Examining the relationship between climate change-related research output and CO2 emissions

Scientometrics - Climate change has been a pressing global issue in current times, which has seen many initiative programs set out to try and limit the rise in CO2 emissions globally. The main...     

Subharmonic emissions from microbubbles: effect of the driving pulse shape

The aims of this work are to investigate the response of the ultrasonic contrast agents (UCA) insonified by different arbitrary-shaped pulses at different acoustic pressures and concentration of the contrast agent focusing on subharmonic emission. A transmission setup was developed in order to insonify the contrast agent contained in a measurement chamber. The transmitted ultrasonic signals were generated by an arbitrary wave generator connected to a linear power amplifier able to drive a single-element transducer. The transmitted ultrasonic pulses that passed through the contrast agent-filled chamber were received by a second transducer or a hydrophone aligned with the first one. The radio frequency (RF) signals were acquired by fast echographic multiparameters multi-image novel apparatus (FEMMINA), which is an echographic platform able to acquire ultrasonic signals in a real-time modality. Three sets of ultrasonic signals were devised in order to evaluate subharmonic response of the contrast agent respect with sinusoidal burst signals used as reference pulses. A decreasing up to 30 dB in subharmonic response was detected for a Gaussian-shaped pulse; differences in subharmonic emission up to 21 dB were detected for a composite pulse (two-tone burst) for different acoustic pressures and concentrations. Results from this experimentation demonstrated that the transmitted pulse shape strongly affects subharmonic emission in spite of a second harmonic one. In particular, the smoothness of the initial portion of the shaped pulses can inhibit subharmonic generation from the contrast agents respect with a reference sinusoidal burst signal. It also was shown that subharmonic generation is influenced by the amplitude and the concentration of the contrast agent for each set of the shaped pulses. Subharmonic emissions that derive from a nonlinear mechanism involving nonlinear coupling among different oscillation modes are strongly affected by the shape of the ultrasonic driving pulse.     

表面活性剂对乳化液稳定性的影响

乳化液在带钢低温轧制过程中起到冷却,润滑,清洗及防锈作用,而乳化液的稳定性直接影响到其在冷轧过程中所起作用的大小。影响乳化液稳定性的因素很多,本文主要阐述表面活性剂对乳化液稳定性的影响,而这种影响因素在实际的生产过程中极易被忽视。     

Highly contrasting effects of different climate forcing agents on terrestrial ecosystem services

Many atmospheric constituents besides carbon dioxide (CO(2)) contribute to global warming, and it is common to compare their influence on climate in terms of radiative forcing, which measures their impact on the planetary energy budget. A number of recent studies have shown that many radiatively active constituents also have important impacts on the physiological functioning of ecosystems, and thus the 'ecosystem services' that humankind relies upon. CO(2) increases have most probably increased river runoff and had generally positive impacts on plant growth where nutrients are non-limiting, whereas increases in near-surface ozone (O(3)) are very detrimental to plant productivity. Atmospheric aerosols increase the fraction of surface diffuse light, which is beneficial for plant growth. To illustrate these differences, we present the impact on net primary productivity and runoff of higher CO(2), higher near-surface O(3), and lower sulphate aerosols, and for equivalent changes in radiative forcing. We compare this with the impact of climate change alone, arising, for example, from a physiologically inactive gas such as methane (CH(4)). For equivalent levels of change in radiative forcing, we show that the combined climate and physiological impacts of these individual agents vary markedly and in some cases actually differ in sign. This study highlights the need to develop more informative metrics of the impact of changing atmospheric constituents that go beyond simple radiative forcing.     

Comparing the effect of carbon-based nanofillers on the physical properties of flexible polyurethane foams

Flexible polyurethane foams filled with a fixed amount of carbon-based nanofillers, in particular multiwall nanotubes and graphenes, have been studied to clarify the influence of the morphology and functional groups on the physical properties of these polymeric foams. The effect of the carbon nanoparticles on the microphase separation has been analyzed by FT-IR spectroscopy revealing a decrease in the degree of phase separation of the segments. Variations of the glass transition temperature and an improved thermal stability were observed due to the presence of the nanoparticles. The EMI shielding effectiveness of flexible PU foams has also been enhanced, in particular for FGS nanocomposite foams.     

Modeling the effect of dispersed doping agents in carbon nanotubes

Theoretical studies of how the electronic properties of a nanotube are affected by one isolated doping agent is commonly done by ab-initio electronic structure calculations. Although these calculations are essential to understand how the system responds to doping, they are by no means sufficient, since, in reality, a large disordered array of doping agents must be considered. It is then necessary to combine ab-initio techniques with less-computationally-demanding methods if one wishes to describe the real effect of doping on the electronic properties of nanotubes. Here we propose a method that makes use of ab-initio results for single impurities as an input to generate the parameters of the less-demanding tight-binding technique. The method is based on suitable sum rules for the Green functions of the impurity-free nanotubes and does not rely on any fitting scheme. The resulting parametrization allows us to describe disordered systems without losing the important contributions due to charge transfer and screening. Transport properties are subsequentially investigated.     

晶核剂的选择对可切削玻璃陶瓷析晶性能的影响

对可切削玻璃陶瓷材料来讲,其内部云母微晶相的含量及云母晶体间交错程度的大小直接影响材料的性能.本文采用添加不同的晶核剂的方法,通过差热分析(DTA)、扫描电镜(SEM)及X射线衍射(XRD)测试分析,研究了晶核剂对可切削玻璃陶瓷析晶性能的影响.研究表明同时采用F和Ti作为晶核剂时,材料内部的晶相含量明显提高,并且材料的可切削性能也得到了改善.     

The effect of viscosity modifying agents on mortar and concrete

The influence of different viscosity modifying agents (VMA) on the flow properties and the rheology of self-compacting mortars is studied. Additionally, their effect on the early hydration of cement pastes and on the development of concrete strength is determined. Beside the inorganic VMA microsilica (MS) and nanosilica slurry (NS) organic VMA based on high molecular ethylenoxide derivate (EO), natural polysaccharide (PS) and starch derivate (ST) are used. The different VMA are combined with a superplasticizer (SP).At constant water-to-binder ratio (w/b) the addition of VMA causes a decrease of mortar flow and an increase of flow time (V-funnel test). At the same time yield stress and plastic viscosity are increased. At a constant dosage of superplasticizer (SP) mixtures with VMA require a higher w/b to keep the same flow properties as the reference mixtures without VMA. In spite of the higher w/b flow time and plastic viscosity respectively are only slightly reduced. This property is especially beneficial for the production of stabilizer-type self-compacting concrete where the amount of fines can be reduced with the use of VMA. However, only the use of VMA PS and ST leads to smaller changes of flow when w/b is changed. The organic VMA show almost no influence on early cement hydration and the development of compressive strength. However, the inorganic VMA cause an acceleration of hydration and higher compressive strength at the age of 1 day.     

The effect of chelating agents on the cathodic polarization and the electrodeposition of iron powders

The electrodeposition of iron powders from different baths containing the same major chemical constitutents was studied. The baths were mainly based on aqueous dilute solutions of ferrous sulphate and additives such as oxalic and citric ions. The effect of these additives on the cathodic polarization curves, current efficiency and powder morphology of the electrodeposited iron powders was investigated. It was found that electrodeposition systems with chelating agents were more polarized than a non-chelated system and produced finer powders with no dendrites.     

The effect of antibacterial agents on the behaviour of cultured mammalian fibroblasts

Wound infections retard healing rates and can lengthen the time a patient is required to spend in hospital. Obviously it is desirable to minimize or remove pathogenic organisms to allow wound healing to progress optimally. At present there are a large range of topical applications available in the form of antibiotics or antiseptics, but the toxic effects of these agents may outweight the benefits. In this study two conventional antiseptic agents were examined together with a range of phosphate-based glasses which were designed to release metal ions into an aqueous environment. As a control a series of standard metal ion solutions were prepared and examined in the same test system. The metal ions examined are considered important in the wound healing environment either for their potential bacteriostatic effects or indeed their potential for increasing cellular activity. This part of the study examined the effects of these agents on mammalian cells in vitro, using a standard MTT assay to assess the cytotoxicity or activity of cultured mouse fibroblasts. It was found that chlorhexidene, a commonly used antiseptic agent, was toxic at low levels. The controlled release glasses, in most cases, increased the rate of cell activity before reaching toxic levels. This effect was also found with the standard metal solutions.     

Modeling short- and long-term time-dependent nonlinear behavior of polyethylene

A new methodology for developing macromechanical constitutive formulations for time-dependent materials is presented in this article. In particular, two phenomenological constitutive models for polymer materials are illustrated, describing time-dependent and nonlinear mechanical behavior. In this new approach, short-term creep test data are used for modeling both short-term and long-term responses. The differential form of a model is used to simulate typical nonlinear viscoelastic polymeric behavior using a combination of springs and dashpots. Unified plasticity theory is then used to develop the second model, which is a nonlinear viscoplastic one. Least squares fitting is applied for the determination of material parameters for both models, based on experimental results. Due to practical constraints, experimental data are usually available for short-term time-frames. In the presented proposed formulation, the material parameters determined from short-term testing are used to obtain material parameter relationships for predicting the long-term material response. This is done by extending short-term information for longer time frames. Finally, theoretical and experimental results of tensile tests on polyethylene subjected to various load levels and test times are compared and discussed. Very good agreement of the modeling results with experimental data shows that the developed formulation provides a flexible and reliable framework for predicting load responses of polymers.     

The effect of process parameters on audible acoustic emissions from high-shear granulation

Product quality in high-shear granulation is easily compromised by minor changes in raw material properties or process conditions. It is desired to develop a process analytical technology (PAT) that can monitor the process in real-time and provide feedback for quality control. In this work, the application of audible acoustic emissions (AAEs) as a PAT tool was investigated. A condenser microphone was placed at the top of the air exhaust on a PMA-10 high-shear granulator to collect AAEs for a design of experiment (DOE) varying impeller speed, total binder volume and spray rate. The results showed the 10 Hz total power spectral densities (TPSDs) between 20 and 250 Hz were significantly affected by the changes in process conditions. Impeller speed and spray rate were shown to have statistically significant effects on granulation wetting, and impeller speed and total binder volume were significant in terms of process end-point. The DOE results were confirmed by a multivariate PLS model of the TPSDs. The scores plot showed separation based on impeller speed in the first component and spray rate in the second component. The findings support the use of AAEs to monitor changes in process conditions in real-time and achieve consistent product quality.     

Blending effect of sucrose and surfactant templating agents on silica mesostructure

We report the blending effect of surfactant and sucrose as a nonsurfactant templating agent on the silica mesostructure. The CTAB/sucrose-templated mesoporous silica (SCS) was compared with CTAB-templated MCM-41. The MCM-41 showed spherical morphology with a particle diameter of 1.1–1.5 μm, and gave a bimodal size distribution, centered at 2.1 nm and 8.9 nm, which is assigned to hexagonally-arrayed cylindrical pores and interparticle-pores between small MCM-41 clusters, respectively. SCS gave unique and extraordinary morphology in which two different mesostructures have grown with both of them facing each other. The ordered MCM-41 pore structure clung to silica nanosphere-framed wormlike mesostructure, resulting in a bimodal pore size distribution centered at 2.1 nm and 7.0 nm. It was revealed that both of CTAB and sucrose act independently as a surfactant and a nonsurfactant template.     

The effect of capping agents on the structural and magnetic properties of cobalt ferrite nanoparticles

Microwave-assisted co-precipitation method was adopted to analyze the effect of polyethylene glycol (PEG) and urea concentrations on the properties of cobalt ferrite nanoparticles (NPs). The average crystallite size of single phase cubic spinel cobalt ferrite NPs was controlled within 10–14 nm with the effect of PEG, urea and the combination of them. The transmission electron micrographs revealed that the morphology of cobalt ferrites was not significantly influenced by the different concentration of capping agents but almost uniform morphology with nearly narrow size distribution was obtained. The interaction of PEG and urea molecules on the surface of nanoparticles was mediated through –OH hydroxyl group affected the crystal growth rate. The possible interaction mechanism was proposed with the help of IR vibrational spectra. All the samples exhibited ferromagnetism at room temperature and it was found that the capping agents showed an effect on the magnetic properties. The maximum saturation magnetization of 58 emu/g was achieved when the urea of 60 mg was used and the maximum coercivity of 311 Oe was attained when the mixture of PEG (40 mg) and urea (20 mg) were used. Ultrafine and hydrophilic cobalt ferrite NPs that showed appreciable magnetic properties obtained in the present experimental procedure would be of great interest in various biomedical applications.     

Influence of memory effect caused by aged bag filters on the stack PCDD/F emissions

To our best knowledge, this study is the first research which investigates whether the PCDD/F memory effect could also be caused by bag filters. In this study, the PCDD/F characteristics of the flue gases in front of and behind the bag filters of one municipal solid waste incinerator (MSWI) and two electric arc furnaces (EAFs) were investigated to clarify the memory effect of PCDD/Fs and their influence on emissions. After the bag filters were operated for over four years, the PCDD/F concentrations in the stack flue gases were all higher than those prior to the aged bag filter, rendering a negative PCDD/F removal. This memory effect is because gaseous phase PCDD/Fs are released from the contaminated filters of the aged bag filters. The release of 2,3,7,8-TeCDF, 1,2,3,7,8-PeCDF and 2,3,4,7,8-PeCDF from the contaminated filters of the EAFs increased the PCDD/F concentration and their fractions in the stack flue gases. In contrast, the MSWI exhibited increasing fractions of 1,2,3,4,6,7,8-HpCDD, OCDD after flue gases passed through its aged bag filter. The activated carbon of the MSWI adsorbed more lower chlorinated-substituted PCDD/Fs in the raw flue gases, and the remaining higher chlorinated congeners gradually accumulated on the aged filters, and were released in lower PCDD/F concentration conditions.     

Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector–parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46–77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.     

Comparing the scatter of citing and cited literature

Using the subjects desalination and educational psychology, the scatter of periodical articles over periodical titles was compared at two levels, the second level being a random sample of periodical articles cited by the first level. Several measures were used to compare the extent of scatter at the two levels. Some methods commonly used in bibliometrics produced conflicting evidence on whether the citing literature (first-level) or the cited (second-level) was more scattered. A computer-intensive sampling procedure, known as the Bootstrap method, was then used to estimate the scatter of the total cited population from the scatter of the empirical sample. Cumulative distributions were prepared to show what percentage of periodicals accounted for various percentages of articles at each level of scatter. Only at the 90th percentile of articles did the percentage of periodical titles in the cited literature significantly exceed that of the citing literature. At the tail-end of the Bradford-type distribution, the cited literature appears to be more scattered than the literature citing it.     

The effect of climate on fractures and deaths due to falls among white women

Climatic conditions may affect the incidence of fractures and fall deaths. Analysis of national fatality data shows that among white women, those living in colder climates have higher rates of fall deaths. Fall deaths increase in winter in all regions, but especially so in colder states. In a prospective cohort study of 96,506 predominantly white female nurses 35-59 years of age, we found that, after controlling for personal and lifestyle characteristics, those women residing in colder climate also had a higher incidence of hip and forearm fracture. In colder states, fracture rates were substantially higher in winter than in summer. A cold climate appears to be a significant risk factor for both fractures and fall deaths among white women, particularly as they age.