Heavy-Atom Tunneling in the Covalent/Dative Bond Complexation of Cyclo[18]carbon–piperidine

Recent quantum chemical computations demonstrated the electron-acceptance behavior of this highly reactive cyclo[18]carbon (C18) ring with piperidine (pip). The C18–pip complexation exhibited a double-well potential along the N–C reaction coordinate, forming a van der Waals (vdW) adduct and a more stable, strong covalent/dative bond (DB) complex by overcoming a low activation barrier. By means of direct dynamical computations using canonical variational transition state theory (CVT), including the small-curvature tunneling (SCT), we show the conspicuous role of heavy atom quantum mechanical tunneling (QMT) in the transformation of vdW to DB complex in the solvent phase near absolute zero. Below 50 K, the reaction is entirely driven by QMT, while at 30 K, the QMT rate is too rapid (kT ~ 0.02 s-1), corresponding to a half-life time of 38 s, indicating that the vdW adduct will have a fleeting existence. We also explored the QMT rates of other cyclo[n]carbon–pip systems. This study sheds light on the decisive role of QMT in the covalent/DB formation of the C18–pip complex at cryogenic temperatures.

Viscosity model of deep eutectic solvents from group contribution method

In this work, based on mathematical model inspired by transition state theory, the group contribution (GC) method is used to predict the viscosity of DESs. The model is constrained by Eyring rate theory and hard sphere free volume theory. A dataset of 2229 experimental measurements of the viscosity of 183 DESs from literature is used for determining the model parameters and subsequent verification of the model. The rules introduced by this model are simple and easy to understand. The results show that the proposed model is able to predict the DESs viscosity with very high accuracy, i.e., with an average absolute relative deviation of 8.12% over the training set and 8.64% over the test set, using only temperature and composition as inputs. The maximum absolute relative deviation is 34.63%. Therefore, the as-proposed model can be considered a highly reliable tool for predicting DESs viscosity when experimental data are absent.

Virtual-Ligand-Assisted Screening Strategy to Discover Enabling Ligands for Transition Metal Catalysis

The ligand screening process, in which an optimal ligand for a reaction of interest is identified from an enormous and diverse set of candidate molecules, is of particular importance in the development of transition metal catalysis. Conventionally, this process has been performed by experimental trial-and-error cycles, which require significant time and resources. Herein, we report a novel strategy called “virtual-ligand-assisted (VLA) screening” that enables practical in silico ligand screening based on the transition state theory. We developed a virtual ligand, PCl*3, which parameterizes both the electronic and steric effects of monodentate phosphorus(III) ligands in quantum chemical calculations, and used it to assess how these effects perturb the energy profile of a reaction. This parameter-based ligand screening approach allowed us to identify the optimal electronic and steric effects for a reaction of interest, thereby affording guiding principles for rational ligand design. The VLA screening strategy was demonstrated for the selectivity-determining step of the rhodium-catalyzed hydroformylation of a terminal olefin, and phosphorus(III) ligands with potentially high linear or branched selectivities were designed. These findings indicate that VLA screening is a promising approach for streamlining the ligand screening process.

Investigation on the passivation, band alignment, gate charge, and mobility degradation of the Ge MOSFET with a GeO x /Al2O3 gate stack by ozone oxidation

Ge has been an alternative channel material for the performance enhancement of complementary metal–oxide–semiconductor (CMOS) technology applications because of its high carrier mobility and superior compatibility with Si CMOS technology. The gate structure plays a key role on the electrical property. In this paper, the property of Ge MOSFET with Al2O3/GeO x /Ge stack by ozone oxidation is reviewed. The GeO x passivation mechanism by ozone oxidation and band alignment of Al2O3/GeO x /Ge stack is described. In addition, the charge distribution in the gate stack and remote Coulomb scattering on carrier mobility is also presented. The surface passivation is mainly attributed to the high oxidation state of Ge. The energy band alignment is well explained by the gap state theory. The charge distribution is quantitatively characterized and it is found that the gate charges make a great degradation on carrier mobility. These investigations help to provide an impressive understanding and a possible instructive method to improve the performance of Ge devices.

Violent Extremism and the Politics of Education in Pakistan

Pakistan is depicted as a victim as well as a sponsor of terrorism. The reason behind this characterisation is that Pakistan, since its inception in 1947, has experienced multifaceted violence, ranging from ethnic insurgencies to sectarian violence. At the same time, it has been blamed for fomenting violence in its neighbours. On the one hand, there have been anti-terrorism laws in place since the late 1990s; on the other, there is an Islamised public sphere that provides fecund soil for violent extremists to thrive. The questions to be addressed here are: What kinds of anti-terrorism laws exist in Pakistan and how effective are they against terrorism? What is the role of the state-managed curriculum in providing a conducive environment for the growth of violent extremism? This research appeals to the “garrison state” theory, which explains how “the specialists on violence” control every aspect of the state, complemented by the concept of “fragmented hegemony,” which explains how the seemingly corrupt multiple sites of power help the state maintain its hegemony over society.

POLITIK EKOLOGI KEHUTANAN: KEBIJAKAN HUTAN TANAMAN INDUSTRI DI SAMBELIA, LOMBOK TIMUR

Ecological politics rely solely on economic interest. Development and the environment have a complicated correlation. The industrial plantation forest policy aims to ensure that the economic benefit goes hand in hand with the sustainability demand. Ironically, this policy triggers a conflict between local communities and corporations as the holder of forest concession rights. The concession is practically established due to merely economic interest aligned with the extractive industry of tobacco in Lombok. The plantation is aimed as the supporting source for the tobacco industry since it requires specific woods to roast the tobacco. The study refers to utilizes instrumental state theory and deep ecology perspective to identify how the policy was made for the capital and tobacco capital benefits, while the sustainability objective is left behind. The study shows not only how the concession sparked ironic economic development, but also how the liberal environmentalism approach in industrial forest plantation policy has failed to gain its objective. The economic potential of tobacco in Lombok is the main determinant in industrial forest plantation policy that changes community forests into private forests. In the end, the policy was strategically implemented to sustain production and strengthen corporation monopoly over forests.

Four Asian Tigers' Political and Economic Development Revisited 1998-2017: From the Perspective of National Identity

Developmental state used to be and is still regarded as a very practical theory to explain why Four Asian Tigers-Taiwan, South Korea, Hong Kong, and Singapore enjoyed almost averagely double-digit economic growth rate each year from 1970 to 1990 as well as East Asian economic development. However, developmental state theory couldn’t tell why South Korea and Singapore’s economic development had done much better than Taiwan and Hong Kong’s in terms of GDP per capita after 2003 and 2004 respectively. The aim of the study is trying to use national identity perspective to explain why it happens like this, since Four Asian Tigers’ economic development more or less was troubled by national identity issue. The major difference between these two groups is that South Korea and Singapore have done better in dealing with national identity issue than Taiwan and Hong Kong.

Hot atom chemistry: oxygen at stepped platinum surfaces

It is a paradigm in chemistry that chemical reaction are mainly governed by thermodynamics. Within this assumption, reaction rates can be derived from transition state theory which requires a quasi-equilibrium between reactants and activated transition state complexes that is achieved through friction. However, to reach thermal equilibrium through friction takes some time. Here we show, based on ab initio molecular dynamics simulations of the interaction of molecular oxygen with stepped Pt surfaces, that chemical reactions in heterogeneous catalysis can occur in a non-equilibrium fashion when the excess kinetic energy upon entering the potential well of a reaction intermediate is large enough.

The Limitation of the Combination of Transition State Theory and Thermodynamics for the Reactions of Proteins and Nucleic Acids

When a reaction is accompanied by a change with the speed close to or slower than the reaction rate, a circulating reaction flow can exist among the reaction states in the macroscopic stationary state. If the accompanying change were at equilibrium in the timescale of the relevant reaction, the transition-state theory would hold to eliminate the flow.