Effect of specific surface area on syngas production performance of pure ceria in high-temperature thermochemical redox cycling coupled to methane partial oxidation

Specific surface area is a key parameter determining the rates of thermochemical redox reactions in metal oxides. We have experimentally investigated the effect of specific surface area on syngas production of pure ceria powders under two experiments such as a heating experiment without syngas production and an isothermal thermochemical redox cycling experiment using carbon dioxide splitting and methane partial oxidation. The specific surface area of ceria powders decreased relatively slowly during 50 hours of ceria powder heating without syngas production due to a combination of oriented attachment and grain-boundary diffusion. When cycled thermochemically, the specific surface area of ceria powders rapidly decreased only in the initial 10 minutes of reduction in the 1st cycle due to evaporation and condensation. A significant decrease of specific surface area during the initial stage of thermochemical ceria powder cycling is unavoidable even if temperatures as low as T = 1173 K are used in the reduction reaction coupled to methane partial oxidation.

Specific surface area is a key parameter determining the rates of thermochemical redox reactions in metal oxides.     

Adolescent Exposure to WIN 55212-2 Render the Nigrostriatal Dopaminergic Pathway Activated During Adulthood

BackgroundDuring adolescence, neuronal circuits exhibit plasticity in response to physiological changes and to adapt to environmental events. Nigrostriatal dopaminergic pathways are in constant flux during development. Evidence suggests a relationship between early use of cannabinoids and psychiatric disorders characterized by altered dopaminergic systems, such as schizophrenia and addiction. However, the impact of adolescent exposure to cannabinoids on nigrostriatal dopaminergic pathways in adulthood remains unclear. The aim of this research was to determine the effects of repeated activation of cannabinoid receptors during adolescence on dopaminergic activity of nigrostriatal pathways and the mechanisms underlying this impact during adulthood.MethodsMale Sprague-Dawley rats were treated with 1.2 mg/kg WIN 55212-2 daily from postnatal day 40 to 65. Then no-net flux microdialysis of dopamine in the dorsolateral striatum, electrophysiological recording of dopaminergic neuronal activity, and microdialysis measures of gamma-aminobutyric acid (GABA) and glutamate in substantia nigra par compacta were carried out during adulthood (postnatal days 72–78).ResultsRepeated activation of cannabinoid receptors during adolescence increased the release of dopamine in dorsolateral striatum accompanied by increased population activity of dopamine neurons and decreased extracellular GABA levels in substantia nigra par compacta in adulthood. Furthermore, perfusion of bicuculline, a GABAa antagonist, into the ventral pallidum reversed the increased dopamine neuron population activity in substantia nigra par compacta induced by adolescent cannabinoid exposure.ConclusionsThese results suggest that adolescent exposure to cannabinoid agonists produces disinhibition of nigrostriatal dopamine transmission during adulthood mediated by decreased GABAergic input from the ventral pallidum.     

Mitigation of Cd toxicity by Mn in young plants of cacao,evaluated by the proteomic profiles of leaves and roots

Cd is a non-essential metal and highly toxic to plants, animals and humans, even at very low concentrations. Cd has been found in cocoa beans and in their products, as in the case of chocolate. Mn plays an important role in photosynthetic and can interact with Cd and attenuate its toxic effects on plants. The objective of this work was to evaluate the mechanisms of Mn response in the mitigation of Cd toxicity in young plants of the CCN 51 cacao genotype submitted to 0.8?mmol?Cd kg^?1, 1.6?mmol Mn kg^?1 or the combination of 0.4?mmol?Cd kg^?1?+?0.8?mmol Mn kg^?1 soil, together with the control treatment (without addition of Cd and Mn in soil), by means of analysis of changes in the profile of exclusive proteins (EP) and differentially accumulated proteins (DAP). Leaf and root proteins were extracted and quantified from the different treatments, followed by proteomic analysis. About eight DAP and 38 EP were identified in leaves, whereas in roots 43 DAP and 21 EP were identified. Some important proteins induced in the presence of Cd and repressed in the presence of Cd?+?Mn or vice versa, were ATPases, isoflavone reductase, proteasome and chaperonin. It was concluded that proteins involved in oxidoreduction and defense and stress response processes, in addition to other processes, were induced in the presence of Cd and repressed in the presence of Cd?+?Mn. This demonstrated that Mn was able to mitigate the toxic effects of Cd on young plants of the CCN 51 cocoa genotype.

     

Does Cyclic Stress Play a Role in Highly Crosslinked Polyethylene Oxidation?

Background

Minimizing the impact of oxidation on ultrahigh-molecular-weight polyethylene components is important for preserving their mechanical integrity while in vivo. Among the strategies to reduce oxidation in modern first-generation highly crosslinked polyethylenes (HXLPEs), postirradiation remelting was considered to afford the greatest stability. However, recent studies have documented measurable oxidation in remelted HXLPE retrievals. Biologic prooxidants and physiologic loading have been proposed as potential mechanisms.

Questions/purposes

In our pilot study, we asked: (1) Does cyclic stress induced by wear or (2) by cyclic compression loading increase oxidation and crystallinity of remelted HXLPE? (3) Does oxidative aging reduce the wear resistance of remelted HXLPE?

Methods

Remelted and annealed HXLPE prisms (n = 1 per test condition) were tested in a wear simulator for 500,000 cycles. After wear testing, some samples were subjected to accelerated aging and then wear-tested again. Wear track volumes were characterized by confocal microscopy. Thin films (200-μm thick) were microtomed from wear prisms and then used for Fourier transform infrared spectroscopy oxidation and crystallinity assessments. Remelted HXLPE compression cylinders (n = 1 per test condition) were subjected to fatigue experiments and similar oxidation characterization.

Results

Remelted HXLPE qualitatively showed low oxidation indices (≤ 1) when subjected either to cyclic loading or aging alone. However, oxidation levels almost doubled in near-surface regions when remelted HXLPE samples underwent consecutive cyclic loading, artificial aging, and cyclic loading steps. The type of loading (wear versus compression fatigue) appeared to not affect the oxidation behavior in the studied conditions. Annealed HXLPE showed higher oxidation (oxidation index > 3) than remelted HXLPE and delamination wear. No delamination wear was observed in remelted HXLPE in agreement with its comparatively low oxidation levels (oxidation index < 3).

Conclusions

With the numbers available in our pilot study, the findings suggest that cyclic stress arising from a wear process or from cyclic compression may trigger the loss of oxidative stability of remelted HXLPE and contribute to synergistically accelerate its progression. Further studies of the effect of cyclic stress on oxidation of remelted HXLPE are needed.

Clinical Relevance

Retrieval studies are warranted to determine the natural history of the in vivo oxidation and wear behavior of first-generation, remelted HXLPE.     

Three-Dimensional Laparoscopic Sleeve Gastrectomy: Improved Patient Safety and Surgeon Convenience

One of the aims of laparoscopic surgery is to improve upon the results obtained by open surgery. This clearly appears to have been achieved in bariatric surgery. Two-dimensional (2-D) systems have been used to date, though new 3-dimensional (3-D) technologies have been introduced in an attempt to improve surgeon vision and thus increase the safety of the surgical techniques. Sixty obese patients underwent sleeve gastrectomy using a device equipped with 3-D optics allowing surgery to be viewed by the surgeon in 3 dimensions by using a specific monitor and wearing appropriate glasses. The mean patient age was 48.1 years. The mean weight was 114 kg (range, 92–172), with a mean body mass index (BMI) of 44 ± 5.21 kg/m². All surgeries were performed using the 3-D system, with a mean surgical time of 71 ± 49.6 minutes and a mean hospital stay of 3.0 ± 1.2 days. Only 1 intraoperative complication was recorded: retroperitoneal bleeding on insertion of the optical trocar. Over a mean follow-up period of 12 months, the mean body weight of the patients was 88 kg (range, 71–121), with a BMI of 30.56 ± 3.98 kg/m² and a percentage excess weight loss of 68.14% ± 7.89%. There was clear improvement of both the blood pressure and glucose levels. Three-dimensional sleeve gastrectomy is safe, viable, and fully reproducible compared with 2-D surgery, improving visualization of the surgical field, safety, and surgeon convenience. Randomized studies involving larger patient samples are needed for the comparison of results.Key words: 3-D laparoscopy, Bariatric surgery, Metabolic surgeryIn recent years, laparoscopic surgery has become clearly indicated in bariatric and metabolic surgery. This surgical technique has made it possible to reduce morbidity and mortality in comparison with conventional open surgery, and to shorten hospital stay. In addition to the usual 5-trocar technique, laparoscopic surgery has also produced satisfactory results with the single-port approach, which is regarded as less invasive and affords equivalent outcomes and improved aesthetic results.More recently, the possibility of using three-dimensional (3-D) surgery has been considered. The film Avatar (James Cameron, 2006) represented a starting point for a number of multinational medical engineering companies who launched projects that now allow us to use 3-D laparoscopic systems. This new technology offers the perception of depth, which was not previously available.Sleeve gastrectomy is one of the surgical techniques presently used to treat obesity. It was initially regarded as first-step surgery in patients with a high body mass index (BMI), before performing biliopancreatic diversion. Sleeve gastrectomy is currently considered to be a restrictive technique that can be used as a sole option in morbid obesity, even when accompanied by diabetes mellitus, as contemplated by the International Sleeve Gastrectomy Expert Panel Consensus of 2011.Three-dimensional laparoscopic sleeve gastrectomy requires 5 ports, like the two-dimensional (2-D) laparoscopic technique, and one of them must be enlarged to extract the sectioned stomach. However, 3-D visualization is very useful in all the surgical steps, as it improves spatial orientation and can increase the safety of the surgical technique.The present study analyzes the results of 3-D laparoscopic sleeve gastrectomy after a short 1-year follow-up period, with a view to evaluating its safety and feasibility in patients with severe or morbid obesity and type 2 diabetes.     

Metastatic lymph node ratio, 6th or 7th AJCC edition: witch is the best lymph node classification for esophageal cancer? Prognosis factor analysis in 487 patients

Background

The esophageal cancer is one of the most common and aggressive worldwide. Recently, the AJCC changed the staging system, considering, among others, the important role of the lymph node metastasis on the prognosis.

Aim

To discuss the applicability of different forms of lymph node staging in a western surgical center.

Methods

Four hundred eighty seven patients with esophageal cancer were enrolled. Three staging systems were evaluated, the 6^th and the 7^th AJCC editions and the Lymph Node Metastatic Ratio.

Results

The majority of the cases were squamous cell carcinoma. The mean lymph node sample was eight. Considering the survival, there was no significant difference between the patients when they were classified by the 7^th AJCC edition. Analysis of the Lymph Node Metastatic Ratio, just on the group of patients with 0 to 25%, has shown significant difference (p=0,01). The 6^th AJCC edition shows the major significant difference between among the classifications evaluated.

Conclusion

In this specific population, the 7^th AJCC edition for esophageal cancer was not able to find differences in survival when just the lymph node analysis was considered.