bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Rubus yellow net virus as a distinct badnavirus and its detection by PCR in Rubus species and in aphids
Authors: JONES A TEIFION , McGAVIN WENDY J , GEERING A D W , LOCKHART B E L
Published: July 2006

Rubus yellow net virus (RYNV) infects Rubus species and cultivars worldwide and is an essential component of raspberry veinbanding mosaic (RVBMD), a virus disease complex that causes serious decline in plant vigour and productivity. The virus is transmitted, probably in a semi‐persistent manner, by the large raspberry aphid, Amphorophora idaei in Europe, and A. agathonica in North America. The particles of RYNV are bacilliform in shape and measure 80–150 × 25–30 nm, similar to those of badnaviruses. A1.7 kb fragment of the viral DNA was amplified by PCR and then directly sequenced. Analysis of this sequence suggests that RYNV is possibly a distinct species in the genus Badnavirus and is most closely related to Gooseberry vein banding associated virus (GVBAV) and Spiraea yellow leaf spot virus, two other badnaviruses described recently. Using the sequence derived from the PCR‐amplified viral DNA fragment, RYNV‐specific primers were designed and used in PCR to assay for RYNV in a range of Rubus germplasm infected with RYNV, with other unrelated viruses and virus‐like diseases found in Rubus, and in healthy plants. RYNV was detected in all glasshouse cultures of RYNV‐infected plants, whether alone or in complex infections with other viruses, but not from healthy Rubus plants, nor from plants infected with other viruses. It was also detected in field‐grown raspberry plants with and without symptoms of RVBMD and in raspberry plants infected with RYNV by viruliferous A. idaei. RYNV was also detected by PCR in A. idaei following access feeds on RYNV‐infected plants of 1 h or more. PCR failed to amplify DNA from gooseberry infected with GVBAV confirming the specificity of the RYNV analysis. PCR detection of RYNV in dormant raspberry buds allows assays to be made outside the natural growing season, providing a useful application for plant introduction and quarantine programmes.
Effect of strain‐specific hypersensitive resistance on spatial patterns of virus spread
Authors: THACKRAY D J , SMITH L J , CHENG Y , PERRY J N , JONES R A C
Published: July 2006

Spatial patterns of spread were compared between strains of Bean yellow mosaic virus (BYMV) that differ in causing systemic necrotic (hypersensitive) or non‐necrotic symptoms in narrow‐leafed lupin (Lupinus angustifolius). Both types of BYMV were spread naturally by aphids from adjacent infected pasture into a large lupin block (‘natural spread site’), or from clover plants introduced as virus sources into two field experiments with lupin. Cumulative spatial data for plants with disease symptoms from a range of times in the growing period were assessed using Spatial Analysis by Distance IndicEs (SADIE). At the‘natural spread site’, with non‐necrotic BYMV, the extent of clustering of plants with symptoms increased gradually over time, while with necrotic BYMV there was less clustering and no increase over time. In both experiments, for the type of BYMV that was introduced into a plot, there was a gradual increase in clustering, but with this being greater with non‐necrotic BYMV. In the second experiment, there was also significant clustering of plants with symptoms of non‐necrotic BYMV in plots without introduced non‐necrotic foci but not for necrotic BYMV in plots without introduced necrotic foci. When clustering data for plants with newly recorded symptoms was tested for spatial association between successive assessment dates, association was positive for both BYMV types though stronger for the non‐necrotic type, declining as the temporal lag increased. Generally, association was strongest for assessments 2–3 wk apart, corresponding approximately to the period for BYMV to move systemically in plants and for obvious symptoms to appear in shoot tips. Contour maps for local association between dates showed that the strongest spatial associations were from coincidence of infection gaps rather than infection patches. The combination of information from clustering and association analysis showed that spread of non‐necrotic BYMV is less diffuse, with considerably more localised infection surrounding the infection sources. This work demonstrates how spatial virus spread can be diminished when hypersensitive (necrotic) resistance is deployed, and the limitations associated with employing hypersensitivity that is strain specific.
Identification and application of RAPD markers for anthracnose resistance in water yam (Dioscorea alata)
Authors: MIGNOUNA H D , ABANG M M , ONASANYA A , ASIEDU R
Published: July 2006

Anthracnose, caused by Colletotrichum gloeosporioides, is the most severe foliar disease of water yam (Dioscorea alata) worldwide. The tetraploid breeding line, TDa 95/00328, is a source of dominant genetic resistance to the moderately virulent fast growing salmon (FGS) strain of C. gloeosporioides. Bulked segregant analysis was used to search for random amplified polymorphic DNA (RAPD) markers linked to anthracnose resistance in F1 progeny derived from a cross between TDa 95/00328 and the susceptible male parent, TDa 95–310. Two hundred and eighty decamer primers were screened using bulks obtained from pooled DNA of individuals comprising each extreme of the disease phenotype distribution. A single locus that contributes to anthracnose resistance in TDa 95/00328 was identified and tentatively named Dcg‐1. We found two RAPD markers closely linked in coupling phase with Dcg‐1, named OPI71700 and OPE6950, both of which were mapped on the same linkage group. OPI71700 appeared tightly linked to the Dcg‐1 locus; it was present in all the 58 resistant F1 individuals and absent in all but one of the 13 susceptible genotypes (genetic distance of 2.3 cM). OPE6950 was present in 56 of the 58 resistant progeny and only one susceptible F1 plant showed this marker (6.8 cM). Both markers successfully identified Dcg‐1 in resistant D. alata genotypes among 34 breeding lines, indicating their potential for use in marker‐assisted selection. OPI71700 and OPE6950 are the first DNA markers for yam anthracnose resistance. The use of molecular markers presents a valuable strategy for selection and pyramiding of anthracnose resistance genes in yam improvement.
Heat tolerance of strawberry tarsonemid mite Phytonemus pallidus
Authors: HELLQVIST SVEN
Published: July 2006

The heat tolerance of the strawberry tarsonemid mite Phytonemus pallidus ssp. fragariae was studied in northern Sweden by treating adult mites in hot water at temperatures 44°C, 46°C and 48°C. During the summer, the shortest exposure times required to kill all adult mites at these temperatures were 6, 2.5 and 1.25 min, respectively. It is concluded that hot‐water treatment of strawberry runners for 6.5 min at 46°C would suffice to kill all tarsonemid mites on infested runners. This exposure time includes the time needed to raise the temperature of the plant material to that of the water bath. In the autumn, from the middle of September and later, the mites became successively much more heat tolerant as they prepared for hibernation. It is expected that longer exposure periods are needed to kill mites on frigoplants.
Phenological growth stages of the persimmon tree (Diospyros kaki)
Authors: GARCÍA‐CARBONELL S , YAGÜE B , BLEIHOLDER H , HACK H , MEIER U , AGUSTÍ M
Published: July 2006

Detailed crop‐specific descriptions and codes are presented for the growth stages of the persimmon tree, contributing to the standardisation of national and international testing systems in fruit growing. Based on the general BBCH‐scale, the codes describe growth stages using a two‐digit numerical system and differentiate between principal and secondary growth stages to allow separation of developmental steps. Growth stages for bud, leaf and shoot development, inflorescence emergence, flowering, fruit development and fruit maturity are described. A feature of the system is that homologous stages of different crops are presented by the same codes.
Effects ofRuta graveolensleaves on soil characteristics and on seed germination and early seedling growth of four crop species
Authors: OLIVA A , LAHOZ E , CONTILLO R , ALIOTTA G
Published: July 2006

Effects of rue (Ruta graveolens) leaves on soil characteristics and on germination and seedling growth of four crop species (radish, zucchini, cauliflower and tomato) were investigated. Soil not previously associated with rue was mulched and amended with its fresh leaves. The objectives of the present study were to determine: (i) the changes in soil chemical characteristics after addition of rue leaves, (ii) the growth responses in soils treated with R. graveolens leaves, and (iii) whether the soil chemistry changes affect plant growth. Results indicate that soil incorporated with rue leaves had higher values of water‐soluble phenolics, electrical conductivity and nitrate, and lower pH values compared to untreated soil. Seed germination of radish and tomato was suppressed in covered and amended soils compared to control soil. Seedling development for all the species was suppressed in incorporated and amended soil, compared to the rue‐free soil. Correlations between soil chemical characteristics, germination and seedling growth of plants are also discussed.
LDL‐Apheresis Reduces P‐Selectin, CRP and Fibrinogen— Possible Important Implications for Improving Atherosclerosis
Authors: Kobayashi Shuzo , Oka Machiko , Moriya Hidekazkeu , Maesato Kyoko , Okamoto Koji , Ohtake Takayasu
Published: July 2006

Abstract:  Although it is known that LDL‐apheresis improves coronary artery stenosis (CAS) as well as ischemic limbs seen in patients with peripheral arterial occlusive disease (PAOD), the underlying mechanisms remain still unknown. LDL‐apheresis might exert its favorable action through anti‐inflammatory effects. We studied whether or not serum or plasma levels of P‐selectin, high sensitivity C‐reactive protein (hsCRP), monocyte chemotractant protein‐1 (MCP‐1) or fibrinogen could be reduced in patients with PAOD before and after 10 sessions of LDL‐apheresis. Sixteen patients (12 patients with hemodialysis, HD) with PAOD were enrolled in the present study. LDL‐apheresis was carried out 10 times (treated plasma of 3000 mL) over 5 weeks. Serum levels of P‐selectin were significantly reduced from 516 ± 153 to 290 ± 52 ng/mL before and after 10‐sessions of LDL‐apheresis, respectively (P < 0.05). Likewise, serum levels of hsCRP decreased from 9.118 ± 2.649 to 5.587 ± 2.445 mg/L (P < 0.01); and plasma fibrinogen levels statistically decreased from 196 ± 9.82 to 149 ± 7.97 mg/dL (P < 0.01), whereas serum levels of MCP‐1 were not significantly changed. The favorable actions of LDL‐apheresis might include anti‐inflammatory effects, which could lead to an improvement of CAS and PAOD. Moreover, this intervention might be applicable for patients with atherosclerotic cardiovascular disorders, particularly in patients with HD.
The Influences of Method of Calcium Correction and the Timing of Blood Collection on Application of The K/DOQI Clinical Practice Guidelines for Bone Metabolism and Disease in Japan
Authors: Yokoyama Keitaro , Katoh Naohiko , Kasai Kenji , Kubo Hitoshi , Murai Seizou , Shoji Ryo , Imamura Noritsugu , Saika Souichi , Yumita Sigeru , Ishida Mari , Takasu Shinji , Kono Takashi , Yoshida Yutaka , Wakabayashi Tsunemichi , Kimua Yasuo , Hosoya Tasuo
Published: July 2006

Abstract:  We investigated the treatment of renal osteodystrophy (ROD) in Japan and problems concerning the K/DOQI Guidelines. The subjects were 3698 hemodialysis patients (2328 males and 1370 females) with a mean age of 61.4 years. On average, they had been on hemodialysis for 8.34 years. The serum phosphorus level was <3.5 mg/dL in 5% of the subjects, 3.5–5.5 mg/dL in 49%, 5.6–7.0 mg/dL in 33%, and >7.0 mg/dL in 13%. The serum calcium level was <8.4 mg/dL in 16% of the subjects, 8.4–9.5 mg/dL in 47%, 9.5–10.2 mg/dL in 22%, and >10.2 mg/dL in 15%. The intact PTH level was <150 pg/mL in 57%, 150–300 pg/mL in 27%, and >300 pg/mL in 16% of the patients. The first problem is that correcting Ca is not always performed in clinical fields. The uncorrected calcium level was 9.14+/−0.92 mg/dL, while the corrected calcium level [Ca = Ca + 0.8 × (4‐Alb)] was 9.26+/−0.93 mg/dL (P < 0.05). The second problem is that the timing of blood collection is not described in the K/DOQI Guidelines. Subjects with a serum phosphorus level >7.0 mg/dL at 3 days after the previous dialysis were selected for assessment. In these patients, the midweek serum phosphorus level (7.13+/−0.15 mg/dL) at was significantly lower than that (8.11+/−0.15 mg/dL) at the beginning of the next week (P < 0.001). These results suggest that it is necessary to specify the timing of measurement and the method of Ca correction when guidelines for management of ROD are established in the future.
Direct Adsorption of Low‐Density Lipoprotein by DALI‐LDL‐Apheresis: Results of a Prospective Long‐term Multicenter Follow‐up Covering 12 291 Sessions
Authors: Bosch Thomas , Gahr Simon , Belschner Ulrike , Schaefer Claudia , Lennertz Andrea , Rammo Jörg ,   for the DALI Study Group
Published: July 2006

Abstract:  Direct adsorption of lipoproteins (DALI) is the first low density lipoprotein (LDL)‐apheresis technology by which atherogenic LDL and lipoprotein(a) (Lp(a)) can be selectively removed from whole blood without plasma separation. The present follow‐up was carried out to evaluate the clinical efficacy, selectivity and safety of long‐term DALI apheresis. The follow‐up was carried out in an open, prospective uncontrolled multicenter clinical design. Included were 158 drug‐resistant hypercholesterolemic patients from 28 apheresis centers. These patients underwent 12 291 DALI sessions between January 1997 and March 2002. The patients suffered from severe atherosclerosis and their mean LDL‐C was 188 mg/dL before the sessions. Mean follow‐up was 25 ± 16 (range 1–56) months during which 78 ± 53 sessions were carried out. In most treatments, DALI 750 (63%) or DALI 1000 (30%) adsorbers were used. On average, 7423 ± 1495 mL blood was processed at a flow rate of 84 ± 16 mL/min in 102 ± 25 min. Acute reductions by the single DALI sessions averaged 69 ± 12% for LDL‐C, 41 ± 18% for TG, 15 ± 10% for HDL‐C, 19 ± 11% for fibrinogen and 62 ± 24% for Lp(a) (in patients with Lp(a) > 30 mg/dL). Adverse events were recorded in only 3.9% of the sessions. In this 5‐year follow‐up, long‐term therapy with DALI was safe, effective and selective as LDL‐C and Lp(a) could be reduced by >60% per session in approximately 100 min treatment time while HDL‐C decrease and the incidence of AE were low.
Preparation of Low Density Lipoprotein from Large Apheresis Cartridges for Induction of Cell Death in Saos2 Osteoblasts
Authors: Klein Benjamin Y , Kerem Zohar , Rojansky Nathan
Published: July 2006

Abstract:  Atherosclerosis is epidemiologically associated with postmenopausal osteoporosis presumably by common etiologic factors, reflecting a state of comorbidity in aging. Osteoblasts make a significant facet of this comorbidity state. The present study shows that LDL (native and oxidized) separated by conventional density ultracentrifugation induces osteoblast cell growth arrest in culture. Since the density unltracentrifugation is a tedious procedure we examined, in the present study, the option of LDL purification by ionic strength elution from LDL‐apheresis cartridges. We tested the ability of LDL and oxidized LDL (oxLDL) from apheresis columns to induce apoptosis in human Saos2 osteoblasts. Isotonic NaCl effluent washed from LDL‐apheresis columns (before starting elution of LDL) induced cell proliferation. In some of the effluent fractions that stimulated Saos2 osteoblasts, up to 15% of the stimulation levels could be significantly inhibited with antilipoprotein A antibodies. After the isotonic washing (150 mM NaCl), upon elution with high ionic strength, 0.2–0.3 M NaCl, some front‐runner LDL eluate fractions also induced cell growth and others did not inhibit Saos2 cell growth. This indicates that these fractions might have been contaminated with apolipoprotein A or with other mitogenic compounds. In contrast, the late‐to‐elute (last 1/3) LDL portion, with a mean density of 1.042 g/mL, killed the cells as expected. This suggests that only the very last one third of LDL eluted by high ionic strength (0.3–0.5 M) is free of osteoblast‐mitogenic compounds or lipoprotein‐A containing particles. This approach to LDL purification might serve as a convenient and economic method for studying the composition of individual LDL particles and their interaction with cells in culture.
Patterns of Platelet Response in Idiopathic TTP/HUS: Frequency of Declining Platelet Counts With Plasma Exchange and the Recognition and Significance of a Pseudo Refractory State
Authors: Hay Shauna N , Egan Jennifer A , Millward Peter A , Bandarenko Nicholas , Brecher Mark E
Published: July 2006

Abstract:  For thrombotic thrombocytopenic purpura (TTP), daily plasma exchange (TPE) is typically discontinued when the platelet count normalizes (>150 × 109/L). We observed a decline in platelet count during TPE and in patients who appeared pseudo‐refractory because of a platelet count plateau (100–150 109/L range). In the present study, we evaluated platelet count trends in TTP patients. Retrospective review of TTP patients from 01/1999 to 12/2004 was completed. Patients were categorized based on platelet count trends: Group I, counts rose then decreased to levels <100 × 109/L; Group II, counts declined following TPE initiation; Group III, counts rose continuously; Group IV, counts decreased after the count was >100 × 109/L. Additionally, we identified pseudo‐refractory patients caused by a platelet count plateau (>100 × 109/L but <150 × 109/L). We identified 60 TTP patients. Within Group I (17 patients/17 series/19.1% of total), the mean decrease in platelet count was 67.3% ± 22.1% following initial rise. Within Group II (24 patients/25 series/28.1% of total), the mean decrease was 28% ± 5.3% following presentation. Group III included 31 patients/39 series (43.8% of the total). Within Group IV (seven patients/eight series/9.0% of total), the mean decrease was 17.4% ± 12.6% following a sustained rise >100 × 109/L. With a declining platelet count and daily TPE, it is generally sufficient to stay the course and the decline will reverse. Our limited experience with pseudo‐refractory patients supports discontinuing TPE when counts plateau between 100 and 150 × 109/L when a therapy goal is a platelet count of 150 × 109/L. Recognition of this pseudo‐refractory state can minimize the risks of prolonged TPE and the risks of adjunct interventions.
Polyamines as an Inhibitor on Erythropoiesis of Hemodialysis Patients by In Vitro Bioassay Using the Fetal Mouse Liver Assay
Authors: Yoshida Katsunori , Yoneda Tatsuo , Kimura Syouki , Fujimoto Kiyohide , Okajima Eigoro , Hirao Yoshihiko
Published: July 2006

Abstract:  The pathogenesis of anemia in patients with chronic renal failure has been greatly attributed to erythropoietin (EPO) deficiency. Recently, however, there has been some thought that uremic inhibitors might suppress the activity of EPO and reduce the maturation of erythropoiesis. Polyamines are well known to be involved in the regulation of cellular proliferation and differentiation. Furthermore, the polyamine levels in the serum or erythrocytes are elevated in chronic hemodialysis patients, and can be lowered immediately by hemodialysis. In the present study, we first measured the polyamines levels (putrescine, spermidine, spermine) by high performance liquid chromatography (HPLC) in 20 chronic hemodialysis patients, and investigated the effects of polyamines on erythropoiesis by in vitro bioassay using fetal mouse liver cells. The direct effects of polyamines in erythroid colony formation in the medium with and without EPO were evaluated. Each polyamine level in chronic hemodialysis patients was higher than in the healthy subjects, and a significant negative correlation was found between polyamines and erythropoiesis. Polyamines inhibited the activity of EPO, but they did not have any direct effect on colony formation of the fetal mouse liver cells. These results suggest that polyamines have inhibitory effects on the proliferation or maturation of erythroid precursor cells and are intimately involved in the pathogenesis of renal anemia in chronic hemodialysis patients.
A Case Report of Progressive Multifocal Leukoencephalopathy in a Human T‐Cell Lymphotropic Virus Type 1‐Infected Hemodialytic Patient
Authors: Matsuda Hiroto , Hayashi Koichi , Meguro Mariko , Saruta Takao
Published: July 2006

Abstract:  We experienced a case manifesting progressive multifocal leukoencephalopathy (PML) in a hemodialytic patient with hepatitis C virus‐induced liver cirrhosis and human T‐cell lymphotropic virus type‐1 (HTLV‐1)‐associated uveitis. A 57‐year‐old male patient had received chronic hemodialysis therapy for 10 years, during which he received multiple blood transfusions and HTLV‐1‐associated uveitis developed. He complained of visual disturbance and disorientation. Brain CT scan showed diffuse and multifocal low density areas in occipital and temporal lobes, with gray matter relatively spared. MRI imaging showed high intensity lesions in the same areas. Cerebrospinal fluid culture was negative, but using nested PCR, rearranged regulatory region of JC virus DNA was detected. His consciousness level gradually deteriorated and complete paraplegia developed. Seven months after admission, he died of pneumonia. An autopsy confirmed the diagnosis of PML. Notably, mononuclear cell infiltration, gliosis and demyelinating lesions but no nuclear inclusion bodies were observed in the thoracic cord, which suggested HTLV‐1‐associated myelopathy. Because JC virus is activated under immunocompromised conditions, precipitating factors in this case appear multifactorial; depressed immune system induced by chronic hemodialysis as well as blood‐borne hepatitis C virus/HTLV‐1 infection might contribute to the activation of dormant JC virus and the development of florid clinical manifestation of PML.
The Dose of Nafamostat Mesilate During Plasma Exchange With Continuous Hemodiafiltration in the Series‐Parallel Circuit
Authors: Nakae Hajime , Igarashi Toshiko , Tajimi Kimitaka
Published: July 2006

Abstract:  We studied nafamostat mesilate (NM) and interleukin (IL)‐18 levels to determine whether the dose of NM is reduced during plasma exchange (PE) with continuous hemodiafiltration (CHDF) when the series‐parallel circuit is used. The subjects of the current study included four patients with acute hepatic failure who underwent PE with CHDF. The four patients underwent a total 15 PE + CHDF procedures, and for each procedure, they were randomized to receive either a half‐dose of NM or no NM in the CHDF circuit. Eight procedures were carried out with NM administration, and seven were carried out without NM administration. The dose of NM in the NM group was significantly higher than that in the non‐NM group (P = 0.040). No significant differences were observed between the two groups in the inlet NM concentration, the outlet NM concentration, or the rate of IL‐18 removal. No statistical correlation was observed between the IL‐18 level and the NM dose, the inlet NM concentration, or the outlet NM concentration. There was no blood access difficulty such as catheter failure or clotting of the filter. Thus, it might be possible to carry out PE and CHDF with the series‐parallel method without administration of NM in the CHDF circuit.
Circulating Osteoprotegerin Affects Bone Metabolism in Dialysis Patients With Mild Secondary Hyperparathyroidism
Authors: Kazama Junichiro James , Omori Kentaro , Yamamoto Suguru , Ito Yumi , Maruyama Hiroki , Narita Ichiei , Gejyo Fumitake , Iwasaki Yoshiko , Fukagawa Masafumi
Published: July 2006

Abstract: Osteoprotegerin (OPG) is a soluble glycoprotein which inhibits osteoclastic formation and activity. Circulating OPG levels are elevated in uremia. The role of elevated circulating OPG levels in uremia remains unknown. Blood samples were obtained from 22 non‐diabetic dialysis patients who underwent iliac bone biopsy examination. The serum OPG concentration was assayed by ELISA. The circulating OPG levels showed a negative correlation with the ratio of eroded surface/bone surface (ES/BS) in biopsied iliac bone samples among 15 of those with plasma intact PTH levels less than 300 pg/mL (P < 0.05,r2 = 0.270). Patients with serum OPG levels less than 2.0 ng/mL showed significantly greater ES/BS values than those with levels ≥3.0 ng/mL, while the intact PTH levels were comparable among those groups. These tendencies disappeared when seven patients with plasma intact PTH levels more than 300 pg/mL were included into the analysis. In conclusion, circulating OPG levels showed a significant negative correlation with a bone resorption parameters in dialysis patients with mild secondary hyperparathyroidism. Circulating OPG might have a suppressive effect on osteoclastic bone resorption in dialysis patients.
Centrifugal Leukocytapheresis Therapy for Ulcerative Colitis Without Concurrent Corticosteroid Administration
Authors: Okada Hiroyuki , Takenaka Ryuta , Hiraoka Sakiko , Makidono Chiho , Hori Shin‐ichiro , Kato Jun , Okazaki Hiroaki , Kawamoto Hirofumi , Mizuno Motowo , Shiratori Yasushi
Published: July 2006

Abstract:  Corticosteroid administration is an important therapy for active ulcerative colitis. However, long‐term corticosteroid use is associated with serious complications such as osteoporosis, diabetes, and growth retardation. The effect of combination therapy corticosteroid plus leukocytapheresis has been previously reported, but that of leukocytapheresis with no corticosteroid is unknown. We carried out a preliminary study of six patients (two men and four women) with active ulcerative colitis (severe in two, moderately severe in four) who did not respond to 5‐aminosalicylate derivatives, but refused corticosteroid use. Centrifugal leukocytapheresis was carried out once per week totaling four sessions per course. Treatment was considered effective when patients experienced clinical remission, which was defined as a frequency of diarrhea of four times or less and absence of visible blood in the stool, after one course. Leukocytapheresis was effective in five of six patients(83%). With cases stratified by severity, both severe cases and three of four moderately severe cases showed effectiveness. Clinical activity scores according to Lichtiger et al. in cases where leukocytapheresis was effective decreased from 9.8 to 6.6 at 1 week (P < 0.0001), declining further 2.4 at the end of the course. No obvious complications of leukocytapheresis were noted except for a decrease in hemoglobin by 1 g/dL. Centrifugal leukocytapheresis without corticosteroid treatment can induce remission in patients with active ulcerative colitis, and might be particularly beneficial for patients in whom adverse effects preclude the use of corticosteroids.
Use of Picard and Newton Iteration for Solving Nonlinear Ground Water Flow Equations
Authors: Mehl Steffen
Published: July 2006

This study examines the use of Picard and Newton iteration to solve the nonlinear, saturated ground water flow equation. Here, a simple three‐node problem is used to demonstrate the convergence difficulties that can arise when solving the nonlinear, saturated ground water flow equation in both homogeneous and heterogeneous systems with and without nonlinear boundary conditions. For these cases, the characteristic types of convergence patterns are examined. Viewing these convergence patterns as orbits of an attractor in a dynamical system provides further insight. It is shown that the nonlinearity that arises from nonlinear head‐dependent boundary conditions can cause more convergence difficulties than the nonlinearity that arises from flow in an unconfined aquifer. Furthermore, the effects of damping on both convergence and convergence rate are investigated. It is shown that no single strategy is effective for all problems and how understanding pitfalls and merits of several methods can be helpful in overcoming convergence difficulties. Results show that Picard iterations can be a simple and effective method for the solution of nonlinear, saturated ground water flow problems.
Nonlinear Energy Sink With Uncertain Parameters
Authors: Gourdon E. , Lamarque C. H.
Published: July 2006

The effects of a nonlinear energy sink during the instationary regime are analyzed by introducing uncertain parameters to verify the robustness of the transient spatial energy transfer when parameters are not well known. It was shown that it is possible to passively absorb energy from a linear nonconservative system (damped) structure to a nonlinear attachment weakly coupled to the linear one. This rapid and irreversible transfer of energy, named energy pumping, is studied by taking into account uncertainties on parameters, especially damping (since damping plays a great role and there is a lack of knowledge about it). In essence, the nonlinear subsystem acts as a passive nonlinear energy sink for impulsively applied external vibrational disturbances. The aim is to be able to apply energy pumping in practice where the nonlinear attachment realization will never perfectly reflect the design. Since strong nonlinearities are involved, polynomial chaos expansions are used to obtain information about random displacements. Not only are numerical investigations done, but nonlinear normal modes and the role of damping are also analytically studied, which confirms the numerical studies and shows the supplementary information obtained compared to a parametrical study.
Nonlinear Response and Suppression of Chaos by Weak Harmonic Perturbation Inside a Triple Well Φ6-Rayleigh Oscillator Combined to Parametric Excitations
Authors: Siewe Siewe M. , Moukam Kakmeni F. M. , Tchawoua C. , Woafo P.
Published: July 2006

The nonlinear response and suppression of chaos by weak harmonic perturbation inside a triple well Φ6-Rayleigh oscillator combined to parametric excitations is studied in this paper. The main attention is focused on the dynamical properties of local bifurcations as well as global bifurcations including homoclinic and heteroclinic bifurcations. The original oscillator is transformed to averaged equations using the method of harmonic balance to obtain periodic solutions. The response curves show the saddle-node bifurcation and the multi-stability phenomena. Based on the Melnikov’s method, horseshoe chaos is found and its control is made by introducing an external periodic perturbation.
Lobes and Lenses in the Stability Chart of Interrupted Turning
Authors: Szalai Róbert , Stépán Gábor
Published: July 2006

In this paper, a new method for the stability analysis of interrupted turning processes is introduced. The approach is based on the construction of a characteristic function whose complex roots determine the stability of the system. By using the argument principle, the number of roots causing instability can be counted, and thus, an exact stability chart can be drawn. In the special case of period doubling bifurcation, the corresponding multiplier −1 is substituted into the characteristic function, leading to an implicit formula for the stability boundaries. Further investigations show that all the period doubling boundaries are closed curves, except the first lobe at the highest cutting speeds. Together with the stability boundaries of Neimark-Sacker (or secondary Hopf) bifurcations, the unstable parameter domains are formed from the union of lobes and lenses.
Subharmonic-Response Computation and Stability Analysis for a Nonlinear Oscillator Using a Split-Frequency Harmonic Balance Method
Authors: Dunne J. F.
Published: July 2006

A split-frequency harmonic balance method (SF-HBM) is developed to obtain subharmonic responses of a nonlinear single-degree-of-freedom oscillator driven by periodic excitation. This method is capable of generating highly accurate periodic solutions involving a large number of solution harmonics. Responses at the excitation period, or corresponding multiples (such as period 2 and period 3), can be readily obtained with this method, either in isolation or as combinations. To achieve this, the oscillator equation error is first expressed in terms of two Mickens functions, where the assumed Fourier series solution is split into two groups, nominally associated with low-frequency or high-frequency harmonics. The number of low-frequency harmonics remains small compared to the number of high-frequency harmonics. By exploiting a convergence property of the equation-error functions, accurate low-frequency harmonics can be obtained in a new iterative scheme using a conventional harmonic balance method, in a separate step from obtaining the high-frequency harmonics. The algebraic equations (needed in the HBM part of the method) are generated wholly numerically via a fast Fourier transform, using a discrete-time formulation to include inexpansible nonlinearities. A nonlinear forced-response stability analysis is adapted for use with solutions obtained with this SF-HBM. Period-3 subharmonic responses are obtained for an oscillator with power-law nonlinear stiffness. The paper shows that for this type of oscillator, two qualitatively different period-3 subharmonic response branches can be obtained across a broad frequency range. Stability analysis reveals, however, that for an increasingly stiff model, neither of these subharmonic branches are stable.
A Practical Approach for the Linearization of the Constrained Multibody Dynamics Equations
Authors: Negrut Dan , Ortiz Jose L.
Published: July 2006

The paper presents an approach to linearize the set of index 3 nonlinear differential algebraic equations that govern the dynamics of constrained mechanical systems. The proposed method handles heterogeneous systems that might contain flexible bodies, friction, control elements (user-defined differential equations), and nonholonomic constraints. Analytically equivalent to a state-space formulation of the system dynamics in Lagrangian coordinates, the proposed method augments the governing equations and then computes a set of sensitivities that provide the linearization of interest. The attributes associated with the method are the ability to handle large heterogeneous systems, ability to linearize the system in terms of arbitrary user-defined coordinates, and straightforward implementation. The proposed approach has been released in the 2005 version of the MSC.ADAMS/Solver(C++) and compares favorably with a reference method previously available. The approach was also validated against MSC.NASTRAN and experimental results.
Buckling Analysis of Multiwalled Carbon Nanotubes Under Torsional Load Coupling With Temperature Change
Authors: Yao Xiaohu , Han Qiang
Published: July 2006

The buckling of multiwalled carbon nanotubes under torsional load coupling with temperature change is researched. The effects of torsional load, temperature change, surrounding elastic medium, and van der Waals forces between the inner and outer nanotubes are taken into account at the same time. Using continuum mechanics, an elastic multishell model with thermal effect is presented for buckling of a multiwalled carbon nanotube embedded in an elastic matrix under thermal environment and torsional load. Based on the model, numerical results for the general case are obtained for the thermal effect on buckling of a multiwalled carbon nanotube under torsional load. It is shown that the buckling torque of a multiwalled carbon nanotube under a certain value of temperature change is dependent on the wave number of torsional buckling modes, and a conclusion is drawn that at room or lower temperature the critical torsional load for infinitesimal buckling of a multiwalled carbon nanotube increases as the value of temperature change increases, while at temperature higher than room temperature the critical torsional load for infinitesimal buckling of a multiwalled carbon nanotube decreases as the value of temperature change increases.
Effects of CO2 Laser Surface Processing on Fracture Behavior of Silicon Nitride Ceramic
Authors: Sun Li , Malshe Ajay P. , Jiang Wenping , McCluskey Philip H.
Published: July 2006

Surface defects generated by grinding deteriorate the flexural strength of the silicon nitride (Si3N4) ceramic. In this paper, CO2 laser surface processing was applied to eliminate the grinding-induced defects. SEM micrograph showed that the surface integrity of Si3N4 samples was improved after laser processing. Four-point bending tests and fractographic analysis indicated that the flexural strength and fracture origins were affected by the change of surface integrity in laser-treated Si3N4 samples. The effect of grinding-induced residual stress on flexural strength of laser-treated samples was discussed. It was concluded that laser surface processing had significant effects on fracture behavior of flexure Si3N4 samples.
Theoretical and Experimental Studies for the Application of Shape Memory Alloys in Civil Engineering
Authors: Dolce Mauro , Cardone Donatello
Published: July 2006

Shape memory alloys (SMAs) have great potential for use in the field of civil engineering. The authors of this paper have been involved, from 1996, in several experimental and theoretical studies of the application of SMAs in civil engineering, for national and international research projects. This paper provides an overview of the main results achieved, consisting of the conceptual design, implementation, and testing of three families of SMA-based devices, namely: (i) special braces for framed structures, (ii) seismic isolation devices for buildings and bridges, and (iii) smart ties for arches and vaults. The main advantage of using SMA-based devices in the seismic protection of structures comes from the double-flag shape of their hysteresis loops, which implies three favorable features, i.e., self-centering capability, good energy dissipation capability, and high stiffness at small displacements. The main advantage of smart ties comes from the thermal behavior of SMA superelastic wires, which is opposite to that of steel rod. This implies a strong reduction of the force changes caused by variations of air temperature.
Seismic Vibration Control Using Superelastic Shape Memory Alloys
Authors: McCormick Jason , DesRoches Reginald , Fugazza Davide , Auricchio Ferdinando
Published: July 2006

Superelastic NiTi shape memory alloy (SMA) wires and bars are studied to determine their damping and recentering capability for applications in the structural control of buildings subjected to earthquake loadings. These studies improve the knowledge base in regard to the use of SMAs in seismic design and retrofit of structures. The results show that the damping properties of austenitic SMAs are generally low. However, the residual strain obtained after loading to 6% strain is typically <0.75%. In general, it is shown that large diameters bars perform as well as wire specimens used in non-civil-engineering applications. The results of a small-scale shake table test are then presented as a proof of concept study of a SMA cross-bracing system. These results are verified through analytical nonlinear time history analysis. Finally, a three-story steel frame implementing either a traditional steel buckling-allowed bracing system or a SMA bracing system is analyzed analytically to determine if there is an advantage to using a SMA bracing system. The results show that the SMA braces improve the response of the braced frames.
Effect of H-Doping on Damping Capacity of Various NiTi-Based Alloys at kHz Frequencies
Authors: Coluzzi B. , Biscarini A. , Mazzolai G. , Mazzolai F. M. , Tuissi A.
Published: July 2006

The internal friction Q−1 and the Young’s modulus E of NiTi based alloys have been measured as a function of temperature after various thermomechanical and hydrogen-doping treatments given to the materials. Hydrogen is found to play a major role introducing tall damping peaks associated with Snoek-type and H-twin boundary relaxations. Levels of Q−1 as high as 0.08 have been detected, which are among the highest to date measured in metal alloy systems. For appropriate alloy compositions, these peaks occur at around room temperature (for acoustical frequencies), thus providing a good opportunity to reduce machinery vibrations and noise pollution. In the paper, the conditions are highlighted under which maximum efficiency can be reached in the conversion of mechanical energy into heat.
A Phenomenological Model for Superelastic NiTi Wires Based on Plasticity With Focus on Strain-Rate Dependency Caused by Temperature
Authors: Schmidt Ina
Published: July 2006

A simple one-dimensional model has been developed to illustrate methods to account for transformation bands in plasticity-based models. Austenite-martensite and martensite-austenite transformations are described by two transformation surfaces in analogy to yield surfaces in plasticity theory. The strain-rate dependence of the material behavior is caused solely by the latent heat of the transformations. Optical and thermographical experiments have been carried out to clarify the dependence of the transformation bands on the distribution of latent heat and therefore on the thermomechanical behavior.
Crystal Plasticity Based Fe Model for Understanding Microstructural Effects on Creep and Dwell Fatigue in Ti-6242
Authors: Venkataramani Gayathri , Deka Dhyanjyoti , Ghosh Somnath
Published: July 2006

This paper is aimed at identifying key microstructural parameters that play important roles in the failure initiation of polycrystalline Ti-6242 subjected to creep and dwell loading. A finite element model, incorporating rate dependent elastocrystal plasticity, is developed for analyzing evolving variables in material microstructure. The crystal plasticity parameters are characterized by a combination of microtesting, orientation imaging microscopy, computational simulations, and minimization process involving Genetic algorithms (Ga). Accurate phase volume fractions and orientation distributions that are statistically equivalent to those observed in orientation imaging microscope scans are incorporated in the computational model of polycrystalline Ti-6242 for constant strain rate, creep, and dwell tests. The computational model is used for the identification of possible microstructural variables that may result in local crack initiation. Basal normal stress, equivalent plastic strain, and stress in loading direction are considered as candidate parameters, of which the former is chosen as most probable from results of creep and dwell experiments and simulations. Creep induced load shedding phenomena is observed to lead to high value stresses that cause failure. The role of grain orientation with respect to the loading axis and misorientation with its neighbors, in causing load shedding and stress localizations is explored.
Micromechanical Modeling of Particulate Composites for Damping of Acoustic Waves
Authors: Haberman Michael R. , Berthelot Yves H. , Cherkaoui Mohammed
Published: July 2006

The self-consistent (SC) micromechanical model of a composite containing coated micro-inclusions, originally proposed in the static regime by Cherkaoui et al. (1994, J. Eng. Mater. Technol., 116, 274–278), is implemented in the quasistatic regime by the introduction of frequency dependent complex moduli for the matrix material. The original model is improved by using dilute strain concentration tensor (DSCT) formulation. It is shown that these concentration tensors can be used to approximate effective composite behavior of composites containing ellipsoidal inclusions having a known orientation distribution or of composites containing multiple types of coated inclusions. The DSCT formulation is also shown to be capable of modeling the effects of multiple scales (submicron-meso-macro), as well as that of a distribution of inclusion coating thicknesses. Various potential material modeling applications are verified through comparison with experimental data in the literature. Notably, the DSCT SC model is applied in the quasistatic regime for calculation of acoustic transmission loss of a slab of viscoelastic composite submerged in water for the range of frequencies between 0-100kHz and compared with experimental data of Baird et al. (1999, J. Acoust. Soc. Am., 105, 1527–1538).
An Approximated Harmonic Balance Method for Nonlinear Vibration of
Viscoelastic Structures
Authors: Boutyour El Hassan , Daya El Mostafa , Azrar Lahcen , Potier-Ferry Michel
Published: July 2006

In this paper, we deal with the nonlinear vibration of viscoelastic shell structures. Coupling an approximated harmonic balance method with one mode Galerkin’s procedure, one obtains an amplitude equation depending on two complex coefficients. The latter are determined by solving a classical eigenvalue problem and two linear ones. To show the applicability and the validity of our approach, the amplitude-frequency and the amplitude loss factor relationships are illustrated for a sandwich plate with a viscoelastic central layer and a viscoelastic circular ring.
Stress-Strain-Temperature Behavior Due to B2-R-B19′ Transformation in NiTi Polycrystals
Authors: Šittner P. , Novák V. , Lukáš P. , Landa M.
Published: July 2006

Thermomechanical behavior of superelastic NiTi wires undergoing sequential B2-R-B19′ martensitic transformation was investigated by two recently developed in-situ experimental methods (in-situ neutron diffraction and combined ultrasonic and electric resistance measurements) capable of detecting and recognizing the activity of various deformation/transformation processes in NiTi and theoretically by micromechanical modeling. An earlier model of SMA polycrystal transformation is further developed, so it accounts for the strains due to the R-phase related deformation processes in activated NiTi. A continuous variation of the rhombohedral distortion angle α of the R-phase structure with temperature and stress is newly introduced as a legitimate deformation mechanism. Simulation results for NiTi bars and wires exposed to three types of thermomechanical tests—mechanical loading at constant temperature, cooling under constant stress, and recovery stress tests are presented and confronted with results.
Shape Memory Alloys Cyclic Behavior: Experimental Study and
Modeling
Authors: Malécot P. , Lexcellent C. , Foltête E. , Collet M.
Published: July 2006

Shape memory alloys (SMA) are good candidates for being integrated in composite laminates where they can be used as passive dampers, strain sensors, stiffness or shape drivers. In order to improve the SMA modeling and develop the use of these alloys in structural vibration control, better understandings of cyclic behavior and thermal dissipation are needed. The present study investigates experimentally the cyclic behavior of SMA and more particularly, the influence of strain rates on three different materials. The thermal dissipation aspect is also studied using an infrared camera. A phenomenological model based on the RL model (Raniecki, B., Lexcellent, C., 1994, “RL Models of Pseudoelasticity and Their Specification for Shape Memory Solids.” Eur. J. A/Solids, 13, pp. 21–50) is then presented with the intention of modeling the behavior’s alterations due to the cycling. By introducing the thermodynamic first principle, a study of the heat equation is developed in order to predict the temperature evolution during a cyclic tensile test. Furthermore, in order to model the damping effect created by the hysteresis phenomenon and the stiffness variation due to the phase transformation, an equivalent nonlinear complex Young’s modulus is introduced. This notion usually used for viscoelastic materials is adapted here to SMA. Moreover, the impact of cycling on the equivalent modulus is presented. As a conclusion, a numerical results panel obtained with the phenomenological cyclic SMA model, the heat equation, and the equivalent complex Young modulus is presented.