Close Vessels Research Articles

Comprehensive anatomy of the superior hypogastric plexus and its relationship with pelvic surgery landmarks: defining the safe zone around the promontory.

Pelvic surgery carries an inherent risk of autonomic nerve injury leading to genitourinary and bowel dysfunction due to the close proximity of the superior hypogastric plexus (SHP). The aim of this study was to define the detailed anatomy of SHP and identify its relationship with the vascular landmarks and ureters for pelvic autonomic nerve-preserving surgery. A cadaveric study on the detailed anatomy of the SHP was conducted in our surgical anatomy research unit. Between 02/2019 and 10/2019, macroscopic anatomical dissections were performed on 45 fresh adult cadavers (39 male, 6 female). Distances between the SHP, major vascular structures, and other anatomical landmarks were measured. Three types of SHP morphology were observed: mesh (64.8%), single nerve (24.4%), and fiber (10.8%). SHP bifurcation was located inferior to the aortic bifurcation in all cases; however, it was observed cranial to the promontory in 80% of the cases, whereas 18% were caudally and 2% were over the promontory. The closest vessels to the left and right of the SHP bifurcation were the left common iliac vein (LCIV) (86.2%, the mean distance was 8.49 ± 7.97mm) and the right internal iliac artery (RIIA) (48.2%, mean distance was 13.4 ± 9.79mm), respectively. At SHP bifurcation level, the lateral edge of the SHP was detected on the LCIV in 22 cases and on the RIIA in 10 cases for the left and right side of the plexus, respectively. The distance between the SHP bifurcation and the ureter was 27.9mm on the right and 24.2mm on the left. The width of the left (LHN) and right hypogastric nerves (RHN) were 4.35mm and 4.62mm at 2cm below the SHP bifurcation, respectively. LHN was on the vascular structures in 13 cases, whereas RHN in only 1 case, 2cm below the SHP bifurcation. Understanding the location of the SHP, including its relationship with important anatomical landmarks, might prevent iatrogenic injury and reduce postoperative morbidity in the pelvic surgery setting.

Qualification Testing, Evaluation and Test Methods of Gas Generator for IEDs Applications

In this work, the design qualification testing, evaluation and test methods of gas generator using double base (DB) propellant having square flake shape is explained for an improvised explosive devices (IEDs) applications. Various kinds of the gas generators are used to save life of an aeronaut in the fastest way from the disable fighter aircraft. Due to their ruggedised design, compactness, safe transportation, repeatability in performance and quick operation, the gas generator are used. The gas generator is designed and developed keeping functional, mechanical and structural requirements in mind. The gas generators are subjected to the various qualification tests, electrical characterisation followed by closed vessel (CV) firings at hot and cold temperatures. The gas generators after the successful qualification tests are validated through the ground trials i.e. dynamic firing of disruptor during the development phase. The damage caused due to impact of the projectile is assessed in terms of crater as acceptance criteria at stand-off distance of 0.5 m and 1m. The gas generator discussed in this research article is used to disrupt the suspected IEDs by creating a high-speed jet using water-jet disruptor. In conclusion, after successful qualification testing, the gas generator for IEDs application meets all the specifications as per user’s requirements.

Effects of particle size and content of RDX on burning stability of RDX-based propellants

Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. However, these effects and the corresponding mechanisms are still controversial. In this work, we investigated the physicochemical processes during burning and the corresponding mechanisms through the technologies of structure compactness analysis on the base of voidage measurement and theoretical interfacial area estimation, apparent burning rate measurement using closed vessel (CV) and extinguished burning surface characterization relying on interrupted closed vessel (ICV) and scanning electron microscope (SEM). The results indicate that the voidage increased with the increase of RDX content and particle size due to the increasing interfacial area and increasing interface gap size, respectively. The apparent burning rate increased with the increase of RDX particle size because of the decreasing RDX specific surface area on the burning surface, which could decrease the heat absorbing rates of the melting and evaporation processes of RDX in the condensed phase. Similarly, the apparent burning rate decreased with the increase of RDX content at pressures lower than around 55 MPa due to the increasing RDX specific surface area. Whereas, an opposite trend could be observed at pressures higher than around 55 MPa, which was attributed to the increasing heat feedback from the gas phase as the result of the increasing propellant energy. For propellants containing very coarse RDX particles, such as 97.8 and 199.4 μm average size, the apparent burning rate increased stably with a flat extinguished surface at pressures lower than around 30 MPa, while increased sharply above around 30 MPa with the extinguished surface becoming more and more rugged as the pressure increased. In addition, the turning degree of u-p curve increased with the increase of coarse RDX content and particle size, and could be reduced by improving the structure compactness.

Light Weight Aluminum Cartridge Case Design for IED’s Application - ANSYS

This paper describes the design analysis of the aluminum cartridge case, its testing, Analytical Simulation (ANSYS) and evaluation against Improvised Explosive Devices (IEDs) applications. Aluminum material is light in weight, non-corrosive and compatible with the propellant. Because of excellent properties, it is widely used in defence application sector. In the armament system, an effort is being made to reduce the cost, the weight of material from logistic point of view and its manufacturing process so as to meet the design requirements. Brass cartridge cases are being widely used in various types of ammunition for last 100 years e.g. armaments of small arm cartridges, artillery shell and power cartridges for fighter aircraft. Cartridges are made of either aluminum, steel or brass is filled with the propellants and pyrotechnic composition. With suitable means of ignition, the propellant generates the hot combustion gases at high pressure and temperature. These combustion gases are utilized to perform certain work on the system. The aluminum cartridge case for water disruptor applications plays a significant role in the destruction of the suspicious objects. This paper discusses the design aspects of the aluminum cartridge case for disruptor application of suspected IEDs. Performance evaluation parameters i.e. maximum pressure (Pmax) and time to reach maximum pressure (TPmax) of aluminum cartridge have been carried out in a Closed Vessel (CV) using a Data Acquisition System (DAS). The material properties of aluminum such as tensile strength, percentage elongation and yield strength are determined using a Universal Testing Machine (UTM). Using the data obtained by the above methods, an attempt has been made to determine stress, strain and deformation of the cartridge case theoretically and numerically using ANSYS software. The results obtained by both methods are compared. The results are in good agreement with each other. It is observed that the percentage error for von -Mises stresses is 10.2 % using numerical and theoretical approaches. The percentage error between numerical and theoretical values of the hoop and longitudinal stresses are 6.71 % and 6.78 %. The percentage error between numerical and theoretical values of the hoop and longitudinal strains are 1.36 % and 3.64 %. The errors between theoretical and numerical values for radial displacements are 2.83 %. The novelty in this research work is that the design analysis of aluminium cartridge case is carried out using ANSYS software simulating the real- world problem. The analytical results are compared with numerical results. The actual pressure experienced by the cartridge case generated by the propellant burning is taken into consideration. This pressure is measured by a pressure transducer fitted over a specially designed test rig using a DAS. The sample of aluminum case is tested for hardness and microstructure. The results show there is no significant difference before and after the hardness and microstructure of the material. The results of ANSYS for stress and strain are in good agreement with theoretically calculated results and numerical analysis as percentage error is less than 11. This draws the inference for validating numerical and theoretical results. It is seen that 57.352 % saving in weight using aluminum cartridge is achieved. Using ANSYS, hoop stress 382.7 MPa, Hoop strain 4.32x10-3, longitudinal strain 0.8602x10-3 and longitudinal stress 191.5 MPa are estimated. The main objective of this paper is to carry out design and analysis of aluminum cartridge case analytically as well as numerically.

Development of zirconium and potassium perchlorate igniter for AP/HTPB composite propellant base bleed grain

For effective and reliable ignition of ammonium perchlorate and hydroxyl-terminated polybutadiene (AP/HTPB) solid composite propellant base bleed (BB) grain a simple, reproducible and high-energy igniter composition were studied. Zirconium and potassium perchlorate (ZPP)-based compositions were developed with and without nitrocellulose (NC) lacquer as binder. The effects of different ratios of Zr/KClO4 were investigated by using fuse wire technique for burning rates, bomb calorimeter for calorific value and high-pressure closed vessel (CV) for pressure–time (P–t) curve, pressure maximum (Pmax), time to reach Pmax (tPmax), and rate of change of pressure change (dP/dt). It was observed that composition K-8 with fuel, oxidizer, and binder ratio of 1:1:0.02 gave reliable burning rate, calorific value, Pmax, and dP/dt. After careful analysis of combustion performance, composition K-8 was further investigated for burning rate and P–t data after 10 h of temperature conditioning at − 40 °C, + 21 °C and + 50 °C, respectively. Selected composition was then press-filled in specially designed steel igniter cups which were press-fitted in base bleed kit igniter bodies. Several static firings were performed by initiating igniter with electric squib for recording the burning time, igniter mass burning behavior, and reproducibility of successful ignition results. ZPP igniter was finally fitted in base bleed kit equipped with AP/HTPB composite propellant BB grain and tested on static as well as dynamic level by firing with 155-mm artillery projectile. Dynamic testing after temperature conditioning of complete projectile equipped with BB kit at + 21 °C, + 50 °C and − 40 °C for 24 h. Igniter provided successful ignition to base bleed grain until it achieved stable burning. All fired rounds achieved enhanced range of 30% approximately, with controlled uniform muzzle velocity and chamber pressure. ZPP igniter is recommended to be used for AP/HTPB solid composite propellant base bleed grain.

Design Analysis of Closed Vessel for Power Cartridge Testing

This paper discusses the design analysis of closed vessel (CV) for power cartridge application in water-jet disruptor. In this article, various design theories are presented in which the vessel is subjected to internal pressure. CV is a kind of pressure vessel utilized to evaluate the performance of power cartridge used for water-jet application. It is a test vessel which generates pressure - time profile by burning the propellant. Energy derived from burning of the propellant of power cartridge aids in neutralizing Improvised Devices (IED's). This energy creates high water-jet plume in the disruptor. In order to evaluate various performance parameters of the cartridge, CV design plays a vital role in the research and development activities, including, development, life trials, production, lot proof trials and life extension / life revision trials. CV is one of the methodologies / techniques from which energy generated is measured in terms of the maximum pressure (Pmax) and the time to maximum pressure (TPmax). This paper also discusses about various design aspects using the finite element method (FEM) and their comparative results with different design theories. In the light of these theoretical, numerical, and experimental works, it was recommended that octahedral stress theory or van Mises theory should be used for vessel design. This satisfies the designer requirements. FEM analysis tool helps in reducing time & development cost.

Pressure-Time Study of Slow Burning Rate Ap/HTPB Based Composite Propellant by Using Closed Vessel Test (CVT)

The Closed vessel (CV) is an equipment used to study the ballistic parameters by recording burning time history, pressure buildup during the process and vivacity of the propellants. It is an apparatus which consists of strong pressure vessel, piezo-electric pressure transducers, sensors and dedicated software. To save time and resources this method is employed instead of dynamic firing while doing research and development of propellants. A measured amount of propellant charge is loaded in the vessel and fired remotely. Ignition is provided by the filament which ignites the black powder charge. In this study, we have used Closed Vessel Tests (CVT) for the first time for recording the ballistic parameters of slow burning composite rocket propellant. We developed a set of composite solid propellant samples containing a mixture of bimodal Ammonium Perchlorate (AP) as an oxidizer, Hydroxy-terminated Polybutadiene (HTPB) as a binder as well as fuel, Dioctyl Sebacate (DOS) as plasticizer, 1-(2-methyl) Aziridinyl Phosphine Oxide (MAPO) as bonding agent and Toluene Diisocyanate (TDI) as curator. Samples were developed by changing the solid loading percentage of bimodal AP particles. By increasing the percentage of AP, the oxidizer-fuel ratio (O/F) increases which effects the ballistic parameters. It is observed that maximum pressure and vivacity increases with increase in solid filler in the propellants. As quantity of AP increases, rate of rise of pressure also increases. CVT firing of each sample was done three times to obtain average burning time and pressure buildup history to evaluate the effect of oxidizer loadings on ballistic parameters of the composite propellant.

An experimental and numerical approach - characterisation of power cartridge for water-jet application

Abstract Power Cartridges are pyrotechnic devices where hot combustion gases utilized to do mechanical work for disruption of suspected Improvised Explosive Devices (IEDs). It plays a vital role either in destroying the suspicious object or making them non-functional by generating the gas pressure on burning of propellant against the water column inside the barrel. Present work is focused on characterisation, numerical solution such as deformation; strain; stress using FEM (Finite Element Method), design qualification, performance and evaluation of power cartridge for disruptor application. Experimental trials for pressure - time (P-t) measurement in closed vessel (CV), various electrical parameters like all fire current (AFC), no fire current (NFC) and ignition delay have been measured. Further, mechanical properties for brass material have been determined. An attempt has been made to characterise the power cartridge by FEM and carrying out the experiments for water-jet application.

Preparation and Properties of a nRDX-based Propellant

The incorporation of nano-scaled cyclotrimethylene trinitramine (nRDX) in nitrocellulose (NC)-based propellants poses processing problems when following conventional methods. Hence, a new preparation method containing a pre-dispersion process was developed, by which 30 mass % RDX (290 nm) was incorporated in the propellant. Meanwhile, the corresponding 290 nm, 12.85 μm and 97.76 μm RDX-based propellants were prepared for comparison using a conventional method. The morphology, structure, ballistic and mechanical properties of the prepared propellants were characterized by scanning electron microscopy (SEM), density analyzer, closed vessel (CV), uniaxial tensile tester and impact tester. The results indicate that the nRDX particles were uniformly dispersed in the NC/NG/TEGDN matrix using the novel method, while agglomerated and recrystallized into large particles with the conventional method. The propellant density increased with decreasing RDX particle size. In particular, the 290 nm RDX-based propellant exhibited a higher burning rate and lower average pressure exponent (α=0.958) compared to the 12.85 μm RDX-based propellant (α=1.043). The tensile strength, elongation at break and impact strength of the RDX-based propellant at −40 °C, 20 °C and 50 °C were dramatically improved by using 290 nm RDX with the novel method.

Intercellular Transport of Nanomaterials is Mediated by Membrane Nanotubes In Vivo.

So-called membrane nanotubes are cellular protrusions between cells whose functions include cell communication, environmental sampling, and protein transfer. It has been previously reported that systemically administered carboxyl-modified quantum dots (cQDs) are rapidly taken up by perivascular macrophages in skeletal muscle of healthy mice. Expanding these studies, it is found, by means of in vivo fluorescence microscopy on the mouse cremaster muscle, rapid uptake of cQDs not only by perivascular macrophages but also by tissue-resident cells, which are localized more than 100 μm distant from the closest vessel. Confocal microscopy on muscle tissue, immunostained for the membrane dye DiI, reveals the presence of continuous membranous structures between MHC-II-positive, F4/80-positive cells. These structures contain microtubules, components of the cytoskeleton, which clearly colocalize with cQDs. The cQDs are exclusively found inside endosomal vesicles. Most importantly, by using in vivo fluorescence microscopy, this study detected fast (0.8 μm s(-1) , mean velocity), bidirectional movement of cQDs in such structures, indicating transport of cQD-containing vesicles along microtubule tracks by the action of molecular motors. The findings are the first to demonstrate membrane nanotube function in vivo and they suggest a previously unknown route for the distribution of nanomaterials in tissue.

Automatic Trajectory Planner for StereoElectroEncephaloGraphy Procedures: A Retrospective Study

In StereoElectroEncephaloGraphy (SEEG) procedures, intracerebral electrodes are implanted in order to identify the epileptogenic zone in drug-resistant epileptic patients. This paper presents an automatic multitrajectory planner that computes the best trajectory in terms of distance from vessels and guiding screws angle, once the candidate entry and target regions are quickly and roughly defined. The planning process is designed also to spare some brain structures, such as cella media and trigone of the lateral ventricles and brain stem. The planner was retrospectively evaluated on 15 patients who had previously undergone SEEG investigation. Quantitative comparison was performed computing for each patient and for each electrode trajectory 1) the Euclidean distance from the closest vessel; 2) the trajectory incidence angle (guiding screws angle); and 3) the sulcality value. The automatic planner proved to satisfy the clinical requirements, planning safe trajectories in a clinical-compatible timeframe. Qualitative evaluation performed by three neurosurgeons showed that the automatically computed trajectories would have been accepted by them.

Close approaches by vessels elicit surface active behaviors by southern resident killer whales

Vessel disturbance is one potential risk factor to the endangered population of southern resident killer whales Orcinus orca. This study was conducted to determine if southern resident killer whales perform surface active behaviors (SABs) in response to close approaches by vessels. Data were collected in the San Juan Islands, USA, and Gulf Islands, Canada, from May through Septem- ber 2005 and 2006. Continuous behavioral data, including the performance of SABs (e.g. spy hops, breaches, tail slaps, pectoral fin slaps), were recorded from southern resident killer whales using a focal follow approach. Distances between the focal whale and nearby vessels were systematically measured throughout each focal follow. In addition, the distance between the nearest vessel and the focal whale was recorded each time the whale performed an SAB. Tail slaps were the most frequently performed SAB. The highest frequency of SABs occurred when the nearest vessel was within 75 to 99 m and 125 to 149 m of the focal whale in 2005 and 2006, respectively. Approximately 70% of SABs occurred when the closest vessel was within 224 m of the whale. Furthermore, a significantly greater proportion of SABs occurred when vessels closely approached whales. Finally, there was a significant temporal relationship between close approaches and the occurrence of SABs; most SABs were per- formed near the time of the closest approach by a vessel. These results suggest that close approaches by vessels elicit behavioral responses in southern resident killer whales and that the minimum approach distance of 100 m in whale-watching guidelines may be insufficient in preventing behav- ioral responses from whales.

Studies on Triple Base Gun Propellant Based on Two Energetic Azido Esters

Triple base propellant is the workhorse propellant because it possesses several advantages like reduced flash, flame temperature, and erosion of the barrel as compared to double and single base propellant. Hence, efforts are going on worldwide to increase its performance by increasing its energy using energetic plasticizers and binders. In the present article, nonenergetic plasticizer dibutyl phthalate (DBP) is replaced by two energetic azido ester plasticizers, tris(azido acetoxy methyl) propane (TAAMP) and bis(azido acetoxy) bis(azido methyl) propane (BABAMP), in triple base composition and their different properties are studied. Experimental closed vessel (CV) results (loading density 0.2 g/cm3) clearly indicate that the triple base composition with 2% DBP has force constant 1018 J/g, which is increased to 1026 and 1030 J/g on replacement of DBP by 1 and 2% TAAMP, respectively. Mechanical properties of propellant compositions containing 1 and 2% TAAMP (compression strength 279 and 291 kgf/cm2, percentage compression 11.2 and 10.5, respectively) are also better than those of composition containing DBP (compression strength 275 kgf/cm2 and 10.3% compression). Similarly, 1 and 2% replacement of DBP by BABAMP shows further rise in energy (1032 J/g, 1038 J/g respectively) than that of compositions containing 1 and 2% TAAMP. These two compositions also exhibit better mechanical properties (compression strength 311.2 and 312.3 kgf/cm2, % compression 11.0 and 10.5, respectively) than compositions containing 1 and 2% TAAMP. The differential thermal analysis (DTA) results brought out the fact that the compositions containing energetic plasticizers revealed maximum decomposition temperature in the range of 172–174°C which is close to DBP plasticized triple base gun propellants (174°C). The energetic plasticized propellant compositions of both (TAAMP and BABAMP) showed sensitivity data in the range of (H50 19 to 22 cm, F of I 25 to 29 and friction insensitivity 19.2 kg) acceptable limit for gun propellant.

1135: Development of a Three-Dimensional Anisotropic Pelvic Lymph Node Clinical Target Volume and Planning Target Volume Using Magnetic Resonance Lymphadenography With Ferumoxtran-10

1135: Development of a Three-Dimensional Anisotropic Pelvic Lymph Node Clinical Target Volume and Planning Target Volume Using Magnetic Resonance Lymphadenography With Ferumoxtran-10

Evolving technology in bipolar perfused radiofrequency ablation: assessment of efficacy, predictability and safety in a pig liver model

Bipolar radiofrequency (RF) ablation, especially with perfusion of saline, has been shown to increase volume over monopolar conventional methods. The aims of this study are to study whether this method is linked to too flattened thermal lesions and premature rise of impedance and to elucidate some safety concerns. Eighteen RF ablations were performed using a 1.8-mm-diameter bipolar applicator in the liver of nine healthy pigs through laparotomy with or without temporary vascular occlusion [the Pringle maneuver (PGM)]: group A (n=9), without PGM; group B (n=9), with PGM. Hypertonic saline solutions (3% and 20 %) were injected through the applicator at a rate of 400 ml/h during the procedure. The pigs were followed up and they were euthanased on the 15th day. Impedance, current, power output, energy output, temperatures, diameters of thermal lesion, volume, sphericity ratio of thermal lesion were correlated among groups. Impedance at the end of the procedure (50.00 Omega+/-28.39 and 52.88 Omega+/-26.77, for groups A and B, respectively) was very similar to the starting impedance (50 Omega). In a median of 1 (range, 0-6) time per RF ablation procedure a reduction of 30 W from the selected power supply was observed during the RF ablation procedure linked to a slight increase of impedance. Volume and short diameter of thermal lesion were 21.28 cm3+/-11.78 and 2.85 cm+/-0.87 for group A, 87.51 cm3+/-25.20 and 4.31 cm+/-0.65 for group B. Continuous thermal between both electrodes were described with a global sphericity ratio of 1.91. One major complication (thermal injury to the stomach) was encountered in a case of cross-sectional necrosis of the targeted liver and attributed to heat diffusion after the procedure. This method has been shown to determine: (1) the relative control of impedance during the procedure; (2) ovoid and relatively large thermal lesions with less dependence upon closest vessels.

Magnetic Resonance Lymphography with Ferumoxtran-10 for Pelvic Lymph Node Target Delineation in Bladder and Prostate Cancer

Purpose/Objective: To determine the utility of Magnetic Resonance Imaging (MRI) with an ultra-small superparamagnetic iron oxide that delineates phagocytotic activity within lymph nodes as a means of lymph node target definition and to examine the patterns of lymph node metastases in prostate and bladder cancer to generate a nodal clinical target volume comprised of the nodal basins at risk of tumor spread. Materials/Methods: A single center trial was undertaken in 40 patients with histologically confirmed prostate (32) or bladder cancer (8). All patients underwent pre- and post- contrast MRI studies over two consecutive days. Axial images were obtained at 3 mm intervals through the pelvis. Ferumoxtran-10 (Combidex®: Advanced Magnetics, Inc, Cambridge, MA) was administered at 2.6 mg Fe/kg on the first day immediately after the initial MRI. The pelvic vasculature and lymph nodes were delineated from the origin of the inferior mesenteric artery to the ischial tuberosities using 3D modeling and image processing software (3D-DOCTOR®: Able Software Corp., Lexington, MA). Lymph node frequency and location relative to the adjacent vascular segments was analyzed. Nodes were ascertained to have metastases using previously demonstrated criteria and with clinicopathologic correlation in those patients undergoing pelvic lymph node dissection (Harisinghani et al. NEJM 2003;348:2491-9). The prostate cancer patients were treated with radiotherapy. However, patients with bladder cancer underwent radical cystectomy and pelvic lymph node dissection, allowing surgicopathologic correlation of the imaging results. Results: 40 patients were enrolled (see Table 1). In the patients with prostate cancer, 39 malignant nodes were identified. Metastases were situated in the following locations or vascular segments: obturator fossa (7); internal iliac (3); external iliac (11); common iliac (5); aortic/aortocaval (3); pararectal (6); and sacral (4). The median number of nodes excised at the time of cystectomy for those patients with bladder cancer was 29 (range 21 to 47). Pathologically, metastases were identified in the following locations or vascular segments: perivesicle (1); internal iliac (8); external iliac (6); common iliac (2); aortic/aortocaval (3); and pararectal (2). On post-contrast MRI imaging, a median of 27 (range 18 to 39) nodes was identified for both bladder and prostate cancer patients within the region occupied by the para-vesical, intercalating, para-rectal, pelvic sidewall, external iliac, common iliac, and pre-sacral lymph node basins. The maximum distance of these lymph nodes from the closest vessel was between 2.5 and 30 mm, with a mean distance of 7.5 mm.Table 1Patient Characteristics Conclusions: The use of MRI lymphography with ferumoxtran-10 provides an objective description of pertinent lymph node locations in a three-dimensional projection for pelvic IMRT and improves the precision of radiation treatment delivery. A uniform radial margin of expansion around the major pelvic vessels fails to adequately encompass all of the parietal and visceral lymph nodes at risk. Ferumoxtran-10 may be useful in the context of IMRT treatment planning as a means of identifying lymph nodes at risk of harbouring occult metastatic disease that should be included in the nodal CTV, and as a means of lowering the threshold for the detection of lymph node metastases that might be treated to a higher dose.

Evaluation of Medicinal Plant Decomposition Efficiency Using Microwave Ovens and Mini-Vials for Cd Determination by TS-FF-AAS

Sample preparation is an important step in the analytical process because it can introduce different error sources. Its efficiency is checked based on the quality and reliability of the data obtained, and the time spent on this task. This work evaluates medicinal plant decomposition parameters using polypropylene mini-vials heated by microwave radiation, applying the single vessel concept. As an example, sample mass amount (5 mg), mixture of oxidant agents (200 µL conc. HNO3+150 µL 30% v/v H2O2), microwave time and power were evaluated by heating 24 mini-vials in both closed-vessel (CV) and focused (F) microwave ovens. In order to achieve the best-optimised condition for sample preparation, cadmium and residual carbon determinations were carried out for all experiments. The residual carbon (between 0.30 and 0.45%) was determined by CHN elemental analysis and the cadmium concentration (up to 0.80 µg g−1) by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) in three different medicinal plants. The accuracy of the proposed methods was assessed using certified reference materials (rye grass, BCR 281 and bovine liver, NIST 1577b) as well as conventional microwave assisted decomposition. The new method used a minimum sample amount (5 mg) and reagent volume (ca. 400 µL) and only 4 and 10 min of microwave sample decomposition for CV and F ovens, respectively. In addition, the capacity of both microwave ovens was increased up to 4 times while contamination risks were inherently reduced with the single vessel concept.

Cellulose Acetate Binder-Based LOVA Gun Propellant for Tank Guns.

Cellulose acetate (CA) binder-based low vulnerability ammunition (LOYA) gun propellant formulations with varying percentages of fine RDX as energetic ingredient have been studied. RDX percentage varied from 76 to 80 in these formulations. An optimised composition with 78 per cent RDX was then studied exhaustively. Ballistic data determined by closed vessel (CV) evaluation and vulnerability aspects obtained by safety tests were then compared vis-a-vis the properties of standard triple base NQ composition. Theoretical prediction and CV test results indicated that the CA binder-based LOVA gun propellant Could satisfactorily meet the ballistic requirements for gun application.

The lack of genital ridge vascularization in the early chick embryo: implications in the migration of the primordial germ cells.

It is known that chick primordial germ cells (PGCs) in early embryonic development migrate via the blood vascular system to colonize the gonadal anlagen. Classically, two factors have been involved in the extravasation of PGCs from the blood stream: chemotactic and mechanical factors. An accurate knowledge of the vascular system of the genital ridge is therefore necessary. However, development of gonadal vascularization in bird embryos has been scarcely studied. Our previous studies have shown that the gonadal arteries develop from the mesonephric arteries. The purpose of this work was to study the implications of the development of the vascular system of the chick genital ridge on PGCs colonization. We selected the Hamburger and Hamilton (H-H) stage 18, since the genital ridge is well developed and PGCs actively extravasate. Forty chick embryos of this stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point-dried specimens as well as light microscopy. Our results are conclusive. We could not find any vessel or capillary network supplying the genital ridge; the dorsal aorta and the primordia of the mesonephric arteries were the closest vessels. However, numerous interendothelial spaces were found in the dorsal aorta at the level of the genital ridge. It is suggested that the interendothelial gaps may be very important in the exchange of substances between the avascular genital ridge and the aortic endothelium at this developmental stage. Two different routes are thought to be involved in PGC migration to the gonadal anlage at this stage: the aortic endothelium and the mesonephric arteries. Whereas mechanical factors may be important for extravasation of PGCs in the mesonephric arteries, no reasons have been found from the morphological point of view to support a slowness of the blood flow in the dorsal aorta at the level of the genital ridge facilitating the extravasation.

The lack of genital ridge vascularization in the early chick embryo: Implications in the migration of the primordial germ cells

It is known that chick primordial germ cells (PGCs) in early embryonic development migrate via the blood vascular system to colonize the gonadal anlagen. Classically, two factors have been involved in the extravasation of PGCs from the blood stream: chemotactic and mechanical factors. An accurate knowledge of the vascular system of the genital ridge is therefore necessary. However, development of gonadal vascularization in bird embryos has been scarcely studied. Our previous studies have shown that the gonadal arteries develop from the mesonephric arteries. The purpose of this work was to study the implications of the development of the vascular system of the chick genital ridge on PGCs colonization. We selected the Hamburger and Hamilton (H-H) stage 18, since the genital ridge is well developed and PGCs actively extravasate. Forty chick embryos of this stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point–dried specimens as well as light microscopy. Our results are conclusive. We could not find any vessel or capillary network supplying the genital ridge; the dorsal aorta and the primordia of the mesonephric arteries were the closest vessels. However, numerous interendothelial spaces were found in the dorsal aorta at the level of the genital ridge. It is suggested that the interendothelial gaps may be very important in the exchange of substances between the avascular genital ridge and the aortic endothelium at this developmental stage. Two different routes are thought to be involved in PGC migration to the gonadal anlage at this stage: the aortic endothelium and the mesonephric arteries. Whereas mechanical factors may be important for extravasation of PGCs in the mesonephric arteries, no reasons have been found from the morphological point of view to support a slowness of the blood flow in the dorsal aorta at the level of the genital ridge facilitating the extravasation. Anat. Rec. 251:398–405, 1998. © 1998 Wiley-Liss, Inc.