Self‐Assembly of π‐Conjugated Amphiphiles: Free Standing,Ordered Sheets with Enhanced Mobility

Oligo(p‐phenylenevinylenes) (OPVs) with amphiphilic character are synthesized and their self‐assembly characteristics studied. Careful studies point at two morphologically different states of assemblies, with one being two dimensional sheets and the other as rolled tubes. This is also the first time that self‐assembled sheets are achieved for OPVs. Morphological and photo‐physical studies reveal a unique aggregate to aggregate transition between rolled tubes and two dimensional sheets, which is outlined as a more thermodynamic aggregate. The thermodynamic aggregate (2D sheet) is better ordered and consists of chromophores that are better excitonically coupled. The mobilities of these aggregates are also studied for a field effect transistor device and as expected sheets supersede rolled tubes by a couple of orders. More interestingly, the mobility values obtained for the well ordered chromophores in sheets is three orders higher than any other self‐assembled OPV previously reported. It is hypothesized that the better π interactions enforced by the amphiphilic design and the resultant supramolecular organization is a prime factor for such a remarkable rise in mobilities.     

Rapid mixing chemical oxidative polymerization: an easy route to prepare PANI coated small-diameter CNTs/PANI nanofibres composite thin film

Composite thin film containing polyaniline (PANI) coated small diameter carbon nanotubes (SDCNTs)/PANI nanofibres (NFs) has been prepared using an easy in situ rapid mixing chemical oxidative polymerization method. SDCNTs thin film was obtained using thermal chemical vapour deposition method in a separate experiment, whilst PANI NFs are formed in situ during the synthesis of composite. In the composite, PANI coated SDCNTs are uniformly distributed among PANI NFs. The presence of SDCNTs during the composite synthesis does not influence the nucleation and growth of PANI NFs. Raman analysis shows a good interaction between PANI and SDCNTs. Room temperature d.c. electrical sheet resistance of SDCNTs/PANI NFs composite thin film surface is three orders lesser than that of PANI NFs thin film (PANI NFs have the same morphology as in the composite) synthesized using the same method but without the presence of SDCNTs.     

Catalytic effect of bis (cyclopentadienyl) nickel II on the improvement of the hydrogenation-dehydrogenation of Mg-MgH2 system

Bis(cyclopentadienyl) nickel II is one of the best precursors of nickel catalyst which remarkably improved the hydrogen absorption-desorption of Mg–MgH₂ system. The X-ray photoelectron spectroscopy (XPS) and Furrier Transformed Infrared Spectroscopy (FTIR) analyses revealed that bis (cyclopentadienyl) nickel II decomposed into metallic nickel during ball milling with MgH₂. The nickel thus formed has homogeneously doped over the Mg - MgH₂ surface. The Ni-doped Mg-MgH₂ have shown the excellent catalytic effect on hydrogen absorption-desorption. The catalyzed MgH₂ could desorb hydrogen below 225 °C (T_onset) under Ar flow, and absorb hydrogen at 50 °C under 1.5 MPa H₂ pressure. The hydrogen absorption-desorption temperatures are remarkably decreased as compared to the uncatalyzed Mg-MgH₂ system under the identical experimental conditions.     

Development of Multi Micro Manipulation System Using IPMC Micro Grippers

This paper presents a new design of multi micro manipulation system using ionic polymer metal composite (IPMC) micro grippers for robotic micro assembly where IPMC is used as a light weight actuator for developing the micro grippers. It has the potential of large displacement, low mass force generation and misalignment compensation ability during micro manipulation. These capabilities are utilized for handling of miniature parts like pegs. The analysis of IPMC micro gripper and manipulator are carried out for developing a multi micro manipulation system that can handle pegs in micro assembly operation for shifting one to another hole position in a large work space (100 mm × 100 mm). By developing a prototype, it is demonstrated that IPMC based micro grippers are capable of handling the peg-in-hole assembly tasks in a multi micro manipulation system.     

A grey approach for forecasting in a supply chain during intermittentdisruptions

The supply chains today have become vulnerable to frequent disruptions, and with continuing emphasis on efficiency, lacks robustness to deal with them. A part of the solution lies in forecasting the disruption beforehand and the other part in knowing which policies will suit such disrupted conditions best. Accurate and immediate forecasts are a must in a supply chain and hence play a huge role in stabilizing. This study compares the performance of three established forecasting methods (moving average, weighted moving average and exponential smoothing) as well as grey prediction method, during disruptions and stable situations. The experiments are performed in the form of discrete event simulation, on a four stage beer game settings. The results show that moving average and weighted moving average methods become incompetent during disruptions, and are useful only during stable times, when the demand hovers around a predefined mean value. Exponential smoothing and grey method seems to give better results during disruptions and also during stable times in upstream tiers. Grey prediction method in particular is the best method when the disruption frequency is high and also when the disruption impact is gradual rather than sudden.     

Fabrication and Circuit Modeling of NMOS Inverter Based on Quantum Dot Gate Field-Effect Transistors

This paper presents the fabrication of a negative-channel metal–oxide–semiconductor (NMOS) inverter based on quantum dot gate field-effect transistors (QDG-FETs). A QDG-FET produces one intermediate state in its transfer characteristic. NMOS inverters based on a QDG-FET produce three states in their transfer characteristic. The generation of the third state in the inverter characteristic makes this a promising circuit element for multivalued logic implementation. A circuit simulation result based on the Berkley simulation (BSIM) circuit model of the QDG-FET is also presented in this paper, predicting the fabricated device characteristic.     

Non-dendritic Structural Changes in Al–7Si Alloy Cast Through Rapid Slurry Formation (RSF) Process

Rapid slurry formation (RSF) is a semi-solid metal forming technique, which is based on a so-called solid enthalpy exchange material. The beauty of the process is that the slurry is controlled by relative added amounts of the alloy system used. It is not necessary to accurately control the heat flux to surrounding media such as, crucible or mould. In the present investigation 15?% solid fraction in Al?C7Si alloy slurry has been produced by RSF method. The slurry so prepared was cast in gravity die cast mould with water cooling arrangement. Thus ingot of size 30?cm?×?5?cm?×?2.5?cm could be produced. The microstructure showed rosette and globular type ??-Al morphology. Tensile properties evaluated were higher than as cast Al?C7Si alloy. During slurry formation coarsening of particles was experimentally investigated and also theoretically described by Lifshitz-Slyozov-Wagner (LSW) theory and convective mass flow equations.