bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport of deslorelin, an LHRH agonist, is vectorial and exhibits regional variation in excised bovine nasal tissue
Authors: Koushik Kavitha N , Kompella Uday B
Published: July 2004

The nasal route is a non-invasive alternative route for the delivery of a number of macromolecules, including peptides, proteins and vaccines. The purpose of this study was to determine the regional variation in excised bovine nasal tissue permeability to deslorelin, a nonapeptide luteinizing hormone releasing hormone (LHRH) agonist, and to further elucidate its mechanisms of transport. To this end, this study determined the permeability of deslorelin across different regions of freshly excised bovine nasal mucosa, including the medium turbinate anterior (MTA), medium turbinate posterior (MTP) and the inferior turbinate posterior (ITP) regions. At 37°C, mucoal-to-serosal (m-s) transport of deslorelin across excised bovine nasal mucosa exhibited regional variation, with the % cumulative transport in 6 h being in the order: MTA (0.2 ± 0.06%) < MTP (1.6 ± 0.1%) < ITP (2.85 ± 0.3%). In addition, at 37°C, deslorelin transport across all these nasal regions was vectorial and the mucosal-to-serosal:serosal-to-mucosal (m-s:s-m) transport ratios across MTA, MTP and ITP regions were 1.5, 5.4 and 3.7, respectively. At low temperature (4°C) and at 37°C in the presence of 2,4-dinitrophenol, an energy depletor, the m-s deslorelin transport across the MTP region decreased to 0.32 ± 0.12 and 0.13 ± 0.05%, respectively, and the directionality was abolished. Sodium fluorescein transport also exhibited regional variation but no directionality. Histology and scanning electron microscopy studies indicated non-ciliated columnar epithelium in the MTA region and ciliated respiratory epithelium in the MTP and ITP regions. The thickness of the various regions, as visualized using histology, was in the order: MTA > MTP > ITP. Thus, deslorelin transport across excised bovine nasal mucosa is vectorial, temperature- and energy-dependent and exhibits regional variation. The regional differences in s-m transport are likely due to differences in the passive transport. Differences in m-s:s-m flux ratios may be due to differential expression of carriers.
Effects of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice
Authors: Yamaki Kouya , Li Xiaojuan , Uchida Hiroyuki , Alam A H M Khurshid , Hossain Md Aslam , Yanagisawa Rie , Takano Hirohisa , Taneda Shinji , Hayashi Hideyuki , Mori Yoki , Yoshino Shin
Published: July 2004

The present study was designed to investigate the effect of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice. Mice were immunized subcutaneously at the base of the tail with ovalbumin (OVA) emulsified with complete Freund's adjuvant (day 0) and were treated daily with oral administration of various doses of rolipram from days 0 to 20. On day 21, production of anti-OVA IgG and proliferative responses to the antigen were determined. Anti-OVA IgG2a and interferon-γ (IFN-γ), as indicators of Th1 responses, and anti-OVA IgG1 and interleukin-10 (IL-10), as indicators of Th2 responses, were also measured. The results showed that treatment with rolipram failed to affect the production of OVA-specific IgG but decreased the proliferation of spleen cells to the antigen. Its inhibitory effect on these immune responses was correlated with a marked decrease in IFN-γ but not IL-10 production, although neither anti-OVA IgG2a nor IgG1 production was affected by rolipram. These results suggest that rolipram may preferentially inhibit Th1 responses more effectively than Th2 responses. Administration of rolipram resulted in suppression of antigen (OVA)-induced arthritis in mice. The suppression of joint inflammation by rolipram was associated with the inhibition of the OVA-specific proliferative responses of spleen cells and IFN-γ secretion. These results indicate that rolipram may be effective in regulating Th1-mediated diseases such as rheumatoid arthritis.
Inhibitory effect of pyridyloxy- or phenoxylphenoxyalkanate derivatives on rat lens aldose reductase and rat platelet aggregation
Authors: Lim Soon Sung , Shin Kuk Hyun , Jung Sang Hoon , Shin Kye Jung , Kim Dong Chan , Park Sang Woo , Shin Hyun Kyung , Keum Sam Rok
Published: July 2004

The therapeutic potential of aldose reductase inhibitors for the prevention of the secondary complications of diabetes has been extensively reported. On the other hand, the hyperaggregability of platelets in diabetic patients has also been reported as a cause of chronic diabetic complications. The purpose of this study was to develop new compounds with these dual effects from pyridyloxy- or phenoxylphenoxyalkanate synthesized derivatives and examine the effect of their structure-activity relationships on the inhibition of rat lens aldose reductase (RLAR) as well as on platelet aggregation. 2-[4-(2,6-dichloro-3-methyl-phenoxy)-3-nitro-phenoxy]-propionic acid (3) exhibited the most potent inhibitory effect (IC50 = 3.0 ± 0.21 μM), comparable to tetramethylene glutaric acid (IC50 = 6.1 ±0.2 μM), which is used as a positive control on RLAR, and showed potent inhibitory activities on rat platelet aggregation induced by ADP and collagen (IC50 = 0.093 ± 0.01 and 0.032 ± 0.01 μM, respectively) comparable with aspirin (IC50 = 0.15 ± 0.05 and 0.047 ± 0.01 μM, respectively), used as a positive control.
Vasorelaxant activities of the putative endocannabinoid virodhamine in rat isolated small mesenteric artery
Authors: Ho W-S Vanessa , Hiley C Robin
Published: July 2004

Virodhamine is a recently identified novel endocannabinoid. Cannabinoids may evoke vasorelaxation through novel receptors in the vasculature and/or through release of vasodilator peptides from sensory nerve endings. Virodhamine induced endothelium-dependent relaxation in the rat isolated small mesenteric artery mounted in a myograph and precontracted with methoxamine. Desensitization of vanilloid receptors by capsaicin did not affect relaxation responses to virodhamine. The CB1 receptor antagonist SR 141716A (3 μM), but not the more CB1-selective blocker AM 251 (1 μM), attenuated the response, while two CB2 receptor antagonists, SR 144528 (1 μM) and AM 630 (10 μM), had no effect. The novel antagonist for the putative endothelial ‘abnormal-cannabidiol receptor’, O-1918 (30 μM), inhibited virodhamine relaxations. Hence virodhamine may activate this novel receptor, which might also recognize SR 141716A. Inhibition of nitric oxide synthase (L-NAME 300 μM) did not affect relaxation to virodhamine but the responses were markedly reduced when tone was induced with 60 mM KCl, suggesting a role for the activation of K+ channels. The Ca2+-activated K+ channel (KCa) blockers, apamin (50 nM) and charybdotoxin (50 nM), inhibited virodhamine vasorelaxation. Combination of these blockers with SR 141716A (3 μM) caused no further inhibition. It was concluded that virodhamine relaxes the rat small mesenteric artery by endothelium-dependent activation of KCa, perhaps via the putative abnormal-cannabidiol receptor.
Nanosuspensions: a promising drug delivery strategy
Authors: Patravale V B , Date Abhijit A , Kulkarni R M
Published: July 2004

Nanosuspensions have emerged as a promising strategy for the efficient delivery of hydrophobic drugs because of their versatile features and unique advantages. Techniques such as media milling and high-pressure homogenization have been used commercially for producing nanosuspensions. Recently, the engineering of nanosuspensions employing emulsions and microemulsions as templates has been addressed in the literature. The unique features of nanosuspensions have enabled their use in various dosage forms, including specialized delivery systems such as mucoadhesive hydrogels. Rapid strides have been made in the delivery of nanosuspensions by parenteral, peroral, ocular and pulmonary routes. Currently, efforts are being directed to extending their applications in site-specific drug delivery.
Effect of punch tip geometry and embossment on the punch tip adherence of a model ibuprofen formulation
Authors: Roberts Matthew , Ford James L , MacLeod Graeme S , Fell John T , Smith George W , Rowe Philip H , Dyas A Mark
Published: July 2004

The sticking of a model ibuprofen-lactose formulation with respect to compaction force, punch tip geometry and punch tip embossment was assessed. Compaction was performed at 10, 25 or 40 kN using an instrumented single-punch tablet press. Three sets of ‘normal’ concave punches were used to evaluate the influence of punch curvature and diameter. The punches were 10, 11 and 12 mm in diameter, respectively. The 10-mm punch was embossed with a letter ‘A’ logo to assess the influence of an embossment on sticking. Flat-faced punches (12.5 mm) were used for comparison with the concave tooling. Surface profiles (Taylor Hobson Talysurf 120) of the upper punch faces were obtained to evaluate the surface quality of the tooling used. Following compaction, ibuprofen attached to the upper punch face was quantified by spectroscopy. Increasing punch curvature from flat-faced punches to concave decreased sticking. Altering punch diameter of the concave punches had no effect on sticking when expressed as μg mm−2. The embossed letter ‘A’ logo increased sticking considerably owing to the probable concentration of shear stresses at the lateral faces of the embossed logo.
Cardioprotective effect of tincture of Crataegus on isoproterenol-induced myocardial infarction in rats
Authors: Jayalakshmi R , Devaraj S Niranjali
Published: July 2004

Tincture of Crataegus (TCR), an alcoholic extract of the berries of hawthorn (Crataegus oxycantha), is used in herbal and homeopathic medicine. The present study was done to investigate the protective effect of TCR on experimentally induced myocardial infarction in rats. Pretreatment of TCR, at a dose of 0.5 mL/100g bodyweight per day, orally for 30 days, prevented the increase in lipid peroxidation and activity of marker enzymes observed in isoproterenol-induced rats (85 mg kg−1 s.c. for 2 days at an interval of 24h). TCR prevented the isoproterenol-induced decrease in antioxidant enzymes in the heart and increased the rate of ADP-stimulated oxygen uptake and respiratory coupling ratio. TCR protected against pathological changes induced by isoproterenol in rat heart. The results show that pretreatment with TCR may be useful in preventing the damage induced by isoproterenol in rat heart.
Cytotoxicity studies of Dynasan 114 solid lipid nanoparticles (SLN) on RAW 264.7 macrophages—impact of phagocytosis on viability and cytokine production
Authors: Olbrich Carsten , Schöler Nadja , Tabatt Kerstin , Kayser Oliver , Müller Rainer Helmut
Published: July 2004

Solid lipid nanoparticles (SLN) based on Dynasan 114 (D114) were tested using RAW 264.7 cells. The influence of different surfactants on the cytotoxicity of this type of SLN was examined, expressed as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) viability and the production of cytokines such as interleukin 6 (IL-6), IL-12 and tumour necrosis factor-α (TNF-α). Results were compared with previously obtained data when peritoneal mouse macrophages were used. SLN produced with stabilizers/surfactants such as poloxamer 188, sodium cholate, Lipoid S75, Tween 80, Poloxamine 908 and sodium dodecylsulfate were shown to be nontoxic towards RAW 264.7 cells. Cytokine production was reduced and stimulation, expressed in elevated cytokine levels, could not be found. Using cetylpyridinium chloride (CPC) as stabilizing surfactant, SLN became cytotoxic in a concentration-dependent manner. Not only were the viabilities reduced but also cytokine production. Cytotoxic effects of CPC stabilized SLN could be antagonized using cytochalasin B to block phagocytosis. D114-SLN produced with pharmaceutically accepted surfactants for intravenous injection (poloxamer 188, Lipoid S75, sodium cholate, Tween 80) were very well tolerated by the cells. Even sodium dodecylsulfate-stabilized D114-SLN did not exert toxic effects. Comparison of the RAW 264.7 data with previously obtained data from toxicity studies of D114-SLN towards peritoneal mouse macrophages showed similar results. This offers the possibility of using the RAW 264.7 cell line for cytotoxicity studies of colloidal drug carrier systems, rather than using laboratory animals as source of macrophages for these kinds of studies.
Post-stroke atorvastatin treatment reduces neurological deficits and mortality rate in the stroke-prone spontaneously hypertensive rat
Authors: Hayashi Aska , Suzuki Masanori , Ogawa Yumiko , Sonoda Rie , Sasamata Masao
Published: July 2004

Several large clinical trials have demonstrated that 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors decreased the incidence of stroke independently of their cholesterol-lowering effect. We have investigated the effect of post-stroke treatment with atorvastatin on neurological deficits and mortality in stroke-prone spontaneously hypertensive rats (SHR-SP). The vehicle-treated group showed significantly aggravated neurological deficits compared with those observed on the first day of stroke. In contrast, the post-stroke oral administration of atorvastatin at 3 or 30 mg kg−1/day significantly ameliorated these neurological deficits. Atorvastatin improved the survival rate in a dose-dependent manner, with this effect being significant at 30 mg kg−1/day. Atorvastatin did not affect blood pressure, heart rate or total cholesterol in SHR-SP at either dose. In contrast, it significantly increased plasma nitric oxide (NO) levels at both doses. These results indicated that post-stroke administration of atorvastatin ameliorated neurological deficits and prolonged survival, which might have resulted from increased plasma NO, apart from its effect on cholesterol level and blood pressure in SHR-SP. In conclusion, this study demonstrated the protective effects of post-stroke administration of atorvastatin against stroke in SHR-SP.
Effects of monensin liposomes on the cytotoxicity, apoptosis and expression of multidrug resistance genes in doxorubicin-resistant human breast tumour (MCF-7/dox) cell-line
Authors: Shaik Madhu Sudhan , Chatterjee Abhijit , Singh Mandip
Published: July 2004

We have evaluated the effects of monensin liposomes on drug resistance reversal, induction of apoptosis and expression of multidrug resistance (MDR) genes in a doxorubicin-resistant human breast tumour (MCF-7/dox) cell line. Monensin liposomes were prepared by the pH-gradient method. MCF-7/dox cells were treated with various anticancer drugs (doxorubicin, paclitaxel and etoposide) alone and in combination with monensin liposomes. The cytotoxicity was assessed using the crystal violet dye uptake method. The induction of apoptosis in MCF-7/dox cells was assessed by established techniques such as TUNEL (terminal deoxynucleotidyl transferase-mediated nick end labelling) staining and caspase-3 assay. The effect of monensin liposomes on doxorubicin accumulation in MCF-7/dox cells was monitored by fluorescent microscopy. Finally, the expression of MDR genes (MDR1 and MRP1) in MCF-7/dox cells following the exposure to doxorubicin alone and in combination with monensin liposomes was evaluated by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Our results indicated that monensin liposomes overcame drug resistance in MCF-7/dox cells to doxorubicin, etoposide and paclitaxel by 16.5-, 5.6- and 2.8-times, respectively. The combination of doxorubicin (2.5 μg mL−1) with monensin liposomes (20 times 10−8M) induced apoptosis in approximately 40% cells, whereas doxorubicin (2.5 μg mL−1) or monensin liposomes (20 times 10−8M) alone produced minimal apoptosis (<10%) in MCF-7/dox cells. Fluorescent microscopy revealed that monensin liposomes increased the accumulation of doxorubicin in MCF-7/dox cells. RT-PCR studies demonstrated that the expression of MDR1 and MRP1 was increased by 33 and 57%, respectively, in MCF-7/dox cells following treatment with doxorubicin (2.5 μg mL−1) for 72 h as compared with control MCF-7/dox cells. Furthermore, the levels of MDR1 and MRP1 in MCF-7/dox cells exposed to both doxorubicin and monensin liposomes showed a modest decrease as compared with MCF-7/dox cells treated with doxorubicin alone. In conclusion, the delivery of monensin via liposomes provided an opportunity to overcome drug resistance.
Evaluation of the anti-inflammatory and cytotoxic effects of anthraquinones and anthracenes derivatives in human leucocytes
Authors: Chen Rong-Fu , Shen Yuh-Chiang , Huang Hsu-Shan , Liao Jyh-Fei , Ho Li-Kang , Chou Yueh-Ching , Wang Wen-Yen , Chen Chieh-Fu
Published: July 2004

A variety of anthracene- and anthraquinone-related derivatives, modified from three types of lead structures, including 9-acyloxy 1,5-dichloroanthracene (type I), 1,5-bisacyloxy-anthraquinones with O-linked substituents (type II) and 1,5-bisacyloxy-anthraquinones with S-linked substituents (type III), were synthesized and evaluated by an in-vitro bioassay for their anti-inflammatory and cytotoxic effects in human leucocytes. Among these derivatives, type I compounds displayed potent anti-inflammatory activity against phorbol-12-myristate-13-acetate (PMA)-induced superoxide anion production, a bio-marker of inflammatory mediator production by neutrophils, with 50% inhibition (IC50) concentrations (μM) for compounds 1f, 1g, 1h and 1m being 13.8±3.0, 6.3±4.1, 33.2±1.3 and 33.9±5.7, respectively. Type II and type III derivatives (i.e., 1,5-bisacyloxy anthraquinone-related compounds) and the reference compound, emodin, exhibited relatively minor (20–40%) inhibitory effect against superoxide production by neutrophils. Furthermore, none of these compounds showed a significant cytotoxic effect in human neutrophils. In conclusion, these results suggest that compounds modified from 9-acyloxy 1,5-dichloroanthracence (type I) are more powerful than the other two types as anti-inflammatory drugs. This is the first demonstration that derivatives modified from anthracenes or anthraquinones possess anti-inflammatory activity with no significant cytotoxicity in human neutrophils.
Effect of acyl chains of phosphatidylcholines on the pharmacokinetics of menatetrenone incorporated in O/W lipid emulsions prepared with phosphatidylcholines and soybean oil in rats
Authors: Ueda Kumiko , Fujimoto Masanori , Noto Hiromi , Sakaeda Toshiyuki , Iwakawa Seigo
Published: July 2004

Oil-in-water (O/W) lipid emulsions were prepared with phosphatidylcholines (PCs) of various acyl chains and soybean oil (SO) using a microfluidizer system, and the pharmacokinetics of menatetrenone incorporated in these oil particles were examined at the clinical injection volume (0.1 mL kg−1) in rats. The plasma half-life of menatetrenone incorporated in the oil particles prepared with SO and dipalmitoylphosphatidylcholine (DPPC) (SO/DPPC) was longer than that prepared with SO and egg-yolk phosphatides (EYP) (SO/EYP) by 3 fold, while those of menatetrenone as oil particles prepared with SO and either dilauroyl phosphatidylcholine (DLPC), dimyristoyl phosphatidylcholine (DMPC), distearoyl phosphatidylcholine (DSPC), dioleoyl phosphatidylcholine (DOPC) or dilinoleoyl phosphatidylcholine (DLoPC) (SO/DLPC, SO/DMPC, SO/DSPC, SO/DOPC and SO/DLoPC, respectively) were similar to that of menatetrenone as SO/EYP. The menatetrenone uptake by the liver was not significantly different from that as SO/EYP in all SO/PCs examined, but the menatetrenone uptake by the spleen as SO/DPPC and SO/DSPC was higher than that as SO/EYP. The menatetrenone uptake by the lungs as SO/DPPC was also higher than that as SO/EYP. These findings suggest that SO/DPPC is a good candidate drug carrier for the prolonged plasma circulation of lipophilic drugs.
In-vitro and in-vivo anti-allergic actions of Arecae semen
Authors: Lee Jun Ho , Chang Sung Ho , Park Yun Sim , Her Erk , Lee Hoi Young , Park Jong Woo , Han Jeung Whan , Kim Young Mi , Choi Wahn Soo
Published: July 2004

The effects of various extracts from oriental medicinal herbs on mast cell-mediated allergic reactions have been investigated. Among the extracts, Arecae semen was the most potent inhibitor of antigen-induced degranulation in RBL-2H3 mast cells. A. semen inhibited DNP-BSA- and compound 48/80-induced degranulation in RBL-2H3 mast cells with IC50 values of approximately 53 and 52 μg mL−1, respectively, and inhibited compound 48/80-induced systemic anaphylaxis by 46% at 300 mg kg−1 in mice. A. semen also inhibited the expression of TNF-α and the activation of mitogen activated protein kinase, ERK1/2, which is critical for the production of inflammatory cytokines in mast cells, as indicated by the suppression of the activating phosphorylation of ERK1/2. These results suggest that A. semen may be useful for the treatment of various immediate and delayed allergic diseases.
Biofilm formation and changes in bacterial cell surface hydrophobicity during growth in a CAPD model system
Authors: Hanlon G W , Denyer S P , Hodges N A , Brant J A , Lansley A B , Al-Rustamani W A
Published: July 2004

Peritonitis is a frequent complication of continuous ambulatory peritoneal dialysis (CAPD), with patients suffering recurrent attacks. The microorganisms most frequently implicated in the infection are the skin microflora, in particular, the coagulase-negative staphylococci such as Staphylococcus epidermidis. These microorganisms gain access to the peritoneal cavity via the in-dwelling silicone rubber catheter in the abdominal wall and often persist as biofilms on the surface of the catheter. The surface characteristics of S. epidermidis were monitored during growth in a CAPD in-vitro model together with their ability to adhere to silicone rubber substrata. Fresh dialysis fluid exerted an injurious effect on the cells leading to a decrease in cell numbers but during the simulated dialysis period the cells adapted to the applied stresses. Over a 96-h period in the model both a clinical isolate and a skin isolate of S. epidermidis adopted a more hydrophobic phenotype. The data presented here show that the bacteria grown in this in-vivo reflective CAPD model continually adapt to their environment and become more tolerant to the stresses imposed. The adapted cells were seen to colonise silicone rubber substrata.
Effects on Walker 256 tumour of carmustine associated with a cholesterol-rich microemulsion (LDE)
Authors: Teixeira Raquel S , Curi Rui , Maranhão Raul C
Published: July 2004

A cholesterol-rich microemulsion that binds to low-density lipoprotein (LDL) receptors (LDE), after injection into the bloodstream, concentrates in neoplastic tissues that over-express those receptors. LDE can thus serve as a vehicle for drug targeting. It was shown that carmustine side effects are pronouncedly reduced when the drug is associated with LDE in cancer patients. In this study, the therapeutic action of LDE associated with carmustine was compared with that of the non-associated drug in rats implanted with Walker 256 tumour. The toxicity and anti-tumour activity in rats treated with either free carmustine or carmustine associated with LDE and in control rats treated with saline solution were determined after a single intraperitoneal injection. The LD90 (90% lethal dose) of LDE-carmustine was 77 mg kg−1 and of free carmustine was 44 mg kg−1, indicating that LDE decreases toxicity. LDE-carmustine was able to decrease tumour mass at a lower dose level than free carmustine. Tumour regression time was shorter in LDE-carmustine- than in free carmustine-treated animals. Therefore, this study shows that the association of carmustine with LDE increases the therapeutic index of carmustine.
Eudragit RL100 nanoparticle system for the ophthalmic delivery of cloricromene
Authors: Bucolo Claudio , Maltese Adriana , Maugeri Francesco , Busà Barbara , Puglisi Giovanni , Pignatello Rosario
Published: July 2004

A Eudragit RL100 polymer nanoparticle system loaded with cloricromene was prepared and characterized on the basis of physicochemical properties, stability and drug release features. To investigate the ocular bioavailability of cloricromene after inclusion in the polymer matrix, the new nanoparticle system was topically administered in the rabbit eye and compared with an aqueous solution of the same drug. The nanoparticle system showed interesting size distribution and surface charge values, suitable for ophthalmic application. The results indicated that the dispersion of cloricromene within Eudragit RL100 polymer nanoparticles increased its ocular bioavailability and enhanced the biopharmaceutical profile. The new cloricromene-loaded nanoparticle system described here may be useful in clinical practice.
Determination of the effective path of contact of undercut involute gear teeth
Authors: Pedrero J I , Artés M , García-Masiá C
Published: July 2004

An approximate equation for accurate determination of the inner point of the involute profile of undercut spur and helical gear teeth is presented. This point may have influence on the effective path of contact and consequently on the contact ratio, the length of the path of contact and the stress levels, which should be taken into account for calculation and standardization purposes. Since the equation is valid for any tool proportions, it is very efficient for computer applications.
A parametric study of a blown powder laser cladding and alloying process using a two-dimensional conduction model
Authors: Kumar S , Roy S
Published: July 2004

A two-dimensional model has been developed to predict the temperature field and melt pool shape during blown powder laser cladding. A finite volume method has been used to solve the two-dimensional energy equation for a body moving relative to a stationary laser heat source. A boundary fitted coordinate system has been employed as the built-up surface geometry is complex. Important dimensionless groups representing laser parameters power ( P) and scanning speed ( U) and the process parameters built-up height and average dilution are identified. The effect of laser parameters on process parameters is investigated. For cladding P/U should always be kept low (less than 1) to reduce the average dilution, and in order to achieve the desired clad height the power level P should be controlled.
Study on improvements of the five-point double-toggle mould clamping mechanism
Authors: Lin W Y , Hsiao K M
Published: July 2004

In current designs of the conventional and Fanuc five-point double-toggle mechanisms, the lengths of moving-platen side links are greater than the lengths of tailstock-platen side links in order to provide enough horizontal space for the ejector unit and to avoid the unsound transmission characteristic. In this study, another method to provide such a space is adopted. From a parametric study, the method can be proved practicable and the individual profiles of toggle linkages for the two types of mechanism with the characteristics of time saving or a larger opening stroke and/or thrust saving can be found. Moreover, objective comparisons of the performances between the two types of mechanism are also given.
The effect of a crack-tip radius on the validity of the singular solution
Authors: Dini D , Hills D A
Published: July 2004

The influence of the finite crack-root radius on the local stress field at the root of a crack is found explicitly. This is then applied as an inner asymptotic solution, embedded with the conventional crack-tip singular solution, to quantify the possible influence of local rounding on the ability of the singular solution to capture the characteristics of the crack-tip process zone. The scaling factor employed is the conventional crack-tip stress intensity, and the example of a simple edge crack in a tension field is used to illustrate the method.
An Incremental K-means algorithm
Authors: Pham D T , Dimov S S , Nguyen C D
Published: July 2004

Data clustering is an important data exploration technique with many applications in engineering, including parts family formation in group technology and segmentation in image processing. One of the most popular data clustering methods is K-means clustering because of its simplicity and computational efficiency. The main problem with this clustering method is its tendency to coverge at a local minimum. In this paper, the cause of this problem is explained and an existing solution involving a cluster centre jumping operation is examined. The jumping technique alleviates the problem with local minima by enabling cluster centres to move in such a radical way as to reduce the overall cluster distortion. However, the method is very sensitive to errors in estimating distortion. A clustering scheme that is also based on distortion reduction through cluster centre movement but is not so sensitive to inaccuracies in distortion estimation is proposed in this paper. The scheme, which is an incremental version of the K-means algorithm, involves adding cluster centres one by one as clusters are being formed. The paper presents test results to demonstrate the efficacy of the proposed algorithm.
Equations of motion with the identity mass matrix for holonomic systems
Authors: Herman P
Published: July 2004

Some consequences concerning holonomic systems described in terms of the inertial quasi-velocities (IQV) are discussed in this note. Introducing the IQV vector into Lagrange's formulation leads to first-order equations with the identity mass matrix of the system. The first-order differential equations give an interesting insight into dynamics and some important properties. The two examples that are provided use the dynamical equations in terms of IQV.
Singularity robust inverse dynamics of planar 2-RPR parallel manipulators
Authors: Ider S Kemal
Published: July 2004

In planar parallel robots, limitations occur in the functional workspace because of interference of the legs with each other and because of drive singularities where the actuators lose control of the moving platform and the actuator forces grow without bounds. A 2-RPR (revolute, prismatic, revolute joints) planar parallel manipulator with two legs that minimizes the interference of the mechanical components is considered. Avoidance of the drive singularities is in general not desirable since it reduces the functional workspace. An inverse dynamics algorithm with singularity robustness is formulated allowing full utilization of the workspace. It is shown that if the trajectory is planned to satisfy certain conditions related to the consistency of the dynamic equations, the manipulator can pass through the drive singularities while the actuator forces remain stable. Furthermore, for finding the actuator forces in the vicinity of the singular positions a full rank modification of the dynamic equations is developed. A deployment motion is analysed to illustrate the proposed approach.
Effects of convection in laser-guided transportation
Authors: Chen L , Yan Y , Zhang R
Published: July 2004

Weak focusing laser beams can guide micrometre-sized beads to direct-write two-dimensional patterns or three-dimensional structures. Applications based on laser guidance have been found in many fields including biological research areas. This paper discusses the effects of convection, which is the main disturbance during laser-guided transportation. The heat generated by optical absorption causes the convection flow, as observed in experiments. To investigate this convection flow, a finite element analysis (FEA) model was set up and computation under different heat load conditions was carried out. The results show that the convection flow velocity at the laser beam centre has a direct proportional relation to the incident power and varies with the position of the laser beam.
Microstructure and mechanical properties of pure titanium models fabricated by selective laser melting
Authors: Santos E C , Osakada K , Shiomi M , Kitamura Y , Abe F
Published: July 2004

The pore structure, the hardness and the mechanical properties of three-dimensional titanium models formed by the selective laser melting method with a neodymium-doped yttrium aluminium garnet (Nd:YAG) pulsed laser are investigated. The optical and scanning electron micrographs show that pore structure depends on the peak power, the scan speed and the hatching pitch. The Vickers hardness of the laser formed specimens is around 240 HV (0.2 kgf), higher than that of the wrought material (125-160 HV). Depth profiling by X-ray photoelectron spectroscopy (XPS) indicates that oxygen pick-up occurs during laser forming of the titanium model processed in a closed chamber filled with argon. The fatigue strength of the titanium models formed by changing the hatching pitch and the laser power were measured. It is possible to improve the fatigue strength of the as-formed models by decreasing the hatching pitch or by hot isostatic pressing (HIP). The specimens after HIP have a fatigue strength comparable to the wrought material.
Maximizing the buckling loads of symmetrically laminated composite rectangular plates using a layerwise optimization approach
Authors: Narita Y , Turvey G J
Published: July 2004

Research on optimum lay-ups and buckling loads of laminated plates is briefly reviewed. A new sequential, iterative procedure, known as layerwise optimization (LO), for determining the optimum lay-ups and maximum buckling loads of symmetrically laminated rectangular plates is described. The physical basis of the procedure is explained. LO is shown to be highly efficient, with reductions in computational effort of more than 99 per cent being possible in comparison to some simultaneous optimization procedures. Three examples are presented of the use of the LO procedure to determine the optimum lay-ups and associated maximum buckling loads of 8- and 24-layer symmetrically laminated rectangular plates subjected to uniform, uniaxial and biaxial compression. For 18 combinations of free, simply supported and clamped edge conditions, it is shown that the LO procedure generally leads to the optimum solution. In the very few instances where a local rather than a global solution was obtained, the maximum buckling load was only 4–6.5 per cent lower than the optimum value.
Droplet size and velocity distributions in a spray from a pressure swirl atomizer: Application of maximum entropy formalism
Authors: Mondal D , Datta A , Sarkar A
Published: July 2004

The present work has attempted a unification of the empirical spray parameters for the pressure swirl atomizers with the maximum entropy formalism principle for the predictions of both size and velocity distributions in a spray. The information entropy is maximized under suitable constraint conditions to evaluate a number-based droplet size and velocity joint distribution parameter. The constraint equations have been defined to include the spray parameters, such as the Sauter mean diameter, spray cone angle and liquid film thickness, to consider their influence on the distribution. A comparison of the predicted results using the present theory is made with the experimental data available in the literature and good agreement is achieved. The effects of the atomizer input conditions, such as injection pressure, ambient pressure and the properties of atomizing liquids, on the size and velocity distributions are studied using the present model. A calculation of the efficiency of the atomization process using the size and velocity distribution functions is also made to study the effect of operating conditions on the performance of atomization.
A shielded hot-wire probe to detect flow reversals with one-dimensional pulsating flow
Authors: Benjamin S F , Liu Z , Roberts C A
Published: July 2004

A shielded hot-wire probe, based on the patent of Neuerburg, was further developed to detect flow reversals in a one-dimensional pulsating flow regime for frequencies of 66 and 100 Hz. This single-sensor hot wire, partially surrounded by a tubular shield with an oblique tip, has successfully detected the intermittent flow reversals caused by the flow interruption device in a pulsating air flow rig. For the purpose of reverse flow detection, this shielded single-sensor hot-wire probe provides a cost effective and simple-to-use alternative to multisensor hot-wire probes and optical velocity measurement devices such as laser Doppler anemometry.
Plasma deposition of constrained layer damping coatings
Authors: Rongong J A , Goruppa A A , Buravalla V R , Tomlinson G R , Jones F R
Published: July 2004

Plasma techniques are used to generate constrained layer damping (CLD) coatings on metallic substrates. The process involves the deposition of relatively thick, hard ceramic layers on to soft polymeric damping materials while maintaining the integrity of both layers. Reactive plasma sputter-deposition from an aluminium alloy target is used to deposit alumina layers, with Young's modulus in the range 77–220GPa and thickness up to 335 μ, on top of a silicone film. This methodology is also used to deposit a 40μ alumina layer on a conventional viscoelastic damping film to produce an integral damping coating. Plasma CLD systems are shown to give at least 50 per cent more damping than equivalent metal-foil-based treatments. Numerical methods for rapid prediction of the performance of such coatings are discussed and validated by comparison with experimental results.
Decommissioning of a liquid effluent treatment R&D facility
Authors: Hamblin C , Ensor B
Published: July 2004

The United Kingdom Atomic Energy Authority (UKAEA) is responsible for managing the decommissioning of the nuclear reactors and other radioactive facilities used for the UKAEA nuclear research and development programme in a safe and environmentally responsible manner with the objective of restoring the sites for conventional use. It is also responsible for input to the European fusion research programme and for maximizing the income from the land and buildings at its sites at Dounreay in Scotland, Windscale in Cumbria, Harwell and Culham in Oxfordshire and Winfrith in Dorset. Building 336.28 typified the problems encountered during the removal of redundant facilities from the liquid effluent treatment plant at Harwell. The building was constructed in the late 1940s, was lined with asbestos limpet and contained a range of poorly characterized liabilities that had been ‘mothballed’ after use. Decommissioning was carried out following competitive tender. The work involved the removal of radioactive liquids and wastes, the dismantling and removal of contaminated tanks, vessels, glove boxes and test rigs and the demolition of the building. There were uncertainties associated with the radioactive inventory, the extent of the contamination beneath the floor slab and the processing requirements for the waste ion-exchange resins. These were addressed by a combination of characterization surveys (carried out by UKAEA at the pre-tender stage) and the use of unit work rates within the contract for some activities. In addition, the flexible approach by both the client (UKAEA) and the implementation contractor (NNC Limited) enabled the project end-point to be redefined to manage the widespread low-level contamination discovered beneath the floor slab.
Experimental investigation of the energy efficiency of gas commercial laundry dryers
Authors: Williamson N , Bansal P K
Published: July 2004

In this paper the energy efficiency of commercial laundry dryers is investigated. Previous studies have found that a small energy saving can be found in household tumbler dryers, but there has been no investigation of larger commercial gas-fired tumbler dryers. Two relatively new gas-fired dryers have been tested in an in situ commercial setting in Auckland. One of the dryers incorporated an energy efficiency measure that allowed it to recirculate the exhaust air directly back into the drum. Both the dryers were found to be very energy intensive but to remove moisture at very high rates. The recirculation was found to decrease both the energy efficiency and the moisture removal rate of the dryer.
Shakedown behaviour of thick cylindrical vessels with crossholes
Authors: Makulsawatudom P , Mackenzie D , Hamilton R
Published: July 2004

A finite element investigation of the shakedown behaviour of thick cylindrical pressure vessels with crossholes subject to cycling internal pressure is presented. Radial and offset crossholes with circular and elliptical cross-sections are considered, with three types of intersection between the crosshole and main bore: plain, chamfered and blended. The results show that the crosshole significantly alters the shakedown behaviour of thick cylindrical vessels. The limit pressure is relatively unaffected, but the shakedown pressure decreases significantly. This increases the possibility of cyclic plasticity failure mechanisms in thick cylinders for à wider range of cylinder geometries. The form of the intersection between the crosshole and main bore does not significantly affect the shakedown behaviour.
Using aerodynamic methods for the testing of hydraulic machines
Authors: Zaher M A
Published: July 2004

The present paper attempts to give a broad review of tests performed with air as a cheaper and more accurate option when compared with tests using incompressible flows. The work presents a description of an aerodynamic test- bench for examining models of hydraulic machines. Experimental and theoretical values of local velocity and density were determined at several axial planes. Test results were also used to show how water machine models can be equally tested in air tunnels. Analysis is supported by the theory of dynamic similarity. The work presents a qualitative and quantitative description of actual cases based on model tests. With special emphasis on conditions of similarity, which have a fundamental significance in the design of hydraulic machines, the author explains the possibility of supplementing them by using air as the working medium. The influence of Reynolds number, roughness and turbulence is also discussed.
Dynamic analysis of shaker mixers and an asymmetrical twin-container design
Authors: Fan D , Wakeman R J
Published: July 2004

The container of a shaker mixer follows a complicated movement. The movement of the mixer is described using six coordinates. Important parameters such as the relative angles and the angular speeds of the main parts of the mixer in the movement are calculated. Expressions for the centroid positions of the main parts of the mixer and the centroid velocity components of the container in the static reference coordinates are given. Using a dynamic analysis of the shaker mixer, the method for calculating the power required for an asymmetrical twin-container shaker mixer is described. An energy-saving design of an asymmetrical twin-container shaker mixer is presented.
Neural network modelling and prediction in multipass steel processing
Authors: Fraser A W , Martin E B , Morris A J
Published: July 2004

Operations comprising a sequence of single passes whereby relative motion occurs between a workpiece and a shaping tool on each pass is termed a multipass process. This paper describes the development of a neural network modelling approach for the representation of the complex dynamic interactions that are characteristic of multipass processes. The developments are then applied to a world-scale steel beam rolling mill for the prediction of motor torque and rolling force. Two neural network structures were designed to satisfy different operational requirements. The first was to provide online single pass ahead predictions, while the second was for off-line multipass ahead predictions. Although the results obtained using the ‘best’ single network model were promising, significant prediction improvements were achieved by combining (stacking) multiple neural networks that were trained using different network topologies.
An approach to evaluate the service life of rubber springs used in rail vehicle suspensions
Authors: Luo R K , Wu W X , Cook P W , Mortel W J
Published: July 2004

The stress-endurance (S-N) method has been widely used in metal fatigue in the railway industry over many years. However, when this method is applied to rubber-like materials, it seems not as successful as when it is applied to metallic materials. Recently, an integrated fatigue evaluation programme has been carried out with the aim of improving the design of anti vibration components in response to the increasing demands of the rail operating environment. This programme will also make simulations more reliable and relevant to industrial applications, especially for the fatigue design of rubber springs used in rail vehicle suspensions. The continuum mechanics (total life) approach has been used to characterize the fatigue life in terms of the cyclic stress range (S-N curve). It is suggested that the effective stress, at, can be used as a parameter (taking three principal stress ranges into consideration) to evaluate fatigue failure. The initial verification of this approach has been carried out on two types of rubber spring. The results have shown good agreement between the fatigue test of the components and the simulation based on this approach.
A thermal analysis of a new railway brake concept using liquid cooling
Authors: Cartigny F , Dufrénoy P , Desmet B
Published: July 2004

The aim of this study is to evaluate the performances of the energy dissipation of a new railway disc brake concept, intended for an urban exploitation. Because of the increase in the rates of trains and subways as well as the number of passengers, brakes have become increasingly a major safety component. In urban exploitation, these systems are subjected to multiple braking actions and have operational limits. A new concept based on a liquid-cooled system is suggested to decrease the energy storage in the disc. A numerical model of this new concept was realized and its performances were estimated by comparing temperature evolution at the friction interface with that obtained with the classical brake. The temperatures reached on a single stop with the cooled concept are higher than those of a classical brake. However, an important temperature decrease is observed at the end of braking so that, for successive brakings, the liquid-cooling principle causes an overall decrease in temperature. Moreover, the use of a material with a high thermal effusivity increases the part of the flow generated at the interface transmitted to the pad and thus reduces the surface temperature.
Quasi-static modelling of wheel-rail reactions due to crosswind effects for various types of high-speed rolling stock
Authors: Diedrichs B , Ekequist M , Stichel S , Tengstrand H
Published: July 2004

This work describes a quasi-static tool developed to assess the performance swiftly of crosswind stability for three types of rolling stock with conventional, semi-trailer and Jacobs bogie running gear configurations. The prediction accuracy of the results returned by the tool for the quasistatic assumption is fair in comparison with results of more advanced multibody simulation software that is commercially available. The codes, which are based on steady equilibrium equations for the wheels and axles, bogie frames and vehicle body/bodies, handle arbitrarily canted embankments and circular curves. To a large extent the accuracy hinges on the bodies' lateral displacements relative to the contact points between the wheels and rails; therefore proper modelling of the suspension systems and bump stops are found to be important. Examples are given of the limitations associated with the quasi-static approach, studying the following: (a) the combined wind and track scenario in Deutsche Bahn AG's guideline, (b) the effects of typical track irregularities for high-speed transportation as a function of train speed and (c) the effects of oscillating crosswind. It has also been found relevant to demonstrate some of the large differences regarding provisions regulating crosswind safety. To this extent the present results are compared with those derived with the British Group Standard and also with results presented in the guideline of Deutsche Bahn AG. In addition, examples are given of the differences found of the permissible crosswind speed using calculated (with CFD-RANS) and experimentally obtained aerodynamic loads.