Background:Endoscopic biopsy of brain tumors is an important part of the armamentarium of management of intra- and periventricular tumors that is generally considered an acceptable and, in some situations, a preferred method for tissue sampling. The diagnostic yield of the procedure has been variably reported. Technical aspects of the procedure should undoubtedly reflect on its success rate and accuracy. Such impact on diagnostic yield of endoscopic brain biopsy is infrequently discussed in the literature.Methods:A search of the medical literature was conducted for publications on endoscopic brain biopsy. These reports were analyzed regarding the various technical aspects.Results:In the 43 publications analyzed, lenscopes were exclusively used in 22 reports and a tissue diagnosis was possible in 362 out of 387 endoscopic biopsies with a diagnostic yield of 93.54%. Only fiberscopes were used in 8 reports and a tissue diagnosis was possible in 100 out of 132 endoscopic biopsies with a diagnostic yield of 75.76%. The diagnostic yield in the mixed and unspecified groups was 88.95 and 88.04%, respectively. Very few details on the histopathological methods and tumor molecular genetics could be found.Conclusion:Endoscopic biopsy of brain tumors has a higher diagnostic yield when lenscopes are used. Neuronavigation seems to add to the diagnostic accuracy of the procedure. Studies detailing molecular genetic features of biopsied tumors are necessary in the future.

The effect of fuel equivalence ratio Φ on the start of combustion (SOC) and emissions in a homogeneous charge compression ignition (HCCI) engine has been studied using methane CH4 as surrogate of natural gas (NG) fuel. To enable the use of natural gas in HCCI engines, higher compression ratios is required to ensure the auto-ignition. For this purpose, a 0 D multi-zone thermo-kinetic model was adopted with 10 zones using the CHEMKIN-PRO software. Only the closed portion of the cycle (from IVC to EVO) was simulated and no valve event or gas exchange process is considered in this model. The investigation was performed on a four-stroke single cylinder engine running at a fixed speed of 800 rpm. The operating conditions of the engine used in this work were an IVC pressure and temperature of 1.6 bar and 417 K respectively, compression ratio of 18.8:1, with varying fuel equivalence ratio Φ from 0.20 to 0.45 by step of 0.05. Since pressure and temperature profiles plays a very important role in reaction path at certain operating conditions, an attempt had been made here to present a complete reaction path investigation and absolute rate of production (ROP) on the formation/destruction of chemical species at peak temperature and pressure conditions in the first zone #1, middle zone #5 and last zone #10 for Φ = 0.20 and Φ = 0.45.