Degradable polyethylene nanocomposites with silica, silicate and thermally reduced graphene using oxo-degradable pro-oxidant

Polyethylene nanocomposites with silica, alumino-silicate and thermally reduced graphene were generated by adding pro-oxidant additive. Additive resulted in early degradation of pure polymer, however, the degradation was delayed in the presence of fillers. Graphene resulted in maximum extent of enhancement of peak degradation temperature (13–14 °C depending on the additive content) followed by silicate and silica. Additive also resulted in enhancement of polymer crystallinity, which was further aided by the filler, though no change in peak melting and crystallization temperatures was observed. The graphene and silicate particles were also observed to be uniformly dispersed in polymer matrix, whereas some aggregates were present in silica based composites. In graphene composite with 2.5 wt% additive content, the tensile modulus was increased by 1.95 times that of pure polymer. Increasing the additive content was also observed to enhance the mechanical performance. For instance, graphene nanocomposite with 1 % additive content had 40 % and 33 % increment in storage modulus at 50 °C and 70 °C respectively as compared to pure PE. The thick plaques of composites exhibited oxo-degradation in the presence of pro-oxidant with silica and silicate composites with 2.5 wt% additive having 100 % degree of embrittlement in 15–16 months at 30 °C. Graphene composites also exhibited ∼50 % embrittlement for the same conditions. The filler particles were observed to delay the time needed to attain embrittlement due to reduction in oxygen permeation in the matrix as well as UV absorption, however, these materials confirmed that degradation of the materials could be successfully tuned without sacrificing the mechanical, thermal and rheological properties of the nanocomposites.

Enhancement of Thiamin Content in Arabidopsis thaliana by Metabolic Engineering

Thiamin is an essential nutrient in the human diet. Severe thiamin deficiency leads to beriberi, a lethal disease which is common in developing countries. Thiamin biofortification of staple food crops is a possible strategy to alleviate thiamin deficiency-related diseases. In plants, thiamin plays a role in the response to abiotic and biotic stresses, and data from the literature suggest that boosting thiamin content could increase resistance to stresses. Here, we tested an engineering strategy to increase thiamin content in Arabidopsis. Thiamin is composed of a thiazole ring linked to a pyrimidine ring by a methylene bridge. THI1 and THIC are the first committed steps in the synthesis of the thiazole and pyrimidine moieties, respectively. Arabidopsis plants were transformed with a vector containing the THI1-coding sequence under the control of a constitutive promoter. Total thiamin leaf content in THI1 plants was up approximately 2-fold compared with the wild type. THI1-overexpressing lines were then crossed with pre-existing THIC-overexpressing lines. Resulting THI1 × THIC plants accumulated up to 3.4- and 2.6-fold more total thiamin than wild-type plants in leaf and seeds, respectively. After inoculation with Pseudomonas syringae, THI1 × THIC plants had lower populations than the wild-type control. However, THI1 × THIC plants subjected to various abiotic stresses did not show any visible or biochemical changes compared with the wild type. We discuss the impact of engineering thiamin biosynthesis on the nutritional value of plants and their resistance to biotic and abiotic stresses.

Regenerative Engineering of Cartilage Using Adipose-Derived Stem Cells

Injury to the articular cartilage occurs commonly in the general population and undergoes minimal spontaneous healing. Traditional methods of cartilage repair provide no long-term cure and are significant causes of morbidity. For this reason, stem cell therapies have recently been investigated for their ability to regenerate cartilage, and the results have been promising. Since the discovery that adipose tissue is a major source of mesenchymal stem cells in 2001, scientists have been studying the use of adipose-derived stem cells (ASCs) for the treatment of various disorders including lesions of the articular cartilage. ASCs hold several advantages over autologous chondrocytes for cartilage repair, including but not limited to their anti-inflammatory effects, their multi-lineage differentiation potential, and their ability to form new cartilage in a defect. Whereas several investigations have been made in in vitro and animal models, there have been surprisingly little clinical studies on the intra-articular use of adipose-derived stem cells, despite their first isolation about a decade and a half ago. The few studies that have been conducted are encouraging. With approval for various stem cell therapies on the horizon, this review seeks to update the clinician and the researcher on the current state-of-the-art use of adipose-derived stem cells for the treatment of cartilage disorders and the regenerative engineering of cartilaginous tissue.

A better way of fitting clips? A comparative study with respect to physical workload

The clip fitting task is a frequently encountered assembly operation in the car industry. It can cause upper limb pain. During task laboratory simulations, upper limb muscular activity and external force were compared for 4 clip fitting methods: with the bare hand, with an unpowered tool commonly used at a company and with unpowered and powered prototype tools. None of the 4 fitting methods studied induced a lower overall workload than the other three. Muscle activity was lower at the dominant limb when using the unpowered tools and at the non-dominant limb with the bare hand or with the powered tool. Fitting clips with the bare hand required a higher external force than fitting with the three tools. Evaluation of physical workload was different depending on whether external force or muscle activity results were considered. Measuring external force only, as recommended in several standards, is insufficient for evaluating physical workload.

The role of albumin receptors in regulation of albumin homeostasis: Implications for drug delivery

Albumin is the most abundant protein in blood and acts as a molecular taxi for a plethora of small insoluble substances such as nutrients, hormones, metals and toxins. In addition, it binds a range of medical drugs. It has an unusually long serum half-life of almost 3weeks, and although the structure and function of albumin has been studied for decades, a biological explanation for the long half-life has been lacking. Now, recent research has unravelled that albumin-binding cellular receptors play key roles in the homeostatic regulation of albumin. Here, we review our current understanding of albumin homeostasis with a particular focus on the impact of the cellular receptors, namely the neonatal Fc receptor (FcRn) and the cubilin-megalin complex, and we discuss their importance on uses of albumin in drug delivery.

Engineering and Biology: Counsel for a Continued Relationship

Biologists frequently draw on ideas and terminology from engineering. Evolutionary systems biology-with its circuits, switches, and signal processing-is no exception. In parallel with the frequent links drawn between biology and engineering, there is ongoing criticism against this cross-fertilization, using the argument that over-simplistic metaphors from engineering are likely to mislead us as engineering is fundamentally different from biology. In this article, we clarify and reconfigure the link between biology and engineering, presenting it in a more favorable light. We do so by, first, arguing that critics operate with a narrow and incorrect notion of how engineering actually works, and of what the reliance on ideas from engineering entails. Second, we diagnose and diffuse one significant source of concern about appeals to engineering, namely that they are inherently and problematically metaphorical. We suggest that there is plenty of fertile ground left for a continued, healthy relationship between engineering and biology.

The machine conception of the organism in development and evolution: a critical analysis

This article critically examines one of the most prevalent metaphors in contemporary biology, namely the machine conception of the organism (MCO). Although the fundamental differences between organisms and machines make the MCO an inadequate metaphor for conceptualizing living systems, many biologists and philosophers continue to draw upon the MCO or tacitly accept it as the standard model of the organism. The analysis presented here focuses on the specific difficulties that arise when the MCO is invoked in the contexts of development and evolution. In developmental biology the MCO underlies a logically incoherent model of ontogeny, the genetic program, which serves to legitimate three problematic theses about development: genetic animism, neo-preformationism, and developmental computability. In evolutionary biology the MCO is responsible for grounding unwarranted theoretical appeals to the concept of design as well as to the interpretation of natural selection as an engineer, which promote a distorted understanding of the process and products of evolutionary change. Overall, it is argued that, despite its heuristic value, the MCO today is impeding rather than enabling further progress in our comprehension of living systems.

Interdisciplinary doctorial supervision: lessons for nurse education and practice

BACKGROUND

This paper concerns a reflection on one interdisciplinary doctorate supervision project. It outlines key elements for success within this supervisory context.

AIM

The aim of this paper is to present a reflection on interdisciplinary doctorate supervision project experience and examine these experiences in light of literature on the topic.

METHODS

Reflection was carried out using Rolfe et al. (2010) framework for reflexivity.

FINDINGS

The supervised engineering project aimed to develop, demonstrate and evaluate a new framework for the design of customisable assistive technology (AT) which involved professionals working with AT and users with disabilities. As this research occurs in between disciplines, it required an innovative and interdisciplinary approach, with an ultimate merger between health sciences and design engineering disciplines and external liaison with adults with disabilities and a disability service provider.

CONCLUSION

Interdisciplinary research is popular contemporarily and addresses societal needs. In the case outlined, clear understandings were developed, in addition to clear territorial boundaries that helped guide the novel research. Steps to success in interdisciplinary research supervision include selecting the appropriate interdisciplinary team; ensuring open communication; establishing and agreeing boundaries of the research and supervision; keeping an open mind; tolerance of lack of expertise in some areas; regular meetings and communication; keeping the student focused and agreeing publication plans in advance.

coli

Uroporphyrinogen III methyltransferase (UMT) is a novel reporter owing to the catalytic products in the cells that emit strong red fluorescence under UV light. Here, we engineered the gene encoding the functional barley UMT (bUMT) by error-prone PCR and broadened the application UMT as a red fluorescent reporter in Escherichia coli. A variant, termed mbUMT, was selected and emitted stronger cell fluorescence than the wild type bUMT expressed in different E. coli strains, under different promoters and induction conditions respectively. The constructed mbUMT with a C-terminal ssrA tag was degraded in cells by the protease ClpXP encoded by E. coli chromosome, whereas the bUMT was expressed as active aggregates. Before they are exported to the periplasm, both proteins catalyze the substrate in the cytoplasm and emit cell fluorescence. The results suggested that the evolved bUMT is a better candidate to monitor in vivo degradation by E. coli ClpXP.

Designing and evaluating a STEM teacher learning opportunity in the research university

This study examines the design and evaluation strategies for a year-long teacher learning and development experience, including their effectiveness, efficiency and recommendations for strategic redesign. Design characteristics include programmatic features and outcomes: cognitive, affective and motivational processes; interpersonal and social development; and performance activities. Program participants were secondary math and science teachers, partnered with engineering faculty mentors, in a research university-based education and support program. Data from multiple sources demonstrated strengths and weaknesses in design of the program's learning environment, including: face-to-face and via digital tools; on-site and distance community interactions; and strategic evaluation tools and systems. Implications are considered for the strategic design and evaluation of similar grant-funded research experiences intended to support teacher learning, development and transfer.

Protein disulfide engineering

Improving the stability of proteins is an important goal in many biomedical and industrial applications. A logical approach is to emulate stabilizing molecular interactions found in nature. Disulfide bonds are covalent interactions that provide substantial stability to many proteins and conform to well-defined geometric conformations, thus making them appealing candidates in protein engineering efforts. Disulfide engineering is the directed design of novel disulfide bonds into target proteins. This important biotechnological tool has achieved considerable success in a wide range of applications, yet the rules that govern the stabilizing effects of disulfide bonds are not fully characterized. Contrary to expectations, many designed disulfide bonds have resulted in decreased stability of the modified protein. We review progress in disulfide engineering, with an emphasis on the issue of stability and computational methods that facilitate engineering efforts.

Engineering soluble tobacco etch virus protease accompanies the loss of stability

Tobacco etch virus protease (TEVp) is a widely used tool enzyme in biological studies. To improve the solubility of recombinant TEVp, three variants, including the double mutant (L56V/S135G), the triple mutant (T17S/N68D/I77V), and the quintuple mutant (T17S/L56V/N68D/I77V/S135G), have been developed, however, with little information on functional stability. Here we investigated the solubility and stability of the three TEVp mutants under different temperature and denaturants, and in Escherichiacoli with different cultural conditions. The quintuple mutant showed the highest solubility and thermostablity, and the double mutant was most resistant to the denaturants. The double mutant folded best in E. coli cells at 37°C with or without the co-expressed molecular chaperones GroEL, GroES and GrpE. The least soluble wild type TEVp displayed better tolerance to denaturants than the triple and the quintuple mutants. All results demonstrated that TEVp is not engineered to embody the most desirable solubility and stability by the current mutations.

Characterization of two geraniol synthases from Valeriana officinalis and Lippia dulcis: similar activity but difference in subcellular localization

Two geraniol synthases (GES), from Valeriana officinalis (VoGES) and Lippia dulcis (LdGES), were isolated and were shown to have geraniol biosynthetic activity with Km values of 32 µM and 51 µM for GPP, respectively, upon expression in Escherichia coli. The in planta enzymatic activity and sub-cellular localization of VoGES and LdGES were characterized in stable transformed tobacco and using transient expression in Nicotiana benthamiana. Transgenic tobacco expressing VoGES or LdGES accumulate geraniol, oxidized geraniol compounds like geranial, geranic acid and hexose conjugates of these compounds to similar levels. Geraniol emission of leaves was lower than that of flowers, which could be related to higher levels of competing geraniol-conjugating activities in leaves. GFP-fusions of the two GES proteins show that VoGES resides (as expected) predominantly in the plastids, while LdGES import into to the plastid is clearly impaired compared to that of VoGES, resulting in both cytosolic and plastidic localization. Geraniol production by VoGES and LdGES in N. benthamiana was nonetheless very similar. Expression of a truncated version of VoGES or LdGES (cytosolic targeting) resulted in the accumulation of 30% less geraniol glycosides than with the plastid targeted VoGES and LdGES, suggesting that the substrate geranyl diphosphate is readily available, both in the plastids as well as in the cytosol. The potential role of GES in the engineering of the TIA pathway in heterologous hosts is discussed.

Engineering Clostridia Neurotoxins with elevated catalytic activity

BoNT/B and TeNT cleave substrate VAMP2 at the same scissile bond, yet these two toxins showed different efficiency on substrate hydrolysis and had different requirements for the recognition of P2' site of VAMP2, E(78). These differences may be due to their different composition of their substrate recognition pockets in the active site. Swapping of LC/T S1' pocket residue, L(230), with the corresponding isoleucine in LC/B increased LC/T activity by ∼25 fold, while swapping of LC/B S1' pocket residue, S(201), with the corresponding proline in LC/T increased LC/B activity by ∼10 fold. Optimization of both S1 and S1' pocket residues of LC/T, LC/T (K(168)E, L(230)I) elevated LC/T activity by more than 100-fold. The highly active LC/T derivative engineered in this study has the potential to be used as a more effective tool to study mechanisms of exocytosis in central neuron. The LC/B derivative with elevated activity has the potential to be developed into novel therapy to minimize the impact of immunoresistance during BoNT/B therapy.

Introduction to cognition in science and technology

Cognitive studies of science and technology have had a long history of largely independent research projects that have appeared in multiple outlets, but rarely together. The emergence of a new International Society for Psychology of Science and Technology suggests that this is a good time to put some of the latest work in this area into topiCS in a way that will both acquaint readers with the cutting edge in this domain and also give them a hint of its history. One core theme includes how scientists, inventors, and engineers represent and solve problems; another, related theme is the extent to which they distribute and share cognition. Methodologies include fine-grained studies of historical records, protocols of working scientists, observations and comparisons of engineering science laboratories, and computational simulations designed both to serve as research tools and also to improve scientific problem-solving. The series of articles will conclude with the Associate Editor's suggestions for future research.