Modeling and Real-Time Simulation of a Vascularized Liver Tissue

International audienceIn Europe only, about 100,000 deaths per year are related to cirrhosis or liver cancer. While surgery remains the option that offers the foremost success rate against such pathologies, several limitations still hinder its widespread development. Among the limiting factors is the lack of accurate planning systems, which has been a motivation for several recent works, aiming at better resection planning and training systems, relying on pre-operative imaging, anatomical and biomechanical modelling. While the vascular network in the liver plays a key role in defining the operative strategy, its influence at a biomechanical level has not been taken into account. In the paper we propose a real-time model of vascularized organs such as the liver. The model takes into account separate constitutive laws for the parenchyma and vessels, and defines a coupling mechanism between these two entities. In the evaluation section, we present results of in vitro porcine liver experiments that indicate a significant influence of vascular structures on the mechanical behaviour of tissue. We confirm the val- ues obtained in the experiments by computer simulation using standard FEM. Finally, we show that the conventional modelling approach can be efficiently approximated with the proposed composite model capable of real-time calculations

A Concise Review Based on Analytical Method Development and Validation of Apremilast in Bulk and Marketed Dosage Form

Apremilast is used for treatment of psoriasis and psoriatic arthritis. It may also be beneficial for other inflammatory diseases relevant to the immune system. The drug functions as a selective enzyme phosphodiesterase 4 (PDE4) inhibitor and avoids the spontaneous development of TNF-alpha from human synovial rheumatoid cells. The present review assesses the different approaches for evaluation of apremilast in bulk material as well as different formulations. A concise review consists of compile and discuss about over 30 methods for analysing apremilast in the biological matrices, the samples of bulk and in different dosage formulations including HPLC, HPTLC, UPLC, LC-MS and UV-spectrophotometry. A concise review represents the compilation and discussion of about more than 30 analytical methods which includes HPLC, HPTLC, UPLC, LC-MS and UV-Spectrophotometry methods implemented for investigation of apremilast in biological matrices, bulk samples and in different dosage formulations. This detailed review will be of great help to the researcher who is working on apremilast. Keywords: Apremilast; Analytical Profile; HPLC; HPTLC; Bioanalytical; Stability indicatin

The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing.

Microbial ecology is plagued by problems of an abstract nature. Cell sizes are so small and population sizes so large that both are virtually incomprehensible. Niches are so far from our everyday experience as to make their very definition elusive. Organisms that may be abundant and critical to our survival are little understood, seldom described and/or cultured, and sometimes yet to be even seen. One way to confront these problems is to use data of an even more abstract nature: molecular sequence data. Massive environmental nucleic acid sequencing, such as metagenomics or metatranscriptomics, promises functional analysis of microbial communities as a whole, without prior knowledge of which organisms are in the environment or exactly how they are interacting. But sequence-based ecological studies nearly always use a comparative approach, and that requires relevant reference sequences, which are an extremely limited resource when it comes to microbial eukaryotes. In practice, this means sequence databases need to be populated with enormous quantities of data for which we have some certainties about the source. Most important is the taxonomic identity of the organism from which a sequence is derived and as much functional identification of the encoded proteins as possible. In an ideal world, such information would be available as a large set of complete, well curated, and annotated genomes for all the major organisms from the environment in question. Reality substantially diverges from this ideal, but at least for bacterial molecular ecology, there is a database consisting of thousands of complete genomes from a wide range of taxa, supplemented by a phylogeny-driven approach to diversifying genomics [2]. For eukaryotes, the number of available genomes is far, far fewer, and we have relied much more heavily on random growth of sequence databases, raising the question as to whether this is fit for purpose

The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing

International audienceCurrent sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans

The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): Illuminating the Functional Diversity of Eukaryotic Life in the Oceans through Transcriptome Sequencing

Microbial ecology is plagued by problems of an abstract nature. Cell sizes are so small and population sizes so large that both are virtually incomprehensible. Niches are so far from our everyday experience as to make their very definition elusive. Organisms that may be abundant and critical to our survival are little understood, seldom described and/or cultured, and sometimes yet to be even seen. One way to confront these problems is to use data of an even more abstract nature: molecular sequence data. Massive environmental nucleic acid sequencing, such as metagenomics or metatranscriptomics, promises functional analysis of microbial communities as a whole, without prior knowledge of which organisms are in the environment or exactly how they are interacting. But sequence-based ecological studies nearly always use a comparative approach, and that requires relevant reference sequences, which are an extremely limited resource when it comes to microbial eukaryotes

NUMERICAL INVESTIGATION OF STRESS GENERATED IN HIGH PRESSURE HEAT EXCHANGER

Heat Exchangers are used to transfer heat effectively from one medium to another medium. There are several aspects to study the performance of heat exchanger. This paper is concerned with thermo-mechanical issues i.e. thermal expansion due to high temperature and high pressure conditions of U-tube heat exchanger. Tubesheet is very complex part of heat exchanger which expands at high temperature. Due to high temperature difference between shell side and channel side fluids thermal stress are generated in the tubesheet which effects on the performance of the heat exchanger. 3D FEA model was modeled in ANSYS® to study the thermo-mechanical effect on heat exchanger. Mesh sensitivity analysis was performed to obtain precise results and optimum mesh size. Static structural stress analysis was performed under for two conditions, at first only mechanical loading was studied and secondly mechanical and thermal loading effects were studied. In steady state condition, tubesheet thickness was optimized using 3D parametric model in FEA. The results of the elastic stress analysis were evaluated as per ASME Section VII DIV-2 code limits. It is found that with the optimization design, the tubesheet thickness could be reduced by 20-25% without affecting the safety of the heat exchanger within the allowable limits

The Role of Ligaments: Patient-Specific or Scenario-Specific?

International audienceIn this paper, we present a preliminary study dealing with the importance of correct modeling of connective tissues such as ligaments in laparoscopic liver surgery simulation. We show that the model of these tissues has a significant impact on the overall results of the simulation. This is demonstrated numerically using two different scenarios from the laparoscopic liver surgery, both resulting in important deformation of the liver: insufflation of the abdominal cavity with gas (pneumoperitoneum) and manipulation with the liver lobe using a surgical instrument (grasping pincers). For each scenario, a series of simulations is performed with or without modeling the deformation of the ligaments (fixed constraints or biomechanical model with the parameter of the literature). The numerical comparison shows that modeling the ligament deformations can be at least as important as the correct selection of the patient-specific parameters, nevertheless this observation depends on the simulated scenario