bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of di-(2-ethylhexyl) phthalate on steroidogenesis by the ovarian granulosa cells of immature female rats
Authors: Svechnikova I , Svechnikov K , Söder O
Published: August 2007

Phthalate esters are known to exert harmful effects on mammalian reproduction and fertility, but their potential adverse effects on the hormonal functions of the ovary have not yet been elucidated in detail. Here, we investigated the effects of di-(2-ethylhexyl) phthalate (DEHP) on the hypothalamic–pituitary–gonadal axis of young developing female rats, as well as on ex vivo steroidogenesis by granulosa cells (GCs) and secretion of LH by gonadotropes. Exposure of 20-day-old female rats to 500 mg DEHP by oral gavage once daily for 10 days reduced their serum levels of progesterone and estradiol, while tending to enhance levels of LH. Furthermore, primary cultures of GCs isolated from these rats exhibited an attenuated capacity to produce progesterone in response to stimulation by LH and FSH, as well as a lower degree of transport of endogenous cholesterol into mitochondria. Moreover, the abilityof primary cultures of pituitary cells isolated from DEHP-treated rats to produce and secrete LH in response to GnRH was significantly enhanced. In addition, 2-ethylhexanoic acid, a metabolite of DEHP, significantly potentiated GnRH-stimulated production of LH by cultures of pituitary cells isolated from untreated 20-day-old female rats. Together, these data indicate that DEHP exerts dual effects on the pituitary–gonadal axis, stimulating the hormonal function of the pituitary and, at the same time, by inhibiting steroidogenesis by GCs.
Cell and molecular biology of Notch
Authors: Fiúza Ulla-Maj , Arias Alfonso Martinez
Published: August 2007

Notch signalling is a cell–cell communication process, which allows the establishment of patterns of gene expression and differentiation, regulates binary cell fate choice and the maintenance of stem cell populations. So far, the data published has elucidated the main players in the Notch signalling pathway. However, its regulatory mechanisms are exhibiting an increasing complexity which could account for the multitude of roles it has during development and in adult organisms. In this review, we will describe the multiple roles of Notch and how various factors can regulate Notch signalling.
Compressive behaviour of short-fibre-reinforced concrete
Authors: Ghosh S. , Bhattacharjya S. , Chakraborty S.
Published: August 2007

The most important parameters studied in the analysis of steel-fibre-reinforced composite (SFRC) are the tensile and flexural strength since these parameters dictate the composite behaviour. SFRC under compression has received less attention and most of the works are empirical and case-specific. However, compressive strength plays an important role in the complete understanding of composite behaviour. The current paper presents a comprehensive approach to predict the compressive behaviour of SFRC considering the possibility of fibre buckling in the matrix. The analytical development is based on the micro-mechanical behaviour describing the phenomenon in terms of fibre–matrix constitutive properties, their interface and proportioning. The development is based on single fibre stress–strain relationships, which is subsequently implemented into a composite model. The results of the analytical model are supplemented with those of experimental investigations and the results of the existing model in literature. The stress–strain behaviours capture the trend quite satisfactorily and are in good conformity with the results of experimental investigation and the existing model.
Adding steel fibres to improve shock vibration resistance of concrete
Authors: Kwan A. K. H. , Ng I. Y. T.
Published: August 2007

A newly developed shock vibration test method was employed to study the effects of shock vibration on steel-fibre-reinforced concrete so as to explore the possibility of improving the shock vibration resistance of concrete. In total, 21 batches of concrete with steel fibre contents ranging from 0 to 4% were cast and subjected to the shock vibration test at ages of 12 h, 1 day and 7 days. The results revealed that the effectiveness of adding steel fibres to alleviate the short-term damage caused by shock vibration (in terms of immediate reduction in ultrasonic pulse velocity) was quite low, especially for shock vibration applied at an early age. However, the effectiveness of adding steel fibres to mitigate the long-term damage caused by shock vibration (in terms of reduction in 28-day direct tensile strength) turned out to be much higher for shock vibration applied at age within 1 day than at later age. One probable reason is that, even after vibration damage had been caused, the continuing development of the steel–concrete bond while the concrete was still young could restore part of the reduced tensile strength. Finally, a new set of shock vibration control limits for steel fibre reinforced concrete was established.
Gingival Blood Flow in Periodontitis Patients Before and After Periodontal Surgery Assessed in Smokers and Non‐Smokers
Authors: Mavropoulos Antonios , Brodin Pål , Rösing Cassiano Kuchenbecker , Aass Anne Merete , Aars Harald
Published: August 2007

Background: The aim of this study was to evaluate the gingival blood flow of smokers and non‐smokers with periodontal disease before and after surgical periodontal treatment.

Methods: Nine smokers and six non‐smokers with at least two periodontal lesions were included in the study. Laser Doppler flowmetry was used to measure blood flow in two gingival sites and two skin sites. Two intrabony defects were treated surgically at the same time; enamel matrix derivative was applied at random to one of the sites, whereas the other site received a placebo gel. We measured resting gingival blood flow (GBF) and responses to cold pressor test (CPT) and to smoking and made continuous measurements of blood pressure (BP). Resting GBF levels of 26 young healthy subjects were used as a reference value.

Results: Resting GBF was significantly lower for the periodontitis patients compared to the reference subjects, regardless of smoking habits. GBF and gingival vascular conductance (VC) decreased significantly pre‐ and postoperatively in response to smoking. CPT evoked significant decreases in VC in smokers and non‐smokers. Skin blood flow decreased significantly in response to CPT, more so in the non‐smokers. BP was significantly higher in the non‐smokers.

Conclusions: Resting GBF of periodontitis patients was not lower in smokers than in non‐smokers, but it was significantly lower than in the younger reference subjects. In contrast to our earlier findings in healthy subjects, smoking one cigarette may cause a decrease in GBF and VC in periodontitis patients. These observations suggested the existence of a dysfunction in the gingival vasculature in smokers and non‐smokers with periodontitis.
Combined Therapy in a Patient With Papillon‐Lefèvre Syndrome: A 13‐Year Follow‐Up
Authors: Toygar Hilal Uslu , Kircelli Cem , Firat Ezgi , Guzeldemir Esra
Published: August 2007

Background: Papillon‐Lefèvre syndrome (PLS) is an autosomal recessive disease characterized by hyperkeratosis of the palms and soles combined with premature loss of the primary and permanent dentition. Several treatment regimens have been recommended in the literature; however, a definitive treatment protocol has not been established. This case report evaluates the success of combined therapy in managing a patient with PLS.

Methods: A 6‐year‐old girl diagnosed with PLS presented with aggressive periodontal destruction of her primary and permanent dentitions. After extraction of periodontally affected teeth, the edentate region was rehabilitated with different temporary dentures until her skeletal growth was complete. At the same time, her orthodontic treatment was performed. The early loss of her incisors resulted in inadequate alveolar bone height and width for esthetic‐advanced prosthetic rehabilitation. Alveolar bone augmentation was performed, and 6 months later, two intraosseous dental implants were placed into the central incisor zone.

Results: After 13 years of treatment and follow‐up, the patient had periodontally healthy permanent dentition. She had practiced meticulous oral hygiene, and the orthodontic treatment was successful and without incident. Alveolar ridge augmentation and placement of an intraosseous implant with guided bone regeneration were performed successfully.

Conclusions: This case report demonstrates that individually developed treatment protocols can provide long‐term dental/periodontal success in patients with PLS. A multidisciplinary approach with advanced periodontal surgery, orthodontic and prosthetic treatment, and implant therapy may be an appropriate treatment modality for dental rehabilitation in patients with PLS.
Gingival Crevicular Fluid VEGF Levels in Periodontal Health and Disease
Authors: Prapulla Devi V. , Sujatha Pai B. , Pradeep A.R.
Published: August 2007

Background: Vascular endothelial growth factor (VEGF), a glycoprotein, has attracted attention as a potential inducer of angiogenesis. It is detectable in periodontal tissues within endothelial cells, plasma cells, and macrophages and in junctional, sulcular, and gingival epithelium. In periodontitis patients, the volume of gingival crevicular fluid (GCF) and the total amount of VEGF collected from diseased sites were greater than from clinically healthy sites. The aim of the present study was to investigate the role of VEGF in periodontal disease progression and to investigate the effect of periodontal therapy on VEGF concentrations in GCF.

Methods: Forty‐five subjects were divided into three groups based on gingival index, clinical attachment loss, and radiographic evidence of alveolar bone loss: healthy (group 1), gingivitis (group 2), and chronic periodontitis (group 3). A fourth group consisted of subjects from group 3, 8 weeks after treatment (scaling and root planing). GCF samples collected from each patient were quantified for VEGF levels using enzyme‐linked immunosorbent assay. Further, the correlation between VEGF levels in situ and the clinical parameters was analyzed in all groups and was analyzed before and after treatment in the periodontitis group.

Results: The highest mean VEGF concentration (99.375 pg/ml) was observed in group 3, and the lowest was observed in group 1 (42.025 pg/ml). Its mean level in group 3 decreased to 54.60 pg/ml after treatment (group 4). Further, GCF VEGF levels showed a positive correlation with all of the clinical parameters.

Conclusions: VEGF levels in GCF increased from health to periodontitis, and periodontal treatment resulted in a reduction in their concentrations. These data indicated that VEGF plays a key role in periodontal disease progression and can be considered a biomarker of periodontal disease progression.
Analysis of the Potential Association of Implant Stability, Laboratory, and Image‐Based Measures Used to Assess Osteotomy Sites: Early Versus Delayed Loading
Authors: Tözüm Tolga F. , Turkyilmaz Ilser , Yamalik Nermin , Karabulut Erdem , Eratalay Kenan
Published: August 2007

Background: During the assessments made at presurgical, surgical, and follow‐up phases, the clinician may benefit from a wide array of clinical and/or image‐based measures. Because analysis of the potential associations among the various measures could improve the evaluation process for dental implants, this study attempted to determine the potential correlations among peri‐implant sulcus fluid (PISF) volume, implant stability, nitric oxide content of PISF, and marginal bone loss.

Methods: Seventeen completely edentulous patients seeking prosthetic rehabilitation were included. Two ball attachment mandibular overdentures were given to all patients, and early‐ (N = 18) and delayed‐loaded (N = 16) dental implants were compared during 24‐weeks of follow‐up. Resonance frequency analysis (RFA), marginal bone level, and PISF samples were taken for all dental implants.

Results: A consistent and negative correlation was observed between RFA measurements and marginal bone level, whereas some correlations also existed between RFA and PISF volume. The pattern of loading seemed to affect the relationship between RFA measurements and marginal bone level and, to a limited extent, the association between PISF volume and nitrite levels.

Conclusions: Where the potential associations among various implant‐related measures are concerned, the factors that may affect such associations (e.g., healing and loading) need to be considered. Data arising from the analysis of the associations between the wide arrays of available implant‐related measures may improve dental practitioners' assessment concerning endosseous dental implants.
A Hyperactive Neutrophil Phenotype in Patients With Refractory Periodontitis
Authors: Johnstone Andrea M. , Koh Adeline , Goldberg Michael B. , Glogauer Michael
Published: August 2007

Background: Neutrophils (PMNs) are critical components of the innate immune system and help to maintain oral health in the face of a constant bacterial challenge. However, along with protecting the periodontium from microbial invasion, these cells release potent lysosomal enzymes and oxygen radicals that can be destructive to periodontal tissues and lead to tooth loss. We examined neutrophil function in a unique population of patients diagnosed with refractory aggressive periodontitis (RAP).

Methods: Venous blood was obtained from 12 non‐smoking patients who had been diagnosed with RAP, 10 patients with chronic periodontitis who had responded to periodontal therapy (CP), and 13 periodontally healthy controls (HCs). Peripheral blood PMNs were loaded with dihydrorhodamine 123 and stimulated with phorbol 12‐myristate 13‐acetate (PMA) to measure the receptor‐independent respiratory burst of these key immune cells. Phagocytosis via the complement and Fc‐gamma receptors was also assessed.

Results: PMNs from patients with RAP displayed significantly increased PMA‐induced oxygen radical production compared to those from the HC and CP patients. PMNs from RAP patients also displayed increased phagocytosis compared to those from the CP group.

Conclusions: Our findings demonstrated a larger receptor‐independent respiratory burst and higher phagocytotic activity in PMNs derived from patients with RAP compared to PMNs derived from CP patients and periodontally HCs. We speculate that the higher intrinsic intracellular activity of the nicotinamide adenine dinucleotide phosphate oxidase system may account for the continued periodontal breakdown, despite ongoing periodontal therapy in these challenging patients.
The Impact of a Low‐Frequency Chlorhexidine Rinsing Schedule on the Subgingival Microbiota (the TEETH clinical trial)
Authors: Persson G. Rutger , Yeates Justin , Persson Rigmor E. , Hirschi‐Imfeld Regula , Weibel Marianne , Kiyak H. Asuman
Published: August 2007

Background: Information on the efficacy of chlorhexidine (CHX) rinsing on the subgingival microbiota is limited. This study tested if intermittent CHX rinsing over 5 years had an impact on the subgingival microbiota.

Methods: Subgingival plaque samples were analyzed by the checkerboard DNA‐DNA hybridization method in a double‐blind randomized CHX rinse study.

Results: A total of 210 subjects were included. The mean age of the subjects was 71.7 (± 4.1) years, and 56.2% were women. Evidence of alveolar bone loss was found in 39% of subjects. Bacterial loads were not correlated significantly with probing depth. At year 5, subjects in the CHX rinse group with no evidence of bone loss presented with lower total bacterial counts than control subjects with no bone loss. The levels of the following bacteria were significantly lower in the CHX group: Lactobacillus acidophilus (P <0.05), Eikenella corrodens (P <0.05), Fusobacterium nucleatum sp. nucleatum (P <0.01), Treponema denticola (P <0.05), Leptotrichia buccalis (P <0.05), and Eubacterium saburreum (P <0.05). No differences in bacterial loads were found between CHX and control rinse subjects with alveolar bone loss.

Conclusions: Older subjects with or without periodontitis carry a large variety of bacteria associated with periodontitis. Intermittent rinsing with CHX may provide a preventive benefit in reducing levels of bacteria but only in subjects without alveolar bone loss.
Nativity and Duration of Time in the United States: Differences in Fruit and Vegetable Intake Among Low-Income Postpartum Women
Authors: Dubowitz Tamara , Smith-Warner Stephanie A. , Acevedo-Garcia Dolores , Subramanian S.V. , Peterson Karen E.
Published: August 2007

Limited research has examined the association of diet with immigrant status, adjusting for multiple socio-demographic and contextual influences. Among 662 WIC-eligible postpartum women, those who were foreign-born and had lived in the United States for 4 or fewer years consumed 2.5 more fruit and vegetable servings daily than native-born women; this difference diminished with longer US residence. White women consumed 1 serving less than Latinas, and those speaking both English and Spanish at home consumed 1.4 servings more than English-only speakers after adjusting for other covariates.
Factors Related to HIV Disclosure in 2 South African Communities
Authors: Norman Amy , Chopra Mickey , Kadiyala Suneetha
Published: August 2007

Disclosure of HIV status is an essential part of behavior modification and access and adherence to treatment in people infected with HIV.

We conducted interviews in 2 South African communities of similar ethnic mix but with very different rates of disclosure of HIV status and found that disclosure was the catalyst for access to a variety of important and often essential resources. In the community with high rates of disclosure of HIV infection, disclosure led to greater access to formal institutional support and opportunities to take positive leadership roles in the community.

Our findings highlight the prominence of wider sociopolitical contexts for disclosure decisionmaking and the need for HIV interventions to increase levels of disclosure of HIV infection.
Trimming Exposure Data, Putting Radiation Workers at Risk: Improving Disclosure and Consent Through a National Radiation Dose-Registry
Authors: Shrader-Frechette Kristin
Published: August 2007

In the United States, regulatory standards allow workers to be exposed to ionizing radiation that can cause 1 additional cancer fatality per 400 workers per year. Because radiation-dose limits cover only single sources (e.g., a nuclear plant) or exposure classes (workplace, medical, or public) and are defined for average occupational exposure, workers typically do not know their precise cumulative, individual, and relative risks from radiation. Nevertheless, this information is necessary for informed consent, because most scientists say radiation effects are cumulative and linear with no risk threshold. To promote public health, informed consent, and better understanding of the effects of low-dose radiation, I argue for a multistage National Radiation-Dose Registry, beginning with cumulative, individual worker doses.
Prevalence and Correlates of Substance Use Among High School Students in South Africa and the United States
Authors: Reddy Priscilla , Resnicow Kenneth , Omardien Riyadh , Kambaran Nilen
Published: August 2007

Objectives. We compared prevalence rates and correlates of substance use among high school students in South Africa and the United States.

Methods. We used weighted data from 2 nationally representative surveys of high school students. We conducted bivariate and multivariate analyses and examined between-country differences in rates and correlates of substance use were examined.

Results. Rates of past-month alcohol and marijuana use were lower among South African students than among US students, but rates of illicit hard drug use were higher. Correlates of use in the 2 countries differed. For example, female gender was protective against tobacco, alcohol, and marijuana use in South Africa, whereas in the United States it was protective only against marijuana use. Black race/ethnicity was associated with lower rates of past-month cigarette and alcohol use in both countries, but the protective effect for alcohol use was stronger in South Africa.

Conclusions. Crosscultural studies can elucidate common and culturally unique pathways to drug use. Our results can inform future research, policies, and behavioral interventions in South Africa.
The Effect of Disseminating Evidence-Based Interventions That Promote Physical Activity to Health Departments
Authors: Brownson Ross C. , Ballew Paula , Brown Kathrin L. , Elliott Michael B. , Haire-Joshu Debra , Heath Gregory W. , Kreuter Matthew W.
Published: August 2007

Objectives. We explored the effect of disseminating evidence-based guidelines that promote physical activity on US health department organizational practices in the United States.

Methods. We implemented a quasi-experimental design to examine changes in the dissemination of suggested guidelines to promote physical activity (The Guide to Community Preventive Services) in 8 study states; the remaining states and the Virgin Islands served as the comparison group. Guidelines were disseminated through workshops, ongoing technical assistance, and the distribution of an instructional CD-ROM. The main evaluation tool was a pre- and postdissemination survey administered to state and local health department staffs (baseline n=154; follow-up n=124).

Results. After guidelines were disseminated through workshops, knowledge of and skill in 11 intervention-related characteristics increased from baseline to follow-up. Awareness-related characteristics tended to increase more among local respondents than among state participants. Intervention adoption and implementation showed a pattern of increase among state practitioners but findings were mixed among local respondents.

Conclusions. Our exploratory study provides several dissemination approaches that should be considered by practitioners as they seek to promote physical activity in the populations they serve.
Assessment of a Medical Outreach Program to Improve Access to HIV Care Among Marginalized Individuals
Authors: Cunningham Chinazo O. , Sanchez John Paul , Heller Daliah I. , Sohler Nancy L.
Published: August 2007

Marginalized populations are disproportionately affected by HIV, yet they have poor access to health services. Outreach programs focus on improving access, but few are evaluated. We assessed a medical outreach program targeting unstably housed, HIV-infected individuals. We extracted data from 2003–2005 to examine whether keeping medical appointments was associated with patient and program characteristics.

Patients kept appointments more frequently when they were walk-in or same-day appointments (compared with future appointments; adjusted odds ratio [AOR]=1.69; 95% confidence interval [CI] = 1.38, 2.08), when they were at a community-based organization’s drop-in center (compared with single-room occupancy hotels; AOR=2.50; 95% CI=1.54, 4.17), or when made by nonmedical providers (compared with medical providers; future appointments: AOR = 1.38; 95% CI = 1.05, 1.80; same-day appointments: AOR = 1.70; 95% CI = 1.03, 2.81).

These findings demonstrate the importance of program-related characteristics in health services delivery to marginalized populations.
The Treatment of Smoking by US Physicians During Ambulatory Visits: 1994–2003
Authors: Thorndike Anne N. , Regan Susan , Rigotti Nancy A.
Published: August 2007

Objectives. We sought to determine whether US physicians’ practice patterns in treating tobacco use at ambulatory visits improved over the past decade with the appearance of national clinical practice guidelines, new smoking cessation medications, and public reporting of physician performance in counseling smokers.

Methods. We compared data from the National Ambulatory Medical Care Survey, an annual survey of a random sample of office visits to US physicians, between 1994–1996 and 2001–2003.

Results. Physicians identified patients’ smoking status at 68% of visits in 2001–2003 versus 65% in 1994–1996 (adjusted odds ratio [AOR]=1.16; 95% confidence interval [CI]=1.04, 1.30). Physicians counseled about smoking at 20% of smokers’ visits in 2001–2003 versus 22% in 1994–1996 (AOR=0.84; 95% CI=0.71, 0.99). In both time periods, smoking cessation medication use was low (<2% of smokers’ visits) and visits with counseling for smoking were longer than those without such counseling (P<.005).

Conclusions. In the past decade, there has been a small increase in physicians’ rates of patients’ smoking status identification and a small decrease in rates of counseling smokers. This lack of progress may reflect barriers in the US health care environment, including limited physician time to provide counseling.
Intersections of Ethnicity and Social Class in Provider Advice Regarding Reproductive Health
Authors: Downing Roberta A. , LaVeist Thomas A. , Bullock Heather E.
Published: August 2007

Objectives. We examined how ethnicity and social class influence women’s perceptions of reproductive health care. Of primary interest was assessing whether health care providers are perceived as advising low-income women, particularly women of color, to limit their childbearing and to what extent they feel they are discouraged by providers from having future children.

Methods. Ethnically diverse, low-income (n=193) and middle-class women (n=146) completed a questionnaire about their pregnancy-related health care experiences.

Results. Logistic regression analyses revealed that low-income women of color experienced greater odds of being advised to limit their childbearing than did middle-class White women. A separate model demonstrated that low-income Latinas reported greater odds of being discouraged from having children than did middle-class White women.

Conclusions. Low-income women of color were more likely to report being advised to limit their childbearing and were more likely to describe being discouraged from having children than were middle-class White women. More research is needed regarding how ethnicity and social class impact women’s experiences with reproductive health care.
Widening Ethnic Disparities in Infant Mortality in Southern Brazil: Comparison of 3 Birth Cohorts
Authors: Matijasevich Alicia , Victora Cesar G. , Barros Aluísio J.D. , Santos Iná S. , Marco Paula L. , Albernaz Elaine P. , Barros Fernando C.
Published: August 2007

Objectives. We analyzed trends in mortality among infants born to White and to Black or mixed-race women in 3 population-based cohorts representing all births in 1982, 1993, and 2004 in Pelotas, southern Brazil.

Methods. Births were assessed during daily visits to all maternity hospitals. Maternal skin color was classified by the interviewers as White or Black or multi-racial. We used logistic regression to adjust for socioeconomic, demographic, and health services variables.

Results. The mortality rate among infants born to White mothers declined from 30.4 per 1000 live births in 1982 to 13.9 per 1000 in 2004, compared with 53.8 per 1000 to 30.4 per 1000 among those born to Black and mixed-race mothers. Differences for neonatal mortality were even more marked, with reductions of 47% and 11% for infants born to White and Black or mixed-race women, respectively. Adjusted analyses showed that ethnic group differences in neonatal and infant mortality were partly explained by differences in poverty and prenatal care.

Conclusions. Over a 22-year period, improvements in health indicators were greater for infants born to White women than for other infants. The widening racial gap requires special attention from policymakers.
Dampness and Mold in the Home and Depression: An Examination of Mold-Related Illness and Perceived Control of One’s Home as Possible Depression Pathways
Authors: Shenassa Edmond D. , Daskalakis Constantine , Liebhaber Allison , Braubach Matthias , Brown MaryJean
Published: August 2007

Objectives. We evaluated a previously reported association between residence in a damp and moldy dwelling and the risk of depression and investigated whether depression was mediated by perception of control over one’s home or mold-related physical illness.

Methods. We used survey data from 8 European cities. A dampness and mold score was created from resident- and inspector-reported data. Depression was assessed using a validated index of depressive symptoms.

Results. Dampness or mold in the home was associated with depression (odds ratio [OR]=1.39, 1.44, and 1.34, for minimal, moderate, and extensive exposure, respectively, compared with no exposure). This association became attenuated when perception of control (OR=1.34, 1.40, and 1.24; global P=.069) or a physical health index (OR = 1.32, 1.37, and 1.15; global P= .104) was included in the model. The mediation effects of perception of control over one’s home and by physical health appeared to be additive.

Conclusions. Dampness and mold were associated with depression, independent of individual and housing characteristics. This association was independently mediated by perception of control over one’s home and by physical health.
Computational Model to Investigate the Sound Radiation from Rolling Tires
Authors: Biermann Jan , von Estorff Otto , Petersen Steffen , Schmidt Holger
Published: August 2007

Tire/road noise is one of the most urgent problems in traffic noise abatement. Therefore, to facilitate the design process of low noise tire/road systems, the development of appropriate computational tools, accounting for the most relevant effects of the noise generation and radiation, seems essential. However, until now no physically based and validated models exist that can be used to determine the sound radiation of rolling vehicle tires within the relevant frequency range and with reasonable accuracy. The numerical model presented here is based on a simulation process that may be split into several analysis steps: computation of the nonlinear stationary rolling process, analysis of the tire dynamics caused by the road roughness, and computation of the sound radiation. This contribution is concerned with the latter part of the analysis procedure.

For the sound radiation analysis, the vibrations on the tire surface are extracted from a preceding structural analysis and used as boundary conditions in the acoustic model. The acoustic simulation process is based on the finite/infinite element approach, where an improved variant of the so-called Astley-Leis elements is used to model the sound radiation. The efficiency of the employed numerical methods is somewhat essential, because computational costs generally restrict the frequency range which can be simulated. By evaluating the sound pressure field, it is possible to compare the acoustic performance of specific tire/road systems, and the influence of certain parameters, such as the road texture or the impedance, on the noise radiation can be studied. The current work focuses on the validation of the computational model. Hence, characteristic results from the numerical simulations are compared with corresponding measurement data obtained from different test setups, including standing as well as rolling tires.

This paper is dedicated to Em. O. Univ. Professor Dipl.-Ing. Dr. Techn. Dr. H. C. Franz Ziegler on the occasion of his 70th birthday.
Struktur, Verhalten und Einstellung von Schweizer Privatwaldeigentümern | Structure, behavior and perceptions of Swiss private forest owners
Authors: Zimmermann Willi , Wild-Eck Stephan
Published: August 2007

More than a fourth of the Swiss forest belongs to private forest owners. Little is known about the demographic structure and attitudes of these 246 000 people. A better understanding of their motivations and attitudes is necessary to be able to optimally design policy measures, e.g. to enhance and secure their provision of timber or of recreational forest.

In this article, selected results of a questionnaire that was sent to a representative group of private forest owners are presented. In particular, aspects such as their demographic structure, attitudes towards agriculture, geographical distances between their home and forest, use of wood, and attitudes toward subsidies are discussed. The selected results of the study show that a change of the demographic structure among the group of private forest owners is taking place and that the impact of financial incentives offered by the government is rather modest.
Privatwaldforschung in Deutschland: Überblick und Folgerungen | Private forest owner research in Germany: Overview and implications
Authors: Mutz Rüdiger
Published: August 2007

This contribution aims to give a summary about the research of private forests in Germany by summarizing the forest structure, enumerating themes and trends, and illustrating four studies. The private forests in Germany share 43.6% on the total forest area (EU-average: 65%), the largest percentage of the German forest area in comparison to state or communal forests. In private forests considerably less wood is utilized as is grown again. Furthermore, private forests are actually prone to drastic structural changes in combination with the structural crisis of agriculture. Beyond the traditional agricultural forest owner a new type of forest owner is appearing,so-called «urban» forest owner. For further research meta-analysis, an evaluation of advisory service programs and forest funds are discussed.
Privatwald in Österreich – neu entdeckt | Private forest property in Austria – newly discovered
Authors: Weiss Gerhard , Hogl Karl , Rametsteiner Ewald , Sekot Walter
Published: August 2007

Around 80% of the Austrian forest area is private property. Recently, in addition to traditional and business economic research, sciences for sociology and innovation have also discovered the private forest property as a research subject. With respect to different property types, it is shown that the Austrian forest belongs more and more to non-traditional forest owners who show little interest in forestry. For years the actual wood production decreases significantly where rationalization (large forest properties) or adjustments of the timber production to price fluctuations (small forest properties) are taken as counter measures. In general, the intensity and type of innovation activity strongly depends on the size of the property.
Carbonylation
Authors: Bertleff Werner , Roeper Michael , Sava Xavier
Published: August 2007

The article contains sections titled:1.Introduction2.Catalysts2.1.Nickel Catalysts2.2.Cobalt Catalysts2.3.Palladium Catalysts2.4.Rhodium and Iridium Catalysts3.Carbonylation of Alkynes3.1.Acrylic Acid from Acetylene3.2.Other Carbonylation Reactions of Alkynes4.Carbonylation of Alkenes4.1.Monoalkenes4.2.Substituted Alkenes4.3.Polyenes5.Carbonylation of Alcohols and Ethers5.1.BASF Acetic Acid Process5.2.Monsanto Acetic Acid Process5.3.Carbonylation of Other Alcohols and Ethers6.Carbonylation of Organic Halides6.1.Aryl Halides6.2.Alkyl Halides6.3.Allyl Halides and Vinyl Halides7.Other Carbonylation Reactions7.1.Amines7.2.Aromatic Nitro Compounds7.3.Esters7.4.Lactones and Aldehydes7.5.Amidocarbonylation of Aldehydes
Lignin
Authors: Saake Bodo , Lehnen Ralph
Published: August 2007

The article contains sections titled:1.Occurrence and Functions2.Structure and Biosynthesis3.Physical Properties4.Chemical Properties4.1.Kraft Pulping4.2.Sulfite Pulping4.3.Other Pulping Processes4.4.Pulp Bleaching4.5.Yellowing Reactions5.Commercial Lignins6.Analysis6.1.Detection and Quantification6.2.Isolation6.3.Spectroscopic Methods6.4.Degradation Methods6.5.Molar Mass Determination7.Uses8.Toxicology
Hydrocyclones
Authors: Ortega‐Rivas Enrique
Published: August 2007

1.

Introduction

1.1

General Remarks

1.2

Principle of Operation

2.

Categories and Applications

2.1

Thickening

2.2

Clarification

2.3

Classification

2.4

Other Applications

3.

Theoretical Background

3.1

Simultaneous Flow of Fluids and Solids

3.1.1

Dynamics of Particles Submerged in Fluids

3.1.3

Rheology of Suspensions

3.1.4

Flow of Suspension

3.2

Flow Patterns in Hydrocylones

3.3

Mechanics of Particle Separation

3.3.1

Equilibrium‐Orbit Theory

3.3.2

Residence‐Time Theory

3.3.3

Crowding Theory

3.3.4

Turbulent two‐phase Flow Theory

3.4

Characteristics of Performance of Hydrocylones

3.4.1

Separation Efficiency. Cut Size

3.4.2

Capacity. Pressure Drop

4.

Effect of Variables on Hydrocyclone Performance

4.1

Operating Variables

4.2

Design Variables

5.

Selection and Design of Hydrocyclone Systems

5.1

Analytical Solutions

5.2

Graphical Solutions

5.3

Manufacturers' Choice

5.4

Dimensionless Scale‐up

5.4.1

Introduction

5.4.2

Definitions and Derivations of Dimensionless Groups

5.4.3

Scale‐Up at Low Concentrations

5.4.4

Scale‐Up at High Concentrations

5.4.5

Considerations for Non‐Newtonian Behavior

5.4.6

Empirical Models

5.4.7

Practical Applications

Hydrocyclone technology has been suggested as a practical alternative for solid–liquid separations in many applications in diverse industries. The hydrocyclone is easy to install, test and operate, and requires very limited space. It represents an unsophisticated piece of equipment which runs in a continuous manner and it can be operated at lower costs than most of the solid–liquid separation devices. Hydrocyclones have been used in liquid–solid, liquid–liquid, or liquid–gas separations, and can perform varied duties in industries as diverse as mineral processing, chemical engineering, food processing, biotechnology, oil and gas. They have been used not only as separators, but also as clarifiers, classifiers, and in some other applications. This article reviews theoretical aspects of hydrocyclone operation and gives some insight into different applications of hydrocyclone technology.
Radial‐Flow Packed‐Bed Reactors
Authors: Li Jeff C. H.
Published: August 2007

The article contains sections titled:

1.

Introduction

2.

Applications of Radial‐Flow Reactors

3.

Design of Commercial Radial‐Flow Reactors

4.

Flow Distribution

5.

Catalyst Basket Design

6.

Catalyst Settling and Flow Bypassing

7.

Acknowledgments

The radial‐flow packed‐bed reactor is a design with very small pressure drop and most suitable for large‐capacity plants. It has replaced the axial‐flow reactor for several important chemical processes such as ammonia synthesis, ethylbenzene dehydrogenation, and catalytic reforming. The design of a radial‐flow reactor is more complicated than that of an axial‐flow reactor; it must deal with several unique concerns: flow distribution along the length of the reactor, thermal reaction in the void space, catalyst settling, and expansion and contraction of the catalyst basket. The successful operation of a commercial radial‐flow reactor lies mainly in the details of the mechanical design.
Dynamic effects for two‐phase flow in porous media: Fluid property effects
Authors: Das Diganta Bhusan , Gauldie Robert , Mirzaei Mahsanam
Published: August 2007

Traditional descriptions of multiphase flow in porous media rely on an extension of Darcy's law along with relationships between capillary pressure (Pc), saturation (S), and relative permeability (Kr). New theories have been proposed which suggest that Pc relationships should include a dynamic coefficient (τ) (Hassanizadeh and Gray, Water Resour Res. 1993;29:3389–3405) to indicate how “quickly” or “slowly” flow equilibrium is reached. While validity of these theories must be examined, it is also necessary to determine the significance of τ and its range of values. In this article, we analyze the significance of τ depending on fluid properties. We address the ways in which they cause nonuniqueness of dynamic two‐phase flow in porous media and, hence, dynamic effect. Simulations are conducted for quasi‐static and dynamic flow of perchloroethylene (PCE) in water saturated domains. The data are then fitted to the dynamic Pc relationships to obtain values of τ. The effects of flow directions and, viscosity and density ratios are discussed. To consider the lumped effects of various fluid properties, τ–S relationships are examined for silicone oils. The results are interpreted by examining the correlation between τ and a mobility coefficient, m. We discuss a scaling relationship that shows the dependence of τ on fluid and material properties. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Synthesis and characterization of diorganotin(IV) complexes of Schiff bases with ONO‐type donors and crystal structure of [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV)
Authors: Çelebier Mustafa , Şahin Ertan , Ancın Nilgün , Öztaş Nurşen Altuntaş , Öztaş Selma Gül
Published: August 2007

A series of neutral complexes, namely, [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐hydroxysalicylideneiminato]‐ diphenyltin(IV) (Ia), [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐methoxysalicylideneiminato]diphenyltin(IV) (IIa) and [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV) (IIIa) were prepared by the reaction of diphenyltin dichloride on the corresponding Schiff bases. The Schiff bases were the reaction products of 2‐hydroxy‐4‐nitroaniline and appropriate salicylaldehydes. All the compounds were characterized by elemental analysis, 1H‐NMR, 13C‐NMR, IR and mass spectroscopy. Compound IIIa was also characterized by single crystal X‐ray diffraction and shows a C2NO2 coordination geometry nearly half‐way between a trigonal bipyramidal and square pyramidal arrangement. In the solid state, π− π interactions exist between the aniline fragments of neighbouring molecules. Copyright © 2007 John Wiley & Sons, Ltd.
Depolymerization during nitroxide‐mediated oxidation of native cellulose
Authors: Milichovsky Miloslav , Sopuch Tomáš , Richter Jaroslav
Published: August 2007

The kinetics and mechanism of depolymerization during nitroxide‐mediated oxidation of native cellulose has been studied under various conditions. The physical heterogeneity of the native cellulose and its complicated hypermolecular and supramolecular structure exerts a remarkable influence on the kinetics of oxidation and depolymerization. A strong influence of external tension applied on cellulose gauze reactivity during its oxidation has been proven, which is caused by its complicated hypermolecular structure. Celluloronic acids were obtained by the application of external tension during selective oxidation of native cellulose textiles. The cellouronic acids contained the higher amount of carboxyl groups but they also had a lower intrinsic viscosity, i.e., the average degree of polymerization (DP). The mathematical model—so‐called DP‐peeling off model—has been derived to describe the kinetics of cellulose depolymerization based on experimental data obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Alignment of electrospun polystyrene with an electric field
Authors: Chanunpanich N. , Byun Hongsik
Published: August 2007

Polystyrene (PS) with a concentration of 20% by weight in THF/DMF was electrospun on a flat sheet collector. At a concentration of THF above 75%, blocking at the needle tip caused bead formation. However, a nice fiber mat was obtained with the 75/25 THF/DMF. Moreover, at a traveling distance of 10 and 15 cm and voltages from 10 to 16 kV, the PS fibers exhibited alignment. This alignment was reproducible when voltage stabilizer was connected to the voltage supply. This suggested that the uniformly positive charges arising from external voltage interacted with the aromatic rings on the PS chain, yielding a uniform dipole moment. As a result, during jet traveling, the solvent evaporated and the molecules were oriented and frozen at the ground collector. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Polyetherols obtained from 6‐aminouracil and ethylene carbonate
Authors: Chmiel‐Szukiewicz Elżbieta
Published: August 2007

The reactions of 6‐aminouracil with ethylene carbonate were investigated. Potassium carbonate or 1,4‐diazabicyclo[2.2.2]octane was used as a catalyst. An excess of ethylene carbonate was applied in the syntheses. In this way, polyetherols with 1,3‐pyrimidine rings in their structure were prepared. The structure of the products was analyzed with infrared, proton nuclear magnetic resonance, and matrix‐assisted laser desorption/ionization time‐of‐flight techniques. Some physical properties and the thermal stability of the prepared polyetherols were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Preparation of multiwalled carbon nanotube/nylon‐6 nanocomposites by in situ polymerization
Authors: Saeed Khalid , Park Soo‐Young
Published: August 2007

Multiwalled carbon nanotube/nylon‐6 nanocomposites (MWNT/nylon) were prepared by in situ polymerization, whereby pristine MWNTs (P‐MWNTs) and purified MWNTs (A‐MWNTs) were used as reinforcing materials. The A‐MWNTs were purified by nitric acid treatment, which introduced the carboxyl groups (COOH) to the MWNTs. The SEM micrographs from the fractured surfaces of the nanocomposites showed that the A‐MWNTs were well dispersed in A‐MWNT/nylon as compared to the P‐MWNTs in P‐MWNT/nylon. The percolation thresholds of P‐MWNT/nylon and A‐MWNT/nylon, which were studied by rheological properties, were found at ∼ 1 wt % of the MWNTs. The conductivity of P‐MWNT/nylon and A‐MWNT/nylon were 3.15 × 10−5 and 7.46 × 10−5 S/cm by the loading of 5 and 7 wt % of MWNTs, respectively. Differential scanning calorimetry (DSC) showed that the crystallization temperatures of P‐MWNT/nylon and A‐MWNT/nylon (195°C) increased more than that of pure nylon (189°C) due to the nucleation effect of MWNTs. Wide‐angle X‐ray analysis indicated that the incorporation of MWNTs into the nylon matrix resulted only in α‐crystalline structure, which were quite different from those reported for the clay/nylon nanocomposite (show both α‐ and γ‐crystals). It might be due to the different geometry between the MWNTs and the nanoclay platelets, which have one and two‐dimensional geometry, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Moldability and properties of phenolic/artificial zeolite composites
Authors: Matsumoto Akihiro , Ohtsuka Keiko , Kimura Hajime , Adachi Shin‐ich , Takenaka Minoru
Published: August 2007

The purpose of this study is to improve the several properties of composites consisting of a phenolic and fly ash or artificial Zeolite such as sodium type Zeolite (NaZe) or calcium type Zeolite(CaZe). And it also includes the improvement in the flowability of molding compounds. The molding compounds were prepared from a phenol novolac, a curing agent, and several fillers. The flowability of the compounds containing fly ash and artificial Zeolite as a filler, mentioned above, was superior to that of the compounds containing glass fiber (GF), calcium carbonate (CaCO3), or talc as a filler. The phenolic composites were prepared from the above molding compounds by transfer molding. The phenolic composite containing CaZe had most superior heat resistance, electrical insulation, and flexural strength, though in the lastly listed property it ranked next to the GF‐filled composite. The linear expansion coefficient of the composite containing CaZe was as low as almost isotropic. The reasons of obtaining these excellent properties were thought to be as follows: (1) CaZe could finely be dispersed in the phenolic resin to bring good impregnation. (2) The surface chemical and physical interaction between the resin and CaZe was higher than that between the resin and the other fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007