in estuarine sediments, and has guiding significance for N fixation and N loss associated with saltwater incursion.

Germination of Seeds Subjected to Temperature and Water Availability: Implications for Ecological Restoration

The regeneration of natural Betula platyphylla Suk., a pioneer tree and predominant species in stand forest of the northern region, China faces a challenge, i.e., population decline. One of the bottlenecks relative to the successful seedling establishment is the effectiveness of seed germination. In this study, four different families (3-4, 3-22, 3-42, and 3-43) of B.platyphylla seeds were used as research objects to explore the effects of temperature and PEG simulated drought on seed germination. The result showed that seed germination ability from different families increased first and then decreased with the increase in temperature. The germination rate (GR), germination value coefficient (GVC), and germination index (GI) at 25 ℃ and 30 ℃ were significantly higher than those at lower temperatures (15 ℃ and 20 ℃) and higher temperature (35 ℃), and the time for germination percentage to reach 50% (T50) was faster. The germination ability decreased gradually with the increase in drought stress. Seeds are more sensitive to drought stress at low temperatures, their germination is severely inhibited, and the tolerance range of PEG concentration at 15 °C (0%–10%) is less than other temperatures (10%–20%), while they can germinate well at high temperatures and the tolerance to drought stress is stronger. Our results suggested that 3-43 had better germination ability at high temperature, while 3-22 had better germination ability at low temperature. Our findings highlight low temperatures and drought stress as key factors limiting seed germination, which may be one of the bottlenecks to population regeneration. This research provides a scientific reference for the natural regeneration and population restoration of B. platyphylla.

A multifaceted field sampling approach for the management of extremely narrow endemic vascular plant species.

Extremely narrow endemic plant species (ENEs) are generally connected with microrefugia characterized by particular environmental conditions. In-depth knowledge of the ecological requirements of ENEs is fundamental to plan appropriate conservation measures. Using cross-cutting technology, this paper gives a multifaceted approach to collect on-site data on the ecology of ENEs, defines the protocols for a correct sampling design and describes the type of equipment, the time and expenditure needed. Our sampling approach is based on two orthogonal transects, long enough to extrapolate the whole ecological gradient across the area of occupancy of the target species. Microclimatic data are recorded all along the transects through iButton technology, plus a weather station installed at the intersection of the transects. Microtopographic data are recorded with high-resolution digital elevation model and sub-metric GPS. Edaphic data are recorded along the transects through standard soil analyses and on-site evaluation of the seasonal decomposition rate of organic matter. Additionally, vegetation sampling in 4m2 plots and on-site germination tests allow to collect data on auto- and synecological factors that regulate the life cycle of the target species. Our approach has proved to be cost-effective and efficient in terms of time spent in the field against the data collected. The most demanding activities were the establishment of the transects and the vegetation sampling. The time spent downloading microclimatic data and testing seed germination was relatively short. Our sampling design allows: (i) to catch as much micro-topographic variability as possible, both within and out of the tolerance range of the target species, (ii) to minimize the risk of recording identical micro-topographic conditions compared with a random sampling scheme, and (iii) to ensure quick and relatively easy retrieval of the plots and the equipment both on a multi-seasonal and multi-annual basis.

(Pre)diabetes, glycemia, and daily glucose variability are associated with retinal nerve fiber layer thickness in The Maastricht Study

Retinopathy and neuropathy in type 2 diabetes are preceded by retinal nerve fibre layer (RNFL) thinning, an index of neurodegeneration. We investigated whether glucose metabolism status (GMS), measures of glycaemia, and daily glucose variability (GV) are associated with RNFL thickness over the entire range of glucose tolerance. We used cross-sectional data from The Maastricht Study (up to 5455 participants, 48.9% men, mean age 59.5 years and 22.7% with type 2 diabetes) to investigate the associations of GMS, measures of glycaemia (fasting plasma glucose [FPG], 2-h post-load glucose [2-h PG], HbA1c, advanced glycation endproducts [AGEs] assessed as skin autofluorescence [SAF]) and indices of daily GV (incremental glucose peak [IGP] and continuous glucose monitoring [CGM]-assessed standard deviation [SD]) with mean RNFL thickness. We used linear regression analyses and, for GMS, P for trend analyses. We adjusted associations for demographic, cardiovascular risk and lifestyle factors, and, only for measures of GV, for indices of mean glycaemia. After full adjustment, type 2 diabetes and prediabetes (versus normal glucose metabolism) were associated with lower RNFL thickness (standardized beta [95% CI], respectively − 0.16 [− 0.25; − 0.08]; − 0.05 [− 0.13; 0.03]; Ptrend = 0.001). Greater FPG, 2-h PG, HbA1c, SAF, IGP, but not CGM-assessed SD, were also associated with lower RNFL thickness (per SD, respectively − 0.05 [− 0.08; − 0.01]; − 0.06 [− 0.09; − 0.02]; − 0.05 [− 0.08; − 0.02]; − 0.04 [− 0.07; − 0.01]; − 0.06 [− 0.12; − 0.01]; and − 0.07 [− 0.21; 0.07]). In this population-based study, a more adverse GMS and, over the entire range of glucose tolerance, greater glycaemia and daily GV were associated with lower RNFL thickness. Hence, early identification of individuals with hyperglycaemia, early glucose-lowering treatment, and early monitoring of daily GV may contribute to the prevention of RNFL thinning, an index of neurodegeneration and precursor of retinopathy and neuropathy.

Green oxidative rearrangement of indoles using halide catalyst and hydrogen peroxide

Oxidative rearrangement of indoles is an essential transformation that has been widely used in the synthesis of many pharmaceutical agents and bioactive natural products. Herein, we report an efficient, practical and metal-free method for the oxidative rearrangement of indoles to spirooxindoles, 2-oxindoles, 2,2-disubstituted indolin-3-ones, and oxa-spirooxindoles using 10 mol% HBr and hydrogen peroxide as the terminal oxidant. The protocol displays a broad substrate scope (35 examples) and a wide range of functional group tolerance and has been applied in the synthesis of (±)-coerulescine and the formal synthesis of (±)-horsfiline. Notably, the distinct advantages of this protocol involve metal-free catalysis, waste prevention, and simple operation.

Genomics and cellulolytic, hemicellulolytic, and amylolytic potential of Iocasia fonsfrigidae strain SP3-1 for polysaccharide degradation.

BackgroundCellulolytic, hemicellulolytic, and amylolytic (CHA) enzyme-producing halophiles are understudied. The recently defined taxon Iocasia fonsfrigidae consists of one well-described anaerobic bacterial strain: NS-1T. Prior to characterization of strain NS-1T, an isolate designated Halocella sp. SP3-1 was isolated and its genome was published. Based on physiological and genetic comparisons, it was suggested that Halocella sp. SP3-1 may be another isolate of I. fronsfrigidae. Despite being geographic variants of the same species, data indicate that strain SP3-1 exhibits genetic, genomic, and physiological characteristics that distinguish it from strain NS-1T. In this study, we examine the halophilic and alkaliphilic nature of strain SP3-1 and the genetic substrates underlying phenotypic differences between strains SP3-1 and NS-1T with focus on sugar metabolism and CHA enzyme expression.MethodsStandard methods in anaerobic cell culture were used to grow strains SP3-1 as well as other comparator species. Morphological characterization was done via electron microscopy and Schaeffer-Fulton staining. Data for sequence comparisons (e.g., 16S rRNA) were retrieved via BLAST and EzBioCloud. Alignments and phylogenetic trees were generated via CLUTAL_X and neighbor joining functions in MEGA (version 11). Genomes were assembled/annotated via the Prokka annotation pipeline. Clusters of Orthologous Groups (COGs) were defined by eegNOG 4.5. DNA-DNA hybridization calculations were performed by the ANI Calculator web service.ResultsCells of strain SP3-1 are rods. SP3-1 cells grow at NaCl concentrations of 5-30% (w/v). Optimal growth occurs at 37 °C, pH 8.0, and 20% NaCl (w/v). Although phylogenetic analysis based on 16S rRNA gene indicates that strain SP3-1 belongs to the genus Iocasia with 99.58% average nucleotide sequence identity to Iocasia fonsfrigida NS-1T, strain SP3-1 is uniquely an extreme haloalkaliphile. Moreover, strain SP3-1 ferments D-glucose to acetate, butyrate, carbon dioxide, hydrogen, ethanol, and butanol and will grow on L-arabinose, D-fructose, D-galactose, D-glucose, D-mannose, D-raffinose, D-xylose, cellobiose, lactose, maltose, sucrose, starch, xylan and phosphoric acid swollen cellulose (PASC). D-rhamnose, alginate, and lignin do not serve as suitable culture substrates for strain SP3-1. Thus, the carbon utilization profile of strain SP3-1 differs from that of I. fronsfrigidae strain NS-1T. Differences between these two strains are also noted in their lipid composition. Genomic data reveal key differences between the genetic profiles of strain SP3-1 and NS-1T that likely account for differences in morphology, sugar metabolism, and CHA-enzyme potential. Important to this study, I. fonsfrigidae SP3-1 produces and extracellularly secretes CHA enzymes at different levels and composition than type strain NS-1T. The high salt tolerance and pH range of SP3-1 makes it an ideal candidate for salt and pH tolerant enzyme discovery.

Biochemical characterization and elucidation the degradation pattern of a new cold-adapted and Ca2+ activated alginate lyase for efficient preparation of alginate oligosaccharides

Alginate lyase as the excellent tool enzyme could produce alginate oligosaccharides under mild reaction conditions and good specificity. Herein, the new Ca2+ activated alginate lyase gene (TAPL7B) with metal ions stability and cold-adapted was cloned and expressed heterologously from Thalassotalea algicola. TAPL7B was identified as a polysaccharide lyases family 7 (PL7) alginate lyase with endolytic activity. TAPL7B is a polyM-preferred and cold-adapted enzyme with an optimal temperature of 20 °C and pH 11.0. The pH stability analysis indicated that TAPL7B possessed broad pH tolerant range (4.0–12.0) and preferred alkaline environments. Interestingly, the enzymatic activity of TAPL7B was greatly activated by Ca2+ and it increased 9-fold in the presence of 1.2 mM Ca2+, which is rare in other alginate lyases. The activity of TAPL7B is not only activated by Ca2+, but also by some other metal ions (such as K+, Na+, Ni+, Cu2+, Mg2+, Zn2+, Co2+, Fe3+). The results of fast protein liquid chromatography (FPLC) and electrospray ionization mass spectrometry (ESI-MS) indicate that TAPL7B adopts an endo-action mode on all three substrates, and the products are all oligosaccharides with a degree of polymerization of 2–6. Therefore, the cold adaptability, broad pH stability, excellent metal ions stability, and Ca2+ activation of TAPL7B make it a potential industrial biocatalyst for the preparation of alginate oligosaccharides.

Strategic population responses of Daphnia spinulata Birabén, 1917 to salinity changes through laboratory bioassays

AbstractZooplankton play a key role in aquatic ecosystems constituting an essential intermediate component in aquatic food webs. Cladocerans in particular are widely studied as model of generalist filter feeders. At the regional level, the cladoceran Daphnia spinulata is found in numerous habitats with wide conductivity range (160 μS cm−1 to 14.000 μS cm−1), but information about the species's tolerance range or life history is scarce. Our objective was to generate essential information about D. spinulata's life history and the main parameters related to two contrasting salinity levels representative of water bodies of the pampean plain. Results obtained in laboratory bioassays showed that individuals at low conductivity (700 μS cm−1) had more moults, a lower mortality and a higher life expectancy at birth, a higher generation time, and an earlier peak density than those at high‐conductivity treatments (5000 μS cm−1). The maximum density reached was similar for both conductivities indicating a similar growth capability attained by different strategies. Moreover, the results indicated that D. spinulata at different conductivities was able to reproduce, with the offspring thus contributing to population growth. This study provided a knowledge of the life history strategies of this endemic cladoceran at two different conductivities, thus generating crucial information on the population dynamics and for evaluating the species's role as a possible salinity indicator in pampean water bodies. Nevertheless, future investigations will be necessary in order to identify the absolute limits of tolerance and the optimum conductivity for this species and determinate which stressors will act as a mictic stimuli.