Substrate induction and glucose repression of maltose utilization by Streptomyces coelicolor A3(2) is controlled by malR, a member of the lacI-galR family of regulatory genes

malR of Strepomyces coelicolor A3(2) encodes a homologue of the Lacl/Galr family of repressor proteins, and is divergently transcribed from the malEFG gene cluster, which encodes components of an ATP-dependent transport system that is required for maltose utilization. Transcription of malE was induced by maltose and repressed by glucose. Disruption or deletion of malR resulted in constitutive, glucose-insensitive malE transcription at a level markedly above that observed in the parental malR+ strain, and overproduction of MalR prevented growth on maltose as carbon source. Consequently, MalR plays a crucial role in both substrate induction and glucose repression of maltose utilization. MalR is expressed from a single promoter with transcription initiating at the first G of the predicted GTG translataion start codon

Watasemycin biosynthesis in Streptomyces venezuelae : thiazoline C-methylation by a type B radical-SAM methylase homologue

2-Hydroxyphenylthiazolines are a family of iron-chelating nonribosomal peptide natural products that function as virulence-conferring siderophores in various Gram-negative bacteria. They have also been reported as metabolites of Gram-positive Streptomyces species. Transcriptional analyses of Streptomyces venezuelae ATCC 10712 revealed that its genome contains a putative 2-hydroxyphenylthiazoline biosynthetic gene cluster. Heterologous expression of the gene cluster in Streptomyces coelicolor M1152 showed that the mono- and dimethylated derivatives, thiazostatin and watasemycin, respectively, of the 2-hydroxyphenylthiazoline enantiopyochelin are two of its metabolic products. In addition, isopyochelin, a novel isomer of pyochelin containing a C-methylated thiazolidine, was identified as a third metabolic product of the cluster. Metabolites with molecular formulae corresponding to aerugine and pulicatins A/B were also detected. The structure and stereochemistry of isopyochelin were confirmed by comparison with synthetic standards. The role of two genes in the cluster encoding homologues of PchK, which is proposed to catalyse thiazoline reduction in the biosynthesis of enantiopyochelin in Pseudomonas protegens, was investigated. One was required for the production of all the metabolic products of the cluster, whereas the other appears not to be involved in the biosynthesis of any of them. Deletion of a gene in the cluster encoding a type B radical-SAM methylase homologue abolished the production of watasemycin, but not thiazostatin or isopyochelin. Feeding of thiazostatin to the mutant lacking the functional PchK homologue resulted in complete conversion to watasemycin, demonstrating that thiazoline C-methylation by the type B radical-SAM methylase homologue is the final step in watasemycin biosynthesis

DESIGNING END USE COMPONENTS FOR ADDITIVE MANUFACTURING Exploring experiences, knowledge and information requirements

The primary aim of this study was to develop an understanding of the experience, the current knowledge regarding the design of end-user components for series production in additive manufacturing (AM) and the information needs of designers involved in designing end-user components for AM. To achieve this, the survey intended to uncover the following aspects of the topic: 1. If and how frequently AM technologies are used by designers for series production of end-user components 2. To what extend designers have had experience of designing end-user components for AM 3. Which aspects are important when designing end-user components for additive 4. Why designers have or not have designed end-user components for series production in AM 5. How designers have learned how to design for AM and which resources they have used 6. What designers would like to know about Design for AM 7. How they prefer this information to be conveye

Integrated Flush Air Data Sensing System Modeling for Planetary Entry Guidance with Direct Force Control

Flush air data sensing (FADS) systems have been previously used at both Earth and Mars to provide onboard estimates of angle of attack, sideslip angle, and dynamic pressure. However, these FADS data were often not used in an in-the-loop sense to inform the onboard guidance and control systems. A method to integrate FADS-derived density and wind estimates with a numerical predictor-corrector guidance algorithm is presented. The method is demonstrated in a high-fidelity simulation of a human-scale Mars entry vehicle that utilizes a hypersonic inflatable aerodynamic decelerator (HIAD) with direct force control. Effects on guidance commands and state uncertainties both with and without FADS system modeling are presented and discussed

A framework for mapping design for additive manufacturing knowledge for industrial and product design

© 2018, © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Design for Additive Manufacturing (DfAM) is a growing field of enquiry. Over the past few years, the scientific community has begun to explore this topic to provide a basis for supporting professional design practice. However, current knowledge is still largely fragmented, difficult to access and inconsistent in language and presentation. This paper seeks to collate and organise this dispersed but growing body of knowledge, using a single and coherent conceptual framework. The framework is based on a generic design process model and consists of five parts: Conceptual design, Embodiment design, Detail design and Process planning and Process selection. 81 articles on DfAM are mapped onto the framework to provide, for the first time, a clear summary of the state of the art across the whole design process. Nine directions for the future of DfAM research are then proposed

Investigation of design for additive manufacturing in professional design practice

© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Additive Manufacturing (AM) technologies are widely adopted in design practice for prototyping. However, the extent to which practitioners are knowledgeable and experienced in designing components for series production using AM remains poorly understood. This study presents the results of an online survey aimed at uncovering this emerging design activity, with additional evidence provided by semi-structured interviews with 18 designers. One hundred ten practising designers responded. The majority of the respondents remain sceptical about the potential for AM as a process for series production, citing cost and technical capabilities as key barriers. Only 23 reported experience in designing components for series production using AM, with the majority of these designing parts to be produced from plastic. The survey revealed that these designers have developed their own ‘design rules’ based primarily on personal experience. These rules, however, tended to focus on ensuring ‘printability’ and did not provide support for taking advantage of the unique capabilities of AM processes. The designers tended to treat AM processes as a uniform set of production processes, and so the design rules they used were generic and not directed to the capabilities of specific AM processes

Aerodynamic Analysis of Simulated Heat Shield Recession for the Orion Command Module

The aerodynamic effects of the recession of the ablative thermal protection system for the Orion Command Module of the Crew Exploration Vehicle are important for the vehicle guidance. At the present time, the aerodynamic effects of recession being handled within the Orion aerodynamic database indirectly with an additional safety factor placed on the uncertainty bounds. This study is an initial attempt to quantify the effects for a particular set of recessed geometry shapes, in order to provide more rigorous analysis for managing recession effects within the aerodynamic database. The aerodynamic forces and moments for the baseline and recessed geometries were computed at several trajectory points using multiple CFD codes, both viscous and inviscid. The resulting aerodynamics for the baseline and recessed geometries were compared. The forces (lift, drag) show negligible differences between baseline and recessed geometries. Generally, the moments show a difference between baseline and recessed geometries that correlates with the maximum amount of recession of the geometry. The difference between the pitching moments for the baseline and recessed geometries increases as Mach number decreases (and the recession is greater), and reach a value of -0.0026 for the lowest Mach number. The change in trim angle of attack increases from approx. 0.5deg at M = 28.7 to approx. 1.3deg at M = 6, and is consistent with a previous analysis with a lower fidelity engineering tool. This correlation of the present results with the engineering tool results supports the continued use of the engineering tool for future work. The present analysis suggests there does not need to be an uncertainty due to recession in the Orion aerodynamic database for the force quantities. The magnitude of the change in pitching moment due to recession is large enough to warrant inclusion in the aerodynamic database. An increment in the uncertainty for pitching moment could be calculated from these results and included in the development of the aerodynamic database uncertainty for pitching moment

Adsorption of Toxic Metal Ions From Solution by Inactivated Cells of Larrea Tridentata Creosote Bush

Larrea tridentata (creosote bush) is a plant that grows abundantly in the desert environment. This desert plant has been found naturally growing in heavy-metal contaminated soils. Previous experiments showed that the inactivated biomass of creosote bush was able to adsorb Cu(II) ions from aqueous solutions. The copper-binding capacity of the bush biomass that grows in heavy-metal uncontaminated soils was higher than the biomass that grows in heavy-metal contaminated soils. Experiments were performed to determine the ability of creosote bush biomass (grown in heavy metal uncontaminated soils) to adsorb Pb(II), Cd(II), Zn(II), Cr(III), Cr(VI), and Ni(II) ions from aqueous solutions. Batch pH profile experiments for these metal ions showed that the metal ion binding was different for every metal tested but increased as the pH was raised from 2.0 to 6.0. The metal ion uptake by the roots, stems, and leaves was quite fast. Binding capacity experiments showed a more significant binding capacity for lead(II) and chromium(III) ions and in general, the leaves bound more metal ions than the stems and roots. A great portion of the metal ions adsorbed by the creosote’s roots, stems, and leaves was desorbed by treatment with 0.1 M HCl (up to 99% in some cases). Biomass of creosote bush may prove to be useful to remove and recover metal ions from contaminated waters

High School English Teachers' Perceptions Regarding Standardized Testing and College Readiness

The purpose of this phenomenological study was to explore English high school teachers’ perceptions regarding standardized testing and college readiness. This study provided a thorough investigation of the lived experiences and perceptions of English high school teachers’ ability to prepare students for standardized testing, and their ability to prepare students to be college ready. Purposeful sampling was used to select eight participants to participate in individual interviews. Five themes emerged from the data. Professional development for standardized testing and college readiness played an important role in how teachers prepare students for standardized testing while preparing them for college. Preparing students for standardized tests and college contributed to their comfort level. Student and teacher performance on standardized tests and in the classroom are directly impacted by how students perform on their tests. The curriculum used to teach students is all geared towards standardized testing. Lastly, teaching in the pandemic was a big concern for the participants as they will prepare students for standardized testing and college through virtual learning