Quantitative Current–Voltage Characteristics in Molecular Junctions from First Principles

Darancet, Pierre,Widawsky, Jonathan R.,Choi, Hyoung Joon,Venkataraman, Latha,Neaton, Jeffrey B. American Chemical Society 2012 NANO LETTERS Vol.12 No.12

<P>Using self-energy-corrected density functional theory (DFT) and a coherent scattering-state approach, we explain current–voltage (IV) measurements of four pyridine-Au and amine-Au linked molecular junctions with quantitative accuracy. Parameter-free many-electron self-energy corrections to DFT Kohn–Sham eigenvalues are demonstrated to lead to excellent agreement with experiments at finite bias, improving upon order-of-magnitude errors in currents obtained with standard DFT approaches. We further propose an approximate route for prediction of quantitative IV characteristics for both symmetric and asymmetric molecular junctions based on linear response theory and knowledge of the Stark shifts of junction resonance energies. Our work demonstrates that a quantitative, computationally inexpensive description of coherent transport in molecular junctions is readily achievable, enabling new understanding and control of charge transport properties of molecular-scale interfaces at large bias voltages.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-12/nl3033137/production/images/medium/nl-2012-033137_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl3033137'>ACS Electronic Supporting Info</A></P>

Control of Single-Molecule Junction Conductance of Porphyrins via a Transition-Metal Center

Liu, Zhen-Fei,Wei, Sujun,Yoon, Hongsik,Adak, Olgun,Ponce, Ingrid,Jiang, Yivan,Jang, Woo-Dong,Campos, Luis M.,Venkataraman, Latha,Neaton, Jeffrey B. American Chemical Society 2014 NANO LETTERS Vol.14 No.9

<P>Using scanning tunneling microscope break-junction experiments and a new first-principles approach to conductance calculations, we report and explain low-bias charge transport behavior of four types of metal–porphyrin–gold molecular junctions. A nonequilibrium Green’s function approach based on self-energy corrected density functional theory and optimally tuned range-separated hybrid functionals is developed and used to understand experimental trends quantitatively. Importantly, due to the localized d states of the porphyrin molecules, hybrid functionals are essential for explaining measurements; standard semilocal functionals yield qualitatively incorrect results. Comparing directly with experiments, we show that the conductance can change by nearly a factor of 2 when different metal cations are used, counter to trends expected from gas-phase ionization energies which are relatively unchanged with the metal center. Our work explains the sensitivity of the porphyrin conductance with the metal center via a detailed and quantitative portrait of the interface electronic structure and provides a new framework for understanding transport quantitatively in complex junctions involving molecules with localized d states of relevance to light harvesting and energy conversion.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-9/nl5025062/production/images/medium/nl-2014-025062_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5025062'>ACS Electronic Supporting Info</A></P>

Morphology and topography of the parietal emissary foramina in South Indians: an anatomical study

B. V. Murlimanju,Vasudha V. Saralaya,M. S. Somesh,Latha V. Prabhu,Ashwin Krishnamurthy,Ganesh Kumar Chettiar,Mangala M. Pai 대한해부학회 2015 Anatomy & Cell Biology Vol.48 No.4

The objectives of the present study were to study the prevalence of the parietal emissary vein in adult South Indian population and to study the distance of foramen from the sagittal suture. There were 58 adult human skulls in the present study which were available at the anatomy department of our institution. The study included 116 parietal bones which have been observed macroscopically for the number, prevalence and topography of the emissary foramen. The emissary foramen was present in 83 parietal bones (71.5%) of the present study. It was present at the junction between the middle 1/3 and posterior 1/3 region of the parietal bone. The foramen was observed solitary in 73 parietal bones (62.9%), double in 8 bones (6.9%), and triple in 2 parietal bones (1.7%). The foramen was not observed in 33 parietal bones (28.4%). The bilateral absence of parietal emissary foramen was seen in 7 skulls (12.1%). It was absent unilaterally in 19 skulls (32.7%). The accessory foramina were seen in only 8 skulls (13.8%). The mean distance of the foramen from the sagittal suture was 6.7±2.9 mm and 6.8±2.8 mm on the right and left sides respectively. The prevalence of parietal emissary vein in the present study was 71.5%. The present study has observed important data about the morphology and morphometry of the parietal emissary vein in South Indian population. The identification of parietal emissary veins and accessory veins is important in the operation room to prevent the blood loss.

Mastoid emissary foramina: an anatomical morphological study with discussion on their evolutionary and clinical implications

B V Murlimanju,Ganesh Kumar Chettiar,M D Prameela,Mamatha Tonse,Naveen Kumar,Vasudha V Saralaya,Latha V Prabhu 대한해부학회 2014 Anatomy & Cell Biology Vol.47 No.3

The identification of mastoidal emissary veins is of importance in the neurosurgical practice to diagnose abnormal and normal structures. In the present study, the objectives were to estimate the prevalence rate of mastoidal emissary foramina in the temporal bones of the adult skull and to study their number and morphology. The present study included 48 adult human skulls which were obtained from the gross anatomy laboratory of our institution. The mastoid parts of 96 temporal bones were macroscopically observed for the prevalence, number and morphology of the emissary foramina. It is observed that, the mastoidal emissary foramen was present in 88 temporal bones (91.7%) of our specimens. The foramen was observed single in 60 temporal bones (62.5%), double in 22 bones (22.9%), and triple in 6 temporal bones (6.2%). The mastoidal emissary foramen was absent in 8 (8.3%) temporal bones. The foramen was bilaterally absent in 3 (3.1%) skulls. It was unilaterally absent in 2 (2.1%) skulls and both were on the left side. The mastoidal emissary vein is prevalent in a large number (91.7%) of cases. It was observed that the accessory mastoidal emissary foramina were present in 29.1% of cases. Recognition of the mastoid emissary veins and accessory mastoid emissary veins during the otologic surgery is critical to avoid the significant bleeding. In the neurosurgical practice, the knowledge is important due to variability in the number of mastoidal emissary veins and their connection to the venous sinuses.

Multiple Performance Optimization in Machining of GFRP Composites by a PCD Tool using Non-dominated Sorting Genetic Algorithm (NSGA-II)

K. Palanikumar,B. Latha,V. S. Senthilkumar,R. Karthikeyan 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.2

Optimization of cutting parameters is important to achieving high quality in the machining process, especially where more complex multiple performance optimization is required. The present investigation focuses on the multiple performance optimization on machining characteristics of glass fiber reinforced plastic (GFRP) composites. The cutting parameters used for the experiments, which were carried out according to Taguchi’s L27, 3-level orthogonal array, were cutting speed, feed and depth of cut. Statistical models based on secondorder polynomial equations were developed for the different responses. The Non-dominated Sorting Genetic Algorithm (NSGA-II) tool was used to optimize the cutting conditions, yielding a non-dominated solution set that is reported here. Optimization of cutting parameters is important to achieving high quality in the machining process, especially where more complex multiple performance optimization is required. The present investigation focuses on the multiple performance optimization on machining characteristics of glass fiber reinforced plastic (GFRP) composites. The cutting parameters used for the experiments, which were carried out according to Taguchi’s L27, 3-level orthogonal array, were cutting speed, feed and depth of cut. Statistical models based on secondorder polynomial equations were developed for the different responses. The Non-dominated Sorting Genetic Algorithm (NSGA-II) tool was used to optimize the cutting conditions, yielding a non-dominated solution set that is reported here.

Morphological study of styloid process of the temporal bone and its clinical implications

Rajanigandha Vadgaonkar,B. V. Murlimanju,Latha V. Prabhu,Rajalakshmi Rai,Mangala M. Pai,Mamatha Tonse,P. J. Jiji 대한해부학회 2015 Anatomy & Cell Biology Vol.48 No.3

The objective of this study was to study the morphometry of the styloid process of temporal bone and prevalence of elongated styloid process. The morphology of elongated styloid process along with its embryological and clinical importance are discussed. The present study included 110 human dry skulls which were procured from the bone collections of the department of anatomy. The styloid process was observed macroscopically on both sides of all the skulls, the elongations if any were noted. All the styloids were measured for their length, thickness at different levels and interstyloid distance at various levels. Out of 110 specimens, only 5 skulls (4.5%) exhibited the elongated styloid process. Among them, 3 skulls (2.7%) had unilateral elongation and 2 skulls (1.8%) had bilateral elongation of the styloid process. The mean length of the styloid process was 17.8±9.3 mm and 18.2±5.6 mm for the right and left sides, respectively. The prevalence of elongated styloid process in the present study was 4.5%. The clinical anatomy of this congenital variant is important to the neurosurgeon and radiologist, while interpreting the computed tomogram and magnetic resonance image scans. The morphological knowledge of elongated styloid process is clinically important since the course of the vertebral artery may be distorted in such situations.

Reduced-order thermal behavior of universal motor-driven domestic food mixers/grinders using AC and DC supplies

Mercy, A.,Umamaheswari, B.,Latha, K. The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.9

This paper presents an improvement in the thermal performance of universal motor, which improves the efficiency and increases the life of the motor. Excessive heating in the winding can lead to an insulation failure of a universal motor and reduce the life of a food mixer. Hence, to avoid hot spots in machine parts and obtain a homogenous temperature distribution, it is necessary to take the thermal limits into consideration. To monitor temperature increase, a lumped parameter thermal model is designed with 12 nodes for a food mixer driven by a universal motor. This paper proposes a reduced-order thermal model for a universal motor used in food mixers to monitor its thermal behavior. In this paper, a 12th-order model is reduced to a 5th-order model using a balanced truncation reduction method. The reduced-order model is validated through simulation and experimental results by comparing its response with a full-order model. A thermal analysis is carried out using AC and DC supplies along with experimentation. It can be seen that when the universal motor is operated with a DC supply, its thermal performance is improved, which increases the life of the machine. This results in energy savings, since the efficiency of the universal motor is increased when it is operated using the DC supply.

Evaluation of Soil Health, Sustainability Index, Carbon Sequestration Potential and Productivity under Organic and Conventional Rice (oryza Sativa L.) Production Systems

Surekha Kuchi,P C Latha,K V Rao,R M Kumar,B C Viraktamath 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Investigation and analysis of surface roughness in machining carbon fiber reinforced polymer composites using artificial intelligence techniques

Rajasekaran T.,Palanikumar K.,Latha B. 한국탄소학회 2022 Carbon Letters Vol.32 No.2

Carbon fiber and its composites are increasingly used in many fields including defence, military, and allied industries. Also, surface quality is given due importance, as mating parts are used in machineries for their functioning. In this work, the turning process is considered for Carbon Fiber Reinforced Polymer (CFRP) composites by varying three important cutting variables: cutting speed, feed, and depth of cut. Correspondingly, the surface roughness is measured after the completion of turning operation. As well, a prediction model is created using different fuzzy logic membership function and Levenberg–Marquardt algorithm (LMA) in artificial intelligence. Later, the surface roughness values from the developed models are compared against the experimental values for its correlation and effectiveness in using different membership functions of fuzzy logic and ANN. Thus, the experimental results are analyzed using the effect graphs and it is presented in detail.

Optimization of Machining Parameters in Turning GFRP Composites Using a Carbide (K10) Tool Based on the Taguchi Method with Fuzzy Logics

K. Palanikumar,L. Karunamoorthy,R. Karthikeyan,B. Latha 대한금속ᆞ재료학회 2006 METALS AND MATERIALS International Vol.12 No.6