bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral vasculitis presenting as a stroke
Authors: Montefort Maxine , Dashora Umesh , Chowdhury Muhammad
Published: November 2012

A 57-year-old man was admitted with right arm weakness and numbness on the background of intermittent headaches. On examination he was found to have mildly decreased sensation, power was 4/5 on the right side. He had dyspraxia in the right hand and was unable to spell his name. His speech was hesitant and he had left-sided visual field impairment as well as some photophobia. MRI and CT revealed multiple areas of haemorrhage and infarctions raising the possibility of primary angitis of brain. The biopsy confirmed the diagnosis. The patient responded to steroids and immunosuppressants partially.
A unique presentation of four thrombotic events at a time
Authors: Rajani Ali Raza , Hussain Kosar , Baslaib Fahad Omar , Radaideh Ghazi Ahmad
Published: November 2012

A 72-year-old man was referred to our hospital as a case of postcardiac arrest following a long distance air flight. Work-up in the emergency department revealed the presence of deep vein thrombosis (DVT), bilateral pulmonary embolism, inferior STEMI (ST elevation myocardial infarction) and ischaemic stroke. He received thrombolysis by recombinant tissue plasminogen activator (tPA) following which his haemodynamic status improved, but he developed haemorrhagic transformation of the stroke as a complication. The haemorrhagic lesion gradually resolved with conservative management, leaving behind a residual neurological deficit. His haemodynamic status was stable after the management. Although a diagnosis of right-to-left shunt lesion was highly suggestive in this condition, it could not be confirmed on the transthoracic echocardiogram.  Our patient had a unique presentation of multiple thrombi in different organs that caused significant morbidity and haemodynamic instability. There are no well-established guidelines that discuss the acute management of such cases. This situation requires a careful assessment and management of the patient by a multidisciplinary team.
Choledocholithiasis presenting with very high transaminase level
Authors: Agahi Amy , McNair Alistair
Published: November 2012

We present three cases of choledocholithiasis presenting with a rise in transaminase to levels normally associated with acute hepatitis (alanine aminotransferase in excess of 1000 IU/l). All three cases had repeated investigation for liver disease before identification of common bile duct stones with magnetic resonance cholangiopancreatogram, and removal at endoscopic retrograde cholangiopancreatogram. We discuss the existing literature and the potential mechanisms of hepatocyte injury in extrahepatic obstruction.
Chronic contained aortic rupture presenting as anterior thigh pain
Authors: Keller Andrew
Published: November 2012

An 83-year-old man presented with severe left anterolateral thigh and knee pain for several days. He was completely unable to ambulate owing to the pain. The patient reported no history of acute back pain prior to presentation. His history initially confounded diagnosis. Subsequent investigations demonstrated a chronic contained rupture of an infrarenal aortic aneurysm with significant vertebral body erosion and obliteration of the ipsilateral psoas muscle. Proposed symptomatology was compression of the lateral femoral cutaneous nerve and its roots. The patient had multiple medical comorbidities and died of unrelated causes before his aneurysm was able to be repaired.
A bolt from the blew: rhinolith in the nose for more than 80 years
Authors: Kermanshahi Mohammad Shebli , Jassar Patrick
Published: November 2012

Rhinoliths are calcareous concretions that are formed by the deposition of salts on an intranasal foreign body over a number of years. We describe a rare case of rhinolithiasis, whereby a small foreign body has been lodged in a man's nasal cavity for over 80 years. He presented to the ear, nose and throat clinic with a sore throat and an incidental finding of a rhinolith was made which was confirmed by x-ray. This was managed conservatively.
Herniation of the liver via an incisional abdominal wall defect
Authors: Warbrick-Smith James , Chana Prem , Hewes James
Published: November 2012

Herniation of the liver through an anterior abdominal wall incisional defect has rarely been described. An 81-year-old man presented to our surgical team with acute right upper quadrant abdominal pain. He had undergone coronary artery bypass grafting via a median sternotomy 7 years previously. Examination revealed gallbladder tenderness and a non-tender incisional epigastric hernia. Cholecystitis was confirmed on ultrasound. A CT scan revealed a knuckle of liver (segment II/III) herniating through an upper midline anterior abdominal wall incisional defect.
Is blinking of the eyes affected in extrapyramidal disorders? An interesting observation in a patient with Wilson disease
Authors: Verma Rajesh , Lalla Rakesh , Patil Tushar B
Published: November 2012

Blinking of eye is a routine human activity which seldom attracts any attention of clinicians in health and disease. There is experimental evidence that blink rate is affected in extrapyramidal disorders affecting the balance of these neurotransmitters. However, no observations regarding blink rate in Wilson disease (WD) have been reported previously. We report a patient of WD with an increased spontaneous blink rate. A 24-year-old lady presented complaining of tremulousness of both upper limbs and head for 2 years, dysphagia and difficulty in speaking for 1.5 years and abnormal behaviour for last 1 year. We observed that her blink rate at rest was 32/min. Serum ceruloplasmin level was low (0.08 g/l). The patient was started on therapy withd-penicillamine, zinc sulphate, levodopa-carbidopa and trihexiphenidyl. At 1-month follow-up, patient's tremors were markedly decreased and blink rate at rest was decreased to 12/min.
Devastating coagulase-negative staphylococcal septicaemia in an extremely low birth weight infant
Authors: Samarasekara Sujeevan Indunil , Booth David , Clarke Paul
Published: November 2012

In developed countries, coagulase-negative staphylococci (CoNS) are responsible for the majority of late-onset infections in very low birth weight infants undergoing neonatal intensive care. As a common skin commensal, they are often considered as mere contaminants of peripheral blood cultures or as relatively benign bacteria clinically. We present a case of invasive CoNS septicaemia in an extremely low birth weight infant which had devastating effects.
Overlap syndrome: a diagnostic dilemma
Authors: Shah Kaushal Mahendra , Kanitkar Sampada
Published: November 2012

We report an interesting case of a young patient who came with a concern for missing teeth and lack of hair on scalp and body. Examination revealed complete absence of teeth, absence of eyebrows, eyelashes and hair over scalp. He was short-statured, had hyperextensible joints and hyperelastic skin, protuberant lips and many other anomalies such that the overall pattern of defects was not recognisable. A wide array of investigations involving the dental and medical faculties were done; however, the final diagnosis could not be reached, since it appeared to involve features of more than one syndrome, thus the name ‘overlap syndrome’.
Good's syndrome and IgA monoclonal gammopathy of undetermined significance
Authors: Oehler Erwan , Heuberger Laurence , Ghawche Frédéric , Valour Florent
Published: November 2012

Characterised by the association of a thymoma, hypogammaglobulinaemia, and B-cell and T-cell dysfunction, Good's syndrome (GS) is a rare cause of adult immunodeficiency leading to recurrent infections, and autoimmune manifestations related to the thymoma. We describe a 70-year-old woman in whom the diagnosis of GS was made after 7 years follow-up of a monoclonal gammopathy of undetermined significance (MGUS). After thymectomy, she received monthly intravenous immunoglobulin perfusions in order to maintain a normal plasmatic IgG level. To our knowledge, this is the fifth described case of GS associated with an MGUS. This rare condition should not be misdiagnosed, as the prognosis is determined by infectious and autoimmune complications, which could be prevented.
Healthcare professionals’ and mothers’ knowledge of, attitudes to and experiences with, Baby-Led Weaning: a content analysis study
Authors: Cameron Sonya Lynne , Heath Anne-Louise Mary , Taylor Rachael Waring
Published: November 2012

Objective

Baby-Led Weaning (BLW) is an alternative approach for introducing complementary foods to infants that emphasises infant self-feeding rather than adult spoon-feeding. Here we examined healthcare professionals’ and mothers’ knowledge of, attitudes to and experiences with, BLW.

Design, setting and participants

Healthcare professionals (n=31) and mothers who had used BLW (n=20) completed a semistructured interview using one of two tailored interview schedules examining their knowledge of, attitudes to and experiences with, BLW. Interview notes and transcripts were analysed using content analysis to identify subcategories and extract illustrative quotes.

Results

Healthcare professionals had limited direct experience with BLW and the main concerns raised were the potential for increased risk of choking, iron deficiency and inadequate energy intake. Although they suggested a number of potential benefits of BLW (greater opportunity for shared family meal times, fewer mealtime battles, healthier eating behaviours, greater convenience and possible developmental advantages) most felt reluctant to recommend BLW because of their concern about the potential increased risk of choking. In contrast, mothers who had used this style of feeding reported no major concerns with BLW. They considered BLW to be a healthier, more convenient and less stressful way to introduce complementary foods to their infant and recommended this feeding approach to other mothers. Although mothers did not report being concerned about choking, 30% reported at least one choking episode—most commonly with raw apple.

Conclusions

Given the lack of research on BLW, further work is needed to determine whether the concerns expressed by healthcare professionals and potential benefits outlined by mothers are valid. The current study suggests that there is a mismatch between healthcare professionals' and mothers’ knowledge of, attitudes to and experiences, with BLW.
Heart rate and systolic blood pressure in patients with minor to moderate, non-haemorrhagic injury versus normal controls
Authors: Bruijns Stevan Raynier , Guly Henry R , Bouamra Omar , Lecky Fiona , Wallis Lee A
Published: November 2012

Background

Raised blood pressure (and heart rate (HR)) due to anxiety in a clinical situation is well described and is called the white coat effect (WCE). It is not known whether the pain and anxiety that results from trauma causes a measurable WCE.

Methods

A sample of patients with a non-haemorrhagic injury from the Trauma Audit and Research Network (TARN) was compared with a healthy, non-injury sample from the Health Survey for England (HSE) databases. Two-way analysis of variance with rank transformation of data was used to compare systolic blood pressure (SBP) and HR between the groups at different ages. In the injured group, the SBP and HR were also compared between spinally immobilised and non-immobilised patients.

Results

There was a statistically significant difference between the groups for both HR and SBP (p<0.001). Median HR remained approximately 10 bpm higher in the TARN set when compared to the HSE set, irrespective of age. The difference for SBP was not considered clinically relevant (the highest was 5 mm Hg). There was no significant difference between immobilised and non-immobilised patients, for either HR or SBP (p=0.07 and 0.3, respectively).

Discussion

Median HR remained approximately 10 bpm higher in the TARN (injury) set compared to the HSE (non-injury, control) set, irrespective of age. Understanding that HR reacts in this way for mild to moderately injured patients is important as it will affect clinical interpretation during the initial assessment.
Ambulance demand: random events or predicable patterns?
Authors: Cantwell Kate , Dietze Paul , Morgans Amee E , Smith Karen
Published: November 2012

Background

Occupational, social and recreational routines follow temporal patterns, as does the onset of certain acute medical diseases and injuries. It is not known if the temporal nature of injury and disease transfers into patterns that can be observed in ambulance demand. This review examines eligible study findings that reported temporal (time of day, day of week and seasonal) patterns in ambulance demand.

Methods

Electronic searches of Medline and Cumulative Index of Nursing and Allied Health Literature were conducted for papers published between 1980 and 2011. In addition, hand searching was conducted for unpublished government and ambulance service documents and reports for the same period.

Results

38 studies examined temporal patterns in ambulance demand. Six studies reported trends in overall workload and 32 studies reported trends in a subset of ambulance demand, either as a specific case type or demographic group. Temporal patterns in overall demand were consistent between jurisdictions for time of day but varied for day of week and season. When analysed by case type, all jurisdictions reported similar time of day patterns, most jurisdictions had similar day of week patterns except for out-of-hospital cardiac arrest and similar seasonal patterns, except for trauma. Temporal patterns in case types were influenced by age and gender.

Conclusions

Temporal patterns are present in ambulance demand and importantly these populations are distinct from those found in hospital datasets suggesting that variation in ambulance demand should not be inferred from hospital data alone. Case types seem to have similar temporal patterns across jurisdictions; thus, research where demand is broken down into case types would be generalisable to many ambulance services. This type of research can lead to improvements in ambulance service deliverables.
External validation of the Cardiff model of information sharing to reduce community violence: natural experiment
Authors: Boyle Adrian A , Snelling Katrina , White Laura , Ariel Barak , Ashelford Lawrence
Published: November 2012

Background

Community violence is a substantial problem for the NHS. Information sharing of emergency department data with community safety partnerships (CSP) has been associated with substantial reductions in assault attendances in emergency departments supported by academic institutions. We sought to validate these findings in a setting not supported by a public health or academic structure.

Methods

We instituted anonymous data sharing with the police to reduce community violence, and increased involvement with the local CSP. We measured the effectiveness of this approach with routinely collected data at the emergency department and the police. We used police data from 2009, and emergency department data from 2000.

Results

Initially, the number of assault patients requiring emergency department treatment rose after we initiated data sharing. After improving the data flows, the number of assault patients fell back to the predata-sharing level. There was no change in the number of hospital admissions during the study period. There were decreases in the numbers of violent crimes against the person, with and without injury, recorded by the police.

Conclusions

We have successfully implemented data sharing in our institution without the support of an academic institution. This has been associated with reductions in violent crime, but it is not clear whether this association is causal.
Patients’ and carers’ experiences of gaining access to acute stroke care: a qualitative study
Authors: Harrison Madeleine , Ryan Tony , Gardiner Clare , Jones Amanda
Published: November 2012

Background

Rapid access to acute stroke care is essential to improve stroke patient outcomes. Policy recommendations for the emergency management of stroke have resulted in significant changes to stroke services, including the introduction of hyper-acute care.

Objective

To explore patients’ and carers’ experiences of gaining access to acute stroke care and identify the factors that enabled or prevented stroke from being treated as a medical emergency.

Methods

Qualitative semi-structured interviews were conducted with 59 stroke survivors and carers who had received care at seven UK centres. The interviews were recorded and transcribed verbatim and thematic analysis was undertaken.

Results

Themes emerging showed that participants recognised signs and symptoms, they were satisfied with access to emergency medical services (EMS), and they experienced setbacks in the emergency department and delays caused by the lack of availability of specialist services outside normal working hours. Awareness of the importance of time to treatment was generally attributed to the UK stroke awareness campaign, although some felt the message was not sufficiently comprehensive. This awareness led to increased frustration when participants perceived a lack of urgency in the provision of assessment and medical care.

Conclusions

The stroke awareness social marketing campaign has contributed to public knowledge and was perceived to assist in reducing prehospital delay. It has also resulted in an enhanced knowledge of the significance of rapid treatment on admission to hospital and raised public expectation of EMS and stroke services to act fast. More research is required to assist organisational change to reduce in-hospital delay.
CT perfusion-guided patient selection for endovascular recanalization in acute ischemic stroke: a multicenter study
Authors: Turk Aquilla S , Magarick Jordan Asher , Frei Don , Fargen Kyle Michael , Chaudry Imran , Holmstedt Christine A , Nicholas Joyce , Mocco J , Turner Raymond D , Huddle Daniel , Loy David , Bellon Richard , Dooley Gwendolyn , Adams Robert , Whaley Michelle , Fanale Chris , Jauch Edward
Published: November 2012

Background

The treatment of acute ischemic stroke is traditionally centered on time criteria, although recent evidence suggests that physiologic neuroimaging may be useful. In a multicenter study we evaluated the use of CT perfusion, regardless of time from symptom onset, in patients selected for intra-arterial treatment of ischemic stroke.

Methods

Three medical centers retrospectively assessed stroke patients with a National Institute of Health Stroke Scale of ≥8, regardless of time from symptom onset. CT perfusion maps were qualitatively assessed. Patients with defined salvageable penumbra underwent intra-arterial revascularization of their occlusion. Functional outcome using the modified Rankin Score (mRS) was recorded.

Results

Two hundred and forty-seven patients were selected to undergo intra-arterial treatment based on CT perfusion imaging. The median time from symptom onset to procedure was 6 h. Patients were divided into two groups for analysis: ≤8 h and >8 h from symptom onset to endovascular procedure. We found no difference in functional outcome between the two groups (42.8% and 41.9% achieved 90-day mRS ≤ 2, respectively (p=1.0), and 54.9% vs 55.4% (p=1.0) achieved 90-day mRS ≤ 3, respectively). Overall, 48 patients (19.4%) had hemorrhages, of which 20 (8.0%) were symptomatic, with no difference between the groups (p=1.0).

Conclusions

In a multicenter study, we demonstrated similar rates of good functional outcome and intracranial hemorrhage in patients with ischemic stroke when endovascular treatment was performed based on CT perfusion selection rather than time-guided selection. Our findings suggest that physiologic imaging-guided patient selection rather than time for endovascular reperfusion in ischemic stroke may be effective and safe.
Influence of infiltration on the periodic re-activation of slow movements in an overconsolidated clay slope
Authors: Tommasi Paolo , Boldini Daniela , Caldarini Giada , Coli Niccolò
Published: November 2012

In Orvieto (central Italy), overconsolidated clay slopes are affected by intermittent slow movements at the top of the clay formation and within the landslide debris cover. Monthly data from inclinometers, Casagrande piezometers, and rainfall gauges show that velocity, pore pressure, and rainfall are closely related. A relationship is suggested to predict slope re-activation using rainfall history alone, once a pore pressure threshold has been reached and response of pore pressures to rainfall is understood. Pore pressures have been continuously monitored through vibrating wire cells. The threshold for shallow movements, critical for infrastructures and buildings, was identified by comparing displacement histories of a shallow movement, representative of many other ones recognized over the slope, and pore pressure, both measured at the centre of the sliding mass. The impact of infiltrated rainfall on groundwater flow was investigated through transient seepage analyses. Seepage analyses performed using hydraulic properties from laboratory and in situ tests do not fully depict the observed pore pressures because field data miss some structural characters and lithologic variations. The hydraulic properties of the shallower model layers were refined, based on field observations and interpretation of monitoring data, to have a good match between computed and measured pore pressures. Once the model is tested at different locations along a slope, it could be used to predict movement re-activation using only rainfall data.
Preparation of graphite by thermal annealing of polyacrylamide precursor for adsorption of Cs(I) and Co(II) ions from aqueous solutions
Authors: Hassan H.S. , Elmaghraby Elsayed K.
Published: November 2012

In the present work, graphite nanostructures are prepared by thermolysis of a prepared polyacrylamide gel. The gel was prepared by radical chain polymerization and the synthesis of the nanostructures was done by step annealing at different temperatures. The structural of the prepared materials was studied by X-ray diffraction (XRD). The presence of carboxylic and phenolic functional groups on the graphite surface was confirmed by FT-IR analysis. Batch adsorption experiments were conducted to study the effect of equilibration time, initial metal cation concentration, and solution pH for the removal of Cs(I) and Co(II) from aqueous solutions. Kinetic data of Cs(I) adsorption was found to be well fitted with a pseudo-first-order kinetic model. The obtained isotherm data were correlated with the Langumir and Freundlich isotherm models. The effect of temperature on the equilibrium distribution values was utilized to evaluate the change in the standard thermodynamic quantities of enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°).
2-Hydroxyethylammonium acetate as a reusable and cost-effective ionic liquid for the efficient synthesis of bis(pyrazolyl)methanes and 2-pyrazolyl-1-nitroalkanes
Authors: Sobhani Sara , Nasseri Razieh , Honarmand Moones
Published: November 2012

A new and convenient method for the synthesis of bis(pyrazolyl)methanes by one-pot tandem Knoevenagel–Michael reaction of 3-methyl-1-phenyl-5-pyrazolone with aryl, heteroaryl, or alkyl aldehydes in the presence of 2-hydroxyethylammonium acetate (2-HEAA) as a task-specific ionic liquid is described. This method was also successfully applied for the synthesis of 2-pyrazolyl-1-nitroalkanes by Michael addition of 3-methyl-1-phenyl-5-pyrazolone with β-nitrostyrenes in short reaction times. The present protocol offers several advantages such as using a reusable and cost-effective ionic liquid, an environmentally benign reaction media, being amenable to scale-up and good to high yields of the products.
Separation of bitumen from oil sands using a switchable hydrophilicity solvent
Authors: Holland Amy , Wechsler Dominik , Patel Anjali , Molloy Brian M. , Boyd Alaina R. , Jessop Philip G.
Published: November 2012

Separation of bitumen from oil sands is far more efficient with an organic solvent than with the conventional hot water (Clark) process, but the removal of the organic solvent from the bitumen requires distillation. Distillation is problematic because of the energy cost and the need for a volatile solvent (which is therefore likely to be flammable and smog-forming). A switchable hydrophilicity solvent (SHS) is a solvent that is water-miscible in the presence of an atmosphere of CO2 but separates from water when CO2 is absent. Extraction of bitumen from low-grade high-fines oil sands using a SHS (CyNMe2) is efficient, removing 94%–97% of the bitumen. The resulting solids (sand and clay) are dry, free-flowing, and contaminated with only 0.4 wt % of bitumen and as little as 102 ppm of the solvent. No distillation step was required to recover the solvent from the bitumen. Instead, carbonated water extraction removed the solvent from the oil. Losses of the CyNMe2 solvent were, for the best method, 0.06 grams of solvent per gram of bitumen recovered. The method recovers more oil than the Clark process, produces cleaner solids, works with low-grade high-fines oil sands, and requires neither distillation nor a volatile solvent.
Polyethersulfone polymers and oligomers — Morphology and crystallization
Authors: Benhalima Abdelkader , Hudon François , Koulibaly Finda , Tessier Christian , Brisson Josée
Published: November 2012

Crystal forms of polyethersulfones (PES) were investigated by using a model compound and a low molecular weight oligomer. These are amorphous as-synthesized, and can undergo solvent-induced crystallization under the appropriate conditions. The model compound, 4,4′-bis(p-methoxyphenoxy)diphenyl sulfone, yielded monocrystals, and its structure was solved using X-ray diffraction. Conformational disorder is present, two conformers cohabiting in 55:45 proportions. This model compound, combined to previous structural studies published in the literature, served as a basis for conformational studies of polyethersulfone. Low molecular weight polymers submitted to solvent-induced crystallization resulted in a PES crystal form different from that previously published in the literature, as shown by powder X-ray diffraction.
Formal transfer potentials of strontium and uranyl ions at water|1,2-dichloroethane interfaces
Authors: Stockmann Tom J. , Montgomery Anne-Marie , Ding Zhifeng
Published: November 2012

The extraction of dioxouranium (UO22+), or uranyl, and strontium (Sr2+) ions from spent nuclear fuel (SNF), often through a biphasic (aqueous / organic solvent) ligand assisted process, is critical for the implementation of a closed-loop nuclear fuel cycle whereby SNF is diverted from permanent geological disposal and the life of the nuclear industry is extended. Deeper understanding of the biphasic extraction process can be achieved through facile electrochemical experiments at a liquid|liquid interface. Of primary importance to developing a quantitative analysis of the ligand assisted or facilitated ion transfer (FIT) (i.e., transfer through interfacial complexation) case is to first quantify the free or simple metal IT; that is the amount of applied potential required to “push” ions across the water|organic interface. This value is, in fact, a constant referred to as the formal transfer potential ([Formula: see text]), which is unique to each metal ion in the biphasic system. Because of their hydrophilicity they often limit the polarizable potential window. Values for [Formula: see text], for the most part, have only been estimated. With a microinterface housed at the tip of a 25 µm capillary it is possible to reduce the Faradaic current to observe their transfer. Herein is described the quantification of [Formula: see text] and [Formula: see text] or the formal transfer potentials for dioxouranium and strontium ions, respectively.
A solid-state NMR investigation of the colossal expansion material, Ag3Co(CN)6
Authors: Feland Brett C. , Bernard Guy M. , Wasylishen Roderick E.
Published: November 2012

Presented here is a solid-state NMR investigation of the so-called “colossal expansion” material, Ag3Co(CN)6, a compound that exhibits some of the largest positive and negative thermal expansion properties reported. This study explores the 13C, 15N, and 59Co NMR properties of this material at room temperature and at variable temperatures with the goal of probing the effects of this colossal expansion behaviour on these properties. We found that the flexible nature of the crystal framework leads to a distribution of electric field gradients, and that, oddly enough, no strong correlation is observed between the NMR parameters of Ag3Co(CN)6 and its colossal expansion nature. The 59Co isotropic chemical shift increased and the 59Co nuclear quadrupolar coupling constant decreased with increasing temperature, but neither of these relationships were extraordinary when compared to other octahedral Co(III) complexes. The link between the colossal expansion and the NMR properties of Ag3Co(CN)6 may be the distribution of lattice parameters and hence unusually broad features in the 59Co NMR spectra. The high order of symmetry at the cobalt site resulted in a small quadrupolar coupling constant less than 1 MHz in magnitude. We also observed a |1J(107/109Ag,15N)| value of 96 Hz, the largest 107/109Ag–15N coupling constant reported to date.
Complexations of the hydrophilic and hydrophobic moieties of benzethonium chloride by cucurbit[7]uril in aqueous solution
Authors: MacGillivray Brendan C. , Macartney Donal H.
Published: November 2012

The sequential complexations of the hydrophilic and hydrophobic end groups of benzethonium chloride by cucurbit[7]uril (CB[7]) in aqueous solution have been investigated using 1H NMR spectroscopy and electrospray ionization mass spectrometry. The initial binding is to the benzyldimethylammonium group, with a stability constant of (8.7 ± 3.1) × 107 (mol/L)–1. This binding constant and the complexation-induced upfield shifts of the benzyl guest protons are similar to those values observed with other cationic guests containing benzyl moieties. This equilibrium is followed by the binding of a second equivalent of the host to the hydrophobic 2-(2,4,4-trimethylpentyl) group, with a stability constant of (4.0 ± 1.9) × 103 (mol/L)–1. The relatively strong binding of this uncharged hydrophobic end of the guest molecule is consistent with the inclusion of eight heavy (nonhydrogen) atoms within the inner cavity of CB[7], with its low polarizability. The packing coefficient for the 2-(2,4,4-trimethylpentyl) group with the inner cavity is calculated to be 61%, close to Rebek’s ideal value of 55%.
Photochemical conversion of AgCl nanocubes to hybrid AgCl–Ag nanoparticles with high activity and long-term stability towards photocatalytic degradation of organic dyes
Authors: Wang Jizhuang , An Changhua , Zhang Meiyu , Qin Chuan , Ming Xijuan , Zhang Qinhui
Published: November 2012

The performance of a photocatalytic reaction is mainly determined by the quality of the photocatalyst. For real applications, significantly enhancing the stability and activity of the photocatalysts still remains a challenge for materials scientists and chemists. In this paper, we have achieved a highly efficient plasmonic AgCl–Ag nanophotocatalyst via photochemical conversion of AgCl nanocubes. Compared with reported photocatalysts, the as-achieved nanophotocatalyst exhibits superior activity, long-term stability, and wide applicability in the decomposition of organic dye pollutants. For example, only 30 s is needed to bleach methyl orange molecules assisted by AgCl–Ag nanoparticles. Furthermore, the catalyst can be reused up to 50 times without significant loss of activity. A possible mechanism was discussed and the specified photocatalytic reactions verified that both O2•– and OH• radicals were the main active species in decomposing pollutants. The excellent performance of the present photocatalyst suggests promising applications in environmental remediation, clean energy creation, and solar cells.
Application of the high-speed self-reversal background corrector to the determination of cadmium by chemical vapor generation atomic absorption spectrometry
Authors: Waterlot Christophe , Pelfrêne Aurélie , Douay Francis
Published: November 2012

Concentrations of cadmium (Cd) in extracting solutions (neutral salts) from contaminated soils are often too low to be determined by conventional flame atomic absorption spectrometry. For this reason, determination of Cd requires sensitive analytical methods free from interference problems generated by samples. In this context, vapor generation atomic absorption spectrometry (HGAAS) was combined with a high-speed self-reversal background corrector. This new approach was successfully applied after optimization of the analytical parameters to obtain a maximal absorbance signal of the volatile Cd species. The optimum condition was achieved with a 3% (m/v) NaBH4 in 1.5% (m/v) NaOH reducing solution and a solution containing 0.3 mol/L HNO3. The detection limit was 1 ng mL–1 under the previous conditions and the relative standard deviation was up to 5% for 10 replicate analyses of Cd at 0.2 and 1 ng mL–1, reflecting a very highly sensitive and reproducible method. Moreover, the results showed that the proposed combination was an efficient method to overcome the interference problems caused by different coexisting cations, As, Al, Ca, Cu, Fe, Mg, Mn, Ni, Pb, Se and Zn, up to 10 µg mL–1. The method was validated with analyses of two standard reference materials and was used for Cd determination in 0.01 mol/L CaCl2 extracts from contaminated kitchen garden soils. The data were compared with those obtained by two other more conventional methods, electrothermal atomic absorption spectrometry (ETAAS) and flame atomic absorption spectrometry (FAAS). The analytical results obtained by the ETAAS and HGAAS were in a good agreement, suggesting the suitability of the method for Cd determination in 0.01 mol/L CaCl2 extracting solution.
(QUANTUMNESS IN THE CONTEXT OF) RESOURCE THEORIES
Authors: HORODECKI MICHAL , OPPENHEIM JONATHAN
Published: November 2012

We review the basic idea behind resource theories, where we quantify quantum resources by specifying a restricted class of operations. This divides the state space into various sets, including states which are free (because they can be created under the class of operations), and those which are a resource (because they cannot be). One can quantify the worth of the resource by the relative entropy distance to the set of free states, and under certain conditions, this is a unique measure which quantifies the rate of state to state transitions. The framework includes entanglement, asymmetry and purity theory. It also includes thermodynamics, which is a hybrid resource theory combining purity theory and asymmetry. Another hybrid resource theory which merges purity theory and entanglement can be used to study quantumness of correlations and discord, and we present quantumness in this more general framework of resource theories.
OPTIMAL RANDOM AGE REPLACEMENT FOR AVAILABILITY
Authors: ANGUS JOHN E. , YIN MENG-LAI , TRIVEDI KISHOR
Published: November 2012

An age replacement maintenance policy is considered here, in which a system is restored whenever it fails, or ages without failure up to a preventive maintenance epoch (whichever comes first). The duration of the restoration activity is random, and depends on whether it was precipitated by a failure or by a preventive maintenance action. The case where the preventive maintenance epoch is deterministic has been studied previously, and shown to be optimal in a certain sense. Here, we consider the case where the preventive maintenance epoch is randomized, which is more realistic for many systems. The system availability is the long run proportion of time that the system is operational (i.e., not undergoing repair or preventive maintenance). The optimal rate of preventive maintenance to maximize availability is considered, along with sufficient conditions for such an optimum to exist. The results obtained herein are useful to systems engineers in making critical design decisions.
COMMENTS REGARDING d-IDEALS OF CERTAIN f-RINGS
Authors: DUBE THEMBA , IGHEDO OGHENETEGA
Published: November 2012

Let A be a reduced commutative f-ring with identity and bounded inversion, and let A* be its subring of bounded elements. By first observing that A is the ring of fractions of A* relative to the subset of A* consisting of elements which are units in the bigger ring, we show that the frames Did (A) and Did (A*) of d-ideals of A and A*, respectively, are isomorphic, and that the isomorphism witnessing this is precisely the restriction of the extension map I ↦ Ie which takes a radical ideal of A* to the ideal it generates in A. Specializing to the ring [Formula: see text], we show that if L is an F-frame, then the saturation quotient of [Formula: see text] is isomorphic to βL. We also investigate projectability properties of [Formula: see text] and [Formula: see text], where the latter denotes the frame of z-ideals of [Formula: see text]. We show that [Formula: see text] is flatly projectable precisely when [Formula: see text] is a feebly Baer ring. Quite easily, [Formula: see text] is projectable if and only if L is basically disconnected. Less obvious is that [Formula: see text] is projectable if and only if L is cozero-complemented.
BUCKLING OF NANO-RINGS/ARCHES BASED ON NONLOCAL ELASTICITY
Authors: WANG C. M. , XIANG Y. , YANG J. , KITIPORNCHAI S.
Published: November 2012

This paper is concerned with the bifurcation buckling of nano-rings and nano-arches where the allowance for small scale effect is catered for by using Eringen's nonlocal theory of elasticity. Exact buckling solutions for nano-rings and nano-arches under uniform radial pressure are derived and the influence of small scale effect on the buckling pressures and mode shapes is investigated. The new results presented will be useful to engineers who are designing nano-rings and nano-arches to be used in MEMS and NEMS devices.
ANALYSIS OF DYNAMIC AND ACOUSTIC RADIATION CHARACTERS FOR A FLAT PLATE UNDER THERMAL ENVIRONMENTS
Authors: GENG QIAN , LI YUEMING
Published: November 2012

A study on vibration and acoustic radiation characters of an isotropic rectangular thin plate under thermal environments is presented in this paper. It is assumed that thermal loads caused by thermal environments just change the structure stress state. Thermal stresses induced by uniform temperature rise of the plate are determined with the thermo-elastic theory. Then the stress state is used in the following dynamic analysis as a pre-stressed factor. It is observed that thermal loads influence the natural frequencies evidently, especially the fundamental natural frequency. The order of mode shapes stays the same. Dynamic response peaks float to lower frequency range with the increment of structure temperature. Acoustic radiation efficiency of the plate subjected to thermal loads decreases in the mid-frequency band. For validation, numerical simulations are also carried out. It can be found that the combined approach of finite element method (FEM) and boundary element method (BEM) is more appropriate for radiation problems.
EARTHQUAKE-INDUCED TOPPLING FAILURE MECHANISM AND ITS EVALUATION METHOD OF SLOPE IN DISCONTINUOUS ROCK MASS
Authors: CHE AILAN , GE XIURUN
Published: November 2012

The seismic behavior of rock slopes accompanied with discontinuity is heavily governed by the geometrical distribution and mechanical properties of discontinuity. Especially, high and steep rock slopes, which are dominated by sub-vertical discontinuity, are likely to collapse due to toppling failure and it causes serious damage to structures surrounding the slopes. Ten thousands of landslides, collapses and other geological disasters occurred in the Wenchuan Ms 8.0 great earthquake on May 12, 2008 in Sichuan province of central China. The field survey during the disaster investigations indicated that it shows the tensile failure close to the top of slop and the shear failure below it. However, it is difficult to assess quantitatively toppling failure potential. In order to clarify mechanism of toppling failure in rock slopes and evaluation on seismic stability, 2D joint elements around each rock column is proposed to simulate the discontinuity of rock slope, which is different from Goodman joint and composed with normal spring Knand shear spring Kswithout volume. By a nonlinear numerical FEM analysis, the dynamic response of the rock slopes could demonstrate the landslide mechanism. Coupled with the effect of amplification on the toppling, the seismic horizontal acceleration at the top of slopes is often large, and then coursed inertia force would far exceed the tensile strength of rock mass. Eventually, the opening and sliding of joint elements occurs on the slope are identified based on the nonlinear characteristics of the joint elements. The result shows that a toppling failure could have occurred on the slope and the sliding plane also could be observed, which shows agreement with the existing investigation flexural toppling failure during the Wenchuan great earthquake.
LAND-USE AND GREENHOUSE GAS IMPLICATIONS OF BIOFUELS: ROLE OF TECHNOLOGY AND POLICY
Authors: CHEN XIAOGUANG , HUANG HAIXIAO , KHANNA MADHU
Published: November 2012

This paper examines the changes in land use in the U.S. likely to be induced by biofuel and climate policies and the implications of these policies for greenhouse gas (GHG) emissions over the 2007–2022 period. The policies considered here include a modified Renewable Fuel Standard (RFS) by itself as well as combined with a cellulosic biofuel tax credit or a carbon price policy. We use a dynamic, spatial, multi-market equilibrium model, Biofuel and Environmental Policy Analysis Model (BEPAM), to endogenously determine the effects of these policies on cropland allocation, food and fuel prices, and the mix of first- and second-generation biofuels. We find that the RFS could be met by diverting 6% of cropland for biofuel production and would result in corn prices increasing by 16% in 2002 relative to the business-as-usual baseline. The reduction in GHG emissions in the U.S. due to the RFS is about 2%; these domestic GHG savings can be severely eroded by emissions due to indirect land-use changes and the increase in gasoline consumption in the rest of the world. Supplementing the RFS with a carbon price policy or a cellulosic biofuel tax credit induces a switch away from corn ethanol to cellulosic biofuels and achieves the mandated level of biofuel production with a smaller adverse impact on crop prices. These supplementary policies enhance the GHG savings achieved by the RFS alone, although through different mechanisms; greater production of cellulosic biofuels with the tax credit but larger reduction in fossil fuel consumption with a carbon tax.
LAND-USE CHANGE AND GREENHOUSE GAS EMISSIONS IN THE FAPRI-CARD MODEL SYSTEM: ADDRESSING BIAS AND UNCERTAINTY
Authors: ELOBEID AMANI E. , CARRIQUIRY MIGUEL A. , FABIOSA JACINTO F.
Published: November 2012

Even with a normalized and standardized biofuel shock, the wide range of land-use change estimates and their associated greenhouse gas (GHG) emissions have raised concern on the adequacy of existing agricultural models in this new area of analysis. In particular, reducing bias and improving precision of impact estimates are of primary concern to policy makers. This paper provides a detailed overview of the FAPRI-CARD agricultural modeling system, with particular emphasis on the modifications recently introduced to reduce bias in the results. We illustrate the impact of these new model features using the example of the new yield specification that now includes updated trend parameter, intensification and extensification effects, and a spatially disaggregated Brazil specification. The paper also provides a taxonomy of the many types of uncertainty surrounding any analysis, including parameter-coefficient uncertainty and exogenous variable uncertainty, identifying where specific types of uncertainty originate, and how they interact. Finally, FAPRI-CARD's long experience in using stochastic analysis is presented as a viable approach in addressing uncertainty in the analysis of changes in the agricultural sector, associated land-use change, and impacts on GHG emissions.
MODELING THE LAND-USE AND GREENHOUSE-GAS IMPLICATIONS OF BIOFUELS
Authors: KHANNA MADHU , ZILBERMAN DAVID
Published: November 2012

The emergence of biofuels as an agricultural commodity has integrated the agricultural, energy and livestock sectors and expanded the scope of models being used to analyze the effects of energy policies. It has increased the importance of incorporating spatial heterogeneity in land availability and productivity and information about the biophysical and economic determinants of land use change at multiple spatial scales. Since biofuels affect food and fuel prices, they have expanded the boundaries of economic models to consider not only their direct but also their indirect effects on land use and greenhouse gas emissions. This paper describes the demand-side and supply-side determinants of these direct and indirect changes in land use and greenhouse gas emissions with biofuels. We discuss the major modeling approaches used to analyze these effects, their strengths, limitations and key findings and directions for future research.
Variability of Pennsylvanian–Permian Carbonate Associations and implications for NW Pangea Palaeogeography, east-central British Columbia, Canada
Authors: Zubin-Stathopoulos K. D. , Beauchamp B. , Davydov V. I. , Henderson C. M.
Published: November 2012

Pennsylvanian–Early Permian carbonate sedimentation in east-central British Columbia records a complex history of changing environments influenced by evolving palaeogeography and climate. Newly recognized tectonically controlled features affected the distribution and variability of carbonate associations, providing new interpretations for this portion of the NW coast of Pangea. Both a heterozoan (cool-water) and photozoan (warm-water) association were identified on either side of a palaeogeographical high. Cool-water carbonates were located outboard or to the west of this high, an area influenced by upwelling waters. Inboard of this high, a warm, protected sea developed at about 20°N palaeolatitude during the Asselian and Sakmarian. This configuration and palaeolatitude is similar to that of Baja California, Mexico and the Sea of Cortéz, providing a good modern analogue for these deposits where warm-water carbonates grow at latitudes otherwise dominated by cool-water deposits. The warm sea provided a place for a photozoan association to develop during the Early Permian when the low-latitude NW coast of Pangea was dominated by cool-water carbonates.