Inside and outside N-bridge cavity systems: Evidence for syn- and anti-atropisomers in scaffolds containing two N-benzoyl 7-azanorbornane units

Alkene and aziridine reagents containing N-benzoyl 7-azanorbornane components have been prepared and used to construct [n] polynorbornanes in a block building protocol. The presence of syn- and anti-atropisomers involving the restricted rotation of the N-COPh bridge was established by 1H NMR spectroscopy in an NNN-[3]polynorbornane 4 (outside bridges) whereas the anti-conformer dominated in a cavity NCOCOCN-[7]isopolynorbornane 8 (inside bridges, X-ray confirmation) prepared by a dual 1,3-dipolar addition of an acute-angled norbornene 6 with a hexacyclic bis-epoxide 7.</p

The N,O-bridged sesquinorbornadienes: a testing ground for establishing the superiority of N-Z Pyrrole over furan as a dienofuge n retro-diels-alder reactions

 N-R pyrroles (R=H, Z, COPh but not Bn, TMS) 6 add selectively at rt to the substituted π-bond of 2,3-bis(trifluoromethyl)-7-oxanorbornadiene 7 under high pressure (14 kbar) to form exclusively the syn-facial N,O-sesquinorbornadienes 8; at higher temperatures the thermodynamic stereoisomers 10,11 are produced by cycloreversion and reaction at the unsubstituted π-bond. The exclusive loss of N-Z pyrrole from the N-Z derivative of 8 demonstrated the superior dienofugacity of N-Z pyrrole over furan; kinetic studies showed that the activation energy for this fragmentation was 34.7 kcal mol−1. This selectivity is in accord with theory (AM1, ab initio). </p

Tetrakis-(N-pyrrolyl)methane : structurally important member of the C(NR2)4 family

"It has been predicted that the polymorphic forms of carbon nitride are harder than diamond [1], and this auspicious speculation has prompted huge efforts to reliably prepare C3N4 [2]. Recently, there have been a number reports in surface science literature about the existence of carbon nitride phases as thin layers [3]. Carbon nitride is expected to have each nitrogen atom connected to three carbon atoms and each carbon atom connected to four nitrogen atoms. Although tertiary amines (NC3) are very common, compounds containing C(NR2)4 units are rare in organic chemistry, and very few examples have appeared in the literature (e.g., structures 1 [4], 2 [5], and 3 [6], Fig. 1). In this communication, we describe an interesting member of this class, namely tetrakis-(N-pyrrolyl)methane 4, comparable with the time-honored tetraphenyl analogue and prototype for a large family of tetrakis-N-[5-ring]heteroaryl methanes of which tetrakis-N-pyrazolyl methane 2 [5] appears to be the only other known member." --Introduction

Position-addressable nano-scaffolds. I. The preparation of N,O-, N,C- and N,N-bridged sesquinorbornadiene succinimides as compact, highly functionalized addressable building blocks

Succinimide-functionalized N,O-,N,C-, and N,N- bridged benzol[2] polynorbornanes (benzosesquinorboradienes) are reported for the first time and are prepared by the cycloaddition of either five-membered cyclie 1,3-diennes onto N-subsisted benzo-7-azanorboradienomaleimides or N-subsituted isoindoles onto the appropriate norbornadienomaleimides. These products containan end-fused norbornen (or a 7-substituted relative) and have been designed to act as alkene BLOCKs for the production of nano-scaffold with up to six addressable sites supplied byeach norbornrnr unit. The N-bridges in these BLOCKs (and their coupled products) allow N-substituent mobilityby invertomerization of the sp3 nitrogen whereas the N-substituents on the succinimides are attached to an sp2 nitrogen atom and remain static. Preferred invertomer geometry can be determined using molecular modelling

Neighbouring group participation in N-Methoxymethyl 7-Azanorbornanes 1

Abstrac

Micro learning adaptation in MOOC: A Software as a Service and a personalized learner model

Micro learning is gradually becoming a common learning mode in massive open online course learning (MOOC). We illustrate a research strategy to formalize and customize micro learning resources in order to meet personal demands at the real time. This smart micro learning environment can be organized by a Software as a Service (SaaS) we newly designed, in which educational data mining technique is mainly employed to understand learners learning behaviors and recognize learning resource features in order to identify potential micro learning solutions. A learner model with regards to internal and external factors is also proposed for personalization in micro MOOC learning context

A framework of MLaaS for facilitating adaptive micro learning through open education resources in mobile environment

© 2017, IGI Global. Micro learning becomes popular in online open learning and it is effective and helpful for learning in mobile environment. However, the delivery of open education resources (OERs) is scarcely supported by the current online systems. In this research, the authors introduce an approach to bridge the gap by providing adaptive micro open education resources for individual learners to carry out learning activities in a short time span. They propose a framework for micro learning resource customization and a personalized learner model, which are supported by education data mining (EDM) and learning analysis (LA). A service-oriented architecture for Micro Learning as a Service (MLaaS) is designed to integrate all necessary procedures together as a complete Service for delivering micro OERs, providing a platform for resource sharing and exchanging in peer-to-peer learning environment. Working principle of a key step, namely the computational decision-making of micro OER adaptation, is also introduced

MLaaS : a cloud system for mobile micro learning in MOOC

Mobile learning in massive open online course (MOOC) differs evidently from its traditional ways as it relies more on collaboration and becomes fragmented. We introduce a cloud-based system which can organize learners into a better teamwork context and customize micro learning resources in order to meet personal demands in real time. Particularly, a smart micro learning environment can be built by a newly designed SaaS, in which educational data mining techniques are mainly employed to understand learners' behaviors and recognize learning resource features

Epigallocatechin gallate (EGCG) decorating soybean seed ferritin as a rutin nanocarrier with prolonged release property in the gastrointestinal tract

The instability and low bioavailability of polyphenols limit their applications in food industries. In this study, epigallocatechin gallate (EGCG) and soybean seed ferritin deprived of iron (apoSSF) were fabricated as a combined double shell material to encapsulate rutin flavonoid molecules. Firstly, due to the reversible assembly characteristics of phytoferritin, rutin was successfully encapsulated within apoSSF to form a ferritin-rutin complex (FR) with an average molar ratio of 28.2: 1 (rutin/ferritin). The encapsulation efficiency and loading capacity of rutin were 18.80 and 2.98 %, respectively. EGCG was then bound to FR to form FR-EGCG composites (FRE), and the binding number of EGCG was 27.30 ± 0.68 with a binding constant K of (2.65 ± 0.11) × 10(4) M(-1). Furthermore, FRE exhibited improved rutin stability, and displayed prolonged release of rutin in simulated gastrointestinal tract fluid, which may be attributed to the external attachment of EGCG to the ferritin cage potentially reducing enzymolysis in GI fluid. In summary, this work demonstrates a novel nanocarrier for stabilization and sustained release of bioactive polyphenols

Towards bringing adaptive micro learning into MOOC courses

In this paper we illustrate a proposal with regard to providing learners adaptive micro learning experiences, which can be fulfilled within fragmented time pieces. The framework of our system is demonstrated, while it aims to deliver customized micro learning contents taking into account learners' specific demands, learning styles, preference and context