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Here, we extend the system energy prediction approach used in the force field FFLUX (Maxwell et al. Theor Chem Acc 135:195, 2016) to complexes bound by weak intermolecular interactions. The investigation features the first application of the approach to bound complex systems, additionally challenged by investigating complexes held together only weakly, through either a predominant dispersion contribution, or through mixed dispersion and hydrogen-bonding. Our approach uses the interacting quantum atoms (IQA) energy partitioning scheme to obtain the intra-atomic, $$ {E}_{\mathrm{intra}}^{\mathrm{A}} $$ , and interatomic, $$ {V}_{\mathrm{inter}}^{{\mathrm{AA}}^{\hbox{'}}} $$ , energies, which when summed, compose the molecular energy, $$ {E}_{\mathrm{IQA}}^{\mathrm{system}} $$ . The $$ {E}_{\mathrm{intra}}^{\mathrm{A}} $$ and $$ {V}_{\mathrm{inter}}^{{\mathrm{AA}}^{\hbox{'}}} $$ energies are mapped to the positions of the nuclear coordinates through the machine learning method kriging to build atomic energy models. A model's quality is established through its ability to accurately predict the atomic and molecular energies of atoms in an external test set. Mean absolute error percentages (MAE%) of 1.5, 1.5, 1.6, 1.0, 2.6 and 1.7% are obtained in recovering the molecular energy for ammonia...benzene, water...benzene, HCN...benzene, methane...benzene, stacked-benzene ( C ) dimer and T-benzene ( C ) dimer complexes, respectively. [ABSTRACT FROM AUTHOR]

In this study, a novel high-isolation wideband divider based on multi-layer elliptical defected ground structure coupler is presented along with its analytical theory and design procedure. The proposed divider could be conveniently applied for high- power applications with less loss for the absence of isolation resistors. The simulation results show that in 3.1–10.6 GHz, the return loss S11 and S22 are <−15 dB, the overall isolation S23 is <−20 dB and the best part achieves−50 dB. Insertion loss S21 and S31 are both >−4 dB within 4–9 GHz, and the amplitude and phase difference between port 2 and port 3 is <1 dB and 2°, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the kink effect in scattering parameter S22 of RF power MOSFETs with drain-to-spacer offset is explained quantitatively for the first time. Our results show that for RF power MOSFETs the output impedance can be represented by a “shifted” series RC circuit at low frequencies and a “shifted” parallel RC circuit at high frequencies. The appearance of the kink point of S22 in a Smith chart is caused by this inherent ambivalent characteristic of the output impedance. It is found that an increase of drain-to-spacer offset enhances the kink effect. In addition, the kink effect in S22 of RF power MOSFETs can also be interpreted in terms of poles and zeros. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 371–376, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10767 [ABSTRACT FROM AUTHOR]

• Double-hybrid density functional theory (DH-DFT) is accurate but expensive for larger systems. • Here an efficient dual-basis DH-DFT is derived and implemented for general use in GAMESS. • Differences between dual-basis and conventional DH-DFT energies are negligible. • Benchmark comparisons reveal dual-basis DH-DFT offers comparable accuracy to state-of-the-art neural-network-based approaches at a reduced computational expense. We present a computationally efficient implementation of double-hybrid density functional theory (DH-DFT) leveraging the dual basis methods of Head-Gordon and co-workers and the resolution-of-the-identity second-order Møller-Plesset (RI-MP2) theory. The B2PLYP, B2GP-PLYP, DSD-BLYP and DSD-PBEP86 density functionals are applied to assess the performance of dual-basis methods on several benchmark test cases, including the CONF set of conformational energy differences in C4-C7 alkanes, the S22 set of noncovalent interaction energies, and the RGC10 noble-gas dimer dissociation curves. The dual-basis DH-DFT approach is shown to give results in excellent agreement with conventional methods at a reduced computational cost. For noncovalent interaction energies, DH-DFT is compared against a leading neural-network-based approach, namely the SNS-MP2 method of McGibbon and coworkers (McGibbon et al., 2017). The DH-DFT and SNS-MP2 methods are shown to produce similar accuracies when compared to the established benchmark values. [ABSTRACT FROM AUTHOR]

The progression of cystic fibrosis (CF) from an acute to a chronic disease is often associated with the conversion of the opportunistic pathogen Pseudomonas aeruginosa from a nonmucoid form to a mucoid form in the lung. This conversion involves the constitutive synthesis of the exopolysaccharide alginate, whose production is under the control of the AlgT/U sigma factor. This factor is regulated posttranslationally by an extremely unstable process and has been commonly attributed to mutations in the algT (algU) gene. By exploiting this unstable phenotype, we isolated 34 spontaneous nonmucoid variants arising from the mucoid strain PDO300, a PAO1 derivative containing the mucA22 allele commonly found in mucoid CF isolates. Complementation analysis using a minimal tiling path cosmid library revealed that most of these mutants mapped to two protease-encoding genes, algO, also known as prc or PA3257, and mucP. Interestingly, our algO mutations were complemented by both mucP and algO, leading us to delete, clone, and overexpress mucP, algO, mucE, and mucD in both wild-type PAO1 and PDO300 backgrounds to better understand the regulation of this complex regulatory mechanism. Our findings suggest that the regulatory proteases follow two pathways for regulated intramembrane proteolysis (RIP), where both the AlgO/MucP pathway and MucE/AlgW pathway are required in the wild-type strain but where the AlgO/MucP pathway can bypass the MucE/AlgW pathway in mucoid strains with membrane-associated forms of MucA with shortened C termini, such as the MucA22 variant. This work gives us a better understanding of how alginate production is regulated in the clinically important mucoid variants of Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]