Transport on flexible Rydberg aggregates using circular states

Assemblies of interacting Rydberg atoms show promise for the quantum simulation of transport phenomena, quantum chemistry and condensed matter systems. Such schemes are typically limited by the finite lifetime of Rydberg states. Circular Rydberg states have the longest lifetimes among Rydberg states but lack the energetic isolation in the spectrum characteristic of low angular momentum states. The latter is required to obtain simple transport models with few electronic states per atom. Simple models can however even be realized with circular states, by exploiting dipole-dipole selection rules or external fields. We show here that this approach can be particularly fruitful for scenarios where quantum transport is coupled to atomic motion, in adiabatic excitation transport or quantum simulations of electron-phonon coupling in light harvesting. Additionally, we explore practical limitations of flexible Rydberg aggregates with circular states and to which extent interactions among circular Rydberg atoms can be described using classical models.Comment: 9 Pages, 5 Figure

Vertical annular gas–liquid two-phase flow in large diameter pipes

Gas–liquid annular two phase flow in pipes is important in the oil and gas, nuclear and the process industries. It has been identified as one of the most frequently encountered flow regimes and many models (empirical and theoretical) for the film flow and droplet behaviour for example have been developed since the 1950s. However, the behaviour in large pipes (those with diameter greater than 100 mm) has not been fully explored. As a result, the two- phase flow characteristics, data, and models specifically for such pipes are scarce or non-existent such that those from smaller pipes are extrapolated for use in design and operation. Many authors have cautioned against this approach since multiphase pipe flow behaviour is different between small and large pipes. For instance the typical slug flows seem not to occur in vertical upwards flows when the pipe diameter exceeds 100 mm. It is therefore imperative that theoretical models and empirical correlations for such large diameter pipes are specifically developed. ...[cont.

Interfacial shear in adiabatic downward gas/liquid co-current annular flow in pipes

Interfacial friction is one of the key variables for predicting annular two-phase flow behaviours in vertical pipes. In order to develop an improved correlation for interfacial friction factor in downward co-current annular flow, the pressure gradient, film thickness and film velocity data were generated from experiments carried out on Cranfield University’s Serpent Rig, an air/water two-phase vertical flow loop of 101.6 mm internal diameter. The air and water superficial velocity ranges used are 1.42–28.87 and 0.1–1.0 m/s respectively. These correspond to Reynolds number values of 8400–187,000 and 11,000–113,000 respectively. The correlation takes into account the effect of pipe diameter by using the interfacial shear data together with dimensionless liquid film thicknesses related to different pipe sizes ranging from 10 to 101.6 mm, including those from published sources by numerous investigators. It is shown that the predictions of this new correlation outperform those from previously reported studies

Corporate incentives for obtaining higher level of carbon assurance: seeking legitimacy or improving performance?

Purpose - With the growing attention around carbon emissions disclosure, the demand for external carbon assurance on emissions reports has been increasing by stakeholders as it provides additional credibility and confidence. This study investigates the association between the higher level of external carbon assurance and improvement in a firm's carbon emissions. It provides an understanding of corporate incentives for obtaining a higher level of carbon assurance, particularly in relation to carbon performance enhancements. Design/methodology/approach - Data are collected from 170 US companies for the period 2012-2017, and are analysed using a change analysis. Generalized method of moment (GMM) is used to address endogeneity. Findings - Following the rationales taken by legitimacy and ‘outside-in’ management views, our findings reveal that a higher level of carbon assurance (i.e. reasonable assurance) marginally improves firms’ carbon performance (i.e. reported carbon emissions). This is consistent with ‘outside-in’ management view suggesting that a higher level of assurance could be utilised as a tool for accessing more information about stakeholders’ needs and concerns, which can be useful in enhancing carbon performance. Research limitations/implications - Our findings are generalizable to US firms and may not extend to other contexts. Practical implication – The implication of this study for companies is that a high level of sustainability assurance is a useful tool to access detailed information about stakeholder concerns, of which internalisation can help to marginally improve carbon performance. For policymakers, the insights into and enhanced understanding of the incentives for obtaining carbon assurance can help policymakers to develop effective policies and initiatives for carbon assurance. Considering the possible improvements in carbon performance when obtaining a high level of sustainability verification, governments need to consider mandating carbon assurance. Originality/value – This study extends the existing studies of assurance in sustainability context as well as in carbon context by explaining why companies voluntarily get expensive external verification (i.e. higher level of assurance) of their carbon emissions disclosure. This study responds to calls in the literature for empirical research investigating the association between environmental performance and external assurance with a focus on level of assurance

Gas/liquid flow behaviours in a downward section of large diameter vertical serpentine pipes

An experimental study on air/water flow behaviours in a 101.6 mm i.d. vertical pipe with a serpentine configuration is presented. The experiments are conducted for superficial gas and liquid velocities ranging from 0.15 to 30 m/s and 0.07 to 1.5 m/s, respectively. The bend effects on the flow behaviours are significantly reduced when the flow reaches an axial distance of 30 pipe diameters or more from the upstream bend. The mean film thickness data from this study has been used to compare with the predicted data using several falling film correlations and theoretical models. It was observed that the large pipe data exhibits different tendencies and this manifests in the difference in slope when the dimensionless film thickness is plotted as a power law function of the liquid film Reynolds number

Antimicrobial susceptibility pattern of Aeromonas hydrophila among patients presented with diarrhea attending two teaching hospitals in northern, Nigeria

A total of one hundred and twenty eight (128) stool samples were collected from patients attending Ahmadu Bello University Teaching Hospital Zaria and Aminu Kano Teaching Hospital Kano, and screened for the presence of Aeromonas hydrophila infection. Out of the one hundred and twenty eight samples analyzed 4 (3.12%) were found positive for Aeromonas hydrophila infection. Antibioticsusceptibility testing of Aeromonas hydrophila isolated showed that all the 4 (100%) isolates were sensitive to Colistin and Ceftazidime, 3 (75%) to Augmentin and 2(50%) to Gentamicin and Cefuroxine. All the isolates (100%) were however resistant to Cotrimoxazole, Tetracycline, Sulphatriad, Streptomycin, Cephalothin and Ampicilin. This study confirmed that Aeromonas hydrophila as a sole enteropathogen could be responsible for diarrhea and should be considered amongst the causative agents of diarrhea. Key words: Aeromonas, diarrhoea, antibiotic, susceptibility testing, ABUTH, AKTH

Role of Prebiotic, Probiotic and Symbiotic Diets on Bacterial proliferation in Feed and Intestine of African (Clarias gariepinus) Catfish

The influence of prebiotic, probiotic and symbiotic diet on microbial proliferation was studied using an in vitro method. In the present trial, formulated diets were supplemented with prebiotic (Sargassum muticum), probiotic (Parkia biglobosa) and combination of Parkia biglobosa and Sargassum muticum (symbiotic diet). Bacteria proliferation in supplemented feeds, small and large intestine of the African catfish, Clarias gariepinus fed the formulated diets were evaluated. The feeding trial that lasted 12 weeks was conducted in plastic aquaria, with each treatment replicated three times. A control diet containing only the feed ingredients was also formulated and fed for the same period. The result showed bacteria proliferation was lowest in the control diet and highest in feed supplemented with prebiotic. Low bacteria proliferation was observed in the small intestine of fish fed symbiotic diet while highest proliferation was recorded in the fish fed prebiotic diet. The result also revealed the lowest bacteria proliferation in the large intestine of fish fed symbiotic diet and highest in fish fed probiotic diet. Using the cell morphology and biochemical characteristics of bacteria isolates in supplemented feed, Clarias gariepinus small and large intestine, the result indicated the presence of some Lactic Acid Bacteria (LAB) known to produce a variety of antimicrobial substances which are able to stop the development of foodborne diseases by inhibiting the growth of food spoilage and pathogenic organisms

In vitro regeneration of hybrid plantlets of cashew (Anacardium occidentale l) through embryo culture

Embryos from immature nuts of cashew (Anacardium occidentale L.) were cultured in vitro to regenerate improved hybrid plantlets. Explants (embryo) were excised from developing F1 hybrid immature nuts derived from diallel cross and harvested at 2-, 4-, 6- and 8-weeks after pollination (WAPo) for in vitro culture. The explants were surface sterilized, aseptically dissected and cultured into pure basal Murashige and Skoog (MS) agar medium and MS medium supplemented with 1 mM each of naphthaleneacetic acid (NAA), benzyladenine (BA) and gibberellic acid (GA3) and subsequently observed for germination and survival rates until successful ones were transferred to the field. Age of explants was found to significantly influence both the germination and survival rates. Explants of 6 weeks old and above were found to give better germination rate and highest survival percentage in this study. Only MS medium supplemented with 1 mM of gibberellic acid (MS+GA3) supported germination and growth at 2-WAPo, suggesting the essentiality of GA3 as a growth regulator to a very young cashew embryo. Analysis also showed that factors such as medium composition, age of embryo and genotype (accession) significantly influence the germination rate of cashew embryo. It was observed that cashew embryos were found to be autonomy of growth regulator as the age increases and medium composition is only critical at very young age of the embryo. Successful germinated explants simultaneously produced shoot and root and were ready for transfer to field and acclimatization, between 90 and 112 days after inoculation.African Journal of Biotechnology Vol. 4 (6), pp. 548-553, 200

Offshore Topside Rotating Packed Bed as Process Intensified Alternative for Natural Gas Sweetening and Dehydration

This work is aimed at investigating the benefits of replacing conventional process unit operations with process intensified ones in offshore applications. This ensures that better use is made of raw materials, lower energy consumption and a reduced plant volume was achieved. Specifically, a rotating packed bed technology has been used for gas dehydration and sweetening. To achieve the aim of this study, a process intensification approach is used to redesign mature absorption processes to more compact and efficient one. Process simulation using Aspen Hysys was carried out for Triethylene glycol dehydration and monoethanolamine sweetening. More than 36-fold absorption unit size reduction was achieved thereby effecting large decrease in capital and operating costs compared to the conventional packed columns currently utilized in the offshore oil and gas industry. The process intensified technologies therefore can be deployed for offshore applications where space and size considerations are of utmost importance

Development of a Pseudo-Closed Loop Solar Collector Sun Tracking System with Optimized Set-Point Paths for Flat Plate Payload

This paper provides the theoretical framework for the development of a pseudo-closed loop solar tracking system incorporating a microcontroller for a flat payload, where the outputs of the system (the slope and the azimuth angles of the payload) are observed and the set-points for the system are to be optimally computed by the microcontroller. It also presents, from literature, the equations and models solar angles and incident angles for the development of the optimum set point path for the tracking, and gives the outline of the signal flow plan, as well as the corresponding flowchart, for the tracking system’s components interaction. The concept would provide a cheaper and simpler alternative to dual axis solar tracking incorporating solar sensors. The models presented here are adaptable to any geographical location in Nigeria and globally