86 research outputs found

    The Impact of Retailer-Supplier Cooperation and Decision-Making Uncertainty on Supply Chain Performance

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    Buyer-supplier relationships have been increasingly considered a critical part of contemporary supply chain management. In response to dynamic and unpredictable market changes, buyers and suppliers enter into cooperative relationships to pursue individual goals and joint goals for better economic and non-economic performance of the supply chain. On the other hand, cooperation between channel members is surrounded by uncertainty, which can create a detrimental impact on the performance of a supply chain. Previous research has focused on various aspects of uncertainty that could affect supply chain member behaviour. The present research contends that relationship behavioural factors play an important role in increasing or mitigating channel members’ perceived uncertainty in their supply or purchase decision-making. Specifically, the purpose of this research is to investigate the impact of retailer-supplier cooperation and retailer/supplier’s decision-making uncertainty (DMU) on retail supply chain performance from the perspectives of both the retailer and the supplier. A holistic model was developed as the theoretical framework for this conceptualisation. A sample of 202 retailers and 64 suppliers in the sporting goods retail business in Taiwan was used to separately test a number of hypothesised relationships by using structural equation modelling (SEM). The findings indicate that both cooperation and DMU are the key determinants of retail supply chain performance, including financial performance and non-financial performance (i.e., supply flexibility and customer service). Financial performance is positively affected by retailer-supplier cooperation and negatively affected by DMU in both the retailer model and the supplier model. The five dimensions of retailer-supplier cooperation (i.e. trust, guanxi, dependence, coercive power and non-coercive power) have significant effects on cooperation. However, apart from guanxi with the retailer/supplier, neither other relationship dimensions nor retailer-supplier cooperation have any influence on retailer’s DMU or supplier’s DMU. The results also indicate that differences and similarities exist across retailers and suppliers with respect to the effects of several relationship dimensions on cooperation and uncertainty. 2 The holistic empirical model developed for this research contributes further to understanding the links, which have been lacking in the extant channel relationship literature and supply chain management literature, between buyer-supplier relationships, DMU, and supply chain performance. The findings that a retailer/supplier’s DMU can erode the performance of a supply chain in various aspects highlight the need for improvement in some areas of supply chain efficiency and effectiveness, through cooperation-enhancing actions between the retailer and the supplier. From a managerial perspective, the performance improvement in the supply chain, in turn, will motivate more reciprocal commitment and efforts from the retailer and the supplier to maintain their working relationship. As such, mutual trust and enriched guanxi, dependence and non-coercive power help both the retailer and the supplier to have less uncertainty in their purchase/supply decision-making process. It creates a win-win position for both parties in the supply chain

    An Expanded Set of Amino Acid Analogs for the Ribosomal Translation of Unnatural Peptides

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    BACKGROUND: The application of in vitro translation to the synthesis of unnatural peptides may allow the production of extremely large libraries of highly modified peptides, which are a potential source of lead compounds in the search for new pharmaceutical agents. The specificity of the translation apparatus, however, limits the diversity of unnatural amino acids that can be incorporated into peptides by ribosomal translation. We have previously shown that over 90 unnatural amino acids can be enzymatically loaded onto tRNA. METHODOLOGY/PRINCIPAL FINDINGS: We have now used a competition assay to assess the efficiency of tRNA-aminoacylation of these analogs. We have also used a series of peptide translation assays to measure the efficiency with which these analogs are incorporated into peptides. The translation apparatus tolerates most side chain derivatives, a few alpha,alpha disubstituted, N-methyl and alpha-hydroxy derivatives, but no beta-amino acids. We show that over 50 unnatural amino acids can be incorporated into peptides by ribosomal translation. Using a set of analogs that are efficiently charged and translated we were able to prepare individual peptides containing up to 13 different unnatural amino acids. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that a diverse array of unnatural building blocks can be translationally incorporated into peptides. These building blocks provide new opportunities for in vitro selections with highly modified drug-like peptides

    Peptide conjugates for biological applications

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    Chemical tools and materials for Biological/Medicinal applications

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    Guest editors Xuehai Yan and Jan C. M. van Hest discuss in their editorial to this special issue recent advances in chemical tools and materials that have significantly promoted both preventive and therapeutic biomedicine, and highlight the the state‐of‐the‐art contributions in this research field featured in this special issue

    Artificial cells: synthetic compartments with life-like functionality and adaptivity

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    Cells are highly advanced microreactors that form the basis of all life. Their fascinating complexity has inspired scientists to create analogs from synthetic and natural components using a bottom-up approach. The ultimate goal here is to assemble a fully man-made cell that displays functionality and adaptivity as advanced as that found in nature, which will not only provide insight into the fundamental processes in natural cells but also pave the way for new applications of such artificial cells.\u3cbr/\u3e\u3cbr/\u3eIn this Account, we highlight our recent work and that of others on the construction of artificial cells. First, we will introduce the key features that characterize a living system; next, we will discuss how these have been imitated in artificial cells. First, compartmentalization is crucial to separate the inner chemical milieu from the external environment. Current state-of-the-art artificial cells comprise subcompartments to mimic the hierarchical architecture of eukaryotic cells and tissue. Furthermore, synthetic gene circuits have been used to encode genetic information that creates complex behavior like pulses or feedback. Additionally, artificial cells have to reproduce to maintain a population. Controlled growth and fission of synthetic compartments have been demonstrated, but the extensive regulation of cell division in nature is still unmatched.\u3cbr/\u3e\u3cbr/\u3eHere, we also point out important challenges the field needs to overcome to realize its full potential. As artificial cells integrate increasing orders of functionality, maintaining a supporting metabolism that can regenerate key metabolites becomes crucial. Furthermore, life does not operate in isolation. Natural cells constantly sense their environment, exchange (chemical) signals, and can move toward a chemoattractant. Here, we specifically explore recent efforts to reproduce such adaptivity in artificial cells. For instance, synthetic compartments have been produced that can recruit proteins to the membrane upon an external stimulus or modulate their membrane composition and permeability to control their interaction with the environment. A next step would be the communication of artificial cells with either bacteria or another artificial cell. Indeed, examples of such primitive chemical signaling are presented. Finally, motility is important for many organisms and has, therefore, also been pursued in synthetic systems. Synthetic compartments that were designed to move in a directed, controlled manner have been assembled, and directed movement toward a chemical attractant is among one of the most life-like directions currently under research.\u3cbr/\u3e\u3cbr/\u3eAlthough the bottom-up construction of an artificial cell that can be truly considered “alive” is still an ambitious goal, the recent work discussed in this Account shows that this is an active field with contributions from diverse disciplines like materials chemistry and biochemistry. Notably, research during the past decade has already provided valuable insights into complex synthetic systems with life-like properties. In the future, artificial cells are thought to contribute to an increased understanding of processes in natural cells and provide opportunities to create smart, autonomous, cell-like materials.\u3cbr/\u3

    Compartmentalization approaches in soft matter science: from nanoreactor development to organelle mimics

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    Compartmentalization is an essential feature found in living cells to ensure that biological processes occur without being affected by undesired external influences. Over the years many scientists have designed self-assembled soft matter structures that mimic these natural catalytic compartments. The rationale behind this research is threefold. First of all, compartmentalization leads to the creation of a secluded environment for the catalytic species, which solves compatibility issues and which can improve catalyst efficiency and selectivity. Secondly, nano- and micro-compartments are constructed with the aim to obtain microenvironments that more closely mimic the cellular architecture. These biomimetic platforms are used to attain a better understanding of how cellular processes are executed. Thirdly, natural design rules are applied to create biomolecular assemblies with unusual functionality, which for example are used as artificial organelles. Here, recent developments will be discussed regarding these compartmentalized catalytic systems, with a selected number of illustrative examples to demonstrate which strategies have been followed, and to show to what extent the ambitious goals of this field of science have been reached. The focus here is on the field of soft matter science, covering the wide spectrum from polymeric assemblies to protein nanocages

    Synthetic pathways to tetrahydrocannabinol (THC): an overview

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    The therapeutic effects of molecules produced by the plant speciesCannabis sativahave since their discovery captured the interest of scientists and society, and have spurred the development of a multidisciplinary scientific field with contributions from biologists, medical specialists and chemists. Decades after the first isolation of some of the most bioactive tetrahydrocannabinols, current research is mostly dedicated to exploiting the chemical versatility of this relevant compound class with regard to its therapeutic potential. This review will primarily focus on synthetic pathways utilised for the synthesis of tetrahydrocannabinols and derivatives thereof, including chiral pool-based and asymmetric chemo- and biocatalytic approaches

    The hallmarks of living systems:Towards creating artificial cells

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    \u3cp\u3eDespite the astonishing diversity and complexity of living systems, they all share five common hallmarks: compartmentalization, growth and division, information processing, energy transduction and adaptability. In this review, we give not only examples of how cells satisfy these requirements for life and the ways in which it is possible to emulate these characteristics in engineered platforms, but also the gaps that remain to be bridged. The bottom-up synthesis of life-like systems continues to be driven forward by the advent of new technologies, by the discovery of biological phenomena through their transplantation to experimentally simpler constructs and by providing insights into one of the oldest questions posed by mankind, the origin of life on Earth.\u3c/p\u3

    Feedback-induced temporal control of “breathing” polymersomes to create self-adaptive nanoreactors

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    \u3cbr/\u3e\u3cbr/\u3eHere we present the development of self-regulated “breathing” polymersome nanoreactors that show temporally programmable biocatalysis induced by a chemical fuel. pH-sensitive polymersomes loaded with horseradish peroxidase (HRP) and urease were developed. Addition of an acidic urea solution (“fuel”) endowed the polymersomes with a transient size increase and permeability enhancement, driving a temporal “ON” state of the HRP enzymatic catalysis; subsequent depletion of fuel led to shrinking of the polymersomes, resulting in the catalytic “OFF” state. Moreover, the nonequilibrium nanoreactors could be reinitiated several cycles as long as fuel was supplied. This feedback-induced temporal control of catalytic activity in polymersome nanoreactors provides a platform for functional nonequilibrium systems as well as for artificial organelles with precisely controlled adaptivity.\u3cbr/\u3

    Self-regulated and temporal control of a breathing microgel mediated by enzymatic reaction

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    Naturally occurring systems have the ability to self-regulate, which plays a key role in their structural and functional adaptation. The autonomous behavior in living systems is biocatalytically controlled by the continuous consumption of energy to remain in a non-equilibrium condition. In this work, we show the construction of a self-regulated breathing microgel that uses chemical fuels to keep the system in the out-of-equilibrium state. The enzyme urease is utilized to program a feedback-induced pH change, which in turn tunes the size switch and fluorescence intensity of the microgel. A continuous supply of chemical fuels to the system allows the process to be reversible. This microgel with tunable autonomous properties provides insights into the design of artificial systems and dynamic soft materials
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