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1.
Nature ; 627(8003): 301-305, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38448596

RESUMEN

Solid-state Li-S batteries (SSLSBs) are made of low-cost and abundant materials free of supply chain concerns. Owing to their high theoretical energy densities, they are highly desirable for electric vehicles1-3. However, the development of SSLSBs has been historically plagued by the insulating nature of sulfur4,5 and the poor interfacial contacts induced by its large volume change during cycling6,7, impeding charge transfer among different solid components. Here we report an S9.3I molecular crystal with I2 inserted in the crystalline sulfur structure, which shows a semiconductor-level electrical conductivity (approximately 5.9 × 10-7 S cm-1) at 25 °C; an 11-order-of-magnitude increase over sulfur itself. Iodine introduces new states into the band gap of sulfur and promotes the formation of reactive polysulfides during electrochemical cycling. Further, the material features a low melting point of around 65 °C, which enables repairing of damaged interfaces due to cycling by periodical remelting of the cathode material. As a result, an Li-S9.3I battery demonstrates 400 stable cycles with a specific capacity retention of 87%. The design of this conductive, low-melting-point sulfur iodide material represents a substantial advancement in the chemistry of sulfur materials, and opens the door to the practical realization of SSLSBs.

2.
PLoS Biol ; 21(10): e3002344, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37906610

RESUMEN

Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential growth patterns, with the east sides of stems growing more during the day and the west sides of stems growing more at night. This process, termed heliotropism, is generally believed to be a specialized form of phototropism; however, the underlying mechanism is unknown. To better understand heliotropism, we compared gene expression patterns in plants undergoing phototropism in a controlled environment and in plants initiating and maintaining heliotropic growth in the field. We found the expected transcriptome signatures of phototropin-mediated phototropism in sunflower stems bending towards monochromatic blue light. Surprisingly, the expression patterns of these phototropism-regulated genes are quite different in heliotropic plants. Most genes rapidly induced during phototropism display only minor differences in expression across solar tracking stems. However, some genes that are both rapidly induced during phototropism and are implicated in growth responses to foliar shade are rapidly induced on the west sides of stems at the onset of heliotropism, suggesting a possible role for red light photoreceptors in solar tracking. To test the involvement of different photoreceptor signaling pathways in heliotropism, we modulated the light environment of plants initiating solar tracking. We found that depletion of either red and far-red light or blue light did not hinder the initiation or maintenance of heliotropism in the field. Together, our results suggest that the transcriptional regulation of heliotropism is distinct from phototropin-mediated phototropism and likely involves inputs from multiple light signaling pathways.


Asunto(s)
Proteínas de Arabidopsis , Helianthus , Helianthus/metabolismo , Fototropinas/metabolismo , Luz Solar , Luz , Fototropismo/fisiología , Transducción de Señal , Proteínas de Arabidopsis/metabolismo
3.
Aviat Space Environ Med ; 85(8): 857-62, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25199130

RESUMEN

BACKGROUND: Helicopter underwater escape training (HUET) carries a potential for injury and this paper identifies the injury rate. METHOD: A marine survival training school registry of all students trained between 2005-2012 in HUET and the coinciding accident records were examined. RESULTS: There were 8902 students trained in a helicopter underwater escape simulator for a total of 59,245 underwater escapes. There were 40 cases where only first-aid was required and 3 serious injuries (a laceration requiring 5 sutures, 1 dislocated shoulder, and 1 water aspiration requiring hospitalization). There were no deaths and no problems reported with using the Emergency Breathing System (EBS) or Air Pocket. Of the injuries, 11 were due to the student using a poor escape technique. The overall probability of injury was 0.74 per 1000 ascents. CONCLUSIONS: In HUET training, there is a very low injury rate with almost no significant severity. Although not scientifically proven, this would suggest that the low incident rate is due to good medical screening and the attention given by instructors to anxious students. Compared to other training such as diving, parachute jumping, and submarine escape training, the rate of injury was considerably lower.


Asunto(s)
Accidentes de Aviación/estadística & datos numéricos , Aeronaves , Aviación/educación , Sobrevida , Agua , Heridas y Lesiones/epidemiología , Adulto , Femenino , Humanos , Inmersión/efectos adversos , Masculino , Nueva Escocia/epidemiología , Factores de Riesgo , Heridas y Lesiones/etiología
4.
Aviat Space Environ Med ; 85(4): 440-4, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24754206

RESUMEN

INTRODUCTION: According to 40 yr of data, the fatality rate for a helicopter crash into water is approximately 25%. Does warning time and the final position of the helicopter in the water influence the survival rate? METHODS: The National Transportation Safety Board (NTSB) database was queried to identify helicopter crashes into water between 1981 and 2011 in the Gulf of Mexico and Hawaii. Fatality rate, amount of warning time prior to the crash, and final position of the helicopter were identified. RESULTS: There were 133 helicopters that crashed into water with 456 crew and passengers. Of these, 119 occupants (26%) did not survive; of those who did survive, 38% were injured. Twelve died after making a successful escape from the helicopter. Crashes with < 15 s warning had a fatality rate of 22%, compared to 12% for 16-60 s warning and 5% for > 1 min. However, more than half of fatalities (57%) came from crashes for which the warning time could not be determined. DISCUSSION: Lack of warning time and how to survive in the water after the crash should be a topic for study in all marine survival/aircraft ditching courses. Investigators should be trained to provide estimates of warning time when investigating helicopter crashes into water.


Asunto(s)
Accidentes de Aviación/mortalidad , Medicina Aeroespacial , Aeronaves , Agua , Accidentes de Aviación/estadística & datos numéricos , Golfo de México , Hawaii , Humanos , Factores de Riesgo , Tasa de Supervivencia , Factores de Tiempo
5.
J Craniofac Surg ; 20(1): 93-7, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19165000

RESUMEN

We demonstrate a novel method of endoscopic frontal-orbital advancement for the treatment of unicoronal craniosynostosis. The evolution of this cranioplasty modality burrows from an established precedent of safety and technical experience in strip craniectomies and endoscopic brow surgery. The procedure facilitates osteotomies similar to open frontal-orbital advancement and uses reabsorbable materials to achieve immediate intraoperative correction of unicoronal craniosynostosis through smaller incisions. The patients in the study underwent endoscopic frontal-orbital advancement and cranial vault remodeling. This was made possible with the use of a novel ultrasonic bone saw that permits osteotomies to be made with minimal disruption to the dura matter. After full frontal-orbital advancement, immediate reabsorbable fixation was used to stabilize the advancement as in the open technique. There were no major complications. All patients demonstrated improvement in plagiocephaly due to unilateral coronal synostosis. Patients and their families reported a 100% patient satisfaction and an improvement in cranial asymmetry from 10 to 2 mm (P < 0.5). This is a new endoscopic cranial vault remolding technique that achieves state-of-the-art correction of unicoronal craniosynostosis with less morbidity and mortality.


Asunto(s)
Craneosinostosis/cirugía , Endoscopía/métodos , Procedimientos de Cirugía Plástica/métodos , Implantes Absorbibles , Craneotomía/instrumentación , Craneotomía/métodos , Endoscopios , Estudios de Seguimiento , Hueso Frontal/anomalías , Hueso Frontal/cirugía , Humanos , Lactante , Masculino , Procedimientos Quirúrgicos Mínimamente Invasivos/instrumentación , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Órbita/cirugía , Dispositivos de Fijación Ortopédica , Hueso Parietal/anomalías , Satisfacción del Paciente , Procedimientos de Cirugía Plástica/instrumentación , Hueso Temporal/cirugía , Resultado del Tratamiento , Terapia por Ultrasonido/instrumentación
6.
Aerosp Med Hum Perform ; 90(2): 135-138, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30670125

RESUMEN

INTRODUCTION: In February 1970, halfway through a Polaris submarine war patrol in SSBN-02 HMS Renown (port crew), a Petty Officer presented to the sick bay in excruciating pain with a broken upper left molar tooth. The zinc oxide/clove oil mixture would not stick on to the vertical face of the fracture. In preparation for such events, Royal Navy (RN) submarine medical officers are taught excellent fundamental dental skills. In this case, it seemed a very difficult job to extract the remains of the tooth. The author reports the first known use of glass fiber/resin in the RN to crown and treat a fractured molar, cover the root, and save the tooth, and to recommend that all military and civilian medical staff working anywhere in isolation with no dental facility locally be given similar training to that which RN submarine medical officers receive before being sent on extended dives.Brooks CJ. Fractured tooth stabilized with auto body repair resin on a 1970 Royal Navy Polaris submarine patrol. Aerosp Med Hum Perform. 2019; 90(2):135-138.


Asunto(s)
Navíos/historia , Fracturas de los Dientes/historia , Historia del Siglo XX , Humanos , Personal Militar , Reino Unido
7.
Chem Commun (Camb) ; (32): 3777-9, 2008 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-18685774

RESUMEN

The size of iron oxide nanoparticles, prepared from the thermal decomposition of Fe(CO)(5) in a high boiling solvent in the presence of oleic acid, is affected by water concentration, giving particles from sizes of 5.6 nm to as low as 2.2 nm.

8.
Arthroscopy ; 24(7): 796-804, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18589268

RESUMEN

PURPOSE: The purpose of our study was to evaluate the complications, technique-related risks, and the clinical course of patients treated with high tibial osteotomy (HTO) for medial arthritis of the knee with varus malalignment. METHODS: Forty-three of 46 consecutive patients (follow-up, 93.5%) treated with HTO using the TomoFix implant (Synthes, Solothurn, Switzerland) were followed-up for 24 months. Radiographic and clinical data were collected preoperatively as well as 6, 12, and 24 months after surgery using standard instruments (Lysholm and subjective International Knee Documentation Committee score). RESULTS: Excellent and good results were achieved in 67.5% of patients. Thirty-seven patients (86.0%) reported clinical improvement at 24 months compared to preoperative status. Evaluation of the clinical course following HTO revealed a significant increase in function after 12 (P < .01) and 24 (P < .01), but not at 6 months (P = .336) after surgery. A further increase was found between 12 and 24 months (P = .017); 67.5% of the study population returned to their predisease sports activity level at 24 months after surgery. Except for 1 case of intra-articular fracture, no severe intraoperative complications were found. One case of nonunion that demanded additional surgery was observed. CONCLUSIONS: HTO with an open-wedge technique using the TomoFix implant seems to be a safe and efficient procedure. Our data show that postoperative recovery is long, with a majority of patients not reaching a functional end-point by 6 or 12 months. In many patients, further improvement was found after 12 months, which might be related to a removal of the implant. LEVEL OF EVIDENCE: Level IV, therapeutic case series.


Asunto(s)
Desviación Ósea/cirugía , Placas Óseas , Síndromes Compartimentales/cirugía , Osteoartritis de la Rodilla/cirugía , Osteotomía , Adulto , Desviación Ósea/complicaciones , Síndromes Compartimentales/complicaciones , Femenino , Estudios de Seguimiento , Fracturas no Consolidadas/etiología , Humanos , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/complicaciones , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteotomía/efectos adversos , Dolor Postoperatorio/etiología , Radiografía , Resultado del Tratamiento
9.
Curr Opin Plant Biol ; 41: 89-94, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29107827

RESUMEN

While fast plant movements are spectacular but rare, almost all plants exhibit relatively slow, growth-mediated tropic movements that are key to their survival in the natural world. In this brief review, we discuss recent insights into the molecular mechanisms underlying phototropism, gravitropism, hydrotropism, and autostraightening. Careful molecular genetic and physiological studies have helped confirm the importance of lateral auxin gradients in gravitropic and phototropic responses. However, auxin signaling does not explain all tropisms: recent work has shown that abscisic acid signaling mediates root hydrotropism and has implicated mechanosensing in autostraightening, the organ straightening process recently modeled as a proprioceptive response. The interactions between distinct tropic signaling pathways and other internal and external sensory processes are also now being untangled.


Asunto(s)
Desarrollo de la Planta , Fenómenos Fisiológicos de las Plantas , Plantas/genética , Transducción de Señal , Tropismo , Gravitropismo , Luz , Fototropismo , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/fisiología , Raíces de Plantas/efectos de la radiación , Plantas/efectos de la radiación
10.
Science ; 362(6419): 1144-1148, 2018 12 07.
Artículo en Inglés | MEDLINE | ID: mdl-30523107

RESUMEN

Fluoride ion batteries are potential "next-generation" electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion-conducting electrolytes are known only in the solid state. We report a liquid fluoride ion-conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper-lanthanum trifluoride (Cu@LaF3) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion-mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology.

11.
Aviat Space Environ Med ; 78(6): 618-23, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17571665

RESUMEN

INTRODUCTION: A systematic desensitization program designed to help aircrew who have a phobic anxiety of the Helicopter Underwater Escape Training (HUET) has been developed. CASE PRESENTATION: A student pilot presented with a severe phobic anxiety of the HUET course--a result of a being trapped underwater on a marine survival training course. A treatment team was assembled and concluded his phobia could be treated by a systematic desensitization method. An exposure matrix of graded difficulty of in/underwater escapes was performed over 2 d. The student reported that his confidence increased and anxiety reduced as he became accustomed to being strapped into a seat in the escape trainer while wearing increasingly difficult levels of equipment which increased the difficulty of escape, such as taking away nasal protection and goggles. At the end of Day 1, he was able to jettison the exit door/hatch while inverted underwater with a facemask and dressed in a simple coverall. At the end of Day 2, without nasal protection, inverted underwater, wearing full military equipment, he was able to cross the cabin, jettison the exit door, and successfully escape. DISCUSSION: A systematic desensitization treatment program can be used to successfully treat aircrew for phobia of the helicopter underwater escape trainer.


Asunto(s)
Desensibilización Psicológica/métodos , Ahogamiento Inminente/psicología , Trastornos Fóbicos/terapia , Adulto , Medicina Aeroespacial , Aeronaves , Aviación/educación , Planificación en Desastres , Humanos , Masculino , Personal Militar , Medicina Naval , Trastornos Fóbicos/psicología
12.
Aerosp Med Hum Perform ; 88(4): 413-417, 2017 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-28518005

RESUMEN

BACKGROUND: Around 25% of people involved in a helicopter accident in water do not survive. From time to time, physicians and their medical staff are required to fly over water in a helicopter to attend one or more seriously ill patients. Many will have had little or no experience of the issues involved if the helicopter has an accident in the water. Also as Family Practitioners, Aeromedical Examiners, and Flight Surgeons, they are asked to provide advice to patients, travel agents, and airline booking agents about whether an overwater helicopter flight is advisable or not. METHOD: From 50 yr of helicopter accident evidence in the scientific literature, government agency reports, and statistics from the military safety centers and the offshore oil industry, the critical hazards involved and risks to medical staff and their patients have been identified. RESULTS: Patients most at risk are those who suffer from cardiovascular or respiratory disease, have physical disabilities, have a very large body size, and anyone who is a non-swimmer. Medical staff are at risk if they are not familiar with the procedure for escape from a flooded inverted cabin and difficulties after escape from the fuselage with life jackets, life rafts, and sometimes the necessity to swim ashore. CONCLUSIONS: With 50 yr of hindsight, many of the deaths were preventable, and many lives can be saved if a series of very simple mental and physical preventive actions are taken by anyone stepping on to a helicopter that flies over water.Brooks CJ, MacDonald CV. Safety considerations for medical staff and patients who fly over water in a helicopter for work or recreation. Aerosp Med Hum Perform. 2017; 88(4):413-417.


Asunto(s)
Accidentes de Aviación/estadística & datos numéricos , Aeronaves , Salud Laboral , Seguridad del Paciente , Agua Dulce , Humanos , Cuerpo Médico , Océanos y Mares , Estados Unidos/epidemiología
13.
Comb Chem High Throughput Screen ; 13(4): 318-30, 2010 May.
Artículo en Inglés | MEDLINE | ID: mdl-20156149

RESUMEN

State-of-art water gas shift catalysts (FeCr for high temperature shift and CuZn for low temperature shift) are not active enough to be used in fuel processors for the production of hydrogen from hydrocarbon fuels for fuel cells. The need for drastically lower catalyst volumes has triggered a search for novel WGS catalysts that are an order of magnitude more active than current systems. Novel catalytic materials for the high, medium and low temperature water gas shift reactions have been discovered by application of combinatorial methodologies. Catalyst libraries were synthesized on 4 inch wafers in 16 x 16 arrays and screened in a high throughput scanning mass spectrometer in the temperature range 200 degrees C to 400 degrees C. More than 200 wafers were screened under various conditions and more than 250,000 experiments were conducted to comprehensively examine catalyst performance for various binary, ternary and higher-order compositions.


Asunto(s)
Técnicas Químicas Combinatorias , Gases/química , Agua/química , Catálisis , Calor , Espectrometría de Masas
14.
ACS Nano ; 3(2): 379-85, 2009 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-19236075

RESUMEN

Carbon filaments can be grown using hydrocarbons with either exothermic or endothermic catalytic decomposition enthalpies. By in situ monitoring the evolution of the reaction enthalpy during nanotube synthesis via methane gas, we found that although the decomposition reaction of methane is endothermic an exothermic process is superimposed which accompanies the nanotube growth. Analysis shows that the main contributor in this liberated heat is the radiative heat transfer from the surroundings, along with dehydrogenation reaction of in situ formed secondary hydrocarbons on the catalyst surface and the carbon hydrogenation/oxidation processes. This finding implies that nanotube growth process enthalpy is exothermic, and particularly, it extends the commonly accepted temperature gradient driven growth mechanism to the growth via hydrocarbons with endothermic decomposition enthalpy.

15.
Plast Reconstr Surg ; 122(2): 329-339, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18626347

RESUMEN

BACKGROUND: This study reports on the longitudinal experience and outcomes of one surgeon performing free transverse rectus abdominis musculocutaneous (TRAM) flaps on 500 consecutive patients between 1992 and 2003. METHODS: A retrospective review of hospital and outpatient records was performed. Specific risk factors for successful reconstruction were reviewed, including American Society of Anesthesiologists class, obesity, smoking, medical comorbidities, and irradiation and chemotherapy history. Outcomes measured included the length of hospital stay and the incidence of complications including both thrombotic and nonthrombotic complications. RESULTS: Five hundred sixty-nine free TRAM breast reconstructions were performed in a total of 500 patients. Preoperative patient risk factors included obesity, smoking, hypertension, diabetes, and cardiac disease, with three-fourths of the patients being American Society of Anesthesiologists class II or III. Intraoperative or postoperative thrombosis occurred in 35 reconstructions (6.2 percent). Only one patient had a total flap loss, for a flap success rate of 99.7 percent. Significant nonthrombotic complications occurred in 67 patients (13.4 percent). The most common nonthrombotic complications included wound infection (3 percent), fat necrosis (3 percent), and delayed healing (3 percent). Revision procedures after free TRAM reconstruction were performed in 14.4 percent of cases. CONCLUSIONS: The free TRAM flap is a highly reliable method of autogenous breast reconstruction in a broad spectrum of patients. This free flap has a very low thrombotic complication rate, and abdominal donor defect problems have been limited. Finally, this method of reconstruction can be reliably offered to a wide group of patients, including those considered at high risk for a pedicled TRAM flap reconstruction.


Asunto(s)
Neoplasias de la Mama/cirugía , Mamoplastia/métodos , Complicaciones Posoperatorias/etiología , Colgajos Quirúrgicos/irrigación sanguínea , Adulto , Anciano , Femenino , Humanos , Microcirugia/métodos , Persona de Mediana Edad , Grupo de Atención al Paciente , Cuidados Posoperatorios , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/cirugía , Reoperación , Estudios Retrospectivos , Factores de Riesgo , Recolección de Tejidos y Órganos/métodos , Ultrasonografía Doppler
16.
Nephrol Dial Transplant ; 17(5): 734-44, 2002 May.
Artículo en Inglés | MEDLINE | ID: mdl-11981057

RESUMEN

BACKGROUND: Chemokines produced by resident renal cells promote the infiltration of leukocyte subsets. We have analysed the chemotactic responses of CD3+ peripheral blood lymphocytes (PBLs) to factors secreted by proximal tubular epithelial cells (PTEC), assessing the role of chemokines and chemokine receptors in this process. METHODS: By FACS we analysed expression of the chemokine receptors CCR5, CXCR3, CX3CR1, CCR2, CXCR1 and CXCR2 on both freshly isolated and activated PBLs. Using Boyden chambers we studied the chemotactic activity of supernatant from resting and cytokine-stimulated (TNF-alpha and IFN-gamma) PTEC towards PBLs. Soluble recombinant chemokines and blocking antibodies were used to study the role of individual chemokine receptors. Chemokine secretion by PTEC was analysed by ELISA. RESULTS: Only a small proportion of freshly isolated cells expressed the chemokine receptors and there was low grade chemotaxis of these cells towards cytokine-stimulated PTEC supernatant compared with unstimulated PTEC supernatant. After activation, 84% of PBLs expressed CCR5, 90% expressed CXCR3 and 19% expressed CX3CR1. There remained low expression levels of CXCR1, CXCR2 and CCR2. Activated PBLs showed strong chemotactic responses to supernatant from cytokine-stimulated PTEC compared with unstimulated PTEC (P<0.001). Chemotaxis of these cells was inhibited by blocking CCR5, CXCR3 and CX3CR1 by 69%, 71% and 29% respectively, with complete inhibition following combined blockade. ELISA showed high levels of the chemokine RANTES/CCL5 (for CCR5) and IP-10/CXCL10 (for CXCR3) in cytokine-stimulated PTEC supernatant. CONCLUSIONS: Chemokines produced by cytokine activated PTEC promote the selective recruitment of activated T cells via the receptors, CCR5, CXCR3 and CX3CR1. These receptors may be amenable to therapeutic manipulation in renal inflammation.


Asunto(s)
Quimiocinas/fisiología , Quimiotaxis de Leucocito/fisiología , Túbulos Renales Proximales/metabolismo , Receptores CCR5/fisiología , Receptores de Quimiocina/metabolismo , Receptores de Quimiocina/fisiología , Linfocitos T/fisiología , Antígenos de Superficie/metabolismo , Células Sanguíneas/metabolismo , Receptor 1 de Quimiocinas CX3C , Movimiento Celular , Células Cultivadas , Quimiocina CX3CL1 , Quimiocinas CX3C/fisiología , Citocinas/farmacología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Humanos , Túbulos Renales Proximales/citología , Túbulos Renales Proximales/efectos de los fármacos , Linfocitos/fisiología , Proteínas de la Membrana/fisiología , Receptores CXCR3
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