With the advent of high-flux density permanent magnets based on rare earth elements such as neodymium (Nd) in the 1980s, permanent magnet-based electric machines had a clear performance and cost ...advantage over induction machines when weight and size were factors such as in hybrid electric vehicles and wind turbines. However, the advantages of the permanent magnet-based electric machines may be overshadowed by supply constraints and high prices of their key constituents, rare earth elements, which have seen nearly a 10-fold increase in price in the last 5 years and the imposition of export limits by the major producing country, China, since 2010. We outline the challenges, prospects, and pitfalls for several potential alloys that could replace Nd-based permanent magnets with more abundant and less strategically important elements.
Aliment Pharmacol Ther 2011; 34: 263–273
Summary
Background Cyclic vomiting syndrome is a disorder characterised by recurrent episodes of severe nausea and vomiting separated by symptom‐free ...periods.
Aims To review the history, epidemiology, clinical aspects, pathophysiology, diagnosis and treatments of adult cyclic vomiting syndrome as well as to identify areas for further clinical research and the unanswered questions in this field.
Methods We conducted a PubMed search using such keywords as cyclic vomiting syndrome; nausea; vomiting; pathophysiology; diagnosis; treatment; trigger factors; gastric emptying test; autonomic nerve function test; gastrointestinal hormones; outcome and natural history and combined this information with the knowledge and extensive clinical research and publications from the authors.
Results Available data show that in adult cyclic vomiting syndrome, severe epigastric and sometimes diffuse abdominal pain accompanies most cycles of nausea and vomiting interspersed with periods of symptomatic remission. Psychological disorders, specifically anxiety and depression are common, and gastric emptying is actually rapid in approximately 60% of patients and normal in the remainder. There is an impressive and sustained response to high‐dose tricyclic antidepressants. In up to 15% who are regarded as poor responders to tricyclic antidepressants, a predictable profile can be identified related to co‐existing psychological disorders, marijuana use, poorly controlled migraine headache or chronic narcotic use.
Conclusions Cyclic vomiting syndrome in adults is an entity that is being increasingly recognised, but the need to educate Internists, Gastroenterologists and Emergency Department staff remains an ongoing challenge.
A rare-earth supply crisis has stimulated an intensive search for alternative permanent magnets. Alnico materials, alloys containing Al, Ni, Co and Fe, are functional nanostructured alloys, which ...show great potential for replacing the best commercial Nd-based rare-earth alloys for applications above 200°C. However, their coercivity is ∼2–3× below theoretical limits. The coercivity of alnico depends on the nanostructure developed during spinodal decomposition. In this work, atom probe tomography, combined with advanced electron microcopy, indicate that the microstructure of alnico is sensitive to the introduction of alloying elements such as Ti and Cu, as well as the crystallographic orientation of the parent phase with respect to the direction of the imposed magnetic field during spinodal decomposition. The alnico coercivity mechanism involves interplay of size, chemistry and possibly stress at interfaces. Control of these parameters should allow reduction of the spatial dimension of the FeCo-rich precipitates and the interaction between them, which should in term increase the coercivity of alnico alloys.
Magnetic properties of Ce and Co co-doped (Nd1-xCex)2Fe14-yCoyB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce ...concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply). The high temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd2Fe14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.
Transmission electron microscopy (TEM) micrographs of the free side (a), the wheel side (b) of (Nd0.8Ce0.2)2Fe14B melt spun ribbon. (c) Maximum energy product, (BH)max, as functions of temperature for melt spun ribbons of Nd2Fe14B, (Nd0.8Ce0.2)2Fe14B and (Nd0.8Ce0.2)2Fe14Co2B. Display omitted
Background & Aims
Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, ...possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta‐analysis of case–control studies that compared immune cell counts in colonic biopsies of IBS patients and controls.
Methods
PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I2 statistics where I2 ≤ 50% and I2 > 50% indicated fixed and random effect models, respectively.
Key Results
Twenty‐two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 95% CI: 0.06‐0.71; P = .02) and descending colon (SMD: 1.69 95% CI: 0.65‐2.73; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS‐C) and diarrhea predominant IBS (IBS‐D). CD3+ T cells were increased in the rectosigmoid (SMD: 0.53 95% CI: 0.21‐0.85; P = .001) and the descending colon of the IBS patients (SMD: 0.79, 95% CI 0.28‐1.30; P = .002). This was possibly in relation to higher CD4+ T cells in IBS (SMD: 0.33 95% CI: 0.01‐0.65; P = .04) as there were no differences in CD8+ T cells.
Conclusions & Inferences
Mast cells and CD3+ T cells are increased in colonic biopsies of patients with IBS vs non‐inflamed controls. These changes are segmental and sometimes IBS‐subtype dependent. The diagnostic value of the quantification of colonic mucosal cells in IBS requires further investigation.
Studies have indicated changes in the intestinal immune cell counts of IBS patients; however, these findings are not consistent. The current study shows that the number of colonic mast cells, CD3+ T cells and CD4+ T cells are increased in IBS. These changes are colonic segmental and sometimes IBS‐subtype dependent. Figure shows density/number of mast cells in colorectal biopsies of patients with IBS vs healthy controls. (A) Ascending colon, (B) Descending colon, (C) Rectosigmoid.
Summary
Background Gastric emptying scintigraphy (GES) using a radio‐labelled meal is used to measure gastric emptying. A nondigestible capsule, SmartPill, records luminal pH, temperature, and ...pressure during gastrointestinal transit providing a measure of gastric emptying time (GET).
Aims To compare gastric emptying time and GES by assessing their correlation, and to compare GET and GES for discriminating healthy subjects from gastroparetics.
Methods Eighty‐seven healthy subjects and 61 gastroparetics enrolled with simultaneous SmartPill and GES. Fasted subjects were ingested capsule and 99mTc‐SC radio‐labelled meal. Images were obtained every 30 min for 6 h. Gastric emptying time and percentage of meal remaining at 2/4 h were determined for each subject. The sensitivity/specificity and receiver operating characteristic analysis of each measure were determined for each subject.
Results Correlation between GET and GES‐4 h was 0.73 and GES‐2 h was 0.63. The diagnostic accuracy from the receiver operating characteristic curve between gastroparetics and healthy subjects was GET = 0.83, GES‐4 h = 0.82 and GES‐2 h = 0.79. The 300‐min cut‐off time for GET gives sensitivity of 0.65 and specificity of 0.87 for diagnosis of gastroparesis. The corresponding sensitivity/specificity for 2 and 4 h standard GES measures were 0.34/0.93 and 0.44/0.93, respectively.
Conclusion SmartPill GET correlates with GES and discriminates between healthy and gastroparetic subjects offering a nonradioactive, standardized, ambulatory alternative to scintigraphy.
The aims were to investigate the effects of gastric electrical stimulation (GES) on autonomic function, gastric distention and tone, and central control mechanisms in gastroparetic patients. Ten ...gastroparetic patients refractory to standard medical therapy participated in this study and data were collected at baseline, within two weeks before surgery for implantation of GES system, and at follow‐up sessions between 6 and 12 weeks after GES therapy was initiated. In each session, electrocardiogram, electrogastrogram (EGG) and gastric barostat measurements were conducted before and after a caloric liquid meal. Positron Emission Tomography (PET) brain scans were performed on a separate day. During GES therapy there was a significant increase in the discomfort threshold for mean pressure from 21 mmHg at baseline to 25 mmHg at follow‐up, and for mean volume from 561 mL to 713 mL. A significant increase in the postprandial EGG power (amplitude) was observed between baseline and follow up. The sympathovagal balance was significantly decreased after GES therapy, indicating a significant increase in vagal activity. The cumulative PET data showed an increase in quantitative radioactive counts relative to the standardized data base in both the thalamic and caudate nuclei after chronic GES therapy. We conclude that our data suggest that the symptomatic improvement achieved by GES in gastroparesis is best explained by activation of vagal afferent pathways to influence CNS control mechanisms for nausea and vomiting accompanied by enhanced vagal efferent autonomic function and decreased gastric sensitivity to volume distention which enhances postprandial gastric accommodation.
The in-operando stabilities of AlFe2B2-based (aka, 1-2-2) compounds were investigated by mimicking two separate operating conditions (immersion in a heat transfer fluid and magnetic field cycling) of ...an active magnetic regenerator (AMR) refrigerator. Parent AlFe2B2 and Ga-containing samples of nominal composition Al1.2-xGaxFe2B2 (x = 0, 0.05 and 0.1) were prepared by casting and subsequent annealing. The chemical stability of pulverized (Al,Ga)Fe2B2-based compounds subjected to water immersion at room temperature for up to 960 h was evaluated. In a separate test, the mechanical stability of dry (Al,Ga)Fe2B2 cast-disk-shaped samples was studied utilizing a device constructed to mimic the AMR field cycling process. The materials’ responses as a function of water-immersion time or of magnetic field cycles were assessed by probing the crystal structure, the microstructure, the magnetic characters and the magnetocaloric response as quantified by the magnetic entropy change ΔSmag. The water-immersed pulverized samples exhibit exponential-decay-like degradations in magnetization and in ΔSmag. The Ga-containing compound exhibits significantly smaller reductions in magnetization and in ΔSmag after 960 h of water immersion relative to those of the Ga-free composition. In the separate magnetic-field-cycling test conducted under a dry condition, the structural and the magnetocaloric responses of both the Ga-free and Ga-containing disks remain similar after ∼5 × 105 cycles in and out of a 0.5 T magnetic field. The decrease in the magnetocaloric response during water immersion is attributed to the formation of oxide and/or hydroxide phases that reduced the AlFe2B2 phase fraction. The stable structure and the constant magnetocaloric response observed after magnetic field cycling are attributed to the extremely small unit cell volume change of AlFe2B2 through its magnetic phase transition. Overall, these results demonstrate that the AlFe2B2-based compounds exhibit good chemical stability upon water immersion that is improved by small Ga additions, and robust mechanical integrity upon dry magnetic field cycling, suggesting that AlFe2B2-based compounds are promising as robust AMR magnetic refrigeration working materials.
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•The first report assessing the engineering stabilities of AlFe2B2-based compounds for magnetic refrigeration.•Novel testing apparatus was designed and built to mimic the active magnetic regenerator (AMR)-type operating conditions.•Small alloying additions of gallium enable improvement of the AlFe2B2 stabilities.•In terms of in-operando stabilities, AlFe2B2-based compounds outperform other existing MCE materials families.•Results provide technological insights into the magnetocaloric potential of AlFe2B2-based compounds.
The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of ...the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.
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