In situ growth strategy for highly efficient Ag2CO3/g-C3N4 hetero/nanojunctions with enhanced photocatalytic activity under sunlight irradiation

Developing novel heterojunction photocatalysts is a powerful strategy for improving the separation efficiency of photogenerated charge carriers, which is attracting the intense research interest in photocatalysis. Herein we report a highly efficient hetero/nanojunction consisting of Ag2CO3 nanoparticles grown on layered g-C3N4 nanosheets synthesized via a facile and template free in situ precipitation method. The UV–vis diffuse reflectance studies revealed that the synthesized Ag2CO3/g-C3N4 hetero/nanojunctions exhibit a broader and stronger light absorption in the visible light region, which is highly beneficial for absorbing the visible light in the solar spectrum. The optimum photocatalytic activity of Ag2CO3/g-C3N4 at a weight content of 10% Ag2CO3 for the degradation of Rhodamine B was almost 5.5 and 4 times as high as that of the pure Ag2CO3 and g-C3N4, respectively. The enhanced photocatalytic activity of the Ag2CO3/g-C3N4 hetero/nanojunctions is due to synergistic effects including the strong visible light absorption, large specific surface area, and high charge transfer and separation efficiency. More importantly, the high photostability and low use of the noble metal silver which reduces the cost of the material. Therefore, the synthesized Ag2CO3/g-C3N4 hetero/nanojunction photocatalyst is a promising candidate for energy storage and environment protection applications.

"Nucleosome debris" provokes coagulation and inflammation

Editorial

Évaluation de marqueurs plasmatiques de l'activation de la coagulation chez des chats atteints de cardiomyopathie

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Development and Characterization of Monovalent and Bivalent RNA Aptamers Targeting the Common Pathway of Coagulation

Anticoagulant agents are commonly used drugs to reduce blood coagulation in acute and chronic clinical settings. Many of these drugs target the common pathway of coagulation because it is critical for thrombin generation and disruption of this portion of the pathway has profound effects on the hemostatic process. Currently available drugs for these indications struggle with balancing desired activity with immunogenicity and poor reversibility or irreversibility in the event of hemorrhage. While improvements are being made with the current drugs, new drugs with better therapeutic indices are needed for surgical intervention and chronic indications to prevent thrombosis from occurring.

A class of therapeutics known as aptamers may be able to meet the need for safer anticoagulant agents. Aptamer are short single-stranded RNA oligonucleotides that adopt specific secondary and tertiary structures based upon their sequence. They can be generated to both enzymes and cofactors because they derive their inhibitory activity by blocking protein-protein interactions, rather than active site inhibition. They inhibit their target proteins with a high level of specificity and bind with high affinity to their target. Additionally, they can be reversed using two different antidote approaches, specific oligonucleotide antidotes, or with cationic, “universal” antidotes. The reversal of their activity is both rapid and durable.

The ability of aptamers to be generated to cofactors has been conclusively proven by generating an aptamer targeting the common pathway coagulation cofactor, Factor V (FV). We developed two aptamers with anticoagulant ability that bind to both FV and FVa, the active cofactor. Both aptamers were truncated to smaller functional sizes and had specific point mutant aptamers developed for use as controls. The anticoagulant activity of both aptamer-mutant pairs was characterized using plasma-based clotting assays and whole blood assays. The mechanism of action resulting in anticoagulant activity was assessed for one aptamer. The aptamer was found to block FVa docking to membrane surfaces, a mechanism not previously observed in any of our other anticoagulant aptamers.

To explore development of aptamers as anticoagulant agents targeting the common pathway for surgical interventions, we fused two anticoagulant aptamers targeting Factor X and prothrombin into a single molecule. The bivalent aptamer was truncated to a minimal size while maintaining robust anticoagulant activity. Characterization of the bivalent aptamer in plasma-based clotting assays indicated we had generated a very robust anticoagulant therapeutic. Furthermore, we were able to simultaneously reverse the activity of both aptamers with a single oligonucleotide antidote. This rapid and complete reversal of anticoagulant activity is not available in the antithrombotic agents currently used in surgery.

Évaluation de marqueurs plasmatiques de l'activation de la coagulation chez des chats atteints de cardiomyopathie

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

A novel coagulation inhibitor from Schistosoma japonicum

Little is known about the molecular mechanisms whereby the human blood fluke Schistosoma japonicum is able to survive in the host venous blood system. Protease inhibitors are likely released by the parasite enabling it to avoid attack by host proteolytic enzymes and coagulation factors. Interrogation of the S. japonicum genomic sequence identified a gene, SjKI-1, homologous to that encoding a single domain Kunitz protein (Sjp_0020270) which we expressed in recombinant form in Escherichia coli and purified. SjKI-1 is highly transcribed in adult worms and eggs but its expression was very low in cercariae and schistosomula. In situ immunolocalization with anti-SjKI-1 rabbit antibodies showed the protein was present in eggs trapped in the infected mouse intestinal wall. In functional assays, SjKI-1 inhibited trypsin in the picomolar range and chymotrypsin, neutrophil elastase, FXa and plasma kallikrein in the nanomolar range. Furthermore, SjKI-1, at a concentration of 7·5 µ m, prolonged 2-fold activated partial thromboplastin time of human blood coagulation. We also demonstrate that SjKI-1 has the ability to bind Ca(++). We present, therefore, characterization of the first Kunitz protein from S. japonicum which we show has an anti-coagulant properties. In addition, its inhibition of neutrophil elastase indicates SjKI-1 have an anti-inflammatory role. Having anti-thrombotic properties, SjKI-1 may point the way towards novel treatment for hemostatic disorders.

An introduction to mathematical models of coagulation-fragmentation processes: a discrete deterministic mean-field approach

We summarise the properties and the fundamental mathematical results associated with basic models which describe coagulation and fragmentation processes in a deterministic manner and in which cluster size is a discrete quantity (an integer multiple of some basic unit size). In particular, we discuss Smoluchowski's equation for aggregation, the Becker-Döring model of simultaneous aggregation and fragmentation, and more general models involving coagulation and fragmentation.

Coagulation equations with mass loss

We derive and solve models for coagulation with mass loss arising, for example, from industrial processes in which growing inclusions are lost from the melt by colliding with the wall of the vessel. We consider a variety of loss laws and a variety of coagulation kernels, deriving exact results where possible, and more generally reducing the equations to similarity solutions valid in the large-time limit. One notable result is the effect that mass removal has on gelation: for small loss rates, gelation is delayed, whilst above a critical threshold, gelation is completely prevented. Finally, by forming an exact explicit solution for a more general initial cluster size distribution function, we illustrate how numerical results from earlier work can be interpreted in the light of the theory presented herein.

Effects of coagulation factors and inflammatory cytokines on development of acute myocardial infarction in patients younger than 60 years

Purpose: To investigate the effects of coagulation factors and inflammatory cytokines on acute myocardial infarction (AMI) development in patients younger than 60 years. Methods: In this study, 60 patients admitted to The First Affiliated Hospital of Dalian Medical University (Dalian, China) with AMI and 30 other subjects matched with the patients for age and ethnicity but without AMI were enrolled. Blood samples were collected from the AMI patients and the control subjects after a 12-h fast. Subsequently, the levels of coagulation factors (F) II (FII), VII (FVII), VIII (FVIII), fibrinogen (Fg) and von Willebrand factor (vWF) in plasma were analyzed by enzyme-linked immunosorbent assay (ELISA). The protein expression levels of these coagulation factors were determined by Western blot analysis. Inflammatory factors including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin- 6 (IL-6) were also measured by ELISA. Results: FII, FVII, FVIII, Fg and vWF levels in plasm were significantly higher in AMI patients compared with control subjects (p < 0.01). Furthermore, the protein expression levels of FII, FVII, FVIII, Fg and vWF were also significantly up-regulated in AMI patients compared with those in control subjects. Additionally, no significant difference was observed in CRP between AMI patients and control subjects (p > 0.05). However, TNF-α and IL-6 levels in the plasma of AMI patients were significantly higher than those in control subjects (p < 0.05). Conclusion: The results reveal that the pathogenesis of AMI in patients younger than 60 years might be closely related to the high levels of coagulation factors and inflammatory cytokines in the blood.

Relación de la enzima alfa-amilasa salivar con la presencia de sintomatología psicopatologica internalizada auto- y hetero-observada en una muestra de niños y niñas de entre 7 y 12 años de edad: un estudio piloto.

Introducción: La medición de la actividad enzimática (AAAs) y del flujo de secreción (FSAAs) de la enzima alfa-amilasa salivar han sido propuestos por diversos grupos de investigación como posibles marcadores biológicos indirectos, no invasivos, y de bajo coste, del nivel de actividad noradrenérgica periférica/central. Dicha actividad noradrenérgica se sustenta, esencialmente, gracias a la actividad preponderante del denominado Sistema Locus Coeruleus-Noradrenalina (LC-NA), un sistema básico en la modulación de diversas funciones atencionales, cognitivas ejecutivas, así como en la regulación de los estados de ánimo. Material y Método: En nuestro estudio piloto (N = 13; 9 niños, 4 niñas; Edad media ± DT = 10,23 ± 1,53) se analizó la relación entre ambos marcadores salivares junto al parámetro flujo de secreción salivar total (registrados a lo largo de un proceso de evaluación neuropsicológica escolar) y diversas medidas auto (CDI; ansiedad, depresión y depresión total) y hetero-reportadas (escalas de psicopatología internalizada del TRF: ansiedad- depresión, depresión-aislamiento, alteraciones psicosomáticas y psicopatología internalizante total). Resultados: Los análisis estadísticos basados en el cálculo de coeficientes de correlación producto-momento de Pearson (de tipo parcial al controlar el efecto de la variable IMC), revelaron correlaciones estadísticamente significativas y directas entre el FSAAs y las puntuaciones en la escala ansiedad-depresión (p < 0,039) y psicopatología internalizante total del TRF (p < 0,012), así como una tendencia a la significación en el caso de las puntuaciones para la escala de alteraciones psicosomáticas (p = 0,054) de esa misma prueba. Del mismo modo, se observaron tendencias a la significación en la asociación directa entre las subescalas ansiedad-depresión (p = 0.065) y psicopatología internalizante total (p = 0.083) y la medida del flujo salivar total. Por otro lado, se observaron asociaciones inversas estadísticamente significativas entre la variable flujo salivar total y las puntuaciones de ansiedad (p < 0.01) y depresión total (p < 0.01) obtenidas a través del CDI. Discusión: Estos resultados preliminares de este estudio piloto abren una interesante línea de trabajo en nuestro laboratorio acerca de la utilidad de la medición de la AAAs, FSAAs y FST como posibles marcadores biológicos, no invasivos, y de bajo coste, aptos para su empleo con poblaciones pediátricas. Dichos marcadores, están relacionados con el grado de actividad noradrenérgica periférica/central desarrollada por el sistema LC y con la actividad del SNV, que a su vez están implicados en la regulación de los estados afectivos. Estudios recientes han mostrado bajos niveles basales de alfa-amilasa salivar en el caso de pacientes jóvenes diagnosticados de su primer episodio depresivo (Cubala y Landoski, 2014) y en participantes infantiles con mayor sintomatología depresiva heteroobservada (Vigil et al., 2006; Maldonado et al., 2014; Maldonado, enviado). Estos resultados complementan las observaciones realizadas anteriormente por nuestra laboratorio (Maldonado et al., 2014; Maldonado, enviado).

New particle formation and growth at a remote, sub-tropical coastal location

A month-long intensive measurement campaign was conducted in March/April 2007 at Agnes Water, a remote coastal site just south of the Great Barrier Reef on the east coast of Australia. Particle and ion size distributions were continuously measured during the campaign. Coastal nucleation events were observed in clean, marine air masses coming from the south-east on 65% of the days. The events usually began at ~10:00 local time and lasted for 1-4 hrs. They were characterised by the appearance of a nucleation mode with a peak diameter of ~10 nm. The freshly nucleated particles grew within 1-4 hrs up to sizes of 20-50 nm. The events occurred when solar intensity was high (~1000 W m-2) and RH was low (~60%). Interestingly, the events were not related to tide height. The volatile and hygroscopic properties of freshly nucleated particles (17-22.5 nm), simultaneously measured with a volatility-hygroscopicity-tandem differential mobility analyser (VH-TDMA), were used to infer chemical composition. The majority of the volume of these particles was attributed to internally mixed sulphate and organic components. After ruling out coagulation as a source of significant particle growth, we conclude that the condensation of sulphate and/or organic vapours was most likely responsible for driving particle growth during the nucleation events. We cannot make any direct conclusions regarding the chemical species that participated in the initial particle nucleation. However, we suggest that nucleation may have resulted from the photo-oxidation products of unknown sulphur or organic vapours emitted from the waters of Hervey Bay, or from the formation of DMS-derived sulphate clusters over the open ocean that were activated to observable particles by condensable vapours emitted from the nutrient rich waters around Fraser Island or Hervey Bay. Furthermore, a unique and particularly strong nucleation event was observed during northerly wind. The event began early one morning (08:00) and lasted almost the entire day resulting in the production of a large number of ~80 nm particles (average modal concentration during the event was 3200 cm-3). The Great Barrier Reef was the most likely source of precursor vapours responsible for this event.

Investigation into submicrometer particle and gaseous emissions from airport ground running procedures

Emissions from airport operations are of significant concern because of their potential impact on local air quality and human health. The currently limited scientific knowledge of aircraft emissions is an important issue worldwide, when considering air pollution associated with airport operation, and this is especially so for ultrafine particles. This limited knowledge is due to scientific complexities associated with measuring aircraft emissions during normal operations on the ground. In particular this type of research has required the development of novel sampling techniques which must take into account aircraft plume dispersion and dilution as well as the various particle dynamics that can affect the measurements of the aircraft engine plume from an operational aircraft. In order to address this scientific problem, a novel mobile emission measurement method called the Plume Capture and Analysis System (PCAS), was developed and tested. The PCAS permits the capture and analysis of aircraft exhaust during ground level operations including landing, taxiing, takeoff and idle. The PCAS uses a sampling bag to temporarily store a sample, providing sufficient time to utilize sensitive but slow instrumental techniques to be employed to measure gas and particle emissions simultaneously and to record detailed particle size distributions. The challenges in relation to the development of the technique include complexities associated with the assessment of the various particle loss and deposition mechanisms which are active during storage in the PCAS. Laboratory based assessment of the method showed that the bag sampling technique can be used to accurately measure particle emissions (e.g. particle number, mass and size distribution) from a moving aircraft or vehicle. Further assessment of the sensitivity of PCAS results to distance from the source and plume concentration was conducted in the airfield with taxiing aircraft. The results showed that the PCAS is a robust method capable of capturing the plume in only 10 seconds. The PCAS is able to account for aircraft plume dispersion and dilution at distances of 60 to 180 meters downwind of moving a aircraft along with particle deposition loss mechanisms during the measurements. Characterization of the plume in terms of particle number, mass (PM2.5), gaseous emissions and particle size distribution takes only 5 minutes allowing large numbers of tests to be completed in a short time. The results were broadly consistent and compared well with the available data. Comprehensive measurements and analyses of the aircraft plumes during various modes of the landing and takeoff (LTO) cycle (e.g. idle, taxi, landing and takeoff) were conducted at Brisbane Airport (BNE). Gaseous (NOx, CO2) emission factors, particle number and mass (PM2.5) emission factors and size distributions were determined for a range of Boeing and Airbus aircraft, as a function of aircraft type and engine thrust level. The scientific complexities including the analysis of the often multimodal particle size distributions to describe the contributions of different particle source processes during the various stages of aircraft operation were addressed through comprehensive data analysis and interpretation. The measurement results were used to develop an inventory of aircraft emissions at BNE, including all modes of the aircraft LTO cycle and ground running procedures (GRP). Measurements of the actual duration of aircraft activity in each mode of operation (time-in-mode) and compiling a comprehensive matrix of gas and particle emission rates as a function of aircraft type and engine thrust level for real world situations was crucial for developing the inventory. The significance of the resulting matrix of emission rates in this study lies in the estimate it provides of the annual particle emissions due to aircraft operations, especially in terms of particle number. In summary, this PhD thesis presents for the first time a comprehensive study of the particle and NOx emission factors and rates along with the particle size distributions from aircraft operations and provides a basis for estimating such emissions at other airports. This is a significant addition to the scientific knowledge in terms of particle emissions from aircraft operations, since the standard particle number emissions rates are not currently available for aircraft activities.