Tribological Performance of Random Sinter Pores vs. Deterministic Laser Surface Textures: An Experimental and Machine Learning Approach

This work critically scrutinizes and compares the tribological performance of randomly distributed surface pores in sintered materials and precisely tailored laser textures produced by different laser surface texturing techniques. The pore distributions and dimensions were modified by changing the sintering parameters, while the topological features of the laser textures were varied by changing the laser sources and structuring parameters. Ball-on-disc tribological experiments were carried out under lubricated combined sliding-rolling conditions. Film thickness was measured in-situ through a specific interferometry technique developed for the study of rough surfaces. Furthermore, a machine learning approach based on the radial basis function method was proposed to predict the frictional behavior of contact interfaces with surface irregularities. The main results show that both sintered and laser textured materials can reduce friction compared to the untextured material under certain operating conditions. Moreover, the machine learning model was shown to predict results with satisfactory accuracy. It was also found that the performance of sintered materials could lead to similar improvements as achieved by textured surfaces, even if surface pores are randomly distributed and not precisely controlled

Intramuscular aripiprazole for the treatment of agitation in schizophrenia and bipolar disorder: From clinical research to clinical practice [Aripiprazolo intramuscolare per il trattamento dell’agitazione nella schizofrenia e nel disturbo bipolare: dalla ricerca alla pratica clinica]

Objectives: To review the major findings of clinical research on the pharmacokinetics, therapeutic efficacy and tolerability of IM aripiprazole as a treatment option for agitation associated with schizophrenia and bipolar I disorder and to provide an expert comment based on the authors' clinical experience in real world psychiatric practice. Methods: Articles on intramuscular aripiprazole published in English between 1997 and 2012 were identified through a MEDLINE search. Relevant clinical studies and review articles were found using the text- and keyword-search term aripiprazole alone and in combination with intramuscular, bipolar, schizophrenia, and agitation. The reference lists of identified articles, especially review articles, were checked for any additional studies that might have been missed in the original MEDLINE search. Results: Acute agitation associated with schizophrenia and bipolar I disorder is a medical emergency that requires prompt pharmacological intervention to relieve patient distress and to prevent harm to self or others. Current guidelines for the management of acute agitation in schizophrenia and bipolar I disorder recommend intervention with antipsychotic agents and/or benzodiazepines, initiated as soon as possible after other conditions leading to agitation have been ruled out. Oral aripiprazole demonstrated efficacy in schizophrenia and bipolar 1 disorder (manic and mixed episodes and maintenance treatment), and resulted associated with a low risk for extrapyramidal symptoms, adverse cardiac effects, hyperprolactinemia and adverse metabolic effects. Intramuscular (IM) formulation of aripiprazole has been approved for treatment of agitation associated with schizophrenia or bipolar I disorder manic. The efficacy of IM aripiprazole in reducing agitation was assessed in two large, multinational, double-blind, placebo-controlled studies in patients with schizophrenia, schizoaffective or schizophreniform disorder 23 24, and in a similarly designed trial in patients with bipolar I disorder. IM aripiprazole was generally well tolerated in the three studies in schizophrenia and bipolar I disorder. The discontinuation rate due to adverse events was generally very low: 0.8% in the aripiprazole group versus 0.5% in the placebo group (pooled analysis). In our clinical practice, the most common reasons for choosing IM aripiprazole (apart from efficacy) are: (1) very low risk of cardiovascular events and heart conduction abnormalities; (2) relatively low risk of EPS; (3) very low risk of excessive sedation; (4) the ability to use concomitant benzodiazepines provided that careful monitoring for orthostatic hypotension is undertaken. Furthermore, based on our clinical experience, IM aripiprazole appears to act more rapidly and be more effective than oral aripiprazole in reducing acute agitation, possibly due to the higher Cmax associated with the IM formulation. However, to our knowledge, oral and IM aripiprazole have not been directly compared in a clinical trial. Conclusions: IM aripiprazole is an effective treatment for agitation in patients with bipolar disorder or schizophrenia and is characterized by a relatively favorable tolerability profile

The use of Powder Metallurgy for promoting friction reduction under sliding-rolling lubricated conditions

This work exploits the use of different sintering manufacturing techniques for obtaining superior performances in lubricated point contacts. Disc and ball specimens were manufactures varying porosity and pore characteristics. The effect of surface pores in sintered materials was evaluated based on the frictional behaviour under different sliding-rolling conditions and lubrication regimes. Furthermore, lubricant film thicknesses were measured using interferometric technique. Test results showed that the decrease of porosity generally improves tribological performance. Low porosity surfaces can promote friction reduction compared to non-porous reference materials in specific configurations and operating with similar specific lubricant thickness values. This work contributes to an improved understanding of how randomly distributed micro-irregularities could change lubrication conditions, potentially increasing the efficiency of lubricated mechanical systems