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.     

Preoperative Carcinoembryonic Antigen and Prognosis of Colorectal Cancer. An Independent Prognostic Factor Still Reliable

To evaluate whether, in a sample of patients radically treated for colorectal carcinoma, the preoperative determination of the carcinoembryonic antigen (p-CEA) may have a prognostic value and constitute an independent risk factor in relation to disease-free survival. The preoperative CEA seems to be related both to the staging of colorectal neoplasia and to the patient''s prognosis, although this—to date—has not been conclusively demonstrated and is still a matter of intense debate in the scientific community. This is a retrospective analysis of prospectively collected data. A total of 395 patients were radically treated for colorectal carcinoma. The preoperative CEA was statistically compared with the 2010 American Joint Committee on Cancer (AJCC) staging, the T and N parameters, and grading. All parameters recorded in our database were tested for an association with disease-free survival (DFS). Only factors significantly associated (P < 0.05) with the DFS were used to build multivariate stepwise forward logistic regression models to establish their independent predictors. A statistically significant relationship was found between p-CEA and tumor staging (P < 0.001), T (P < 0.001) and N parameters (P = 0.006). In a multivariate analysis, the independent prognostic factors found were: p-CEA, stages N1 and N2 according to AJCC, and G3 grading (grade). A statistically significant difference (P < 0.001) was evident between the DFS of patients with normal and high p-CEA levels. Preoperative CEA makes a pre-operative selection possible of those patients for whom it is likely to be able to predict a more advanced staging.Key words: Colorectal carcinoma, Preoperative carcinoembryonic antigen, Disease-free survival, Independent prognostic factorIn the world today, more than 1 million cases of patients with colorectal neoplasia are identified each year. Forty percent of these will have a poor prognosis for which targeted therapeutic strategies could most likely be more effective.^1–3 For this reason, finding prognostic factors that are early, reliable, and related to the extent of the tumor is of the utmost importance. Among these, the most that are considered even to this day are T and N parameters.^1,2,4,5 Less relied upon, however, is the M parameter, which is often understaged due to inadequate pretreatment diagnostic methods.⁶ However, these parameters, which are available to us only after surgery, do not represent the gold standard. In fact, the prognosis of patients with the same staging is often various and that the need to continually implement ever-changing variables in an already excessively fragmented staging is still present.^2,4,7–9Recently, in light of these needs, great attention has been paid to the study of molecular and genetic markers. At present, these markers still have not found a regular application due to the complexity of their determination, the difficulty of standardization and, last but not least, the low cost-benefit ratio.^1,3,4,9,10With this in mind, in our opinion, the carcinoembryonic antigen (CEA) maintains its position, as for over 30 years it has continued to be the most widely used marker¹¹ and whose validity, with regard to colorectal follow-up, has been sanctioned by leading organizations such as the American Society of Clinical Oncology (ASCO)¹² and the European Group on Tumor Markers.¹³ Moreover, as Herrera¹⁴ and Wanebo¹⁵ had already reported by the end of the ‘70s, the preoperative determination of the CEA (p-CEA) seems to be related both to the staging of colorectal neoplasia and to the patient''s prognosis. However, to date, none of this has been conclusively demonstrated and is still a matter of intense debate both in prestigious scientific journals^{4,7,11,16–21} as well as in different guidelines.²²The American Society of Clinical Oncology itself, if on the one hand suggests using the determination of the CEA in the preoperative staging thus justifying a worse prognosis when increased,¹² on the other, does not validate using the p-CEA in the determination of an adjuvant or neo-adjuvant therapeutic strategy.²³Regarding this issue, we believe it still pertinent to evaluate whether in a sample of patients radically treated for colorectal carcinoma, the determination of the p-CEA may have a prognostic value and constitute an independent risk factor in relation to disease-free survival (DFS).