bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy and tolerance of GELOXD/P‐GEMOXD in newly diagnosed nasal‐type extranodal NK/T‐cell lymphoma: A multicenter retrospective study
Authors: Li Ji‐Wei , Li Ya‐Jun , Zhong Mei‐Zuo , Liu Xian‐Ling , Li Jin , Li Kun‐Lun , Liu Xi‐Yu , Zhou Fang , OuYang Zhou , Sun Zhong‐Yi , Huang Li‐Jun , He Jun‐Qiao , Zhou Hui , Yi Ping‐Yong
Published: November 2017

Objectives

Nasal‐type extranodal natural killer NK/T‐cell lymphoma (ENKTCL) is a distinct type of non‐Hodgkin lymphoma with poor prognosis. This research aimed to evaluate the efficacy and safety of the GELOXD or P‐GEMOXD regimens in patients with ENKTCL.

Methods

Newly diagnosed ENKTCL patients treated with either the GELOXD or the P‐GEMOXD regimen were identified from three cancer centers between January 2010 and December 2016. Kaplan‐Meier and Cox regression analyses were used to calculate overall survival (OS) and progression‐free survival (PFS) and to investigate prognostic factors.

Results

One hundred and eighty‐four cases were identified from three cancer centers. After 1‐5 treatment cycles of GELOXD or P‐GEMOXD chemotherapy, 155 (84%) patients showed a complete response (CR). The 3‐year OS (73.0% vs 38.2%, P = .001) and PFS (72.8% vs 32.4%, P = .000) rates were significantly higher in early‐stage patients compared with advanced‐stage patients. A multivariate analysis revealed that patient CR status was a significant independent factor in disease prognosis. Grade 3/4 leukopenia occurred in 43 (23.4%) patients. Major non‐hematological toxicities included nausea (n = 117, 63.6%) and vomiting (n = 66, 35.9%).

Conclusions

The GELOXD and P‐GEMOXD chemotherapy regimens are well tolerated and provide favorable survival outcomes in patients with ENKTCL.
Prediction of Groundwater Level in Ardebil Plain Using Support Vector Regression and M5 Tree Model
Authors: Sattari Mohammad Taghi , Mirabbasi Rasoul , Sushab Reza Shamsi , Abraham John
Published: November 2017

The Ardebil plain, which is located in northwest Iran, has been faced with a recent and severe decline in groundwater level caused by a decrease of precipitation, successive long‐term droughts, and overexploitation of groundwater for irrigating the farmlands. Predictions of groundwater levels can help planners to deal with persistent water deficiencies. In this study, the support vector regression (SVR) and M5 decision tree models were used to predict the groundwater level in Ardebil plain. The monthly groundwater level data from 24 piezometers for a 17‐year period (1997 to 2013) were used for training and test of models. The model inputs included the groundwater levels of previous months, the volume of entering precipitation into every cell, and the discharge of wells. The model output was the groundwater level in the current month. In order to evaluate the performance of models, the correlation coefficient (R) and the root‐mean‐square error criteria were used. The results indicated that both SVR and M5 decision tree models performed well for the prediction of groundwater level in the Ardebil plain. However, the results obtained from the M5 decision tree model are more straightforward, more easily applied, and simpler to interpret than those from the SVR. The highest accuracy was obtained using the SVR model to predict the groundwater level from the Ghareh Hasanloo and Khalifeloo piezometers with R = 0.996 and R = 0.983, respectively.
Effects of high‐pressure homogenisation on structural and functional properties of mussel (Mytilus edulis) protein isolate
Authors: Yu Cuiping , Cha Yue , Wu Fan , Xu Xianbing , Qin Yuting , Li Xialin , Du Ming
Published: November 2017

In this study, the effects of high‐pressure homogenisation (HPH) treatment on structural and functional properties of mussel protein isolate (MPI) were investigated. HPH treatment did not modify the protein profiles of MPI, but caused changes in secondary, tertiary and quaternary structure. HPH treatment improved functional properties of MPI such as solubility, foaming ability, emulsifying activity and stability. This preliminary study demonstrated the potential of HPH technology to process MPI due to improving its functional properties.
Language barriers and their impact on provision of care to patients with limited English proficiency: Nurses' perspectives
Authors: Ali Parveen Azam , Watson Roger
Published: November 2017

Aim and objective

To explore nurses’ perspectives of language barriers and their impact on the provision of care to patients with limited English proficiency from diverse linguistic background.

Design and methods

A qualitative descriptive approach was used. Using individual interviews and focus group discussions, data were collected from 59 nurses working in tertiary care hospitals in England. A thematic analysis was used to analyse the data.

Findings

Three themes, “multi‐ethnicities and language barriers,” “the impact of language barriers” and “communicating via interpreters,” were identified. Communication was identified as the most important aspect of care provision and an essential component of a nurse's professional role regardless of the clinical area or speciality. Language barriers were identified as the biggest obstacles in providing adequate, appropriate, effective and timely care to patients with limited English proficiency. Use of professional interpreters was considered useful; however, the limitations associated with use of interpretation service, including arrangement difficulties, availability and accessibility of interpreters, convenience, confidentiality and privacy‐related issues and impact on the patient's comfort were mentioned.

Conclusions

Language barriers, in any country or setting, can negatively affect nurses’ ability to communicate effectively with their patients and thereby have a negative impact on the provision of appropriate, timely, safe and effective care to meet patient's needs.

Relevance to clinical practice

An understanding of language barriers can help nurses find appropriate strategies to overcome such barriers and, consequently, enhance the provision of effective care to patients affected by language barriers in any clinical setting in any healthcare system. The findings of the study have international relevance as language barriers affect healthcare provision in any country or setting.
The third person in the room: The needs of care partners of older people in home care services—A systematic review from a person‐centred perspective
Authors: Anker‐Hansen Camilla , Skovdahl Kirsti , McCormack Brendan , Tønnessen Siri
Published: November 2017

Aims and objectives

To identify and synthesise the needs of care partners of older people living at home with assistance from home care services.

Background

“Ageing in place” is a promoted concept where care partners and home care services play significant roles. Identifying the needs of care partners and finding systematic ways of meeting them can help care partners to cope with their role.

Design/methods

This study is based on the PRISMA reporting guidelines. The systematic review of qualitative and quantitative studies was guided by the Joanna Briggs Institute methodology.

Results

In total, 16 studies were included in the review, eleven qualitative and five quantitative. Three main categories were revealed in the analysis: the need for quality interaction, the need for a shared approach to care and the need to feel empowered.

Conclusion

Care partners of older people have several, continuously unmet needs. A person‐centred perspective can contribute new understandings of how to meet these needs. A knowledge gap has been identified regarding the needs of care partners of older people with mental health problems. There is a need to develop a tool for systematic collaboration between home care services and care partners, so that the identified needs can be met in a more thorough, systematic and person‐centred way.

Relevance to clinical practice

The carers in home care services need competence to identify and meet the needs of care partners. The implementation of person‐centred values in home care services can contribute to meet the needs of care partners to a greater extent than today. Future research on the needs of care partners of older people with mental health problems needs to be undertaken.
Clinical evaluation of the multifunctional suprapubic catheter in patients requiring permanent suprapubic cystostomy: A prospective randomised trial in a single centre
Authors: Dong Hai‐Jing , Lu Yi , Zhang Nian‐Zhao , Zhang Wen‐Hua , Wu Shuai , Zhao Hui , Zhang Chang‐Cun , Hou Si‐Chuan
Published: November 2017

Aims and objectives

To assess the clinical effect of the multifunctional suprapubic catheter (MSC) on occurrence of cystospasm, catheter occlusion, the catheter‐related urinary tract infection and remission of overactivity bladder, by comparing with the conventional suprapubic catheter (CSC) in patients with permanent suprapubic cystostomy.

Background

The conventional suprapubic catheter usually presents with high incidence of catheter‐associated complications.

Design

A prospective randomised clinical trial in a single centre.

Methods

Between January 2014 and January 2015, a total of 91 consecutive patients with permanent suprapubic cystostomy were prospectively randomised into two groups: the MSC group (n = 43) and CSC group (n = 48).

Results

Our results showed that the total times of cystospasm in the MSC group were significantly less than that in the CSC group during the follow‐up time (p < .001). In addition, the mean spasmodic duration per time in the MSC group was significantly shorter than that in the CSC group (p < .001). Besides, catheter occlusions were observed in 23 (25.27%) patients, including 5 (11.63%) in the MSC group and 18 (37.50%) in the CSC group (p = .005). The lower rate of positive urine culture was also found in the MSC group but with no significant difference (p = .540). Furthermore, the urodynamic measurement data demonstrated that the patients in the MSC group had a greater remission rate of overactivity bladder after catheter change (p < .001).

Conclusions

The present data showed that the multifunctional suprapubic catheter could significantly reduce the incidence of catheter occlusion, ameliorate the symptom of cystospasm and relieve the overactivity bladder, but have no influence on the catheter‐related urinary tract infection.

Relevance to clinical practice

The application of our self‐devised multifunctional suprapubic catheter may result in better management of the patients with permanent suprapubic cystostomy.
Increased severity of obstructive sleep apnea is associated with less anxiety and depression
Authors: Bjorvatn Bjørn , Rajakulendren Narvini , Lehmann Sverre , Pallesen Ståle
Published: November 2017

The objective was to investigate symptoms of depression and anxiety in relation to the presence and severity of obstructive sleep apnea (OSA) among patients referred with suspicion of OSA. The sample comprised 3770 consecutive patients with a mean age of 49.1 years; 69.7% were male. OSA was diagnosed and categorized based on a standard respiratory polygraphic sleep study using a type 3 portable monitor. Patients completed the validated Hospital Anxiety and Depression Scale (HADS) prior to the sleep study. In addition, they answered questions about whether they were currently in treatment for mental disorders and whether they had been diagnosed previously with depression. We adjusted for sex, age, smoking, alcohol consumption and obesity in the logistic regression analyses. In total, 35.1% had apnea–hypopnea index (AHI) < 5 (no OSA), 31.9% had AHI: 5–14.9 (mild OSA), 17.3% had AHI: 15–29.9 (moderate OSA) and 15.7% had AHI ≥ 30 (severe OSA). The prevalence of anxiety and depressive symptoms were significantly lower with increased OSA severity, and also when adjusting for sex, age, smoking, alcohol consumption and obesity (AHI ≥ 15 as dependent variable). Similarly, currently being in treatment for mental disorders and being diagnosed previously with depression were both associated negatively with OSA severity, with only the latter remaining significant in the fully adjusted model. Furthermore, multiple linear regressions showed that HADS anxiety and depression total scores were associated negatively with AHI. In conclusion, symptoms of anxiety and depression were associated negatively with OSA severity in these referred patients. The findings remained significant also after adjusting for several relevant confounders.
Knowledge regarding hepatitis B mother‐to‐child transmission among healthcare workers in South China
Authors: Chen Y. , Xie C. , Zhang Y. , Li Y. , Ehrhardt S. , Thio C. L. , Nelson K. E. , Chen Y. , Lin C.‐S.
Published: November 2017

To determine the knowledge regarding hepatitis B virus (HBV) mother‐to‐child transmission (MTCT) and its prevention and treatment among healthcare workers (HCWs) in Guangdong Province, China, an HBV endemic area. An HBV knowledge questionnaire was administered to 900 HCWs from the 3rd Affiliated Hospital of Sun Yat‐Sen University and 2 rural hospitals in Guangdong Province. The 27 items in the questionnaire fell into 3 sections: HBV MTCT general knowledge, respondents’ practices of preventing HBV MTCT and awareness of the resources of preventing HBV MTCT. The data collected were coded and analysed using SPSS software version 20. In total, 503 of 900 HCWs responded to the survey (response rate: 55.9%). Eighty‐four individuals responded correctly to all of the knowledge questions: 58 were doctors, and 26 were nurses (P < .05). Doctors more often performed practices than nurses (t = 3.591, P < .01). Participants from the infectious disease department demonstrated a significantly higher proportion of correct answers and resource utilization than other specialties (χ2 = 14.052, 7.998, P < .01). In terms of the average knowledge score, t test or ANOVA showed that there were significant differences between the specialty groups (t = 3.110, P < .01), hospital level groups (t = 2.337, P < .05) and age groups (F = 3.020, P < .05). Respondents’ initiative increased with hospital level and age (t = 2.993, 7.493, P < .01). A considerable percentage of HCWs has misconceptions about HBV MTCT. Healthcare workers, in particular nurses, those working in noninfectious disease departments or township hospitals and younger medical staff, lack systematic and comprehensive knowledge about HBV MTCT and are in urgent need of HBV‐related training.
Low incidence of hepatitis B virus reactivation and subsequent hepatitis in patients with chronic hepatitis C receiving direct‐acting antiviral therapy
Authors: Tamori A. , Abiru S. , Enomoto H. , Kioka K. , Korenaga M. , Tani J. , Enomoto M. , Sugiyama M. , Masaki T. , Kawada N. , Yatsuhashi H. , Nishiguchi S. , Mizokami M.
Published: November 2017

To determine the clinical characteristics of hepatitis B virus (HBV) reactivation in patients undergoing interferon‐free antihepatitis C virus (HCV) therapy, we examined HBV DNA in 25 HBV co‐infected patients and 765 patients with resolved HBV infection during and after treatment with direct‐acting antiviral agents (DAAs). Among those with HCV genotype 1, asunaprevir plus daclatasvir was administered to 160 patients, sofosbuvir (SOF) plus ledipasvir to 438 patients and paritaprevir plus ombitasvir and ritonavir to 25 patients. In total, 167 patients with genotype 2 were treated with SOF plus ribavirin. Three patients with an HBV DNA level ≥2000 IU/mL were treated with entecavir before anti‐HCV therapy, without reactivation of HBV. In 3 of 22 (12%) HBV surface antigen (HBsAg)‐positive patients with an HBV DNA level <2000 IU/mL, the viral load increased during treatment. However, hepatitis flare did not occur in these patients. There was no significant difference in clinical history between patients with and without HBV reactivation. Among 765 patients with resolved HBV infection, HBV reactivation occurred in 1 (0.1%) patient after initial resolution, whose HBV DNA level spontaneously decreased after DAA therapy. We compared anti‐HBs titres at baseline with those at post‐DAA therapy in 123 patients without HBsAg. There was no significant difference in anti‐HBs levels between the two points (P = .79). In conclusion, HBV reactivation was rare in HBsAg‐negative patients treated with DAA therapy. Additionally, hepatitis did not occur in HBV‐reactivated patients with a baseline HBV DNA level <2000 IU/mL before DAA therapy.
Independent signalling cues underpin arbuscular mycorrhizal symbiosis and large lateral root induction in rice
Authors: Chiu Chai Hao , Choi Jeongmin , Paszkowski Uta
Published: November 2017

Perception of arbuscular mycorrhizal fungi (AMF) triggers distinct plant signalling responses for parallel establishment of symbiosis and induction of lateral root formation. Rice receptor kinase CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) and α/β‐fold hydrolase DWARF14‐LIKE (D14L) are involved in pre‐symbiotic fungal perception.

After 6 wk post‐inoculation with Rhizophagus irregularis, root developmental responses, fungal colonization and transcriptional responses were monitored in two independent cerk1 null mutants; a deletion mutant lacking D14L, and with D14L complemented as well as their respective wild‐type cultivars (cv Nipponbare and Nihonmasari).

Here we show that although essential for symbiosis, D14L is dispensable for AMF‐induced root architectural modulation, which conversely relies on CERK1.

Our results demonstrate uncoupling of symbiosis and the symbiotic root developmental signalling during pre‐symbiosis with CERK1 required for AMF‐induced root architectural changes.
Molecular basis for immunohistochemical and inflammatory changes during progression of gingivitis to periodontitis
Authors: Kurgan Sivge , Kantarci Alpdogan
Published: November 2017

Two common diseases – gingivitis and periodontitis – affect the periodontium. Symptoms of disease entities are used for distinguishing various forms of gingivitis and periodontitis. Gingivitis follows a linear and progressive course when a healthy individual stops oral care, as shown by the experimental gingivitis model. It is not known if and when gingivitis transforms into periodontitis. A very limited number of studies present direct evidence regarding the histological changes over time and how they correlate to the clinical transition from gingivitis to periodontitis. This review focuses on the pathological changes that occur during the progression of gingivitis into periodontitis through discussing the molecular, cellular and immunohistochemical aspects of the inflammatory process. Molecular pathways regulating periodontal inflammation also determine the outcomes of disease and healing. Treatment of inflammatory diseases, particularly periodontitis in which extensive tissue damage could result from the inflammatory process, needs to target full restoration of the lost tissues. This can only be accomplished by a thorough understanding of the activation and resolution of periodontal disease and of the molecular events that occur during these phases.
Host modulation therapy with anti‐inflammatory agents
Authors: Preshaw Philip M.
Published: November 2017

Host modulation therapy refers to a treatment concept in which drug therapies are used as an adjunct to conventional periodontal treatment to ameliorate destructive aspects of the host inflammatory response. This strategy is not new in the treatment of periodontitis. Previously, nonsteroidal anti‐inflammatory drugs have been investigated in this regard, with evidence of reductions in alveolar bone resorption when these drugs are used for prolonged periods of time. However, the risk of significant unwanted effects precludes the use of both nonselective nonsteroidal anti‐inflammatory drugs and the selective cyclooxygenase‐2 inhibitors as adjunctive treatments for periodontitis. Currently, the only available adjunctive host response modulator that is licensed for the treatment of periodontitis is subantimicrobial dose doxycycline, which functions as an inhibitor of matrix metalloproteinases. Although clinical benefits have been shown in carefully conducted randomized controlled trials, the efficacy of subantimicrobial dose doxycycline in routine clinical practice has yet to be determined. Anti‐cytokine therapies have been developed for use in the treatment of rheumatoid arthritis, the pathogenesis of which bears many similarities to that of periodontitis; however, the significant risk of unwanted effects (as well as cost and lack of human trials in the treatment of periodontal diseases) precludes the use of any of the currently available anti‐cytokine therapies in the treatment of periodontitis. The identification of pro‐resolving lipid mediators as well as small molecule biologicals that influence inflammatory responses offers the best potential, at the present time, for the development of novel host response modulators in periodontal therapy, but much research remains to be done to confirm safety and efficacy.
Internal Combustion Engines as Fluidized Bed Reactors
Authors: Lavrich Zoe , Taie Zachary , Menon Shyam , Daly Shane , Halliday Devin , Hagen Chris
Published: November 2017

An internal combustion engine which is primarily designed for producing power can be utilized as a chemical reactor for a range of chemical processes given its inherent advantages including high throughput, high chemical conversion efficiency, and reactant/product handling benefits. For gas-phase processes requiring a catalyst, the ability to develop a fluidized bed reactor within the engine cylinder would greatly enhance gas/solid mixing, reducing mass transfer barriers and allowing the reactor to efficiently process large volumes of fluid. In addition, use of an engine could facilitate vibration and pulsed flow which may enhance fluidization quality. This work examines the fluidization behavior of particles within a cylinder of an internal combustion engine at various engine speeds using analytical and experimental methods. First, calculations were carried out to determine the maximum fluidization velocity and the corresponding engine speeds below which fluidization of a particle bed is possible given the properties of the particles and engine dimensions. Fluidization depends on particle properties as well as the engine used. For 40–63 micron diameter silica gel particles placed inside a modified Megatech Mark III transparent combustion engine (with a bore of 4.1 cm, stroke length of 5.1 cm and compression ratio of 2.4), calculations indicate that engine speeds of approximately 1.1 to 60.8 RPM would result in fluidization of the particles. For higher engine speeds, the fluidization behavior is expected to deteriorate as the maximum fluidization velocity is surpassed. Next, experiments were conducted using the transparent engine and video recording to obtain qualitative confirmation of the analytical predictions. Simulations were then performed using ANSYS Fluent to investigate pressure drop across the bed. Consistent with the calculations, for an engine speed of 48 RPM, fluidized behavior was observed. In contrast for an engine speed of 171 RPM, the fluidization was observed to deteriorate and result in a “cake” of particles that moved in a lumped manner. Overall, the investigation shows that a fluidized bed can be obtained within the cylinder of a reciprocating piston engine if the engine speed is within the range predicted by the maximum fluidization velocity.
1.25 L Turbocharged Diesel for Demanding Non-Road Applications
Authors: Sykes David M. , Carpenter Andrew L. , Wagner Jerald G. , Gattoni John M. , Merical Kyle I. , Yelvington Paul E.
Published: November 2017

A design process was defined and implemented for the rapid development of purpose-built, heavy-fueled engines using modern CAE tools. The first exercise of the process was the clean sheet design of the 1.25 L, three-cylinder, turbocharged AMD45 diesel engine. The goal of the AMD45 development program was to create an engine with the power density of an automotive engine and the durability of an industrial/military diesel engine. The AMD45 engine was designed to withstand 8000 hours of operation at 4500 RPM and 45 kW output, while weighing less than 100 kg. Using a small design team, the total development time to a working prototype was less than 15 months.

Following the design phase, the AMD45 was fabricated and assembled for first prototype testing. The minimum-material-added design approach resulted in a lightweight engine with a dry weight 89 kg for the basic engine with fuel system. At 4500 RPM and an intake manifold pressure of 2.2 bar abs., the AMD45 produced 62 kW with a peak brake fuel-conversion efficiency greater than 34%. Predictions of brake power and efficiency from the design phase matched to within 5% of experimental values. When the engine is detuned to 56 kW maximum power, the use of multi-pulse injection and boost pressure control allowed the AMD45 to achieve steady state emissions (as measured over the ISO 8178 C1 test cycle) of CO and NOx+NMHC that met the EPA Tier 4 Non-road standard without exhaust after-treatment, with the exception of idle testing. PM emissions were also measured, and a sulfur-tolerant diesel particulate filter has been designed for PM after-treatment.
Poison Build-up and Performance Degradation of an Oxidation Catalyst in 2-Stroke Natural Gas Engine Exhaust
Authors: Baumgardner Marc E. , Olsen Daniel B.
Published: November 2017

Due to current and future exhaust emissions regulations, oxidation catalysts are increasingly being added to the exhaust streams of large-bore, 2-stroke, natural gas engines. Such catalysts have been found to have a limited operational lifetime, primarily due to chemical (i.e. catalyst poisoning) and mechanical fouling resulting from the carry-over of lubrication oil from the cylinders. It is critical for users and catalyst developers to understand the nature and rate of catalyst deactivation under these circumstances. This study examines the degradation of an exhaust oxidation catalyst on a large-bore, 2-stroke, lean-burn, natural gas field engine over the course of 2 years. Specifically this work examines the process by which the catalyst was aged and tested and presents a timeline of catalyst degradation under commercially relevant circumstances. The catalyst was aged in the field for 2 month intervals in the exhaust slipstream of a GMVH-12 engine and intermittently brought back to the Colorado State Engines and Energy Conversion Laboratory for both engine testing and catalyst surface analysis. Engine testing consisted of measuring catalyst reduction efficiency as a function of temperature as well as the determination of the light-off temperature for several exhaust components. The catalyst surface was analyzed via SEM/EDS and XPS techniques to examine the location and rate of poison deposition. After 2 years on-line the catalyst light-off temperature had increased ∼55°F (31°C) and ∼34 wt% poisons (S, P, Zn) were built up on the catalyst surface, both of which represent significant catalyst deactivation.
Durability Testing of Biomass Based Oxygenated Fuel Components in a Compression Ignition Engine
Authors: Baumgardner Marc E. , Lakshminarayanan Arunachalam , Olsen Daniel B. , Ratcliff Matthew A. , McCormick Robert L. , Marchese Anthony J.
Published: November 2017

Blending cellulosic biofuels with traditional petroleum-derived fuels results in transportation fuels with reduced carbon footprints. Many cellulosic fuels rely on processing methods that produce mixtures of oxygenates which must be upgraded before blending with traditional fuels. Complete oxygenate removal is energy-intensive and it is likely that such biofuel blends will necessarily contain some oxygen content to be economically viable. Previous work by our group indicated that diesel fuel blends with low levels (<4%-vol) of oxygenates resulted in minimal negative effects on short-term engine performance and emissions. However, little is known about the long-term effects of these compounds on engine durability issues such as the impact on fuel injection, in-cylinder carbon buildup, and engine oil degradation. In this study, four of the oxygenated components previously tested were blended at 4%-vol in diesel fuel and tested with a durability protocol devised for this work consisting of 200 hrs of testing in a stationary, single-cylinder, Yanmar diesel engine operating at constant load. Oil samples, injector spray patterns, and carbon buildup from the injector and cylinder surfaces were analyzed. It was found that, at the levels tested, these fuels had minimal impact on the overall engine operation, which is consistent with our previous findings.
Effect of the Diffuser on Diesel Turbocharger Compressor Performance and Noise Emission
Authors: Chen Liu , Yipeng Cao , Wenping Zhang
Published: November 2017

The effect of diffuser on compressor performance and noise emission is studied in this paper. Firstly, on the basis of the mature compressor model, the airflow geometry from impeller inlet to volute exit has been simulated numerically. Then, the number of diffuser blade is changed and the impeller blade number remains unchanged. The effects of different diffuser blade number on compressor performance at three different compressor operating lines were analyzed and noise emission has been investigated at selected compressor operating point. It is found that flow range narrows down with blade number increase but there are pressure and efficiency enhancement at maximum efficiency working range with specific blade number. The noise simulation results show that there has the best stator blade number when the impeller blade unchanged. Moreover, a special kind of technique that called pinched diffuser is investigated in this paper. The results of four different pinch constructions indicate that the pinched diffuser can shift the surge line to low flow rates but the pressure passing through centrifugal compressor has decreased at the same time, small pinch is conducive to noise reduction which means there is also an optional structure that can obtain minimum noise, which means a more reasonable pinched construction design should be studied to improve the compressor performance and control the radiated noise.
Reaction of Sulfuric Acid in Lube Oil: Implications for Large Two-Stroke Diesel Engines
Authors: Lejre Kasper H. , Kiil Søren , Glarborg Peter , Christensen Henrik , Mayer Stefan
Published: November 2017

Slow-steaming operation and an increased pressure in the combustion chamber have contributed to increased sulfuric acid (H2SO4) condensation on the cylinder liners in large two-stroke marine diesel engines, thus causing increased corrosion wear. To cope with this, lube oils are formulated with overbased detergent additives present as CaCO3 reverse micelles to neutralize the condensing H2SO4. In this present work, a mixed flow reactor (MFR) setup aims to investigate the neutralization reaction by varying Ca/S molar ratio, stirrer speed, H2SO4 inlet concentration, and residence time. Lube oil samples from the outlet of the MFR were analysed by use of Fourier Transform Infrared Spectroscopy (FTIR) and a titration method. The MFR results indicate that the CaCO3-H2SO4 reaction is very fast in a real engine, if the cylinder liner is well-wetted, the oil-film is well-mixed, and contains excess of CaCO3 compared to the condensed H2SO4. The observed corrosion wear in large two-stroke marine diesel engines could consequently be attributed to local molar excess of H2SO4 compared to CaCO3 reverse micelles on the cylinder liners.
Combustion Performance and Unburned Hydrocarbon Emissions of a Natural Gas–Diesel Dual Fuel Engine at a Low Load Condition
Authors: Guo Hongsheng , Liko Brian , Luque Luis , Littlejohns Jennifer
Published: November 2017

The combustion of natural gas reduces fuel cost and generates less emissions of carbon dioxide and particulate matter than diesel and gasoline. Replacing diesel by natural gas in internal combustion engines is of great interest for transportation and stationary power generation. Dual fuel combustion is an efficient way to burn natural gas in internal combustion engines.

In natural gas–diesel dual fuel engines, unburned hydrocarbon emissions increase with increasing natural gas fraction. Many studies have been conducted to improve the performance of natural gas–diesel dual fuel engines and reported the performance of combustion and emissions of regulated pollutants and total unburned hydrocarbon at various engine operating strategies. However, little has been reported on the emissions of different unburned hydrocarbon components. In this paper, an experimental investigation was conducted to investigate the combustion performance and emissions of various unburned hydrocarbon components, including methane, ethane, ethylene, acetylene, propylene, formaldehyde, acetaldehyde and benzaldehyde, at a low engine load condition. The operating conditions, such as engine speed, load, intake temperature and pressure, were well controlled during the experiment. The combustion and emissions performance of pure diesel and natural gas–diesel dual fuel combustion were compared. The effect of diesel injection timing was analyzed. The results show that appropriately advancing diesel injection timing to form a homogeneous charge compression ignition-like combustion is beneficial to natural gas–diesel dual fuel combustion at low load conditions. The emissions of different unburned hydrocarbon components changed in dual fuel combustion, with emissions of some unburned hydrocarbon components being primarily due to the combustion of natural gas, while those of others being more related to diesel combustion.
Numerical Prediction of CCV in a PFI Engine Using a Parallel LES Approach
Authors: Ameen Muhsin M. , Mirzaeian Mohsen , Millo Federico , Som Sibendu
Published: November 2017

Cycle-to-cycle variability (CCV) is detrimental to IC engine operation and can lead to partial burn, misfire, and knock. Predicting CCV numerically is extremely challenging due to two key reasons. Firstly, high-fidelity methods such as large eddy simulation (LES) are required to accurately resolve the in-cylinder turbulent flowfield both spatially and temporally. Secondly, CCV is experienced over long timescales and hence the simulations need to be performed for hundreds of consecutive cycles. Ameen et al. (Int. J. Eng. Res., 2017) developed a parallel perturbation model (PPM) approach to dissociate this long time-scale problem into several shorter time-scale problems. The strategy is to perform multiple single-cycle simulations in parallel by effectively perturbing the initial velocity field based on the intensity of the in-cylinder turbulence. This strategy was demonstrated for motored engine and it was shown that the mean and variance of the in-cylinder flowfield was captured reasonably well by this approach. In the present study, this PPM approach is extended to simulate the CCV in a fired port-fuel injected (PFI) spark ignition (SI) engine. Two operating conditions are considered — a medium CCV operating case corresponding to 2500 rpm and 16 bar BMEP and a low CCV case corresponding to 4000 rpm and 12 bar BMEP. The predictions from this approach are also shown to be similar to the consecutive LES cycles. Both the consecutive and PPM LES cycles are observed to under-predict the variability in the early stage of combustion. The parallel approach slightly under-predicts the cyclic variability at all stages of combustion as compared to the consecutive LES cycles. However, it is shown that the parallel approach is able to predict the coefficient of variation (COV) of the in-cylinder pressure and burn rate related parameters with sufficient accuracy, and is also able to predict the qualitative trends in CCV with changing operating conditions. The convergence of the statistics predicted by the PPM approach with respect to the number of consecutive cycles required for each parallel simulation is also investigated. It is shown that this new approach is able to give accurate predictions of the CCV in fired engines in less than one-tenth of the time required for the conventional approach of simulating consecutive engine cycles.
EGR and Backpressure Effects on Knock Behavior in Stoichiometric Natural Gas Engines
Authors: Williams D. Ryan , Knutzen Henry , Chiera Domenico , Hampson Gregory J.
Published: November 2017

Increasingly restrictive limits on NOx levels are driving the change from lean-burn to stoichiometric combustion strategies on heavy-duty on-highway natural gas engines in order to take advantage of inexpensive and effective three-way catalyst technology. The change to stoichiometric combustion has led to increased tendency for engine knock due to higher in-cylinder temperatures. Exhaust Gas Recirculation (EGR) has been proposed as a method to suppress knock via charge dilution while maintaining a stoichiometric air-fuel ratio. Two of the more common EGR driving architectures and the challenges associated with each architecture are described.

A series of engine tests were devised and performed on a 7-liter heavy-duty natural gas engine to explore the relationships between EGR knock suppression and engine backpressure. A unique concept for an external EGR pumping cart which allowed for the exploration of higher EGR rates independent of backpressure is also described. Results showed that for the conditions tested, increasing EGR rates beyond a certain point did not result in decreased knock tendency. 1D Simulation showed that the effectiveness of the EGR is limited by trapped hot residual gasses which resulted in higher in-cylinder temperatures and nullified the cooling effects of the EGR. These results suggest that attention must be paid to reducing backpressure via efficient EGR system architecture design in order to achieve the highest possible efficiency.
Combustion and Emissions of Jet-A and N-Butanol in RCCI Operation
Authors: Soloiu Valentin , Moncada Jose , Gaubert Remi , Harp Spencer , Flowers Kyle , Ilie Marcel
Published: November 2017

Jet-A was investigated in RCCI (Reactivity Controlled Compression Ignition) given that the fuel is readily available and has a similar cetane number compared to ultra-low sulfur diesel (ULSD#2). To promote emissions’ control, RCCI was conducted with direct injection (DI) of Jet-A and PFI (port fuel injection) of n-butanol. Combustion and emission characteristics of Jet-A RCCI were investigated for a medium duty DI experimental engine operated at constant boost and 30% EGR rate and compared to ULSD#2 RCCI and single-fuel ULSD#2 operation. DI fuel was injected at 5 CAD ATDC and constant rail pressure of 1500 bar. A 20% pilot by mass was added and investigated at timings from 15 to 5 CAD BTDC for combustion stability. The results showed that the effect of the pilot injection on Jet-A combustion was not as prominent as compared to that of ULSD#2, suggesting a slightly different spray and mixture formation. Ignition delay for Jet-A was 15–20% shorter compared to ULSD#2 in RCCI. When the pilot was set to 5 CAD BTDC, CA50 phased for ULSD#2 RCCI by 3 CAD later when compared to Jet-A RCCI. After TDC, the local pressure maximum for ULSD#2 RCCI decreased by 3 bar, resulting from a 15% difference in peak heat release rate between ULSD#2 and Jet-A in RCCI at the same pilot timing. NOx and soot levels were reduced by a respective maximum of 35% and 80% simultaneously in Jet-A RCCI mode compared to single-fuel ULSD#2, yet, were higher compared to ULSD#2 RCCI. Ringing intensity was maintained at similar levels and energy specific fuel consumption (ESFC) improved by at least 15% for Jet-A compared to ULSD#2 in RCCI. Mechanical efficiencies additionally improved at earlier pilot timing by 2%. In summary, Jet-A RCCI allowed for emissions control and increased fuel efficiencies compared to single fuel ULSD#2, however, injection should be further tweaked in order to reach lower soot levels.
Decentralized Feedback Control of Pumping Losses and NOx Emissions in Diesel Engines
Authors: Salehi Rasoul , Martz Jason , Stefanopoulou Anna , Vernham Bruce , Uppalapati Lakshmidhar , Baliga Bantwal Prashant
Published: November 2017

A novel decentralized control architecture is developed based on a feedback from the pressure difference across the engine which is responsible for the pumping losses and the Exhaust Gas Recirculation (EGR) flow in diesel engines. The controller is supplemented with another feedback loop based on NOx emissions measurement. Aiming for simple design and tuning, the two control loops are designed and discussed; one manipulates the Variable Geometry Turbine (VGT) actuator and the other manipulates the EGR valve. An experimentally validated mean-value diesel engine model is used to analyze the best pairing of actuators and set points. Emphasis is given to the robustness of this pairing based on gain changes across the entire operating region, since swapping the pairing needs to be avoided. The VGT loop is designed to achieve fast cylinder air charge increase in response to a rapid pedal tip-in by a feedforward term based on the real-time derivative of the desired boost pressure. The EGR loop relies on a feedback measurement from a NOx sensor and a real-time estimation of cylinder oxygen ratio, χcyl. The engine model is used for evaluating the designed controllers over the federal test procedure (FTP) for heavy duty vehicles. Results indicate that the control system meets all targets, namely fast air charge and χcyl control during torque transients, robust NOx control during steady state operation and controlled pumping losses in all conditions.
Influence of Acetone-Butanol-Ethanol (ABE)–Gasoline Blends on Regulated and Unregulated Emissions From a PFI SI Engine
Authors: Li Yuanxu , Nithyanandan Karthik , Gao Suya , Ning Zhi , Lee Chia-fon F.
Published: November 2017

Bio-butanol has been widely investigated as a promising alternative fuel. However, the main issues preventing industrial-scale production of butanol are its relatively low production efficiency and high cost of component recovery from the acetone-butanol-ethanol (ABE) fermentation process. Therefore, ABE has attracted a lot of interest as an alternative fuel for the reason that it not only has positive characteristics of oxygenated fuels, but also reduces the production cost during fermentation. This investigation is focused on the regulated and unregulated emissions of a single cylinder port-fuel injection (PFI) spark-ignition (SI) engine fueled with ABE (volumetric concentration of A:B:E = 3:6:1) and gasoline blends. Blends of gasoline with various ABE content (0 vol.%, 10 vol.%, 20 vol.% ABE referred to as G100, ABE10, ABE20) were used as test fuels. Experiments were performed at an engine speed of 1200 rpm, and at engine loads of 3 and 5 bar brake mean effective pressures (BMEP) and under various equivalence ratios (Φ = 0.83–1.25). Exhaust gases measured included nitrogen oxides (NOX), carbon monoxide (CO) and unburned hydrocarbons (UHC). Additionally, benzene, ethylbenzene, toluene and xylenes (BTEX) concentrations were also measured by a gas chromatograph coupled with a mass spectrometer (GC/MS) and a flame ionization detection (GC/FID). The results show that with an increase of ABE in the blended fuel, there are reductions of UHC, CO and NOx. For the unregulated emissions, ABE addition leads to decreases in benzene, toluene and xylene emissions but an increase in ethylbenzene.
Synthetic transcription elongation factors license transcription across repressive chromatin
Authors: Erwin Graham S. , Grieshop Matthew P. , Ali Asfa , Qi Jun , Lawlor Matthew , Kumar Deepak , Ahmad Istaq , McNally Anna , Teider Natalia , Worringer Katie , Sivasankaran Rajeev , Syed Deeba N. , Eguchi Asuka , Ashraf Md. , Jeffery Justin , Xu Mousheng , Park Paul M. C. , Mukhtar Hasan , Srivastava Achal K. , Faruq Mohammed , Bradner James E. , Ansari Aseem Z.
Published: November 2017

Chemical control of transcription

Friedreich's ataxia, a devastating neurodegenerative disease with no effective therapy, is caused by an expansion of intronic repeats and hence a reduced expression of the
FXN
gene. Erwin
et al.
synthesized a molecule that specifically targets the expanded repressive repeats. This molecule thereby licenses productive transcription elongation and restores
FXN
expression to normal levels. In the future, similar interventions may be effective in a diverse array of diseases caused by unstable expansions in microsatellite repeats.

Science
, this issue p.
1617
Poly[
n
]catenanes: Synthesis of molecular interlocked chains
Authors: Wu Qiong , Rauscher Phillip M. , Lang Xiaolong , Wojtecki Rudy J. , de Pablo Juan J. , Hore Michael J. A. , Rowan Stuart J.
Published: November 2017

A little zinc makes the rings all link

Although polymer strands are often informally called chains, molecular topologies that actually resemble extended macroscopic chain links have proven surprisingly challenging to make. Most approaches have settled for tethering pairs of interlocked rings amid spacer segments. Wu
et al.
now report successful synthesis of polycatenanes in which tens of rings are consecutively interlinked. The key was using zinc ions to template the threading of one macrocycle precursor through flanking preformed macrocycles, after which metathesis catalysis closed up the first ring, and the metal could be flushed out.

Science
, this issue p.
1434
Clinical factors associated with syphilis concordance in men in sexual partnerships: a cross-sectional couples study
Authors: Towns Janet M , Huffam Sarah , Chow Eric P F , Denham Ian , Zhang Lei , Ryan Andrea , Bellhouse Clare Elizabeth , Bissessor Melanie , Bradshaw Catriona S , Phillips Tiffany , Graves Stephen , Fairley Christopher K , Chen Marcus Y
Published: November 2017

Background

Syphilis infections continue to increase among men who have sex with men (MSM) in many countries, with rates often higher among HIV-positive MSM. There is limited understanding of the risk and determinants of syphilis transmission between men. We aimed to examine the concordance of early syphilis infection between male sexual partners and clinical factors associated with transmission.

Methods

Men attending Melbourne Sexual Health Centre with their male partners, where at least one was diagnosed with early syphilis, were identified from linkage of partner records between March 2011 and April 2016. Early latent syphilis was defined as a new asymptomatic syphilis presentation of less than 2 years’ duration. Associations between concordance and potential risk factors were examined using Fisher’s exact test.

Results

Among 43 couples (86 men) identified, there were 13 couples (26 men) where both were diagnosed with early syphilis, representing a concordance rate of 30.2% (95% CI 17.2% to 46.1%). Among the 13 concordant couples, 5 men had primary syphilis (4 penile, 1 anal), 11 secondary syphilis (8 generalised rash, 3 penile, 2 anal, 1 oral lesion) and 10 early latent infections. Concordance was higher among couples where at least one partner had secondary syphilis compared with couples where neither partner had secondary syphilis (53% (9/17) vs 15% (4/26), P=0.016). Furthermore, concordance was higher among couples where one was HIV positive compared with couples where both were HIV negative (62% (5/8) vs 23% (8/35), P=0.042).

Conclusions

There was an overall concordance rate of 30%. Higher concordance rates for early syphilis infection between male sexual partners were associated with HIV and secondary syphilis.
George Rafferty
Authors: Richards Kate
Published: November 2017

A well‐respected, understanding veterinary surgeon who was as comfortable with his clients as with the many species of animals he treated. He was Deputy Lord Lieutenant for Inverness‐shire and was awarded an MBE for his services to agriculture.