Weber Criterion Research Articles

Investigating the Characteristics of Injecting and Spraying Methanol-Containing Fuel in a Diesel Engine

Introduction. The operation of eco friendly and high-efficiency internal combustion engines is not possible without deep and comprehensive study of using new types of fuels. That is why, forecasting the indicators of injecting and spraying in a diesel engine running on a mixed alcohol-containing fuel, which have a direct effect on the combustion and formation of toxic components and, as a result, on efficiency and eco friendliness, is an urgent scientific task.Aim of the Study. The study is aimed at developing a theoretical basis for calculating the characteristics of injecting and spraying methanol-containing fuel into diesel engine cylinders that allows optimizing its processes.Materials and Methods. There are considered the characteristics of injecting and spraying alcohol-containing fuel in a diesel engine modified to operate on a mixed methanol-containing fuel. There were used the well-known A.S. Lyshevsky dependencies, which fairly reliably reflect the processes of injecting and spraying in diesel engines.Results. The in-depth studies of the basic principles for evaluating the indicators of injecting and spraying standard fuel made it possible to adapt them for fuels of mixed methanol-containing composition and to investigate the dynamics of changes in the duration and speed of injection, the Weber criterion values, the boundaries between the areas of fuel jet forming, droplet size and spraying angle.Discussion and Conclusion. There has been developed a theoretical basis for calcu­lating the characteristics of injecting and spraying methanol-containing fuel that makes it possible to optimize the operation of a diesel engine running on mixed fuel and, as a result, improve its efficiency and eco friendliness. The presented numerically information on the change in the boundaries of the fuel jet forming areas, the size of the droplets and the angle of the spraying cone allows us to reliably determine the basic parameters of spraying of the used mixed methanol-containing fuels, determine the vector of optimization of the mixing processes and gives insight into the promising directions in designing the geometry of combustion chambers, intake ducts, etc.

Abstract 15269: Effect of a Systemic Right Ventricle With A Biventricular Circulation on Cardiorespiratory Fitness

Background: The clinical care of adults with a systemic right ventricle with biventricular circulation (sRV-biV) is influenced by cardiorespiratory fitness (CRF) evaluation. However, prognostic markers for CRF are derived from analyses of adults with a systemic left ventricle (sLV). While some studies suggest that CRF is lower in adults with sRV-biV compared to those with a sLV, they have not controlled for key clinical characteristics and ventricular function of the systemic ventricle. Research Question: Is CRF lower in adults with a sRV-biV compared to adults with sLV matched for clinical characteristics and systemic ventricular function? Methods: A retrospective cross-sectional comparison of exercise stress test results was performed comparing 24 adults with sRV-biV to 24 adults with a sLV matched for sex (4 females), age (sRV-biV: 46 ± 9 years, sLV: 46 ± 11 years), body mass index (sRV-biV: 28 ± 4 kg/m 2 , sLV: 27 ± 4 kg/m 2 ), ejection fraction of the systemic ventricle (normal: 2, mild: 4, moderate: 11, severe: 7), NYHA class (I: 6, II: 17, III: 1), and doses of diuretics (spironolactone ≤ 25 mg: 24, furosemide ≤ 80 mg: 24 ). Peak VO 2 was compared between groups with Wilcoxon signed-rank tests. Effect sizes are reported as Cohen’s d . Results: Peak VO 2 did not differ significantly between groups (sRV-biV: 20.3 ± 4.2 vs. sLV: 20.9 ± 6.0 mL/kg/min, p=0.43, d =0.18). When patients were dichotomized according to the Weber criterion for optimal versus suboptimal CRF (sLV peak VO 2 > or ≤ 20 mL/kg/min), peak VO 2 was lower in sRV-biV in those with optimal CRF (sRV-biV: 21.0 ± 4.8 vs sLV: 26.6 ± 5.1 mL/kg/min, p=0.006, d =0.72). In contrast, peak VO 2 was greater in sRV-biV in those with suboptimal CRF (sRV-biV: 19.3 ± 3.5 vs. sLV: 16.9 ± 2.0 mL/kg/min, p=0.12, d =NA). Conclusion: Although peak VO 2 values are similar among patients with a sRV-biV and matched controls with a sLV, differences are observed when stratified according to the Weber criteria for optimal CRF. These results may reflect different pathophysiological adaptive mechanisms of a sRV vs sLV. Further studies are required to establish specific prognostic thresholds for patients with sRV-biV.

Experimental study on response law and failure process of slopes in fully weathered granites under precipitation infiltration

To investigate the response law and failure process of slopes in fully weathered granites under precipitation infiltration, a typical fully weathered granite slope is selected for sampling in South China. The physical simulation experimental study of rainfall-induced landslide is conducted, in which Weber criterion is used as the similarity criterion for precipitation. The research results reveal that under precipitation infiltration, the fully weathered granite slope responds quickly. Further, the water content increases sharply, and the matrix suction quickly dissipates. After dissipation, the matrix suction transforms into pore water pressure, which accelerates the deformation of the slope. The wet peak has a large infiltration depth in the slope, and the acceleration of the deep part is lower than that of the shallow part. Under the action of precipitation, the fully weathered granite model undergoes four stages of failure. Firstly, gullies and cracks appear; secondly, cracks propagate and link up; then, the soil on the slope surface swells and ruptures; and finally, the slope slides locally until the entire slope creeps, collapses, and transforms into a “soil flow”. It shows that the landslide will be triggered in fully weathered granite slope by precipitation when the precipitation intensity comes up to 155 mm/d, and the landslide occurs at an accumulated precipitation of 304 mm based on the analysis of precipitation similarity. Overall, the results can provide a reliable theoretical basis and abundant experimental data for the prevention, monitoring, and forecasting of geological disasters in granitic areas.

Determining the quality of milk fat dispersion in a jet-slot milk homogenizer

One of the urgent problems in the dairy industry is to reduce power input in the process of dispersing milk fat while ensuring a high degree of homogenization. This problem can be solved through the development and implementation of a virtually unexplored jet-slot milk homogenizer. The principle of its action implies the preliminary separation of cream from whole milk and its feed into the high-velocity flow of skim milk. The homogenization process occurs by creating a sufficient difference in velocities of the disperse and dispersing phases of the milk emulsion, which is mathematically described by Weber's criterion. Experimental studies of the effect of fat content in cream, cream feed rate, and width of the annular slot on dispersion indices during processing in the designed homogenizer have been carried out. The mathematical dependence which relates these parameters was found. It was proved that to obtain a milk emulsion with a dispersion level of 0.8 μm, the width of the annular slot should be 0.1–0.5 mm, fat content in cream 40–50 %, and the feed rate less than 40 m/s. The results of the evaluation of dispersion quality show a 7 % decrease in the average diameter of the fat globules compared to the most common values obtainable in the valve homogenizer. A refined critical value of the Weber criterion for dispersion of the fat phase of milk was determined (29 units) which indicates an increase in the intensity of the homogenization process in comparison with the jet milk homogenizer with a separate cream feed. The derived critical value of the criterion is necessary to create a theory of the process of dispersing milk fat and develop more efficient designs of milk homogenizers

Research on milk homogenization in the stream homogenizer with separate cream feeding

Homogenization, which is used in the technological schemes of production of most dairy products, is the most energy-intensive of the processes of mechanical processing of milk. One promising way to increase the energy efficiency of homogenization is to use separate homogenization and to use a little-researched stream homogenizer with separate cream feeding. The principle of its action is to pre-divide milk into cream and skim milk, and feed the fat phase with a thin stream into the stream of skim milk. This creates the conditions for achieving the high value of the Weber criterion - the main factor in the dispersion of milk fat. The purpose of these researches is to conduct experimental studies and determine the energy consumption and quality of homogenization of milk after treatment in a stream homogenizer. To achieve this goal, a designed experimental setup was used. The dispersive indices of the milk emulsion were determined by computer analysis of micrographs of milk samples obtained with an optical microscope and a digital camera using Microsoft Office Excel and Microsoft Visual Studio C # software using the OpenCV Sharp library. As a result of experimental studies, the critical value of the Weber criterion for homogenization of milk was determined, which is 28. The regularities of dispersion of milk fat in a stream homogenizer with separate feeding of the fat phase have been established. It is determined that the milk treatment in the experimental homogenizer allows us to achieve an emulsion with an average size of fat globules of about 0.8 μm (at the level of valve homogenizers). The value of the homogenization coefficient is obtained for the disruption of the fat globule in the conditions: subject to a single effect on the emulsion, without the influence of vibration and cavitation. This homogenization coefficient equals 3300 m3/2.s-1.

Can a fibular malunion be corrected by a Z-shaped fibular osteotomy?

The aim of this study was to assess the short-term clinical and radiographic outcomes in patients who underwent realigning Z‑shaped fibular osteotomy. Between January 2007 and December 2014, 28patients with apainful fibular malunion underwent aZ-shaped realignment fibular osteotomy. The mean age was 42.2 ± 14.1 years (range 19.1-67.8 years) and the mean follow-up was 7.0 ± 1.7 years (range 4.0-9.7 years), with no loss to follow-up. Weight-bearing radiographs were used to determine the distal fibula alignment based on Weber's criteria. Degenerative changes of the tibiotalar joint were assessed using the Kellgren-Lawrence scale. Clinical assessment included pain evaluation, measurement of ankle range of motion (ROM), sports activities, and quality of life outcomes. There were no intraoperative or perioperative complications. No delayed unions or nonunions were observed. One patient had radiographic progression of degenerative changes in the tibiotalar joint. Postoperative complications included removal of hardware (n = 15) and arthroscopic tibiotalar joint debridement (n = 2). At the last follow-up the mean visual analog scale (VAS) decreased from 6.5 ± 1.1 to 2.1 ± 1.1 (p < 0.001),the ROM improved from 39º ± 6º to 45º ± 4.5º (p < 0.001), the short form health survey questionnaire (SF-36) physical and mental outcome scores improved from 49 ± 8 to 84 ± 7 (p < 0.001) and from 61 ± 4 to 83 ± 5 (p < 0.001), respectively. The Z‑shaped realignment osteotomy of the distal fibula can provide pain relief and functional improvement in the treatment of fibular malunion. Further studies are needed to address long-term outcomes in this patient cohort.

A Novel Illumination-Insensitive Feature Extraction Method

Image description is a great challenge in the field of computer vision under complex illumination condition. The complex illumination condition is usually unavoidable and unpredictable in real application. In this paper, we propose a novel generalized image descriptor, named as Anisotropy Weber Adapted Symmetric Ternary Pattern (AWASTP), which can overcome the directional inseparability of Weber Local Descriptor (WLD) and invariant threshold of Local Ternary Pattern (LTP). More particularly, we heighten the discriminative effectiveness of image description under complex illumination condition in several ways to restrain the effect of illumination variation. Firstly, a novel selection scheme for scale and angle is proposed. Based on this, an improved anisotropic Laplacian of Gaussian(ALOG) operator model is established by introducing the scale and angle parameter, moreover, an Anisotropic Weber Local Descriptor (AWLD) is presented, which can achieve more rich detailed information of illumination-insensitive feature. Secondly, an Adaptive Symmetric Ternary Pattern (ASTP) algorithm is proposed based on Weber criterion to generate more accurate threshold judgment according to the region characteristics. Thirdly, a two-dimensional AWASTP histogram is created to enhance the discriminative power and represent illumination-insensitive feature description. We conduct many experiments on benchmark databases, such as CMUPIE, FERET, PhoTex, RawFoot, and etc. Experimental results demonstrate the effectiveness of the proposed approach under different illumination conditions.

A comparative analysis of the interaction regimes of two drops and their large population in an aerosol cloud

A comparative analysis of experimental results obtained by different researchers using two different experimental approaches is presented: phenomenological (registration of conditions, characteristics and modes of interaction between a drop of a shell and a target drop) and statistical (analysis of collisions of tens and even hundreds of drops of liquids as part of an aerosol). The ranges of Weber criterion values (the basic parameter used for analyzing the effects of collisions of droplets in a gaseous medium) are established, corresponding to bounce, coalescence, reflexive and stretching separation, disruption, according to the results of all considered experimental research. The bounce of droplets upon collision can be observed under the conditions We = 0.35–0.5; the probability of droplet coalescence is maximum in the range We = 1–7.5; it is possible to reliably predict spreading at We = 15–50; splitting of droplets most often occurs at values We &gt; 50. The probability of occurrence of other scenarios in the selected We ranges is not zero. The conclusion about the need to combine experimental techniques to obtain the most reliable data and their further use in the development of prognostic models is formulated.

Comparative Analysis of Interaction Modes of Two Droplets and of a Large Population in an Aerosol Cloud

A comparative analysis of experimental results obtained by various investigators using two different experimental approaches is presented: the phenomenological approach (the detection of conditions, characteristics, and modes of interaction between a projectile droplet and a target droplet) and the statistical approach (the analysis of collisions of tens and even hundreds of liquid droplets as a part of an aerosol). The ranges of values of the Weber criterion (the basic parameter used for analyzing the effects of collisions of droplets in a gaseous medium), which correspond to recoil, coagulation, expansion, and fragmentation are established according to the results of all experimental works considered.

A model for drop and bubble breakup frequency based on turbulence spectra

In this article, a new Eulerian model for breakup frequency of drops induced by inertial stress in homogeneous isotropic turbulence is developed for moderately viscous fluids, accounting for the finite response time of drops to deform. The dynamics of drop shape in a turbulent flow is described by a linear damped oscillator forced by the instantaneous turbulent fluctuations at the drop scale. The criterion for breakup is based on a maximum value of drop deformation, in contrast with the usual critical Weber criterion. The breakup frequency is then modeled as a function of the power spectrum of Weber number (or velocity square), based on the theory of oscillators forced by a random signal, which can be related to classical statistical quantities, such as dissipation rate and velocity variance. Moreover, the effect of viscosities of both phases is included in the breakup frequency model without resorting to any additional parameter. © 2018 American Institute of Chemical Engineers AIChE J, 65: 347–359, 2019

Realignment osteotomy in fibular malunion

Category: Ankle Arthritis Introduction/Purpose: The incidence of fibula fractures continues to increase. The exact incidence of distal fibula malunions after fibular reconstructions is not known, but incidence up to 33% is described in the literature. The most frequent malunions of the fibula are shortening and malrotation, resulting in the widening of the ankle mortise and talar instability. It has been demonstrated that substantial fibular displacement may substantially increase the contact pressures in the ankle joint. Therefore distal fibular malunion is a risk factor for development of posttraumatic ankle osteoarthritis. The objectives of this study were to (1) describe our treatment algorithm and surgical technique in patients with posttraumatic fibula malunions; (2) determine intra- and postoperative complications rates, (3) to describe mid-term clinical and radiological outcomes and quality of life. Methods: 21 consecutive patients (12 male, 9 female, mean age 42 years) with symptomatic fibular malunions were included into this prospective study. The initial injury was Weber B and C fracture in 7 and 14 ankles. The mean time between the injury and reconstructive surgery was 17.5 months. In all patients a z-shaped osteotomy of the fibula was performed to achieve the appropriate length/rotation of the fibula. Fixation was performed using a plate. If necessary, supramalleolar and inframalleolar deformities were corrected by supramalleolar tibial and calcaneal osteotomies, respectively. Prior to the osteotomies an anterior ankle arthroscopy was performed in all patients. All patients were evaluated pre- and postoperatively (mean follow-up 5.6 years). Radiological outcomes were assessed using standardized weight-bearing radiographs. Clinical outcomes were assessed using visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale, SF-36 questionnaire. Results: There were no intraoperative complications. In two patients early wound healing problems were observed, and resolved with i.v. antibiotics. Osseous healing was observed in all ankles within 10 weeks after surgery. The length and rotation of the fibula was improved in all patients, according to Weber criteria. All patients experienced significant pain relief (VAS: 6.5 ± 1.1 to 1.1 ± 0.9, P &lt; 0.001) and functional improvement (AOFAS hindfoot scale: 47.1 ± 14.5 to 85.0 ± 7.5, P &lt; 0.001; ROM:37° ± 6° to 45° ± 5°, P &lt; 0.001). The SF-36 score also significantly increased in all 8 subgroups. In 11 patients hardware was removed due a discomfort after a mean of 11.7 months (range 7.2 – 22.8). Conclusion: A z-shaped osteotomy is an efficient and successful method to restore fibula length and rotation in patients with posttraumatic malunion. Our findings in this series of 19 ankles confirm that this realignment surgery results in significant pain relief and functional improvement.

On the One-Dimensional Modeling of Vertical Upward Bubbly Flow

The one-dimensional two-fluid model approach has been traditionally used in thermal-hydraulics codes for the analysis of transients and accidents in water–cooled nuclear power plants. This paper investigates the performance of RELAP5/MOD3 predicting vertical upward bubbly flow at low velocity conditions. For bubbly flow and vertical pipes, this code applies the drift-velocity approach, showing important discrepancies with the experiments compared. Then, we use a classical formulation of the drag coefficient approach to evaluate the performance of both approaches. This is based on the critical Weber criteria and includes several assumptions for the calculation of the interfacial area and bubble size that are evaluated in this work. A more accurate drag coefficient approach is proposed and implemented in RELAP5/MOD3. Instead of using the Weber criteria, the bubble size distribution is directly considered. This allows the calculation of the interfacial area directly from the definition of Sauter mean diameter of a distribution. The results show that only the proposed approach was able to predict all the flow characteristics, in particular the bubble size and interfacial area concentration. Finally, the computational results are analyzed and validated with cross-section area average measurements of void fraction, dispersed phase velocity, bubble size, and interfacial area concentration.

Experimental investigations of the parameters of the jet milk homogenizer with separate cream supply

The jet milk homogenizer provides the cream supply in the right amount for normalization of the mixture, grinding of the fat globules and their uniform distribution in the volume of the milk plasma. In the process of technological audit, the following drawbacks are identified: lack of devices to maintain a constant temperature, low resolution of a digital camera and a microscope. In addition, it is necessary to investigate the nature of the influence of the flow and fat content of cream on the average size of fat globules. In order to level out the identified drawbacks, it is planned to increase the time of the experiment in order to exclude the possible influence on the results at the initial and final stages of each experiment. In addition, at the next stage of the study, it is planned to determine the nature of the relationship between cream supply, fat content and average size of fat globules after homogenization. The experimental studies of a jet milk homogenizer with a separate cream supply shows the values of the factors at which the grinding is carried out to the level of valve homogenizers. The average size of fat globules at a level of 0.85 microns is provided with a diameter of the cream supply channel equal to 0.6 mm and the distance of the central channel at the site of the maximal narrowing of 2 mm. It is determined that the nature of the relationship between the skim milk rate is the main factor of grinding and the average size of fat globules is directly proportional. The nature of the relationship between decrease in the size of fat globules is determined as increase in skim milk rate, the nature of which can be explained by an increase in Weber's criterion. Its growth leads to an increase in the magnitude of the tangential stress, the extracted droplet in the ribbon-like body, which subsequently collapses into a large number of small elements. This confirms the hypothesis of destruction when creating the maximum phase rate difference realized in the design of a jet milk homogenizer with a separate cream supply.

Bubble size analysis generated on the submerged orifice, depending on the gas supply mode

A numerical analysis of an algebraic equation of the fifth degree describing the achievement of the diameter of a gas bubble at an aperture is made, the results obtained earlier for limiting cases by simplifying the initial equation and solving it by an analytical method are refined and generalized. With the help of the ratio of the Froude criterion to the Weber criterion, the boundaries of realization of the static, transient and dynamic regimes are established. Approximating formulas are proposed for these regimes, which, with an allowable error in the performance of applied calculations, make it possible to find the value of the detachment diameter of the bubble.

Realignment Osteotomy in Fibular Malunion

Category: Ankle Introduction/Purpose: The exact incidence of distal fibula malunions after fibular reconstructions is not known, but incidence up to 33% is described in the literature. The most frequent malunions of the fibula are shortening and malrotation, resulting in the widening of the ankle mortise and talar instability. It has been demonstrated that substantial fibular displacement may substantially increase the contact pressures in the ankle joint. Therefore distal fibular malunion is a risk factor for development of posttraumatic ankle osteoarthritis. The objectives of this study were to (1) describe our treatment algorithm and surgical technique in patients with posttraumatic fibula malunions; (2) determine intra- and postoperative complications rates, and (3) to describe mid-term clinical and radiological outcomes and quality of life. Methods: 19 consecutive patients (11 male, 8 female, mean age 42 years, range 19 – 68) with symptomatic fibular malunions were included into this prospective study. The initial injury was Weber B and C fracture in 7 and 12 ankles, respectively. The mean time between the injury and reconstructive surgery was 17 months (range 6 – 101). In all patients a z-shaped osteotomy of the fibula was performed to achieve the appropriate length/rotation of the fibula. Fixation was performed using a plate. If necessary, supramalleolar and inframalleolar deformities were corrected by supramalleolar tibial and calcaneal osteotomies, respectively. Prior to the osteotomies an anterior ankle arthroscopy was performed in all patients. All patients were evaluated pre- and postoperatively (mean follow-up 4.9 years, range 3.2 – 6.7). Radiological outcomes were assessed using standardized weight- bearing radiographs. Clinical outcomes were assessed using visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale, and SF-36 questionnaire. Results: There were no intraoperative complications. In two patients early wound healing problems were observed, and resolved with i.v. antibiotics. Osseous healing was observed in all ankles within 10 weeks after surgery. The length and rotation of the fibula was improved in all patients, according to Weber criteria. All patients experienced significant pain relief (VAS: 6.5 ± 1.1 to 0.9 ± 0.8, P &lt; 0.001) and functional improvement (AOFAS hindfoot scale: 48.4 ± 14.5 to 85.7 ± 7.4, P &lt; 0.001; ROM:37° ± 6° to 46° ± 5°, P &lt; 0.001). The SF-36 score also significantly increased in all 8 subgroups. In 11 patients hardware was removed due a discomfort after a mean of 11.8 months (range 7.2 – 22.8). Conclusion: A z-shaped osteotomy is an efficient and successful method to restore fibula length and rotation in patients with posttraumatic malunion. Our findings in this series confirm that this realignment surgery results in significant pain relief and functional improvement.

Results of percutaneous rush pin fixation in distal third fibular fracture: A retrospective study

Aims: Aim of this retrospective study is to evaluate the results of percutaneous rush pin fixation in distal third fibular fractures. Settings and Design: Retrospective study. Materials and Methods: This study was conducted in the Department of Orthopedic Surgery in M. M. Medical College from July 2006 to November 2010. Seventy-eight patients were recruited from emergency and outpatient department, having closed fracture of distal third fibula. Postoperatively all the patients were functionally evaluated as per Kristenson's criteria and the Weber's criteria which included objective criteria, subjective criteria, and radiological evaluation at 3, 6, and 12 months after the surgery. Results: Out of seventy-eight patients, 69 patients underwent union in 90-150 days with a mean of 110.68 days. Touch down weight bearing was started on 2 nd postoperative day. Complications found in four patients who had nonunion, and five patients had delayed union which was treated with bone graft. The results were excellent in 88.46% and good in 6.41% patients. Conclusions: I conclude that the fixation using rush pin in distal third fibular fracture is a safe and effective method of surgery that could be performed easily as well as minimal soft tissue disruption and did not require secondary surgery to remove the wire, and showed sufficient stability after fixation. Therefore, closed reduction and internal fixation with rush rods is one of the good treatment modalities of distal fibular fracture.

Weber on Status Groups and Collegiality: Applying the Analysis to a Modern Organization

Max Weber's legacy includes his ideas about ideal types, status groups and value conflicts that help shape and give meaning to society. This paper uses these conceptualizations to examine Weber's ideal type status group, the Chinese Literate and test it by applying it to a modern group, specifically the Göring Institute, which harbored the German psychotherapy profession during the Third Reich (1933–1945). Weber's description of ancient Chinese Literate society is reiterated because it depicts Weber's “ideal type” status occupation group qualities. Then those qualities are applied to a contemporary organization, the Göring Institute. The way Weber's status group model applies to the Chinese Literate is compared and contrasted to the way the model applies to the Göring Institute. Information about the Göring Institute is drawn from: Psyche and Swastika: Neue Deutsche Seelenheilkunde 1933–1945 (1975), Psychotherapy in the Third Reich (1985), Medicine and Modernity (1997) and Treating Mind and Body (1998) by Geoffrey Cocks. Two findings derived from this comparison are: first, it appears Weber's criteria for his ideal type status group can be applied to a modern group such as the Göring Institute; second, social value conflicts were generated and mitigated by both the Chinese Literati and the Göring Institute. The later finding exemplifies Weber's micro-analysis of class conflict, while the former seems to re-enforce Weber's theory, and Cocks concern, that status groups have more influence in societies that are politically stressed, than in ones that are not.

The Usefulness of Selective Nerve Root Block as a Predictor of Prognosis of Lumbar Disc Herniation

Study Design: A prospective study. Objectives: To investigate the usefulness of selective nerve root block (SNRB) as a prognosis predictor of a lumbar disc herniation. Summary of Literature Review: The biochemical factors of radiculopathy, as opposed to the biomechanical factors, are more reversible and responsive to a corticosteroid injection. Materials and Methods : Fifty patients underwent SNRB for the radiculopathy caused by a herniated lumbar disc and were followed for at least 1 year. The straight leg raising (SLR) angle, visual analog scale (VAS) and the patients' subjective satisfaction, using the Weber criteria, were initially investigated, and again at 1 week and 1 month after the procedure, and finally at the final follow-up. The patients were divided into two groups according to the final satisfaction. Group 1 (satisfactory prognosis, N=32) had Excellent/Good results at the final follow-up, whereas Group 2(unsatisfactory prognosis, N=18) had Fair/Poor final results, or underwent surgical treatment. The improvements in the SLR and VAS at 1 week and 1 month were compared between two groups. The subjective satisfaction each time was compared to the final outcome; the relative risks were also calculated. Results: The improvements in the SLR and VAS for Group 1 were significantly better than those for Group 2 at both 1 week and 1 month (P<0.05). Those patients with Excellent/Good results at 1 week and 1 month manifested satisfactory final outcomes (P<0.05). The risks of the patients with Fair/Poor results at 1 week and 1 month manifesting unsatisfactory final outcomes were 6.8 and 15.2 times higher than those with Excellent/Good results. Conclusion: Selective nerve root block could be a useful method, not only to relieve acute leg pain, but also to predict the longterm prognosis of a herniated lumbar disc. Early surgical treatment could be considered for the patients not manifesting significant improvement until 1 month after SNRB.

FEATURES OF THE FORMATION OF ENDOGENIC INOCULANTS IN THE METAL STREAM DURING THE CASTING OF LARGE INGOTS

One promising method of controlling the structure of the metal in the production of ingots and large castings is the introduction of highly dispersed cooling particles - inoculants - into the melt. The iron powders used for this purpose are not always compatible with the chemical composition of the alloy which is being made. In addition, the outside surface of the inoc- ulants which are introduced may be oxidized. This diminishes the positive effect of the cooling additives on the crystallizati on of the ingot or casting. A more efficient approach would be to form drops inside the metal stream during the casting operation . The drops would solidify as they fall in the stream and act as cooling additives having the same chemical composition as the metal being cast. The possibility that an isolated drop will become separated from the stream is determined by many factors, particular- ly the ratio of the external forces acting on the melt and the interfacial forces. An analysis shows that there is little prob ability of a drop separating spontaneously from the melt, due to the strong surface tension of the liquid metal. Additional drops may be formed if individual drops falling about the periphery of the stream are purposedly broken up into smaller fractions. The p os- sibility of such fragmentation taking place is evaluated quantitatively on the basis of a criterion of the deformation of the d rops or Weber's criterion (1). This criterion is a ratio of parameters that are proportional to the aerodynamic flow reaching the drop and to the interfacial forces:

Treatment of displaced pylon fractures with circular external fixators of Ilizarov.

Twenty cases of pylon fractures were treated with IIizarov circular external fixators using the technique of ligamentotaxis. Fourteen men and six women, ranging in age from 20 to 59 years, with open or closed distal tibial fractures were included in this study. The fractures were classified according to the AO system and distributed as seven C1, eight C2, and five C3 fractures. Independent from the type of fracture, six were grade II open according to the Gustilo-Anderson classification. For all fractures, an external fixator was constructed, after reduction by traction and olive wires. Mean follow-up was 29 months. All fractures healed by 14 weeks postreduction. The results were assessed using Weber's criteria: 5 (25%) had excellent results, 10 (50%) good, and 5 (25%) poor results. This technique lowers the rated complications of open reduction and internal fixation, and allows restoration of joint-surfaces, reconstruction of length, and alignment of the extremity while maintaining a sufficient range of motion at the joint. We concluded that use of the Ilizarov circular external fixator enables good results in selected ankle traumas when applied with good indications, planning, and surgical experience.