Effects Of Preloading Research Articles

Effects of Preloading of Crystalloid to Prevent Spinal Anesthesia Induced Hypotension in Patient Undergoing Lower Limb Surgery

Effects of Preloading of Crystalloid to Prevent Spinal Anesthesia Induced Hypotension in Patient Undergoing Lower Limb Surgery

Atorvastatin before percutaneous coronary intervention: A systematic review and meta-analysis.

Atorvastatin is widely recommended for long-term secondary prevention in STEMI patients with no contraindication. Although high-dose atorvastatin has been shown to reduce important patient outcomes such as MACE, there is still doubt that high-dose atorvastatin could have the same protective effect in patients undergoing PCI in the short and long term. We searched the following electronic databases: Scopus, Web of Science, MEDLINE, EMBASE, and Cochrane Central considering studies that enrolled adult patients with a confirmed diagnosis of STEMI or NSTEMI undergoing PCI. The intervention must have been atorvastatin alone compared to a placebo, standard care, or a different atorvastatin dose. A total of (n = 11) studies were included in the quantitative analysis. Information on (N = 5,399) patients was available; 2,654 were assigned to receive high-dose atorvastatin therapy, and 2,745 comprised the control group. High-dose atorvastatin pre-loading significantly reduced MACE at one month of follow-up (RR: 0.78; 95% CI: 0.67-0.91; p = 0.014) in both STEMI and NSTEMI. All-cause mortality was reduced in patients with STEMI (RR: 0.28; 95% CI: 0.10-0.81; p = 0.029). The quality of the body of evidence was rated overall as moderate. Patients presenting with STEMI or NSTEMI benefit from high-dose atorvastatin pre-loading before PCI by reducing MACE at 30 days. The use of high-dose atorvastatin in STEMI patients reduced all-cause mortality. The beneficial effects of atorvastatin pre-loading are limited to 30 days post-PCI.

Behavior of high-strength demountable bolted shear connectors in steel-concrete girders with prefabricated slabs

Composite structures with prefabricated concrete slabs and bolted shear studs can enhance the effectiveness and sustainability of construction. In this research, non-shrinkage cement grout is proposed to be filled between high-strength fully threaded bolt shear connectors and a prefabricated slab. Six static push-out tests are performed with different bolt dimensions and different pretension forces on the bolts to study the behavior of bolted shear studs. Finite element models for bolted shear connectors using ABAQUS/Explicit solver are developed, and they matched well with experimental results. Moreover, a Parametric study is conducted to investigate the effects of grout strength, bolt diameter, length-to-diameter ratio, bolt preloading, and bolt material type on the performance of shear connectors. Finally, the results of the parametric analysis are compared to the current design codes and previous researches and more precise equations for predicting the capacity and stiffness of bolted shear studs are proposed.

Rapid response to the editor regarding the journal article 'Acute LDL-C reduction post ACS: strike early and strike strong: from evidence to clinical practice. A clinical consensus statement of the Association for Acute CardioVascular Care (ACVC), in collaboration with the European Association of Preventive Cardiology (EAPC) and the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy'.

With great interest, I read the relevant consensus document led by Konstantin Krychtiuk highlighting the importance of early and aggressive reduction of low-density lipoprotein cholesterol (LDL-C) following acute coronary syndrome (ACS) event to improve clinical outcomes.1 While the ‘strike early and strong’ message is perfectly sound, I would wish to put more emphasis on the window of opportunity for lipid lowering among ACS patients before they receive an invasive management. Authors are to be commended for integrating early lipid lowering in their proposed management pathway; however, the concept of statin ‘pre-loading’ should be put more forward. The mechanisms behind very early statin use in ACS and their translation to clinical benefit are not fully elucidated; however, such effects could be explained by the multifactorial impact of statin treatment on molecular and cellular events that are fundamental to the pathogenesis of ACS. Such mechanisms, independent of the central action on atherogenic lipoproteins, include reduction of inflammation, modulation of thrombogenesis and thrombolysis, improvement of endothelial dysfunction, and amelioration of ischaemia/reperfusion injury.2 It has been previously shown in clinical studies that statin pre-loading before percutaneous coronary intervention (PCI) can limit periprocedural microcirculatory damage, significantly reduce ‘no-reflow’ phenomenon, and can elicit greater endothelial protection in both chronic and acute coronary syndrome populations.3,4,5 These beneficial pharmacodynamic effects of statin pre-loading in patients with ACS might translate to short-term reduction in adverse events, especially those that are coronary-driven.

Enhancing the accumulation level of 3-[18F]fluoro-L-α-methyltyrosine in tumors by preloading probenecid

Introduction3-[18F]fluoro-α-methyl-L-tyrosine ([18F]FAMT) is a promising amino acid tracer targeting L-type amino acid transporter 1 (LAT1). One concern regarding the diagnosis using [18F]FAMT is the possibility of false-negative findings because of its relatively low accumulation level even in malignant tumors. Moreover, preloading probenecid, an organic anion transporter inhibitor, markedly increased the tumor accumulation level of radioiodine-labeled α-methyltyrosine. In this study, we evaluated the usefulness of preloading probenecid in improving the tumor-imaging capability of [18F]FAMT. MethodsThree biodistribution studies of [18F]FAMT were conducted in normal mice to elucidate the usefulness of probenecid preloading. Later, a biodistribution study and positron emission tomography (PET) imaging of [18F]FAMT were conducted with or without probenecid injection in tumor-bearing mice. ResultsProbenecid preloading significantly delayed blood clearance and consequently enhanced the accumulation of [18F]FAMT in the pancreas, a LAT1-positive organ. The effects of probenecid preloading were independent of the administration route. Tumor accumulation level in the biodistribution study and the maximum standardized uptake value in tumors on PET imaging of the probenecid preloading group were significantly higher than those of the control (without probenecid injection) group in tumor-bearing mice. ConclusionsPreloading probenecid significantly delayed blood clearance and consequently enhanced the accumulation of [18F]FAMT in tumors. These results indicate that preloading probenecid could improve the diagnostic accuracy of [18F]FAMT.

Performance deterioration of fly ash/slag-based geopolymer composites subjected to coupled cyclic preloading and sulfuric acid attack

Coupled effects of cyclic preloading and sulfuric acid attacks on the performance deterioration of fly ash/ground granulated blast furnace slag (GGBFS) geopolymer mortar (GPM) were investigated in this study. Ordinary Portland cement mortar (OPM) was also prepared as the control for comparison. The testing parameters include visual appearance, mass change, compressive strength, degradation depth, microstructure and leaching behavior after exposure to sulfuric acid solutions. Before the exposure to sulfuric acid solutions, compressive strength of GPM was increased with the addition of GGBFS, but more strength reduction was caused by cyclic preloading compared to the OPM. On the other hand, after the exposure to different sulfuric acid attacks, GPM with higher content of GGBFS experienced server deterioration after preloading. Cyclic preloading probably caused microcracks or damages in mortars, thus increasing the probability of sulfuric acid deterioration. Although GPM exhibited more strength reduction due to preloading than the OPM, after 18-month exposure to sulfuric acid attacks, GPM with preloading still performed better than the corresponding OPM. Similarly, the corresponding GPM exhibited a lower mass loss and degradation depth compared to the OPM under the same conditions. This implies that the higher content of CaO in GGBFS and OPC increase the formations of ettringite and gypsum, which lead to more expansion and severer cracks and damages. Compared with the calcium silicate hydrate (C-S-H) gels in OPM, there are higher Al/Si ratios but lower Ca/Si ratios of cross-linked aluminosilicate polymer gels in GPM. Therefore, GPM exhibited less severe deterioration even with exposure to sulfuric acid attacks though.

Effects of Eccentric Pre-loading on Concentric Vertical Jump Performance in Young Female Athletes

This study examined changes in vertical jump performance with progressively greater eccentric pre-loading in relation to growth and development in young female athletes. Twenty young female athletes ranging from 9 to 17 years old performed the following vertical jumps in random order: static jumps (SJs), counter-movement jumps (CMJs), and drop jumps (DJs) from drop heights of 20, 30, and 40 cm (DJ20, DJ30, and DJ40, respectively). Measurements included peak force (PF), peak rate of force development (RFD), peak power (PP), eccentric impulse (ECC), and concentric impulse (CON). Measurements of growth included age, maturity offset, height, body mass, fat-free mass, and thigh muscle cross-sectional area (CSA). PF increased from the SJ-DJ20 (P ≤ 0.009), then plateaued from DJ20-DJ40 (P = 1.000). RFD remained the same from SJ-CMJ (P = 1.000), increased from CMJ-DJ20 (P < 0.001), and plateaued from DJ20-DJ40 (P = 0.874). PP increased from the SJ-CMJ (P < 0.001), then plateaued from the CMJ-DJ40 (P ≥ 0.486). CON remained the same across all vertical jumps (P = 1.000), while ECC increased from the SJ-DJ40 (P ≤ 0.038). Jump height (JH) increased from the SJ-CMJ (P < 0.001), decreased from CMJ-DJ20 (P < 0.001), and plateaued from DJ20-DJ40 (P = 1.000). The change in PP from the SJ-CMJ (ΔCMJ-SJ) was related to all measurements of growth except CSA (r = 0.558–0.815). Young females produced greater power during the CMJ than SJ, but equivalent power from the CMJ-DJ40, despite increases in ECC. Additionally, ΔCMJ-SJ was not related to CSA, which suggests other underlying mechanisms affect stretch–shortening cycle utilization in young female athletes.

Comparing the Effects of Pre-loading with Gelatine 4% Plasma Volume Expander and 6% Hydroxyethyl Starch Solution Before Spinal Anaesthesia for Lower Limb Orthopaedic Surgery.

BackgroundHypotension is a common complication following spinal anaesthesia. The administration of intravenous fluids prior to spinal anaesthesia, known as pre-loading, has been used to offset the hypotension effect; however, the ideal fluid for pre-loading is still a matter of debate. The objective of this study was to compare the effects of Gelaspan 4% and Volulyte 6% as pre-loading fluids.MethodsA total of 93 patients with American Society of Anaesthesiologists (ASA) physical status I or II having lower limb orthopaedic surgery under spinal anaesthesia were randomised into two groups that received either Volulyte (n = 47) or Gelaspan (n = 46). Before the spinal anaesthesia, these patients were pre-loaded with 500 mL of the fluid of their respective group. Blood samples were taken before pre-loading and again after spinal anaesthesia and sent for venous blood gas and electrolyte level measurement. Baseline and intraoperative records of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR) and the requirement of ephedrine to treat hypotension were also recorded.ResultsBoth fluids could not prevent significant reductions in SBP (P = 0.011), DBP (P = 0.002) and MAP (P = 0.001). There was also significant reduction in HR over time (P < 0.001). There was no significant difference in terms of ephedrine usage between both groups. Neither Volulyte 6% nor Gelaspan 4% caused significant changes in acid-base status.ConclusionThe use of 500 mL of either Gelaspan 4% or Volulyte 6% as pre-loading fluids did not significantly prevent the incidence of post-spinal anaesthesia hypotension following orthopaedic lower limb surgery; however, both were useful in the maintenance normal acid-base balance.

Combined Effects of Vertical Drain and Pre-loading to Reduce The Number Of Geotextile Reinforcement For Road Embankment Design

The study of the behavior of embankments reinforced by geosynthetic construction on soft clay soil with and without a prefabricated vertical drain is described. The effect of a pre-loading with stage construction method to construct the embankment, the gain of bearing capacity, as well as the depth of compressible soil was also considered in this study. The limit equilibrium using Bishop and Fellenius methods was used in this study to determine the stability of the embankment. Vertical drain installation, combined with the stage construction method, substantially reduces the number of geotextile reinforcements needed. The number of geotextiles can be reduced by up to twice that compared with foundation soil without PVD. Furthermore, the combined use of geotextile and PVD can improve the performance of embankment height as well as increase the critical height of the embankment with geotextile reinforcements. Without PVD, the embankment will be safe against landslides (without geotextile) of less than 3.5 meters. When using PVD, the embankment critical height can increase by up to 7 meters. This condition occurs when the embankment is constructed using the stage construction method, geotextile reinforcement, as well as PVD installation for soil improvement.

Effects of Eccentric Preloading on Concentric Vertical Jump Performance in Youth Athletes.

This study measured peak force (PF), peak rate of force development (PRFD), peak power (PP), concentric impulse, and eccentric impulse during static jump (SJ), countermovement jump (CMJ), and drop jump (DJ) in youth athletes to examine changes in vertical jump power with progressively greater eccentric preloading in relation to age, maturity, and muscle mass. Twenty-one males ranging from 6 to 16 years old performed the following vertical jumps in a random order: SJ, CMJ, and DJ from drop heights of 20, 30, and 40cm (DJ20, DJ30, and DJ40, respectively). Measurements included PF, PRFD, PP, eccentric impulse, and concentric impulse for each vertical jump condition. Maturity offset was calculated, while ultrasound images quantified thigh muscle cross-sectional area (CSA). PF and PRFD increased from CMJ to DJ20. PP increased from SJ to CMJ. Concentric impulse remained unchanged, but eccentric impulse increased systematically from across jumps. The change in PP from SJ to CMJ was correlated with age, height, weight, maturity offset, and CSA. The CMJ resulted in the greatest concentric PP with the least amount of eccentric preloading. The inability of young athletes to translate the energy absorbed during the eccentric phase of the stretch-shortening cycle of DJs may be influenced by growth and development.

Design method for concrete columns strengthened with prestressed CFRP sheets

To improve upon the bearing capacities of short circular concrete columns strengthened with carbon fiber reinforced polymer (CFRP) sheets, this paper conducted experimental and numerical investigations to study the influencing factors on the compressive strength of CFRP-strengthened concrete columns, including the preloading of columns, the prestressing applied to CFRP sheets and the number of layers of CFRP sheets. The test columns consisted of an un-strengthened control column in addition to 10 preloaded and non-preloaded columns strengthened in compression with one or two CFRP layers at prestress levels of either 300MPa or 600MPa. These columns were tested under an axial load. The failure modes, stress changes, bearing capacities and load–longitudinal displacement behaviors of the tested specimens were recorded and discussed. Furthermore, the finite element models (FEM) of 10 strengthened columns were developed and validated by comparing the load–longitudinal displacement curves obtained through finite element analysis (FEA) with those retrieved experimentally. A parametric study was subsequently performed using the validated FEM to investigate the effects of preloading, prestressing and the number of CFRP layers. The parametric study demonstrated that the strain lag caused by preloading was negatively related to the compressive strength of the CFRP-strengthened columns. In addition, prestressing could reduce the negative effects of preloading and could improve on the utilization of CFRP tensile strength. Furthermore, the yield load of CFRP-strengthened concrete columns was improved correlative with an increment of the number of layers and the prestress levels of the CFRP sheets. Conversely, whereas the ultimate load only improved with an increment of the number of layers of CFRP sheets, it had no obvious relationship with the prestress levels of the CFRP sheets and was instead related to their ultimate tensile strength. Based on the test data, the bearing capacity formulas for preloaded and non-preloaded short circular concrete columns strengthened with prestressed CFRP sheets were proposed. Subsequently, the presented formulas were confirmed to be reasonably accurate by comparing the bearing capacities calculated numerically with those measured experimentally.

Effects of colloid pre-loading on thromboelastography during elective intracranial tumor surgery in pediatric patients: hydroxyethyl starch 130/0.4 versus 5% human albumin

BackgroundVolume replacement therapy with colloid is still worth studying in major pediatric surgery with potential risk of bleeding. This study assessed the effects of 6% hydroxyethyl starch (HES) 130/0.4 and 5% Human Albumin (HA) on coagulation tested by thromboelastography (TEG) during elective intracranial tumor surgery in pediatric patients.MethodsIn this randomized controlled trial, 60 patients undergoing intracranial tumor resection under general anesthesia were assigned to HES and HA groups (n = 30), and administered preloads of 20 mL · kg−1 HES 130/0.4 and 5% HA, respectively, prior to dura opening. Primary outcomes were perioperative thromboelastography findings, and hemodynamic and hematological parameters. Blood transfusion, perioperative fluid balance, intracranial pressure, mortality, intensive care unit stay, and hospital stay were also assessed.ResultsTEG parameters did not differ after preloading compared to baseline values in either group, except for a decrease in maximum amplitude immediately after infusion (HES group, 57.6 ± 6.0 mm vs. 50.9 ± 9.2 mm; HA group, 60.1 ± 7.9 mm vs. 56.6 ± 7.1 mm; p < 0.01), which was restored to preoperative levels 1 h after fluid infusion. Total perioperative fluid balance, blood loss or transfusion, intracranial pressure, and hematological and hemodynamic variables were similar between both groups (p > 0.05). Mortality, length of hospital stay, and clinical complications were similar between both groups.ConclusionThese findings suggest that HES and HA might have no significant differences regarding coagulation as assessed by TEG during pediatric intracranial tumor surgery with 20 ml/kg volume pre-loading, which can maintain stable hemodynamics and may represent a new avenue for volume therapy during brain tumor resection in pediatrics.Trial registrationChiCTR-IPR-16009333, retrospectively registered October 8, 2016

Measuring dynamic stiffnesses of preloaded distal phalanges in vibration - Test bench validation and parameter study

An experimental vibration test bench was built for measuring the dynamic stiffnesses and dissipated power densities of preloaded distal phalanges undergoing vibration. The aim of this test bench was to analyse the effects of vibration frequency, static preloading, and vibration excitation amplitude on local biodynamic response. Prior to implementation, the test bench was validated by comparison with a tension–compression testing machine and a reference dynamic mechanical analyser. A measurement study was then conducted on a group of 20 subjects. The mean dynamic stiffness showed that the mechanical behaviour of the index finger distal phalanx is similar to that of a complex amorphous polymer: it exhibits frequency-related stiffening with a rubbery plateau, a glassy transition zone, and a glassy state. The static preloading condition considerably modifies the dynamic response of the phalanx, as well as the dissipated power, which is significantly greater when the preloading is high. An amplitude-related softening phenomenon, similar to the Payne effect for rubber, was also revealed. This can be explained by the thixotropic character of the extracellular matrix of the distal phalanx soft tissues. Relevance for industryExtensive exposure of the hand–arm system to regular vibration may lead to various disorders and injuries, due in part to changes in mechanical quantities, such as dynamic stress, strain, or dissipated power density, arising from the propagation of such vibration. Nowadays, the direct measurement of this biodynamic response inside soft tissues is still extremely challenging. A way to assess the overall mechanical effects of these local quantities on the human finger is to measure and analyse both the macroscopic stiffness and the dissipated power of fingers.

Behaviour of steel-jacket retrofitted RC columns with preload effects

Steel jacketing is an efficient way to retrofit reinforced concrete columns. Previous studies focused on the performance improvement without considering the preloads on the original columns. The preloads might inevitably affect the structural performance of the retrofitted columns. Comprehensive experimental and numerical studies on the behaviour of steel-jacket retrofitted RC columns with preload effects are presented in this paper. Twenty-nine steel jacketing columns with different steel tube thicknesses, axial preloading levels and load eccentricities are tested under concentrically or eccentrically compressive loading.The experimental results are discussed and illustrate that the effects of preloading levels on the axial compression strength of the retrofitted columns are negligible while increasing the preloads could decrease the eccentric compressive strength. A fibre element model is developed to predict the behaviour of the retrofitted columns. The material non-linear behaviour of all the components considering the steel tube and stirrup confining effects on the concrete as well as the preloading action are taken into account in the model. The model is validated by comparing its results with the experimental results. Extensive parametric studies are undertaken by using the proposed numerical model to elucidate the effects of axial and moment preloading and the effects of preloads with various other parameters on the performance of the retrofitted columns.

Comparison of the effects of pre loading with 6% hydroxy-ethyl starch 130/0.4 versus Ringer lactate in preventing spinal anaesthesia induced hypotension in Caesarean section

Background: Hypotension after spinal anaesthesia is preventable by adequate pre-loading with colloids or crystalloids. Women posted for emergency caesarean section are more vulnerable for hypotension as they are not preloaded adequately due to time constraints. The idea of the study is to maintain haemodynamics by administering preload solution without any delay. Here 6% Hydoxyethyl starch (HES) is compared with Ringer lactate (RL) as a preloading solution. Materials and Methods: 50 pregnant women posted for emergency caesarean section were randomly allocated into 2 groups – Group H of 25 women received 500 ml of 6% HES and Group R of 25 women received 500 ml of RL intravenously as preload prior to spinal anaesthesia. The requirement of ephedrine to counter hypotension and the changes in the haemodynamic parameters were noted. Statistical analysis was done using Student’s ‘t’ test, Fisher’s test and Chi square test, and p

Effects of hypertonic saline preloading in sub arachnoid blockade for transurethral resection of prostate - A comparative study

Background: Hypertonic solution is used to combat hypotension in sub-arachnoid block during trans urethral resection of prostate. Aims and objectives: To compare the effect of 3% sodium chloride solution with that of 0.9% sodium chloride solution, to combat sub-arachnoid block induced hypotension in trans urethral resection of prostate. Methods: A total number of sixty patients ASA grade I &amp; II were selected randomly in two groups , thirty in each group. Group A received 15ml/kg of 0.9% NaCl solution and group B 4ml/kg of 3% NaCl solution as a preload. Sub arachnoid block performed at the L3/4 interspace in the sitting position. Heart rate, mean arterial pressure, amount of ephedrine, amount of used additional I/V normal saline, serum electrolytes and level of sensory block were observed. Results: Mean arterial pressure was differed significantly at late hours ie, 50min, 60min (P&lt;0.001). Incidence of hypotension was 43% in group A, 16% in group B and was significant (p&lt;0.05). Less additional I/V fluid was required in group B and difference was significant (P&lt;0.05). Low doses of ephedrine was needed in group B and was highly significant (P&lt;0.001). Conclusion: Preloading of hypertonic solution is superior to isotonic solution in trans urethral resection of prostate under sub arachnoid block. DOI: http://dx.doi.org/10.3329/jbsa.v22i2.18145 Journal of BSA, 2009; 22(2): 66-71

Theoretical modelling of post - buckling contact interaction of a drill string with inclined bore-hole surface

At present, the time of easy oil and gas is over. Now, the largest part of fossil fuels is concentrated in the deepest levels of tectonic structures and in the sea shelves. One of the most cumbersome operations of their extraction is the bore-hole drilling. In connection with austere tectonic and climate conditions, their drivage every so often is associated with great and diversified technological difficulties causing emergencies on frequent occasions. As a rule, they are linked with drill string accidents. A key role in prediction of these situations should play methods of theoretical modelling. For this reason, there is a growing need for development and implementation of new numerical methods for computer simulation of critical and post-critical behavior of drill strings (DSs). In this paper, the processes of non-linear deforming of a DS in cylindrical cavity of a deep bore-hole are considered. On the basis of the theory of curvilinear flexible rods, non-linear constitutive differential equations are deduced. The effects of the longitudinal non-uniform preloading, action of torque and interaction between the DS and the bore-hole surface are taken into account. Owing to the use of curvilinear coordinates in the constraining cylindrical surface and a specially chosen concomitant reference frame, it became possible to separate the desired variables and to reduce the total order of the equation system. To solve it, the method of continuation the solution by parameter and the transfer matrix technique are applied. As a result of the completed numerical analysis, the critical states of the DS loading in the cylindrical channels of inclined bore-holes are found. It is shown that the modes of the post-critical deforming of the DS are associated with its irregular spiral curving prevailing in the zone of bottom-hole-assembly. The possibility of invariant state generation during post-critical deforming is established, condition of its bifurcation is formulated. It is shown that infinite variety of loads can correspond to one geometrical configuration of the DS. They differ each from other by contact force functions.

Effects of l-DOPA pre-loading on the uptake of boronophenylalanine using the F98 glioma and B16 melanoma models

The present study was undertaken to evaluate the effects of l-DOPA pre-loading on the uptake of BPA using the F98 rat glioma and the murine B16 melanoma models. In vitro pretreatments of F98 glioma and B16 melanoma cells with l-DOPA, followed by exposure to BPA increased boron uptake, as determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Based on this, in vivo studies were initiated in F98 glioma bearing rats. Initially, the l-DOPA dosing paradigm was evaluated. Maximum tumor boron uptake was observed following i.p. administration of l-DOPA (50mg/kg) followed 24h later by BPA (31.8±8.9 vs. 17.2±6.3µg/g for BPA alone). Next, the effect of l-DOPA pre-loading as a function of the route of administration of BPA was evaluated in F98 glioma bearing rats. The greatest increase in uptake was seen following i.v. administration of BPA, while in contrast no significant increase was seen following intracarotid (i.c.) administration (38.6±12.4 vs. 34.2±10.9). Cellular localization of the F98 glioma, as determined by secondary ion mass spectrometry (SIMS) boron imaging revealed equivalent tumor boron concentrations following l-DOPA pre-loading. In vivo studies in B16 melanoma bearing mice showed equivalent tumor boron values in treated and untreated mice, suggesting that the effects of l-DOPA pre-loading may depend both on the histologic type of tumor and its anatomic site.

Radial consolidation model incorporating the effects of vacuum preloading and non-Darcian flow

A modified 150 mm Rowe cell equipped with pore water pressure measurement was used to capture the flow relationship during vacuum-assisted radial consolidation. Based on the measured data, a radial consolidation model incorporating the effects of vacuum preloading is proposed, based on a non-linear relationship between the flow velocity and hydraulic gradient. The predictions of the proposed consolidation model are then compared with the predictions based on Hansbo's Darcian and non-Darcian models. The agreement between the proposed model and the measured data is shown, and the advantages of the proposed model compared with the existing models are discussed. An embankment case history taken from the reclamation project at the Port of Brisbane, Australia, was analysed, based on the current solution, and compared with the field measurements.

Free vibrations of drill strings in hyper deep vertical bore-wells

This paper considers the problems on investigation of the dynamic bending of elongated drill string tubes studied with allowance made for destabilizing effects of the longitudinal non-uniform preloading, action of torque, inertia forces of rotation and internal flows of washing liquid (mud). As a result of the completed analysis, natural wave and vibration modes are constructed, their frequencies are calculated. It is shown through the study of appropriate dispersion equations that free bending vibrations of unbounded rods can be realized only in the modes of regular dextral and sinistral spiral waves propagating with different velocities in different directions. The modes of free vibrations of the bounded drill strings possess more complicated irregular spiral shapes.