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Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gynecologic and breast cancers share several risk factors. Breast cancer risk assessment tools can identify those at elevated risk and allow for enhanced breast surveillance and chemoprevention, however such tools are underutilized. We aim to evaluate the use of routine breast cancer risk assessment in a gynecologic oncology clinic. A patient-facing web-based tool was used to collect personal and family history and run four validated breast cancer risk assessment models (Tyrer-Cuzick (TC), Gail, BRCAPRO, and Claus) in a gynecologic oncology clinic. We evaluated completion of the tools and identification of patients at elevated risk for breast cancer using the four validated models. A total of 99 patients were included in this analysis. The BRCAPRO model had the highest completion rate (84.8%), followed by the TC model (74.7%), Gail model (74.7%), and the Claus model (52.1%). The TC model identified 21.6% of patients completing the model as having ≥20% lifetime risk of breast cancer, compared to 6.8% by the Gail model, and 0% for both the BRCAPRO and Claus models. The Gail model identified 52.5% of patients as having ≥1.67% 5-year risk of breast cancer. Among patients identified as high-risk for breast cancer and eligible for screening, 9/9 (100%) were referred to a high-risk breast clinic. Among patients that completed the TC breast cancer risk assessment in a gynecologic oncology clinic, approximately 1 in 5 were identified to be at significantly elevated lifetime risk for breast cancer. The gynecologic oncologist's office might offer a convenient and feasible setting to incorporate this risk assessment into routine patient care, as gynecologic oncologists often have long-term patient relationships and participate in survivorship care. • 21.6% of patients completing the Tyrer-Cuzick model had ≥20% lifetime risk of breast cancer. • The Tyrer-Cuzick model was more sensitive at identifying high-risk patients compared to Gail, Claus, and BRCAPRO models. • 52.5% of those who completed the Gail model had ≥1.67% 5-year risk of breast cancer, and thus eligible for chemoprophylaxis. [ABSTRACT FROM AUTHOR]

Abstract A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

Objective The aim is to reduce the pressure drop of the process gas system of the sulfur recovery unit and maintain the long-term operation of the unit. Methods Combined with the process characteristics and calibration conditions of the 100 kt/a sulfur recovery unit with Claus and tail gas purification process, the influencing factors of the system pressure drop of the process gas were found out through the research, calculation and data comparison of the typical equipment and pipeline pressure drop of the unit. Besides, according to the actual production, the influencing factors of the system pressure drop of the process gas were comprehensively analyzed, and the methods and measures to reduce the system pressure drop were proposed. Results The specific pressure drop values of the main equipment and pipeline of the unit were obtained by means of drawing and calculation: The pressure drop of the burner of the reaction furnace was 1.5 kPa. The pressure drop of each heat exchange equipment was about 1.0 kPa, and the total pressure drop of the heat exchange equipment of the process gas system was 6.0 kPa. The calculated pressure drop of the reactor bed was only 74 Pa, which had good low pressure drop performance. The pressure drop of the wet tower of the quench tower packing was 760 Pa, and the pressure drop of the absorption tower packing was 2.3 kPa. The pressure drop of a single wire mesh demister was 164 Pa, and the total pressure drop of the wire mesh demister in the system was 1.1 kPa. The system pressure drop of the process gas pipeline was 3.0 kPa, and the system pressure drop would increase by 15 Pa for each additional 1 m pipeline. The system pressure drop of the process gas was affected by the total flow of process gas, the burner of the reaction furnace, the heat exchange equipment, the reactor, the tower equipment, the wire mesh demister and the system pipeline. Conclusions By improving the raw material properties of the sulfur recovery unit, accurately controlling the air distribution of the sulfur furnace, protecting the catalyst performance of the reactor, and stabilizing the operating conditions of the towers, the system pressure drop of the process gas in the sulfur recovery unit can be maintained at a low level, which can create conditions for the long-term operation of the device. [ABSTRACT FROM AUTHOR]

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data. [ABSTRACT FROM AUTHOR]

Objective In order to study the catalyst mechanism of titanium dioxide sulfur recovery catalyst for Claus reaction process, the adsorption performance of the catalyst for hydrogen sulfide, sulfur dioxide and organic sulfur was studied. Methods Aiming at the adsorption and desorption of reactants and products involved in Claus chemical reaction on typical titanium dioxide catalyst, the adsorption properties of H2S and SO2 products under single and co-existing conditions and the adsorption properties of water vapor and sulfur dioxide products and the adsorption performance of water vapor and sulfur vapor products were studied by microreactor and mass spectrometry. Results Under the typical operating conditions of the 1st-order Claus reactor, both hydrogen sulfide and sulfur dioxide could be strongly adsorbed on the titanium dioxide catalyst, in which the adsorption of sulfur dioxide was stronger than that of hydrogen sulfide, and the saturated adsorption capacity of the former was 3. 3 times that of the latter. When the reactants and products both existed, the adsorption of the catalyst for hydrogen sulfide and sulfur dioxide would decrease, and the adsorption of sulfur vapor was stronger than that of water vapor. However, after deducting the adsorption amount produced by capillary condensation of sulfur vapor, the blocking effect of water vapor on Claus reaction was stronger than that of sulfur vapor. Conclusions The titanium dioxide catalyst developed based on the research results had been applied in three sets of sulfur recovery units. The results showed that the hydrolysis effect of organic sulfur was remarkable, and the hydrolysis rates of COS and CS2 were more than 90%. [ABSTRACT FROM AUTHOR]

Objective /\ good performance tail gas hydrogenation catalyst was developed to solve the problem of excessive SO, mass concentration in flue gas discharged from sulfur recovery unit. Methods The catalytic performance of active components of hydrogenation catalyst in tail gas treatment unit of natural gas purification plant for the main chemical reactions such as hydrogenation, hydrolysis and transformation was studied. The catalyst kinetics was studied by micro-reaction and dynamic characterization techniques to obtain the activation energy and reaction order of hydrogenation and hydrolysis reactions, so as to 1m prove the catalyst performance. Results Hydrogen adsorption on Co-Mo hydrogenation catalyst could inhibit the hydrogenation of SO,, and water adsorption on the catalyst could strongly inhibit and hinder the hydrolysis of COS. A hydrogenation catalyst was developed based on the research results of catalyst active components and kinetics. Conclusions Compared with Ni-W and Fe-Mo catalysts, the new developed catalyst has better SO, and sulfur hydrogenation performance, organic sulfur hydrolysis performance and CO conversion performance. It is suitable for the operating conditions of natural gas purification plant and refinery, and can achieve the goal of SO, mass concentration less than 400 mg/m" in the flue gas discharged from tail gas treatment unit. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

Freud’s research on sexuality was, without doubt, a paradigm shift in the temporary conception of childhood experiences in relation to adult life. From those first experiences arise mnemic material which retroactively constitute the place and function of the unconscious. The theory of a psychic temporality that governs mood process, among other things, brings into question the classic model of time in western societies. Freud’s relation to these issues is already observable in his first scientific work, where he faces issues related to the sexual differentiation and heterochrony of living beings. [ABSTRACT FROM AUTHOR]

The Claus process has been used for the conversion of H2S and SO2 to elemental sulfur. These two sulfur compounds need special attention because they are very poisonous with negative impact on both the environment and human health. Here, highly active Fe-Ni/TiO2 catalyst has been prepared and shaped by three different binders (bentonite, polyethylene glycol and carboxymethyl cellulose) into extrudes. Comparing the mechanical strength and surface area of prepared extrudes, the optimal shaped catalyst was selected with 20% of bentonite, 2% of PEG and 2% of CMC. The optimal catalyst was characterized by X-ray powder diffraction, temperature-programmed reduction, Brunauer-Emmett-Teller specific surface area, Barrett-Joyner-Halenda, scanning electron microscopy and energy-dispersive X-ray techniques and used for sulfur recovery process. The performance of this product for sulfur recovery via Claus process was excellent with the conversion of hydrogen sulfide of 76.77% and sulfur dioxide of 97.83%. The catalyst also provides high hydrolysis activity of CS2 (83.06%). Therefore, a highly active TiO2-supported shaped catalyst with 85.62% of conversion efficiency has been prepared successfully to convert the small amounts of H2S, SO2 and CS2 to elemental sulfur. [ABSTRACT FROM AUTHOR]

The Claus process consists of two basic stages: thermal and catalytic sections. In this study, modeling by a kinetic model and multi-objective optimization of the thermal section of Claus process were described. The industrial data of the South Pars Refinery in Asaluyeh, Iran was used to validate this model. In order to investigate the influences of the inlet flow rates of fuel and air, inlet stream temperature, furnace pressure and waste heat boiler (WHB) outlet temperature on the sulfur recovery efficiency, the steam production and the H 2 S/SO 2 ratio, a sensitivity analysis was done by simulator software. Three objects of the sulfur recovery efficiency, the steam production and the H 2 S/SO 2 ratio were optimized by using the software and a multi-optimization approach based on the response surface methodology. The results showed that the decrease of the sulfur recovery efficiency from 0.6129 to 0.6099 leads to the addition of 8.54 Kg mole/h to the medium pressure steam production capacity and more closeness of the H 2 S/SO 2 ratio to number 2 for better performance of the catalytic section. However, the 66% improvement in the H 2 S/SO 2 ratio leads to increase the conversion of H 2 S in the catalytic section, compensating the decrease of the sulfur recovery efficiency in the thermal section. Moreover, the total fuel consumption was reduced about 0.6843 kg mol/h. [ABSTRACT FROM AUTHOR]

According to the acid gas characteristics of low H2S volume fraction (41%-48%) in Yuanba Natural Gas Purification Plant, sulfur recovery unit adopts the conventional Claus un-conventional divided flow method to recover sulfur. The technology has the advantages of simple process, flexible operation and advanced automatic control. The sulfur recovery process has been applied on the sulfur recovery unit in Yuanba Natural Gas Purification Plant for one year. The results showed while H2S volume fraction in acid gas is 41%-48%, the Claus furnace temperature is above 1 050 ℃, the conversion rate of sulfur in furnace is 65%-68%, sulfur products reach the national high-class product quality index. The successful application of the technology in sulfur recovery unit of Yuanba Purification Plant will provide references for the similar equipment in natural gas purification plants. [ABSTRACT FROM AUTHOR]

Two solid sulfurizing agents used under different reaction temperatures were developed as ex-situ sulfurization catalysts of Claus tail gas hydrogenation. By studying the sulfurizing agents addition and the operating condition during the sulfurization process, it was determined that the sulfurization rate of the catalyst active components could reach the standard with the method of Energy Dispersive Spectrometer. The results of catalyst performance evaluation showed that catalyst could meet the performance requirement, which definited the feasibilities of sulfurization technology in Claus tail gas hydrogenation catalytic field. [ABSTRACT FROM AUTHOR]

The enrichment oxygen sulfur recovery technology is a series of Claus processes in which air is replaced by pure oxygen or oxygen-enriched air to increase the treatment capacity of unit. It has been 30 years since COPE technology first put into production in 1985. According to the oxygen concentration in enrichment oxygen air, the enrichment oxygen technology could be divided into three types, namely low-level (the oxygen molar fraction is no more than 28%), medium-level (the oxygen molar fraction is no more than 50%) and high-level (the oxygen molar fraction is from 50% to about 100%). The suitable technology should be selected based on the concentration of H2S and impurity need to be decomposed in acid gas when designing. As the temperature of combustion furnace can easily reach over 1 400 C through burning in enrichment oxygen, the main design points are the selection of burner, refractory, the determination of oxygen concentration in air, as well as the temperature control system of furnace. Now huge amount of sulfur containing crude oil are refined and coal chemical industry is booming in China. Along with the issuing and putting into effect of GB 31570 - 2015 Emission Standard of Pollutants for Petroleum Refining Industry, the oxygen enrichment technology will be developed with a good prospect and should be paid full attention on. [ABSTRACT FROM AUTHOR]

The most common result of BRCA1/2 mutation testing when performed in a family without a previously identified mutation is an uninformative negative test result. Women in these families may have an increased risk for breast cancer because of mutations in non-BRCA breast cancer predisposition genes, including moderate- or low-risk genes, or shared environmental factors. Genetic counselors often encourage counselees to share information with family members, however it is unclear how much information counselees share and the impact that shared information may have on accuracy of risk perception in family members. We evaluated 85 sisters and daughters of women who received uninformative negative BRCA1/2 results. We measured accuracy of risk perception using a latent variable model where accuracy was represented as the correlation between perceived risk (indicators = verbal and quantitative measures) and calculated risk (indicators = Claus and BRCAPRO). Participants who reported more information was shared with them by their sister or mother about her genetic counseling session had greater accuracy of risk perception (0.707, p = 0.000) than those who reported little information was shared (0.326, p = 0.003). However, counselees shared very little information; nearly 20 % of family members reported their sister or mother shared nothing with them about her genetic counseling. Family members were generally not aware of the existence of a genetic counseling summary letter. Our findings underscore the need for effective strategies that facilitate counselees to share information about their genetic counseling sessions. Such communication may help their relatives better understand their cancer risks and enhance risk appropriate cancer prevention. [ABSTRACT FROM AUTHOR]

Sulfur recovery is an important industrial process for fossil fuel clean consumption, in which HS is firstly separated from the gas stream from the hydrodesulfurization process or gasified gas of coal or biomass. Meanwhile, almost equivalent half amount of SO is produced from the boiler on-site due to the power and steam generation or the fluid catalytic cracking process in a refinery. Currently, HS is converted into elemental sulfur using Claus process, which is being used worldwide, and SO is removed from the flue gas using lime or lime water. The two sulfur removal technologies require lots of capital investment and operating cost. Here, we have developed a novel process for SO in flue gas to react with HS from the gasified gas stream, to convert them elemental sulfur by washing the flue gas and HS with liquid catalyst containing water stream, the sulfur in SO and HS is converted into elemental sulfur and floated in the washed solution pool, which can be filtered out. Here, the pilot test results of the aqueous phase ambient temperature sulfur recovery process has been described and analyzed. The system converted more than 1000 ppm of HS and 500-600 ppm of SO in the flue gas into elemental sulfur in aqueous phase at temperature below 100 °C. The flue gas was washed with our acid aqueous media, and the sulfur is formed in the aqueous acid catalyst solution and was filtered out. The sulfur powder has the same laser Raman spectra with the Claus process, with the main structure as S with high purity. [ABSTRACT FROM AUTHOR]

By self-defining the chemical reaction of the sulfur recovery process in the HYSYS software, taking different characteristics of the equipments into account, the simulation model of the sulfur recovery unit was established. The calculation results of the simulation model have a certain accuracy to be used as a reference for the engineering application. [ABSTRACT FROM AUTHOR]

Accurate individualized breast cancer risk assessment is essential to provide risk-benefit analysis prior to initiating interventions designed to lower breast cancer risk and start surveillance. We have previously shown that a manual adaptation of Claus tables was as accurate as the Tyrer-Cuzick model and more accurate at predicting breast cancer than the Gail, Claus model and Ford models. Here we reassess the manual model with longer follow up and higher numbers of cancers. Calibration of the manual model was assessed using data from 8,824 women attending the family history evaluation and screening programme in Manchester UK, with a mean follow up of 9.71 years. After exclusion of 40 prevalent cancers, 406 incident breast cancers occurred, and 385.1 were predicted (O/E = 1.05, 95 % CI 0.95-1.16) using the manual model. Predictions were close to that of observed cancers in all risk categories and in all age groups, including women in their forties (O/E = 0.99, 95 % CI 0.83-1.16). Manual risk prediction with use of adjusted Claus tables and curves with modest adjustment for hormonal and reproductive factors was a well-calibrated approach to breast cancer risk estimation in a UK family history clinic. [ABSTRACT FROM AUTHOR]

To mitigate concrete sulfur storage pits deterioration, it is important to understand the mechanisms leading to concrete deterioration. The Claus chemical process is the industry standard for obtaining sulfur from hydrogen sulphide gas (derived from natural gas). The deterioration of concrete pits can be from both environmental factors and chemical effects of the Claus process. This may take the form of corrosion, sulfation, acidic attack, thermal expansion, or polymerization. Corrosion occurs as a result of sulfuric acid formation. Reactions occur because of Claus products presence, ingress of water through the concrete matrix or from leaks in steam coils. Sulfation occurs mainly from catalyzing some of Claus products by concrete or its admixtures. An acid environment lowers the pH value of the concrete and leads to impacting the passive film protecting the reinforcing rebars. Effects of thermal expansion and polymerization are also discussed in this paper. Selection of the proper materials is crucial in the construction of a durable sulfur pit. Low porosity concrete prevents ingress of gas/liquid species inside the concrete and hence mitigates destructive chemical reactions inside the structure. Cementious materials that will lower the diffusion of gas and liquid such as silica will improve the durability of the sulfur pits. In addition, because of the pozzolanic reaction associated with the use of silica fume the Ca(OH) content will be reduced. Concrete with mineral additives such as silica fume will result in higher compressive strength, lesser permeability and higher corrosion and sulfate resistance. To assure the structure durability, designers need to understand and envision the operational conditions of sulfur pits. Utilization of wrong materials and construction practices can significantly shorten the expected service life of sulfur pits. Finally, repair of deteriorated sulfur pits needs also to be evaluated and conducted by specialized personnel. This repair can take many forms and scenarios including crack repair, structural members repair, durability liner, and structural liner. A proper strategized and engineered repair should be implemented to ensure the repair's effectiveness and durability. [ABSTRACT FROM AUTHOR]

The temperature steep rising of Claus reactor in shutdown process is likely to lead the sulfur recovery catalysts inactivation, or even bring an accident. Therefore, to prevent the temperature steeply rising in time is a very important way to protect the catalyst, reduce the accidents and economic loss. Aiming at the temperature steep rising accident in shutdown process in Sulfur Recovery Unit of YPC in 2012, this paper analyzed the reasons. According to the type of oxygen-enriched burners that had been used, methods such as reducing the oxygen ratio of acid gas combustion furnace, flowing nitrogen into the reactor, lowering the furnace temperature and inactivating the catalysts were used. The CT6-4B sulfur recovery catalysts in the reactor were protected efficaciously. Now the system is running well. [ABSTRACT FROM AUTHOR]

Subjugated to the linguistic and literary norms of the Netherlands and, at the same time, confined to the borders of the multilingual state of Belgium, Flemish authors have always had to struggle hard to legitimize their cultural identity. After the Second World War, however, Flemish literature suffered from an existential crisis due to the fact that a small but prominent part of the Flemish Movement had collaborated with the German occupiers. Publishers therefore had to explore new ways in which to turn Flemish literature into a commercially and artistically successful commodity in Flanders and the Netherlands. Introducing a theoretical framework that was conceived of by Pierre Bourdieu and further elaborated on by Pascale Casanova in The World Republic of Letters, this article will discuss and interpret the ways in which Flemish publishers have edited, designed, and marketed literary texts, and explore the positive and negative effects which strategies of assimilation and differentiation have had on the reception of those texts. The reading practices engaged in by literary gatekeepers, both in Belgium and in the Netherlands, are shown to have been a profoundly influential force in the history of Flemish literature. [ABSTRACT FROM AUTHOR]

Abstract: The need for fundamental data describing the dissolution of hydrogen sulfide, H2S, in Claus recovered liquid sulfur prompted an examination of equilibrium H2S solubility at typical industrial condensation temperatures and partial pressures. An FT/IR absorption technique has been described and new H2S solubility measurements have been reported for partial H2S pressures from 0.4 to 56kPa and temperatures from 120 to 155°C. The measurements were combined with previously reported values for atmospheric pressures of H2S and used to calibrate a semi-empirical equation for the Henry''s law solubility in liquid sulfur as a function of temperature. Estimations were compared to Claus plant field data and appear to underestimate the H2S solubility for the first and second catalyst condenser stages. This underestimation was attributed to rapid condensation resulting in super-saturation of the recovered sulfur liquid, or an inaccurate measurement of the condensation temperatures. [Copyright &y& Elsevier]

Effects of CO2 impurity in the range of 0–50 mol% in acid gas feed to a Claus once through process have been studied for air and pure oxygen combustion media. The process comprising a reaction furnace, three sulfur condensers and two converters is simulated. A computer program is developed. Results showed the effects on adiabatic flame temperature, heat recovery, sulfur recovery and equipment sizes using air and pure oxygen in combustion. Correlations were obtained for these effects. Adiabatic flame temperature could exceed the maximum allowable limit in furnace design when mol% CO2 is lower than 44% pure oxygen is used. In this case, SURE double combustion technique can be applied. Net heat recovery increases by about 3%, whereas overall sulfur recovery is practically not changed. Sx and COS in tail gas exceed ambient air allowable limit whereas CS2 is within the allowable limits, so further tail gas treatment is necessary. An increase in equipment size in the range of CO2 studied reaches up to 34% when air is used in combustion, whereas it reaches up to 98% when oxygen is used. By replacing air with oxygen for a specified CO2 concentration, a decrease up to 65% in equipment size is predicted. [ABSTRACT FROM AUTHOR]

A new modification is developed on conventional Claus process to increase the overall sulfur recovery as well as to decrease the costs. The modification combines both oxygen enrichment and recycling. The process is simulated and studied for various N2/O2 ratios with and without using SURE double combustion technique. The predictions show that using pure oxygen in combustion, condensing water vapor in a condenser following the first sulfur condenser and recycling the effluent gas to combine it with fresh acid gas feed leads to large savings in the production cost and to a clean environment. However, it leads to a high adiabatic flame temperature which exceeds the maximum allowable temperature of the furnace material of construction as well as its refractory. To avoid these effects, it is necessary to use SURE double combustion technique. The oxygen flow rate to the first combustion stage should not exceed 78% O2. [Copyright &y& Elsevier]

A mechanism for the conversion of H2S and SO2 over alumina is proposed in which surface thiosulfate is formed and reacts with SO2 and H2S via a series of oxy-anions to form sulfur and H2O. In addition to thiosulfate being a key species of the catalytic cycle, it is proposed that sulfate is also formed as part of the catalytic cycle but that its surface concentration is limited to some steady-state concentration by virtue of its reduction by H2S. The initial formation of thiosulfate and sulfate on alumina probably occurs by two mechanisms. One pathway involves interaction of either H2S or SO2 with oxide sites on the alumina surface. Such oxide sites have been suggested by Sohlberg et al. to arise as a consequence of the interaction of vacant sites in the defect spinel structure of alumina with H2O [J. Phys. Chem. 100 (1996) 7550]. The other pathway, the first step of which has been referred to numerous times in the literature, likely involves the adsorption of SO2 at Lewis acid–base sites, and reaction with H2S to form sulfur oxy-anions and eventually, sulfur and water. [Copyright &y& Elsevier]

Chemoprevention and prophylactic surgery are effective interventions for lowering breast cancer incidence. However, these approaches are associated with risks of their own. Accurate individualized breast cancer risk assessment is an essential component of the risk/benefit analysis that must take place prior to implementing either of these strategies. Several mathematical models for estimating individual breast cancer risk have been proposed over the last decade. The Gail model is the most generally applicable model; however, it neglects family history information in second-degree relatives, treats pre- and postmenopausal breast cancer the same, and ignores personal histories of lobular neoplasia. The Claus model is a better family history model, but it does not assign any special relevance to histories of bilateral breast cancer or ovarian cancer, and neglects all of the nonfamily history information accounted for by the Gail model. BRCAPRO is a Bayesian family history model that calculates individual breast cancer probabilities based on the probability that a family carries a mutation in one of the BRCA genes. Though its treatment of family history information is more thorough than the other models, it neglects the nonfamily history risk factors accounted for by the Gail model and may not appreciate familial clustering unrelated to BRCA gene mutation. A thorough understanding of the principles of risk analysis and the available mathematical models is essential for anyone wishing to perform intervention counseling. This review describes the basic components of risk analysis, explains how the mathematical models work and compares the strengths and weaknesses of the various models. CancerGene is a software tool for running all of these models. It may be obtained without charge at http://www.swmed.edu/home_pages/cancergene. [ABSTRACT FROM AUTHOR]

In der vorliegenden Studie wird die Morphologie einer neuen Art der Gatrung Heterocypris Claus, 1892, beschrieben (loc. typ.: Kolumbien, Sabana de Bogotá, Bogotá, Parque "El Lago"). Die neue Art unterscheidet sich von anderen Arten der Gattung durch die Struktur des Schalen sowie der Furka.The present study gives a description of the morphological structure of a new species of the genus Heterocypris Claus, 1892 (loc. typ.: Colombia, Sabana de Bogotá, Bogotá, Parque "El Lago"), recognizable among the remaining species of the genus mainly by the particular structure of the valves and the furcas.El presente estudio da una descripción de la estructura morfológica de una nueva especie del género Heterocypris Claus, 1892 (loc. typ.: Colombia, Sabana de Bogotá, Bogotá, Parque "El Lago") , distinguible de sus congéneres principalmenre por la estructura particular de las valvas y de las furcas.