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result(s) for
"Alper, John P."
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Effect of Size and Shape on Electrochemical Performance of Nano-Silicon-Based Lithium Battery
by
Herlin-Boime, Nathalie
,
Martin, Eléa
,
Chenevier, Pascale
in
Anodes
,
Aqueous solutions
,
Carbon black
2021
Silicon is a promising material for high-energy anode materials for the next generation of lithium-ion batteries. The gain in specific capacity depends highly on the quality of the Si dispersion and on the size and shape of the nano-silicon. The aim of this study is to investigate the impact of the size/shape of Si on the electrochemical performance of conventional Li-ion batteries. The scalable synthesis processes of both nanoparticles and nanowires in the 10–100 nm size range are discussed. In cycling lithium batteries, the initial specific capacity is significantly higher for nanoparticles than for nanowires. We demonstrate a linear correlation of the first Coulombic efficiency with the specific area of the Si materials. In long-term cycling tests, the electrochemical performance of the nanoparticles fades faster due to an increased internal resistance, whereas the smallest nanowires show an impressive cycling stability. Finally, the reversibility of the electrochemical processes is found to be highly dependent on the size/shape of the Si particles and its impact on lithiation depth, formation of crystalline Li15Si4 in cycling, and Li transport pathways.
Journal Article
Electrochemical and X-ray Photoelectron Spectroscopic Study of Early SEI Formation and Evolution on Si and Si@C Nanoparticle-Based Electrodes
by
Herlin-Boime, Nathalie
,
Franger, Sylvain
,
Alper, John P.
in
Carbon
,
Chemical composition
,
Chemical properties
2022
Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using silicon nanoparticles as the active material. In this work, the comparison of the behavior and chemical composition of the Solid Electrolyte Interphase (SEI) was carried out between Si nanoparticles and carbon-coated Si nanoparticles (Si@C). A combination of two complementary analytical techniques, Electrochemical Impedance Spectroscopy and X-ray Photoelectron Spectroscopy (XPS), was used to determine the intrinsic characteristics of the SEI. It was demonstrated that the SEI on Si particles is more resistive than the SEI on the Si@C particles. XPS demonstrated that the interface on the Si particles contains more oxygen when not covered with carbon, which shows that a protective layer of carbon helps to reduce the number of inorganic components, leading to more resistive SEI. The combination of those two analytical techniques is implemented to highlight the features and evolution of interfaces in different battery technologies.
Journal Article
Toward the Improvement of Silicon-Based Composite Electrodes via an In-Situ Si@C-Graphene Composite Synthesis for Li-Ion Battery Applications
2023
Using Si as anode materials for Li-ion batteries remain challenging due to its morphological evolution and SEI modification upon cycling. The present work aims at developing a composite consisting of carbon-coated Si nanoparticles (Si@C NPs) intimately embedded in a three-dimensional (3D) graphene hydrogel (GHG) architecture to stabilize Si inside LiB electrodes. Instead of simply mixing both components, the novelty of the synthesis procedure lies in the in situ hydrothermal process, which was shown to successfully yield graphene oxide reduction, 3D graphene assembly production, and homogeneous distribution of Si@C NPs in the GHG matrix. Electrochemical characterizations in half-cells, on electrodes not containing additional conductive additive, revealed the importance of the protective C shell to achieve high specific capacity (up to 2200 mAh.g−1), along with good stability (200 cycles with an average Ceff > 99%). These performances are far superior to that of electrodes made with non-C-coated Si NPs or prepared by mixing both components. These observations highlight the synergetic effects of C shell on Si NPs, and of the single-step in situ preparation that enables the yield of a Si@C-GHG hybrid composite with physicochemical, structural, and morphological properties promoting sample conductivity and Li-ion diffusion pathways.
Journal Article
Electrochemical and X-ray photoelectron spectroscopic sudy of early SEI formation and evolution on Si and Si@C nanoparticle-based electrodes
by
Herlin-Boime, Nathalie
,
Franger, Sylvain
,
de Vito, Eric
in
Chemical Sciences
,
Material chemistry
2022
Carbon coatings can help to stabilize the electrochemical performance of high-energy anodes using silicon nanoparticles as the active material. In this work, the comparison of the behavior and chemical composition of the Solid Electrolyte Interphase (SEI) was carried out between Si nanoparticles and carbon-coated Si nanoparticles (Si@C). A combination of two complementary analytical techniques, Electrochemical Impedance Spectroscopy and X-ray Photoelectron Spectroscopy (XPS), was used to determine the intrinsic characteristics of the SEI. It was demonstrated that the SEI on Si particles is more resistive than the SEI on the Si@C particles. XPS demonstrated that the interface on the Si particles contains more oxygen when not covered with carbon, which shows that a protective layer of carbon helps to reduce the number of inorganic components, leading to more resistive SEI. The combination of those two analytical techniques is implemented to highlight the features and evolution of interfaces in different battery technologies.
Journal Article
Long-term neurocognitive outcomes in 204 single-suture craniosynostosis patients
by
Hauc, Sacha C.
,
Alper, David P.
,
Almeida, Mariana N.
in
Medicine
,
Medicine & Public Health
,
Neurosciences
2023
Purpose
Craniosynostosis, which describes premature fusion of one or more cranial sutures, has been associated with a variety of neurocognitive deficits. We sought to explore the cognitive profiles of the various types of single-suture, non-syndromic craniosynostosis (NSC).
Methods
A retrospective review of children 6-18 years old with surgically corrected NSC who underwent neurocognitive testing (Weschler Abbreviated Scale of Intelligence, Beery-Buktenica Developmental Test of Visuomotor Integration) from the years 2014-2022 was conducted.
Results
204 patients completed neurocognitive testing (139 sagittal, 39 metopic, 22 unicoronal, 4 lambdoid suture). 110 (54%) of the cohort was male, and 150 (74%) were White. Mean IQ was 106.10±14.01 and mean age at surgery and testing were 9.0±12.2 months and 10.9±4.0 years, respectively. Sagittal synostosis was associated with higher scores than metopic synostosis, with significant differences in verbal IQ (109.42±15.76 vs 101.37±10.41), full-scale IQ (108.32±14.44 vs 100.05±11.76), visuomotor integration (101.62±13.64 vs 92.44±12.07), visual perception (103.81±12.42 vs 95.87±11.23), and motor coordination (90.45±15.60 vs 84.21±15.44). Sagittal synostosis was associated with significantly higher scores for visuomotor integration (101.62±13.64 vs 94.95±10.24) and visual perception (103.81±12.42 vs 94.82±12.75) than unicoronal synostosis.
Conclusions
Compared to patients with sagittal synostosis, patients with metopic synostosis exhibited lower scores in verbal IQ, full-scale IQ, visuomotor integration, visual perception, and motor control after surgical correction. Despite surgical correction for premature metopic suture fusion, the effect on the adjacent frontal lobe and white matter connections to other regions of the brain may have a lasting functional impact. Patients with unicoronal synostosis exhibited lower visuomotor integration and visual perception scores.
Journal Article
Comparison of emotional and behavioral regulation between metopic and sagittal synostosis
by
Alper, David P.
,
Almeida, Mariana N.
,
Alperovich, Michael
in
Child
,
Child Behavior - physiology
,
Child Behavior - psychology
2024
Purpose
Children with surgically corrected nonsyndromic craniosynostosis have been previously found to have neurocognitive and behavioral difficulties. Children with metopic synostosis have been described to have more difficulties than children with sagittal synostosis. This study aims to characterize the behavioral differences between children with metopic and sagittal synostosis.
Methods
Children with metopic and sagittal synostosis were recruited at school age. Parents completed four separated behavioral assessments: Conners-3 (evaluation of ADHD), Social Responsiveness Scale-2 (SRS-2: evaluation of autism), Behavior Rating Inventory of Executive Function-2 (BRIEF-2: evaluation of executive function), and Child Behavior Checklist (CBCL: evaluation of overall behavioral problems). Children underwent intelligence quotient (IQ) testing using the Wechsler Abbreviated Scale of Intelligence (WASI-II).
Results
There were 91 children (45 with metopic and 46 with sagittal synostosis). More children with metopic synostosis reported requiring supportive services (57.7% vs 34.7%,
p
= 0.02) and more reached or exceeded borderline clinical levels of two executive function subscales of the BRIEF-2 (emotion regulation index: 33.3% vs 17.4%,
p
= 0.05; global executive composite: 33.3% vs 17.4%,
p
= 0.05). Children with sagittal synostosis had higher scores on the rule-breaking and externalizing problem subscales of the CBCL. Increasing age at surgery was associated with worse executive function scores.
Conclusions
A relationship between suture subtype and behavioral outcomes exists at school age. More children with metopic synostosis required social services indicating more overall difficulties. Children with metopic synostosis have more specific problems with executive function, while children with sagittal synostosis had more difficulties with externalizing behaviors.
Journal Article
Radiographic severity is associated with worse executive function in metopic craniosynostosis
by
Hauc, Sacha C.
,
Alper, David P.
,
Almeida, Mariana N.
in
Adolescent
,
Child
,
Craniosynostoses - complications
2024
Background
Children with metopic synostosis have been found to have more neurocognitive and behavioral difficulties. The variables that may affect future neurodevelopmental outcomes, including presenting morphologic severity, have not been fully studied. In the largest study to date, we aimed to assess what portends worse neurocognitive and behavioral outcomes at school age.
Methods
Children 6–18 years old with surgically corrected metopic nonsyndromic craniosynostosis underwent neurocognitive testing. Parents completed behavior rating surveys about their child: Conners-3 (ADHD), Social Responsiveness Scale-2 (autism spectrum disorder), Behavior Rating Inventory of Executive Function-2 (BRIEF-2: executive function), and Child’s Behavior Checklist (overall behavior). The endocranial bifrontal angle (EBA), adjusted EBA (aEBA), frontal angle (FA), and AI-derived metopic severity score (MSS) were determined on pre-operative CT images. Multivariate linear regressions were used to evaluate the association of age at surgery and severity.
Results
There were 87 children who underwent neurocognitive testing (average age 10.9 ± 3.3 years) of whom 67 also completed behavioral assessments. Greater phenotypical severity of metopic synostosis (lower FA, aEBA, and EBA) was associated with worse scores on the subscales of the BRIEF-2 (executive function) and executive subscale of the Conners-3. Increasing age at surgery was associated with worse executive function subscale scores of the Conners-3 when controlling for each severity measurement and sociodemographic risk.
Conclusion
Children with greater phenotypic severity of metopic synostosis have worse executive function at school age. The majority of children with metopic synostosis have signs of ADHD. Later surgeries (greater than 12 months) may impact executive functioning, regardless of the degree of severity. Future research should aim at identifying the direct structural changes to the brain.
Journal Article
Ear Molding Therapy of Congenital Ear Anomalies: Long-Term Aesthetic Outcomes and Caretaker Satisfaction
by
Collar, John L.
,
Alper, David P.
,
Almeida, Mariana N.
in
Caregivers - psychology
,
Cartilage
,
Children & youth
2024
Introduction
Ear molding is a safe, non-surgical approach to treat newborns with congenital ear anomalies. In this study, we aimed to investigate long-term aesthetic outcomes and caretaker satisfaction from ear molding therapy.
Methods
A retrospective chart review from 2018 to 2020 was conducted for infants who underwent ear molding treatment at our institution. Patient demographics and treatment related variables were collected. Caretakers were surveyed regarding their experience, expectations, and aesthetic outcome at 1 year (short-term) and 3 years (long-term) from treatment. Independent physicians evaluated treatment efficacy. Responses were converted to a Likert scale (1–5), with 5 representing most desirable.
Results
Overall, 38 of 42 patients participated in our long-term study (90%) for a total of 62 ears. Average follow-up was 3.31 ± 0.50 years after completion of treatment. Mean age at treatment was 23.2 ± 19.7 days with a mean treatment duration of 21.7 ± 7.7 days. Caretakers’ satisfaction regarding auricular appearance remained high (short-term: 4.18 vs. long-term: 4.17, p = 0.54) and anticipated social distress decreased over time. Physician aesthetic evaluations were favorable between “somewhat effective” and “very effective” and remained consistent over time (short term: 3.46 vs. long-term: 3.31, p = 0.31). Furthermore, physician evaluations were higher for deformations than malformations (p = 0.04) and in children who began treatment by 30 days old (p = 0.04).
Conclusion
Caretaker satisfaction from ear molding therapy remained high after long-term follow up, and social distress from the perception of their child’s ears decreased with time. Physician aesthetic ratings confirmed efficacy, with better outcomes seen in deformations than in malformations.
Level of Evidence IV
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors
www.springer.com/00266
.
Journal Article
Multiomic analyses implicate a neurodevelopmental program in the pathogenesis of cerebral arachnoid cysts
by
Ocken, Jack
,
Alper, Seth L.
,
Carter, Bob S.
in
631/208/212/2301
,
631/378/2571
,
692/420/2489/144
2023
Cerebral arachnoid cysts (ACs) are one of the most common and poorly understood types of developmental brain lesion. To begin to elucidate AC pathogenesis, we performed an integrated analysis of 617 patient–parent (trio) exomes, 152,898 human brain and mouse meningeal single-cell RNA sequencing transcriptomes and natural language processing data of patient medical records. We found that damaging de novo variants (DNVs) were highly enriched in patients with ACs compared with healthy individuals (
P
= 1.57 × 10
−33
). Seven genes harbored an exome-wide significant DNV burden. AC-associated genes were enriched for chromatin modifiers and converged in midgestational transcription networks essential for neural and meningeal development. Unsupervised clustering of patient phenotypes identified four AC subtypes and clinical severity correlated with the presence of a damaging DNV. These data provide insights into the coordinated regulation of brain and meningeal development and implicate epigenomic dysregulation due to DNVs in AC pathogenesis. Our results provide a preliminary indication that, in the appropriate clinical context, ACs may be considered radiographic harbingers of neurodevelopmental pathology warranting genetic testing and neurobehavioral follow-up. These data highlight the utility of a systems-level, multiomics approach to elucidate sporadic structural brain disease.
In a cohort of patients with cerebral arachnoid cysts, multiomic analyses reveal de novo variants causing genetic neurodevelopmental conditions in up to 16% of cases, suggesting that surgery in these cases may not improve non-mass effect-related symptoms.
Journal Article
Genome sequencing and analysis of the model grass Brachypodium distachyon
by
Unité de recherche en génomique végétale (URGV) ; Institut National de la Recherche Agronomique (INRA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS)
,
Chalhoub, Boulos, B
,
Charles, Mathieu
in
631/208/212/748
,
631/208/514/1948
,
Agronomy. Soil science and plant productions
2010
Three subfamilies of grasses, the Ehrhartoideae, Panicoideae and Pooideae, provide the bulk of human nutrition and are poised to become major sources of renewable energy. Here we describe the genome sequence of the wild grass Brachypodium distachyon (Brachypodium), which is, to our knowledge, the first member of the Pooideae subfamily to be sequenced. Comparison of the Brachypodium, rice and sorghum genomes shows a precise history of genome evolution across a broad diversity of the grasses, and establishes a template for analysis of the large genomes of economically important pooid grasses such as wheat. The high-quality genome sequence, coupled with ease of cultivation and transformation, small size and rapid life cycle, will help Brachypodium reach its potential as an important model system for developing new energy and food crops.
Journal Article