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1.
Phys Chem Chem Phys ; 26(17): 13049-13060, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38598198

RESUMO

Iron is an abundant and non-toxic element that holds great potential as energy carrier for large-scale and long-term energy storage. While from a general viewpoint iron oxidation is well-known, the detailed kinetics of oxidation for micrometer sized particles are missing, but required to enable large-scale utilization for energy production. In this work, iron particles are subjected to temperature-programmed oxidation. By dilution with boron nitride a sintering of the particles is prevented enabling to follow single particle effects. The mass fractions of iron and its oxides are determined for different oxidation times using Mössbauer spectroscopy. On the basis of the extracted phase compositions obtained at different times and temperatures (600-700 °C), it can be concluded that also for particles the oxidation follows a parabolic rate law. The parabolic rate constants are determined in this transition region. Knowledge of the particle size distribution and its consideration in modeling the oxidation kinetics of iron powder has proven to be crucial.

2.
Angew Chem Int Ed Engl ; 60(11): 5898-5906, 2021 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-33497000

RESUMO

A new strategy affords "non-nano" carbon materials as dehydrogenation catalysts that perform similarly to nanocarbons. Polymer-based carbon precursors that combine a soft-template approach with ion adsorption and catalytic graphitization are key to this synthesis strategy, thus offering control over macroscopic shape, texture, and crystallinity and resulting in a hybrid amorphous/graphitic carbon after pyrolysis. From this intermediate the active carbon catalyst is prepared by removing the amorphous parts of the hybrid carbon materials via selective oxidation. The oxidative dehydrogenation of ethanol was chosen as test reaction, which shows that fine-tuning the synthesis of the new carbon catalysts allows to obtain a catalytic material with an attractive high selectivity (82 %) similar to a carbon nanotube reference, while achieving 10 times higher space-time yields at 330 °C. This new class of carbon materials is accessible via a technically scalable, reproducible synthetic pathway and exhibits spherical particles with diameters around 100 µm, allowing unproblematic handling similar to classic non-nano catalysts.

3.
Angew Chem Int Ed Engl ; 59(41): 18095-18102, 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-32697377

RESUMO

The key to fully leveraging the potential of the electrochemical CO2 reduction reaction (CO2RR) to achieve a sustainable solar-power-based economy is the development of high-performance electrocatalysts. The development process relies heavily on trial and error methods due to poor mechanistic understanding of the reaction. Demonstrated here is that ionic liquids (ILs) can be employed as a chemical trapping agent to probe CO2RR mechanistic pathways. This method is implemented by introducing a small amount of an IL ([BMIm][NTf2 ]) to a copper foam catalyst, on which a wide range of CO2RR products, including formate, CO, alcohols, and hydrocarbons, can be produced. The IL can selectively suppress the formation of ethylene, ethanol and n-propanol while having little impact on others. Thus, reaction networks leading to various products can be disentangled. The results shed new light on the mechanistic understanding of the CO2RR, and provide guidelines for modulating the CO2RR properties. Chemical trapping using an IL adds to the toolbox to deduce the mechanistic understanding of electrocatalysis and could be applied to other reactions as well.

4.
Genet Med ; 21(8): 1895, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30237574

RESUMO

This Article was originally published under Nature Research's License to Publish, but has now been made available under a [CC BY 4.0] license. The PDF and HTML versions of the Article have been modified accordingly.

5.
Genet Med ; 21(3): 676-682, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30032161

RESUMO

PURPOSE: CADASIL is a small-vessel disease caused by a cysteine-altering pathogenic variant in one of the 34 epidermal growth factor-like repeat (EGFr) domains of the NOTCH3 protein. We recently found that pathogenic variant in EGFr domains 7-34 have an unexpectedly high frequency in the general population (1:300). We hypothesized that EGFr 7-34 pathogenic variant more frequently cause a much milder phenotype, thereby explaining an important part of CADASIL disease variability. METHODS: Age at first stroke, survival and white matter hyperintensity volume were compared between 664 CADASIL patients with either a NOTCH3 EGFr 1-6 pathogenic variant or an EGFr 7-34 pathogenic variant. The frequencies of NOTCH3 EGFr 1-6 and EGFr 7-34 pathogenic variant were compared between individuals in the genome  Aggregation Database and CADASIL patients. RESULTS: CADASIL patients with an EGFr 1-6 pathogenic variant have a 12-year earlier onset of stroke than those with an EGFr 7-34 pathogenic variant, lower survival, and higher white matter hyperintensity volumes. Among diagnosed CADASIL patients, 70% have an EGFr 1-6 pathogenic variant, whereas EGFr 7-34 pathogenic variant strongly predominate in the population. CONCLUSION: NOTCH3 pathogenic variant position is the most important determinant of CADASIL disease severity, with EGFr 7-34 pathogenic variant predisposing to a later onset of stroke and longer survival.


Assuntos
CADASIL/genética , Receptor Notch3/genética , Adulto , Idoso , Encéfalo/patologia , CADASIL/fisiopatologia , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Fenótipo , Domínios Proteicos/genética , Receptor Notch3/fisiologia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/genética
6.
Cancer Immunol Immunother ; 67(6): 935-947, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29556699

RESUMO

The first therapeutic proteasome inhibitor bortezomib has clinical efficacy in mantle cell lymphoma (MCL) which resulted in its incorporation in treatment algorithms for this disease. Impairment of proteasomal function by bortezomib is mediated via inhibition of the 20S core particle. However, proteasome function can also be modified by targeting upstream components of the ubiquitin-proteasome system. Recently, b-AP15 has been identified as a small molecule achieving proteasome inhibition by targeting the deubiquitinase (DUB) activity of the 19S regulatory subunit and was found to inhibit cancer cell growth in preclinical analyses. In the present study, both direct antitumor effects and the possibility to induce natural killer group 2 member D ligands (NKG2DL) to reinforce NK cell immunity with b-AP15 were investigated to provide a rational basis for clinical evaluation of this novel DUB inhibitor in MCL. Treatment with b-AP15 resulted in reduced viability as well as induction of apoptosis in a time- and dose-dependent manner, which could be attributed to caspase activation in MCL cells. In addition, treatment with b-AP15 differentially induced NKG2DL expression and subsequent NK cell lysis of MCL cells. These results indicate that the DUB inhibitor b-AP15 displays substantial antitumor activity in human MCL and suggest that b-AP15 might be a novel therapeutic option in the treatment of MCL that warrants clinical investigation.


Assuntos
Linfoma de Célula do Manto/genética , Piperidonas/uso terapêutico , Proteínas Secretadas Inibidoras de Proteinases/uso terapêutico , Apoptose , Linhagem Celular Tumoral , Humanos , Células Matadoras Naturais/metabolismo , Linfoma de Célula do Manto/metabolismo , Linfoma de Célula do Manto/patologia , Piperidonas/farmacologia , Proteínas Secretadas Inibidoras de Proteinases/farmacologia
7.
Analyst ; 142(6): 925-929, 2017 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-28112294

RESUMO

A hollow-core photonic crystal fibre (HC-PCF), guided by photonic bandgap effects or anti-resonant reflection, offers strong light confinement and long photochemical interaction lengths in a microscale channel filled with a solvent of refractive index lower than that of glass (usually fused silica). These unique advantages have motivated its recent use as a highly efficient and versatile microreactor for liquid-phase photochemistry and catalysis. In this work, we use a single-ring HC-PCF made from a high-index soft glass, thus enabling photochemical experiments in higher index solvents. The optimized light-matter interaction in the fibre is used to strongly enhance the reaction rate in a proof-of-principle photolysis reaction in toluene.

8.
Arch Orthop Trauma Surg ; 136(6): 747-50, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27010468

RESUMO

Medial penetration of the helical blade into the hip joint after fixation of trochanteric fractures using the proximal femur nail antirotation (PFN-A) is a potential failure mode. In low demand patients a blade exchange with cement augmentation may be an option if conversion to total hip arthroplasty is unfeasible to salvage the cut-through. This article describes a technique to avoid intraarticular cement leakage using a cement plug to close the defect in the femoral head caused by the cut-through.


Assuntos
Cimentos Ósseos/efeitos adversos , Pinos Ortopédicos , Extravasamento de Materiais Terapêuticos e Diagnósticos/prevenção & controle , Fraturas do Quadril/cirurgia , Articulação do Quadril/cirurgia , Idoso , Idoso de 80 Anos ou mais , Cadáver , Feminino , Cabeça do Fêmur/cirurgia , Humanos , Masculino , Desenho de Prótese
9.
Angew Chem Int Ed Engl ; 55(6): 2257-61, 2016 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-26668073

RESUMO

Developing cost-effective electrocatalysts for the oxygen reduction reaction (ORR) is a prerequisite for broad market penetration of low-temperature fuel cells. A major barrier stems from the poisoning of surface sites by nonreactive oxygenated species and the sluggish ORR kinetics on the Pt catalysts. Herein we report a facile approach to accelerating ORR kinetics by using a hydrophobic ionic liquid (IL), which protects Pt sites from surface oxidation, making the IL-modified Pt intrinsically more active than its unmodified counterpart. The mass activity of the catalyst is increased by three times to 1.01 A mg(-1) Pt @0.9 V, representing a new record for pure Pt catalysts. The enhanced performance of the IL-modified catalyst can be stabilized after 30 000 cycles. We anticipate these results will form the basis for an unprecedented perspective in the development of high-performing electrocatalysts for fuel-cell applications.

10.
Environ Sci Technol ; 49(1): 672-8, 2015 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-25485691

RESUMO

Methane originating from biogas or natural gas is an attractive and environmentally friendly alternative to gasoline. Adsorption is seen as promising storage technology, but the heat released limits fast filling of these systems. Here a lab scale adsorptive methane storage tank, capable to study the temperature increase during fast filling, was realized. A variation of the filling time from 1 h to 31 s, showed a decrease of the storage capacity of 14% and temperature increase of 39.6 °C. The experimental data could be described in good accordance with a finite element simulation solving the transient mass, energy, and impulse balance. The simulation was further used to extrapolate temperature development in real sized car tanks and for different heat pipe scenarios, resulting in temperature rises of approximately 110 °C. It could be clearly shown, that with heat conductivity as solei mechanism the heat cannot be removed in acceptable time. By adding an outlet to the tank a feed flow cooling with methane as heat carrier was realized. This setup was proofed in simulation and lab scale experiments to be a promising technique for fast adsorbent cooling and can be crucial to leverage the full potential of adsorptive methane gas storage.


Assuntos
Temperatura Alta , Metano/análise , Adsorção , Temperatura Baixa , Simulação por Computador , Estudos de Viabilidade , Gases/análise , Gases/química , Metano/química , Reprodutibilidade dos Testes
11.
Front Zool ; 11: 28, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24812570

RESUMO

INTRODUCTION: Though it has long been known that the prosomal ganglion of scorpions is supplied by a dense system of arteries, the pattern of this network has never been described and analyzed in detail. Using MicroCT in combination with computer aided 3D-reconstruction we provide the first detailed description of the pattern of arteries in the prosomal ganglion of Brotheas granulatus (Scorpiones, Chactidae) and other scorpion species. RESULTS: The entire prosomal ganglion in scorpions is supplied by a network of arteries that branch off the major arteries of the anterior aorta system. The most prominent of these are the nine transganglionic arteries which run through the nerve mass along the midline of the body and branch terminally, i.e. below the neuropils, into smaller arteries. These arteries reticulate into a dense network between the surrounding somata and the centrally located neuropil structures of the ganglion. CONCLUSIONS: We demonstrate the presence in the prosomal ganglion of scorpions of a capillary system made up of afferent arteries which deliver hemolymph into the ganglion and efferent arteries which transport the hemolymph out of the ganglion. Adopting the structural definition used for vertebrate circulatory systems, this capillary network can also be termed a bipolar rete mirabile (located as it is between afferent and efferent arteries) analogous to those found in vertebrates and some echinoderms. Within the rete mirabile of the scorpion prosomal ganglion, some regions (i.e. neuropils) are better supplied than others. The structural information provided here can now be used in functional neuronal studies to determine the physiological and computational significance of the various neuropils in the complex scorpion nervous system.

12.
Chem Soc Rev ; 42(22): 8629-48, 2013 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-23753016

RESUMO

In this review, we introduce photonic crystal fibre as a novel optofluidic microdevice that can be employed as both a versatile chemical sensor and a highly efficient microreactor. We demonstrate that it provides an excellent platform in which light and chemical samples can strongly interact for quantitative spectroscopic analysis or photoactivation purposes. The use of photonic crystal fibre in photochemistry and sensing is discussed and recent results on gas and liquid sensing as well as on photochemical and catalytic reactions are reviewed. These developments demonstrate that the tight light confinement, enhanced light-matter interaction and reduced sample volume offered by photonic crystal fibre make it useful in a wide range of chemical applications.

13.
Transp Res Rec ; 2013(2389): 1-11, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24619314

RESUMO

Unlike other types of controlled intersections, drivers do not always comply with the "yield to pedestrian" sign at the roundabouts. This paper aims to identify the contributing factors affecting the likelihood of driver yielding to pedestrians at two-lane roundabouts. It further models the likelihood of driver yielding based on these factors using logistic regression. The models have been applied to 1150 controlled pedestrian crossings at entry and exit legs of two-lane approaches of six roundabouts across the country. The logistic regression models developed support prior research that the likelihood of driver yielding at the entry leg of roundabouts is higher than at the exit. Drivers tend to yield to pedestrians carrying a white cane more often than to sighted pedestrians. Drivers traveling in the far lane, relative to pedestrian location, have a lower probability of yielding to a pedestrian. As the speed increases the probability of driver yielding decreases. At the exit leg of the roundabout, drivers turning right from the adjacent lane have a lower propensity of yielding than drivers coming from other directions. The findings of this paper further suggest that although there has been much debate on pedestrian right-of-way laws and distinction between pedestrian waiting positions (in the street versus at the curb), this factor does not have a significant impact on driver yielding rate. The logistic regression models also quantify the effect of each of these factors on propensity of driver yielding. The models include variables which are specific to each study location and explain the impact size of each study location on probability of yielding. The models generated in this research will be useful to transportation professionals and researchers interested in understanding the factors that impact driver yielding at modern roundabouts. The results of the research can be used to isolate factors that may increase yielding (such as lower roundabout approach speeds), and can feasibly be incorporated into microsimulation algorithms to model driver yielding at roundabouts.

14.
Unfallchirurg ; 116(3): 213-20, 2013 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-23478898

RESUMO

Since the 1960s the ilioinguinal approach by Letournel with the three anatomic windows has been successfully established for the treatment of acetabular fractures involving predominantly the anterior column. The previous standard approach, the iliofemoral approach by Smith-Petersen, is still used for the therapy of anterior wall or isolated femoral head fractures. The increase in acetabular fractures in the elderly with lateral compression fractures after lateral falls, characterized by medial displacement of the quadrilateral plate and superomedial dome impaction, led to the use of the intrapelvic modified Stoppa approach with or without the first window of the ilioinguinal approach in the 1990s. To combine the advantages of the second and third windows of the ilioinguinal approach and the medial view of the modified Stoppa approach the Berne research group recently introduced the pararectus approach in acetabular surgery, which can be used as a less invasive acetabular surgical (LIAS) technique especially in the elderly.


Assuntos
Acetábulo/lesões , Acetábulo/cirurgia , Fixação Interna de Fraturas/instrumentação , Fixação Interna de Fraturas/métodos , Fraturas Ósseas/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos/instrumentação , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Humanos
15.
Unfallchirurg ; 116(3): 221-6, 2013 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-23478899

RESUMO

Posterior approaches to the hip joint were developed by Langenbeck and Kocher in the nineteenth century. Letournel created the term Kocher-Langenbeck approach which became one of the most important approaches to the hip joint. The further extension of this approach by digastric trochanteric osteotomy and subsequently by surgical hip dislocation enables visualization of the entire hip joint which allows complete evaluation of articular joint damage, quality of reduction and confirmation of extra-articular hardware. With the increasing incidence of acetabular fractures in the elderly there is a concomitant increase of complicating factors, such as multifragmentary posterior wall fractures, dome impaction, marginal impaction and femoral head damage. These factors are negative predictors and compromise a favorable outcome after acetabular surgery. With direct joint visualization these factors can be reliably recognized and corrected as adequately as possible. Surgical hip dislocation thus offers advantages in complex posterior wall, transverse and T-shaped fractures with or without posterior wall involvement. For these fracture types surgical hip dislocation represents a standard approach in our hands.


Assuntos
Acetábulo/lesões , Acetábulo/cirurgia , Fixação Interna de Fraturas/instrumentação , Fixação Interna de Fraturas/métodos , Fraturas Ósseas/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos/instrumentação , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Humanos
16.
Trauma Case Rep ; 43: 100771, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36647437

RESUMO

The highest instability in fragility fractures of the pelvis (FFP) is noted in presence of H-, U-type sacral fractures. Suggested surgical treatment options include uni- or bilateral sacroiliac or transsacral screw fixation at different levels or in combination, as well as lumbopelvic and bilateral triangular lumbopelvic stabilization. However, distinct treatment recommendations for this subset of injuries are scarce. We present a case sustaining rapid FFP crescendo instability following initial conservative treatment of a FFP type II injury resulting in a U-type spinopelvic dissociation. Fixation using one percutaneous cement augmented transsacral S1 screw resulted in perpetual clinical improvements in pain and mobility in presence of radiologic fracture consolidation.

17.
ACS Appl Mater Interfaces ; 15(15): 18781-18789, 2023 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-37024101

RESUMO

Non-precious metal catalysts show great promise to replace the state-of-the-art Pt-based catalysts for catalyzing the oxygen reduction reaction (ORR), while their catalytic activity still needs to be greatly improved before their broad-based application. Here, we report a facile approach to improving the performance of zeolitic imidazolate framework-derived carbon (ZDC) toward the ORR by incorporating a small amount of ionic liquid (IL). The IL would preferentially fill the micropores of ZDC and greatly enhance the utilization of the active sites within the micropores, which are initially not accessible due to insufficient surface wetting. It is also disclosed that the ORR activity in terms of kinetic current at 0.85 V depends on the loading amount of the IL, and the maximum activity is obtained at a mass ratio of IL to ZDC at 1.2. The optimum stems from the counterbalance between the enhanced utilization of the active sites within the micropores and the retarded diffusion of the reactants within the IL phase due to its high viscosity.

18.
ACS Appl Mater Interfaces ; 15(13): 16714-16722, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36961995

RESUMO

Selective oxidation reactions are an important class of the current chemical industry and will be highly important for future sustainable chemical production. Especially, the selective oxidation of primary alcohols is expected to be of high future interest, as alcohols can be obtained on technical scales from biomass fermentation. The oxidation of primary alcohols produces aldehydes, which are important intermediates. While selective methanol oxidation is industrially established, the commercial catalyst suffers from deactivation. Ethanol selective oxidation is not commercialized but would give access to sustainable acetaldehyde production when using renewable ethanol. In this work, it is shown that employing 2D MXenes as building blocks allows one to design a nanostructured oxide catalyst composed of mixed valence vanadium oxides, which outperforms on both reactions known materials by nearly an order of magnitude in activity, while showing high selectivity and stability. The study shows that the synthesis route employing 2D materials is key to obtain these attractive catalysts. V4C3Tx MXene structured as an aerogel precursor needs to be employed and mildly oxidized in an alcohol and oxygen atmosphere to result in the aspired nanostructured catalyst composed of mixed valence VO2, V6O13, and V3O7. Very likely, the bulk stable reduced valence state of the material together coupled with the nanorod arrangement allows for unprecedented oxygen mobility as well as active sites and results in an ultra-active catalyst.

19.
ChemistryOpen ; 11(10): e202200171, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36200517

RESUMO

The Kolbe electrolysis is a promising reaction to combine the usage of electrons as reagents and the application of renewable generated carboxylic acids as raw materials producing value added chemicals. Within this study, the electrolysis was conducted in a specially developed concept electrochemical microreactor and draws the particular attention to continuous operation and reuse of the aqueous electrolyte as well as of the dissolved unreacted feedstock. The electrolysis was conducted in alkaline aqueous solution using n-octanoic acid as model substance. Platinized titanium as anode material in an undivided cell setup was shown to give Kolbe selectivity above 90 %. During the technically relevant conditions of current densities up to 0.6 A cm-2 and overall electrolysis times of up to 3 h, a high electrode stability was observed. Finally, a proof-of-concept continuous operation and the numbering up potential of the ECMR could be demonstrated.


Assuntos
Caprilatos , Ácidos Carboxílicos , Eletrólise , Eletrólitos , Titânio/química
20.
Nat Med ; 4(7): 775-80, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9662367

RESUMO

Adenosine deaminase-deficient severe combined immunodeficiency was the first disease investigated for gene therapy because of a postulated production or survival advantage for gene-corrected T lymphocytes, which may overcome inefficient gene transfer. Four years after three newborns with this disease were given infusions of transduced autologous umbilical cord blood CD34+ cells, the frequency of gene-containing T lymphocytes has risen to 1-10%, whereas the frequencies of other hematopoietic and lymphoid cells containing the gene remain at 0.01-0.1%. Cessation of polyethylene glycol-conjugated adenosine deaminase enzyme replacement in one subject led to a decline in immune function, despite the persistence of gene-containing T lymphocytes. Thus, despite the long-term engraftment of transduced stem cells and selective accumulation of gene-containing T lymphocytes, improved gene transfer and expression will be needed to attain a therapeutic effect.


Assuntos
Adenosina Desaminase/imunologia , Antígenos CD34/imunologia , Transplante de Células-Tronco Hematopoéticas , Linfócitos T/imunologia , Imunologia de Transplantes/imunologia , Adenosina Desaminase/deficiência , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Animais , Animais Recém-Nascidos , Linhagem Celular , Citometria de Fluxo , Frequência do Gene , Granulócitos/imunologia , Humanos , Leucócitos Mononucleares/imunologia , Contagem de Linfócitos , Camundongos , Camundongos SCID , Polietilenoglicóis , Linfócitos T/efeitos dos fármacos , Transformação Genética , Transplante Autólogo , Cordão Umbilical
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