Severe Stratification Research Articles

Effects of Microribs on the Thermal Behavior of Transcritical n-Decane in Asymmetric Heated Rectangular Mini-Channels Under Near Critical Pressure

Microrib is a very promising heat transfer enhancement method for the design of scramjet regenerative cooling channels. In this paper, a three-dimensional numerical model has been built and validated to parametrically investigate the thermal behavior of transcritical n-Decane in mini cooling channels with microribs under near critical pressure. The results have shown that the height and pitch of microrib perform a nonmonotonic effect on the convective heat transfer coefficient of n-Decane inside the cooling channel and the optimal microrib parameters stay at low values due to dramatic changes of coolant thermophysical properties in the near critical region. Due to severe thermal stratification and near critical conditions, there will be a significant recirculation zone in vertical direction near microrib, and its interaction with the strong secondary flow in axial direction caused by limited channel width of mini-channel will largely enhance the local convective heat transfer and its downstream region. Besides, the dramatically changing thermophysical properties of n-Decane will lead to a locally remarkable heat transfer enhancement phenomenon similar to impingement cooling at the front edge of microribs.

Experimental investigations of the heat load effect on heat transfer of ground heat exchangers in a layered subsurface

To experimentally investigate the effect of heat loads on the thermal performance of vertical ground heat exchangers (GHEs) in a layered subsurface, a series of experiments were conducted using a testing box filled with sand and clay. Temperature distributions during the operation and recovery periods were different in the layered subsurface, where materials with high thermal diffusivities (e.g. sand) excel in both heat transfer and recovery. With more heat transferred from tubes, the sand and clay located close to the tubes showed drastic temperature variations along the length of tubes, especially around the interface between layers. The thermal interference could enhance the layered thermal distribution in the stratified underground, especially in materials with low thermal diffusivities. Moreover, if the applied power increased by four times, the proportion of the temperature difference between sand and clay to the sand temperature increased from 12.9% to 32.7%, which indicated a more severe thermal stratification. Therefore, it is recommended to consider the effect of ground stratification for multi-GHEs with considerable thermal injection and severe thermal interference, especially in materials with low thermal diffusivities.

Panel of serum protein biomarkers to grade the severity of traumatic brain injury.

The Glasgow Coma Scale (GCS), which classifies patients into mild, moderate or severe traumatic brain injury (TBI), is a system used to prioritize treatment and prognosticate the severity of head injury. In this study, sera of patients with various stages of TBI, as well as control subjects, were analyzed to screen for proteins that may be used to complement the GCS system. By subjecting pooled serum samples to iTRAQ analysis for quantitative comparison of protein abundance, and attesting their altered levels using ELISA, we have detected increased levels of serum amyloid A, C-reactive protein, leucine-rich alpha-2-glycoprotein, lipopolysaccharide-binding protein, fibronectin, vitronectin and alpha-1-antichymotrypsin in patients across all strata of TBI relative to the controls. However, kininogen was decreased only in moderate and severe TBI, whereas apolipoprotein E and zinc-alpha-2-glycoprotein were only increased in severe TBI. Hence, we propose a panel of serum biomarkers, which if analyzed within 24 h of the injury, can be used to diagnose patients with TBI into mild, moderate or severe stratification objectively, thus complementing the traditional GCS.

Subsurface low dissolved oxygen occurred at fresh- and saline-water intersection of the Pearl River estuary during the summer period

Estuarine oxygen depletion is one of the worldwide problems, which is caused by the freshwater-input-derived severe stratification and high nutrients loading. In this study we presented the horizontal and vertical distributions of dissolved oxygen (DO) in the Pearl River estuary, together with temperature, salinity, chlorophyll a concentration and heterotrophic bacteria abundance obtained from two cruises during the summer (wet) and winter (dry) periods of 2015. In surface water, the DO level in the summer period was lower and varied greater, as compared to the winter period. The DO remained unsaturated in the summer period if salinity is <12 and saturated if salinity is >12; while in the winter period it remained saturated throughout the estuary. In subsurface (>5m) water, the DO level varied from 0.71 to 6.65mgL−1 and from 6.58 to 8.20mgL−1 in the summer and winter periods, respectively. Particularly, we observed an area of ~1500km2 low DO zone in the subsurface water with a threshold of 4mgDOL−1 during this summer period, that located at the fresh- and saline-water intersection where is characterized with severe stratification and high heterotrophic bacteria abundance. In addition, our results indicate that spatial DO variability in surface water was contributed differently by biological and physio-chemical variables in the summer and winter periods, respectively.

On the possible role of thermal radiation in containment thermal–hydraulics experiments by the example of CFD analysis of TOSQAN T114 air–He test

One of the experiments of ERCOSAM–SAMARA (E–S) projects (TOSQAN T114) is examined from the viewpoint of the radiative heat transfer (RHT) contribution to the overall heat exchange. E–S projects and T114 test were focused on investigation of light gas stratification in severe accident containment atmosphere and stratification break-up after the activation of mitigation systems. The first from two phases of T114 test is considered during which helium is quasistatically injected into the upper part of the TOSQAN vessel having isothermal walls and initially filled by air. The developing free convection removes most of the heat acquired, but not all. Thus stable local deviations in calculated temperatures were obtained in simulations that were interpreted as the deficiencies of the physical heat-transfer model. The modeling of RHT was included in full CFD simulation that resulted in a better agreement in local temperatures. The results of comparative calculations performed without/with RHT modeling are described in the paper. The RHT model implemented in the used CFD code (ANSYS FLUENT) was tested on known analytical solutions. The RHT contribution in T114 test was also estimated analytically to demonstrate independently that it may be noticeable in this experiment. The same estimations may be valid for stagnant zones of severe accident containment. All that shows the need in further detailing of the role of RHT in gas-structure heat exchange: as for interpretation of some containment tests performed in pressure vessel as for containment modeling.

Paediatric procedural sedation using ketamine in a UK emergency department: a 7 year review of practice

BackgroundKetamine is growing in popularity for procedural sedation in the paediatric population, yet safety concerns remain. We performed a retrospective review of practice and outcomes of paediatric ketamine sedation using the World SIVA International Sedation Task Force reporting tool. MethodsA retrospective inspection of the dedicated emergency department electronic sedation database and subsequent note and sedation chart review was performed for all paediatric sedations throughout a 7 yr period from September 2006. All adverse events were stratified. ResultsDuring the study period, procedural sedation was provided for a total of 243 children, of whom 215 were sedated with ketamine, most commonly for wound management (n+131). The median patient age was 4 yr (14 months to 15 yr), and 63.7% were male. Of the total, 76.7% were discharged home either directly (n+101) or after brief observation (n+64). One patient required subsequent general anaesthesia after a failed sedation with paradoxical agitation. Of the total, 9.8% of patients had an adverse event, the most severe risk stratification being ‘minor risk’. All interventions were ‘minimal risk’. There were no ‘sentinel risk’ outcomes. ConclusionsThese data support the ongoing use of ketamine for paediatric procedural sedation in the emergency department by emergency physicians. Relatively high resource requirements mean that ensuring adequate numbers of procedures may prove challenging.

Malignant Otitis Externa: A Novel Stratification Protocol for Predicting Treatment Outcomes.

1) Stratify malignant otitis externa into severe and nonsevere disease categories. 2) Predict treatment courses and outcomes based on this stratification. Tertiary center. Retrospective review 2004 to 2014; 28 patients. Inclusion criteria are a diagnosis by senior authors, radiographic evidence of disease, admission for intravenous antibiotics/debridement, minimum 1 year of follow-up. Severe group stratification if two or more of the following: cranial nerve VII palsy, fungal positive culture, relapse, surgery performed, major radiographic findings. All other patients stratified to nonsevere group. Cure, alive/refractory disease, death by disease, death by other cause. Secondary measures are antibiotic duration and number of disease-related admissions. Forty-three percent (12 of 28) and 57% (16 of 28) of patients stratified into the severe and nonsevere groups. The severe group had significantly more adverse disease-specific outcomes than the nonsevere group (7 of 12 versus 0 of 16; p = 0.002). Disease-specific mortality was 42% and 0% in the severe and nonsevere groups, respectively. The severe group had longer antibiotic courses (12.8 versus 6.9 wk; p = 0.01) and more disease-related admissions/relapses (1.6 versus 1, p < 0.001). Only four of 12 severe group patients achieved cure. All but two nonsevere patients achieved cure, with those two dying of other causes. A subgroup of malignant otitis externa may exist that is not as susceptible to parenteral antibiotics and local debridement. A combination of clinical and radiographic findings may be useful for stratifying patients into severe/nonsevere categories. Patients with severe disease may be more likely to die of their disease and have worse treatment courses such that additional surgical intervention may be indicated.

“Stratifiability index” – A quantitative assessment of acid stratification in flooded lead acid batteries

A methodology is presented to quantify acid stratification in flooded lead acid batteries and compare different types of batteries regardless of their design features and size by means of the proposed “stratifiability index”. This index describes to what degree acid stratification develops in flooded lead acid batteries. Different test procedures are proposed which induce severe acid stratification within 48 h and lead to significantly different degrees of acid stratification. The test procedures are intended to assist in the development and selection of batteries which are less prone to develop severe acid stratification.

새만금 내부개발이 체류시간 및 수질변화에 미치는 영향

새만금호 내부개발에 따른 호 내측의 수리특성과 수질환경 영향을 분석하기 위해 EFDC 모형을 이용한 심층적인 수치모의가 수행되었다. 개발이 진행되면서 방수제 및 준설 영향으로 표·저층간의 흐름특성이 변화된다. 특히 관리수위 적용에 따른 제한적인 배수갑문 운영은 기존과 다르게 표·저층간 성층발달을 심화시켜 새만금호 내측의 수질환경을 악화시키는 주요 인자로 확인되었다. 무작위행보에 의한 입자추적방법을 이용한 내부 체류시간 분석을 통해 확인된 특성은 평수시와 홍수시 그 특성이 크게 다르지만, 만경호 북측구역은 일종의 사대로 변화되어 오염물질이 장기간 체류되면서 침적된 저니층의 용출로 인해 수질환경이 악화되는 주요 원인으로 작용할 것으로 추론되었다.

Digital cinema: an alternative model for post-apartheid cinematic production and consumption?

Patterns of cinematic production and consumption are often symptomatic of wider politico-economic and socio-cultural forces. This is the case in South Africa, where this site of cultural production, like the society as a whole, is marked by severe racial stratification and division. One finds, for example, that as a direct result of apartheid inequality, the majority of the population has been alienated from the mechanisms of cinematic production and consumption. This fragmentation remains one of the greatest challenges to the sustainability and racial transformation of the post-apartheid film industry. In this article I present a critical discussion on the rise of the low-budget, digital film in South Africa. With careful reference to prevailing politico-economic conditions and available state-support measures I analyse the potential of digital technology to revolutionise cinematic production and consumption practices. In analysis, it was found that while cinema has indeed become somewhat more accessible, the production, distribution and exhibition of motion pictures in South Africa remain monopolised, exclusive and inaccessible to the majority. Moreover, it is questionable whether the digitised consumption mechanisms in place penetrate a wide enough market to sustain the movement. Therefore, although this is indeed an exciting movement in the industry, it should not be viewed as an outright replacement of existing technology nor a means for independent filmmakers to make it alone. On the contrary, it is most likely to run parallel to existing entertainment mechanisms and state support will still be required to encourage diversity and encourage sustainability.

An improved virtual calibration of a supply air temperature sensor in rooftop air conditioning units

Accurate supply air temperature (SAT) measurements are vital for improving the energy management of packaged rooftop air-conditioning units (RTUs) through better sequencing control and real-time automated fault detection and diagnosis (FDD). However, the accuracy and reliability of single measured manufacturer-installed supply air temperature (MSAT) are greatly compromised in the heating mode due to severe temperature stratification and high thermal radiation. There exists unacceptable erratic measurement errors and the traditional calibration method can hardly overcome the defect. An easy-to-use and very cost-effective nontraditional calibration method was proposed previously to calibrate virtually an MSAT sensor in RTUs. In order to overcome the deficiencies of the virtual calibration (VCal) method in fault tolerance and fault diagnostics, experiments with wider combination and coverage are investigated in this study. It is found that an improved virtual calibration (IVCal) method can be obtained by correlating the offset errors with available system information (the outside air damper status[OADst]) and low-cost temperature measurements (the MSAT and outside air temperature [OAT]). Further experimental evaluations demonstrate that the IVCal method could predict the true value of SAT with greater accuracy (at a relative error of only ±1.4°F [0.8°C]) with excellent fault tolerance and significantly enhanced performance of a virtual supply airflow rate meter. Additionally, the IVCal method also inherits the good characteristics of the VCal method, such as its high cost-effectiveness, ease of use, and applicability to all RTUs with similar constructed gas furnaces.

Soil controls of phosphorus in runoff: Management barriers and opportunities

Kleinman, P. J. A., Sharpley, A. N., Budda, A. R., McDowell, R. W. and Allen, A. L. 2011. Soil controls of phosphorus in runoff: Management barriers and opportunities. Can. J. Soil Sci. 91: 329–338. The persistent problem of eutrophication, the biological enrichment of surface waters, has produced a vast literature on soil phosphorus (P) effects on runoff water quality. This paper considers the mechanisms controlling soil P transfers from agricultural soils to runoff waters, and the management of these transfers. Historical emphases on soil conservation and control of sediment delivery to surface waters have demonstrated that comprehensive strategies to mitigate sediment-bound P transfer can produce long-term water quality improvements at a watershed scale. Less responsive are dissolved P releases from soils that have historically received P applications in excess of crop requirements. While halting further P applications to such soils may prevent dissolved P losses from growing, the desorption of P from soils that is derived from historical inputs, termed here as “legacy P”, can persist for long periods of time. Articulating the role of legacy P in delaying the response of watersheds to remedial programs requires more work, delivering the difficult message that yesterday's sinks of P may be today's sources. Even legacy sources of P that occur in low concentration relative to agronomic requirement can support significant loads of P in runoff under the right hydrologic conditions. Strategies that take advantage of the capacity of soils to buffer dissolved P losses, such as periodic tillage to diminish severe vertical stratification of P in no-till soils, offer short-term solutions to mitigating P losses. In some cases, more aggressive strategies are required to mitigate both short-term and legacy P losses.

Predictive modeling in case-control single-nucleotide polymorphism studies in the presence of population stratification: a case study using Genetic Analysis Workshop 16 Problem 1 dataset

In this paper, we apply the gradient-boosting machine predictive model to the rheumatoid arthritis data for predicting the case-control status. QQ-plot suggests severe population stratification. In univariate genome-wide association studies, a correction factor for ethnicity confounding can be derived. Here we propose a novel strategy to deal with population stratification in the context of multivariate predictive modeling. We address the problem by clustering the subjects on the axes of genetic variations, and building a predictive model separately in each cluster. This allows us to control ethnicity without explicitly including it in the model, which could marginalize the genetic signal we are trying to discover. Clustering not only leads to more similar ethnicity groups but also, as our results show, increases the accuracy of our model when compared to the non-clustered approach. The highest accuracy is achieved with the model adjusted for population stratification, when the genetic axes of variation are included among the set of predictors, although this may be misleading given the confounding effects.

Amorphous sol–gel SiO 2 film for protection of Ti6Al4V alloy against high temperature oxidation

Amorphous SiO 2 thin films were deposited on Ti6Al4V alloy by sol–gel processing. Isothermal and cyclic oxidation tests of the coated and uncoated specimens were performed at 700 and 800 °C. The SiO 2 film exhibited beneficial effects on the oxidation resistance of the alloy. Titania scales formed on the uncoated specimens, and severe spallation and stratification of the scales were observed. The oxidation rates of the silica coated specimens were decreased significantly. The silica film shrunk to about a quarter in thickness, probably by mechanism of crystallization of silica and evaporation of the organic additments. The oxide scales formed on the coated specimens were multilayered. Beneath the silica film, formation of a thick rutile titania layer followed by a thin alumina layer occurred. Above the silica film, alumina plus minor titania layer formed. It is deduced therefore that the growth of the multilayered and mixed oxide scales was dominated by both outward diffusion of metal and inward diffusion of oxygen.

Response to Loss-of-Function Mutation in Tryptophan Hydroxylase-2 Identified in Unipolar Major Depression. Neuron 45, 11–16

Zhang and colleagues reported the G1463A variant (c.1322G>A) that predicted an amino acid substitution at a highly conserved position in tryptophan hydroxylase-2 (TPH2) (p.Arg441His). Functional analysis of 441His showed an ∼80% loss in serotonin production when expressed in PC12 cells. The authors' genetic data showed the presence of the 1463 A-allele in 9 of 87 elderly unipolar affective disorder (UP) patients (>60 years) and in 3 of 219 healthy control individuals. Based on these finding, we genotyped the G1463A variant in two large patient-control samples obtained in northern-Sweden and Belgium. The northern-Swedish sample was comprised of 135 UP patients (87 females, 48 males, mean age at inclusion was 56.6 years), 182 bipolar (BP) patients (96 females, 86 males, mean age at inclusion was 56.3 years), and 364 healthy age-, gender-, and ethnicity-matched control individuals. The Belgian sample consisted of 182 UP patients (121 females, 61 males, mean age at inclusion was 46.6 years), 182 BP patients (99 females, 83 males, mean age at inclusion was 45.3 years) and 364 healthy age-, gender-, and ethnicity-matched control individuals. Genotyping was performed by pyrosequencing on a PSQ™HS96 pyrosequencer (http://www.pyrosequencing.com/) with the use of 5′-bio-GTTTATTCTGCAGGGACTTTGC-3′ and 5′-CGAAGGTCCTGCACCACA-3′ as PCR primers and 5′-GAAGTATACTGAGAAGG-3′ as reverse sequencing primer. We did not observe the A-allele in any of the patients nor in the control individuals. To confirm the validity of our pyrosequencing assay, we subsequently sequenced genomic DNA of all patients and control individuals by using PCR-based direct sequencing with primers 5′-AGCCTTTGACCCAAAGACAA-3′ (forward) and 5′-AGATCATGCTGGCAACAACA-3′ (reverse). Sequence trace files were analyzed for the occurrence of the G1463A variant with novoSNP (Weckx et al., 2005Weckx S. Del-Favero J. Rademakers R. Claes L. Cruts M. De Jonghe P. Van Broeckhoven C. De Rijk P. Genome Res. 2005; 15: 436-442Crossref PubMed Scopus (201) Google Scholar) and visual inspection. The sequencing data confirmed the absence of the 1463A-allele in all subjects. This unexpected absence of the TPH2 1463A-allele in 681 patients with affective disorders and 728 control individuals from two independent patient-control cohorts obtained from northern-Sweden and Belgium raises doubts about the true nature of this polymorphism. Even if the A-allele was rare in our Caucasian populations, it would have a frequency of <1/2818 chromosomes, or <0.035%. This contradicts the high prevalence of this polymorphism in 15/662 chromosomes (2.3%) in Caucasians reported by Zhang et al., 2005Zhang X. Gainetdinov R.R. Beaulieu J.-M. Sotnikova T.D. Burch L.H. Williams R.B. Schwartz D.A. Krishnan K.R.R. Caron M.G. Neuron. 2005; 45: 11-16Abstract Full Text Full Text PDF PubMed Scopus (359) Google Scholar. Because the authors selected older patients (>60 years) for their study, we cannot exclude that the A-allele is enriched due to an associated protective survival effect. However, because the frequency of affective disorders is very similar worldwide and no studies have reported increased survival due to reduced serotonin levels, this assumption is unlikely to explain their genetic data. Furthermore, 7 of the 9 depressed patients with the 1463A-allele failed to respond to SSRI treatment, while 2 patients required high concentration. Therefore, it seems more plausible that the observed high frequency of the 1463A-allele reported by Zhang et al., 2005Zhang X. Gainetdinov R.R. Beaulieu J.-M. Sotnikova T.D. Burch L.H. Williams R.B. Schwartz D.A. Krishnan K.R.R. Caron M.G. Neuron. 2005; 45: 11-16Abstract Full Text Full Text PDF PubMed Scopus (359) Google Scholar is the result of severe patient population stratification based on age of inclusion and/or SSRI treatment failure. Anyway, even with the strong functional data of which we do not doubt the quality, the report of a functional relevant genetic THP2 polymorphism associated with affective disorders is at this stage uncertain and needs to be replicated independently. Even more, recent guidelines for genetic association studies in complex diseases are firm when it comes to sample sizes and replication, even for functionally relevant variants in important candidate genes, and therefore warrant genotyping the G1463A variant in large patient-control populations (Smyth et al., 2005Smyth D.J. Howson J.M.M. Lowe C.E. Walker N.M. Lam A.C. Nutland S. Hutchings J. Tuomilehto-Wolf E. Tuomilehto J. Guja C. et al.Nat. Genet. 2005; 37: 110-111Crossref PubMed Scopus (55) Google Scholar, Qu et al., 2005Qu H. Bharaj B. Liu X.-Q. Curtis J.A. Newhook L.A. Paterson A.D. Hudson T.J. Nat. Genet. 2005; 37: 111-112Crossref PubMed Scopus (6) Google Scholar).

Persistent Holocene Outflow from the Black Sea to the Eastern Mediterranean Contradicts Noah's Flood Hypothesis

Controversy surrounds reconnection of the Black Sea and Mediterranean during Holocene sea-level rise. This reconnection and its causes have implications for European and Middle Eastern archaeology, paleoclimate, and marine sedimentation; e.g., genesis of organic-rich muds (sapropels). Bill Ryan, Walter Pitman, and co-workers propose reconnection via a catastrophic flood of Mediterranean water into the Black Sea at ca. 7.5 ka, with speculation that this was the historical basis for the biblical story of Noah's Flood. In contrast, this paper suggests a more complex and progressive reconnection over the past 12 k.y. Today, the Black Sea exports considerably more brackish water than the saline inflow it receives from the Mediterranean. There is a stratified, two-layer flow that has a strong effect on aquatic life and seabed sediments. The Sea Gateway (narrow straits of Dardanelles and Bosphorus, and deep intervening Marmara Sea) provides a set of natural flow valves (and sediment traps) that in principle should contain a record of the reconnection. Using ~7500 line-km of seismic profiles, 65 soft-sediment cores, and 43 radiocarbon dates, we recognize a 10-11 k.y. history of low surface- water salinities in the Marmara Sea and northern Aegean Sea. The low-density surface layer promoted uninterrupted water-column stratification and depleted oxygen concentrations at depth and is attributed to persistent Black Sea outflow across the Bosphorus Strait. Seismic data reveal a climbing delta on the middle shelf south of the Bosphorus exit, active only from ca. 10 to 9 ka based on radiocarbon dating of its distal prodelta. The strength of the early outflow is confirmed by the progradation of this delta, and contemporaneous severe water-column stratification leading to deposition of sapropels in basinal areas. Ryan and Pitman's argument for a catastrophic Black Sea flood hinges on the rapid first appearance of euryhaline (Mediterranean) mollusks on Black Sea shelves at ca. 7.5 ka. In our view, this colonization was not a consequence of catastrophic flooding but rather the outcome of a slow establishment of two-way flow in the Bosphorus and a time lag during which the fresher waters of the deep Black Sea were replaced by more saline inflow, eventually allowing marine organisms to colonize the Black Sea shelves.

Mixing and dispersion of particle ropes in lean phase pneumatic conveying

The objective of this study was to investigate mixing mechanisms in lean phase pneumatic conveying, with the emphasis on techniques for dispersing the severe particle stratification caused by flow through a 90° elbow. This type of stratification is referred to as a particle rope. The paper describes a combined numerical and experimental study of the rope dispersion characteristics of various mixing devices that were installed immediately downstream of the elbow. The laboratory experiments were conducted in a 0.154 m I.D. vertical test section. Local particle velocities and concentrations were measured using a reflective type fiber optic probe. The numerical simulations were carried out using the CFX-4.2 code developed by AEA Technology. The effect of secondary velocities on rope dispersion was investigated by using a flow straightener installed after the elbow. The results show that the rope dispersion rate in both the axial and radial directions was significantly reduced in the absence of secondary velocities. The types of flow mixers investigated included nozzles, air jet injection, and swirl vanes. Although all mixing techniques were able to disperse the particle rope within nine pipe diameters from the bend exit plane, nozzles with beta ratios of 0.5 and 0.67 and air jet injection from the inner wall caused the most rapid rope dispersion. However, the nozzles cause excessive pressure drop and the air jet injection technique increases the flow rate of conveying fluid carried by the pipe.

Density Relaxation of Liquid–Vapor Critical Fluids in Earth's Gravity

Experimental results of the density relaxation of a liquid–vapor critical fluid in Earth's gravity over a temperature regime of severe density stratification are presented. A 10-mm-diameter × 1-mm-thick disk-shaped sample of SF6 was placed in a Twyman–Green phase shifting interferometer with a phase uncertainty of 1/65 of a wavelength over 60 h. Relaxations to equilibrium stratification were observed for a temperature range from 1.0 to 29.6 mK above Tc, where Tc is the critical temperature. The interferometry provided a density distribution history over the full extent of the sample cell. Two types of initial density states were established before stepping to the final temperature (density) states for relaxation: (1) the two-phase state at Tc−50 mK and (2) the equilibrium state at Tc+100 mK. Upper and lower portions of the cell relaxed differently for these two initial states. For the Tc+100 mK initial state, relaxation to T<Tc+3 mK showed an early density overshoot followed by an additional long-time relaxation not seen in the other relaxation sequences. Otherwise, relaxations were faster and increasingly nondiffusive (without a unique exponential description) as the final state became closer to the critical temperature.

An Investigation of Thermal Stress Ranges Under Stratification Loadings

This paper deals with a unique and severe stratification phenomena in the pressurizer surge line piping system. The methodology used in the calculation of total stress state includes pressure stresses from internal pressure, global thermal stresses from the constraining of the system by supports, local thermal stresses from hot/cold stratified condition, and transient thermal stresses in the pipe and at structural discontinuities. Special discussion on the interpolation to obtain moment loadings from one state of thermal condition to the next with nonlinear gapped support system is presented. Finally, the thermal cycling associated with operating transients in the surge line system is also addressed.

In-Situ Leaching of South Texas Uranium Ores: Part 3-Post-Leach Assessment of Recovery and Sweep Efficiency

Summary This paper reports results of a post-leach study following nearly 3 years' uranium in-situ leaching in a south Texas ore body. Wells drilled in strategic locations were logged [including delayed fission neutron (DFN) and gamma ray logs] and cored and the recovered core chemically analyzed. Overall uranium recovery for the total 11.9-m [39-ft] ore zone was about 70%, estimated from core and log data. Although ammonia analyses gave evidence of some leachate contact at some time over the whole interval, uranium recovery was not uniform over the total 11.9 m [39 ft]. The upper half of the ore zone appears to have been leached exhaustively, showing not only complete uranium depletion but zero reducing capacity. In the lower half of the interval, however, there was evidence of severe reservoir stratification. There were two narrow, visually oxidized bands from which uranium had been leached. These were interposed between three zones containing strong uranium shows, which had been totally or partially bypassed by the leaching fluid. Lithological cross sections suggested that, in the bypassed zones, a higher degree of sand compaction or the presence of clayballs or clay streaks caused lower permeability, thereby presence of clayballs or clay streaks caused lower permeability, thereby severely limiting the accessibility of the uranium mineral to the injected fluids. Introduction In the past few years in-situ leaching has become an important alternative to open-pit and shaft-mining recovery of uranium. In-situ leaching has a high potential for recovering reserves not presently minable by conventional techniques and with minimal disturbance of the surface environment. Water requirements are much less than in a conventional mine, and undesirable tailings ponds are not needed. Many leaching studies have been reported for south Texas, including case histories of field operations and commercial-size projects. Great interest in this technology is indicated by the more than 12 pilot and commercial in-situ projects in operation in south Texas in 1981. Reservoir engineering aspects of in-situ uranium leaching are similar in some respects to oilfield waterflooding operations. Factors affecting in-situ leaching performance include areal sweep efficiency, vertical stratification, and permeability/porosity variations. Unlike waterflooding, however, leachate/ore contact is fundamentally the most important aspect of in-situ uranium leaching and in many instances the most difficult to achieve. Since most uranium exists in a chemically reduced form, contact between uranium mineral and fluid-containing oxidant is required to form a soluble product. Most leachate/ore contacting problems result from reservoir stratification, specifically where there are adjacent channels of widely varying permeabilities. When uranium occurs in the lower-permeability layers, contact with leachate is sometimes difficult or impossible. The contacting problems encountered with in-situ leaching contrast with uranium ore processing mills, where a high surface area is exposed by mechanical means. Very little documentation is available for post-leach analyses of in-situ uranium leaching projects, partly because of the large expenditure of time and money necessary to complete a post-leach study and the many technical problems associated with such a project. An important problem associated with any post-leach analysis is obtaining a "control" sample before the injection of leachate. A representative control sample is particularly difficult to obtain if horizontal correlation is not good -- particularly difficult to obtain if horizontal correlation is not good -- i.e., if the formation is laterally heterogeneous in mineralogy or permeability, or if there is cross bedding (non-horizontal layering). The permeability, or if there is cross bedding (non-horizontal layering). The later validity of the post-leach analysis will depend largely on how much preleach information was obtained, and how accurately the data describe the preleach information was obtained, and how accurately the data describe the formation. This is especially dependent on the type of logs available and the number and location of the determinations. The uranium ore body in which the present coring was performed lies in the Oligocene-Miocene Catahoula formation of south Texas. These deposits are commonly found in ancient fluvial sediments along the flanks of major fluvial channel-fill and occasional crevasse-splay facies. They frequently show the characteristic C-shape roll-type geometry, with mineralization at the interface of oxidized sediments and reduced pyritic sands. JPT p. 1018