Circular Pathway Research Articles

A circular pathway for developing resilience in healthcare during pandemics

In the last few years, the studies on supply chain resilience have increased dramatically also due to the need to face the COVID-19 pandemic. However, although resilience has been studied in many fields, there is still a lack of in-depth understanding of how supply chains can develop resilience in healthcare. To contribute to this research gap, empirical data were gathered from nine fine-grained case studies belonging to the first European country affected by COVID-19, i.e., Italy.Adopting the dynamic capability theory, the research contributes to theory with the conceptualization of the circular pathway and two theoretical propositions that support the understanding of how resilience is developed in healthcare during pandemics. Finally, the paper contributes to practice with the definition of 12 dynamic capabilities and relevant insights about the activities, practices and elements required to develop resilience during disruptive events, like pandemics. These results support practitioners in planning the future development of resilience in healthcare.

The CIRCULAR pathway: a new educational methodology for exploratory circular value chain redesign

The circular economy (CE) is gaining global relevance across countries and institutions as a tool to solve some of the most pressing global challenges derived from linear production and consumption systems. However, transitioning to a CE requires significant changes in how businesses and supply chains operate, including redesigning products, processes, and business models. These changes require that future professionals acquire knowledge and skills on the principles of CE, Life Cycle Thinking, and Systems Thinking. However, research on existing higher education programs signals a need for educational resources to develop these skills and knowledge in real-world settings. This paper outlines a new eight-step methodology to introduce students to the principles of CE through the exploratory redesign of a real-world product and value chain in a project-centered learning environment. This methodology was developed in four iterations and was used to teach 251 students from the BSc. Business Engineering at Maastricht University during the academic years 2020–2022. The findings indicate that this method supports students' understanding of complexity, linearity, and the importance of systemic change across the entire value chain, as well as their critical thinking, problem-solving, and decision-making skills. The methodology provided in this paper supports and encourages educational bodies to implement Education for CE in their curricula and further strengthens the complementary fields of Education for Environmental Sustainability and Education for Sustainable Development. Furthermore, educators, professionals and businesses can make use of this tested methodology for exploratory product redesign toward sustainable circularity transitions.

Evolution of livelihood vulnerability in rice terrace systems: Evidence from households in the Ziquejie terrace system in China

IntroductionGlobally, terraces, and rice terrace systems face problems that affect their sustainability, such as terrace degradation, abandonment, de-agriculturalization, labor migration, etc. The implementation of development projects such as reforestation, poverty alleviation, and tourism development have changed traditional smallholder livelihood patterns. It is not clear whether farmers' livelihoods have become more resilient or vulnerable as a result.MethodsUsing survey data on households' livelihoods in a rice terrace system in Southern China, we evaluated the livelihood impacts of multiple changes.ResultsThe results show that development projects are not entirely beneficial. The attributes and intensity of the disturbance of projects (e.g., tourism) on land functions, and differentiated farmer strategies jointly drive the hierarchical evolution of livelihood vulnerability. In detail, underdeveloped tourism increased rather than reduced livelihood vulnerability; the role of agriculture in livelihood directly exacerbated the variation in vulnerability levels; this resulted in the most vulnerable livelihood for households that are exogenously dependent or located in the core tourism area.DiscussionSubsequently, an evolutionary model of livelihood vulnerability is proposed in this study. Based on this, we judged that the livelihood vulnerability of rice terrace systems has entered a chaotic stage of adaptation. Reducing livelihood vulnerability will require the support of a tangible and circular pathway of benefits between farmers and the land. Policies should focus on the heterogeneity of farmers and the “negative effects” of development projects on livelihood. This household-level farmer livelihood vulnerability dynamics study goes beyond anti-poverty to provide science-based practical guidance to promote the sustainable development of rice terrace systems.

Potential of Earth-Based Bamboo Bio-Concrete in the Search for Circular and Net-Zero Carbon Solutions to Construction Industry

In order to limit climate change by achieving goals of cutting emissions down to net-zero by 2050, stronger efforts are needed to reduce the whole life cycle emissions of buildings. Integrating residual bio-based and earth-based solutions to concrete seems to stand out in the sector since these solutions have the potential of lowering materials embodied emissions, and enhancing building thermal performance. However, it is still unclear how environmentally beneficial bio-based and earth-based materials are and how they behave mechanically when they are both integrated into concrete. In order to know their potential applications in the sector, this study aims to evaluate and compare the mechanical performance and environmental profile of Earth-based Bamboo Bio-Concretes (EBBCs) with different earth fractions as partial replacements of the cementitious matrix, by evaluating its Greenhouse Gas (GHG) emissions. For that, it was considered the use of only bio-based aggregates (bamboo waste) instead of mineral ones at a fixed volume fraction of 45%. The methodology involved the: processing and characterization of earth and bamboo; EBBCs dosage study and mechanical testing; consideration of fixed proportions of binders of 30:30:40 (cement: metakaolin: fly ash) which were replaced gradually by earth in the volume fractions of 10%, 15%, and 20%. The Life Cycle Assessment (LCA) was used for accounting GHG emissions. LCA scope was from cradle-to-gate considering biogenic carbon methodology and avoided impacts of incinerating bamboo waste. A sensitive analysis was performed to evaluate the impact of transport distances variation of bamboo waste. Mechanical results point to an increase in EBBCs compressive strength with the increase of earth content until 15% of cementitious matrix replacement. LCA results showed negative embodied GHG emissions in all mixtures with an average of -115,7 kgCO2-eq/m3 mainly due to the high biomass content in mixtures. The increase of earth content from 0% to 20% in the mixtures reduced emissions by 59,7 kgCO2-eq/m3 since the binder’s content was reduced. With that, EBBC seems to be a promising innovative material to help achieve net-zero carbon emission targets and a circular pathway in the building and construction sectors.

Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework.

Increasing levels of air pollution are driving the need for the development of new processes that take “waste-to-chemicals”. Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO2, using a robust metal-organic framework (MOF) material, Zr-bptc (H4bptc = 3,3′,5,5′-biphenyltetracarboxylic acid), comprising {Zr6(μ3-O)4(μ3-OH)4(COO)12} clusters linked by 4-connected bptc4– ligands in an ftw topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO2 at both low (4.9 mmol g–1 at 10 mbar) and high pressures (13.8 mmol g–1 at 1.0 bar), as measured by isotherm experiments. Dynamic breakthrough experiments have confirmed the selective retention of NO2 by Zr-bptc at low concentrations under both dry and wet conditions. The immobilized NO2 can be readily transformed into valuable nitro compounds relevant to construction, agrochemical, and pharmaceutical industries. In situ crystallographic and spectroscopic studies reveal strong binding interactions of NO2 to the {Zr6(μ3-O)4(μ3-OH)4(COO)12} cluster node. This study paves a circular pathway to enable the integration of nitrogen-based air pollutants into the production of fine chemicals.

Performance assessment and life cycle analysis of concrete containing ferrochrome slag and fly ash as replacement materials – A circular approach

• Circular pathway through use of FCS aggregate and fly ash in concrete was explored. • An eco-efficient mix design method based on PPOT was adopted. • Ten types of concrete mixes were prepared using PPOT and conventional mix design. • The techno-environmental performance of all mixes were studied. • FCSAC with 30% fly ash designed by PPOT was ranked as the most sustainable mix. Climate change mitigation and resource efficiency have emerged as crucial challenges for long-term sustainability of concrete. Implementing circular approach through waste valorisation in concrete production with eco-efficient mix design is an efficient mitigation pathway to combat natural resources depletion and environmental issues. This paper investigates techno-environmental sustainability of concrete utilizing 100% ferrochrome slag as alternate coarse aggregate and fly ash as partial cement substitute (0–40%) adopting particle packing optimization technique (PPOT) as a sustainable mix design method. Total of ten types of concrete mixtures were prepared using the alternate materials and mix design methods (PPOT and IS:10262(2009)). Natural aggregate concrete prepared by IS:10262(2009) mix design was considered as the reference mixture. Technical assessment of concrete was performed experimentally in terms of compressive strength and tensile strength. Environmental performance was investigated through life cycle assessment (LCA) as per ISO 14040-44 guidelines using cradle-to-gate system boundary and two functional units: 1 m 3 concrete and 1 MPa compressive strength. Results revealed that ferrochrome slag aggregate concrete (FCSAC) containing fly ash up to 30% prepared by PPOT has enhanced strength than reference concrete. Regardless of the functional units used, FCSAC with 30% fly ash designed by PPOT was ranked as the most sustainable mix with significant environmental savings (around 50–70%) without compromising desired requirements. Sensitivity analysis was performed by varying transportation distance, mode of transport and energy mix. Results showed that FCSAC with 30% fly ash is not sensitive to the scenarios investigated. The outcomes will be helpful for decision-makers to develop policy directives and frameworks on synergistic use of ferrochrome slag and fly ash towards concrete sustainability.

Training of Faculty and Staff in Recognising Undergraduate Medical Students' Psychological Symptoms and Providing Support: A Narrative Literature Review.

Mental illness among medical students in particular, and higher education students in general, is very high. Many measures have been suggested in order to improve the situation, including training members of faculty and staff. However, to the best of our knowledge there seem to be no studies proposing training programmes for medical schools’ faculty and staff in response to recognising students’ psychological difficulties and symptoms in order to provide the relevant support. Also, in cases where such training for supporting medical students with psychological symptomatology exist, the efficacy of the approach employed is not known. By employing a careful literature search according to published guidelines for narrative literature reviews, this study aimed to fill in this identified gap in the literature. From the literature search, 14 articles were included in this review and the results show that no training tailored for faculty and staff in medical schools was identified. However, articles that related to higher education were included because they were useful in providing insights for medicine, and show the following: (a) faculty and staff acknowledged the importance of mental illness among students, (b) many of them discussed with their students psychological symptoms and provided support, (c) they tended to feel unprepared for recognising students’ psychological symptoms successfully and providing support, (d) they embraced the idea of being trained, and (e) any training seemed to be helpful for members of faculty and staff. From the results of this narrative review, we propose the CReATE circular pathway to ensure a sustainable process of training and support for students’ development.

Being silenced, loneliness and being heard: understanding pathways to intimate partner violence & abuse in young adults. a mixed-methods study

BackgroundInternational research shows the significance and impact of intimate partner violence and abuse (IPVA) as a public health issue for young adults. There is a lack of qualitative research exploring pathways to IPVA.MethodsThe current mixed-methods study used qualitative interviews and analysis of longitudinal cohort data, to explore experiences of pathways to IPVA. Semi-structured Interviews alongside Life History Calendars were undertaken to explore 17 young women’s (19–25 years) experiences and perceptions of pathways to IPVA in their relationships. Thematic analysis was undertaken.Based on themes identified in the qualitative analysis, quantitative analysis was conducted in data from 2127 female and 1145 male participants of the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort study. We fitted regression models to assess the association of child maltreatment, parental domestic violence, and peer-to-peer victimisation, by age 12, with loneliness during adolescence (ages 13–14), and the association of loneliness during adolescence with IPVA (age 18–21). Mediation analysis estimated the direct effects of maltreatment on IPVA, and indirect effects through loneliness.FindingsAll women interviewed experienced at least one type of maltreatment, parental domestic violence, or bullying during childhood. Nearly all experienced IPVA and most had been multi-victimised. Findings indicated a circular pathway: early trauma led to isolation and loneliness, negative labelling and being silenced through negative responses to help seeking, leading to increased experiences of loneliness and intensifying vulnerability to further violence and abuse in young adulthood. The pathway was compounded by intersectionality. Potential ways to break this cycle of loneliness included being heard and supported, especially by teachers.Quantitative analysis confirmed an association between child maltreatment and loneliness in adolescence, and an association between loneliness in adolescence and experience of IPVA in young adult relationships.ConclusionIt is likely that negative labelling and loneliness mediate pathways to IPVA, especially among more disadvantaged young women. The impact of early maltreatment on young people’s wellbeing and own relationships is compounded by disadvantage, disability and ethnicity. Participants’ resilience was enabled by support in the community.

Modeling and Evaluation of Circular Layout Facility in Hospitals

Hospitals encompass an intricate infrastructure with a broad collection of practical units of medical forces. A fine planned facility layout planning is necessary for the smooth performance, in addition, to affording protected and suitable services to patients at the exact point in time. The paper proposed an optimized new facility unidirectional circular pathway of patient movement for achieving better health outcomes. The proposed layout would effectively avoid face-to-face contact of arriving and leaving patients inside a hospital, thus maintaining social distancing to avoid the spread of diseases or infection and hurry up the service deliverance method. A qualitative study was conducted for observing various movements of patients and health service providers inside existing hospital layouts, and semi-structural interviews were conducted to identify various issues of the existing infrastructural layouts inside hospital settings. The performance metrics considered included time, the distance between patients at various interaction points, and the capacity of rooms. The proposed layout was compared with the spring layout and random layout to evaluate the efficiency of the proposed system. This circular design proves to be an extremely suggested design to ensure social distancing in a pandemic or during the spread of infectious diseases.

Investigating Phragmites australis response to copper exposure using physiologic, Fourier Transform Infrared and metabolomic approaches.

Phragmites australis (Cav.) Trin. ex Steud is a landscape plant with resistance to heavy metals that has significance in phytoremediation. However, little is known about the metabolomic background of the heavy metal resistance mechanisms of Phragmites . We studied copper stress on Phragmites and monitored physiological indicators such as malondialdehyde (MDA) and electrolyte leakage (EL). In addition, Fourier Transform Infrared (FTIR) was used to study the related chemical composition in the roots, stems, and leaves under copper stress. Furthermore, LC-MS technology was used to analyse the plants metabolic profile. Results showed that increased copper concentration in Phragmites led to the accumulation of MDA and EL. FTIR spectrum detected the presence of O-H and C=O stretching. O-H stretching was related to the presence of flavonoids, while C=O stretching reflected the presence of protein amide I. The latter was related to the change of amino acid composition. Both flavonoids and amino acids are regarded as contributors to the antioxidant of Phragmites under copper stress. Metabolomics analysis revealed that arginine and ayarin were accumulated and Phragmites leaves responded to copper stress with changes in the pool size of arginine and ayarin. It is speculated that they could improve resistance. Arginine is accumulated through two pathways: the citrulline decomposition and conversion pathway; and the circular pathway composed of ornithine, citrulline, l -argininosuccinate and arginine. Ayarin is synthesised through the quercetin methylation pathway. This study elucidates the antioxidant mechanisms for enhancing its resistance to heavy metal stress, thus improving of phytoremediation efficiency.

Available Pathways for Operationalizing Circular Economy into the Olive Oil Supply Chain: Mapping Evidence from a Scoping Literature Review

Circular economy (CE) is increasingly seen as a promising paradigm for transitioning agri-food systems towards more sustainable models of production and consumption, enabling virtuous and regenerative biological metabolisms based on strategies of eco-efficiency and eco-effectiveness. This contribution seeks to provide a theoretical and empirical framework for operationalizing the CE principles into the olive oil supply chain, that plays a central role in the agroecological systems of the Mediterranean region. A scoping literature review has been conducted in order to identify the available pathways so far explored by scholars for reshaping the olive oil supply chain from a circular perspective. The analyzed literature has been charted on the base of the circular pathway examined, and according to the supply chain subsystem(s) to which it refers. Results are discussed highlighting the main issues, the technology readiness level of the available pathways, the prevailing approaches and knowledge gaps. A synthetic evidence map is provided, framing visually the scrutinized pathways into the Ellen MacArthur Foundation’s CE ‘butterfly’ graph. The work is intended to be a valuable baseline for inquiring how circularity can be advanced in the specific supply chain of olive oil, and which are the strategic opportunities, as well as the barriers to overcome, in order to foster the transition.

An approach to integrate population mobility patterns and sociocultural factors in communicable disease preparedness and response

Complex human movement patterns driven by a range of economic, health, social, and environmental factors influence communicable disease spread. Further, cross-border movement impacts disparate public health systems of neighboring countries, making an effective response to disease importation or exportation more challenging. Despite the array of quantitative techniques and social science approaches available to analyze movement patterns, there continues to be a dearth of methods within the applied public health setting to gather and use information about community-level mobility dynamics. Population Connectivity Across Borders (PopCAB) is a rapidly-deployable toolkit to characterize multisectoral movement patterns through community engagement using focus group discussions or key informant interviews, each with participatory mapping, and apply the results to tailor preparedness and response strategies. The Togo and Benin Ministries of Health (MOH), in collaboration with the Abidjan Lagos Corridor Organization and the US Centers for Disease Control and Prevention, adapted and applied PopCAB to inform cross-border preparedness and response strategies for multinational Lassa fever outbreaks. Initially, the team implemented binational, national-level PopCAB activities in March 2017, highlighting details about a circular migration pathway across northern Togo, Benin, and Nigeria. After applying those results to respond to a cross-border Lassa fever outbreak in February 2018, the team designed an expanded PopCAB initiative in April 2018. In eight days, they trained 54 MOH staff who implemented 21 PopCAB focus group discussions in 14 cities with 224 community-level participants representing six stakeholder groups. Using the newly-identified 167 points of interest and 176 routes associated with a circular migration pathway across Togo, Benin, and Nigeria, the Togo and Benin MOH refined their cross-border information sharing and collaboration processes for Lassa fever and other communicable diseases, selected health facilities with increased community connectivity for enhanced training, and identified techniques to better integrate traditional healers in surveillance and community education strategies. They also integrated the final toolkit in national- and district-level public health preparedness plans. Integrating PopCAB in public health practice to better understand and accommodate population movement patterns can help countries mitigate the international spread of disease in support of improved global health security and International Health Regulations requirements.

Systematics and cryptic diversification of Leptodactylus frogs in the Brazilian campo rupestre

AbstractThe campo rupestre is a unique mountaintop ecosystem in eastern South America, recognised for its endemism and as ecological refugia for plant and animal taxa. Multiple clades of frogs are represented in the Brazilian campo rupestre. One such case is four species of the Leptodactylus fuscus group, three of which are endemic to specific mountain ranges (Leptodactylus camaquara, Leptodactylus oreomantis and Leptodactylus tapiti) and one that is more widespread across different mountain ranges (Leptodactylus cunicularius). In this study, we conducted a phylogenetic analysis of the clade containing the four Leptodactylus species endemic to the campo rupestre ecosystem and explored the biogeographic scenarios of origin and diversification of these montane frogs. The origin and early diversification of this frog clade took place in the Espinhaço Mountain Range (EMR) in the Miocene. This was followed by successive dispersal events to other mountain ranges in a circular pathway and subsequent rapid lineage diversification during the Plio‐Pleistocene transition and early Pleistocene. The diversification of this anuran clade was likely triggered by the Pleistocene climatic oscillations and culminated in the return of one of the montane species to the EMR. Contrasting patterns of phenotypic and genetic divergence indicate cryptic speciation in these frogs unaccompanied by phenotypic disparity. A phenotypically cryptic but highly divergent genetic lineage was found to represent a distinct evolutionary unit in the Northern EMR, described here as a new species (Leptodactylus avivoca sp. n.). The circular dispersal pathway in this frog clade revealed a unique diversification pattern among vertebrates endemic to the Brazilian campo rupestre.

Assessment of 3D printing using fused deposition modeling and selective laser sintering for a circular economy

Plastic today is commonplace. Products and parts made with plastic have short life cycles, ending up in landfills not long after manufacture. Finding new pathways for plastic waste has become a critical focus of sustainability efforts, especially within manufacturing. Thus, research in this field continues to grow in order to determine the feasibility of reclaiming post-consumer plastic for reuse. This paper evaluates the potential for a sustainable, circular pathway for end-of-life plastic material using 3D-printing techniques. To do this, the work investigates two prevalent industrial 3D-printing technologies: selective laser sintering (SLS) and fused deposition modeling (FDM) of polymers. Material-flow and economic models are developed to outline how plastic parts at the end of their life cycle can be processed and reused. Prior works on fundamental material degradation are integrated into mathematical models of cost and operation. This enables mapping of how multiple reuse cycles affect two prevalent industrial polymers: acrylonitrile butadiene styrene (ABS) and polyamide 12 (PA 12). The mapping identifies there is significant opportunity for improving both SLS and FDM 3D-printing technologies when it comes to economic viability and sustainability. Comparison between reuse of FDM using ABS and SLS using PA 12 shows the former costs 82% less than the latter, while also producing 87% less waste than it. While the study established that available industrial 3D-printing technologies can help to reduce plastic waste within manufacturing, a fully circular economy demands materials with less thermal degradation than the primary industrial 3D-printing polymers.

Motion and Trajectory Constraints Control Modeling for Flexible Surgical Robotic Systems.

Success of the da Vinci surgical robot in the last decade has motivated the development of flexible access robots to assist clinical experts during single-port interventions of core intrabody organs. Prototypes of flexible robots have been proposed to enhance surgical tasks, such as suturing, tumor resection, and radiosurgery in human abdominal areas; nonetheless, precise constraint control models are still needed for flexible pathway navigation. In this paper, the design of a flexible snake-like robot is presented, along with the constraints model that was proposed for kinematics and dynamics control, motion trajectory planning, and obstacle avoidance during motion. Simulation of the robot and implementation of the proposed control models were done in Matlab. Several points on different circular paths were used for evaluation, and the results obtained show the model had a mean kinematic error of 0.37 ± 0.36 mm with very fast kinematics and dynamics resolution times. Furthermore, the robot’s movement was geometrically and parametrically continuous for three different trajectory cases on a circular pathway. In addition, procedures for dynamic constraint and obstacle collision detection were also proposed and validated. In the latter, a collision-avoidance scheme was kept optimal by keeping a safe distance between the robot’s links and obstacles in the workspace. Analyses of the results showed the control system was optimal in determining the necessary joint angles to reach a given target point, and motion profiles with a smooth trajectory was guaranteed, while collision with obstacles were detected a priori and avoided in close to real-time. Furthermore, the complexity and computational effort of the algorithmic models were negligibly small. Thus, the model can be used to enhance the real-time control of flexible robotic systems.

Using Music-Based Cadence Entrainment to Manipulate Walking Intensity.

While previous studies indicate an auditory metronome can entrain cadence (in steps per minute), music may also evoke prescribed cadences and metabolic intensities. To determine how modulating the tempo of a single commercial song influences adults' ability to entrain foot strikes while walking and how this entrainment affects metabolic intensity. Twenty healthy adults (10 men and 10 women; mean [SD]: age 23.7 [2.7]y, height 172.8 [9.0]cm, mass 71.5 [16.2]kg) walked overground on a large circular pathway for six 5-min conditions; 3 self-selected speeds (slow, normal, and fast); and 3 trials listening to a song with its tempo modulated to 80, 100, and 125beats per minute. During music trials, participants were instructed to synchronize their step timing with the music tempo. Cadence was measured via direct observation, and metabolic intensity (metabolic equivalents) was assessed using indirect calorimetry. Participants entrained their cadences to the music tempos (mean absolute percentage error = 5.3% [5.8%]). Entraining to a music tempo of 100 beats per minute yielded ≥3 metabolic equivalents in 90% of participants. Trials with music entrainment exhibited greater metabolic intensity compared with self-paced trials (repeated-measures analysis of variance, F1,19 = 8.05, P = .01). This study demonstrates the potential for using music to evoke predictable metabolic intensities.

Using the ReSOLVE framework for circularity in the building and construction industry in emerging markets

Circularity supports the move from linear to circular systems where more efficient, zero waste systems are created by closing material inputs and loops. The design, maintenance, manufacturing and use ensure virgin materials are no longer needed for day to day living. For the built environment sector, building materials and its use underpins the trajectory of circularity in the sector. Improved building materials, increased standardization and appropriate storage and transportation may reduce waste. Increased adaptability and multi-use spaces in buildings support multiple occupants and end users. This paper focuses on understanding the requirements to move to a circular pathway for the building and construction sector in emerging markets, using secondary literature and case studies. The ReSOLVE framework developed by Arup and Ellen MacArthur Foundation consists of Regenerate, Share, Optimize, Loop, Virtualise and Exchange to support circularity in the built environment. Not just the building materials themselves and advanced techniques of construction, but also new business models are required so that the socioeconomic system may also support circularity approaches. Increased digitalisation also supports the adoption of circular opportunities. Emerging economies globally need to consider circular approaches to meet the current and future demands of climate change mitigation and adaptation.

Structure elucidation and proposed de novo synthesis of an unusual mono-rhamnolipid by Pseudomonas guguanensis from Chennai Port area

In this paper, we describe the isolation of an unusual type of high molecular weight monorhamnolipid attached to esters of palmitic, stearic, hexa and octadecanoic acids as against the routinely reported di-rhamnolipids linked to hydroxydecanoic acids. The bioemulsifier was column-purified and the chemical nature of the compound was elucidated using FT-IR, GC-MS and 1D [1H and13C] and 2D NMR. This monorhamnolipid is extracted from a bacterium, Pseudomonas guganensis and is not reported to have biological activities, let alone emulsification abilities. The bacterium continually produced rhamnolipids when nourished with n-hexadecane as its lone carbon source. The extracellularly secreted monorhamnolipids are capable of degrading hydrocarbons, with most preference to n-hexadecane [EI24 of 56 ± 1.42% by 2 mL of the spent medium]. Whilst the crude ethyl acetate partitioned extract had an EI24 of 65 ± 1.43%; the purified rhamnolipid product showed 78 ± 1.75% both at 12.5 mg/mL concentration. The used-up n-hexadecane is biotransformed to prepare its own rhamnolipids which in return is utilized to degrade n-alkanes thus creating a circular pathway which is proposed herein. This bacterium can be seen as a new source of bioemulsifier to reduce hydrocarbon in polluted waters.

Feedback-controlled dynamics of spiral waves in the complex Ginzburg–Landau equation

Spiral dynamics in the complex Ginzburg–Landau equation (CGLE) with a feedback control are studied. It is shown that the spiral tip follows a circular pathway centered at the measuring point after some transients. The attractor radius is a piecewise constant function of the initial distance between the spiral tip and the measuring point, and a piecewise linear increasing function of the time delay in the feedback loop. Many bumps or lobes can be formed from the circular attractor if the time delay becomes relatively long, and the tip path becomes complex. With an increase in the positive feedback gain, the attractor is not changed, but the drift velocity of the spiral tip along such an attractor is linearly increased. When the gain is negative, the tip is attracted to the measuring point from its initial position if the initial distance is relatively small. The variation of the scaling parameter $$\mu $$ in CGLE initiates also transitions between attractors of different size, and the attractor radius is a piecewise function of $$\mu $$ , where it is inversely proportional to a square root of the parameter on each piece. It is also demonstrated that the tip drift velocity has a power-law relation with $$\mu $$ and the wave speed. Some results can be understood by analyzing the drift direction of the spiral tip in the transient process.

Square Street

The logo for a store in Hong Kong called Square Street can be seen in photographs 1 and 2. The main store is located at 15 (XV in Roman numerals) Square Street, and a second store is at 41 (XLIV) Circular Pathway.