2-{(1S,2S,4aR,8R,8aR)-8-Hy­droxy-4a,8-dimethyl-1-[(2E)-2-methyl­but-2-eno­yl­oxy]perhydro­naphthalen-2-yl}acrylic acid from Sclerorhachis platyrachis

The eudesmane-type terpenoid, C20H30O5, isolated from Sclerorhachis platyrachis, has a deca­lin skeleton whose six-membered rings adopt chair conformations. The two methyl substituents occupy axial positions, whereas the other three substituents occupy equatorial positions. The hy­droxy group is an intra­molecular hydrogen-bond donor to the single-bond ester O atom; adjacent mol­ecules are linked through the carb­oxy­lic acid interacting with the hydroxyl group, forming a hydrogen-bonded chain running along the c axis

Productivity improvement of transmission electron microscopes - A case study

This paper aims to improve the performance of Transmission Electron Microscopes (TEM) used in asbestos detection processes in a business context. Failure Modes and Effects Analysis (FMEA) were studied, identifying the critical failure modes, proposing risk reduction measures and changing maintenance practices based on the Reliability Centered Maintenance strategy. In the elaboration of the FMEA it was evident the lack of data and poor information quality regarding the reliability and maintenance of TEM. These circumstances led to the implementation of training projects to standardize operations and to the development of a software application for data collection and reports generation with relevant performance indicators (Costs, Mean Down Time, Overall Equipment Effectiveness, …) to support operators tasks and decision-making. The approach followed and the tools developed allowed monitoring TEM productivity and maintenance performance. As a result, more informed decisions can be made that will lead to improved performance of TEM.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020

Characterization of oils from Duranta repens

The knowledge of the chemical composition of unpopular sources of edible oils has become paramount to supplement the usage of widely known vegetable oils. In this study, the gas chromatographic quantification of fatty acids and phytochemicals was carried out, and the physicochemical and micronutrient composition of Duranta repens leaf and seed oil were evaluated using standard methods. The leaf oils contained significantly higher (p  oleic > myristic > stearic > capric > linoleic > lauric > palmitoleic for the seed oil, while for the leaf oil linoleic > palmitoleic > oleic > stearic > palmitic > myristic > capric > lauric > myristoleic. The major phytochemical constituents of the seed oils were catechin (68.12 ug/ml), saponin (44.03 ug/ml), rutin (32.89 ug/ml), linamarin (22.66 ug/ml) and tannins (19.62 ug/ml), while kaempherol (84.05 ug/ml), rutin (62.26 ug/ml) and saponins (45.63 ug/ml) were mostly predominant in the leaf oil. Spartein, anthocyanins and phytates were among the least phytochemicals in composition, for both samples. These chemical properties evaluated, suggest that Duranta repens seed oil is more suitable for industrial and therapeutic purposes

Recent Applications of Acyclic (Diene)iron Complexes and (Dienyl)iron Cations in Organic Synthesis

Complexation of (tricarbonyl)iron to an acyclic diene serves to protect the ligand against oxidation, reduction, and cycloaddition reactions, whereas the steric bulk of this adjunct serves to direct the approaches of reagents to unsaturated groups attached to the diene onto the face opposite to iron. Furthermore, the Fe(CO)3 moiety can serve to stabilize carbocation centers adjacent to the diene (i.e. pentadienyl-iron cations). Recent applications of these reactivities to the synthesis of polyene-, cyclopropane-, cycloheptadiene-, and cyclohexenone-containing natural products or analogues are presented

1α,25(OH)2-3-Epi-Vitamin D3, a Natural Physiological Metabolite of Vitamin D3: Its Synthesis, Biological Activity and Crystal Structure with Its Receptor

Background: The 1 alpha,25-dihydroxy-3-epi-vitamin-D(3) (1 alpha,25(OH)(2)-3-epi-D(3)), a natural metabolite of the seco-steroid vitamin D(3), exerts its biological activity through binding to its cognate vitamin D nuclear receptor (VDR), a ligand dependent transcription regulator. In vivo action of 1 alpha,25(OH)(2)-3-epi-D(3) is tissue-specific and exhibits lowest calcemic effect compared to that induced by 1 alpha,25(OH)(2)D(3). To further unveil the structural mechanism and structure-activity relationships of 1 alpha,25(OH)(2)-3-epi-D3 and its receptor complex, we characterized some of its in vitro biological properties and solved its crystal structure complexed with human VDR ligand-binding domain (LBD). Methodology/Principal Findings: In the present study, we report the more effective synthesis with fewer steps that provides higher yield of the 3-epimer of the 1 alpha,25(OH)(2)D(3). We solved the crystal structure of its complex with the human VDR-LBD and found that this natural metabolite displays specific adaptation of the ligand-binding pocket, as the 3-epimer maintains the number of hydrogen bonds by an alternative water-mediated interaction to compensate the abolished interaction with Ser278. In addition, the biological activity of the 1 alpha,25(OH)(2)-3-epi-D(3) in primary human keratinocytes and biochemical properties are comparable to 1 alpha,25(OH)(2)D(3). Conclusions/Significance: The physiological role of this pathway as the specific biological action of the 3-epimer remains unclear. However, its high metabolic stability together with its significant biologic activity makes this natural metabolite an interesting ligand for clinical applications. Our new findings contribute to a better understanding at molecular level how natural metabolites of 1 alpha,25(OH)(2)D(3) lead to significant activity in biological systems and we conclude that the C3-epimerization pathway produces an active metabolite with similar biochemical and biological properties to those of the 1 alpha,25(OH)(2)D(3)