BACKGROUND:"Laparoscopist's thumb," or thenar paresthesia, can result from prolonged or excessive grip force during laparoscopy, as can more general syndromes, such as carpal tunnel syndrome. This is particularly relevant in gynecology, where laparoscopic procedures are standard. Although this method of injury is well known, there is a paucity of data to guide surgeons in selecting more efficient, ergonomic instruments.OBJECTIVE:This study compared the ratio of applied tissue force and required surgeon input in a sample of common ratcheting laparoscopic graspers in a small-handed surgeon, to provide potential metrics applicable to surgical ergonomics and surgeon instrument choice.STUDY DESIGN:Laparoscopic graspers with varied ratcheting mechanisms and tip shapes were evaluated. Brands included Snowden-Pencer, Covidien, Aesculap, and Ethicon. A Kocher was used as an open instrument comparison. Flexiforce A401 thin-film force sensors were used to measure applied forces. Data were collected and calibrated using an Arduino Uno microcontroller board with Arduino and MATLAB software. Single-handed, complete closure of each device's ratcheting mechanism was performed 3 times. The maximum required input force in Newtons was recorded and averaged. The average output force was measured with a bare sensor and the same sensor between 2 different thicknesses of LifeLike BioTissue.RESULTS:The most ergonomic ratcheting grasper for a small-handed surgeon was identified by the output ratio: the highest output force relative to the required surgeon input (the most force for the least amount of effort). The Kocher required an average input force of 33.66 N, with its highest output ratio of 3.46 (112 N output). The Covidien Endo Grasp was the most ergonomic, with an output ratio of 0.96 on the bare force sensor (31.4 N output). The Snowden-Pencer Wavy grasper was the least ergonomic, with an output ratio of 0.06 when applied to the bare force sensor (5.9 N output). All graspers except for the Endo Grasp had improving output ratios as tissue thickness and subsequent grasper contact area increased. Input force above that provided by the ratcheting mechanisms did not increase output force in a clinically relevant amount for any of the instruments evaluated.CONCLUSION:Laparoscopic graspers vary widely in their ability to provide reliable tissue force without requiring excessive input by the surgeon, and a point of diminishing returns often exists with increased surgeon input over designed ratcheting mechanisms. Output force and output ratio are potential quantitative measures of the efficiency of laparoscopic instruments. Providing users with this type of data could assist in optimizing instrument ergonomics.

The shedding of pathogens by infected humans enables the use of sewage monitoring to conduct wastewater-based epidemiology (WBE). Although most WBE studies use data from large sewage treatment plants, timely data from smaller catchments are needed for targeted public health action. Traditional sampling methods, like autosamplers or grab sampling, are not conducive to quick ad hoc deployments and high-resolution monitoring at these smaller scales. This study develops and validates a cheap and easily deployable passive sampler unit, made from readily available consumables, with relevance to the COVID-19 pandemic but with broader use for WBE. We provide the first evidence that passive samplers can be used to detect SARS-CoV-2 in wastewater from populations with low prevalence of active COVID-19 infections (0.034 to 0.34 per 10,000), demonstrating their ability for early detection of infections at three different scales (lot, suburb, and city). A side by side evaluation of passive samplers (n = 245) and traditionally collected wastewater samples (n = 183) verified that the passive samplers were sensitive at detecting SARS-CoV-2 in wastewater. On all 33 days where we directly compared traditional and passive sampling techniques, at least one passive sampler was positive when the average SARS-CoV-2 concentration in the wastewater equaled or exceeded the quantification limit of 1.8 gene copies per mL (n = 7). Moreover, on 13 occasions where wastewater SARS-CoV-2 concentrations were less than 1.8 gene copies per mL, one or more passive samplers were positive. Finally, there was a statistically significant (p < 0.001) positive relationship between the concentrations of SARS-CoV-2 in wastewater and the levels found on the passive samplers, indicating that with further evaluation, these devices could yield semi-quantitative results in the future. Passive samplers have the potential for wide use in WBE with attractive feasibility attributes of cost, ease of deployment at small-scale locations, and continuous sampling of the wastewater. Further research will focus on the optimization of laboratory methods including elution and extraction and continued parallel deployment and evaluations in a variety of settings to inform optimal use in wastewater surveillance.

Water quality monitoring is an important part of water management and there are many examples of technical challenges throughout the water cycle from catchment to tap. The application of online monitoring and associated sensors will contribute to several key areas of the water business. Changing environmental conditions mean that the quality of source waters is showing increased variability, and early detection of changes in quality and impacts on the treatment process is vital..

In March, 2010, a 15-year-old girl presented to our accident and emergency department with altered mental status, nausea, and vomiting. During the previous evening she had been out with friends, and had consumed a white powdery substance together with alcohol. On the day of admission she had become increasingly unwell, with symptoms that could not be attributed to a hangover and presented to us in the afternoon. Upon arrival, our patient was somnolent with a Glasgow Coma Score of 11 she opened her eyes in response to speech, uttered inappropriate words, and localised to pain. Blood pressure was 108/58 mm Hg; pulse rate was 54 beats per min; respiratory rate was 15 breaths per min; and ear-temperature was 36°C. Arterial blood gas analysis and 12-lead electrocardiogram were normal. There was no evidence of external injury, neck stiffness, or localising neurological signs. Her pupils were dilated but reactive to light; there was no papilloedema. The remainder of the physical examination was normal.

There is considerable interest in identifying carbon dioxide capture processes that can be incorporated within Integrated Gasification and Combined Cycle (IGCC) systems. In this paper, two novel adsorption based process configurations are proposed to operate in the temperature window (250-500 degrees C) suitable for an IGCC process after the water gas shift reactor. These process configurations are numerically simulated with an in-house simulator MINSA (Monash Integrated Numerical Simulator for Adsorption), and the simulation results indicate that good performance can be achieved with low operating cost. Carbon dioxide purity of greater than 95% and carbon dioxide recovery of greater than 90% can be obtained by both process options. (C) 2009 Elsevier Ltd. All rights reserved.

The potential benefits of precombustion carbon dioxide capture are well documented, and adsorption remains a promising separation process in this area. This paper details work to identify and assess the potential of high temperature adsorbents suitable for precombustion capture.The aim of this paper is to schematically identify adsorbents that are suitable for carbon capture in different temperature ranges. A critical aspect of this work is to assess the materials not only in terms of carbon dioxide isotherms and absolute loading, but to consider the wide range of other properties that are required to achieve an industrially feasible adsorbent - selectivity, cycling capacity, stability, kinetics, high pressure loading, fate of other components (including water, H2S, NH3, CO and N-2). It is only when all these requirements are sufficiently met, that an adsorbent can be consider worthy of industrial consideration. A range of analytic screening tests are described to enable a full characterisation of the merit of a specific adsorbent.The adsorbents investigated are zeolites (NaX, calcium chabazite), commercially available hydrotalcite, layered double hydroxides/oxides (LDH/Os), and magnesium double salts. Each operates in a different temperature range and offers potential for integration within an Integrated Gasification and Combined Cycle precombustion process train.Some of the promising and significant conclusions of this work are -Magnesium double salts present very favourable carbon dioxide isotherms and demonstrate significant carbon dioxide loading and the isotherms are suitable for PSA or TSA operation at high temperature.LDHs or their derivatives as layered double oxides can adsorb up to 1.5mol/kg CO2. Water does not affect CO2 sorption, and the material has good recyclability in TSA.The selectivity of hydrotalcite is well documented. However there is no reported literature on the adsorptive behaviour of these materials with respect to trace components - H2S and NH3. These results are reported.Calcium chabazite displays useful CO2 loading potential in a unique temperature range around 200 degrees C.NaX has the potential to replace Selexol at an operating temperate of 130 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.

There is considerable interest in identifying carbon dioxide capture processes that can be incorporated within Integrated Gasification and Combined Cycle (IGCC) systems. In this paper, we studied materials screening for adsorption at high temperatures and established that zeolite 13X can be used as an adsorbent in the temperature range of 30 to 250°C, and magnesium double salts from 350 to 400°C. Double salts [1] are very promising materials for adsorption technology at these high temperatures. They have relatively high CO2 adsorption loading at 350°C (1.2mol/kg) with a rapid reduction in capacity to 0.2mol/kg when the temperature is increased above 400°C. In accordance with these materials’ characteristics, a PVSA (vacuum pressure swing adsorption) cycle was designed for zeolite 13X and a TPSA (temperature-pressure swing adsorption) cycle was designed for the double salt. These process configurations are proposed to operate in the temperature window (250-500C) [2] suitable for an IGCC process downstream of the water gas shift reactor. These process configurations were numerically simulated with our in-house adsorption simulator MINSA (Monash Integrated Numerical Simulator for Adsorption) [3], and the simulation results indicate that good performance can be achieved. Carbon dioxide purity of greater than 95% and a carbon dioxide recovery of greater than 90% can be obtained. Analysis of Adsorbents Isotherms of H2O, CO2 and N2 on 13X 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 0 100 200 300 400 500 600 partial pressure (kPa) ad os pr tio n lo ad in g (m ol /k g) H2O at 200C

Diagnostic analysis of reverse osmosis membranes that were fed with Western treatment plant (WTP) recycled water was investigated by both thermodynamic calculations and laboratory experiments in order to predict the feasibility of RO desalting for WTP. The thermodynamic calculations suggested that RO recoveries of 80–85% were feasible with careful control of feed water pH and the use of chemical additives such as antiscalants and chelating agents, it also predicted the major minerals of concern to be silica, calcium fluoride, calcium carbonate, and calcium phosphate. Following the thermodynamic simulations, diagnostic laboratory experiments were undertaken. The experiments showed that the major contributor to scale formation was indeed calcium phosphate and possibly another calcium based compound, which was strongly suspected to be calcium carbonate. Based on previously published literature that indicated anti-scalants did not substantially decrease the scaling effect of calcium phosphate and laboratory tests that indicated controlling the pH to 6.4 in the feed water dramatically reduced scaling formation, it was suggested that the feed water could be controlled by pH adjustments only. Inter-stage pH correction was suggested as an optional technique to enhance the overall water recovery to above 95%.

Both pressure swing adsorption (PSA) and vacuum swing adsorption (VSA) processes are often characterized by the slow evolution of temperature profiles to cyclic steady state (CSS). Perhaps most profound is the severe axial temperature profile that characterizes oxygen VSA occurring at the interface between a prelayer and the main adsorbent layer. This temperature profile or "cold spot" has been of much interest to the gas industry and adsorption researchers. Previous work (Wilson, S. et al. Ind. Eng. Chem. Res. 2001, 40 (12), 2701) has developed qualitative explanations of these temperature profiles. This paper describes a detailed experimental investigation of the process parameters that affect the axial CSS temperature profile in oxygen VSA. These experimental results are compared with a numerical model of the process and a simple predictive model. A conclusion of this work is that numerical models can accurately capture the CSS temperature profiles and that the simple model can account for some, but not all, of the observed effects. A better understanding of thermal profiles is necessary for the development of new thermal optimization strategies in oxygen VSA.

In a previous study (Webley, P. A.; He, J. Fast solution-adaptive Finite Volume Method for PSA/VSA Cycle Simulation. 1. Single Step Simulation. Comput. Chem. Eng. 2000, 23, 170 1), a fast, solution-adaptive finite-volume technique for the simulation of a single adsorption step for a variety of boundary conditions was described. In this study, we apply this method to the simulation of nonisothermal PSA/VSA cycles of general complexity. Using successive substitution, stage-wise node refinement, and control algorithms, rapid cyclic steady state can be achieved even for problems with very long dynamics. We illustrate the advantages of node refinement as a useful tool for accelerating convergence to cyclic steady state. Simultaneous incorporation of control techniques into the successive substitution framework allows for rapid convergence of the PSA process to design specifications. We compare the results of our simulator to experimental data for a two-bed VSA process and find good agreement in pressures, flows, and temperatures.

This paper investigates the thermal profiles that arise in oxygen VSA, which is a prominent example of a PSA bulk gas separation process. Experimentally, it is demonstrated that the severe axial thermal profile or "cold spot" that frequently characterizes oxygen VSA can only arise if there are multilayered adsorption beds or if there are readily adsorbed trace components (such as water) that create a de facto multilayered bed. A qualitative explanation is offered to explain how this cold spot is formed. This paper also details a technique for predicting the penetration of a water-loaded zone into an oxygen VSA adsorption bed based on the method of characteristics. The results of this technique compare well with experimental and numerically simulated results. Finally, this paper demonstrates that a water-loaded zone and an inert zone of activated alumina result in very similar cyclic steady-state thermal profiles, even though the transient behaviors are markedly different.

Industrial scale multilayered oxygen vacuum swing adsorption units are characterised by a severe axial temperature profile (cold spot) that can have a deleterious effect on the overall performance of the technology. This industrial problem has been recognised for some time now, however remains poorly understood. This paper outlines an approach to better understand and predict the evolution of the cold spot using a technique based on a multiple time scale decomposition of the temperature into two components. The cyclic adsorption process is characterised by two time scales that both contribute to the axial temperature profile in the adsorption bed. The fast time scale temperature profile is caused by cyclic adsorption and desorption of nitrogen with associated heating and cooling of the molecular sieve. The combined period for the adsorption and desorption steps is approximately one minute. The evolution of the slow time scale temperature profile is principally caused by the convection of gas through the bed and the convergence to cyclic steady state is approximately a thousand times slower than the fast time scale. These very different time scales result from the ratio of the thermal capacitance of the gas to the thermal capacitance of the solid. This enables the decoupling of the energy balance into two parts. The fast time scale component of the energy is simply the heat of adsorption/desorption. The fast time scale component can be solved independently of the slow time scale. This paper demonstrates that the benefits of this solution strategy are twofold. Firstly, the approach provides important physical insight into the nature of the evolution of the cyclic steady state temperature profile in the oxygen vacuum swing adsorption process. The results are shown to be consistent with experimental results and full numerical simulation. Secondly, through decoupling the components of the temperature profile significantly faster numerical solutions are possible.

This paper investigates the ability of a detailed numerical model of multiple-layer, non-isothermal, bulk gas pressure swing adsorption processes to match experimental data over a range of operating conditions. The experimental apparatus is a 2-bed, 8-step VSA process for air separation using multiple layers of alumina and CaX zeolite. Input parameters are determined independently of the VSA system and no parameters in the model are adjusted to improve the fit to experimental data. A limited range of system purities and pressure swings art examined to illustrate the ability of the numerical model to capture overall performance. In general good agreement is obtained between the model and the experimental data although accurate modelling requires careful attention to details that influence the thermal behaviour of the process. The numerical model can also represent the unusual temperature profiles characteristic of multiple-layered beds. Overall, while goad agreement can be obtained between model and experimentation, accurate design must still rely on experimental work. The model is, however, sufficiently accurate to permit approximate optimisation studies to be performed.

Control of pressure and vacuum swing adsorption systems is challenging due to the unsteady state nature of the processes and the high degree of system non-linearity. System purity. flow rates and pressure must be regulated to within small tolerances to ensure compliance with customer requirements. Traditionally, industry has applied multiple, individual PID controllers to pressure swing plants to provide the required control. However, control problems in the field have arisen due to the fact that the plants operate in a batch-like manner and are highly non-linear resulting in PID loop interaction and instability. This paper describes the experimental operation of the oxygen VSA process, with the PID scheme implemented on a pilot scale VSA plant and shows the open and closed-loop response of system purity, flow rate and process pressures to changes in external and internal disturbances. Limitations of the PID scheme are highlighted.

AbstractThe guiding agenda of international programs promoting intelligent manufacturing systems (IMS) has been the creation of advanced machines with artificial intelligence capable of coping with the complex and changing conditions that threaten to disrupt the increasingly “automatic” factory. This article argues that this needs to be broadened to incorporate the development of integrated sociotechnical production systems that effectively combine human and technical resources in creating “smart” systems capable of adapting technologies to firm specific conditions, utilizing data bases, customizing software rules and procedures, and ensuring the ongoing development of the sociotechnical system. This requires greater attention to the human resources and organizational requirements of interdisciplinary system design and implementation. In making this argument, the article draws upon recent Australian case study experiences in the implementation and customization of integrated CAD/CAM systems and European research into human‐centered CIM design.