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Being interested in developing a natural preservative for the prolongation of shrimp shelf life, this study aims to evaluate the Sargassum horneri extracts for their antioxidant effect, copper reducing power, copper chelating activity and polyphenol oxidase (PPO) inhibitory activity, as well as explored their potential preservative activity in white leg shrimp.

The antioxidant properties of Sargassum horneri 75% ethanol aqueous extracts were measured by 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and PPO inhibitory activity. Sample III displayed the highest antioxidant activity, PPO inhibitory activity, copper reducing power and copper chelating activity, so it was selected for further studying its impact on shrimp's quality changes such as pH value, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), melanosis and sensory score during storage at 4°C.

Among all three samples, sample III containing 49.88% total phenolic contents was selected for the further study on the prevention of quality loss and melanosis of shrimp, because it yielded the highest antioxidant activity, PPO inhibitory activity, copper reducing power and copper chelating activity than the other two samples (samples II and IV). It was found that shrimp treated with 0.2% sample III had the lowest melanosis scores throughout the storage (p < 0.05). During ten days of storage at 4°C, shrimp treated with 0.2% sample III had a higher score in sensory properties (color, segments, texture and odor), compared with the control, 0.1% kojic acid and 0.1% sample III treated shrimp (p < 0.05). The results indicated that the treatment of shrimp with 0.2% sample III could extend the shelf life to eight days at 4°C.

The extracts of Sargassum horneri displayed potent PPO inhibition, antimicrobial and antioxidant properties. Importantly, the 75% extracts of Sargassum horneri could extend the shelf life. Considering these results, the extracts of Sargassum horneri may be used as natural preservatives in the food industry after further evaluation of their other properties such as toxicity, as well as provide a choice target to source natural products intended for cosmetics.

The originality of this paper lies in the development and application of the extracts of edible algae. To extend the shelf life of seafood, the polyphenolic-rich extract of Sargassum horneri provided another possible selection.

The purpose of this paper is to investigate how absorptive capacity mediates the relationship between ambidextrous organizational learning and performance among small and medium-sized enterprises (SMEs).

Based on the resource-based view (RBV) and the dynamic capability approach, this paper uses the resource-capability-performance framework to construct the theoretical model of this study and tests the theoretical model with the questionnaire survey data of 189 SMEs in mainland China.

Ambidextrous organizational learning has different effects on SMEs' performance in terms of survival performance and growth performance. Both exploitative learning and exploratory learning have positive effects on absorptive capacity, and absorptive capacity has positive influences on both the survival performance and growth performance of SMEs. Absorptive capacity plays different mediating roles in the relationships between ambidextrous organizational learning and SMEs' performance: absorptive capacity plays a partial mediating role in the relationship between exploratory learning and SME growth performance, while absorptive capacity plays complete mediating roles in other relationships.

Managers must stress the use of exploratory learning in order to promote SMEs' growth performance. However, to foster both absorptive capacity and SME performance in terms of survival and growth, managers must pay more attention to take advantage of ambidextrous organizational learning. Government as policymakers should create a favorable environment that enable SMEs to benefit much more from the deployment of ambidextrous organizational learning and absorptive capacity.

To the best of authors’ knowledge, this study is the first to theorize and test the mediating role of absorptive capacity in the linkage between ambidextrous organizational learning and SME performance in terms of survival and growth. Additionally, this study also is the first to provide empirical support for the impact of ambidextrous organizational learning on absorptive capacity among SMEs.

The purpose of the paper is to introduce the dynamic phasor modelling (DPM) approach for stability investigation and control design of single-phase phase-locked loops (PLLs). The aim is to identify the system instabilities not predicted using the existent analysis and design methods based on the simplified average model approach.

This paper starts by investigating the performance of three commonly used PLL schemes: the inverse park-PLL, the second-order generalised integrators (SOGI)-frequency-locked loop and the enhanced-PLL, designed using the simplified average model and will show that following this approach, there is a mismatch between their actual and desired transient performance. A new PLL design method is then proposed based on the DPM approach that allows the development of fourth-order DPM models. The small-signal eigenvalues analysis of the fourth-order DPM models is used to determine the control gains and the stability limits.

The DPM approach is proven to be useful for single-phase PLLs stability analysis and control parameters design. It has been successfully used to design the control parameters and to predict the PLL stability limits, which have been validated via simulation and experimental tests consisting of grid voltage sag, phase jump and frequency step change.

This paper has introduced the use of DPM approach for the purpose of single-phase PLL stability analysis and control design. The approach has enabled accurate control gains design and stability limits identification of single-phase PLLs.