Learning from natural sediments to tackle microplastics challenges: A multidisciplinary perspective

Although the study of microplastics in the aquatic environment incorporates a diversity of research fields, it is still in its infancy in many aspects while comparable topics have been studied in other disciplines for decades. In particular, extensive research in sedimentology can provide valuable insights to guide future microplastics research. To advance our understanding of the comparability of natural sediments with microplastics, we take an interdisciplinary look at the existing literature describing particle properties, transport processes, sampling techniques and ecotoxicology. Based on our analysis, we define seven research goals that are essential to improve our understanding of microplastics and can be tackled by learning from natural sediment research, and identify relevant tasks to achieve each goal. These goals address (1) the description of microplastic particles, (2) the interaction of microplastics with environmental substances, (3) the vertical distribution of microplastics, (4) the erosion and deposition behaviour of microplastics, (5) the impact of biota on microplastic transport, (6) the sampling methods and (7) the microplastic toxicity. When describing microplastic particles, we should specifically draw from the knowledge of natural sediments, for example by using shape factors or applying methods for determining the principal dimensions of non-spherical particles. Sediment transport offers many fundamentals that are transferable to microplastic transport, and could be usefully applied. However, major knowledge gaps still exist in understanding the role of transport modes, the influence of biota on microplastic transport, and the importance and implementation of the dynamic behaviour of microplastics as a result of time-dependent changes in particle properties in numerical models. We give an overview of available sampling methods from sedimentology and discuss their suitability for microplastic sampling, which can be used for creating standardised guidelines for future application with microplastics. In order to comprehensively assess the ecotoxicology of microplastics, a distinction must be made between the effects of the polymers themselves, their physical form, the plastic-associated chemicals and the attached pollutants. This review highlights areas where we can rely on understanding and techniques from sediment research - and areas where we need new, microplastic-specific knowledge - and synthesize recommendations to guide future, interdisciplinary microplastic research

Antagonistic Bacterial Interactions Help Shape Host-Symbiont Dynamics within the Fungus-Growing Ant-Microbe Mutualism

Conflict within mutually beneficial associations is predicted to destabilize relationships, and theoretical and empirical work exploring this has provided significant insight into the dynamics of cooperative interactions. Within mutualistic associations, the expression and regulation of conflict is likely more complex than in intraspecific cooperative relationship, because of the potential presence of: i) multiple genotypes of microbial species associated with individual hosts, ii) multiple species of symbiotic lineages forming cooperative partner pairings, and iii) additional symbiont lineages. Here we explore complexity of conflict expression within the ancient and coevolved mutualistic association between attine ants, their fungal cultivar, and actinomycetous bacteria (Pseudonocardia). Specifically, we examine conflict between the ants and their Pseudonocardia symbionts maintained to derive antibiotics against parasitic microfungi (Escovopsis) infecting the ants' fungus garden. Symbiont assays pairing isolates of Pseudonocardia spp. associated with fungus-growing ants spanning the phylogenetic diversity of the mutualism revealed that antagonism between strains is common. In contrast, antagonism was substantially less common between more closely related bacteria associated with Acromyrmex leaf-cutting ants. In both experiments, the observed variation in antagonism across pairings was primarily due to the inhibitory capabilities and susceptibility of individual strains, but also the phylogenetic relationships between the ant host of the symbionts, as well as the pair-wise genetic distances between strains. The presence of antagonism throughout the phylogenetic diversity of Pseudonocardia symbionts indicates that these reactions likely have shaped the symbiosis from its origin. Antagonism is expected to prevent novel strains from invading colonies, enforcing single-strain rearing within individual ant colonies. While this may align ant-actinomycete interests in the bipartite association, the presence of single strains of Pseudonocardia within colonies may not be in the best interest of the ants, because increasing the diversity of bacteria, and thereby antibiotic diversity, would help the ant-fungus mutualism deal with the specialized parasites

The Gracilis Myocutaneous Free Flap: A Quantitative Analysis of the Fasciocutaneous Blood Supply and Implications for Autologous Breast Reconstruction

BACKGROUND: Mastectomies are one of the most common surgical procedures in women of the developed world. The gracilis myocutaneous flap is favoured by many reconstructive surgeons due to the donor site profile and speed of dissection. The distal component of the longitudinal skin paddle of the gracilis myocutaneous flap is unreliable. This study quantifies the fasciocutaneous vascular territories of the gracilis flap and offers the potential to reconstruct breasts of all sizes. METHODS: Twenty-seven human cadaver dissections were performed and injected using lead oxide into the gracilis vascular pedicles, followed by radiographic studies to identify the muscular and fasciocutaneous perforator patterns. The vascular territories and choke zones were characterized quantitatively using the 'Lymphatic Vessel Analysis Protocol' (LVAP) plug-in for Image J® software. RESULTS: We found a step-wise decrease in the average vessel density from the upper to middle and lower thirds of both the gracilis muscle and the overlying skin paddle with a significantly higher average vessel density in the skin compared to the muscle. The average vessel width was greater in the muscle. Distal to the main pedicle, there were either one (7/27 cases), two (14/27 cases) or three (6/27 cases) minor pedicles. The gracilis angiosome was T-shaped and the maximum cutaneous vascular territory for the main and first minor pedicle was 35 × 19 cm and 34 × 10 cm, respectively. CONCLUSION: Our findings support the concept that small volume breast reconstructions can be performed on suitable patients, based on septocutaneous perforators from the minor pedicle without the need to harvest any muscle, further reducing donor site morbidity. For large reconstructions, if a 'T' or tri-lobed flap with an extended vertical component is needed, it is important to establish if three territories are present. Flap reliability and size may be optimized following computed tomographic angiography and surgical delay

In situ TEM synthesis of Y-junction carbon nanotube by electromigration induced soldering

In this work, we utilize Joule heating to convert Pt-embedded amorphous carbon nanofiber (CNF) to multiwall carbon nanotube (CNT) in a transmission electron microscope (TEM). The transformation process of Pt-embedded amorphous CNF to multiwall CNT and nano-soldering process using Pt encapsulated CNT was investigated in TEM in detail. Molten Pt-encapsulated inside CNF and CNT always flowed towards the anode, proving electromigration to be the dominant force over thermal migration. Controllable electromigration of Pt was utilized to connect the Pt-included CNT to another CNT, thus forming a seamlessly welded CNT structure. Further, two separate CNF were brought together to form Y-contact which was transformed into Y-junction CNT structure by controlled electromigration of Pt. Changes in morphology and electrical property during CNT formation and nano-soldering were probed in real time with high resolution TEM. Our method provides a procedure for the position control synthesis of CNT and its nano-soldering which can be an important step for future development of a CNT based nanoelectrical circuit

L-Band Quantum-dash Self-Injection Locked Multiwavelength Laser Source for Future WDM Access Networks

We propose and demonstrate a compact, cost-effective, multiwavelength laser source employing self-injection locking scheme on InAs/InP quantum-dash (Qdash) laser diode. The device is shown to exhibit Fabry-Perot modes or subcarriers selectivity of 1 to 16 between ∼1600-1610 nm, with corresponding mode power (side mode suppression ratio) variation of ∼10 (∼38) to ∼-2.5 (∼22) dBm (dB), and able to extend beyond 1610 nm, thereby encompassing >30 optical carriers. Then, we utilized a single self-locked optical carrier at 1609.6 nm to successfully transmit 128 Gb/s dual-polarization quadrature phase shift keying signal over 20 km single mode fiber with ∼-16 dBm receiver sensitivity. To stem the viability of unifying the transceivers and addressing the requirements of next generation access networks, we propose self-seeded Qdash laser based wavelength division multiplexed passive optical network, capable of reaching a data capacity of 2.0 Tb/s (16 × 128, Gbs) in L-band

Developing Multimedia Enhanced Content to Raise HIV/AIDS Awareness to Children

Part 4: Sustainable ICT, Informatics, Education and Learning in a Turbulent World - “Doing the Safari Way”International audienceIt is estimated that more than two-thirds (70%) of all the 35 million people living with Human Immunodeficiency Virus (HIV) in the world are in Sub-Saharan Africa. Tanzania as one of the country in sub-Sahara region is no exceptional, more than 60% of all new HIV infections in Tanzania occur among young people. While almost all children in Tanzania aged 15 years and below have heard about HIV/AIDS, less than half have enough knowledge to protect themselves against infections. It is known that HIV/AIDS is taught in primary schools, although majority of the pupils demonstrated a very low level of knowledge about HIV/AIDS. This raised a concern on the effectiveness of HIV/AIDS and life skills education in primary schools. Information and Communication Technology (ICT) has a great potential for HIV/AIDS education to children because they like and enjoy to use ICT resources for entertainment, learning, networking and communication. Hence, it is important to apply technology for educational in teaching HIV/AIDS through the use of multimedia contents in accordance to the local context of Tanzanian curriculum for primary schools. Therefore, the main objective of this paper is to develop multimedia enhanced contents to raise HIV/AIDS awareness to children. ADDIE model, Adobe Flash Professional 5, Action Script programming language and articulate storyline2 authoring tool, were used in the development of multimedia enhanced contents. Results show that level of HIV/AIDS knowledge among pupils after using the interactive multimedia has been enhanced in the tested three knowledge areas (causes, prevention and effects). Results in this paper suggest that, multimedia enhanced contents can be used to complement text book based learning approach in enhancing HIV/AIDS awareness for children in primary schools in Tanzania