A spectral power analysis of driving behavior changes during the transition from nondistraction to distraction

<p><b>Objective</b>: This article investigated and compared frequency domain and time domain characteristics of drivers' behaviors before and after the start of distracted driving.</p> <p><b>Method</b>: Data from an existing naturalistic driving study were used. Fast Fourier transform (FFT) was applied for the frequency domain analysis to explore drivers' behavior pattern changes between nondistracted (prestarting of visual–manual task) and distracted (poststarting of visual–manual task) driving periods. Average relative spectral power in a low frequency range (0–0.5 Hz) and the standard deviation in a 10-s time window of vehicle control variables (i.e., lane offset, yaw rate, and acceleration) were calculated and further compared. Sensitivity analyses were also applied to examine the reliability of the time and frequency domain analyses.</p> <p><b>Results</b>: Results of the mixed model analyses from the time and frequency domain analyses all showed significant degradation in lateral control performance after engaging in visual–manual tasks while driving. Results of the sensitivity analyses suggested that the frequency domain analysis was less sensitive to the frequency bandwidth, whereas the time domain analysis was more sensitive to the time intervals selected for variation calculations. Different time interval selections can result in significantly different standard deviation values, whereas average spectral power analysis on yaw rate in both low and high frequency bandwidths showed consistent results, that higher variation values were observed during distracted driving when compared to nondistracted driving.</p> <p><b>Conclusions</b>: This study suggests that driver state detection needs to consider the behavior changes during the prestarting periods, instead of only focusing on periods with physical presence of distraction, such as cell phone use. Lateral control measures can be a better indicator of distraction detection than longitudinal controls. In addition, frequency domain analyses proved to be a more robust and consistent method in assessing driving performance compared to time domain analyses.</p

In silico study of androgen receptor N-terminal domain and exploration of its modulators

The androgen receptor (AR, Uniprot: P10275) signaling plays a key role in the progression of prostate cancer, various AR-related ligands have been reported to treat prostate cancer. However, some resistance mechanisms limited the treating effect of these ligands. Since DBD binding or the allosteric binding sites in LBD of AR may allow the circumvention of some drug resistance mechanisms, anti-resistance is expected especially through the NTD (N-terminal domain) targeting. What’s more, studies have shown that compounds including EPI-001 and its derivatives which bind to the Tau-5 region on NTD could be promising molecules for AR-based therapeutics. Herein, we employed aMD (accelerated molecular dynamics) simulation to fold Tau-5 unit proteins into native structure correctly. Subsequently, based on the predicted structural features of Tau-5, the virtual screening was conducted to discover new compounds targeting AR-NTD. We picked up 8 compounds (according to their docking scores and partly similar structural consists as known AR ligands) and analyzed their interaction with Tau-5, compared with the positive control EPI-001, four of the pick-up compounds showed better glide scores. Interestingly, although compound 8 had a lower docking score, it consisted of a similar component as the ligand EIQPN and the amide derivatives, this predicts that compound 8 has also the potential to be modified into an excellent AR-NTD binding molecule. These 8 compounds were all commercially available and could be tested to check whether there was a hit compound to bind the AR-NTD and to regulate its bio-activities. Together, this study described an in silico VLS approach to discover AR-NTD ligands and provided more choices for developing AR-targeted therapies. Communicated by Ramaswamy H. Sarma</p

Synthesis and Structure of Self-Assembled Pd₂Au₂₃(PPh₃)₁₀Br₇ Nanocluster: Exploiting Factors That Promote Assembly of Icosahedral Nano-Building-Blocks

The essential force of self-assembly in the nanocluster range is not intrinsically understood to date. In this work, the synergistic effect between metals was exploited to render the self-assembly from the icosahedral M₁₃ (M = Pd, Au) nano-building-blocks. Single-crystal X-ray diffraction analysis revealed that the two Pd₁Au₁₂ icosahedrons were linked by five halogen linkages, and the assembled structure was determined to be Pd₂Au₂₃­(PPh₃)₁₀Br₇. The finding of Au–halogen linkages in the rod-like M₂₅ nanoclusters has not been previously reported. Furthermore, the calculations on Hirshfeld charge analysis were performed, which implied that the reduced electronic repulsion (induced by the synergistic effect of Pd and Au metals) between two icosahedral units promoted the assembly. This study sheds light on the deep understanding of the essential force of self-assembly from icosahedral nano-building-blocks

Two Electron Reduction: From Quantum Dots to Metal Nanoclusters

The quantum dots (QDs) and metal nanoclusters (MNCs) have recently attracted increasing interest due to their intriguing physical–chemical properties. Nevertheless, the inherent correlations between them have rarely been explored. In this study, we successfully achieved the conversion of the silver QDs ([Ag₆₂S₁₃(SBu^t)₃₂]⁴⁺) to silver MNCs ([Ag₆₂S₁₂(SBu^t)₃₂]²⁺) via the electrochemical reduction method. A key intermediate could be obtained by setting the voltage at (−0.6) V, and its atomic structure has been determined to be [Ag₆₂S₁₃(SBu^t)₃₂]²⁺ by single crystal X-ray crystallography. After that, the centroid S atom in the Ag₁₄S cubic core can be extruded out of the clusters through the window via an energy favorable route during the reducing process which will be reported for the first time. The detailed conversion process and the accompanying changes of optical properties were studied. Our work revealed a unique case that QDs could be converted to MNCs

Two Electron Reduction: From Quantum Dots to Metal Nanoclusters

The quantum dots (QDs) and metal nanoclusters (MNCs) have recently attracted increasing interest due to their intriguing physical–chemical properties. Nevertheless, the inherent correlations between them have rarely been explored. In this study, we successfully achieved the conversion of the silver QDs ([Ag₆₂S₁₃(SBu^t)₃₂]⁴⁺) to silver MNCs ([Ag₆₂S₁₂(SBu^t)₃₂]²⁺) via the electrochemical reduction method. A key intermediate could be obtained by setting the voltage at (−0.6) V, and its atomic structure has been determined to be [Ag₆₂S₁₃(SBu^t)₃₂]²⁺ by single crystal X-ray crystallography. After that, the centroid S atom in the Ag₁₄S cubic core can be extruded out of the clusters through the window via an energy favorable route during the reducing process which will be reported for the first time. The detailed conversion process and the accompanying changes of optical properties were studied. Our work revealed a unique case that QDs could be converted to MNCs

Ag₅₀(Dppm)₆(SR)₃₀ and Its Homologue Au_<i>x</i>Ag_{50–<i>x</i>}(Dppm)₆(SR)₃₀ Alloy Nanocluster: Seeded Growth, Structure Determination, and Differences in Properties

A large thiolate/phosphine coprotected Ag₅₀(Dppm)₆(SR)₃₀ nanocluster was synthesized through the further growth of Ag₄₄(SR)₃₀ nanocluster and characterized by X-ray photoelectron spectroscopy (XPS), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray analysis. This new nanocluster comprised a 32-metal-atom dodecahedral kernel and two symmetrical Ag₉(SR)₁₅P₆ ring motifs. The 20 valence electrons correspond to shell closure in the Jellium model. Moreover, this nanocluster could be alloyed by templated/galvanic metal exchange to the homologue Au_<i>x</i>Ag_{50–<i>x</i>}(Dppm)₆(SR)₃₀ nanocluster; the latter showed much higher thermal stability than the Ag₅₀(Dppm)₆(SR)₃₀ nanocluster. Further experiments were conducted to study the optical, electrical, and photoluminescence properties of both nanoclusters. Our work not only reports two new larger size nanoclusters but also reveals a new way to synthesize larger size silver and alloy nanoclusters, that is, controlled growth/alloying

Ag₅₀(Dppm)₆(SR)₃₀ and Its Homologue Au_<i>x</i>Ag_{50–<i>x</i>}(Dppm)₆(SR)₃₀ Alloy Nanocluster: Seeded Growth, Structure Determination, and Differences in Properties

A large thiolate/phosphine coprotected Ag₅₀(Dppm)₆(SR)₃₀ nanocluster was synthesized through the further growth of Ag₄₄(SR)₃₀ nanocluster and characterized by X-ray photoelectron spectroscopy (XPS), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray analysis. This new nanocluster comprised a 32-metal-atom dodecahedral kernel and two symmetrical Ag₉(SR)₁₅P₆ ring motifs. The 20 valence electrons correspond to shell closure in the Jellium model. Moreover, this nanocluster could be alloyed by templated/galvanic metal exchange to the homologue Au_<i>x</i>Ag_{50–<i>x</i>}(Dppm)₆(SR)₃₀ nanocluster; the latter showed much higher thermal stability than the Ag₅₀(Dppm)₆(SR)₃₀ nanocluster. Further experiments were conducted to study the optical, electrical, and photoluminescence properties of both nanoclusters. Our work not only reports two new larger size nanoclusters but also reveals a new way to synthesize larger size silver and alloy nanoclusters, that is, controlled growth/alloying

Isomerism in Au–Ag Alloy Nanoclusters: Structure Determination and Enantioseparation of [Au₉Ag₁₂(SR)₄(dppm)₆X₆]³⁺

Revealing structural isomerism in a nanocluster remains significant but challenging. Herein, we have obtained a pair of structural isomers, [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-C and [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-Ac [dppm = bis­(diphenyphosphino)­methane; HSR = 1-adamantanethiol/<i>tert</i>-butylmercaptan; X = Br/Cl; C stands for one of the structural isomers being chiral; Ac stands for another being achiral], that show different structures as well as different chiralities. These structures are determined by single-crystal X-ray diffraction and further confirmed by high-resolution electrospray ionization mass spectrometry. On the basis of the isomeric structures, the most important finding is the different arrangements of the Au₅Ag₈@Au₄ metal core, leading to changes in the overall shape of the cluster, which is responsible for structural isomerism. Meanwhile, the two enantiomers of [Au₉­Ag₁₂­(SR)₄­(dppm)₆­X₆]³⁺-C are separated by high-performance liquid chromatography. Our work will contribute to a deeper understanding of the structural isomerism in noble-metal nanoclusters and enrich the chiral nanocluster