Characterization of the surface-active exopolysaccharide produced by Halomonas sp TGOS-10: understanding its role in the formation of marine oil snow

In this study, we characterize the exopolymer produced by Halomonas sp. strain TGOS-10 ¬– one of the organisms found enriched in sea surface oil slicks during the Deepwater Horizon oil spill. The polymer was produced during the early stationary phase of growth in Zobell’s 2216 marine medium amended with glucose. Chemical and proton NMR analysis showed it to be a relatively monodisperse, high-molecular-mass (6,440,000 g/mol) glycoprotein composed largely of protein (46.6% of total dry weight of polymer). The monosaccharide composition of the polymer is typical to that of other marine bacterial exopolymers which are generally rich in hexoses, with the notable exception that it contained mannose (commonly found in yeast) as a major monosaccharide. The polymer was found to act as an oil dispersant based on its ability to effectively emulsify pure and complex oils into stable oil emulsions – a function we suspect to be conferred by the high protein content and high ratio of total hydrophobic nonpolar to polar amino acids (52.7:11.2) of the polymer. The polymer's chemical composition, which is akin to that of other marine exopolymers also having a high protein-to-carbohydrate (P/C) content, and which have been shown to effect the rapid and non-ionic aggregation of marine gels, appears indicative of effecting marine oil snow (MOS) formation. We previously reported the strain capable of utilising aromatic hydrocarbons when supplied as single carbon sources. However, here we did not detect biodegradation of these chemicals within a complex (surrogate Macondo) oil, suggesting that the observed enrichment of this organism during the Deepwater Horizon spill may be explained by factors related to substrate availability and competition within the complex and dynamic microbial communities that were continuously evolving during that spill

Combined fluorescence lifetime and surface topographical imaging of biological tissue

In this work a combined fluorescence lifetime and surface topographical imaging system is demonstrated. Based around a 126 × 192 time resolved single photon avalanche diode (SPAD) array operating in time correlated single-photon counting (TCSPC) mode, both the fluorescence lifetime and time of flight (ToF) can be calculated on a pixel by pixel basis. Initial tests on fluorescent samples show it is able to provide 4 mm resolution in distance and 0.4 ns resolution in lifetime. This combined modality has potential biomedical applications such as surgical guidance, endoscopy, and diagnostic imaging. The system is demonstrated on both ovine and human pulmonary tissue samples, where it offers excellent fluorescence lifetime contrast whilst also giving a measure of the distance to the sample surface

Designing hydrogen-free diamond like multilayer carbon coatings for superior mechanical and tribological performance

Diamond like carbon (DLC) coatings are extensively employed for their outstanding mechanical and tribological properties. To overcome the inherent high residual stress, therefore brittleness, DLC coatings with multilayer architecture were developed in the form of stacking alternate hard and soft layers to avoid premature failure under severe loading conditions. The current study was designed to investigate the impact of bilayer thickness (hard & soft) on wear of multilayer DLC particularly at high contact stress (2.0 GPa, 2.7 GPa, 3.0 GPa, 3.4 GPa). Seven DLC multilayer (1:1 bilayer ratio) samples with 1, 2, 5, 10, 20, 40, 80 bilayers were deposited on 440 C steel and the overall coating thickness was mainatined at ~1 µm. Moreover, the bilayer thickness effect was determined on mechanical, scratch adhesion and structural properties. Transmission electron microscope (TEM) was used to visualize discrete hard and soft layers in 80 bilayers (~6 nm thin layer). G peak suppression and ID/IG increment were observed with reduction in bilayer thickness. Hardness, modulus, elastic strain to failure (H/E), plastic deformation resistance (H3/E2) and residual stresses showed an inverse relation with bilayer thickness. Furthermore, micro scratch adhesion decreases with layer thickness reduction. Only 100 nm and above bilayer thickness samples (1, 2, 5, 10 bilayers) could survive under high contact stress while the other three (20, 40, 80 bilayers) showed brittle failure using pin-on-disc tribometer. Additionally, 10 bilayers (100 nm thickness) produced the minimum wear (~7.9 ×10-8 mm3/Nm) at 80 N

Assessment of coffee-ring effect on wool and cotton fabrics inkjet printed with herbal inks

In this study, the ecologically pre-treated wool and cotton fabrics were digitally printed with eco-friendly plant-based inks of blue, red, yellow, and black colours obtained from the plant extracts of bio indigo leaves, quebracho red bark and the flame of the forest flowers and evaluated for coffee-ring effect. The plant-based inks constituted from the Quebracho red bark and the flame of the forest flowers extract both demonstrated reduced dispersion diameter (i.e. diffused) for the Plasma Surface Treated (PST) wool and cotton fabric than the untreated. These findings could be applied for digital printing on photonics to combat the Coffee-ring effect. The possible explanation for the reduced coffee ring effect is the phenomenon known as Marangoni flow. The predominant phytochemicals functioning as chromophores namely indigotin, tannin and butein enclosed in inks constituted from the plant extracts of bio indigo leaves, quebracho red bark and the flame of the forest flowers respectively are highlighted. Additionally, the synthesis of plant-based ink, the colour scheme adapted for determining the inks colours, and the technique of print process as implemented in the study are explained. Likewise, the Colour patch, Percentage (%) Reflectance, and, Colour difference graphs as acquired from Datacolor tools are demonstrated. To end, the wash fastness, rub fastness, and light fastness test results obtained on wool and cotton fabrics digitally printed with innovative plant-based inks are detailed. The Life Cycle Analysis and assessment of functional phytochemicals on the resultant printed fabrics are suggested for future work

Intersecting Bonds: A Perspective on Polygamy's Influence in Arab Middle East Family Firm Succession

PurposeThe aim of this study is to explore and elucidate the influence of polygamy on the succession dynamics of family businesses in the Arab world, offering insights that may be underrepresented or overlooked in traditional, Western-focused literature.Design/methodology/approachThis article adopts a perspective-based approach, focusing on delving into the amalgamation of polygamous family structures and their implications on the operation and continuation of family-run businesses.FindingsPolygamy, while often primarily perceived as a cultural or religious tradition, wields substantial influence over various business facets. Notably, its presence can significantly shape business continuity, the methodologies behind succession planning and the overarching framework of corporate governance within Arab family businesses.Originality/valueThis article offers a unique Middle Eastern lens, highlighting the underexplored intersection of polygamy and business succession. It strives to bridge the knowledge gap by addressing topics potentially sidelined in mainstream Western business research

Delineating the boundaries between genuine cultural change and cultural appropriation in majority-group acculturation

An emerging literature has begun to explore the acculturation of majority-group members within increasingly diverse societies. Given the inherent power asymmetries and ethnic hierarchies that usually favor majority groups, it becomes critical to examine their acculturation process through the lens of power dynamics. Central to this examination is determining when a majority group’s adoption of cultures from other groups (e.g., ethnocultural minorities who are indigenous or have a history of forced or voluntary migration) constitutes cultural appropriation versus genuine cultural change. In this paper, we argue that cultural appropriation becomes evident when majority-group members exploit cultural elements from less powerful ethnic groups against their will, often for material or symbolic gains, without providing proper credit or demonstrating a deeper understanding of the culture. By contrast, genuine cultural change is distinguishable from appropriation when it is characterized by deep cultural learning (as opposed to cultural engagement that remains superficial), concerns other groups as equal, and is consented to by the group whose culture is being adopted. Existing acculturation research suggests that the cultural adoption by majority-group members is typically driven more by self-reported egalitarian motives than by a desire for dominance, and that minority groups do not principally object to this adoption. Therefore, it is improbable that all aspects of majority-group members’ cultural adoption would constitute cultural appropriation. However, further research is needed to empirically differentiate cultural appropriation from genuine forms of cultural change within majority groups, particularly by investigating the perspectives of the groups whose cultures are being adopted

Mechanical behaviour and experimental evaluation of self-centring steel plate shear walls considering frame-expansion effects

The rocking mechanism of self-centring connections can lead to frame expansion, which can cause significant deformation demands on structural members, incompatible displacements among different structural systems, and excessive cracks in concrete slabs. To address this issue, this study proposes a mixed dual lateral force-resisting system composed of a high strength moment-resisting steel frame (HS-MRF) and self-centring steel plate shear walls (SC-SPSWs). The independent response of SC-SPSWs allows for gap formation without interfering with HS-MRF, thus enabling the use of continuous slabs. The paper first discusses a conceptual damage-control design that includes four performance levels, followed by a mechanical and experimental investigation to study the relationships among structural elements and overall responses, energy-dissipating capability, connection response, post-tensioned (PT) element behaviour, and structural repair potential. The results indicate that the proposed analytical model can reasonably predict the force responses of SC-SPSW with rocking bases. The tested frame exhibited stable flag-shaped hysteretic behaviour with no collapse up to 5.0% inter-storey drift. The web plates served as easy-to-replace energy-dissipating elements, and residual drifts remained small, implying that the proposed structure can be repaired easily in the aftermath of a strong seismic event. Rocking behaviour was observed in both beam-to-column connections and column bases. Although frame expansion still occurs and increases the axial force in the beams of the first storey, the main structural elements can be designed to remain elastic.</p

Mechanical behaviour and experimental evaluation of self-centring steel plate shear walls considering frame-expansion effects

The rocking mechanism of self-centring connections can lead to frame expansion, which can cause significant deformation demands on structural members, incompatible displacements among different structural systems, and excessive cracks in concrete slabs. To address this issue, this study proposes a mixed dual lateral force-resisting system composed of a high strength moment-resisting steel frame (HS-MRF) and self-centring steel plate shear walls (SC-SPSWs). The independent response of SC-SPSWs allows for gap formation without interfering with HS-MRF, thus enabling the use of continuous slabs. The paper first discusses a conceptual damage-control design that includes four performance levels, followed by a mechanical and experimental investigation to study the relationships among structural elements and overall responses, energy-dissipating capability, connection response, post-tensioned (PT) element behaviour, and structural repair potential. The results indicate that the proposed analytical model can reasonably predict the force responses of SC-SPSW with rocking bases. The tested frame exhibited stable flag-shaped hysteretic behaviour with no collapse up to 5.0% inter-storey drift. The web plates served as easy-to-replace energy-dissipating elements, and residual drifts remained small, implying that the proposed structure can be repaired easily in the aftermath of a strong seismic event. Rocking behaviour was observed in both beam-to-column connections and column bases. Although frame expansion still occurs and increases the axial force in the beams of the first storey, the main structural elements can be designed to remain elastic.</p