RESUMEN
The ongoing efforts to optimize rechargeable Li-ion batteries led to the interest in intercalation of nanoscale layered compounds, including bilayer graphene. Its lithium intercalation has been demonstrated recently but the mechanisms underpinning the storage capacity remain poorly understood. Here, using magnetotransport measurements, we report in-operando intercalation dynamics of bilayer graphene. Unexpectedly, we find four distinct intercalation stages that correspond to well-defined Li-ion densities. Transitions between the stages occur rapidly (within 1 sec) over the entire device area. We refer to these stages as 'in-plane', with no in-plane analogues in bulk graphite. The fully intercalated bilayers represent a stoichiometric compound C14LiC14 with a Li density of â¼2.7·1014 cm-2, notably lower than fully intercalated graphite. Combining the experimental findings and DFT calculations, we show that the critical step in bilayer intercalation is a transition from AB to AA stacking which occurs at a density of â¼0.9·1014 cm-2. Our findings reveal the mechanism and limits for electrochemical intercalation of bilayer graphene and suggest possible avenues for increasing the Li storage capacity.
RESUMEN
Muscle weakness is a common symptom in CKD patients, and the pathway by which secondary hyperparathyroidism (SHPT) affects muscle function is unknown. Osteopontin (OPN), a bone matrix protein stimulated by PTH and phosphate, has been associated with inflammatory muscle diseases. In this observational and prospective cohort study, we evaluated 30 patients with severe SHPT (39 ± 12 yr; 18 women), before and 6 mo after parathyroidectomy (PTx). We examined the relationships among CKD-mineral and bone disorder parameters; myokine and inflammatory cytokine levels; and changes in resting energy expenditure (REE), muscle function, BMD, and muscle-related proteins. At baseline, the patients showed low gene expression of muscle turnover markers and irisin, as well as high protein expression of OPN, transforming growth factor beta (TGF-ß), and fibroblast growth factor 21. Six months after PTx, REE and muscle mass had not changed, but physical performance, muscle strength, and bone mass improved, more so in patients undergoing total PTx. Also, there were reductions in the protein expression of OPN (11 vs 3%, p=.01) and TGF-ß (21 vs 7%, p=.002) in muscle, together with a significant increase in irisin muscular levels (30 vs 35 pg/mg, p=.02). The gain in bone mass and the increase in irisin levels correlated with a reduction in PTH. The levels of interleukin (IL)-1ß, tumor necrosis factor alpha, and IL-17 (markers of myositis) were also lower after PTx. Our data suggest that SHPT plays a role in CKD-induced muscle dysfunction, indirectly, via release of bone-specific proteins, which is partially reverted with PTx.
RESUMEN
Quantum cutting (QC) allows the conversion of high-energy photons into lower-energy photons, exhibiting great potential for infrared communications. Yb-doped perovskite nanocrystals can achieve an efficient QC process with extremely high photoluminescence quantum yield (PLQY) thanks to the favorable Yb3+ incorporation in the perovskite structure. However, conventionally used oleic acid-oleylamine-based ligand pairs cause instability issues due to highly dynamic binding to surface states that have curbed their potential applications. Herein, zwitterionic type C3-sulfobetaine 3-(N,N-Dimethylpalmitylammonio)propanesulfonate molecule is utilized to build a strong binding state on the nanocrystals' surface through a new phosphine oxide synthesis route. Leveraging machine learning and Bayesian Optimization workflow to determine optimal synthesis conditions, near-infrared PLQY above 190% is achieved. The high PLQY is well maintained after over three months of aging, under high-flux continuous UV irradiation, and long continuous annealing. This is the first report of highly efficient and stable perovskite quantum cutters, which will drive the study of fundamental physics phenomena and near-infrared quantum communications.
RESUMEN
Anterior cruciate ligament (ACL) injury is one of the main injuries in professional and amateur athletes of different sports. Hundreds of thousands of ACL ruptures occurs annually, and only 55% of the athletes return to competitive level, with a 15 times higher chance of suffering a second injury. 60% of these injuries occur without physical contact and since they occur in the acute process, they can cause joint effusion, muscle weakness and functional incapacity. In the long term, they can contribute to a premature process of osteoarthritis. This narrative review is of particular interest for clinicians, practitioners, coaches and athletes to understand the main factors that contribute to an injury and/or re-injury and thus, to optimize their training to reduce and/or prevent the risk of injury and/or reinjury of ACL. Therefore, we aimed reports a narrative overview of the literature surrounding communication and explore through a theoretical review, the main risk factors for an ACL injury and/or re-injury, as well as bringing practical and correct methods of training applications. The lack of theoretical/practical knowledge on the part of rehabilitation and/or training professionals may impair the treatment of an athlete and/or student. High-quality research that can testing different training methods approaches in randomized controlled trials is needed.
Asunto(s)
Lesiones del Ligamento Cruzado Anterior , Traumatismos en Atletas , Lesiones de Repetición , Humanos , Factores de Riesgo , Volver al DeporteRESUMEN
The instability of erythropoietin receptor agonists (ERAs, i.e., EPO) in urine presents a challenge to their detectability in doping control samples; however, this issue is not often seen in blood (serum) samples. With the anti-doping field beginning to transition into alternative blood collection technologies, it is important to understand recombinant EPO (rEPO) detectability in serum samples collected from one such capillary collection device, the Tasso+ SST. Twelve individuals were administered a single, 40 IU/kg dose of rEPO (epoetin alfa, EPOGEN®). Following administration, matched urine, venous serum, and capillary serum samples were concurrently collected. Urine aliquots were subject to various storage times and temperatures mimicking shipping conditions of doping control urine samples to assess EPO stability, while other urine aliquots, venous serum, and capillary serum aliquots were frozen until analysis to understand rEPO detectability across all three matrices. EPO and rEPO instability was identified in urine collected from 8 of 12 participants, especially in aliquots stored at room temperature and 37°C. In some of these unstable samples, rEPO was still detectable, while in others, no recombinant nor endogenous EPO was detectable and would have resulted in negative sample reports. Analyzing the concurrently collected urine, venous, and capillary serum samples, rEPO detectability was identical across the three matrices. In most cases, rEPO was detectable for at least 168 h post-administration. Noting greater stability in blood compared with urine, it is recommended that anti-doping authorities utilize this novel capillary serum collection technology to improve overall ERA detectability in doping control samples.
RESUMEN
Strawberries are a nutrient dense food rich in vitamins, minerals, non-nutrient antioxidant phenolics, and fibers. Strawberry fiber bioactive structures are not well characterized and limited information is available about the interaction between strawberry fiber and phenolics. Therefore, we analyzed commercial strawberry pomace in order to provide a detailed carbohydrate structural characterization, and to associate structures with functions. The pomace fraction, which remained after strawberry commercial juice extraction, contained mostly insoluble (49.1 % vs. 5.6 % soluble dietary fiber) dietary fiber, with pectin, xyloglucan, xylan, ß-glucan and glucomannan polysaccharides; glucose, fructose, xylose, arabinose, galactose, fucose and galacturonic acid free carbohydrates; protein (15.6 %), fat (8.34 %), and pelargonidin 3-glucoside (562 µg/g). Oligosaccharides from fucogalacto-xyloglucan, methyl-esterified rhamnogalacturonan I with branched arabinogalacto-side chains, rhamnogalacturonan II, homogalacturonan and ß-glucan were detected by MALDI-TOF MS, NMR and glycosyl-linkage analysis. Previous reports suggest that these oligosaccharide and polysaccharide structures have prebiotic, bacterial pathogen anti-adhesion, and cholesterol-lowering activity, while anthocyanins are well-known antioxidants. A strawberry pomace microwave acid-extracted (10 min, 80 °C) fraction had high molar mass (2376 kDa) and viscosity (3.75 dL/g), with an extended rod shape. A random coil shape, that was reported previously to bind to phenolic compounds, was observed for other strawberry microwave-extracted fractions. These strawberry fiber structural details suggest that they can thicken foods, while the polysaccharide and polyphenol interaction indicates great potential as a multiple-function bioactive food ingredient important for gut and metabolic health.
RESUMEN
Electronic spectra of solids subjected to a magnetic field are often discussed in terms of Landau levels and Hofstadter-butterfly-style Brown-Zak minibands manifested by magneto-oscillations in two-dimensional electron systems. Here, we present the semiclassical precursors of these quantum magneto-oscillations which appear in graphene superlattices at low magnetic field near the Lifshitz transitions and persist at elevated temperatures. These oscillations originate from Aharonov-Bohm interference of electron waves following open trajectories that belong to a kagome-shaped network of paths characteristic for Lifshitz transitions in the moire superlattice minibands of twistronic graphenes.
RESUMEN
Biological nanostructures change their shape and function in response to external stimuli, and significant efforts have been made to design artificial biomimicking devices operating on similar principles. In this work we demonstrate a programmable nanofluidic switch, driven by elastocapillarity, and based on nanochannels built from layered two-dimensional nanomaterials possessing atomically smooth surfaces and exceptional mechanical properties. We explore operational modes of the nanoswitch and develop a theoretical framework to explain the phenomenon. By predicting the switching-reversibility phase diagram-based on material, interfacial and wetting properties, as well as the geometry of the nanofluidic circuit-we rationally design switchable nano-capsules capable of enclosing zeptoliter volumes of liquid, as small as the volumes enclosed in viruses. The nanoswitch will find useful application as an active element in integrated nanofluidic circuitry and could be used to explore nanoconfined chemistry and biochemistry, or be incorporated into shape-programmable materials.
RESUMEN
Antiaromatic cyclobutadiene (c-C4H4) is the simplest prototype of [n]annulenes and a key reactive intermediate with significant ring strain, serving as the model compound for antiaromatic systems in organic chemistry. Here, we report the first bottom-up formation of cyclobutadiene in low-temperature acetylene (C2H2) ices exposed to energetic electrons. Cyclobutadiene was isolated and detected in the gas phase upon sublimation utilizing vacuum ultraviolet photoionization reflectron time-of-flight mass spectrometry along with ultraviolet photolysis studies. These findings advance our fundamental understanding of the exotic chemistry and preparation of highly strained antiaromatic cycles through non-equilibrium chemistry in interstellar environments, thus affording a possible route for the formation of highly strained molecules such as the hitherto elusive tetrahedrane (C4H4). Because acetylene is a major product of the photolysis and radiolysis of methane (CH4) ice, an abundant component of interstellar ices, our results suggest that cyclobutadiene can likely be formed in methane-rich ices of cold molecular clouds.
RESUMEN
INTRODUCTION: A musculoskeletal disorder (MSD) of pain, weakness, numbness, or paresthesia is a common issue for dental health care providers. The aims of this study were to (1) identify the prevalence of MSDs among endodontists in the United States, (2) to identify risk factors of MSDs among United States endodontists, and (3) to compare these findings with other published findings for dental providers. METHODS: A 24-question survey regarding the demographics, potential risk factors, and prevalence of MSDs was formulated and distributed to 5394 members of the American Association of Endodontists. Data were then analyzed using descriptive statistics and chi-square analysis to find significance at α = 0.05. RESULTS: Six hundred twenty participants responded to the survey for an overall response rate of 12%. Of the submitted surveys, 527 of them confirmed to be endodontists practicing in the United States, and all results were derived from those 527 surveys. Seventy-four percent of respondents reported having experienced MSDs in the last 12 months, and 88% reported having experienced at least 1 MSD thus far during their career. Eighty-five percent of female participants reported an MSD within the past 12 months compared with 70% of males. CONCLUSIONS: MSDs have a high prevalence among endodontists in the United States. The neck and lower back were the areas of highest MSD prevalence. Female sex and the frequent adoption of awkward postures were factors associated with significantly higher rates of reported MSDs in the last 12 months.
Asunto(s)
Endodoncistas , Dolor Musculoesquelético , Enfermedades Profesionales , Masculino , Humanos , Estados Unidos/epidemiología , Femenino , Dolor Musculoesquelético/complicaciones , Prevalencia , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/etiología , Encuestas y Cuestionarios , Factores de RiesgoRESUMEN
In nature and technologies, many chemical reactions occur at interfaces with dimensions approaching that of a single reacting species in nano- and angstrom-scale. Mechanisms governing reactions at this ultimately small spatial regime remain poorly explored because of challenges to controllably fabricate required devices and assess their performance in experiment. Here we report how efficiency of electrochemical reactions evolves for electrodes that range from just one atom in thickness to sizes comparable with and exceeding hydration diameters of reactant species. The electrodes are made by encapsulating graphene and its multilayers within insulating crystals so that only graphene edges remain exposed and partake in reactions. We find that limiting current densities characterizing electrochemical reactions exhibit a pronounced size effect if reactant's hydration diameter becomes commensurable with electrodes' thickness. An unexpected blockade effect is further revealed from electrodes smaller than reactants, where incoming reactants are blocked by those adsorbed temporarily at the atomically narrow interfaces. The demonstrated angstrom-scale electrochemistry offers a venue for studies of interfacial behaviors at the true molecular scale.
RESUMEN
Imines play a fundamental role in organic synthesis and some of them have been detected in space. However, the simplest imines are spectroscopically not well-characterized. Herein we present the infrared and UV/Vis spectroscopic characterization of 2-iminoacetaldehyde using cryogenic matrix isolation techniques. After UV irradiation of 2-azidoacetaldehyde in solid argon at 3 K we identified two conformers of 2-iminoacetaldehyde, which can be photochemically interconverted. Deuterium labelling experiments and high level ab initio coupled cluster calculations at the CCSD(T)/CBS level of theory provide further evidence for the formation of 2-iminoacetaldehyde.
RESUMEN
The Athlete Biological Passport (ABP) is a longitudinal tool used in anti-doping to monitor biological parameters known to change with performance-enhancing drug use. The ABP consists of multiple modules, including two aimed at detecting the use of endogenous anabolic androgenic steroids: the urinary and serum steroid modules. Human chorionic gonadotropin (hCG) is a protein hormone potentially abused by male athletes to increase the production of endogenous testosterone. To date, no studies have investigated the impact of extended hCG administration on the urinary and serum steroid modules of the ABP. The goal of this study was to identify the impact of multiple hCG administrations on the parameters tracked as part of the urinary and serum steroid modules of the ABP. Ten recreationally active, healthy male individuals self-administered seven 250 µg hCG injections over 3 weeks. Serum and urine samples were collected before, during, and 2 weeks following the final injection. All ABP parameters were quantified in the respective matrix, and steroid profiles were created with Anti-Doping Administration and Management System adaptive model upper and lower limits for both matrices. In both serum and urine profiles, testosterone increased; however, the testosterone/epitestosterone ratio in urine and the testosterone/androstenedione ratio in serum showed minimal changes. Additionally, serum luteinizing hormone (LH) was quantified using an immunoassay, and a serum testosterone/LH ratio was generated. Serum LH values decreased during administration causing large increases in the serum T/LH ratio, indicating this ratio may be a more sensitive parameter for detecting hCG abuse than urinary testosterone/epitestosterone or serum testosterone/androstenedione.
Asunto(s)
Doping en los Deportes , Epitestosterona , Humanos , Masculino , Epitestosterona/orina , Androstenodiona , Testosterona/orina , Atletas , Esteroides/orina , Hormona Luteinizante/orina , Gonadotropina Coriónica/orina , Detección de Abuso de SustanciasRESUMEN
OBJECTIVE: Thermophilin 110, a bacteriocin produced by Streptococcus thermophilus B59671, inhibited planktonic growth and biofilm formation of Cutibacterium acnes, a commensal skin bacterium associated with the inflammatory disease, acne vulgaris, and more invasive deep tissue infections. RESULTS: Thermophilin 110 prevented planktonic growth of C. acnes at a concentration ≥ 160 AU mL-1; while concentrations ≥ 640 AU mL-1 resulted in a > 5 log reduction in viable planktonic cell counts and inhibited biofilm formation. Arabinoxylan (AX) and sodium alginate (SA) hydrogels were shown to encapsulate thermophilin 110, but as currently formulated, the encapsulated bacteriocin was unable to diffuse out of the gel and inhibit the growth of C. acnes. Hydrogels were also used to encapsulate S. thermophilus B59671, and inhibition zones were observed against C. acnes around intact SA gels, or S. thermophilus colonies that were released from AX gels. CONCLUSIONS: Thermophilin 110 has potential as an antimicrobial for preventing C. acnes infections and further optimization of SA and AX gel formulations could allow them to serve as delivery systems for bacteriocins or bacteriocin-producing probiotics.
Asunto(s)
Bacteriocinas , Piel , Alginatos , Bacteriocinas/farmacología , Agregación Celular , HidrogelesRESUMEN
CONTEXT: A unit supported by Médecins Sans Frontières (MSF) cares for patients with advanced HIV at Donka National Hospital, Conakry, Guinea. OBJECTIVE: To determine the factors associated with the occurrence of death in patients hospitalised in the unit between 2017 and 2021. DESIGN: This was a retrospective analysis of routine data from patients hospitalised with advanced HIV. RESULTS: A total of 3,718 patients were included, with a median age of 40 years (IQR 33-51), of whom 2,241 (60.3%) were women. The mean mortality rate was 33.6% (n = 1,240), down from 40% in 2017 to 29% in 2021, but this was not statistically significant. The period most at risk of death was the first 25 days of hospitalisation. Among these patients, TB (43.8%) and toxoplasmosis (11.4%) were the most frequent diagnoses. After multivariate analysis using Cox regression, the factors associated with death were age 25-49 years (adjusted hazard ratio [aHR] 1.60; P = 0.002) or ≥50 years (aHR 1.80; P < 0.001), the presence of respiratory (aHR 1.23; P = 0.001) or abdominal symptoms (aHR 1.26; P < 0.001) and readmission (aHR 0.54; P < 0.001). CONCLUSION: Patients aged 25-49 years or older, or those presenting with respiratory or abdominal signs require increased surveillance, as they are at the greatest risk of dying from the disease, especially during the first 25 days of hospitalisation.
RESUMEN
Enols - tautomers of ketones or aldehydes - are anticipated to be ubiquitous in the interstellar medium and play a key role in the formation of complex organic molecules in deep space, but their fundamental formation mechanisms have remained largely elusive as of now. Here we present a combined experimental and computational study demonstrating the first preparation of propen-2-ol (CH3C(OH)CH2) and its isomer methyl vinyl ether (CH3OCHCH2) in low-temperature acetone (CH3COCH3) ices upon exposure to energetic electrons. Propen-2-ol is the simplest enol tautomer of a ketone. Exploiting tunable vacuum ultraviolet photoionization in conjunction with reflectron time-of-flight mass spectrometry, propen-2-ol and methyl vinyl ether were monitored in the gas phase upon sublimation during the temperature-programmed desorption process suggesting that both isomers are promising candidates for future astronomical searches such as via the James Webb Space Telescope. Electronic structure calculations reveal that the barrier of keto-enol tautomerization can be reduced by more than a factor of two (162 kJ mol-1) through the involvement of solvating water molecules under realistic conditions on interstellar grains. The implicit solvent effects, i.e., the influences of the solvent dipole field on the barrier height are found to be minimal and do not exceed 10 kJ mol-1. Our findings signify a crucial step toward a better understanding of the enolization of ketones in the interstellar medium thus constraining the molecular structures and complexity of molecules that form in extraterrestrial ices - ketones - through non-equilibrium chemistry.
RESUMEN
Sugars and sugar-related molecules are ubiquitous in carbonaceous meteorites and in star-forming regions, but the underlying mechanisms of their formation have remained largely elusive. Herein, we report an unconventional synthesis of the hemiacetal, (R/S)-1-methoxyethanol (CH3OCH(OH)CH3), through quantum tunneling mediated reactions in low-temperature interstellar model ices composed of acetaldehyde (CH3CHO) and methanol (CH3OH). The detection of racemic 1-methoxyethanol through a bottom-up synthesis from simple, abundant precursor molecules within interstellar ices represents a vital starting point to the formation of complex interstellar hemiacetals. Once synthesized, hemiacetals may act as possible precursors to interstellar sugars and sugar-related molecules in deep space.
RESUMEN
Febrile seizures during early childhood are a relevant risk factor for the development of mesial temporal lobe epilepsy. Nevertheless, the molecular mechanism induced by febrile seizures that render the brain susceptible or not-susceptible to epileptogenesis remain poorly understood. Because the temporal investigation of such mechanisms in human patients is impossible, rat models of hyperthermia-induced febrile seizures have been used for that purpose. Here we conducted a temporal analysis of the transcriptomic and microRNA changes in the ventral CA3 of rats that develop (HS group) or not-develop (HNS group) seizures after hyperthermic insult on the eleventh postnatal day. The selected time intervals corresponded to acute, latent, and chronic phases of the disease. We found that the transcriptional differences between the HS and the HNS groups are related to inflammatory pathways, immune response, neurogenesis, and dendritogenesis in the latent and chronic phases. Additionally, the HNS group expressed a greater number of miRNAs (some abundantly expressed) as compared to the HS group. These results indicate that HNS rats were able to modulate their inflammatory response after insult, thus presenting better tissue repair and re-adaptation. Potential therapeutic targets, including genes, miRNAs and signaling pathways involved in epileptogenesis were identified.
Asunto(s)
Hipertermia Inducida , MicroARNs , Convulsiones Febriles , Humanos , Preescolar , Ratas , Animales , Convulsiones Febriles/genética , Transcriptoma , Hipocampo , MicroARNs/genética , Susceptibilidad a EnfermedadesRESUMEN
BACKGROUND: Human chorionic gonadotropin (hCG) detection is indicative of pregnancy and can be indicative of some forms of cancerous tumors. The hCG drug itself, however, is a performance enhancing substance used by male athletes to increase testosterone production. Antidoping testing for hCG is conducted in urine, often on immunoanalyzer platforms, many of which utilize biotin-streptavidin dependent immunoassays in which the presence of biotin in samples is a known confounding factor. While biotin interference in serum has been well-studied, the extent of biotin interference in urine has not. METHODS: Ten active male individuals underwent a 2-week hCG administration protocol concurrent with supplementation with biotin (20 mg/day) or placebo. Urine and serum samples were collected throughout the study and analyzed for hCG and biotin concentrations. RESULTS: Urinary biotin levels in the hCG + biotin group increased 500-fold over baseline and 29-fold over corresponding serum biotin levels after biotin supplementation. When using a biotin-dependent immunoassay, the hCG + placebo group produced hCG-positive results (hCG ≥ 5 mIU/mL) in 71% of urine samples, while the hCG + biotin group produced positive results in only 19% of samples. Both groups had elevated hCG values in serum measurements by a biotin-dependent immunoassay and in urine when using a biotin-independent immunoassay. Urinary hCG measurements and biotin levels from the hCG + biotin group showed a negative correlation (Spearman r = -0.46, P < 0.0001) when measured using a biotin-dependent immunoassay. CONCLUSIONS: Biotin supplementation can severely suppress urinary hCG values in assays utilizing biotin-streptavidin binding methods and therefore these types of assays are not recommended for use in urine samples containing high levels of biotin. Clinicaltrials.gov Registration Number: NCT05450900.