Atmospheric chemistry of CF3CHFCF2OCH3 (HFE-356mec3) and CHF2CHFOCF3 (HFE-236ea1) initiated by OH and Cl and their contribution to global warming.

The kinetic study of the gas-phase reactions of hydroxyl (OH) radicals and chlorine (Cl) atoms with CF3CHFCF2OCH3 (HFE-356mec3) and CHF2CHFOCF3 (HFE-236ea1) was performed by the pulsed laser photolysis/laser-induced fluorescence technique and a relative method by using Fourier Transform infrared (FTIR) spectroscopy as detection technique. The temperature dependences of the OH-rate coefficients (kOH(T) in cm3s-1) between 263 and 353 K are well described by the following expressions: 9.93 × 10-13exp{-(988 ± 35)/T}for HFE-356mec3 and 4.75 × 10-13exp{-(1285 ± 22)/T} for HFE-236ea1. Under NOx-free conditions, the rate coefficients kCl at 298 K and 1013 mbar (760 Torr) of air were determined to be (2.30 ± 1.08) × 10-13 cm3s-1and (1.19 ± 0.10) × 10-15 cm3s-1, for HFE-356mec3 and HFE-236ea1, respectively. Additionally, the relative kinetic study of the Cl + CH2ClCHCl2 reaction was investigated at 298 K, as it was used as a reference reaction in the kinetic study of the Cl-reaction with HFE-356mec3 and discrepant rate coefficients were found in the literature. The global atmospheric lifetimes were estimated relative to CH3CCl3 at the tropospheric mean temperature (272 K) as 1.4 and 8.6 years for HFE-356mec3 and HFE-236ea1, respectively. These values combined with the radiative efficiencies for HFE-356mec3 and HFE-236ea1 derived from the measured IR absorption cross sections (0.27 and 0.41 W m-2 ppv-1) yield global warming potentials at a 100-yrs time horizon of 143 and 1473, respectively. The contribution of HFE-356mec3 and HFE-236ea1 to global warming of the atmosphere would be large if they become widespread increasing their atmospheric concentration.

Spectroscopic study on volasertib: Highly stable complexes with albumin and encapsulation into alginate/montmorillonite bionanocomposites.

In the present work, we study different physicochemical properties related to LADME processes of volasertib, a Polo-like kinase 1 inhibitor in advanced clinical trials. Firstly, the protonation equilibria, the extent of ionization at the physiological pH and pKa values of this drug are studied combining spectroscopic techniques and computational calculations. Secondly, the binding process of volasertib to the human serum albumin (HSA) protein is analyzed by fluorescence spectroscopy. We report a high binding constant to HSA (Ka = 4.10 × 106 M-1) and their pharmacokinetic implications are discussed accordingly. The negative enthalpy and entropy (ΔH0 = -54.49 kJ/mol; ΔS0 = -58.90 J K-1 mol-1) determined for the binding process suggests the implication of hydrogen bonds and van der Waals interactions in the formation of the HSA-volasertib complex. Additionally, volasertib is encapsulated in an alginate/montmorillonite bionanocomposite as a proof of concept for an oral delivery nanocarrier. The physical properties of that nanocomposite as well as volasertib delivery kinetics are analyzed.

Ventilatory Pattern Influences Tolerance to Normobaric Hypoxia in Healthy Adults.

INTRODUCTION: Tolerance to breathing in conditions with a decreased oxygen ratio is subject-specific. A normobaric hypoxia tolerance test (NHTT) is performed to assess the ability of each individual, as this may be influenced by genetic or personal factors such as age or gender. The aim of this study is to test the influence of deep breathing on hypoxia tolerance time. MATERIAL AND METHODS: A total of 45 subjects (21 parachutists and 24 students) performed two NHTTs at 5050 m altitude (iAltitude). Arterial (SatO2) and muscle (SmO2) oxygen saturation were monitored with the Humon Hex® device. The first NHTT was performed with free breathing, without any instructions; and the second NHTT was performed with wide, slow, diaphragmatic breathing. The NHTT was terminated at the end of 10 min or when a value of less than 83% was obtained. RESULTS: The first NHTT was completed by 38.1% of parachutist and 33.3% of students while the second NHTT was completed by 85.7% and 75%, respectively. In the second NHTT, both parachutists and students had a significantly (p = 0.001) longer duration compared to the first NHTT. SmO2 and SatO2 values also increased significantly (p < 0.001) in both groups (p < 0.05). CONCLUSION: Performing controlled diaphragmatic breathing is successful in increasing hypoxia tolerance time and/or SatO2 values.

Unusually High Affinity of the PLK Inhibitors RO3280 and GSK461364 to HSA and Its Possible Pharmacokinetic Implications.

The binding processes of two Polo-like kinase inhibitors, RO3280 and GSK461364, to the human serum albumin (HSA) protein as well as the protonation equilibria of both compounds have been studied combining absorbance and fluorescence spectroscopy experiments together with density functional theory calculations. We found that the charge states of RO3280 and GSK461364 are +2 and +1, respectively, at the physiological pH. Nevertheless, RO3280 binds to HSA in the charge state +1 prior to a deprotonation pre-equilibrium. Binding constants to site I of HSA of 2.23 × 106 and 8.80 × 104 M-1 were determined for RO3280 and GSK461364, respectively, at 310 K. The binding processes of RO3280 and GSK461364 to HSA are entropy- and enthalpy-driven, respectively. The positive enthalpy found for the RO3280-HSA complex formation could be related to a proton pre-equilibrium of RO3280.

Opinions of nurses regarding Euthanasia and Medically Assisted Suicide.

BACKGROUND: Safeguarding the right to die according to the principles of autonomy and freedom of each person has become more important in the last decade, therefore increasing regulation of Euthanasia and Medically Assisted Suicide (MAS). AIMS: To learn the opinions that the nurses of the autonomous region of Madrid have regarding Euthanasia and Medically Assisted Suicide. RESEARCH DESIGN: Cross-sectional descriptive study. PARTICIPANTS AND RESEARCH CONTEXT: All registered nurses in Madrid. The study was done by means of a self-completed anonymous questionnaire. The variables studied were social-demographic, giving opinions about Euthanasia and MAS. ETHICAL CONSIDERATIONS: Each participant was assured maximum confidentiality and anonymity, ensuring the ethical principles set out in the Declaration of Helsinki, as well as in the Organic Law 3/2018, on Personal Data Protection and guarantee of digital rights. FINDINGS: A total of 489 nurses answered the questionnaire. In total, 75.7% of the nurses confirmed that Euthanasia should be regulated in Spain. 66.3% indicated that information on Euthanasia should be provided jointly by doctors and nurses, and 42.3% considered that it could be applied by both medical and nursing professionals. A total of 87.2% advocated the participation of nurses in health policy, influencing the drafting of the law. In the face of possible regulation, 35% would request Conscientious Objection, being closely related to their religious beliefs. DISCUSSION: Different authors point out that nurses' perceptions and attitudes towards Euthanasia are conditioned by different factors, such as religion, gender, poor palliative care, legality and the patient's right to die. CONCLUSION: Nurses are positioned in favour of the regulation and practice of Euthanasia and MAS, depending on their age, years of experience, training, model of care and especially religious beliefs.

Kinetics of CF3CH2OCH3 (HFE-263fb2), CHF2CF2CH2OCH3 (HFE-374pcf), and CF3CF2CH2OCH3 (HFE-365mcf3) with OH radicals, IR absorption cross sections, and global warming potentials.

Hydrofluoroethers (HFEs), such as CF3CH2OCH3 (HFE-263fb2), CHF2CF2CH2OCH3 (HFE-374pcf), and CF3CF2CH2OCH3 (HFE-365mcf3), have been proposed in the last few decades as the third-generation replacements for perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs) because of their zero stratospheric ozone depletion potentials and relatively low global warming potentials (GWPs). These GWPs depend on the radiative efficiency (RE) and the atmospheric lifetime (τOH) of HFEs due to the reaction with hydroxyl (OH) radicals. The temperature and pressure dependencies of the OH-rate coefficient (kOH(T)) for HFE-263fb2, HFE-374pcf, and HFE-365mcf3 are not known. Therefore, in this paper, we present the first study on the temperature (263-353 K) and pressure (50-500 torr of helium) dependence of kOH(T) for the titled HFEs. No pressure dependence of kOH(T) was observed in the investigated range. From kOH(298 K), estimated τOH are 17 days (for HFE-263fb2), 12 days (for HFE-374pcf), and 13 days (for HFE-365mcf3). The observed T-dependencies of kOH(T) (in cm3 molecule-1 s-1) are well described by (3.88 ± 0.89) × 10-12 exp[-(508 ± 69)/T] for HFE-263fb2, (2.81 ± 0.33) × 10-12 exp[-(312 ± 35)/T] for HFE-374pcf, and (2.60 ± 0.31) × 10-12 exp[-(319 ± 35)/T] for HFE-365mcf3. A correlation between log kOH(298 K) and the activation energy (Ea) of the process is presented, allowing the prediction of Ea for OH-reactions with other HFEs, exclusively investigated at room temperature. In addition to the kinetic measurements, the infrared absorption cross sections of HFE-263fb2, HFE-374pcf, and HFE-365mcf3 were determined between 520 and 3100 cm-1. Lifetime corrected REs and GWPs relative to CO2 at 100 years' time horizon were reexamined. The impact of the investigated HFEs on the radiative forcing of climate change would be negligible.

Shedding light on the binding mechanism of kinase inhibitors BI-2536, Volasetib and Ro-3280 with their pharmacological target PLK1.

In the present work, the interactions of the novel kinase inhibitors BI-2536, Volasetib (BI-6727) and Ro-3280 with the pharmacological target PLK1 have been studied by fluorescence spectroscopy and molecular dynamics calculations. High Stern-Volmer constants were found in fluorescence experiments suggesting the formation of stable protein-ligand complexes. In addition, it was observed that the binding constant between BI-2536 and PLK1 increases about 100-fold in presence of the phosphopeptide Cdc25C-p that docks to the polo box domain of the protein and releases the kinase domain. All the determined binding constants are higher for the kinase inhibitors than for their competitor for the active center (ATP) being BI-2536 and Volasertib the inhibitors that showed more affinity for PLK1. Calculated binding free energies confirmed the higher affinity of PLK1 for BI-2536 and Volasertib than for ATP. The higher affinity of the inhibitors to PLK1 compared to ATP was mainly attributed to stronger van der Waals interactions. Results may help with the challenge of designing and developing new kinase inhibitors more effective in clinical cancer therapy.

Novel Fluorescence Guanidine Molecules for Selective Sulfate Anion Detection in Water Complex Samples over a Wide pH Range.

Quantitative analysis of sulfate anions in water still remains an important challenge for the society. Among all the methodologies, the most successful one is based on optical supramolecular receptors because the presence of small concentrations of sulfate anion modifies the photophysical properties of the receptor. In this case, fluorescence anion sensors have been designed by the incorporation of guanidine motifs into fluorenyl cores. The photophysical behaviors of the new mono- (M) and bis-guanidine (B) derivatives were studied through pH dependence, solvent effects, and ion sensing on steady-state spectra and time-resolved fluorescence spectroscopy. In more detail, the results demonstrate that M is a highly selective and sensitive sulfate ion receptor in real water samples and, even more importantly, its function remains unchanged at different ranges of pH. The reason behind this resides on the fluorescence quenching produced by an internal charge-transfer process when the sulfate anion is complexed with M. It is worth noting that the global and partial affinity constants (1010 M-2 and 105 M-1, respectively) of complex formation are far above from the current sulfate sensors in water (104 M-1) which give an LOD of 0.10 µM in water with an analytical range of 2.5-10 µM. On the other hand, although it would seem, at first sight, that the B derivate will be the most promising one, the possibility of having two simultaneous protonation states reduces the complex formation and, therefore, its sensitivity to sulfate anions. The results presented here offer the possibility of using a new molecule in water environments, which opens the door to infinite applications such as the detection of trace amounts of sulfate ions in food or water.

Gas-Phase Reaction of trans-2-Methyl-2-butenal with Cl: Kinetics, Gaseous Products, and SOA Formation.

The gas-phase reaction between trans-2-methyl-2-butenal and chlorine (Cl) atoms has been studied in a simulation chamber at 298 ± 2 K and 760 ± 5 Torr of air under free-NOx conditions. The rate coefficient of this reaction was determined as k = (2.45 ± 0.32) × 10-10 cm3 molecule-1 s-1 by using a relative method and Fourier transform infrared spectroscopy. In addition to this technique, gas chromatography coupled to mass spectrometry and proton transfer time-of-flight mass spectrometry were used to detect and monitor the time evolution of the gas-phase reaction products. The major primary reaction product from the addition of Cl to the C-3 of trans-2-methyl-2-butenal was 3-chloro-2-butanone, with a molar yield (YProd) of (52.5 ± 7.3)%. Acetaldehyde (Y = (40.8 ± 0.6)%) and HCl were also identified, indicating that the H-abstraction by Cl from the aldehyde group is a reaction pathway as well. Secondary organic aerosol (SOA) formation was investigated by using a fast mobility particle sizer spectrometer. The SOA yield in the Cl + trans-2-methyl-2-butenal reaction is reported to be lower than 2.4%, thus its impact can be considered negligible. The atmospheric importance of the titled reaction is similar to the corresponding OH reaction in areas with high Cl concentration.

Gas-phase kinetics of CH3CHO with OH radicals between 11.7 and 177.5 K.

Gas-phase reactions in the interstellar medium (ISM) are a source of molecules in this environment. The knowledge of the rate coefficient for neutral-neutral reactions as a function of temperature, k(T), is essential to improve astrochemical models. In this work, we have experimentally measured k(T) for the reaction between the OH radical and acetaldehyde, both present in many sources of the ISM. Laser techniques coupled to a CRESU system were used to perform the kinetic measurements. The obtained modified Arrhenius equation is k(T = 11.7-177.5 K) = (1.2 ± 0.2) × 10-11 (T/300 K)-(1.8±0.1) exp-{(28.7 ± 2.5)/T} cm3 molecule-1 s-1. The k(T) value of the title reaction has been measured for the first time below 60 K. No pressure dependence of k(T) was observed at ca. 21, 50, 64 and 106 K. Finally, a pure gas-phase model indicates that the title reaction could become the main CH3CO formation pathway in dark molecular clouds, assuming that CH3CO is the main reaction product at 10 K.

Functionalized CdSe/ZnS Quantum Dots for Intracellular pH Measurements by Fluorescence Lifetime Imaging Microscopy.

pH is an important biomarker for many human diseases and great efforts are being made to develop new pH probes for bioimaging and biomedical applications. Here, the use of three different CdSe/ZnS QDs, functionalized with d-penicillamine and small peptides, as pH probes for fluorescence lifetime imaging microscopy (FLIM) is investigated. The fluorescence pH sensitivity of the nanoparticles is analyzed in different experimental media: aqueous solution, synthetic intracellular medium, and mesenchymal C3H10T1/2 and tumoral SK-MEL-2 cell lines. Different experiments along with theoretical calculations are conducted to unravel the mechanisms causing pH sensitivity of the nanoparticles and the effect of the length and composition of the peripheral branches on their photophysical properties. Absolute intracellular pH values measured in live cells with FLIM using a fluorescent probe based on a QD are reported here for the first time (intracellular pH values of 7.0 and 7.1 for C3H10T1/2 and SK-MEL-2 cells, respectively). These fluorescent nanoprobes can also be used to distinguish between different types of cells in cocultures on the basis of their different fluorescence lifetimes in dissimilar intracellular environments.

The role of water and influence of hydrogen bonding on the self-assembly aggregation induced emission of an anthracene-guanidine-derivative.

We report a luminescent anthracene-guanidine derivative that forms rare T-shape dimers, resulting in an excimer with a quantum yield approaching one. Water plays a fundamental role through H-bonding guiding the self-assembly. These results establish a new framework for environmentally friendly aggregation-induced emission luminogens.

Estrés cardiaco asociado a la realización de una formación acrobática paracaidista / Cardiac stress associated to the realization of an acrobatic skydiver formation

INTRODUCCIÓN: El paracaidismo acrobático es una actividad de alto riesgo. Este riesgo y la dificultad de las maniobras son factores estresantes que modifican la respuesta cardiaca. Nuestro objetivo es analizar el trazado electrocardiográfico y la evolución de la frecuencia cardiaca (FC) durante esta actividad paracaidista creando una figura de alta dificultad. MÉTODO: Colocamos un monitor electrocardiográfico Nuubo a dos paracaidistas experimentados de la Patrulla Acrobática Paracaidista del Ejército del Aire (PAPEA) durante la ejecución de una formación acrobática en la que cuatro paracaidistas se unen durante el vuelo creando una figura denominada "diamante". Analizamos el electrocardiograma (ECG) durante todo el ejercicio y recogimos la FC en las siguientes fases: 1.- Subiendo al avión; 2.- Despegando; 3.- Antes de saltar; 4.- Preparando la figura; 5.- En formación y 6.- Tomando tierra. Se repitió cinco veces, obteniéndose la media de cada saltador. Previamente se realizó un ECG en reposo y una prueba de esfuerzo máxima (PE) en tapiz rodante. RESULTADOS: Ambos saltadores consiguen la mayor FC mientras vuelan preparando la formación (165 y 143 lat/min), supone el 87% y 77% de la FC máxima alcanzada en la PE. No se recogen FC inferiores a 95 pulsaciones en ninguna fase ni salto. Cada saltador tiene un tipo de respuesta, según le afecte el momento del despegue. En uno la FC aumenta paulatinamente hasta ella llega al pico máximo cuando están en formación y en el otro aparece otro pico, que se repite en los cinco saltos, coincidiendo con el despegue. En el ECG sólo se han observado episodios continuados de taquicardias sinusales. CONCLUSIONES: Concluimos que el estrés cardiaco producido por la realización de este tipo de ejercicios se manifiesta por aumentos importantes de la frecuencia cardiaca, en torno al 80% de la frecuencia cardiaca máxima, sin otras alteraciones electrocardiográficas

INTRODUCTION: Acrobatic skydiving is considered a high risk activity. This risk and the difficulty of the maneuvers are stressors that modify the cardiac activity. Our aim is to analyze the electrocardiographic tracing and the evolution of the heart rate during this paratrooper activity, creating a figure of high difficulty. METHOD: We put a Nuubo electrocardiographic monitor on two experienced paratroopers members of the Acrobatic Patrooper Patrol of the Air Force (PAPEA) during the execution of an acrobatic exercise, called "diamond", in which four parachutists are attached during the flight. We analyzed the electrocardiogram (ECG) during the whole activity and we got the heart rate (HR) in the following phases: 1.- Up to the aircraft; 2.-Taking off; 3.- Before jumping; 4.- Preparing the figure; 5.- Formation flight and 6.- Landing. They jumped five times, obtaining the average of each jumper. Previously we made them an ECG at rest and maximal treadmill stress test (ST ).RESULTS: Both jumpers get the largest HR while they fly preparing the formation (165 and 143 beats/min), it is 87% and 77% of the max HR reached in ST. Beats under 95 b/min are not registered in any stage or jump. Each jumper has a different response, depending on the effect that the take-off has on him. In one of them, HR increases gradually until it reaches the maximum peak when they are in formation, and on the other jumper it appears another peak, that is repeated in the five jumps, coinciding with the taking off. There is no other ECG alterations. CONCLUSIONS: We conclude that cardiac stress caused by carrying out this type of exercises is manifested by significant increases in heart rate, around 80% of the maximum heart rate, without other electrocardiographic abnormalities

Experimental and theoretical investigation on the OH + CH3C(O)CH3 reaction at interstellar temperatures (T=11.7-64.4 K).

The rate coefficient, k(T), for the gas-phase reaction between OH radicals and acetone CH3C(O)CH3, has been measured using the pulsed CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) technique (T = 11.7-64.4 K). The temperature dependence of k(T = 10-300 K) has also been computed using a RRKM-Master equation analysis after partial revision of the potential energy surface. In agreement with previous studies we found that the reaction proceeds via initial formation of two pre-reactive complexes both leading to H2O + CH3C(O)CH2 by H-abstraction tunneling. The experimental k(T) was found to increase as temperature was lowered. The measured values have been found to be several orders of magnitude higher than k(300 K). This trend is reproduced by calculations, with a special good agreement with experiments below 25 K. The effect of total gas density on k(T) has been explored. Experimentally, no pressure dependence of k(20 K) and k(64 K) was observed, while k(50 K) at the largest gas density 4.47×1017 cm-3 is twice higher than the average values found at lower densities. The computed k(T) is also reported for 103 cm-3 of He (representative of the interstellar medium). The predicted rate coefficients at 10 K surround the experimental value which appears to be very close to the low pressure regime prevailing in the interstellar medium. For gas-phase model chemistry of interstellar molecular clouds, we suggest using the calculated value of 1.8×10-10 cm3 molecule-1 s-1 at 10 K and the reaction products are water and CH3C(O)CH2 radicals.

Gas-phase reactivity of CH3OH toward OH at interstellar temperatures (11.7-177.5 K): experimental and theoretical study.

The reactivity of methanol (CH3OH) toward the hydroxyl (OH) radical was investigated in the temperature range 11.7-177.5 K using the CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) technique. In the present study, the temperature dependence of the rate coefficient for the OH + CH3OH reaction, k(T), has been revisited and additional experimental and computational data are reported. New kinetic measurements were performed to fill the existing gaps (<22 K, 22-42 K and 88-123 K), reporting k(T < 20 K) for the first time. The lowest temperature ever achieved by a pulsed CRESU has been obtained in this work (11.7 K). k(T) abruptly increases by almost 2 orders of magnitude from 177.5 K to around 100 K. At T < 100 K, this increase is less pronounced, reaching the capture limit at temperatures below 22 K. The pressure dependence of k(T) has been investigated for selected temperatures and gas densities (1.5 × 1016 to 4.3 × 1017 cm-3), combining our results with those previously reported. No dependence was observed within the experimental uncertainties below 110 K. The high- and low-pressure rate coefficients, kHPL(T) and kLPL(T), were also studied in detail using high-level quantum chemical and theoretical kinetic methodologies, closely reproducing the experimental data between 20 and 400 K. The results suggest that the experimental data are near the high pressure limit at the lowest temperatures, but that the reaction remains a fast and effective source of CH2OH and CH3O at the low pressures and temperatures prevalent in the interstellar medium.

Assessment of doxorubicin delivery devices based on tailored bare polycaprolactone against glioblastoma.

Bare polycaprolactones with controlled molar mass and dispersity were employed to manufacture biodegradable devices, which were applied for doxorubicin delivery in glioblastoma. Micro- and nanoscale devices were prepared by emulsion formation or by a combination of precipitation and hydrolysis. The carriers were characterized by scanning electron microscopy, dynamic light scattering techniques, thermogravimetric analysis and differential scanning calorimetry. The encapsulation parameters and drug-release profiles are discussed in order to evaluate the influence of different fundamental parameters, such as molar mass and dispersity value, pH, morphology or crystallinity, on the efficiency of the doxorubicin delivery systems. The ability of doxorubicin-loaded micro- and nanoscale devices to induce cellular toxicity in glioblastoma cells was also explored. A cell viability assay against C6 cells of doxorubicin-loaded nanocarriers showed higher cytotoxicity than doxorubicin-loaded microcarriers. In addition, doxorubicin-loaded nanocarriers also showed good antitumor profile in human tumoral cells and improved the security profile in relation to free doxorubicin in non-tumoral cells. Consistent with the assessment study described in this manuscript, the results provide a proof of concept for the suitability of the approach, based on bare polycaprolactone, to local controlled-sustained release of doxorubicin for the treatment of glioblastoma.

Fuerza isocinética y test de salto vertical en paracaidistas acrobáticos / Isokinetic strength and vertical jump test in acrobatic skydivers

Introducción: Las rodillas de los paracaidistas pueden sufrir lesiones durante la toma de tierra que se pueden prevenir con una adecuada fuerza muscular. Esta fuerza se puede evaluar de manera directa con dinamómetros isocinéticos y con métodos indirectos mediante el test de salto vertical. Objetivo: El objetivo del estudio fue determinar y analizar, en paracaidistas profesionales, las relaciones entre los valores fuerza isocinética máxima de cuádriceps e isquiosurales con la altura y el tiempo de vuelo en saltos verticales. Material y método: Valoramos a los catorce paracaidistas pertenecientes a la Patrulla Acrobática Paracaidista del Ejército del Aire mediante un dinamómetro isocinético (a 60º/s y 180º/s) tanto para el trabajo concéntrico como excéntrico, obteniéndose los picos máximos de fuerza y las ratios isquiosurales/cuádriceps. Evaluamos, sobre una plataforma de contacto, los siguientes saltos verticales: Squat Jump, Counter Movement Jump y Abalakov Jump. Resultados: Los resultados indican que los picos de fuerza máxima de la musculatura flexo-extensora de la rodilla son mayores en modalidad excéntrica, y en el equipo masculino. Las ratios isquiosurales/cuádriceps muestran un predominio de los primeros. Abalakov Jump es el salto donde mayor altura y tiempo de vuelo se consigue. Existe una correlación positiva entre el tiempo de vuelo de todos los saltos y la fuerza concéntrica del cuádriceps. La altura de salto por el peso corporal (Trabajo = Kg x m) se correlaciona con los picos de fuerza concéntrica y excéntrica del cuádriceps. La relación es mayor en la velocidad más alta. La fuerza excéntrica de isquiosurales no se correlaciona con la altura de vuelo, pero sí la fuerza concéntrica. Conclusiones: Podemos concluir que las rodillas de los paracaidistas presentan un predominio en la fuerza de los isquiosurales, lo que se considera positivo para la actividad que realizan ya que contribuye a mejorar la estabilidad de la rodilla y que hay altas correlaciones entre los picos de fuerza isocinético y el trabajo realizado en los saltos verticales

Introduction: Knees of the parachutists can suffer injuries during the landing that can be avoided with a correct muscular strength. This strength is posible to be evaluated of direct way with isokinetic dynanometers and indirect methods using the test of vertical jump. Objective: The aim of this study was to determine and analyze, in professional skydivers, the relationship between the values of isokinetic force of quadriceps and hamstrings with height and time of flight in vertical jumps. Material and methods: We studied the fourteen paratroopers belonging to the (patrol acrobatic jumper of the air force) using an isokinetic dynamometer (60°/s and 180°/s) both for concentric work as eccentric, obtaining the peaks maximum of strength and hamstrings/quadriceps ratios. Evaluate, on a platform of contact, the following vertical jumps: Abalakov Jump and Squat Jump, Counter Movement Jump. Results: The results indicate that the peaks of maximum strength of flexor and extensor muscles of the knee are greater in eccentric mode, and the men’s team. Hamstrings/quadriceps ratios show a predominance of the first. AJ is the jump where greater height and time of flight is achieved. There is a positive correlation between the flight time of all jumps and concentric quadriceps strength. The height of jump by body weight (Work = Kg x m) correlates with the peaks of concentric and eccentric strength of the quadriceps. The ratio is higher in the higher speed. The eccentric strength of hamstrings does not correlate with the height of flight, but the concentric strength. Conclusions: We can conclude that the knees of the skydivers have a predominance of the hamstrings what is considered positive for the activity carried out, since it helps to improve the stability of the knee and that there are high correlations between the peaks of force isokinetic and the work done in the jumps vertical