One-photon excited luminescence of single gold particles diffusing in solution under pulsed illumination

Here we report on the visible luminescence of single gold nanospherical particles diffusing in water excited by a pulsed-laser at 488 nm. The signal studied by fluorescence correlation spectroscopy does not display the expected characteristics. The main deviation is obtained for the diffusion time that depends on the laser irradiance. Additional advanced methods of measurements have been implemented to further characterize the emission. These methods have allowed us to demonstrate that the luminescence does not blink even in the picosecond domain and that it does not photobleach either. The comparison between the signals obtained under pulsed and continuous excitations at the same wavelength suggests that the increase in the particle temperature plays a role in the non-linear increase in the luminescence intensity with the excitation power. As in the case of two-photon excited luminescence, it implies that a model describing the luminescence process for a single particle diffusing in liquid must take into account the whole system composed of the gold particle, the capping ligands and the surrounding water

Time-of-Flight Photon Spectroscopy: A Simple Scheme To Monitor Simultaneously Spectral and Temporal Fluctuations of Emission on Single Nanoparticles

Here we report on a novel scheme for spectral analysis that exploits the wavelength dependence of the time-of-flight of a photon in a dispersive medium. This versatile and cost-effective method, named time-of-flight photon spectroscopy (TOFPS), has the major advantage of being compatible with time-correlated single-photon counting experiments. Consequently, each photon acquired during an experiment is characterized by two parameters, its absolute time of arrival and its color, respectively. As a result, the spectral and temporal fluctuations of the emission of a single nano-object can be derived from a single measurement. As a proof of the concept, we demonstrate in the paper that the method can be used to perform Raman spectroscopy as well as fluorescence spectroscopy. We emphasize that TOFPS proves to be very efficient for improving signal-to-noise ratio in fluorescence correlation spectroscopy measurements by subsequent spectral filtering and to record luminescence spectra from single metallic particles. We demonstrate that the opportunity of simultaneously recording spectral and temporal fluctuations could be used to sort particles of different shapes inside a sample. TOFPS furthermore allows developing a new type of time interval distribution analysis which correlates the time interval between two photons and their corresponding color shift. It is applied to the analysis of the two-photon excited luminescence of a single gold nanorod. This method has a potential for a broad range of applications, among which time-resolved SERS spectroscopy and analysis of the dynamics of emission processes can be handled with new statistical approaches based on the correlation of spectral and temporal fluctuations

The dew points of acidic vapours in simulated power station flue gases

During combustion, sulphur and chlorine, which are present as the major impurities in fuel oil and coal, are partially converted into sulphuric acid and hydrochloric acid respectively. Condensation of such corrosive products is clearly highly undesirable and regions of plant have been identified where acid dewpoint corrosion impinges upon the efficiency and maintenance cost of oil and coal fired power stations. It is further recognised that prevention of acid deposition can be achieved if the flue gas temperature is maintained above the acid dewpoint. However, expulsion of flue gas at temperatures higher than the acid dew point decreases the energy yield from the fuel and is therefore wasteful and uneconomic. Clearly, precise determination of the acid dewpoint is vital. A literature survey showed that dewpoint data for the H₂SO₄/H₂O system have considerable scatter within a range ± 10K. Recently, Halstead and Talbot (CERLLeatherhead) have developed an equilibrium gas saturation technique which gives an uncertainty of only ±2K. There remains however some doubt about the estimate of the enthalpy of vaporisation of sulphuric acid. Furthermore little is known about the potentially more interesting three component system H₂SO₄/HCI/H₂O. This work has sought to tackle these deficiencies by applying an improved version of Halstead and Talbot's transpiration apparatus to dewpoint investigations in the H₂SO₄/H₂O system and to the H₂SO₄/HCI/H₂O system. The results obtained essentially confirm Halstead and Talbot's findings in the H₂SO₄/H₂O system and enabled a more precise determination of the vaporisation enthalpy of sulphuric acid. Very importantly, it has been established that the dewpoint is independent of the presence of HCl

On the occurrence of Acanthaster planci (the crown-of-thorns) at Minicoy Atoll.

The predation of coral-polyps by the multi-armed star fish Acanthaster planci is identified during the last two decades as a major biological factor that causes large scale death to reef corals at several parts of the Indo-Pacific. During a recent visit by a team of scientists from Central Marine Fisheries Research Institute,the presence of this star fish in the lagoon of Minicoy Atoll was noticed in November, 1979.Many control measures of star fishes have been practised elsewhere in the Pacific. However, hand-picking of the adults with the aid of pointed spears and killing them with formalin or ammonia solution is the most eifective.Careful search among the corals is required, since the crown-of-thorns hide under the crevices during day time

Predictive Accuracy of Fatty Liver Index Against Ultrasonography Among Overweight Non-Diabetic Patients Of A Tertiary Care Center In Tamil Nadu, South India

Introduction: The increasing prevalence of both obesity and type 2 diabetes due to easy access to high calorie foods and sedentary lifestyles resulted in NAFLD to be one of the ,major public health concern in India. Due to the asymptomatic nature of NAFLD, imaging techniques like ultrasonography and CT scan have been used as diagnostic tool though liver biopsy is gold standard test. Inspire of this, non-invasive algorithms like fatty liver index have been used nowadays in clinical as well as community to detect fatty liver. The current study aimed to determine the diagnostic accuracy among overweight non-diabetic patients.Methods: An observational cross sectional study was conducted in a internal medicine department of tertiary care center situated in South India between 2022 to 2023 .Convenient sampling technique was followed. A structured questionnaire was used to collect data on socio-demographic and relevant clinical details. Fatty liver index was enumerated with waist circumference, Body Mass Index, serum triglycerides and gamma glutaryl transferase. Ultrasonography was performed as diagnostic test. Results: A total of 107 study subjects were included. Majority of the study subjects were in age category of 40-60 years (66%). Both male and female genders were equal in number. The prevalence of non alcoholic fatty liver disease identified by fatty liver index was 57 % whereas by ultrasonography it was 54.2%. The sensitivity and specificity of fatty liver index validated against ultrasonography were 77.1% and 76.1% respectively. Conclusion: Fatty liver index has been found to be acceptable diagnostic tool which could be used especially when imaging techniques are not available

Crumpled sheet like graphene based WO3-Fe2O3 nanocomposites for enhanced charge transfer and solar photocatalysts for environmental remediation

The combination of two or more metal oxides onto graphene sheets with even distribution is projected to enhanced charge transfer properties in photocatalytic applications. We report, tungsten oxide (WO3) with iron oxide (Fe2O3) nanoparticles grown on graphene sheets via a facile economical one pot hydrothermal method and consequently characterized by standard analytical techniques. Synthesized Fe2O3 with WO3 nanoparticles were well ornamented on surface of the graphene sheets which have a significant charge transfer properties. The resulting hybrid WO3-Fe2O3-rGO (WFG) nanocomposites showed enhanced photocatalytic, heavy metal removal and antibacterial activities. The superior photocatalytic removal efficiencies were observed for the removal of rhodamine B (∼94%) and methylene blue dyes (∼98%) under solar light irradiation. The antibacterial activity of WFG nanocomposites were performed against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) as models for Gram-negative and Gram-positive bacteria. The outcome of the results have an intellectual effect on the use of WFG nanocomposites to address the upcoming energy and environment issues

All My Animals Are Equal, but None Can Survive without the Horse’. The Contribution of Working Equids to the Livelihoods of Women across Six Communities in the Chimaltenango Region of Guatemala

SIMPLE SUMMARY: Working equids are often absent from higher level policy interventions, and the global standard of their welfare is low. Understanding the social and cultural context of their contributions to human livelihoods generates evidence supporting the importance of their inclusion in livestock welfare programmes. Although there is increasing evidence globally that working equids contribute to women’s livelihoods and that women facilitate equid welfare, there is a well recognised gender gap in access to extension services. This study aims to investigate how working equids contribute to women’s livelihoods in six communities in Guatemala, using information from 34 face-to-face interviews. Results show that working equids support women’s livelihoods by generating income, saving time, feeding livestock and reducing domestic drudgery. Thirty-two women played a major role in the daily husbandry of working equids, and 31 expressed an interest in gaining more knowledge in equid care. This study explores the relationship between working equids and women in a local context, using the concept of ‘One Welfare’, and investigates the knowledge gaps that exist in the daily husbandry of horses, donkeys and mules. It emphasises the need for equid welfare organisations to understand women’s roles in their target communities and recognise what prevents women from accessing educational resources. ABSTRACT: It is widely assumed that working equid husbandry is carried out by men, and women are often not recognised as facilitating equid welfare. The aim of this study is to investigate how working equids contribute to women’s livelihoods in six of the World Horse Welfare programme target communities in Guatemala and determine what roles women have in their care. Thirty-four face-to-face interviews were carried out and data were analysed using both quantitative and qualitative methods. This study found that working equids support women by reducing domestic drudgery, generating income, feeding livestock and saving time. Thirty-two women played a major role in the care of one or more equids, and overall, women did not feel that they knew enough about equid husbandry. Thirty-one women said they would attend training opportunities if the advertising was clear and they felt that women were able to join. This study recognises the contribution of working equids to women’s livelihoods, describes the roles women play in equid husbandry and addresses the discrepancies between women’s roles and their capacity to undertake these tasks. This emphasises the need for extension services to include and cater for women, improving equid welfare and their ability to continue supporting women’s livelihoods

Influence of polarization and wavelength on two-photon excited luminescence of single gold nanospheres

The Brownian rotation of a nearly spherical gold particle capped with ligands can be observed in the correlation profile of the intensity of the two-photon excited luminescence. Here we report on a multi-parameter study of the luminescence properties, including spectral and polarization analysis of the signal at the single particle level. First, the data confirm the role of the radiative de-excitation of the surface plasmons in the luminescence process. Secondly, the results obtained at low power indicate that the capped particle in water can be approximatively described as a spherical rotor acting in the far-field as a point-like absorption and emission dipole of fixed directions. In addition, we show that the dynamics of the ligands, induced by the heat transfer from the particle to its environment, can be partly controlled by the choice of excitation wavelength

Even obligate symbioses show signs of ecological contingency: Impacts of symbiosis for an invasive stinkbug are mediated by host plant context

Many species interactions are dependent on environmental context, yet the benefits of obligate, mutualistic microbial symbioses to their hosts are typically assumed to be universal across environments. We directly tested this assumption, focusing on the symbiosis between the sap‐feeding insect Megacopta cribraria and its primary bacterial symbiont Candidatus Ishikawaella capsulata. We assessed host development time, survival, and body size in the presence and absence of the symbiont on two alternative host plants and in the insects\u27 new invasive range. We found that association with the symbiont was critical for host survival to adulthood when reared on either host plant, with few individuals surviving in the absence of symbiosis. Developmental differences between hosts with and without microbial symbionts, however, were mediated by the host plants on which the insects were reared. Our results support the hypothesis that benefits associated with this host–microbe interaction are environmentally contingent, though given that few individuals survive to adulthood without their symbionts, this may have minimal impact on ecological dynamics and current evolutionary trajectories of these partners

Prevalence Of Insulin Resistance and Its Correlation with Fatty Liver Index In Overweight Non-Diabetic Patients

Introduction: The increasing prevalence of both obesity and type 2 diabetes due to easy access to high calorie foods and sedentary lifestyles resulted in NAFLD to be one of the ,major public health concern in India. Due to the asymptomatic nature of NAFLD, imaging techniques like ultrasonography and CT scan have been used as diagnostic tool though liver biopsy is gold standard test. Inspire of this, non-invasive algorithms like fatty liver index have been used nowadays in clinical as well as community to detect fatty liver. The current study aimed to determine the diagnostic accuracy among overweight non-diabetic patients.Methods: An observational cross sectional study was conducted in a internal medicine department of tertiary care center situated in South India between 2022 to 2023 .Convenient sampling technique was followed. A structured questionnaire was used to collect data on socio-demographic and relevant clinical details. Fatty liver index was enumerated with waist circumference, Body Mass Index, serum triglycerides and gamma glutaryl transferase. Ultrasonography was performed as diagnostic test. Results: A total of 107 study subjects were included. Majority of the study subjects were in age category of 40-60 years (66%). Both male and female genders were equal in number. The prevalence of non alcoholic fatty liver disease identified by fatty liver index was 57 % whereas by ultrasonography it was 54.2%. The sensitivity and specificity of fatty liver index validated against ultrasonography were 77.1% and 76.1% respectively. Conclusion: Fatty liver index has been found to be acceptable diagnostic tool which could be used especially when imaging techniques are not available