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Native chemical ligation (NCL) and its modified versions (ligation-desulfurization chemistry) have revolutionized the way that large peptides and proteins are obtained by chemical synthesis. Ligation-desulfurization chemistry can generate thiol-derived peptide models, which can generate proteins through reductive desulfurization. The C-S bond cleavages are involved in the process. It is important for us to comprehend the strength of the C-S bond estimated by the homolytic bond dissociation enthalpies (BDEs). Therefore, 25 DFT methods were chosen to calculate the C-S BDEs of the 55 organic sulfides. It is reliable to predict C-S BDEs by M05-2X method with the corresponding root mean square error value of 6.2 kJ/mol. Then, the C-S BDEs of the thiol-derived peptide model and the structure-activity relationships were systematically researched by using this method. Besides, so as to comprehend the nature of the C-S BDE change mode, the analysis comprised of the natural bond orbit and the energies of frontier orbitals were studied.

The importance of selenium compounds in chemistry and biochemistry has become apparent. The pKa values are important for understanding the reactivity and applicability of selenium compounds. To this end, we calculated the the pKa values of 16 selenols in aqueous solution by using two kinds of DFT methods and PCM-Bondi, SMD and SMDsSAS models. It is observed that the highest precision with a lowest RMSE value of 0.38 pK units was provided by using the ωB97XD method with the SMD model. Therefore, this theoretical protocol was employed to calculate the pKa values of selenol compounds and selenoxo forms of selenocarboxylic acid compounds including R = alkyl, cycloalkyl, benzyl, allyl and aryl as well as the substituent effects. The results suggest that selenols can give higher pKa values than selenocarboxylic acids. Generally, for both substituted selenols and selenocarboxylic acids, EWGs can decrease the pKa values and EDGs can increase the pKa values, and the pKa of the EWG of –COOH is larger and the pKa values of the EDGs of –NH2 and –N(CH3)2 are smaller. In addition, linear relationships between the pKa values with the natural charges of Se atoms, EHOMO, etc. were obtained in different types of selenols and selenocarboxylic acids.

In this letter, we propose ultra-compact TE-polarized even-to-odd mode converter designs by introducing Ge/Si patterns into silicon waveguide-integrated functional region. The Ge areas with continuous boundaries are determined by topology optimization that combines finite element method, geometric projection method, and method of moving asymptotes. Both two-dimensional (2D) and quasi-3D designs are presented. Simultaneous beam splitting and phase shifting are achieved in the functional region with only $1.0 \times 1.55\;{\rm{\mu }}{{\rm{m}}^2}$ area. Based on the 3D finite-difference time-domain simulations, the quasi-3D designs possess satisfactory mode purity (>0.99) at center wavelength 1550 nm, and the mode purity keeps higher than 0.92 within the wavelength range from 1500 to 1600 nm. Meanwhile, the forward transmission efficiency is shown higher than 0.89 within the operational bandwidth. Moreover, the robustness is demonstrated by considering the loss of Ge material and the geometric deviations. The proposed mode-order converters bring together advantages including wavelength footprint, high mode purity, low insertion loss, and large operational bandwidth.

Among other aims, degrowth calls for a deprioritization of economic growth as primary indicator of success. However, deprioritizing economic growth is challenging because it is the antithesis of business as we know it today. Yet, in this study, we find examples of enterprises operating in the renewable energy industry in the Global South, which deprioritize traditional economic growth as their preferred indicator of success. We interviewed 30 renewable energy enterprises (REEs) on the basis of an importance-performance analysis (IPA). Our findings confirm that conventional measures of financial performance are not universally applicable to all enterprises in the Global South. Specifically, we observed that the REEs that are least satisfied with conventional economic performance indicators possess two characteristics in common: (1) they have strong social motivations (e.g., energy access and poverty alleviation) and (2) they are averse to economic growth in the traditional sense. We draw insights from these REEs for the future of post-growth enterprise, including the importance of localness in success and performance appraisal as the Global South transitions toward degrowth. We also introduce 14 alternative performance indicators, suggested by the REEs themselves, which may help bring enterprises closer to post-growth orientation in the Global South.

In this work, we introduce Ni nanopyramid arrays (NPAs) supported amorphous Ge anode architecture and demonstrate its effective improvement in sodium storage properties. The Ni−Ge NPAs are prepared by facile electrodeposition and sputtering method, which eliminates the need for any binder or conductive additive when used as a Na‐ion battery anode. The electrodes display stable cycling performance and enhanced rate capabilities in contrast with planar Ge electrodes, which can be owing to the rational design of the architectured electrodes and firm bonding between current collector and active material (i. e. Ni and Ge, respectively). To validate improvement of nanostructures on electrochemical performance, sodium insertion behavior of crystalline Ge derived from Mg2Ge precursor has been investigated, in which limited but effective enhancement of sodium storage properties are realized by introducing porous nanostructure in crystalline Ge. These results show that elaborately designed configuration of Ge electrodes may be a promising anode for Na‐ion battery applications.

Thiol compounds have been shown to be important in many fields such as protein chemistry and carbohydrate chemistry. Their pKa's in aqueous solution are important for understanding the properties and reactivities of thiols in complex biochemical systems. To elucidate the structure–activity relationships and substituent effects on pKa's of thiols, pKa's of 58 thiols were calculated using different DFT methods with two types of solvation models including PCM-Bondi and SMDsSAS. It was found that the M06-2X method with the SMDsSAS model can give the optimal precision with the smallest RMSE value of 0.77 pK unit. Based on this model, the pKa's of thiols (R-SH in which R = alkyl, cycloalkyl, aryl, heterocyclyl and fluorinated hydrocarbyl) were systematically investigated. The substituent effects as well as the structure–activity relationships behind these data were also examined. Significant substituent effects were found in heterocyclyl, alkynyl and fluorinated hydrocarbyl thiols with a wide pKa range of over 10.0 pK units. In addition, analyses including the natural bond orbital (NBO) and the energies of frontier orbitals were performed in order to further understand the substituent effects on pKa's. Good linear relationships between the pKa's with substituent constants σp+ and natural charges on S atoms were observed in different types of thiols.

Rhodium transition-metal-organic cooperative catalysis, which has been intensively studied by many chemists, represents a great success in C–H bond activation because of high efficiencies and selectivities. Typically, in the reaction mechanism of aldehyde and alkene catalyzed by Rh(I) complex and 2-amino-3-picoline, two kinds of metala-cyclic transition-metal complexes of (iminoacyl)rhodium(III)hydride and (iminoacyl)rhodium(III) alkyl are generally formed. The two complexes play an important role in the overall reaction, in which the Rh–C bond formations are involved. So it is meaningful to understand the strength of Rh–C bond, which can be measured by the homolytic bond dissociation enthalpies (BDEs). To this end, we first calculated 16 relative Rh–C BDEs of Tp′Rh(CNneopentyl)RH (Tp′ = hydridotris-(3,5-dimethylpyrazolyl)borate) by 19 density functional theory (DFT) methods. Furthermore, the 5 absolute Rh–C BDEs of Rh transition-metal complexes were also calculated. The results show that the B97D3 is the most accurate method to predict the relative and absolute Rh–C BDEs and the corresponding RMSE values are the smallest of 2.8 and 3.3 kcal/mol respectively. Therefore, the Rh–C BDEs of (iminoacyl)rhodium(III)hydride and (iminoacyl)rhodium(III)alkyl as well as the substituent effects were investigated by using the B97D3 method. The results indicated that the different substituents exhibit different effects on different types of Rh–C BDEs. In addition, the analysis including the natural bond orbital (NBO) as well as the energies of frontier orbitals were performed in order to further understand the essence of the Rh–C BDE change patterns.

In the dual catalytic Suzuki–Miyaura reactions, the cross-coupling of Csp3-hybridized center organotrifluoroborate salts has been implemented successfully by single-electron transfer (SET), where the redox potentials are important for understanding the reactivities of organotrifluoroborate salts. To this end, the ΔGgas values of 27 organotrifluoroborate anions were calculated by using different composite high-level ab initio and DFT methods. Among different DFT methods, the M05-2X method gave the highest precision with a smallest RMSE of 1.58 kcal mol−1. Then, the 24 E° values of organotrifluoroborate anions were calculated by using the M05-2X method with two types of solvation models including PCM and SMD. It was found that the M05-2X method with a PCM–UAHF model can provide the most accurate results with the lowest RMSE value of 0.16 V. Therefore, the E° values of Csp3-hybridized center organotrifluoroborate anions (R–CH2–BF3−) including R = alkenyl, alkynyl, aryl and heterocyclyl and the Csp2-hybridized center vinyltrifluoroborate anions were systematically investigated with this theoretical protocol. The results indicated that for the Csp3-hybridized center organotrifluoroborate anions, the E° values range from 0.36 V to 1.57 V, and the electron-donating groups (EDG) of –N(CH3)2, –NHCH3etc. can significantly lower the E° values of organotrifluoroborate anions, which are favorable for reactions, whereas the electron-withdrawing groups (EWG) of –NO2, –CN etc. make the organotrifluoroborate anions unfavorable for reactions. For the Csp2-hybridized center organotrifluoroborate anions, the E° values range from 1.38 V to 2.43 V. In addition, the analysis of the natural bond orbital (NBO), the ground-state effect (GE), the radical-state effect (RE) and the energies of frontier orbitals was performed in order to further disclose the essence of the E° value change patterns. The linear relationships between the E° values with substituent constants σ+p and the natural charges of the corresponding C atoms of radicals, etc. were found in different types of organotrifluoroborate anions.

We propose and numerically demonstrate a design of bidirectional transverse electric (TE) polarized mode-order converter based on silicon-on-insulator platform. This converter is realized by introducing high refractive index material inlaid in a silicon slab waveguide. Simulated by three-dimensional finite-difference method time-domain, the forward (TE0 to TE1-like conversion) transmittance reaches approximately 88.2%, while the backward value (TE1 to TE0-like conversion) is about 89.4% at the wavelength of 1550 nm. The footprint of this converter is as small as 0.95 × 1.5 μm2. Fabrication tolerance analysis demonstrates satisfactory robustness. Moreover, we present a polarization-independent converter with slightly modified geometry. The transmittance keeps above 87.2% within the wavelength range from 1500 nm to 1600 nm for both TE and transverse magnetic modes. These devices are expected to contribute to the on-chip mode division multiplexing.

We propose a design of reciprocal optical diode based on asymmetric spatial mode conversion in multimode silicon waveguide on the silicon-on-insulator platform. The design possesses large bandwidth, high contrast ratio and high fabrication tolerance. The forward even-to-odd mode conversion and backward blockade of even mode are achieved by partial depth etching in the functional region. Simulated by three-dimension finite-difference time-domain method, the forward transmission efficiency is about −2.05 dB while the backward transmission efficiency is only −22.68 dB, reaching a highest contrast ratio of 0.983 at the wavelength of 1550 nm. The operational bandwidth is up to 200 nm (from 1450 nm to 1650 nm) with contrast ratio higher than 0.911. The numerical analysis also demonstrates that the proposed optical diode possesses high tolerance for geometry parameter errors which may be introduced in fabrication. The design based on partial depth etching is compatible with CMOS process and is expected to contribute to the silicon-based all-optical circuits.

Based on the germanium-on-insulator (GeOI) platform, we numerically demonstrate a photonic polarization rotator (PR) operating in the 2 μ m waveband. Utilizing the partial-height etching to break the symmetry of germanium waveguide cross section, the proposed PR realizes a 90° polarization rotation between the fundamental transverse electric (TE) and magnetic (TM) modes. The device footprint occupies only 0.4 μ m × 0 . 4 μ m × 3 μ m. This PR shows a low insertion loss of 0.096 dB, a remarkably high polarization conversion efficiency (PCE) of 98.9%, and an extremely high extinction ratio of 33.45 dB at the wavelength of 2005 nm The PCE keeps above 95.4% within the waveband between 1.9 μ m and 2.1 μ m. Furthermore, a reasonable robustness is demonstrated.

We propose a silicon-based asymmetric directional coupler assisted by subwavelength grating anisotropic metamaterial operating at the emerging 2 μm waveband. The effective medium theory is utilized to explain the principle of the proposed structure. Three devices with mode-order conversions are presented. Firstly, TE0-to-TE1, TE0-to-TE2, and TE0-to-TE3 conversions with remarkably high transmittance (>−0.17 dB) and extremely high mode purity (>98.81%) are achieved at the central wavelength of 1985 nm. The fabrication tolerance analyses demonstrate reasonable robustness of the proposed structure. Secondly, such structure can realize a reciprocal optical diode with an exceedingly high contrast ratio (>34 dB) based on spatial symmetry breaking. Finally, we present a symmetric 3 dB mode converter and splitter just by adjusting the length of subwavelength grating and the gap of asymmetric directional coupler. The results reveal that the transmittances of both output ports approach −3 dB around 2 μm and the transmittance difference remains below −10 dB above 40 nm within the waveband from 1.95 μm to 2.05 μm.

Metasurfaces, two-dimensional structures composed of nanoantennas in an array configuration, can be used to fully control electromagnetic waves, which requires a 2π phase shift. Herein, we apply the silicon metasurface as an example to interpret the mechanisms of full 2π phase coverage. It is found that the mechanism varies from Fabry-Perot resonance to Mie resonance as the period increases for a metasurface with certain height. Particularly, there is a transition region between these two types of resonance. We present the corresponding periods and wavelength regions of the different mechanisms when considering the phase-gradient metasurface with at most three diffraction orders. Moreover, the transmission enhancement of metasurface is investigated. The transmission efficiency can be effectively improved when the nanoantenna is changed from a uniform structure to a gradient-index one. We expect that the results can simplify the design process and provide a reference for the future design of all-dielectric metasurface with 2π phase control.

Online_Appendix for Performance Beyond Economic Growth: Alternatives from Growth-Averse Enterprises in the Global South by Cle-Anne Gabriel, Samira Nazar, Danfeng Zhu and Jodyanne Kirkwood in Alternatives: Global, Local, Political

Wide-field tissue imaging is usually not capable of resolving tissue microstructure. We present High Spatial Frequency Domain Imaging (HSFDI) - a noncontact imaging modality that spatially maps the tissue microscopic scattering structures over a large field of view. Based on an analytical reflectance model of sub-diffusive light from forward-peaked highly scattering media, HSFDI quantifies the spatially-resolved parameters of the light scattering phase function from the reflectance of structured light modulated at high spatial frequencies. We have demonstrated with ex vivo cancerous tissue to validate the robustness of HSFDI in significant contrast and differentiation of the microstructutral parameters between different types and disease states of tissue.

We present a spatial frequency domain imaging (SFDI) study of local hemodynamics in the forearm of healthy volunteers performing paced breathing. Real time Single Snapshot Multiple Frequency Demodulation - Spatial Frequency Domain Imaging (SSMD-SFDI) was used to map the optical properties of the subsurface of the forearm continuously. The oscillations of the concentrations of deoxy- and oxyhemoglobin at the subsurface of the forearm induced by paced breathing are found to be close to out-of-phase, attributed to the dominance of the blood flow modulation by paced breathing. The properties of local microcirculation including the blood transit times through capillaries and venules are extracted by fitting to Simplified Hemodynamics Model. Our preliminary results suggest that the real time SSMD-SFDI platform may serve as one effective imaging modality for microcirculation monitoring.

In parallel with the R&D efforts in USA and Europe, China’s National High-tech R&D program has setup its goal in developing petaflops computers. Researchers and engineers world-wide are looking for appropriate methods and technologies to achieve the petaflops computer system. Based on discussion on important design issues in developing the petaflops computer, this paper raises the major technological challenges including the memory wall, low power system design, interconnects, and programming support, etc. Current efforts in addressing some of these challenges and in pursuing possible solutions for developing the petaflops systems are presented. Several existing systems are briefly introduced as examples, including Roadrunner, Cray XT5 jaguar, Dawning 5000A/6000, and Lenovo DeepComp 7000. Architectures proposed by Chinese researchers for implementing the petaflops computer are also introduced. Advantages of the architecture as well as the difficulties in its implementation are discussed. Finally, future research direction in development of high productivity computing systems is discussed.

Pseudomonas sp. CTN-4 degrades chlorothalonil (CTN) but not acetamiprid (AAP), and Pigmentiphaga sp. strain AAP-1 degrades AAP but not CTN. A functional strain, AC, was constructed through protoplast fusion of two parental strains (Pseudomonas sp. CTN-4 and Pigmentiphaga sp. strain AAP-1) in order to simultaneously improve the degradation efficiency of AAP and CTN. Fusant-AC with eight transfers on plates containing two antibiotics and CTN was obtained. For the purpose of identifying and confirming the genetic relationship between fusant-AC and its parents, randomly amplified polymorphic DNA (RAPD), scanning electron microscopy (SEM), and 16S ribosomal DNA (rDNA) analysis were performed. In toto, RAPD fingerprint analysis produced 194 clear bands with 9 primers, which not only had bands in common with strains CTN-4 and AAP-1, but also had its own novel fusant-specific bands. The genetic similarity indices between fusant-AC and parental strains CTN-4 and AAP-1 were 0.40 and 0.69, respectively. The result of SEM indicated that the cell morphology of fusant-AC differed from both its parents. The fusant strain AC possesses a strong capability for AAP and CTN degradation. At AAP concentration (50-300 mg L(-1)), the degradation was achieved within 5 h. At the initial dose of 50 and 100 mg L(-1) CTN, the percentages reached 96 and 91 % over a 36-h incubation period. The present study indicates that the protoplast-fusion technique may have possible applications in environmental pollution control.

Hardware prefetching is widely employed in modern processors. It has been proved that prefetching can significantly improve application’s performance unless it exhibits sparse locality. Nevertheless, prefetching may result in performance degradation in CMP systems as it issues many off-chip memory requests. In this paper, we propose MCPref, a prefetching mechanism that is sensitive to the load of memory bus. Unlike traditional prefetching mechanism, MCPref opens when memory bus is starve and halts when memory bus is busy. Simulation results show that our non-feedback prefetcher design is effective in the scenario of multi-core architecture.

Caching is an important technique to improve computer system performance by storing the most recently used data and instructions for main memory. Cache is widely used in modern computer systems and will continue to be an irreplaceable unit to narrow the speed gap between processor and main memory. With the increasing capacity of main memory and the number of processor cores, the cache technology has great development. In this paper, we have some lessons of cache hierarchy changes with the memory technology from experimental methodology. We design a serial of experiments and try to answer some questions about cache designs. Our experiments results indicate that more levels of cache does not necessarily means better performance for all benchmarks, that last level cache miss rate has no direct connection with the system performance, that the average performance of exclusive cache hierarchy is more effective than that of inclusive cache.

In the present study, we have formulated a phase description of a neuronal oscillator with non-instantaneous synaptic inputs, by using the phase sensitivity function. By numerical simulation, we found that the synaptic time constant is an important factor for global network synchronization. If the synaptic time constant is smaller, perfectly synchronized behavior quickly occurs. As the synaptic time constant is increased, periodic synchronization emerges. However, synchronized activity is lost for larger synaptic time constant. The external periodic stimulation can change the synchronized patterns in the neuronal population. With a stronger stimulation or high-frequency stimulation, synchronized bursting occurred in the neuronal population.