Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 107
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Proc Natl Acad Sci U S A ; 121(30): e2406993121, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39018189

RESUMEN

Humans update their social behavior in response to past experiences and changing environments. Behavioral decisions are further complicated by uncertainty in the outcome of social interactions. Faced with uncertainty, some individuals exhibit risk aversion while others seek risk. Attitudes toward risk may depend on socioeconomic status; and individuals may update their risk preferences over time, which will feedback on their social behavior. Here, we study how uncertainty and risk preferences shape the evolution of social behaviors. We extend the game-theoretic framework for behavioral evolution to incorporate uncertainty about payoffs and variation in how individuals respond to this uncertainty. We find that different attitudes toward risk can substantially alter behavior and long-term outcomes, as individuals seek to optimize their rewards from social interactions. In a standard setting without risk, for example, defection always overtakes a well-mixed population engaged in the classic Prisoner's Dilemma, whereas risk aversion can reverse the direction of evolution, promoting cooperation over defection. When individuals update their risk preferences along with their strategic behaviors, a population can oscillate between periods dominated by risk-averse cooperators and periods of risk-seeking defectors. Our analysis provides a systematic account of how risk preferences modulate, and even coevolve with, behavior in an uncertain social world.


Asunto(s)
Teoría del Juego , Conducta Social , Humanos , Incertidumbre , Asunción de Riesgos , Dilema del Prisionero , Conducta Cooperativa
2.
Proc Natl Acad Sci U S A ; 120(12): e2216218120, 2023 03 21.
Artículo en Inglés | MEDLINE | ID: mdl-36927152

RESUMEN

The concept of fitness is central to evolution, but it quantifies only the expected number of offspring an individual will produce. The actual number of offspring is also subject to demographic stochasticity-that is, randomness associated with birth and death processes. In nature, individuals who are more fecund tend to have greater variance in their offspring number. Here, we develop a model for the evolution of two types competing in a population of nonconstant size. The fitness of each type is determined by pairwise interactions in a prisoner's dilemma game, and the variance in offspring number depends upon its mean. Although defectors are preferred by natural selection in classical population models, since they always have greater fitness than cooperators, we show that sufficiently large offspring variance can reverse the direction of evolution and favor cooperation. Large offspring variance produces qualitatively new dynamics for other types of social interactions, as well, which cannot arise in populations with a fixed size or with a Poisson offspring distribution.


Asunto(s)
Conducta Cooperativa , Teoría del Juego , Humanos , Dinámica Poblacional , Densidad de Población , Selección Genética
3.
Glob Chang Biol ; 30(1): e17153, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38273531

RESUMEN

Soils store large quantities of carbon in the subsoil (below 0.2 m depth) that is generally old and believed to be stabilized over centuries to millennia, which suggests that subsoil carbon sequestration (CS) can be used as a strategy for climate change mitigation. In this article, we review the main biophysical processes that contribute to carbon storage in subsoil and the main mathematical models used to represent these processes. Our guiding objective is to review whether a process understanding of soil carbon movement in the vertical profile can help us to assess carbon storage and persistence at timescales relevant for climate change mitigation. Bioturbation, liquid phase transport, belowground carbon inputs, mineral association, and microbial activity are the main processes contributing to the formation of soil carbon profiles, and these processes are represented in models using the diffusion-advection-reaction paradigm. Based on simulation examples and measurements from carbon and radiocarbon profiles across biomes, we found that advective and diffusive transport may only play a secondary role in the formation of soil carbon profiles. The difference between vertical root inputs and decomposition seems to play a primary role in determining the shape of carbon change with depth. Using the transit time of carbon to assess the timescales of carbon storage of new inputs, we show that only small quantities of new carbon inputs travel through the profile and can be stabilized for time horizons longer than 50 years, implying that activities that promote CS in the subsoil must take into consideration the very small quantities that can be stabilized in the long term.


Asunto(s)
Secuestro de Carbono , Carbono , Cambio Climático , Suelo , Ecosistema
4.
Ecotoxicol Environ Saf ; 280: 116540, 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-38833982

RESUMEN

The widespread utilization of polyethylene terephthalate (PET) has caused a variety of environmental and health problems. Compared with traditional thermomechanical or chemical PET cycling, the biodegradation of PET may offer a more feasible solution. Though the PETase from Ideonalla sakaiensis (IsPETase) displays interesting PET degrading performance under mild conditions; the relatively low thermal stability of IsPETase limits its practical application. In this study, enzyme-catalysed PET degradation was investigated with the promising IsPETase mutant HotPETase (HP). On this basis, a carbohydrate-binding module from Bacillus anthracis (BaCBM) was fused to the C-terminus of HP to construct the PETase mutant (HLCB) for increased PET degradation. Furthermore, to effectively improve PET accessibility and PET-degrading activity, the truncated outer membrane hybrid protein (FadL) was used to expose PETase and BaCBM on the surface of E. coli (BL21with) to develop regenerable whole-cell biocatalysts (D-HLCB). Results showed that, among the tested small-molecular weight ester compounds (p-nitrophenyl phosphate (pNPP), p-Nitrophenyl acetate (pNPA), 4-Nitrophenyl butyrate (pNPB)), PETase displayed the highest hydrolysing activity against pNPP. HP displayed the highest catalytic activity (1.94 µM(p-NP)/min) at 50 °C and increased longevity at 40 °C. The fused BaCBM could clearly improve the catalytic performance of PETase by increasing the optimal reaction temperature and improving the thermostability. When HLCB was used for PET degradation, the yield of monomeric products (255.7 µM) was ∼25.5 % greater than that obtained after 50 h of HP-catalysed PET degradation. Moreover, the highest yield of monomeric products from the D-HLCB-mediated system reached 1.03 mM. The whole-cell catalyst D-HLCB displayed good reusability and stability and could maintain more than 54.6 % of its initial activity for nine cycles. Finally, molecular docking simulations were utilized to investigate the binding mechanism and the reaction mechanism of HLCB, which may provide theoretical evidence to further increase the PET-degrading activities of PETases through rational design. The proposed strategy and developed variants show potential for achieving complete biodegradation of PET under mild conditions.


Asunto(s)
Biodegradación Ambiental , Burkholderiales , Escherichia coli , Tereftalatos Polietilenos , Tereftalatos Polietilenos/química , Tereftalatos Polietilenos/metabolismo , Burkholderiales/enzimología , Escherichia coli/genética , Bacillus anthracis/enzimología , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Ingeniería de Proteínas
5.
J Asian Nat Prod Res ; : 1-6, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38860491

RESUMEN

Three new flavonoids including two isoflavanones sophortones A and B (1 and 2), and one chalcone sophortone C (3) were isolated from the roots of Sophora tonkinensis. Their structures were established by UV, IR, HRESIMS, and NMR data. The absolute configurations of 1 and 2 were determined by electronic circular dichroism (ECD) calculations.

6.
J Nanobiotechnology ; 21(1): 64, 2023 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-36823540

RESUMEN

BACKGROUND: Mild-temperature photothermal therapy (mild PTT) is a safe and promising tumor therapeutic modality by alleviating the damage of healthy tissues around the tumor due to high temperature. However, its therapeutic efficiency is easily restricted by heat shock proteins (HSPs). Thus, exploitation of innovative approaches of inhibiting HSPs to enhance mild PTT efficiency is crucial for the clinical application of PTT. RESULTS: Herein, an innovative strategy is reported: pyroptosis-boosted mild PTT based on a Mn-gallate nanoformulation. The nanoformulation was constructed via the coordination of gallic acid (GA) and Mn2+. It shows an acid-activated degradation and releases the Mn2+ and GA for up-regulation of reactive oxygen species (ROS), mitochondrial dysfunction and pyroptosis, which can result in cellular ATP deprivation via both the inhibiton of ATP generation and incresed ATP efflux. The reduction of ATP and accumulation of ROS provide a powerful approach for inhibiting the expression of HSPs, which enables the nanoformulation-mediated mild PTT. CONCLUSIONS: Our in-vitro and in-vivo results demonstrate that this strategy of pyroptosis-assited PTT can achieve efficient mild PTT efficiency for osteosarcoma therapy.


Asunto(s)
Adenosina Trifosfato , Neoplasias , Terapia Fototérmica , Piroptosis , Humanos , Adenosina Trifosfato/deficiencia , Adenosina Trifosfato/metabolismo , Línea Celular Tumoral , Proteínas de Choque Térmico , Nanopartículas , Neoplasias/metabolismo , Neoplasias/terapia , Terapia Fototérmica/métodos , Piroptosis/fisiología , Especies Reactivas de Oxígeno , Temperatura
7.
Glob Chang Biol ; 28(18): 5587-5599, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-35748530

RESUMEN

Soil carbon (C) is comprised of a continuum of organic compounds with distinct ages (i.e., the time a C atom has experienced in soil since the C atom entered soil). The contribution of different age groups to soil C efflux is critical for understanding soil C stability and persistence, but is poorly understood due to the complexity of soil C pool age structure and potential distinct turnover behaviors of age groups. Here, we build upon the quantification of soil C transit times to infer the age of C atoms in soil C efflux (aefflux ) from seven sequential soil layer depths down to 2 m at a global scale, and compare this age with radiocarbon-inferred ages of C retained in corresponding soil layers (asoil ). In the whole 0-2 m soil profile, the mean aefflux is 194 21 1021 (mean with 5%-95% quantiles) year and is just about one-eighth of asoil ( 1476 717 2547 year), demonstrating that younger C dominates soil C efflux. With increasing soil depth, both aefflux and asoil are increased, but their disparities are markedly narrowed. That is, the proportional contribution of relatively younger soil C to efflux is decreased in deeper layers, demonstrating that C inputs (new and young) stay longer in deeper layers. Across the globe, we find large spatial variability of the contribution of soil C age groups to C efflux. Especially, in deep soil layers of cold regions (e.g., boreal forests and tundra), aefflux may be older than asoil , suggesting that older C dominates C efflux only under a limited range of conditions. These results imply that most C inputs may not contribute to long-term soil C storage, particularly in upper layers that hold the majority of new C inputs.


Asunto(s)
Carbono , Suelo , Carbono/química , Ciclo del Carbono , Compuestos Orgánicos , Suelo/química , Tundra
8.
Sensors (Basel) ; 22(11)2022 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-35684869

RESUMEN

Monitoring the early strength formation process of cement is of great importance for structural construction management and safety. In this study, we investigated the relationship between the eigenfrequency and the early strength development of cement mortar. Embedded piezoceramic-based smart aggregates recorded the early strength of cement mortar. An eigenfrequency analysis model demonstrated the relationship between strength and frequency. Experiments were performed by using piezoelectric transducers to monitor the early strength formation process during the testing period. Three types of specimens with different strength grades were tested, and the early strength formation processes were recorded. The experimental results demonstrate that cement mortar strength has a good linear relationship with the resonance frequency, and the average square of the correlation coefficient is greater than 0.98. The results show that structural health monitoring technology is a feasible method of assessing structural safety conditions and has a broad market in the structural construction industry.


Asunto(s)
Industria de la Construcción , Materiales de Construcción , Fuerza Compresiva , Transductores
9.
J Theor Biol ; 527: 110818, 2021 10 21.
Artículo en Inglés | MEDLINE | ID: mdl-34181968

RESUMEN

In a population of interacting individuals, the environment for interactions often changes due to individuals' behaviors, which in turn drive the evolution of individuals' behaviors. The interplay between the environment and individuals' behaviors has been demonstrated to remarkably influence the evolutionary outcomes. In reality, in highly cognitive species such as social primates and human beings, individuals are often capable of perceiving the environment change and then differentiate their strategies across different environment states. We propose a model of environmental feedback with state-dependent strategies: individuals have perceptions of distinct environment states and therefore take distinct sub-strategies under each of them; based on the sub-strategy, individuals then decide their behaviors; their behaviors subsequently modify the environment state. We use the theory of stochastic games and evolutionary dynamics to analyze this idea. We find that when environment changes slower than behaviors, state-dependent strategies (i.e. taking different sub-strategies under different environment states) can outperform state-independent strategies (i.e. taking an identical sub-strategy under all environment states), such as Win-Stay, Lose-Shift, the most leading strategy among state-independent strategies. The intuition is that delayed environmental feedback provides chances for individuals with state-dependent strategies to exploit those with state-independent strategies. Our results hold (1) in both well-mixed and structured populations; (2) when the environment switches between two or more states. Furthermore, the environment changing rate decides if state-dependent strategies benefit global cooperation. The evolution sees the rise of the cooperation level for fast environment switching and the decrease otherwise. Our work stresses that individuals' perceptions of different environment states are beneficial to their survival and social prosperity in a changing world.


Asunto(s)
Evolución Biológica , Teoría del Juego , Conducta Cooperativa , Retroalimentación , Humanos , Probabilidad , Procesos Estocásticos
10.
Phys Chem Chem Phys ; 23(8): 4796-4804, 2021 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-33605280

RESUMEN

Titanium-based materials have been considered to be promising materials for many years. The structures and properties of TixOy and TiC at the nanoscale are important for studying the mechanism of formation of their nanoparticles. In this work, the density functional theory (DFT) method was used to calculate the structures of (TixOy)n (n = 1-5) and (TiC)n (n = 1-10) clusters. Based on these calculations, the formation pathways from (TiO2)n clusters to (TiO)n and (TiC)n clusters via carbon reduction were investigated. The results show that the pathway via (Ti2O3)n or (Ti3O5)n is the most likely pathway for the transformation of the (TiO2)n cluster to the (TiO)n cluster. The (TiO)n cluster is not the final product in the reduction process of (TiO2)n with C, and it can be finally transformed into (TiC)n clusters via various TinOxCy clusters via reaction with C. In addition, the (TiO2)n clusters can be transformed into (TiC)n clusters directly via various TixOyCz clusters.

11.
Glob Chang Biol ; 26(12): 7242-7254, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32986924

RESUMEN

The fate of soil organic carbon (SOC) under warming is poorly understood, particularly across large extents and in the whole-soil profile. Using a data-model integration approach applied across the globe, we find that downward movement of SOC along the soil profile reduces SOC loss under warming. We predict that global SOC stocks (down to 2 m) will decline by 4% (~80 Pg) on average when SOC reaches the steady state under 2°C warming, assuming no changes in net primary productivity (NPP). To compensate such decline (i.e. maintain current SOC stocks), a 3% increase of NPP is required. Without the downward SOC movement, global SOC declines by 15%, while a 20% increase in NPP is needed to compensate that loss. This vital role of downward SOC movement in controlling whole-soil profile SOC dynamics in response to warming is due to the protection afforded to downward-moving SOC by depth, indicated by much longer residence times of SOC in deeper layers. Additionally, we find that this protection could not be counteracted by promoted decomposition due to the priming of downward-moving new SOC from upper layers on native old SOC in deeper layers. This study provides the first estimation of whole-soil SOC changes under warming and additional NPP required to compensate such changes across the globe, and reveals the vital role of downward movement of SOC in reducing SOC loss under global warming.


Asunto(s)
Carbono , Suelo , Ciclo del Carbono , Calentamiento Global , Microbiología del Suelo
12.
Phys Chem Chem Phys ; 21(25): 13847-13855, 2019 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-31211308

RESUMEN

The crystallization process of CaO in iron melt begins with nucleation, which determines the structure and size of the CaO inclusions; thus, it is important to investigate the mechanism of inclusion modification by calcium treatment. In this study, a two-step nucleation method was used to investigate the behavior during the early stages of CaO inclusion crystallization. The first principles method was applied to calculate the structures and properties of CaO crystals and CaO clusters. Then, the nucleation mechanism of CaO in the Fe-O-Ca melt has been discussed. The numerical results show that CaO clusters with cubic structures and appropriate variations are the lowest energy structures and are more stable than other isomers. The stability of the cubic (CaO)n clusters increases with the increase in size and gradually approaches that of the CaO crystal. CaO clusters can form spontaneously in the Fe-O-Ca melt, while the transformation reaction of the CaO clusters in the Fe-O-Ca melt deeply depends on the supersaturation ratio of [Ca] and [O]. CaO clusters may remain as suspended CaO inclusions in the iron melt for a long time, and these suspensions of CaO clusters are the source of excess oxygen in the iron melt.

13.
Ecotoxicol Environ Saf ; 181: 130-137, 2019 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-31176247

RESUMEN

The pikeperch Sander lucioperca is an economically important freshwater species that is currently threatened by higher summer temperatures caused by global warming. To clarify the physiological state of pikeperch reared under relatively high temperatures and to acquire valuable biomarkers to monitor heat stress in this species, 100 fish were subjected to five different temperature treatments, ranging from 23 °C (control) to 36 °C. The physiological and biochemical indexes of liver and blood were determined, and heat-shock cognate 70 kDa protein (Hsc70) mRNA expression profiles were analyzed. The results showed that the activities of superoxide dismutase, catalase, and glutathione peroxidase in heat-stressed pikeperch first increased and then decreased, exhibiting peaks at 34 °C, 28 °C, and 28 °C, respectively. The level of thiobarbituric acid-reactive substances (TBARS) in all experimental groups was significantly higher than that of the control. The numbers of red blood cells, the packed-cell volume, and the contents of hemoglobin were significantly higher in the 34 °C and 36 °C treatment groups. Under heat stress, the albumin, cholesterol, and triglycerides contents decreased with increasing temperatures. Real-time fluorescence-based quantitative RT-PCR showed that Hsc70 mRNA levels increased in all eight of the tested tissues under heat stress. Expression reached maximum levels at 34 °C in the muscle, heart and gill tissues, and at 36 °C in the other five tissues. These results demonstrate that several physiological and biochemical phenotypes, such as oxidative stress, antioxidant enzymes and molecular chaperones, could be important biomarkers of heat stress in pikeperch, and are potentially valuable to uncover the mechanisms of heat-stress responses in fish.


Asunto(s)
Proteínas de Peces/metabolismo , Proteínas del Choque Térmico HSC70/metabolismo , Respuesta al Choque Térmico , Percas/metabolismo , Animales , Antioxidantes/metabolismo , Catalasa/metabolismo , Recuento de Eritrocitos , Proteínas de Peces/genética , Glutatión Peroxidasa/metabolismo , Proteínas del Choque Térmico HSC70/genética , Respuesta al Choque Térmico/genética , Hemoglobinas/análisis , Hígado/enzimología , Hígado/metabolismo , Estrés Oxidativo , Percas/genética , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo
14.
J Clin Lab Anal ; 31(5)2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27862350

RESUMEN

BACKGROUND: Reference intervals are critical for interpreting test results of a clinical laboratory. The aim of this study was to establish local reference intervals of complete blood count for healthy preschoolers in China. METHODS: Three thousand eight hundred and twenty-one blood specimens from children aged 4 months to 6 years were collected and analyzed. Complete blood counts were determined by Sysmex XT-4000i Automated Hematology Analyzer. The nonparametric 2.5th to 97.5th percentile reference ranges were calculated according to CLSI EP28-A3c guideline. RESULTS: Reference intervals for each blood cell parameter are determinded as follows: total WBC 4.86-12.1×109 /L for males and 4.73-12.3×109 /L for females; RBC 4.13-5.32×1012 /L for males and 4.08-5.24×1012 /L for females; HGB 109-145 g/L for males and 111-143 g/L for females; HCT 33.1-41.2% for males and 33.3-41.1% for females; MCH 23.5-29.7 pg for males and 24.6-30.0 pg for females; MCHC 320-365 g/L for males and 321-362 g/L for females; MCV 71.4-85.1 fL for males and 73.8-86.9 fL for females; RDW-SD 33.5-41.9 fL for males and 33.5-41.0 fL for females; RDW-CV 12.0-15.2% for males and 11.8-14.5% for females; PLT 181-475×109 /L for males and 179-456×109 /L for females; PCT 0.18-0.44% for males and 0.18-0.43% for females; MPV 8.20-11.6 fL for males and 8.20-11.5 fL for females; PDW 8.40-14.4 fL for males and 8.40-14.0 fL for females; P-LCR 12.0-36.6% for males and 11.8-35.6% for females. CONCLUSIONS: We established local complete blood count reference intervals for apparent healthy preschoolers in China. It is necessary to establishing region-specific reference intervals of complete blood count for preschoolers.


Asunto(s)
Pueblo Asiatico/estadística & datos numéricos , Recuento de Células Sanguíneas/estadística & datos numéricos , Recuento de Células Sanguíneas/normas , Niño , Preescolar , China/epidemiología , Femenino , Humanos , Lactante , Masculino , Valores de Referencia
15.
Int J Biometeorol ; 61(8): 1445-1460, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-28247124

RESUMEN

Climate change continually affects our capabilities to feed the increasing population. Rising temperatures have the potential to shorten the crop growth duration and therefore reduce crop yields. In the past decades, China has successfully improved crop cultivars to stabilize, and even lengthen, the crop growth duration to make use of increasing heat resources. However, because of the complex cropping systems in the different regions of China, the possibility and the effectiveness of regulating crop growth duration to reduce the negative impacts of future climate change remain questionable. Here, we performed a projective analysis of the staple food crop productivity in double-rice, wheat-rice, wheat-maize, single-rice, and single-maize cropping systems in China using modeling approaches. The results indicated that from the present to the 2040s, the warming climate would shorten the growth duration of the current rice, wheat, and maize cultivars by 2-24, 11-13, and 9-29 days, respectively. The most significant shortening of the crop growth duration would be in Northeast China, where single-rice and single-maize cropping dominates the croplands. The shortened crop growth duration would consequently reduce crop productivity. The most significant decreases would be 27-31, 6-20, and 7-22% for the late crop in the double-rice rotation, wheat in the winter wheat-rice rotation, and single maize, respectively. However, our projection analysis also showed that the negative effects of the warming climate could be compensated for by stabilizing the growth duration of the crops via improvement in crop cultivars. In this case, the productivity of rice, wheat, and maize in the 2040s would increase by 4-16, 31-38, and 11-12%, respectively. Our modeling results implied that the possibility of securing future food production exists by adopting proper adaptation options in China.


Asunto(s)
Cambio Climático , Productos Agrícolas/crecimiento & desarrollo , Modelos Teóricos , Agricultura/métodos , China , Oryza/crecimiento & desarrollo , Triticum/crecimiento & desarrollo , Zea mays/crecimiento & desarrollo
16.
J Environ Sci (China) ; 57: 356-369, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28647257

RESUMEN

Reliable national estimates of CH4 emissions from natural wetlands depend on model validation based on site observations. We therefore evaluated the performance of the CH4MODwetland model in simulating CH4 emissions from 11 representative wetland sites in five regions of China. Model performance analysis showed that this method effectively simulates differences in the CH4 fluxes between different sites and regions. The model efficiency for estimating the daily CH4 fluxes in the northeastern China (NE), Inner Mongolia and northwestern China (NW), the North China plain and the Middle-Lower Yangtze Plain (E) and the Qinghai Tibetan Plateau (SW) was 0.51, 0.20, 0.52 and 0.65, respectively. The efficiency for estimating the annual mean CH4 fluxes in southern China (S) was 0.99. Systematic negative deviation between the simulated and observed CH4 emissions existed in all regions, especially in the NW region, which had a mean deviation (RMD) value of -36.7%. On the national scale, the root mean square error (RMSE), the RMD, the model efficiency (EF) between the simulated and observed seasonal values were 28.7%, -7.8% and 0.93, respectively. The CH4 emissions showed the highest sensitivity to air temperature in the NE and SW regions, and to water table depth in the E region. Based on the sensitivity analysis, future climate warming and wetting are likely to increase the wetland CH4 emissions at different levels in all regions of China.


Asunto(s)
Eliminación de Residuos Líquidos/métodos , Humedales , Contaminantes Atmosféricos/análisis , China , Clima , Monitoreo del Ambiente , Metano/análisis , Modelos Teóricos , Estaciones del Año
17.
Opt Express ; 24(6): A581-91, 2016 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-27136878

RESUMEN

Simultaneous wind and temperature measurements in stratosphere with high time-spatial resolution for gravity waves study are scarce. In this paper we perform wind field gravity waves cases in the stratosphere observed by a mobile Rayleigh Doppler lidar. This lidar system with both wind and temperature measurements were implemented for atmosphere gravity waves research in the altitude region 15-60 km. Observations were carried out for two periods of time: 3 months started from November 4, 2014 in Xinzhou, China (38.425°N,112.729°E) and 2 months started from October 7, 2015 in Jiuquan, China (39.741°N, 98.495°E) . The mesoscale fluctuations of the horizontal wind velocity and the two dimensional spectra analysis of these fluctuations show the presence of dominant oscillatory modes with wavelength of 4-14 km and period of around 10 hours in several cases. The simultaneous temperature observations make it possible to identify gravity wave cases from the relationships between different variables: temperature and horizontal wind. The observed cases demonstrate the Rayleigh Doppler Lidar's capacity to study gravity waves.

18.
Anticancer Drugs ; 27(1): 1-8, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26426520

RESUMEN

Temozolomide (TMZ) combination with whole-brain radiotherapy (WBRT) has been tested by many randomized controlled trials in the treatment of brain metastases (BMs) in China and other countries. We performed an up-to-date meta-analysis to determine (i) the log odds ratios (LORs) of objective response (ORR) and adverse effects (AEs) for all-grade, and (ii) the T value of mean overall survival in patients with BMs treated with WBRT combined with TMZ versus WBRT alone. PubMed, Chinese National Knowledge Infrastructure, and WanFang Data were searched for articles published up to 28 January 2015. Eligible studies were selected according to the PRISMA statement. ORR, AEs, and 95% confidence intervals were calculated using random-effects models. Eighteen studies were included in our analysis. A total of 1028 participants were enrolled. Summary LORs of ORR were 1.0239 (P<0.0001) on comparing WBRT plus TMZ with WBRT ORR (n=17). The overall mean difference of mean overall survival (n=17) between TMZ plus WBRT and WBRT was 2.2505 weeks (P=0.02185). There was a significant difference between WBRT plus TMZ and WBRT alone with a LOR of AEs for all-grade of (i) 0.923 for gastrointestinal toxicity and (ii) 0.7978 for myelosuppression. Sensitivity analysis and subgroup analysis were also performed. The 18 eligible randomized controlled trials demonstrated that the combination of WBRT and TMZ significantly improves the ORR and is statistically insignificant in prolonging the survival of patients with BMs. In addition, an increase in the incidence of gastrointestinal toxicity and myelosuppression was significant for all-grade.


Asunto(s)
Antineoplásicos Alquilantes/uso terapéutico , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/radioterapia , Dacarbazina/análogos & derivados , Neoplasias Encefálicas/secundario , Terapia Combinada , Dacarbazina/uso terapéutico , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto , Temozolomida
19.
AAPS PharmSciTech ; 16(5): 1051-8, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25652729

RESUMEN

AJS is the code name of an untitled novel medicative compound synthesized by the Tasly Holding Group Company (Tianjin, China) based on the structure of cinnamamide, which is one of the Biopharmaceutics Classification System (BCS) class II drugs. The drug has better antidepressant effect, achieved by acting on the 5-hydroxytryptamine receptor. However, the therapeutic effects of the drug are compromised due to its poor water solubility and lower bioavailability. Herein, a self-microemulsifying drug delivery system (SMEDDS) was developed to improve its solubility and oral bioavailability. AJS-SMEDDS formulation was optimized in terms of drug solubility in the excipients, droplet size, stability, and drug precipitation using a pseudo-ternary diagram. The pharmacokinetic study was performed in rats, and the drug concentration in plasma samples was assayed using the high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-MS/MS) method. The optimized formulation for SMEDDS has a composition of castor oil 24.5%, Labrasol 28.6%, Cremphor EL 40.8%, and Transcutol HP 2.7% (co-surfactant). No drug precipitation or phase separation was observed from the optimized formulation after 3 months of storing at 25°C. The droplet size of microemulsion formed by the optimized formulation was 26.08 ± 1.68 nm, and the zeta potential was -2.76 mV. The oral bioavailability of AJS-SMEDDS was increased by 3.4- and 35.9-fold, respectively, compared with the solid dispersion and cyclodextrin inclusion; meanwhile, the C max of AJS-SMEDDS was about 2- and 40-fold as great as the two controls, respectively. In summary, the present SMEDDS enhanced oral bioavailability of AJS and was a promising strategy to orally deliver the drug.


Asunto(s)
Antidepresivos/farmacocinética , Cinamatos/farmacocinética , Portadores de Fármacos , Sistemas de Liberación de Medicamentos/instrumentación , Administración Oral , Animales , Antidepresivos/administración & dosificación , Antidepresivos/sangre , Antidepresivos/química , Disponibilidad Biológica , Cromatografía Líquida de Alta Presión , Cinamatos/administración & dosificación , Cinamatos/sangre , Cinamatos/química , Composición de Medicamentos , Estabilidad de Medicamentos , Almacenaje de Medicamentos , Emulsiones , Nanopartículas , Ratas Wistar , Solubilidad , Espectrometría de Masa por Ionización de Electrospray , Tensoactivos/química , Espectrometría de Masas en Tándem , Temperatura , Viscosidad
20.
Bioorg Med Chem Lett ; 24(22): 5284-7, 2014 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-25442321

RESUMEN

Cinnamamide 3a, a leading compound with antidepressant-like activity, and its derivatives were synthesized and their antidepressant activity and structure-activity relationship were investigated. Most of the compounds with trifluoromethyl group in methylenedioxyphenyl moiety (3f, 4b-c and 6a-b) exhibited significant antidepressant activity, measured in terms of percentage decrease in immobility duration by tail suspension test. In addition, the dose-dependent antidepressant effect of the most potent compound 3f was subsequently confirmed in tail suspension test and forced swim test. The test results showed that 3f was equal to or more effective than the standard drug fluoxetine at a concentration of 10mg/kg. Furthermore, compound 3f did not show any central nervous system stimulant properties in the open-field test and the preliminary results were promising enough to warrant further detailed antidepressant research around this scaffold.


Asunto(s)
Antidepresivos/síntesis química , Cinamatos/química , Animales , Antidepresivos/química , Antidepresivos/farmacología , Conducta Animal/efectos de los fármacos , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Productos Biológicos/farmacología , Cinamatos/síntesis química , Cinamatos/farmacología , Ratones , Piper/química , Piper/metabolismo , Relación Estructura-Actividad
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA