The Research of Maneuverability Modeling and Environmental Monitoring Based on a Robotic Dolphin

In this study, the C-turning, pitching, and flapping propulsion of a robotic dolphin during locomotion were explored. Considering the swimming action required of a three-dimensional (3D) robotic dolphin in the ocean, we propose a maneuverability model that can be applied to the flapping motion to provide precise and stable movements and function as the driving role in locomotion. Additionally, an added tail joint allows for the turning movement with efficient parameters obtained by a fluid-structure coupling method. To obtain a mathematical model, several disturbance signals were considered, including systematic uncertainties of the parameters, the perpetually changing environment, the interference from obstacles with effective fuzzy rules, and a sliding mode of control. Furthermore, a combined strategy of environment recognition was used for the positional control of the robotic dolphin, incorporating sonar, path planning with an artificial potential field, and trajectory tracking. The simulation results show satisfactory performance of the 3D robotic dolphin with respect to flexible movement and trajectory tracking under the observed interference factors.

Self-Healable and Recyclable Biomass-Derived Polyurethane Networks through Carbon Dioxide Immobilization

Due to growing environmental issues, research on carbon dioxide (CO2) use is widely conducted and efforts are being made to produce useful materials from biomass-derived resources. However, polymer materials developed by a combined strategy (i.e., both CO2-immobilized and biomass-derived) are rare. In this study, we synthesized biomass-derived poly(carbonate-co-urethane) (PCU) networks using CO2-immobilized furan carbonate diols (FCDs) via an ecofriendly method. The synthesis of FCDs was performed by directly introducing CO2 into a biomass-derived 2,5-bis(hydroxymethyl)furan. Using mechanochemical synthesis (ball-milling), the PCU networks were effortlessly prepared from FCDs, erythritol, and diisocyanate, which were then hot-pressed into films. The thermal and thermomechanical properties of the PCU networks were thoroughly characterized by thermogravimetric analysis, differential scanning calorimetry, dynamic (thermal) mechanical analysis, and using a rheometer. The self-healing and recyclable properties of the PCU films were successfully demonstrated using dynamic covalent bonds. Interestingly, transcarbamoylation (urethane exchange) occurred preferentially as opposed to transcarbonation (carbonate exchange). We believe our approach presents an efficient means for producing sustainable polyurethane copolymers using biomass-derived and CO2-immobilized diols.

Potential for tourism to promote indigenous resources for community development in Musina Municipality, Vhembe District, Limpopo Province, South Africa

Purpose This study evaluates “potentials for using tourism in promoting indigenous resources for community development at Musina Municipality, Limpopo Province, South Africa.”Design/methodology/approach The study used a questionnaire survey, focus group discussions, and field observations to gather data. Microsoft Excel, Spreadsheet, cross-tabulation analysis, and manual sorting contributed to quantitative and qualitative data analyses.Findings The study uncovered vast significant indigenous species, resources, and tourism potentials with low impacts of indigenous species and resource benefits to the local communities. The details pointing to the actual and potential indigenous resources situations around tourism activities in Musina municipality emerged prominently. Thus, the study concluded such significant indigenous species, resources, and better tourism potentials need a well-combined strategy to channel the benefits to the local community's livelihoods.Originality/value The issue of indigenous resources, forests, trees, and tourism concerning rural community livelihoods has become of curiosity in the past few years. Nonetheless, few such studies have investigated the synergies between tourism and significant indigenous species and resources to improve their livelihoods.

Enhanced β-carotene and Biomass Production by Induced Mixotrophy in Dunaliella salina across a Combined Strategy of Glycerol, Salinity, and Light

Current mixotrophic culture systems for Dunaliella salina have technical limitations to achieve high growth and productivity. The purpose of this study was to optimize the mixotrophic conditions imposed by glycerol, light, and salinity that lead to the highest biomass and β-carotene yields in D. salina. The combination of 12.5 mM glycerol, 3.0 M salinity, and 50 μmol photons m−2 s−1 light intensity enabled significant assimilation of glycerol by D. salina and consequently enhanced growth (2.1 × 106 cell mL−1) and β-carotene accumulation (4.43 pg cell−1). The saline and light shock induced the assimilation of glycerol by this microalga. At last stage of growth, the increase in light intensity (300 μmol photons m−2 s−1) caused the β-carotene to reach values higher than 30 pg cell−1 and tripled the β-carotene values obtained from photoautotrophic cultures using the same light intensity. Increasing the salt concentration from 1.5 to 3.0 M NaCl (non-isosmotic salinity) produced higher growth and microalgal β-carotene than the isosmotic salinity 3.0 M NaCl. The mixotrophic strategy developed in this work is evidenced in the metabolic capability of D. salina to use both photosynthesis and organic carbon, viz., glycerol that leads to higher biomass and β-carotene productivity than that of an either phototrophic or heterotrophic process alone. The findings provide insights into the key role of exogenous glycerol with a strategic combination of salinity and light, which evidenced unknown roles of this polyol other than that in osmoregulation, mainly on the growth, pigment accumulation, and carotenogenesis of D. salina.

Production of 9,21-dihydroxy-20-methyl-pregna-4-en-3-one from phytosterols in Mycobacterium neoaurum by modifying multiple genes and improving the intracellular environment

Background Steroid drugs are essential for disease prevention and clinical treatment. However, due to intricated steroid structure, traditional chemical methods are rarely implemented into the whole synthetic process for generating steroid intermediates. Novel steroid drug precursors and their ideal bacterial strains for industrial production have yet to be developed. Among these, 9,21-dihydroxy-20-methyl-pregna-4-en-3-one (9-OH-4-HP) is a novel steroid drug precursor, suitable for the synthesis of corticosteroids. In this study, a combined strategy of blocking Δ1-dehydrogenation and the C19 pathway as well as improving the intracellular environment was investigated to construct an effective 9-OH-4-HP-producing strain. Results The Δ1-dehydrogenation-deficient strain of wild-type Mycobacterium neoaurum DSM 44074 produces 9-OH-4-HP with a molar yield of 4.8%. Hsd4A, encoding a β-hydroxyacyl-CoA dehydrogenase, and fadA5, encoding an acyl-CoA thiolase, were separately knocked out to block the C19 pathway in the Δ1-dehydrogenation-deficient strain. The two engineered strains were able to accumulate 0.59 g L−1 and 0.47 g L−1 9-OH-4-HP from 1 g L−1 phytosterols, respectively. Furthermore, hsd4A and fadA5 were knocked out simultaneously in the Δ1-dehydrogenation-deficient strain. The 9-OH-4-HP production from the Hsd4A and FadA5 deficient strain was 11.9% higher than that of the Hsd4A deficient strain and 40.4% higher than that of the strain with FadA5 deficiency strain, respectively. The purity of 9-OH-4-HP obtained from the Hsd4A and FadA5 deficient strain has reached 94.9%. Subsequently, the catalase katE from Mycobacterium neoaurum and an NADH oxidase, nox, from Bacillus subtilis were overexpressed to improve the intracellular environment, leading to a higher 9-OH-4-HP production. Ultimately, 9-OH-4-HP production reached 3.58 g L−1 from 5 g L−1 phytosterols, and the purity of 9-OH-4-HP improved to 97%. The final 9-OH-4-HP production strain showed the best molar yield of 85.5%, compared with the previous reported strain with 30% molar yield of 9-OH-4-HP. Conclusion KstD, Hsd4A, and FadA5 are key enzymes for phytosterol side-chain degradation in the C19 pathway. Double deletion of hsd4A and fadA5 contributes to the blockage of the C19 pathway. Improving the intracellular environment of Mycobacterium neoaurum during phytosterol bioconversion could accelerate the conversion process and enhance the productivity of target sterol derivatives.

Experience of Combined Procedure During Percutaneous Left Atrial Appendage Closure.

Introduction: Percutaneous left atrial appendage closure (LAAC) is an alternative to oral anticoagulant (OAC) in patients with non-valvular atrial fibrillation (AF) and contraindication to long-term OAC. Combined strategy with percutaneous LAAC at the same time of other cardiac structural or electrophysiological procedure has emerged as an alternative to staged strategy. Aim: To describe our experience of combined LAAC procedures using Watchman™ devices. Method: All patients with combined LAAC procedure using Watchman™ (WN) devices performed from 2016-2021 were included. The primary safety endpoint was a composite of periprocedural complications and adverse events during follow-up. The primary efficacy endpoint included strokes, systemic embolisms, major bleeding, and cardiovascular death. Results: Since 2016, among the 157 patients who underwent LAAC using WN devices, 16 underwent a combined strategy: 6 TEMVR (37%), 6 typical atrial flutter ablation (37%), 2 LP implantation (13%) and 2 atrial fibrillation ablation (13%). The WN device was successfully implanted in 98% and 100% for single and combined LAAC respectively (p = 0.63). Median follow-up was 13 months (IQR 25/75 3/24) in the whole cohort. Device related complications occurred in 6 out of 141 patients (4%) who underwent single LAAC and in no (0/16) patient in the combined LAAC procedure (p=ns). The procedural related complications did not differ significantly between groups (5% vs 12%, respectively in the single and combined group, p=0.1). Conclusion: Combined procedure combining LAAC using the Watchman™ devices and one other structural or electrophysiological procedure is safe and effective. Larger series are needed to confirm these results.

Adapted Reuse of Cultural Heritage & Atmosphere-Making in Lingnan Impression Park

In this article Lingnan Impression Park is taken as case study to research on integrated strategies of cultural heritage conservation with the purpose of its adapted reuse. In process exploitation, a combined strategy reusing architecture heritage is adopted, to produce an atmosphere of traditional Lingnan (Cantonese) culture for tourism development. This strategy has advantages for material recycle, construction energy saving and environmental protection, but arising an issue concerning heritage’s authenticity. It is regarded that it must be adopted a cultural ecology’s views to deal with the concept of authenticity especially in circumstance of heritage reuse with tourism exploitation.

A Combined Strategy of Improved Variable Selection and Ensemble Algorithm to Map the Growing Stem Volume of Planted Coniferous Forest

Remote sensing technology is becoming mainstream for mapping the growing stem volume (GSV) and overcoming the shortage of traditional labor-consumed approaches. Naturally, the GSV estimation accuracy utilizing remote sensing imagery is highly related to the variable selection methods and algorithms. Thus, to reduce the uncertainty caused by variables and models, this paper proposes a combined strategy involving improved variable selection with the collinearity test and the secondary ensemble algorithm to obtain the optimally combined variables and extract a reliable GSV from several base models. Our study extracted four types of alternative variables from the Sentinel-1A and Sentinel-2A image datasets, including vegetation indices, spectral reflectance variables, backscattering coefficients, and texture features. Then, an improved variable selection criterion with the collinearity test was developed and evaluated based on machine learning algorithms (classification and regression trees (CART), k-nearest neighbors (KNN), support vector regression (SVR), and artificial neural network (ANN)) considering the correlation between variables and GSV (with random forest (RF), distance correlation coefficient (DC), maximal information coefficient (MIC), and Pearson correlation coefficient (PCC) as evaluation metrics), and the collinearity among the variables. Additionally, we proposed a secondary ensemble with an improved weighted average approach (IWA) to estimate the reliable forest GSV using the first ensemble models constructed by Bagging and AdaBoost. The experimental results demonstrated that the proposed variable selection criterion efficiently obtained the optimal combined variable set without affecting the forest GSV mapping accuracy. Specifically, considering the first ensemble, the relative root mean square error (rRMSE) values ranged from 21.91% to 30.28% for Bagging and 23.33% to 31.49% for AdaBoost, respectively. After the secondary ensemble involving the IWA, the rRMSE values ranged from 18.89% to 21.34%. Furthermore, the variance of the GSV mapped by the secondary ensemble with various ranking methods was significantly reduced. The results prove that the proposed combined strategy has great potential to reduce the GSV mapping uncertainty imposed by current variable selection approaches and algorithms.