Moderate Temperature Increase Research Articles

The Influence of the Spatial Scale on the Fishery Landings-SST Relationship

Possible effects of the spatial scale of analysis on the relationship between fishery landings and the water temperature in the Mediterranean Sea have been investigated using the FAO capture database (1970-2010). The analysis was performed by dividing species in three thermal affinity categories: cold, temperate and hot species. Results showed significant changes in fishery landings composition during the last four decades, in terms of the relative contribution of cold, temperate and hot species to landings; moreover, the presence of a strong influence of water warming in determining the landings temporal pattern has been confirmed. This relationship, however, resulted to be not homogenous across the tested spatial scales (entire Mediterranean basin, three main sub-basins, eight FAO areas). The best models (based on the Akaike Information Criterion), were the ones fitted at the finer spatial definition (i.e. the eight FAO areas) for all the three thermal affinity categories. The recorded relationship showed clear differences in terms of direction, depending on both areas and thermal affinity groups. Cold species showed a negative relationship with the increasing water temperature in all the FAO areas, being partially replaced by temperate ones, with the exception of the Adriatic and Black Sea (the coldest areas in the Mediterranean basin), where a moderate increase in the water temperature is still favoring the cold affinity group. This kind of results could be useful within the context of the management plans definition, within a context of climate changes.

Near-future ocean acidification enhances the feeding rate and development of the herbivorous juveniles of the crown-of-thorns starfish, Acanthaster planci

Population outbreaks of the corallivorous crown-of-thorns starfish, Acanthaster planci, are a major contributor to the decline in coral reef across the Indo-Pacific. The success of A. planci and other reef species in a changing ocean will be influenced by juvenile performance because the naturally high mortality experienced at this sensitive life history stage maybe exacerbated by ocean warming and acidification. We investigated the effects of increased temperature and acidification on growth of newly metamorphosed juvenile A. planci and their feeding rates on crustose coralline algae (CCA) during the initial herbivorous phase of their life history. The juveniles were exposed to three temperature (26, 28, 30 °C) and three pH (NIST scale: 8.1, 7.8, 7.6) levels in a flow-through cross-factorial experiment. There were positive but independent effects of warming and acidification on juvenile growth and feeding. Early juveniles were highly tolerant to moderate increases in temperature (+2 °C above ambient) with the highest growth at 30 °C. Growth and feeding rates of A. planci on CCA were highest at pH 7.6. Thus, ocean warming and acidification may enhance the success of A. planci juveniles. In contrast to its coral prey, at this vulnerable developmental stage, A. planci appears to be highly resilient to future ocean change. Success of juveniles in a future ocean may have carry-over effects into the coral-eating life stage, increasing the threat to coral reef systems.

Investigating the impact of land-use land-cover change on Indian summer monsoon daily rainfall and temperature during 1951–2005 using a regional climate model

Abstract. Daily moderate rainfall events, which constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 through 2005. On the other hand, mean and extreme near-surface daily temperature during the monsoon season have increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4) and prescribed land cover of years 1950 and 2005, it is demonstrated that part of the changes in moderate rainfall events and temperature have been caused by land-use/land-cover change (LULCC), which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over central India coincides with the region of decrease in forest and increase in crop cover. Our results also show that LULCC alone causes warming in the extremes of daily mean and maximum temperatures by a maximum of 1–1.2 °C, which is comparable with the observed increasing trend in the extremes. Decrease in forest cover and simultaneous increase in crops not only reduces the evapotranspiration over land and large-scale convective instability, but also contributes toward decrease in moisture convergence through reduced surface roughness. These factors act together in reducing significantly the moderate rainfall events and the amount of rainfall in that category over central India. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures over the Indian Ocean. As a result, enhanced warming at the surface and greater decrease in moderate rainfall events over central India compared to the earlier set of simulations are noticed. Results from these additional experiments corroborate our initial findings and confirm the contribution of LULCC in the decrease in moderate rainfall events and increase in daily mean and extreme temperature over India. Therefore, this study demonstrates the important implications of LULCC over India during the monsoon season. Although, the regional climate model helps in better resolving land–atmosphere feedbacks over the Indian region, the inferences do depend on the fidelity of the model in capturing the features of Indian monsoon realistically. It is proposed that similar studies using a suite of climate models will further enrich our understanding about the role of LULCC in the Indian monsoon climate.

Hsp60 expression profiles in the reef-building coral Seriatopora caliendrum subjected to heat and cold shock regimes

Climate changes have increased the intensity/frequency of extreme thermal events, which represent serious threats to the health of reef-building corals. Since the vulnerability of corals exposed to thermal stresses are related to their ability to regulate Heat shock proteins (Hsps), we have analyzed together the time related expression profiles of the mitochondrial Hsp60 and the associated changes in tissue pigmentation in Seriatopora caliendrum subjected to 48 h of heat and cold treatments characterized by moderate (±2 °C) and severe (±6 °C) shocks. For the first time, an Hsp60 response was observed in a scleractinian coral exposed to cold stresses. Furthermore, the Hsp60 modulations and the changes in the tissue coloration were found to be specific for each treatment. A strong down-regulation at the end of the treatments was observed following both the severe shocks, but only the severe heat stress led to bleaching in concert with the lowest levels of Hsp60, suggesting that a severe heat shock can be more deleterious than an exposure to a severe cold temperature. On the contrary, a moderate cold stress seems to be more harmful than a moderate temperature increase, which could allow coral acclimation. Our results can provide a potential framework for understanding the physiological tolerance of corals under possible future climate changes.

Thermal transitions and molecular dynamics in main‐chain liquid crystalline polyester/fullerene nanocomposites

Molecular dynamics and liquid crystalline (LC) transitions in nanocomposites with main‐chain liquid crystalline alkylene–aromatic polyester as a matrix and fullerene C60 as a filler, with filler content varying from 0.3 up to 5 wt% were studied. Measurements by differential scanning calorimetry (DSC) and temperature modulated DSC techniques were performed in order to study glass transition and LC transitions. Dielectric relaxation spectroscopy (DRS) was used both to record LC transitions through isochronal measurements at four different frequencies during cooling/heating at constant rate and to study molecular mobility through isothermal measurements in a wide temperature and frequency range, −150°C to 190°C and 10−1 to 106 Hz, respectively. Glass transition and LC transitions were followed for the neat matrix as well as for the nanocomposites. A moderate increase of glass transition temperature in nanocomposites was found, while the LC transitions were shifted to lower temperatures with increasing filler content. A good correlation between DSC and DRS results was found. For all the samples under study four dielectric relaxations were followed by DRS, in order of increasing temperature: two secondary relaxations, β and γ, the α‐relaxation related to the amorphous phase glass transition and an interfacial relaxation (Maxwell–Wagner–Sillars, MWS) due to charge accumulation at the amorphous–crystalline interface. The experimental data were analyzed in detail and the results revealed rather weak effects of fullerenes on molecular dynamics. POLYM. COMPOS., 38:E331–E341, 2017. © 2016 Society of Plastics Engineers

Modeling and simulation of temperature-dependent cyclic plastic deformation of austenitic stainless steels at the VHCF limit

The exploration of fatigue mechanisms in the VHCF regime is gaining importance since many components have to withstand a very high number of loading cycles due to high frequency or long product life. In this regime, the period of fatigue crack initiation and thus the localization of plastic deformation play an important role. The material that was investigated in this study is the metastable austenitic stainless steel AISI 304 in the initially purely austenitic condition. The experimental investigations during quasi-isothermal fatigue tests revealed that a moderate increase of temperature from room temperature up to 150°C led to a reduced VHCF strength. At both temperatures the 304 grade still undergoes a pronounced localization of plastic deformation in shear bands accompanied by a deformation-induced martensitic phase transformation from the γ-austenite to the α’-martensite during VHCF loading. In the present study, the experimental study is extended by modeling and simulation of the relevant temperature-dependent VHCF deformation mechanisms in order to provide a more profound understanding of the observed cyclic deformation. For this purpose, two-dimensional (2-D) morphologies of microstructures are modeled in the mesoscopic scale by the use of the boundary element method (BEM), and cyclic plastic deformation is considered by certain mechanisms defined in a simulation model. It describes the localization of plastic deformation in shear bands taking into account the formation, plastic sliding deformation and cyclic slip irreversibility of each shear band. The deformation-induced martensitic phase transformation is represented by introducing martensitic nuclei into the modeled microstructure depending on the plastic deformation in shear bands. The influence of temperature is incorporated into the simulation model by the use of empirical data and a kinetic model, each related to the tensile test. The simulated cyclic deformation and phase transformation is compared to experimental observations and allows for assessing the individual influence of deformation mechanisms on the temperature-dependent fatigue behavior. Finally, a temperature-independent ‘limit curve’ for the accumulated irreversible plastic sliding deformation regarding failure in the VHCF regime is proposed.

気象観測点における土地被覆状況と地域微気候の関係

In recent years, global warming and the urban heat island phenomenon have become a serious problem not only in urban cities but also in local cities in Japan. One of the main causes is the change in land cover especially the loss of natural cover such as green spaces and water bodies and increase of artificial land cover such as buildings and asphalt coverage. In this study, we aimed to extract the degree of influence of the heat island phenomenon on the air temperature by analyzing the change in land cover and climate over the past 30 years across Japan. The study investigated the factors that influenced change in temperature at 288 weather observation points. Climate classification and geographical features analysis of all the stations was conducted. The results showed that the pacific side to the north from central Japan experienced a severe rise in temperature. Furthermore, the results showed that there was a moderate increase in temperature at points close to high altitude or latitude areas. In addition, we confirmed restraint in temperature at points close to the sea which were influenced by the effect of the water body. Investigation of the relationship between land cover and climate change showed that in the past 15 years there were many weather stations where there was decrease in natural land cover such as green spaces and an increase in artificial land cover. Moreover, in comparison to points with higher percentage of green cover, points with a higher percentage of artificial land cover showed a more rapid increase in air temperature. degree at which urban heat island phenomenon affects temperature was extracted from the yearly change in land cover of the selected regions. The results showed that in the period between 1985 to 2000, the average temperature gradient was 0.008°C per year. 14.3% of the temperature rise within the period was caused but the urban heat island phenomenon. In the period between 2000 to 2014, the average temperature gradient was 0.002°C per year. 22.2% of the temperature rise within the period was caused by the increase in urban heat phenomenon. Furthermore, as a secondary result, we found that after a certain percentage of green land cover is exceeded, the effect of restriction of temperature increase reaches its absolute peak. In order to understand the degree at which certain factors influence the air temperature increase, land cover condition, geographical features and wind patterns were stipulated as influencing factors. We quantified these factors and analyzed them using Hayashi's Quantification Method I. The analysis showed that latitude and land cover change had the greatest influence on the air temperature. From the above, this study extracted the degree at which the urban heat island phenomenon influences the temperature increase. In addition, we confirmed the influence of land cover change on the microclimate in an area. However, we could not analyze all the weather stations across Japan due to lack of satellite images in some points. Therefore, inclusion and analysis of these points and detailed investigation of the directional temperature around the weather stations are some of the points for further improvement in this study.

Uncertainty and Reliability Analysis of CMIP5 Climate Projections in South Korea Using REA Method

Weighting criteria methods achieved popularity in the quantification of uncertainty in the first decade of 21st century. In this study, Reliability Ensemble Averaging (REA) method is used to provide a quantitative estimate of uncertainty range and reliability of future climate projections over Han river basin in Korea simulated by 18 GCMs under CMIP5 Project. The root mean square error (RMSE) was used to measure uncertainty range. The result indicates that historical simulations project 43% decrease in precipitation while future scenarios simulations of GCMs projects a moderate increase in mean annual temperature and precipitation. The future projections showed a reduction in uncertainty range of about 150% as compared to simple ensemble average approach. The results suggest the viability of REA method by incorporating the model performance and model convergence criteria.

Evaluation of temperature-induced effects on safety-relevant properties of clay host rocks with regard to HLW/SF disposal

AbstractDBE TECHNOLOGY, BGR and GRS are developing a methodology to demonstrate the safety of a repository for high-level waste and spent fuel (HLW/SF) in clays according to the requirements of the German regulating body. In particular, these requirements prescribe that the barrier effect of host rocks must not be compromised by a thermal impact resulting from HLW/SF emplacement. To substantiate and quantify this requirement, we carried out a literature survey of research on thermally-induced changes on clay properties. Effects thus compiled can be divided into thermo-hydro-mechanical and chemical-biological-mineralogical effects and were analysed with regard to their relevance to the integrity of clay host rocks. This analysis identified one effect of major influence within each group: thermal expansion and compaction as well as results of microbial activities. Importantly, it further revealed that a moderate temperature increase above 100°C cannot be expected to compromise the integrity of the geological barrier according to the current knowledge state. Evidence is presented in this paper that temperature increases up to 150°C can actually contribute to an improved performance of a radioactive waste repository by increasing the consolidation of the clay and sterilizing the repository's near-field to depress the deteriorative microbial effects. A quantitative temperature criterion for thermal impact of HLW/SF on clay host rocks is accordingly proposed.

Accounting for adaptation in assessing impact of climatic variations on crop yields: an empirical study of Arizona

The goal of this paper is to analyze the impacts of climatic variation around current normals on crop yields and explore corresponding adaptation effects in Arizona, using a unique panel data. The empirical results suggest that both fertilizer use and irrigation are important adaptations to climate change in crop production. Fertilizer use has a positive impact on crop yields as expected. When accounting for irrigation and its interaction with temperature, a moderate temperature increase tends to be beneficial to both cotton and hay yields. The empirical model in this paper features with two methodological innovations, identifying the effects of temperature change conditional on adaptations and incorporating potential spatial spillover effects among input use.

A new NMR approach for structure determination of thermally unstable biflavanones and application to phytochemicals from Garcinia buchananii.

Previous activity-guided phytochemical studies on Garcinia buchananii stem bark, which is traditionally used in Africa to treat various gastrointestinal and metabolic illnesses, revealed xanthones, polyisoprenylated benzophenones, flavanone-C-glycosides, biflavonoids, and/or biflavanones as bioactive key molecules. Unequivocal structure elucidation of biflavonoids and biflavanones by means of NMR spectroscopy is often complicated by the hindered rotation of the monomers around the C-C axis (atropisomerism), resulting in a high spectral complexity. In order to facilitate an unrestricted rotation, NMR spectra are usually recorded at elevated temperatures, commonly over 80 °C, which effects in a single set of resonance signals. However, under these conditions, one of the target compounds of this investigation, (2R,3S,2″R,3″R)-manniflavanone (1), undergoes degradation. Therefore, we demonstrated in the present study that the 1,1-ADEQUATE could be successfully used as a powerful alternative approach to confirm the C-C connectivities in 1, avoiding detrimental conditions. However, a moderate increase in temperature up to 50 °C was sufficient to deliver sharp signals in the proton NMR experiment of (2R,3S,2″R,3″R)-isomanniflavanone (2) and (2″R,3″R)-preussianone (3). In addition, two new compounds could be isolated, namely (2R,3S,2″R,3″R)-GB-2 7″-O-β-D-glucopyranoside (4) and (2R,3S,2″R,3″R)-manniflavanone-7″-O-β-D-glucopyranoside (5), and whose structures were elucidated by spectroscopic analysis including 1D and 2D NMR and mass spectrometry methods. The absolute configurations were determined by a combination of NMR and electronic circular dichroism (ECD) spectroscopy. The aforementioned compounds exhibited high anti-oxidative capacity in the H2O2 scavenging, hydrophilic Trolox equivalent antioxidant capacity (H-TEAC) and hydrophilic oxygen radical absorbance capacity (H-ORAC) assays.

Size effects and temperature dependence on strain-hardening mechanisms in some face centered cubic materials

The mechanical behavior of face centered cubic metals is deeply affected when specimen dimensions decrease from a few millimeters to a few micrometers. At room temperature, a critical thickness (t) to grain size (d) ratio (t/d)c was previously highlighted, under which the softening of mechanical properties became very pronounced both in terms of Hall–Petch relation and work hardening mechanisms. In this work, new experimental results are provided concerning the influence of temperature on this size effect for copper, nickel and Ni–20wt.%Cr, representative of a wide range of deformation mechanisms (i.e. dislocation slip character). It is shown that multicrystalline samples (t/d<(t/d)c) are not deeply affected by an increase in temperature, independently of the planar or wavy character of dislocation glide. For pronounced wavy slip character metals, surface effects in polycrystals (t/d>(t/d)c) are not significant enough to reduce the gap between polycrystal and multicrystal mechanical behavior when the temperature increases. However, a transition from wavy slip to planar glide mechanisms induces a modification of the polycrystalline behavior which tends toward multicrystalline one with a moderate increase in temperature. This work demonstrates that surface effects and grain size influence can be successfully disassociated for the three studied materials using an analysis supported by the Kocks–Mecking formalism. All these results are supported by microscopic investigations of dislocation substructures and compared to numerical simulations using a strain gradient plasticity model.

Las Endometrosis Genitales. Consideraciones a propósito de 465 observaciones

Se hace una revisión de 465 casos de endometriosis perteneciente a la Clínica de Ginecología de Buenos Aires desde el año de 1928 a 1955. Tesis de 465 casos son 1,6% del número total de pacientes ginecológicas. 90,3% de estos materiales está constituido por endometriosis no asociado. Estos casos se han clasificado en grupos Varios: endometriosis mucosa 62% (uterina interna y la endometriosis tubárica). Serosa endometriosis (ovario y peritoneal): 27,4%, Otros, 10,6%. La endometriosis uterina interna constituye el grupo más importante, 47,5% de 911 el material. El autor es capaz de reconocer que macroscópicamente. Puede ser circunscrito o difuso. Es Posible confundirlos, mediante el examen macroscópico, con hiperplasia difusa y uterinos miomas. En 51 de los casos hubo una reacción a la estimulación hormonal. En 18 de los casos hubo hiperplasia de distinto grado. El mayor número de casos de ciclo bifásico normal tiene endometriosis uterina interna. Hay dos casos de endometriosis y el embarazo. Hay un caso en el que el paciente tenía de perforación a nivel de un foco de una endometriosis interna, durante el legrado después de un aborto. En 4 casos se observó la transformación maligna y en 3 de ellos coexistía con ACE, y en el cuarto caso fue exclusivo. Un caso en el que se observó degeneración sarcomatoso. Los siguientes son frecuentes asociados con la endometriosis uterina interna: Los miomas, 55%, hiperplasia del endometrio, 14% adenomas, 14,4%. Salpingitis, 9%, tumores de ovario, el 5,4%. El cáncer del cuello del útero, el 3,1%, el cáncer del endometrio, el 2,7%. Un aislado endometriosis uterina interna no es frecuente. Los síntomas más frecuentes encontradas son: dolor abdominal bajo, 70%, metrorragia en 16,6%. El autor sugiere y explicación de la hemorragia. El diagnóstico se presume en la mayoría de los casos. El X-Ray muy mala información. Los ensayos farmacodinámicos son de valor relativo. El tratamiento es quirúrgico conservador, a menos que otras asociaciones podrían Requiere otros procedimientos más amplios. En la endometriosis del ovario el hecho característico es el "quiste chocolated", y podría estar unido a las estructuras Alentour. Histológicamente fácil de reconocer cuando son pequeños, no por lo que cuando son muy grandes y viejos. Hay menos tejido conjuntivo alrededor de endometrio heterotópico. Sólo en el 43% de los casos las formas puras se ha encontrado. Otras asociaciones: mioma uterino, 4 casos. Los tumores de ovario, 6 casos. Los adenomas, 5. salpingitis, 7 casos. La hiperplasia del endometrio, 4. Cáncer de cuello uterino, 3. Las quejas importantes son: Dolor, 25% de los casos durante la menstruación. Historia de una crisis dolorosa acompañada de una irritación peritoneal. Aumento moderado de la temperatura, del 8,9%. Los síntomas de la compresión de las vísceras adjoing se han observado con menos frecuencia. Esterilidad en 8,7% de los casos. El diagnóstico es difícil, el proceso debe mantenerse en mente. El tratamiento es quirúrgico y medida de lo posible conservador. Hay 50 casos puros de la endometriosis tubárica. Formas intersticiales, 58%. Ístmica, 14%. Ampullar: 16%, 12% y localizada en la ampolla y porciones intersticiales. En ambos tubos, el 66%. Puede estar asociado con miomas uterinos, embarazo ectópico, cáncer de cuello uterino, tumores de ovario, etc. Por el diagnóstico de un examen microscópico se requiere, ya que puede ser confundido con el embarazo ectópico, endosalpingitis. La endometriosis tubárica es frecuente en la mujer menor de 40 años de edad, mientras que la endometriosis uterina es más frecuentes después de la de cuatro décadas de la vida. Esterilidad, el 62% de los casos. Aquellos localizada en la porción intersticial son asintomático. Dismenorrea, 4 casos. La forma ampullar da una sintomatología dolorosa. Cuanto más cerca están del orificio abdominal, más doloroso que se conviertan. El tratamiento conservador si es posible. Hubo 31 casos de endometriosis peritoneal, localizados especialmente en el Douglas. Síntomas: dismenorrea intermenstrual constante con es intenso, progresivo. Hipermenorrea. Sintomatología urinaria. El tratamiento es la resección parcial o en relación con las presentes condiciones. El autor describe 13 casos de perforación endometriosis vaginal fornical. Esta variedad, junto con endometriosis vesical y umbilical son accesible y fácilmente diagnosticados en. En 6 casos fue posible establecer la relación con la endometriosis ovárica. En todos ellos hubo una invasión del tabique rectovaginal. Ocurriendo más frecuentes entre treinta y cuarenta año de edad. En cuanto a la sintomatología, esto no es a diferencia de la de la enfermedad inflamatoria pélvica crónica, excepto que en muchos casos la dismenorrea severa está presente y que se hace referencia más frecuentes en el recto o región sacrococcígea. El tratamiento como medida de lo posible será conservador.

Sharp decline in counter-ion transport number of electrodialysis ion exchange membrane on moderate increase in temperature

The counter-ion transport-number of membrane affects columbic efficiency of electrochemical cells, many of which encounter varying salt concentration or temperature at different times of operation. Effect of NaCl concentration and temperature on the counter-ion transport number of commercial cation (Selemion CMV and Neosepta CMX) and anion (Selemion AMV and Neosepta AMX) exchange membranes was determined using chronopotentiometry. The transport number of the membranes didn't change with increasing NaCl concentration from 0.017M to 0.1M. Variation of transport number with temperature was determined from chronopotentiometric data using the Sand equation as well as a novel procedure. Values obtained from the Sand equation showed an anomalous trend, but the values obtained from the second procedure followed a consistent trend. The counter-ion transport number decreased significantly on increasing temperature by 20°C and the decline was higher for the cation exchange membranes.

Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes in biofilms by pulsed ultraviolet light.

BackgroundThe inactivation of biofilms formed by pathogenic bacteria on ready-to-eat and minimally processed fruits and vegetables by nonthermal processing methods is critical to ensure food safety. Pulsed ultraviolet (PUV) light has shown promise in the surface decontamination of liquid, powdered, and solid foods. In this study, the antimicrobial efficacy of PUV light treatment on nascent biofilms formed by Escherichia coli O157:H7 and Listeria monocytogenes on the surfaces of food packaging materials, such as low-density polyethylene (LDPE), and fresh produce, such as lettuce (Lactuca sativa) leaves, was investigated.ResultsThe formation of biofilms on Romaine lettuce leaves and LDPE films was confirmed by crystal violet and Alcian blue staining methods. Inactivation of cells in the biofilm was determined by standard plating procedures, and by a luminescence-based bacterial cell viability assay. Upon PUV treatment of 10 s at two different light source to sample distances (4.5 and 8.8 cm), viable cell counts of L. monocytogenes and E. coli O157:H7 in biofilms on the lettuce surface were reduced by 0.6–2.2 log CFU mL−1 and 1.1–3.8 log CFU mL−1, respectively. On the LDPE surface, the efficiency of inactivation of biofilm-encased cells was slightly higher. The maximum values for microbial reduction on LDPE were 2.7 log CFU mL−1 and 3.9 log CFU mL−1 for L. monocytogenes and E. coli O157:H7, respectively. Increasing the duration of PUV light exposure resulted in a significant (P < 0.05) reduction in biofilm formation by both organisms. The results also revealed that PUV treatment was more effective at reducing E. coli biofilms compared with Listeria biofilms. A moderate increase in temperature (~7–15°C) was observed for both test materials.ConclusionsPUV is an effective nonthermal intervention method for surface decontamination of E. coli O157:H7 and L. monocytogenes on fresh produce and packaging materials.

Sticking Probability and Reactivity of Hyperthermal O2 Molecules Impinging on CO Pre-covered Pd(100): Effect of Rotational States with K &gt; 1

Collisional alignment in the supersonic expansion of oxygen seeded in lighter carriers allows to produce rotationally aligned beams which were used to study the sticking probability, S, and the reactivity, \(P_{{co_{2} }}\), of helicoptering and cartwheeling O2 in the lowest rotational state impinging normally onto Pd(100). Molecules with different rotational alignment are thereby chosen by mechanically selecting either the slow or the fast speed tail of the beam velocity distribution. Here we show for O2 reacting with CO pre-covered Pd(100) that even a moderate increase in the nozzle temperature, TN, with respect to room temperature implies significant changes in both S and \(P_{{co_{2} }}\). Since TN affects mainly the rotational state distribution in the formed beam, we conclude that molecules in rotational states with K ≥ 3 behave very differently from those with K = 1. Data are presented for both small and intermediate CO pre-coverage.

Sensitivity of cold acclimation to elevated autumn temperature in field-grown Pinus strobus seedlings.

Climate change will increase autumn air temperature, while photoperiod decrease will remain unaffected. We assessed the effect of increased autumn air temperature on timing and development of cold acclimation and freezing resistance in Eastern white pine (EWP, Pinus strobus) under field conditions. For this purpose we simulated projected warmer temperatures for southern Ontario in a Temperature Free-Air-Controlled Enhancement (T-FACE) experiment and exposed EWP seedlings to ambient (Control) or elevated temperature (ET, +1.5°C/+3°C during day/night). Photosynthetic gas exchange, chlorophyll fluorescence, photoprotective pigments, leaf non-structural carbohydrates (NSC), and cold hardiness were assessed over two consecutive autumns. Nighttime temperature below 10°C and photoperiod below 12 h initiated downregulation of assimilation in both treatments. When temperature further decreased to 0°C and photoperiod became shorter than 10 h, downregulation of the light reactions and upregulation of photoprotective mechanisms occurred in both treatments. While ET seedlings did not delay the timing of the downregulation of assimilation, stomatal conductance in ET seedlings was decreased by 20–30% between August and early October. In both treatments leaf NSC composition changed considerably during autumn but differences between Control and ET seedlings were not significant. Similarly, development of freezing resistance was induced by exposure to low temperature during autumn, but the timing was not delayed in ET seedlings compared to Control seedlings. Our results indicate that EWP is most sensitive to temperature changes during October and November when downregulation of photosynthesis, enhancement of photoprotection, synthesis of cold-associated NSCs and development of freezing resistance occur. However, we also conclude that the timing of the development of freezing resistance in EWP seedlings is not affected by moderate temperature increases used in our field experiments.

Cognitive and perceptual responses during passive heat stress in younger and older adults.

We tested the hypothesis that attention, memory, and executive function are impaired to a greater extent in passively heat-stressed older adults than in passively heat-stressed younger adults. In a randomized, crossover design, 15 older (age: 69 ± 5 yr) and 14 younger (age: 30 ± 4 yr) healthy subjects underwent passive heat stress and time control trials. Cognitive tests (outcomes: accuracy and reaction time) from the CANTAB battery evaluated attention [rapid visual processing (RVP), choice reaction time (CRT)], memory [spatial span (SSP), pattern recognition memory (PRM)], and executive function [one touch stockings of Cambridge (OTS)]. Testing was undertaken on two occasions during each trial, at baseline and after internal temperature had increased by 1.0 ± 0.2°C or after a time control period. For tests that measured attention, reaction time during RVP and CRT was slower (P ≤ 0.01) in the older group. During heat stress, RVP reaction time improved (P < 0.01) in both groups. Heat stress had no effect (P ≥ 0.09) on RVP or CRT accuracy in either group. For tests that measured memory, accuracy on SSP and PRM was lower (P < 0.01) in the older group, but there was no effect of heat stress (P ≥ 0.14). For tests that measured executive function, overall, accuracy on OTS was lower, and reaction time was slower in the older group (P ≤ 0.05). Reaction time generally improved during heat stress, but there was no effect of heat stress on accuracy in either group. These data indicate that moderate increases in body temperature during passive heat stress do not differentially compromise cognitive function in younger and older adults.

Flow and heat transfer of non-Newtonian fluids in enameling dies

A widely used technique for the coating of magnet wires is passing them through enameling dies, from which they exit with a defined layer of enamel deposited on their surface. The generalized Couette flow, which emerges inside the converging annular gap between the moving wire and the stationary wall of the die, is computationally analyzed using the lubrication theory approximation. Non-Newtonian flow behavior and heat transfer are considered as well. The obtained results give a detailed insight into the effects of shear thinning/thickening on the velocity field and the wall shear stress along the wire. Despite the intense generation of viscous heat in the highly sheared region, the still moderate increase in temperature of the enamel does not pose any possible cooling problem. The influence of the die geometry on the drag force on the wire is examined by varying the axial contraction of the die, whose shape is assumed to follow a cosine-type function. The applied changes in the die geometry produce the same trends in the resulting drag force for all considered rheologies. The targeted reduction in the drag force could be achieved with the same die shape regardless of the flow behavior of the fluid. The predictions obtained from the lubrication theory based analytical model were validated against numerical results from computationally much costlier CFD simulations. This assessment proved the analytical model as a computationally efficient and reliable approach to describe the flow inside the die also for the fairly complex case of a shear thinning non-Newtonian fluid with temperature dependent viscosity.

Ocean warming-acidification synergism undermines dissolved organic matter assembly.

Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors—warming and acidification—threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow— even hinder—the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming–acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected.