Effect of rhamnolipids biosurfactant on traditional surfactants: A macro- and microrheological study

The global surfactant market is expected to reach $44.9 billion by 2022, of which 67% of the demand is from the personal care and detergents market [1]. Due to consumers’ increasing awareness on product sustainability, the microbially produced biosurfactants are increasingly gaining the interest of the personal care industry as potential alternatives for traditional petroleum derived and chemically synthesized surfactants [2]. The future of personal care and detergent products is the elimination of non-biodegradable, environmentally toxic surfactants. However, prior to that, an understanding of how performance criteria such as rheology is affected by substitution of traditional surfactants with biosurfactants is required. In this study, the affect of rhamnolipid biosurfactant on the rheological response of traditional surfactants such as sodium laureth sulfate and cocamidopropyl betaine is explored utilizing mechanical rheometry, microrheometry, microfluidic rheometry and Raman spectroscopy. The study provides unique insights into microstructure-rheology linkages in complex biosurfactant-surfactant mixtures. Reference [1] News & Views - Market Reports: Global Markets for Surfactant Chemicals and Materials. Chemical Industry Digest. 2018. ISSN: 0971-5266. [2] Fakruddin Md (2012) Biosurfactant: Production and Application. J Pet Environ Biotechnol 3:124. doi:10.4172/2157-7463.1000124 *L.Xu and Y.Zhou contributed equally to this work

The aerodynamic and structural study of flapping wing vehicles

This thesis reports on the aerodynamic and structural study carried out on flapping wings and flapping vehicles. Theoretical and experimental investigation of aerodynamic forces acting on flapping wings in simple harmonic oscillations is undertaken in order to help conduct and optimize the aerodynamic and structural design of flapping wing vehicles. The research is focused on the large scale ornithopter design of similar size and configuration to a hang glider. By means of Theodorsen’s theory the aerodynamic forces on a thin aerofoil subject to heaving, pitching, and combined heaving and pitching motions are carefully studied. The analytical method is then employed to calculate the lift acting on the rigid flat plate undergoing small simple harmonic oscillations at different airspeeds and frequencies. The theoretical calculations are compared with experimental results which show reasonably good agreement. However experimental study shows that the wing frame deformation induces extra aerodynamic forces which can change the overall wing performance. Hence an experimental investigation focusing on wing flexibility effect on aerodynamic forces is also carried out. Three wings of similar planform geometry but slightly different degree of flexibility are manufactured for wind tunnel testing. Test results show that the wing deformation not only affects the aerodynamic forces but also the required power for various wing flapping motions. By understanding the aerodynamic performance of flapping wings from both theoretical and experimental studies the preliminary design of large scale ornithopter is carried out based on a hang glider prototype. Theoretical and experimental studies are carried out to validate aerodynamically the loading acting on the wing and finite element analysis is carried out to evaluate the structural strength. In addition, DeLaurier’s method is employed to calculate the aerodynamic forces of flapping wings by taking into account of the wing aspect ratio. The test results show good agreement with the theoretical calculation by DeLaurier’s method. However the FEA results indicate structural failure based on the original calculation by assuming the wing is completely rigid. Modification of aerodynamic modelling is carried out to reassess the structural strength by taking into account of the wing deformation and possible effect due to large angle of attack which shows a much more reasonable stress distribution on the entire wing structure without failure. Furthermore three wing planform and structural modifications are carried out to improve the aerodynamic performance of the flapping wing. Finally the folding wing design case is selected as the optimal design which produces the highest overall positive lift and a variable geometric system is employed to control the folding motion of the wing

Effect of rhamnolipids on surface tension and interfacial behaviors on traditional surfactants

The global surfactant market is expected to reach $44.9 billion by 2022, of which 67% of the demand is from the personal care and detergents market [1]. Due to consumers’ increasing awareness on product sustainability, the microbial-produced biosurfactants are increasingly gaining the interest of the personal care industry as potential alternatives for traditional petroleum-derived and chemically synthesized surfactants [2]. The future of personal care and detergent products is the elimination of non-biodegradable, environmentally toxic surfactants. However, prior to that, an understanding of performance criteria such as surface tension is affected by substitution of traditional surfactants with biosurfactants is required. This study mainly focuses on the influences of rhamnolipid biosurfactant on surface tensions and CMC behavior of sodium laureth sulfate and cocamidopropyl betaine. In addition, the effect of rhamnolipids on the interfacial tensions of surfactants mixture and dimethicone have also been evaluated. Reference [1] News & Views - Market Reports: Global Markets for Surfactant Chemicals and Materials. Chemical Industry Digest. 2018. ISSN: 0971-5266. [2] Fakruddin Md (2012) Biosurfactant: Production and Application. J Pet Environ Biotechnol 3:124. doi:10.4172/2157-7463.1000124 * Y.Zhou and L.Xu contributed equally to this work

Pollution level and risk assessment of heavy metals in sewage sludge from eight wastewater treatment plants in Wuhu City, China

Aim of study: To investigate the content, contamination levels and potential sources of five heavy metals (Hg, Pb, Cd, Cr, As) in sewage sludge from eight wastewater treatment plants (W1 to W8).Area of study: Wuhu, located in southeastern Anhui Province, southeastern China.Material and methods: The sewage sludge pollution assessment employed the single-factor pollution index, Nemerow’s synthetic pollution index, monomial potential ecological risk coefficient and potential ecological risk index. The potential sources among the five heavy metals were determined using the Pearson’s correlation analysis and principal component analysis (PCA).Main results: The mean concentrations of the heavy metals were 0.27 mg/kg (Hg), 70.78 mg/kg (Pb), 3.48 mg/kg (Cd), 143.65 mg/kg (Cr) and 22.17 mg/kg (As). W1, W5 and W6 sewage sludge samples showed the highest levels of heavy metal contamination, and cadmium had the highest contamination level in the study area. Pearson’s correlation analysis and PCA revealed that Pb and Cd mainly derived from traffic emissions and the manufacturing industry and that As and Cr originated from agricultural discharges.Research highlights: The pollution of cadmium in Wuhu should be controlled preferentially. The heavy metal pollution of W1, W5 and W6 sewage treatment plants is relatively high, they should be key prevention targets

Gradient constrained sharpness-aware prompt learning for vision-language models

This paper targets a novel trade-off problem in generalizable prompt learning for vision-language models (VLM), i.e., improving the performance on unseen classes while maintaining the performance on seen classes. Comparing with existing generalizable methods that neglect the seen classes degradation, the setting of this problem is more strict and fits more closely with practical applications. To solve this problem, we start from the optimization perspective, and leverage the relationship between loss landscape geometry and model generalization ability. By analyzing the loss landscapes of the state-of-the-art method and vanilla Sharpness-aware Minimization (SAM) based method, we conclude that the trade-off performance correlates to both loss value and loss sharpness, while each of them is indispensable. However, we find the optimizing gradient of existing methods cannot maintain high relevance to both loss value and loss sharpness during optimization, which severely affects their trade-off performance. To this end, we propose a novel SAM-based method for prompt learning, denoted as Gradient Constrained Sharpness-aware Context Optimization (GCSCoOp), to dynamically constrain the optimizing gradient, thus achieving above two-fold optimization objective simultaneously. Extensive experiments verify the effectiveness of GCSCoOp in the trade-off problem.Comment: 19 pages 11 figure

Improving fermentative hydrogen and methane production from an algal bloom through hydrothermal/steam acid pretreatment

Algal blooms can be harvested as renewable biomass waste for gaseous biofuel production. However, the rigid cell structure of raw algae may hinder efficient microbial conversion for production of biohydrogen and biomethane. To improve the energy conversion efficiency, biomass from an algal bloom in Dianchi Lake was subjected to a hydrothermal/steam acid pretreatment prior to sequential dark hydrogen fermentation and anaerobic digestion. Results from X-ray diffraction and Fourier transform infrared spectroscopy suggest that hydrothermal acid pretreatment leads to stronger damage of the amorphous structure (including hemicellulose and amorphous cellulose) due to the acid pretreatment, as evidenced by the higher crystallinity index. Scanning electron microscopy analysis showed that smaller fragments (∼5 mm) and wider cell gaps (∼1 μm) on algal cell surfaces occurred after pretreatment. In comparison to steam acid pretreatment, hydrothermal acid pretreatment resulted in a maximum energy conversion efficiency of 44.1% as well as production of 24.96 mL H2/g total volatile solids (TVS) and 299.88 mL CH4/g TVS

Chapter 13:Polymer Colloids for Cosmetics and Personal Care

Polymer colloids have been utilized in the cosmetics and personal care industrial sector for the last several decades. They exhibit unique rheological, tribological, optical, and film-forming properties that make them highly appealing for incorporation into cosmetic products. Of these properties, film formation plays one of the most critical roles for their performance in cosmetics. This is utilized in optimizing performance of makeup products like foundation, mascara, nail polish, and lipstick. Their superior lubrication performance allows the generation of distinctive sensory responses from skin care and makeup products. Recent advances in smart polymer colloids has allow the further adoption of these materials into next-generation cosmetics through engineering specific stimuli-responsive changes in rheology, tribology, and optical performance. This chapter discusses both the fundamental performance-controlling properties of polymer colloids and how these are utilized in developing and optimizing a wide range of cosmetics and personal care products