bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal mechanisms underlying recovery from forward masking in multielectrode-implant listeners
Authors: Chatterjee Monita
Published: July 2002

This paper describes a detailed study of recovery from forward masking in six users of the Nucleus-22 cochlear implant with a range of performance in speech-recognition tests. Recovery from a 300-ms-long pulse train presented at 1000 pps was found to be fastest in the poorer performers. The shape of the recovery function was found to be most strongly influenced by masker duration, suggesting that temporal integration plays a prominent role in recovery from forward masking. The recovery functions are reasonably well described by a sum of two exponentially decaying processes. Their relative weights depend on the amount of temporal integration occurring during the masker, and show strong intersubject variability. Nonmonotonicities sometimes observed in the recovery functions may be accounted for by considering the influence of neural adaptation.
Group delays of distortion product otoacoustic emissions in the guinea pig
Authors: Schneider Sandra , Prijs Vera F. , Schoonhoven Ruurd
Published: July 2002

This paper presents a comprehensive set of experimental data on group delays of distortion product otoacoustic emissions (DPOAEs) in the guinea pig. Group delays of the DPOAEs with frequencies 2f1−f2, 3f1−2f2, 4f1−3f2, and 2f2−f1 were measured with the phase gradient method. Both the f1- and the f2-sweep paradigm were used. Differences between the two sweep paradigms were investigated for the four DPOAEs, as well as the group delay differences between the DPOAEs. Analysis revealed larger group delays with the f2-sweep paradigm, but only for the lower sideband DPOAEs (with fdp<f1,f2). For the lower sideband cubic distortion product 2f1−f2, the f2-sweep delays were a factor of 1.17–1.54 larger than the f1-sweep delays, depending on frequency. The upper sideband DPOAE 2f2−f1 showed no significant difference between f1- and f2-sweep group delays, except for the highest and lowest f2 frequencies. Comparing the group delays of the DPOAEs for each sweep paradigm separately, equal group delays were found for all four DPOAEs measured with the f1-sweep. With the f2-sweep paradigm on the other hand, the group delays of the three lower sideband DPOAEs occurred to be larger than the group delays of the upper sideband DPOAE 2f2−f1. A tentative interpretation of the data in the context of proposed explanatory hypotheses on DPOAE group delays is given.
Individual differences in external-ear transfer functions reduced by scaling in frequency
Authors: Middlebrooks John C.
Published: July 2002

This study examined inter-subject differences in the transfer functions from the free field to the human ear canal, which are commonly know as head-related transfer functions. The directional components of such transfer functions are referred here to as directional transfer functions (DTFs). The DTFs of 45 subjects varied systematically among subjects in regard to the frequencies of spectral features such as peaks and notches. Inter-subject spectral differences in DTFs were quantified between 3.7 and 12.9 kHz for sound-source directions throughout the coordinate sphere. For each pair of subjects, an optimal frequency scale factor aligned spectral features between subjects and, thus, minimized inter-subject spectral differences. Frequency scaling of DTFs reduced spectral differences by a median value of 15.5% across all pairs of subjects and by more than half in 9.5% of subject pairs. Optimal scale factors showed a median value of 1.061 and a maximum of 1.38. The optimal scale factor between any pair of subjects correlated highly with the ratios of subjects’ maximum interaural delays, sizes of their external ears, and widths of their heads.
Intensity discrimination and detection of amplitude modulation
Authors: Wojtczak Magdalena , Viemeister Neal F.
Published: July 2002

Thresholds for detection of low-rate sinusoidal amplitude modulation and for detection of intensity increments were measured over a wide range of levels in an examination of the relationship between these fundamental aspects of intensity processing. As expected, thresholds measured with a continuous 1-kHz tone decrease with increasing carrier/pedestal level. For levels between 6 and 85 dB SPL the data are well described by 10 log ΔI/I=0.44⋅(20 log m)+D(fm), where ΔI/I is the Weber fraction for increment detection, m is the modulation index at threshold, and D(fm) depends on modulation rate (fm). The relationship between the psychometric functions for modulation and increment detection is also consistent with this equation. The data indicate a clear relationship between modulation and increment detection and thus provide an important additional consideration for models of modulation processing. No existing models provide an adequate account of this relationship.
The adaptive beam-tracing algorithm
Authors: Drumm I. A. , Lam Y. W.
Published: July 2002

The most popular models to predict sound propagation in architectural spaces involve the tracing of rays, images, or beams. Most current beam-tracing methods use conical or triangular beams that may produce overlaps and holes in the predicted sound field. Hence a new method has been developed whereby the shape of reflected beams is governed by the shape of reflecting surfaces so as to produce a geometrically perfect description of the sound propagation for halls with occluding surfaces. The method also facilitates the calculation of diffuse sound propagation by managing the energy transfer from a specular model to a diffuse model. This adaptive beam-tracing method compares well with other methods in terms of speed and accuracy.
Acoustic normal mode fluctuation statistics in the 1995 SWARM internal wave scattering experiment
Authors: Headrick Robert H. , Lynch James F. , Kemp John N. , Newhall Arthur E. , von der Heydt Keith , Apel John , Badiey Mohsen , Chiu Ching-sang , Finette Steve , Orr Marshall , Pasewark Bruce , Turgot Alton , Wolf Steve , Tielbuerger Dirk
Published: July 2002

In order to understand the fluctuations imposed upon low frequency (50 to 500 Hz) acoustic signals due to coastal internal waves, a large multilaboratory, multidisciplinary experiment was performed in the Mid-Atlantic Bight in the summer of 1995. This experiment featured the most complete set of environmental measurements (especially physical oceanography and geology) made to date in support of a coastal acoustics study. This support enabled the correlation of acoustic fluctuations to clearly observed ocean processes, especially those associated with the internal wave field. More specifically, a 16 element WHOI vertical line array (WVLA) was moored in 70 m of water off the New Jersey coast. Tomography sources of 224 Hz and 400 Hz were moored 32 km directly shoreward of this array, such that an acoustic path was constructed that was anti-parallel to the primary, onshore propagation direction for shelf generated internal wave solitons. These nonlinear internal waves, produced in packets as the tide shifts from ebb to flood, produce strong semidiurnal effects on the acoustic signals at our measurement location. Specifically, the internal waves in the acoustic waveguide cause significant coupling of energy between the propagating acoustic modes, resulting in broadband fluctuations in modal intensity, travel-time, and temporal coherence. The strong correlations between the environmental parameters and the internal wave field include an interesting sensitivity of the spread of an acoustic pulse to solitons near the receiver.
Range estimation and depth discrimination of multiple sources in noisy shallow waters without knowing sound speed profiles
Authors: Lu I-Tai , Wu Hsuan-Ling
Published: July 2002

A bottom-mounted horizontal array is proposed for range estimation and depth discrimination of multiple sources where the SSP information of the environment is not required. The two key elements are, first, to use the horizontal array for deriving modal wave numbers and composite modal amplitudes excited by multiple sources in multiple frequencies and, second, to utilize the frequency samples for obtaining unknown source ranges and discriminating source depths.
Approximate expressions for viscous attenuation in marine sediments: Relating Biot’s “critical” and “peak” frequencies
Authors: Turgut Altan
Published: July 2002

Simple approximate relations are proposed for the viscous attenuation per cycle of the fast compressional and shear waves in the low-to-intermediate frequency range. Corresponding closed-form formulas are derived for frequencies at which maximum viscous attenuation per cycle occurs according to the Biot–Stoll theory of elastic wave propagation in marine sediments. In the new formulas, Biot’s approximation [M. A. Biot, J. Acoust. Soc. Am. 34, 1254–1264 (1962)] for the frequency-dependent viscosity correction factor F(f ) and the assumption of relatively low specific loss (Q−1<0.2) [J. Geertsma and D. C. Smith, Geophysics 26(2), 169–181 (1962)] are used to provide an accurate representation of the fast compressional and shear wave attenuation from low frequencies through a transition region extending to two or three times Biot’s critical frequency fc. The approximate viscodynamic behavior of marine sediments for the fast compressional and shear waves shows similarities to that of a “homogeneous relaxation” process for an anelastic linear element [A. M. Freudenthal and H. Geiringer, Encyclopedia of Physics (Springer-Verlag, 1958), Vol. 6].
A Modified Pochettino Viscometer for the Measurement of the Viscoelastic Properties of High Polymer Melts
Authors: Myers A. W. , Faucher J. A.
Published: July 2002

A modified Pochettino viscometer has been developed for the measurement of fundamental viscoelastic properties of polymer melts. The calculation and evaluation of various viscoelastic constants and functions from experimental stress-strain and stress relaxation curves are discussed. The terminal zone relaxation spectra for three polyethylenes of similar melt index are presented.
The Effect of Small Amounts of Long and Short Branches on the Steady State Flow Behavior of Polyethylene-Wax Blends: Application of Concentration Superposition
Authors: Nakajima Nobuyuki , Stark Casper F. , Hoffman Ray D.
Published: July 2002

Steady-state flow curves were obtained on a series of polyethylene-wax blends over a shear rate range of 10−2 to 10+3 sec−1. Wax concentration extended from 0 to 85%. The wax was a low molecular weight polyethylene (M̄w=5400 and M̄w/M̄n=1.54). Seven polyethylenes with melt indices ranging 0.3 to 9 and M̄w/M̄n ranging from 3 to 15 were examined. Included in the samples were homopolymers, copolymers with a small amount of short branches, copolymers with a small amount of short and long branches, and low density polyethylene. Concentration superpossability was demonstrated with these samples. For the high molecular weight polymers, superposition provided a means of estimating the low shear Newtonian viscosity, η0, which could not be directly measured. Values of η0 were compared to M̄w obtained by GPC. The effects of branches on the concentration shift factors for superposition were discussed.
Comparison of the Dynamic Mechanical Properties of Two Styrene-Butadiene-Styrene Triblock Copolymers with 1,2- and 1,4-Polybutadiene Center Blocks
Authors: Cohen R. E. , Tschoegl N. W.
Published: July 2002

The dynamic mechanical properties of a polystyrene-1,2-polybutadiene-polystyrene (SBS) triblock copolymer were studied in free oscillation experiments near 0.2 Hz from −50 to 100°C and in forced oscillations over a frequency range from 0.1 to 1000 Hz at various temperatures between 1 and 96°C. For data which covered essentially the polybutadiene transition region, the temperature dependence of the mechanical properties could be described by a WLF equation whose parameters are in close agreement with those describing homopolybutadiene of similar microstructure. Data outside the polybutadiene transition region showed considerable lack of superposition when reduced by the WLF equation, as observed earlier in a triblock of similar molecular architecture but having a 1,4-polybutadiene center segment. Contour plots of the loss compliance as a function of the temperature and the logarithmic frequency revealed significant differences in the temperature and frequency dependence of various viscoelastic mechanisms responsible for the thermorheological complexity seen in both materials.
Changes of refractive index ellipsoid by biaxial drawing of a PET film (abstract)
Authors: Sakamoto Kunisuke
Published: July 2002

The change of optical property on transverse drawing of a uniaxially oriented PET film was investigated. The birefringence in the plane of film decreased in proportion to transverse draw ratio, and come to zero in the optically balanced condition. The optical axis of a uniaxially oriented film separated into two optical axes in the plane perpendicular to the transverse draw direction. At the optically balanced condition, the two separated optical axes joined into one optical axis perpendicular to the plane of films. These observations could be described well with a model based on the assumption that a refractive index in each principal direction changes in proportion to draw ratio.
The diffusion tensor for Hookean dumbbells in steady shear flow: Analytical approximation
Authors: Prakash J. Ravi , Mashelkar R. A.
Published: July 2002

Thermodynamic treatments of the phenomenon of polymer migration in inhomogeneous flows have so far assumed a flow rate independent coefficient of diffusion. Recent investigations have revealed that polymer diffusivity in simple shear flow is anisotropic and flow rate dependent. These properties arise because the average spatial extent of the macromolecule, from being spherical at equilibrium, becomes ellipsoidal on the imposition of a shear flow.Using this insight into the molecular shape, and assuming that there is only one physically important direction in the problem due to the flow field, we derive an approximate analytical expression for the diffusion tensor. This gives values within 1.2% of exact numerical ones, for a wide range of dimensionless shear rates. Clearly, it is important to refine the earlier thermodynamic theories of polymer migration by incorporating the shear rate dependence of polymer diffusivity. The expression derived in this paper is anticipated to be useful in a wide range of problems, where the assumption of ‘‘local homogeneity’’ is justified.
Structural recovery of ferrite suspensions (abstract)
Authors: Kanai Hiroyuki , Amari Takeshi
Published: July 2002

In order to investigate the structural recovery of suspension of acicular γ-ferrite powder in mineral oil, viscoelastic properties were measured intermittently with small amplitude oscillatory shearing (strain at 0.3%, rate at 10 rad/s). A Couette test fixture was used for the measurements. Storage and loss moduli of the suspension immediately after cessation of large amplitude oscillatory pre- shearing (strain at 50%–500%, rate at 50 rad/s, for 20 min) increased with increasing strain amplitude of preshearing. The moduli of the suspension at the early stage of recovery were found to follow the scaling equation: G′ (or G ″) ∼ tn, where t is the resting time after cessation of preshearing. The moduli decayed after reaching the maximum, when larger amplitude preshearing had been applied. The phenomenon is interpreted from the view point of percolation using a two-level (intra- and interfloc level) network model of flocculated suspensions.
Studies on elongational viscosity of polymer melts (abstract)
Authors: Koyama Kiyohito
Published: July 2002

This paper summarizes an experimental study on an elongational rheometer and elongational viscosity measurements of polymer melt developed by the present author and his coworkers. The elongational viscosity increases with time by two steps: One is a gradual viscosity increase at small strain and the other is a rapid viscosity increase at large strain. The rapid viscosity increase behavior does not depend on strain rate, temperature, and average molecular weight, but does depend on molecular weight distribution and chain branching. These experimental results were explained by introduction of small amounts of extremely long relaxation time mode into the normal relaxation spectrum which is estimated from linear viscoelastic data. The elongational rheometer can quickly detect the extremely long relaxation time mode.
Birefringence of amorphous polymers III. On the modified stress-optical rule (abstract)
Authors: Okamoto Hirotaka , Hayashihara Hiroshi , Inoue Tadashi , Osaki Kunihiro
Published: July 2002

The stress-optical rule (SOR) does not hold valid in the glassy and the glass-to-rubber transition zones of amorphous polymers. The birefringence and stress can be related through a modified SOR: The stress is composed of two components each of which contributes to the birefringence with different degree of effectiveness. Studies of Read [Polym. Eng. Sci. 23, 835 (1983)] and of the present authors [Macromolecules, 24, 5670 (1991)] are based on different methods of assignment of the stress-optical coefficients for the two components. We show that the two component viscoelastic functions derived from the latter method are thermorheologically simple but those from the former are not.
A recursive model for Rheotens tests
Authors: Rauschenberger V. , Laun H. M.
Published: July 2002

An iterative model is described to predict isothermal and nonisothermal elongation of an extruded filament at a given force. The principle of the model allows a quite simple description of Rheotens tests with much flexibility regarding the shape of the elongational viscosity function, including true viscoelastic flow and thermal boundary conditions. The algorithm is compact and computing time on a PC is short. The application of an integral K-BKZ constitutive equation to predict Rheotens curves of the well characterized LDPE Melt I is demonstrated and the influence of the slope of the transient viscosity in the strain-hardening regime is discussed. A simple approximation to take into account the prehistory of the material in the die based on purely elongational strains is proposed which includes the irreversibility assumption of the damping function (Wagner model). Predicted Rheotens curves are compared with experimental results.
Neuromotor control associates with muscle weakness observed with McArdle sign of multiple sclerosis
Authors: Schilaty Nathan D. , Savoldi Filippo , Nasr Zahra , Weinshenker Brian G.
Published: March 2022

Objective

Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progressive worsening. A specific finding of MS‐associated myelopathy is McArdle sign, wherein neck flexion is associated with prominent increased limb weakness relative to that detected with neck extension. In this study, we characterized neuromotor control properties of finger extensors in association with the McArdle sign.

Methods

A custom‐built device was utilized to monitor torque production of the wrist extensors with simultaneous recording of surface electromyography of the extensor digitorum. The electromyography was decomposed and analyzed via both linear and nominal regressions.

Results

Linear regressions demonstrated a strong difference between groups for MS from healthy controls and other myelopathies for motor unit action potential amplitude and average firing rate (p < 0.001). Further, linear regression demonstrated good correlations of neuromotor variables to mechanical torque output (0.24 ≤ R2 ≤ 0.76). Nominal regression distinguished MS from healthy controls with an AUC of 0.87, specificity of 0.97, and sensitivity of 0.64. Nominal regression of MS from other myelopathies demonstrated an AUC of 0.88, specificity of 0.85, and sensitivity of 0.79.

Interpretation

These data demonstrate the neuromotor control factors that largely determine muscle force production change with the observation of McArdle sign; these neuromotor control factors can differentiate MS from both healthy controls and other myelopathy conditions.
Adaptive event‐triggered fault detection for nonlinear networked systems in finite‐frequency domain under stochastic cyber‐attacks
Authors: Zhu Qi , Jiang Shun , Pan Feng
Published: March 2022

This article investigates the fault detection problem in finite‐frequency domain for a class of nonlinear networked systems under stochastic cyber‐attacks. A novel adaptive event‐triggered scheme is introduced to mitigate the transmission burden of the network. A unified measurement model is proposed to take the randomly occurring cyber‐attacks and the transmission delays into account simultaneously. Under the consideration of fault sensitivity and disturbance robustness, the addressed fault detection problem is converted into an auxiliary filtering problem by properly augmenting the states of the original system and the fault detection filter. Intensive stochastic analysis is carried out to obtain sufficient conditions for the existence of the desired fault detection filter, and the corresponding optimal filter parameters can be easily derived by solving a convex optimization problem. Finally, an illustrative example is presented to show the effectiveness and applicability of the proposed method.
Sulfur Treatment Passivates Bulk Defects in Sb2Se3 Photocathodes for Water Splitting
Authors: Prabhakar Rajiv Ramanujam , Moehl Thomas , Friedrich Dennis , Kunst Marinus , Shukla Sudhanshu , Adeleye Damilola , Damle Vinayaka H. , Siol Sebastian , Cui Wei , Gouda Laxman , Suh Jihye , Tischler Yaakov R. , van de Krol Roel , Tilley S. David
Published: March 2022

Sb2Se3 has emerged as an important photoelectrochemical (PEC) and photovoltaic (PV) material due to its rapid rise in photoconversion efficiencies. However, Sb2Se3 has a complex defect chemistry, which reduces the maximum photovoltage. Thus, it is important to understand these defects and develop defect passivation strategies in Sb2Se3. A comprehensive investigation of the charge carrier dynamics of Sb2Se3 and the influence of sulfur treatment on its optoelectronic properties is performed using time‐resolved microwave conductivity (TRMC), photoluminescence (PL) spectroscopy, and low‐frequency Raman spectroscopy (LFR). The key finding in this work is that upon sulfur treatment of Sb2Se3, the carrier lifetime is increased by the passivation of deep defects in Sb2Se3 in both the surface region and the bulk, which is evidenced by increased charge carrier lifetime of TRMC decay dynamics, increased radiative recombination efficiency, decreased deep defect level emission (PL), and the emergence of new vibration modes by LFR.
Paper‐Structure Inspired Multiresponsive Hydrogels with Solvent‐Induced Reversible Information Recording, Self‐Encryption, and Multidecryption
Authors: Chen Zhen , Chen Yujie , Guo Yutong , Yang Zhi , Li Hua , Liu Hezhou
Published: March 2022

Information recording and encryption/decryption functions are essential due to the prevalence of counterfeiting activities and information leakage in the current age. However, the development of high‐resolution information recording and multistage information protection systems to achieve high data security levels, such as self‐erasing encrypted data and time‐controlled data handling, remains limited. Herein, inspired by the information‐recording structure of paper, a multiresponsive nanofiber‐reinforced poly(N‐isopropylacrylamide) (PNIPAM) hydrogel (NCPN hydrogel) with improved mechanical properties, solvent‐induced high‐resolution reversible information recording, self‐encryption, and multi‐decryption capabilities, is proposed. Due to the unique hydrophilic and hydrophobic structures of the hydrogel matrix, ethanol and other polar analogs can be applied as special inks to record information by changing the lower critical solution temperature to achieve the repeatable transmittance variation. The recorded information can be erased via water wiping or ethanol volatilization. Additionally, self‐encryption can be achieved and adjusted based on the ethanol volatilization time and concentration difference, and confidential information can be further decrypted in a water environment or under a thermal stimulus. Furthermore, several stable, repeatable, and fast‐response hydrogel‐based information‐recognition systems are designed and investigated. Therefore, the designed hydrogel‐based informational platform provides a universal information‐handling system allowing for the reversible recording of information, with self‐encryption and multidecryption capabilities.
An Expanding Foam‐Fabric Orthopedic Cast
Authors: Root Samuel E. , Sanchez Vanessa , Tracz Jovanna A. , Preston Daniel J. , Zvi Yoav S. , Wang Kemble , Walsh Conor J. , Homer‐Vanniasinkam Shervanthi , Whitesides George M.
Published: March 2022

Traditional orthopedic casting strategies used in the treatment of fractured limbs, such as fiberglass and plaster‐based tapes, suffer from several drawbacks, including technically challenging molding for application, occurrence of skin complications, and the requirement of a potentially hazardous oscillatory saw for removal, which is frightening for pediatric patients. This work presents the design and evaluation of a foam‐fabric cast (FFC) to overcome these drawbacks by integrating strategies from soft materials engineering and functional apparel design. A fabric sleeve is designed to enable the reactive injection molding of a polymer foam and provide a form‐fitting orthopedic cast for the human forearm—with sufficient mechanical reinforcement to stabilize a fractured limb. Through testing with a replica limb and human subjects with a range of forearm volumes, the FFC application process is demonstrated and characterized. The thermal, pressural, chemical, and hygienic safety are comparable to or safer than existing clinical technologies. The FFC weighs only ≈150 g, is water resistant, and represents a robust alternative to traditional casts that can be i) manufactured at a large scale for a low cost; ii) applied to patients simply, rapidly (≈5 min), and reliably; and iii) removed easily with a pair of scissors.
Multimaterial Multinozzle Adaptive 3D Printing of Soft Materials
Authors: Uzel Sebastien G. M. , Weeks Robert D. , Eriksson Michael , Kokkinis Dimitri , Lewis Jennifer A.
Published: March 2022

Direct ink writing is a facile method that enables biological, structural, and functional materials to be printed in three dimensions (3D). To date, this extrusion‐based method has primarily been used to soft materials in a layer‐wise manner on planar substrates. However, many emerging applications would benefit from the ability to conformally print materials of varying composition on substrates with arbitrary topography. Here, a high throughput platform based on multimaterial multinozzle adaptive 3D printing (MMA‐3DP) that provides independent control of nozzle height and seamless switching between inks is reported. To demonstrate the MMA‐3DP platform, conformally pattern viscoelastic inks composed of triblock copolymer, gelatin, and photopolymerizable polyacrylate materials onto complex substrates of varying topography, including those with surface defects that mimic skin abrasions or deep gouges. This platform opens new avenues for rapidly patterning soft materials for structural, functional, and biomedical applications.
Measuring binary fluidization of nonspherical and spherical particles using machine learning aided image processing
Authors: Li Cheng , Gao Xi , Rowan Steven L. , Hughes Bryan , Rogers William A.
Published: March 2022

The binary fluidization of Geldart D type nonspherical wood particles and spherical low density polyethylene (LDPE) particles was investigated in a laboratory‐scale bed. The experiment was performed for varying static bed height, wood particles count, as well as superficial gas velocity. The LDPE velocity field were quantified using particle image velocimetry (PIV). The wood particles orientation and velocity are measured using particle tracking velocimetry (PTV). A machine learning pixel‐wise classification model was trained and applied to acquire wood and LDPE particle masks for PIV and PTV processing, respectively. The results show significant differences in the fluidization behavior between LDPE only case and binary fluidization case. The effects of wood particles on the slugging frequency, mean, and variation of bed height, and characteristics of the particle velocities/orientations were quantified and compared. This comprehensive experimental dataset serves as a benchmark for validating numerical models.
Autonomous Nanocrystal Doping by Self‐Driving Fluidic Micro‐Processors
Authors: Bateni Fazel , Epps Robert W. , Antami Kameel , Dargis Rokas , Bennett Jeffery A. , Reyes Kristofer G. , Abolhasani Milad
Published: March 2022

Lead halide perovskite (LHP) nanocrystals (NCs) are considered an emerging class of advanced functional materials with numerous outstanding optoelectronic characteristics. Despite their success in the field, their precision synthesis and fundamental mechanistic studies remain a challenge. The vast colloidal synthesis and processing parameters of LHP NCs in combination with the batch‐to‐batch and lab‐to‐lab variation problems further complicate their progress. In response, a self‐driving fluidic micro‐processor is presented for accelerated navigation through the complex synthesis and processing parameter space of NCs with multistage chemistries. The capability of the developed autonomous experimentation strategy is demonstrated for a time‐, material‐, and labor‐efficient search through the sequential halide exchange and cation doping reactions of LHP NCs. Next, a machine learning model of the modular fluidic micro‐processors is autonomously built for accelerated fundamental studies of the in‐flow metal cation doping of LHP NCs. The surrogate model of the sequential halide exchange and cation doping reactions of LHP NCs is then utilized for five closed‐loop synthesis campaigns with different target NC doping levels. The precise and intelligent NC synthesis and processing strategy, presented herein, can be further applied toward the autonomous discovery and development of novel impurity‐doped NCs with applications in next‐generation energy technologies.
Characterizing Lipid‐Coated Mesoporous Silica Nanoparticles as CD169‐Binding Delivery System for Rilpivirine and Cabotegravir
Authors: Zang Han , Fofana Josiane , Xu Fangda , Nodder Sarah B. , Gummuluru Suryaram , Reinhard Björn M.
Published: March 2022

Herein, lipid‐coated mesoporous silica nanoparticles (LMSNs) are investigated as biomimetic delivery vehicle for two antiretroviral (ARV) compounds, rilpivirine (RPV), and cabotegravir (CAB). Monosialodihexosylganglioside (GM3) is incorporated into the membrane to facilitate LMSN binding to CD169 (Siglec‐1)‐expressing myeloid cells, that are predominantly expressed in secondary lymphoid tissues in vivo. It is demonstrated that in addition to providing CD169‐binding functionalities, the lipid membrane around the silica core provides stealth properties that dampen the inflammatory cytokine response to ARVs‐loaded LMSN in human monocyte‐derived macrophages. Quantification of RPV and CAB releases from nanoparticles, and assessment of antiviral potency to human immunodeficiency virus 1 (HIV‐1) infection in vitro reveals that RPV and CAB co‐formulated into LMSN retain optimal antiviral potency for 90 days, even upon storage at room temperature, making LMSN an attractive nanoplatform, immune to cold chain requirements. These findings suggest that GM3–LMSN equip the mesoporous silica nanoparticle (MSN) core with lipid‐derived properties for surface passivation and lipid‐mediated binding that are of high interest for achieving an effective delivery of ARVs to tissue reservoirs of HIV‐1 replication.
A Dinuclear Metallobridged Super Aryl‐Extended Calix[4]pyrrole Cavitand
Authors: Sun Qingqing , Escobar Luis , Ballester Pablo
Published: March 2022

A super aryl‐extended calix[4]pyrrole equipped with four oxazolo[4,5‐b]pyrazinyl units at its upper rim is reported. Its PtII/PdII‐metallobridged cavitand counterparts were obtained by treatment with 2 equiv of cis‐protected metal corners, [M(dppp)(OTf)2] (dppp=1,3‐(bis‐diphenylphosphino)propane). The metal corners arranged their axial phenyl substituents near the aromatic walls of the cavitand leading to the formation of inclusion complexes as single conformers. We characterized the inclusion complexes in solution using NMR spectroscopy. Selected complexes were also characterized in the gas‐phase and in the solid‐state using mass spectrometry and X‐ray diffraction analysis. The dimensions of the open portals of the dinuclear complexes were found to be dependent on the included guest. The results of DFT calculations served to explain the dissimilar complexation‐induced shifts observed in the dinuclear inclusion complexes with mono‐ and bis‐formamide guests.
Photoredox Activation of Inert Alkyl Chlorides for the Reductive Cross‐Coupling with Aromatic Alkenes
Authors: Aragón Jordi , Sun Suyun , Pascual David , Jaworski Sebastian , Lloret‐Fillol Julio
Published: March 2022

The inertness of chloroalkanes has precluded them as coupling partners for cross‐coupling reactions. Herein we disclose a general strategy for the activation of inert alkyl chlorides through photoredox catalysis and their use as coupling partners with alkenes. The catalytic system is formed by [Ni(OTf)(Py2Tstacn)](OTf) (1Ni), which is responsible for the Csp3−Cl bond activation, and [Ir(NMe2bpy)(ppy)2]PF6,(PCIrNMe2), which is the photoredox catalyst. Combined experimental and theoretical studies show an in situ photogenerated NiIintermediate ([Ni(Py2Tstacn)]+) which is catalytically competent for the Csp3−Cl bond cleavage via a SN2 mechanism for primary alkyl chlorides, forming carbon‐centered free radicals, which react with the olefin leading to the formation of the Csp3−Csp3bond. These results suggest inert alkyl chlorides can be electrophiles for developing new intermolecular strategies in which low‐valent aminopyridine nickel complexes act as key catalytic species.
Endo‐M Mediated Chemoenzymatic Approach Enables Reversible Glycopeptide Labeling for O‐GlcNAcylation Analysis
Authors: Chen Yao , Tang Feng , Qin Hongqiang , Yue Xuyang , Nie Yongzhan , Huang Wei , Ye Mingliang
Published: March 2022

To selectively enrich O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) peptides in their original form from complex samples, we report the first reversible chemoenzymatic labeling approach for proteomic analysis. In this strategy, the O‐GlcNAc moieties are ligated with long N‐glycans using an Endo‐M mutant, which enables the enrichment of the labeled glycopeptides by hydrophilic interaction liquid chromatography (HILIC). The attached glycans on the enriched glycopeptides are removed by wild‐type Endo‐M/S to restore the O‐GlcNAc moiety. Compared with classic chemoenzymatic labeling, this approach enables the tag‐free identification, and eliminates the interference of bulky tags in glycopeptide detection. This approach presents a unique avenue for the proteome‐wide analysis of protein O‐GlcNAcylation to promote its mechanism research.
Benzo‐Extended Cyclohepta[def]fluorene Derivatives with Very Low‐Lying Triplet States
Authors: Wu Fupeng , Ma Ji , Lombardi Federico , Fu Yubin , Liu Fupin , Huang Zhijie , Liu Renxiang , Komber Hartmut , Alexandropoulos Dimitris I. , Dmitrieva Evgenia , Lohr Thorsten G. , Israel Noel , Popov Alexey A. , Liu Junzhi , Bogani Lapo , Feng Xinliang
Published: March 2022

Open‐shell non‐alternant polycyclic hydrocarbons (PHs) are attracting increasing attention due to their promising applications in organic spintronics and quantum computing. Herein we report the synthesis of three cyclohepta[def]fluorene‐based diradicaloids (1–3), by fusion of benzo rings on its periphery for the thermodynamic stabilization, as evidenced by multiple characterization techniques. Remarkably, all of them display a very narrow optical energy gap (Egopt=0.52–0.69 eV) and persistent stability under ambient conditions (t1/2=11.7–33.3 h). More importantly, this new type of diradicaloids possess a low‐lying triplet state with an extremely small singlet–triplet energy gap, as low as 0.002 kcal mol−1, with a clear dependence on the molecular size. This family of compounds thus offers a new route to create non‐alternant open‐shell PHs with high‐spin ground states, and opens up novel possibilities and insights into understanding the structure–property relationships.
Numerical simulation and instability analysis of particles in liquid–solid concave‐wall jet using DPM‐RSM
Authors: Zhang Jing , Li Xiang , Gong Bin , Li Yaxia , Wang Wei , Wang Shengchang , Wu Jianhua
Published: March 2022

The liquid–solid concave‐wall jet existed in the vertical cylinder separator with tangential inlet; the instability near concave‐wall was the key factor for centrifugal separation. The effects of jet flowrate and wall curvature radius on the instability of solid‐particles were explored by experiment and numerical simulation. The results showed that the separation efficiency of particles decreased with the increase of centrifugal separation factor. The liquid–solid concave‐wall jet flow in separator was unstable in this study. The decay rate of jet maximum velocity on the concave‐wall was larger than that on plane‐wall jet. The ratio of half‐width value to wall curvature radius was about 0.08 at the circumferential direction 90°, which coincided with the critical value of centrifugal instability in strongly concave‐wall jet. The pressure, velocity, and vorticity fluctuated periodically along streamwise direction in separator. The fluctuation period was linearly related to the wall curvature, and the radial range of fluctuation was only half of jet width. The paired longitudinal vortices formed along the flow direction, and the longitudinal vortices merged at length 0.74 m from the inlet cross‐section along circumferential direction. After the position of vortices merged, the particle trajectory oscillated obviously.
SNP‐based heritability and selection analyses: Improved models and new results
Authors: Speed Doug , Kaphle Anubhav , Balding David J.
Published: March 2022

Complex‐trait genetics has advanced dramatically through methods to estimate the heritability tagged by SNPs, both genome‐wide and in genomic regions of interest such as those defined by functional annotations. The models underlying many of these analyses are inadequate, and consequently many SNP‐heritability results published to date are inaccurate. Here, we review the modelling issues, both for analyses based on individual genotype data and association test statistics, highlighting the role of a low‐dimensional model for the heritability of each SNP. We use state‐of‐art models to present updated results about how heritability is distributed with respect to functional annotations in the human genome, and how it varies with allele frequency, which can reflect purifying selection. Our results give finer detail to the picture that has emerged in recent years of complex trait heritability widely dispersed across the genome. Confounding due to population structure remains a problem that summary statistic analyses cannot reliably overcome. Also see the video abstract here: https://youtu.be/WC2u03V65MQ
Investigation on the interaction between myricetin and dihydromyricetin with trypsin, α‐chymotrypsin, lysozyme by spectroscopy and molecular docking methods
Authors: Meng Xianxin , Nan Guanjun , Shi Bowen , Li Wanlu , Liu Henglin , Lin Rong , Yang Guangde , Zheng Shaohua
Published: March 2022

The interaction between myricetin and dihydromyricetin with trypsin, α‐chymotrypsin and lysozyme was investigated using multispectral and molecular docking methods. The results of fluorescence quenching revealed that myricetin and dihydromyricetin could quench the intrinsic fluorescence of three different proteinases through a static quenching procedure. The binding constant and number of binding sites at different temperatures were measured. The thermodynamic parameters obtained at different temperatures showed van der Waals interactions and hydrogen bonds played the main roles in the interaction of myricetin with trypsin and lysozyme, hydrophobic force was dominant both in myricetin with α‐chymotrypsin interaction and dihydromyricetin with trypsin and lysozyme interaction, as for the electrostatic forces, it was mainly the driving force in dihydromyricetin binding to α‐chymotrypsin. There was non‐radiative energy transfer between three proteinases and myricetin or dihydromyricetin with high probability. The microenvironment of trypsin, α‐chymotrypsin and lysozyme is changed. The docking studies revealed that myricetin and dihydromyricetin entered the hydrophobic cavity of three proteinases and formed hydrogen bonds. The binding affinity of myricetin or dihydromyricetin is different with the trypsin, α‐chymotrypsin and lysozyme due to the different molecular structure.
Estimation of grain quality parameters in rice for high‐throughput screening with near‐infrared spectroscopy and deep learning
Authors: Ravichandran Prabahar , Viswanathan Sadhasivam , Ravichandran Sridhar , Pan Ya‐Jun , Chang Young K.
Published: March 2022

Background and Objectives

Grain quality is a complex trait in rice, compared with other staple crops as it is predominantly consumed as a whole grain. Although considered secondary to yield, to align with consumer preferences, breeders are increasingly interested in quality. At the early stages of a breeding program, grain quality‐related traits are often ignored as they are arduous and time‐consuming. Near‐infrared spectroscopy (NIRS) could be a suitable high‐throughput alternative to conventional wet chemistry and image processing‐related methods to be adopted for early screening. This study aims to quantify traits essential for rice breeders such as amylose, chalkiness, length, width, and the length/width ratio in rice samples with NIRS. We used conventional algorithms such as principal component analysis (PCA), partial least square regression (PLSR), multilayer perceptron (MLP), support vector classification (SVC), and linear discriminant analysis (LDA) to compare with the proposed convolutional neural network (CNN) for regression and classification.

Findings

Our results showed that the proposed CNN outperformed the conventional models in estimating all traits. Unlike conventional models, CNN models could be developed with raw spectra with minimal to no preprocessing, and along with the transfer‐learning capabilities, the time required for model development could be significantly reduced.

Conclusion

We recommend NIRS for quantitative estimation of amylose and chalkiness in rice and rather use classification/categorized estimation for other physical dimension‐related traits such as length and length/width ratio.

Significance and Novelty

We found NIRS to be an appropriate alternative to wet chemistry and image‐based methods for screening lines at the early stages of the breeding program. Estimation of physical parameters such as length and length/width ratio with NIRS is novel and appears reasonable for high‐throughput applications.
Long‐term demographic dynamics of a keystone scavenger disrupted by human‐induced shifts in food availability
Authors: Almaraz Pablo , Martínez Félix , Morales‐Reyes Zebensui , Sánchez‐Zapata José A. , Blanco Guillermo
Published: March 2022

Scavenging is a key ecological process controlling energy flow in ecosystems and providing valuable ecosystem services worldwide. As long‐lived species, the demographic dynamics of vultures can be disrupted by spatiotemporal fluctuations in food availability, with dramatic impacts on their population viability and the ecosystem services provided. In Europe, the outbreak of bovine spongiform encephalopathy (BSE) in 2001 prompted a restrictive sanitary regulation banning the presence of livestock carcasses in the wild on a continental scale. In long‐lived vertebrate species, the buffering hypothesis predicts that the demographic traits with the largest contribution to population growth rate should be less temporally variable. The BSE outbreak provides a unique opportunity to test for the impact of demographic buffering in a keystone scavenger suffering abrupt but transient food shortages. We studied the 42‐year dynamics (1979–2020) of one of the world's largest breeding colonies of Eurasian griffon vultures (Gyps fulvus). We fitted an inverse Bayesian state‐space model with density‐dependent demographic rates to the time series of stage‐structured abundances to investigate shifts in vital rates and population dynamics before, during, and after the implementation of a restrictive sanitary regulation. Prior to the BSE outbreak the dynamics was mainly driven by adult survival: 83% of temporal variance in abundance was explained by variability in this rate. Moreover, during this period the regulation of population size operated through density‐dependent fecundity and subadult survival. However, after the onset of the European ban, a 1‐month delay in average laying date, a drop in fecundity, and a reduction in the number of fledglings induced a transient increase in the impact of fledgling and subadult recruitment on dynamics. Although adult survival rate remained constantly high, as predicted by the buffering hypothesis, its relative impact on the temporal variance in abundance dropped to 71% during the sanitary regulation and to 54% after the ban was lifted. A significant increase in the relative impact of environmental stochasticity on dynamics was modeled after the BSE outbreak. These results provide empirical evidence on how abrupt environmental deterioration may induce dramatic demographic and dynamic changes in the populations of keystone scavengers, with far‐reaching impacts on ecosystem functioning worldwide.
BOVIDS: A deep learning‐based software package for pose estimation to evaluate nightly behavior and its application to common elands (Tragelaphus oryx) in zoos
Authors: Gübert Jennifer , Hahn‐Klimroth Max , Dierkes Paul W.
Published: March 2022

Only a few studies on the nocturnal behavior of African ungulates exist so far, with mostly small sample sizes. For a comprehensive understanding of nocturnal behavior, the data basis needs to be expanded. Results obtained by observing zoo animals can provide clues for the study of wild animals and furthermore contribute to a better understanding of animal welfare and better husbandry conditions in zoos. The current contribution reduces the lack of data in two ways. First, we present a stand‐alone open‐source software package based on deep learning techniques, named Behavioral Observations by Videos and Images using Deep‐Learning Software (BOVIDS). It can be used to identify ungulates in their enclosure and to determine the three behavioral poses “Standing,” “Lying—head up,” and “Lying—head down” on 11,411 h of video material with an accuracy of 99.4%. Second, BOVIDS is used to conduct a case study on 25 common elands (Tragelaphus oryx) out of 5 EAZA zoos with a total of 822 nights, yielding the first detailed description of the nightly behavior of common elands. Our results indicate that age and sex are influencing factors on the nocturnal activity budget, the length of behavioral phases as well as the number of phases per behavioral state during the night while the keeping zoo has no significant influence. It is found that males spend more time in REM sleep posture than females while young animals spend more time in this position than adult ones. Finally, the results suggest a rhythm between the Standing and Lying phases among common elands that opens future research directions.