bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of the Femoral Neck During Growth Determines Its Strength in Old Age
Authors: Zebaze Roger M D , Jones Anthony , Knackstedt Mark , Maalouf Ghassan , Seeman Ego
Published: March 2007

Study of the design of the FN in vivo in 697 women and in vitro in 200 cross-sections of different sizes and shapes along each of 13 FN specimens revealed that strength in old age was largely achieved during growth by differences in the distribution rather than the amount of bone material in a given FN cross-section from individual to individual.

Introduction: We studied the design of the femoral neck (FN) to gain insight into the structural basis of FN strength in adulthood and FN fragility in old age.

Materials and Methods: Studies in vivo were performed using densitometry in 697 women and in vitro using high-resolution μCT and direct measurements in 13 pairs of postmortem specimens.

Results: The contradictory needs of strength for loading yet lightness for mobility were met by varying FN size, shape, spatial distribution, and proportions of its trabecular and cortical bone in a cross-section, not its mass. Wider and narrower FNs were constructed with similar amounts of bone material. Wider FNs were relatively lighter: a 1 SD higher FN volume had a 0.67 (95% CI, 0.61–0.72) SD lower volumetric BMD (vBMD). A 1 SD increment in height was achieved by increasing FN volume by 0.32 (95% CI, 0.25–0.39) SD with only 0.15 (95% CI, 0.08–0.22) SD more bone, so taller individuals had a relatively lighter FN (vBMD was 0.13 [95% CI, 0.05–0.20 SD] SD lower). Greater periosteal apposition constructing a wider FN was offset by even greater endocortical resorption so that the same net amount of bone was distributed as a thinner cortex further from the neutral axis, increasing resistance to bending and lowering vBMD. This was recapitulated at each point along the FN; varying absolute and relative degrees of periosteal apposition and endocortical resorption focally used the same amount of material to fashion an elliptical FN of mainly cortical bone near the femoral shaft to offset bending but a more circular FN of proportionally more trabecular and less cortical bone to accommodate compressive loads adjacent to the pelvis. This structural heterogeneity was largely achieved by adaptive modeling and remodeling during growth—most of the variance in FN volume, BMC, and vBMD was growth related.

Conclusions: Altering structural design while minimizing mass achieves FN strength and lightness. Bone fragility may be the result of failure to adapt bone's architecture to loading, not just low bone mass.
Identification of Sex-Specific Associations Between Polymorphisms of the Osteoprotegerin Gene, TNFRSF11B, and Paget's Disease of Bone
Authors: Beyens Greet , Daroszewska Anna , de Freitas Fenna , Fransen Erik , Vanhoenacker Filip , Verbruggen Leon , Zmierczak Hans-Georg , Westhovens René , Van Offel Jan , Ralston Stuart H , Devogelaer Jean-Pierre , Van Hul Wim
Published: March 2007

We studied the role of TNFRSF11B polymorphisms on the risk to develop Paget's disease of bone in a Belgian study population. We observed no association in men, but a highly significant association was found in women, and this was confirmed in a population from the United Kingdom.

Introduction: Juvenile Paget's disease has been shown to be caused by mutations in TNFRSF11B encoding osteoprotegerin. Although mutations in this gene have never been found in patients with typical Paget's disease of bone (PDB), there are indications that polymorphisms in TNFRSF11B might contribute to the risk of developing PDB.

Materials and Methods: We recruited a population of 131 Belgian patients with sporadic PDB and 171 Belgian controls. By means of the HapMap, we selected 17 SNPs that, in combination with four multimarker tests, contain most information on common genetic variation in TNFRSF11B. To replicate the findings observed in the Belgian study population, genotyping data of SNPs generated in a UK population were reanalyzed.

Results: In our Belgian study population, associations were found for two SNPs (rs11573871, rs1485286) and for one multimarker test involving rs1032129. When subsequently analyzing men and women separately, these associations turned out to be driven by women (56 cases, 78 controls). In addition, three other tagSNPs turned out to be associated in women only. These were rs2073617 (C950T), rs6415470, and rs11573869. Reanalysis of genotyping data from a UK study population indicated that the associations found for C950T and C1181G were also exclusively driven by women (146 cases, 216 controls). Meta-analysis provided evidence for risk increasing effects of the T allele of C950T and the G allele of C1181G in the female population (p = 0.002 and 0.003, respectively). The haplotypes formed by the SNPs associated in the Belgian population were also distributed differentially between female cases and controls.

Conclusions: We showed for the first time that SNPs influencing the risk to develop PDB could be sex-specific. Further research is necessary to identify the causative variants in TNFRSF11B and to elucidate the molecular pathogenic mechanism.
Accounting Discretion and Managerial Conservatism: An Intertemporal Analysis*
Authors: Lin Haijin
Published: March 2007

Accounting discretion and the principle of conservatism are two salient features embedded in financial reporting systems. Arguably, the practice of conservative accounting choices can never be well understood without incorporating their effect on future periods (the intertemporal effect). This paper provides one explanation for managerial conservatism in a two‐period agency model with hidden information (a binary project type) and hidden actions (the agent's efforts). A piece‐wise linear incentive scheme with accounting earnings as the performance measure is employed. The agent's discretion is the choice of a depreciation method. Discretion is valuable if and only if the agent's marginal productivity of a “bad” project is greater than that of a “good” project, but not to an extreme degree. A conservative depreciation method decreases current compensation in exchange for a “bet” on future compensation and, hence, serves as a commitment device for the agent to signal that the prospect is indeed good. The accounting mechanism replicates the performance of the optimal direct mechanism.
Auditor Reputation, Auditor Independence, and the Stock‐Market Impact of Andersen's Indictment on Its Client Firms*
Authors: Krishnamurthy Srinivasan , Zhou Jian , Zhou Nan
Published: March 2007

In this paper, we study a broad sample of Arthur Andersen clients and investigate whether the decline in Andersen's reputation, due to its criminal indictment on March 14, 2002, adversely affected the stock market's perception of its audit quality. Because these reputa‐tional concerns are more of an issue if an auditor's independence is impaired, we investigate the relationship between the abnormal market returns for Andersen clients around the time of the indictment announcement and several fee‐based measures of auditor independence. Our results suggest that when news about Andersen's indictment was released, the market reacted negatively to Andersen clients. More importantly, we find that the indictment period abnormal return is significantly more negative when the market perceived the auditor's independence to be threatened. We also examine the abnormal returns when firms announced the dismissal of Andersen as an auditor. Consistent with the audit quality explanation, we document that when firms quickly dismissed Andersen, the announcement returns are significantly higher when firms switched to a Big 4 auditor than when they either switched to non‐Big 4 auditors or did not announce the identity of the replacement auditor. Our empirical results support the notion that auditor reputation and independence have a material impact on perceived audit quality and the credibility of audited financial statements, and that the market prices this.
Forces Leading to the Adoption of Accrual Accounting by the Canadian Federal Government: An Institutional Perspective*/ LES FORCES AYANT MENÉ L'ADMINISTRATION FÉDÉRALE CANADIENNE À ADOPTER LA COMPTABILITÉ D'EXERCICE: UNE PERSPECTIVE INSTITUTIONNELLE
Authors: BAKER RON , RENNIE MORINA D.
Published: March 2007

In 1995, the federal government of Canada announced that it would adopt full accrual accounting. The change was fully implemented at the department level in 2001 and for government‐wide financial reporting in 2003. Using the perspective of institutional theory, we examine several factors that had the potential to influence the federal government's decision to adopt full accrual accounting, including two royal commissions, the Office of the Auditor General of Canada, the Canadian Institute of Chartered Accountants, credit markets, and the practices of other national governments. We find that the decision to change to accrual accounting can be largely attributed to coercive and normative influences of the Office of the Auditor General of Canada (supported by the normative influence of the Canadian Institute of Chartered Accountants' Public Sector Accounting Board) and mimetic isomorphism with other members of the federal government's organizational field.
Nonaudit Services and Earnings Conservatism: Is Auditor Independence Impaired?*
Authors: Ruddock Caitlin , Taylor Sarah J. , Taylor Stephen L.
Published: March 2007

We examine whether the provision of nonaudit services (NAS) by incumbent auditors is associated with a reduction in the extent to which earnings reflect bad news on a timely basis (that is, news‐based conservatism). Reduced conservatism is expected to occur if relatively high levels of NAS result in reduced auditor independence and, ultimately, lower‐quality auditing. Because client‐specific demand for NAS is expected to vary, our proxy for the auditor‐client economic bond is the extent to which NAS purchases (relative to audit fees) are greater or less than expected. Using several different methods for identifying news‐based conservatism, we consistently find that higher than expected levels of NAS are not associated with reduced conservatism. This result is robust to allowing for endogenous NAS demand, as well as several explicit factors that may be associated with differences in conservatism. Similar conclusions arise from tests that use alternative measures of the economic bond between auditors and their clients, as well as in tests confined to either the Big 6 or non‐Big 6 audit firms. Our results are consistent with factors such as market‐based incentives, the threat of litigation, and alternative governance mechanisms offsetting any expected benefits to the audit firm from reducing its independence. We therefore conclude that recent legislative intervention aimed at restricting the supply of NAS is unlikely to result in increased independence in fact, although independence in appearance may be improved.
Conservative Accounting and Linear Information Valuation Models*
Authors: Choi Young‐Soo , O'Hanlon John F. , Pope Peter F.
Published: March 2007

Prior research using the residual income valuation model and linear information models has generally found that estimates of firm value are negatively biased. We argue that this could result from the way in which accounting conservatism effects are reflected in such models. We build on the conservative accounting model of Feltham and Ohlson 1995 and the Dechow, Hutton, and Sloan 1999 (DHS) methodology to propose a valuation model that includes a conservatism‐correction term, based on the properties of past realizations of residual income and “other information”. “Other information” is measured using analyst‐forecast‐based predictions of residual income. We use data comparable to the DHS sample to compare the bias and inaccuracy of value estimates from our model and from models similar to those used by DHS and Myers 1999. Valuation biases are substantially less negative for our model, but valuation inaccuracy is not markedly reduced.
Earnings Quality and the Equity Risk Premium: A Benchmark Model*
Authors: Yee Kenton K.
Published: March 2007

This paper solves a model that links earnings quality to the equity risk premium in an infinite‐horizon consumption capital asset pricing model (CAPM) economy. In the model, risk‐averse traders hold diversified portfolios consisting of risk‐free bonds and shares of many risky firms. When constructing their portfolios, traders rely on noisy reported earnings and dividend payments for information about the risky firms. The main new element of the model is an explicit representation of earnings quality that includes hidden accrual errors that reverse in subsequent periods.

The model demonstrates that earnings quality magnifies fundamental risk. Absent fundamental risk, poor earnings quality cannot affect the equity risk premium. Moreover, only the systematic (undiversified) component of earnings‐quality risk contributes to the equity risk premium. In contrast, all components of earnings‐quality risk affect earnings capitalization factors. The model ties together consumption CAPM and accounting‐based valuation research into one price formula linking earnings quality to the equity risk premium and earnings capitalization factors.
CAP Forum on Forensic Accounting in the Post‐Enron World: Audit Committees and Misappropriation of Assets: Publicly Held Companies in the United States*/LES COMITÉS DE VÉRIFICATION ET LE DÉTOURNEMENT DE BIENS: LES SOCIÉTÉS OUVERTES AUX ÉTATS‐UNIS
Authors: MUSTAFA SAMEER T. , MEIER HEIDI HYLTON
Published: March 2007

The majority of previous studies investigating the different risk factors associated with financial fraud have focused on investigating misreporting. A few studies have provided only a limited descriptive analysis of cases involving misappropriation of assets without investigating the corporate governance structure and its role in reducing the incidence of misappropriation. Only Beasley (1996) has examined financial fraud and corporate governance structure by combining cases of misreporting and misappropriation of assets by top management.

This study investigates the relationship between the incidence of misappropriation of assets by employees, including management, and the effectiveness of the audit committee. Using LEXIS‐NEXIS Research Software 7.1, Business/Finance News to find relevant articles, we identified publicly held companies suffering misappropriation of assets by employees during the period from 1987 to 2000. The study investigated 81 companies experiencing misappropriation and two control samples: 81 random‐control companies and 81 matched‐control companies.

The results extend the previous literature related to financial fraud and corporate governance. The percentage of independent members in audit committees and the average tenure of audit committee members were significantly and negatively related to the incidence of misappropriation of assets in publicly held companies in both the random and the matched models, while the number of audit committee meetings was not significant.
Auditor Independence in Canada: A Historical Perspective — From Shareholder Auditors to Modern‐Day Audit Committees*
Authors: GREEN DUNCAN L.
Published: March 2007

This paper uses the theoretical framework of Goldman and Barlev (1974) to examine auditor independence in Canada. It traces the historical development of the auditor's role in the 19th century and the beginning of the auditor's relationship with shareholders and management. It shows how, following the separation of management from shareholding, management's ability to influence auditors undermined auditor independence. The paper traces attempts by legislators and regulatory bodies to limit management's influence over auditors and to correct the asymmetry of their relationship. It notes that recent changes to legislation and rules of professional conduct are no longer proactive, but are reactions to corporate scandals in Canada and the United States. The paper argues that although future changes will occur to redress the imbalance, only structural changes are likely to provide a real solution to auditor independence problems. However, it is likely that such changes will be resisted by the accounting profession.
Recognition versus Disclosure of Stock Option Compensation: An Analysis of Judgements and Decisions of Nonprofessional Investors*/CONSTATER OU PRÉSENTER PAR VOIE DE NOTE LA RÉMUNÉRATION SOUS FORME D'OPTIONS D'ACHAT D'ACTIONS: UNE ANALYSE DES JUGEMENTS ET DES DÉCISIONS DES INVESTISSEURS NON PROFESSIONNELS
Authors: BELZILE RÉJEAN , FORTIN ANNE , VIGER CHANTAL
Published: March 2007

Given the importance of stock options in the aggregate compensation of chief executive officers and other firm employees in the 1990s and early 2000s, the International Accounting Standards Board issued an International Financial Reporting Standard on stock‐based payments on February 19, 2004, requiring that all share‐based payment transactions be recognized at fair value in entities' financial statements. The Canadian Institute of Chartered Accountants' Accounting Standards Board had already agreed to this principle and amended section 3870 of the CICA Handbook (stock‐based compensation) for financial periods beginning on or after January 1, 2004, making Canada the first major jurisdiction to require all public companies to expense employee stock‐based compensation awards. The revised section eliminated the possibility of disclosing pro forma net income and earnings per share only by way of a note.

This research, conducted as a between‐subjects experiment with executive MBA students as nonprofessional investors, examines whether changes in the way stock option compensation is reported (recognition as an expense in the income statement or note disclosure of pro forma net income and earnings per share) affect financial statement users' judgements and investment decisions. Our results indicate that, consistent with the functional fixation hypothesis, the reporting method does indeed significantly influence subjects' judgement of the expected stock price direction, but has no material influence on their investment decisions.
The Importance of Account Relations when Responding to Interim Audit Testing Results*
Authors: Vandervelde Scott D.
Published: March 2007

Auditors are expected to plan and adapt audit programs in response to changes in risk associated with each client. Results in the existing research have been mixed regarding whether auditors respond to changes in risk. Two possible explanations for the lack of responsiveness to changes in risk found in the existing research are that auditors succumb to profit pressure, and that researchers only analyze responses in the risky accounts without considering related accounts. This paper experimentally tests how auditors respond to changes in risk of material misstatement identified by means of interim audit testing results. The response to changes in risk of material misstatement is analyzed using planned audit hours across related financial statement accounts and at varying levels of profit pressure. Results indicate the following primary findings: (a) auditors respond to changes in risk of material misstatement by increasing planned audit hours in accounts related to the risky account, and (b) profit pressure does not affect the auditor's response to changes in risk. These results indicate that the relations between accounts must be considered in order to identify the auditors' response to changes in risk of material misstatement. In addition, the results are consistent with audit firms decreasing the emphasis on profit pressure due to the current importance that the market places on audit quality.
The Efficacy of Third‐Party Consultation in Preventing Managerial Escalation of Commitment: The Role of Mental Representations*
Authors: KADOUS KATHRYN , SEDOR LISA M.
Published: March 2007

Avoiding continued investment in poorly performing projects is an important function of management control systems. However, prior research suggests that managers fail to use accounting information indicating that a project is performing poorly to discontinue it; that is, they escalate commitment to the project. We perform two experiments to investigate the efficacy of a potential control mechanism, third‐party consultation, in preventing managerial escalation of commitment. We hypothesize that the information‐processing objective (that is, purpose) assigned to consultants influences the mental representations they construct to process and store information, which ultimately influences their recommendations regarding the continuation of a poorly performing project. Results suggest that consultants will not construct mental representations amenable to making high‐quality project‐continuation recommendations unless they are assigned that specific purpose. Results further suggest that applying additional effort likely will not overcome the adverse effects of having inappropriate mental representations when making project‐continuation recommendations. An implication of our study is that third‐party consultants likely will not prevent managerial escalation of commitment unless consultants have a specific mandate of making a project‐continuation recommendation in mind when they encounter relevant accounting information.
Publishing in the Majors: A Comparison of Accounting, Finance, Management, and Marketing*
Authors: SWANSON EDWARD P.
Published: March 2007

Business schools evaluate publication records, especially for the promotion and tenure decision, by comparing the quality and quantity of a candidate's research with those of peers within the same discipline (intradisciplinary) and with those of academics from other business disciplines (interdisciplinary). A recently developed analytical model of the research review process provides theory about the norms used by editors and referees in deciding whether to publish research papers. The model predicts that interdisciplinary differences exist in quality norms, which could result in disparity among business disciplines in the number of top‐tier articles published. I examine the period from 1980 to 1999 and, consistent with the theory, find that significant differences exist in the number of articles and proportion of doctoral faculty who published in the “major” journals in accounting, finance, management, and marketing. Most notably, the proportion of doctoral faculty publishing a major article is 1.4 to 2.4 times greater in the other business disciplines than in accounting (depending on the set of journals). The theory also predicts an upward drift over time in the quality norms used by referees. Consistent with a drift, the number of articles published has declined substantially in marketing and, to a lesser extent, in the other business disciplines.
Tax‐Avoidance Activities of U.S. Multinational Corporations*
Authors: Rego Sonja Olhoft
Published: March 2007

This paper investigates whether economies of scale exist for tax planning. In particular, do larger, more profitable, multinational corporations avoid more taxes than other firms, resulting in lower effective tax rates? While the empirical results indicate that, ceteris paribus, larger corporations have higher effective tax rates, firms with greater pre‐tax income have lower effective tax rates. The negative relation between effective tax rates (ETRs) and pretax income is consistent with firms with greater pre‐tax income having more incentives and resources to engage in tax planning.

Consistent with multinational corporations being able to avoid income taxes that domestic‐only companies cannot, I find that multinational corporations in general, and multinational corporations with more extensive foreign operations, have lower worldwide ETRs than other firms. Finally, in a sample of multinational corporations only, I find that higher levels of U.S. pre‐tax income are associated with lower U.S. and foreign ETRs, while higher levels of foreign pre‐tax income are associated with higher U.S. and foreign ETRs. Thus, large amounts of foreign income are associated with higher corporate tax burdens. Overall, I find substantial evidence of economies of scale to tax planning.
Are Securitizations in Substance Sales or Secured Borrowings? Capital‐Market Evidence*
Authors: Niu Flora F. , Richardson Gordon D.
Published: March 2007

Two standard‐setting approaches have emerged globally to guide the choice of accounting for securitizations: the control and components approach (SFAS No. 125 and SFAS No. 140) and the risks and rewards transfer approach (IAS No. 39). A lack of consensus about derecognition accounting is a major impediment to achieving convergence in global standards that must be resolved. Thus, both SFAS No. 140 and IAS No. 39 will be reexamined, and evidence pertinent to the debate is timely and important. In this study, we present evidence consistent with the view of credit‐rating analysts, who view many securitizations as, in substance, secured borrowings. Specifically, for a sample of originators applying sale accounting guidance in SFAS No. 125 / 140 during the period 1997‐2003, we show that off‐balance‐sheet debt related to securitizations has, on average, the same risk‐relevance for explaining market measures of risk (that is, CAPM beta) as on‐balance‐sheet debt. We also find that, in a returns and earnings association framework, the pricing multiple on securitization gains declines as the amount of off‐balance‐sheet debt increases, implying that investors take off‐balance‐sheet debt into account when assessing the valuation‐relevance of such gains. For those who advocate the control and components approach to securitization accounting, our results suggest that, at least for frequent securitizers, the put option arising from implicit recourse is a “missing piece” that is not currently accounted for when calculating securitization gains. Our results challenge the extant measurement standards in SFAS No. 140.
Association Between Congenital Heart Defects and Small for Gestational Age
Authors: Malik Sadia , Cleves Mario A. , Zhao Weizhi , Correa Adolfo , Hobbs Charlotte A. ,   and the National Birth Defects Prevention Study
Published: March 2007

OBJECTIVES. Infants with congenital heart defects may experience inhibited growth during fetal life. In a large case-control study, we addressed the hypothesis that infants with congenital heart defects are more likely to be small for gestational age than infants without congenital heart defects after controlling for selected maternal and infant characteristics.

METHODS. Using data from population-based birth defect registries, the National Birth Defects Prevention Study enrolled infants with nonsyndromic congenital heart defects (case subjects) and infants without congenital heart defects or any other birth defect (control subjects). Small for gestational age was defined as birth weight below the 10th percentile for gestational age and gender. Association between congenital heart defects and small for gestational age was examined by conditional logistic regression adjusting for maternal covariates related to fetal growth.

RESULTS. Live-born singleton infants with congenital heart defects (case subjects, n = 3395) and live-born singleton infants with no birth defect (control subjects, n = 3924) were included in this study. Case subjects had lower birth weights compared with control subjects. Small for gestational age was observed among 15.2% of case subjects and among only 7.8% of control subjects. Congenital heart defect infants were significantly more likely to be small for gestational age than control infants.

CONCLUSIONS. Infants with congenital heart defects are approximately twice as likely to be small for gestational age as control subjects. Small for gestational age status may affect clinical management decisions, therapeutic response, and prognosis of neonates with congenital heart defects. Although the etiology of growth retardation among infants with congenital heart defects is uncertain, further exploration may uncover a common pathogenesis or causal relationship between congenital heart defects and small for gestational age.
Field monitoring evaluation of geotextile-reinforced soil-retaining walls
Authors: Benjamim C. V. S. , Bueno B. S. , Zornberg J. G.
Published: March 2007

The use of geotextiles as reinforcement in soil-retaining walls may offer benefits over the use of other types of reinforcement, such as metallic strips or geogrids. These include ease of construction, expediency, and significant cost reduction. However, the lack of field monitoring results documenting the behavior of geotextile-reinforced structures, mainly regarding deformations, has precluded widespread utilization of these systems. A better understanding of the behavior of geotextile-reinforced soil structures could be gained by systematic monitoring of full-scale structures, combined with a thorough material characterization program. Accordingly, eight prototype geotextile-reinforced soil structures were built as part of a comprehensive study aimed at analyzing their behavior. This paper presents the characteristics of the prototype wall used as baseline for this series of structures, including construction details, instrumentation layout, and the results of laboratory tests conducted to characterize the soils and geosynthetics involved in this structure. The lateral displacements at the face of the wall were small, with increasing lateral displacements observed over time, particularly in association with precipitation events during the summer season in Brazil. The largest horizontal strains occurred towards the face, at mid-height of the prototype wall. The use of sigmoid curves to fit displacement results within the geotextiles was found to be very useful to define the value and the location of the peak strain in each reinforcement layer. The location of maximum reinforcement strains within each layer was found to be consistent with the development of a potential failure surface starting at the toe of the wall and propagating into the soil mass. The maximum reinforcement tension predicted using the K-stiffness method was found to compare well with reinforcement tension values obtained from monitoring results.
Numerical studies of ring foundations on geogrid-reinforced sand
Authors: Laman M. , Yildiz A.
Published: March 2007

Numerical predictions of the ultimate bearing capacity of ring foundations supported by a sand bed with and without geogrid reinforcement are presented. Numerical analyses of the test models were carried out using the finite element package Plaxis. It is shown that the behaviour of ring foundations on sand beds may be reasonably well represented by the hardening soil model available in the Plaxis package. The hardening soil model parameters were derived from the results of drained triaxial tests. The parameters investigated are the effect of depth of first reinforcement layer, the number of reinforcement layers and reinforcement layer size on the ultimate bearing capacity of ring foundations. The results from the finite element analysis are in very good agreement with the experimental observations. The results of this study showed that the reinforcement had a considerable effect on the ultimate bearing capacity of the ring foundations. It was also shown that ultimate bearing capacity values can, depending on the reinforcement geogrid arrangement, be improved by up to three times that of the unreinforced case for the model arrangements investigated.
Olivenite-Adamite Solid Solution From Oxidation Zone in Rędziny (West Sudetes, Poland)
Authors: Gołębiowska Boźena , Pieczka Adam , Franus Wojciech
Published: March 2007

Olivenite-Adamite Solid Solution From Oxidation Zone in Rędziny (West Sudetes, Poland)

An extensive hydrothermal polymetallic mineralization with a well developed oxidation zone rich in secondary minerals occurs in dolostones several hundred meters from the Karkonosze granite at Rędziny. Using XRD and FTIR methods, mineral phases representing transitional members of the olivenite-adamite solid solution have been identified. Electron microprobe analyses reveal the most common varieties to be zincian olivenite and cuprous adamite with compositions ranging from (Cu1.17Zn0.83)(AsO4)(OH) to (Zn1.38Cu0.62)(AsO4)(OH). The two minerals are subordinate in the weathering zone which can be characterized as having been a zone of low Cu2+and Zn2+activity and with mineralizing solutions of increased pH. A high Ca2+concentration due to the ubiquitous presence of carbonate rocks resulted in the expansion of the stability field of another arsenate, conichalcite (or Zn-bearing conichalcite), which is a common mineral there.
Włodzimierz Wojciech Kowalski 1932-2005
Authors: Parafiniuk Jan
Published: March 2007

Włodzimierz Wojciech Kowalski 1932-2005
Residual Osl Signals from Modern Greenlandic River Sediments
Authors: Alexanderson Helena
Published: March 2007

Ripple-laminated sandy deposits at shallow water depths in four rivers on Jameson Land, East Greenland were sampled for optically stimulated luminescence (OSL) dating. Silt-sized grains have significantly higher equivalent doses (~1.1 Gy) than sand grains (~0.1 Gy). This suggests that coarse grain-size fractions are better bleached and more suitable than fine grains for OSL dating of glaciofluvial/fluvial sediments. A sample from a sidebar deposited during the spring flood yielded 1.0 Gy (~500 years) while a subaerial deposit was completely zeroed. The spring flood deposit is considered to be most similar to deglacial conditions and incomplete bleaching of this amount (1 Gy) is generally not a significant source of error for sediments of Pleistocene age. Most samples have rather poor luminescence characteristics and are affected by thermal transfer if preheat temperatures at or above 260°C are used.
Quartz Single Grain Osl Sensitivity Distributions: Implications for Multiple Grain Single Aliquot Dating
Authors: Rhodes Edward
Published: March 2007

A simple probabilistic numerical model was used to construct synthetic De distributions by combining the simulated OSL from grains of different sensitivities and with various simulated De values. This is useful for exploring the complex patterns generated by summing the signals from many grains in real, multiple grain OSL dating scenarios, and demonstrates that the form of the sensitivity distribution has a significant effect on the identification of mixed dose populations in multiple grain single aliquot methods. I describe the simple numerical model and its implementation. I present measured quartz single grain OSL sensitivity distributions for an aeolian dune sample from the Simpson Desert, Northern Territory, Australia, and from a suite of 9 fluvial sediments from Namadgi National Park, Australian Capital Territory, Australia, to illustrate effects that result from natural differences. Minimum age model determinations of synthetic De values are used to assess the validity of dose values estimated from multiple grain single aliquot measurements.
Role of germanium L-cysteine α-tocopherol complex as stimulator of some antioxidant defense systems in gamma-irradiated rats
Authors: Ali Mamdouh , Noaman Eman , Kamal Sherien , Soliman Saaed , Ismail Dina
Published: March 2007

Role of germanium L-cysteine α-tocopherol complex as stimulator of some antioxidant defense systems in gamma-irradiated rats

This study was conducted to evaluate the potency of the newly prepared germanium L-cysteine α-tocopherol complex [germanium dichloro tetrakis (L-cysteinyl-α-tocopherol amide) dichloride] as a protective agent against γ-irradiation-induced free radicals production and liver toxicity. Male Swiss albino rats were injected intraperitoneally with the germanium complex in a concentration of 75 mg kg-1 body mass per dose, for 6 successive doses, last dose administered twenty minutes pre-exposure to a single dose of whole body γ-irradiation of 6.5 Gy. Lipid peroxidation (LPx), nitric oxide (NO), glutathione (GSH) levels, and activity of the antioxidant enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were estimated in blood and liver. Blood total protein, cholesterol, triglyceride and α-tocopherol content were estimated as well. The results revealed that administration of germanium complex pre-irradiation resulted in significant (p < 0.001) improvement compared to the irradiated group in the level of hepatic and blood LPx. Hepatic GSH revealed a significant increase (p < 0.001), while its level showed no significant variation in blood. Also, the level of NO in blood and liver increased significantly (p < 0.001). On the other hand, pretreatment with the germanium complex normalized the activities of SOD, GPx and CAT in blood and liver when compared to the irradiated group. The study also documents a marked decrease in a blood triglyceride and cholesterol (p < 0.001) and a significant increase (p < 0.001) of α-tocopherol and total protein contents in blood. These biochemical changes were associated with marked improvement of histological status. Therefore, the germanium L-cysteine α-tocopherol complex may be a good candidate for ameliorating the changes induced by irradiation, which indicates the beneficial radio-protective role of this antioxidant agent.
Studies in 3,4-diaryl-1,2,5-oxadiazoles and their N-oxides: Search for better COX-2 inhibitors
Authors: Yadav Mange , Shirude Shrikant , Puntambekar Devendra , Patel Pinkal , Prajapati Hetal , Parmar Arvind , Balaraman R. , Giridhar Rajani
Published: March 2007

Studies in 3,4-diaryl-1,2,5-oxadiazoles and theirN-oxides: Search for better COX-2 inhibitors

A series of 3,4-diaryl-1,2,5-oxadiazoles and 3,4-diaryl-1,2,5-oxadiazoleN-oxides were prepared and evaluated for COX-2 and COX-1 binding affinityin vitroand for anti-inflammatory activity by the rat paw edema method.p-Methoxy (p-OMe) substituted compounds 9, 21, 34, 41, 42 showed COX-2 enzyme inhibition higher than that showed by compounds with other substituents. 3,4-Di(4-methoxyphenyl)-1,2,5-oxadiazoleN-oxide (42) showed COX-2 enzyme inhibition of 54% at 22 μmol L-1and COX-1 enzyme inhibition of 44% at 88 μmol L-1concentrations, but showed very lowin vivoanti-inflammatory activity. Its deoxygenated derivative (21) showed lower COX-2 enzyme inhibition (26% at 22 μmol L-1) and higher COX-1 enzyme inhibition (53% at 88 μmol L-1) but, markedin vivoanti-inflammatory activity (71% at 25 mg kg-1)vs.celecoxib (48% at 12.5 mg kg-1). Molecular modeling (docking) studies showed that the methoxy group is positioned in the vicinity of COX-2 secondary pocket and it also participates in hydrogen bonding interactions in the COX-2 active site. These preliminary studies suggest thatp-methoxy (p-OMe) group in one of benzene rings may give potentially active leads in this series of oxadiazole/N-oxides.
Physicochemical characterization and in vitro dissolution behaviour of celecoxib-β-cyclodextrin inclusion complexes
Authors: Sinha Vivek , Anitha R. , Ghosh Soma ,   Amita, Kumria Rachana , Bhinge Jayant , Kumar Manoj
Published: March 2007

Physicochemical characterization and in vitro dissolution behaviour of celecoxib-β-cyclodextrin inclusion complexes

In this study, attempts were made to investigate the effects of β-cyclodextrin (β-CD) on the aqueous solubility and dissolution rate of celecoxib. Inclusion complexes were prepared by the kneading method and characterized by SEM, NMR, IR, DSC, and X-ray powder diffraction. Dissolution rate of the complexes was significantly greater than that of the corresponding physical mixtures and pure drug, indicating that the formation of inclusion complex increased the solubility of the poorly soluble drug celecoxib.
In vivo antioxidant potential of Teucrium polium, as compared to α-tocopherol
Authors: Hasani Parisa , Yasa Nargues , Vosough-Ghanbari Sanaz , Mohammadirad Azadeh , Dehghan Gholamreza , Abdollahi Mohammad
Published: March 2007

In vivo antioxidant potential of Teucrium polium, as compared to α-tocopherol

The present study was undertaken to explore antioxidant potential of Teucrium polium (Lamiaceae) in vivo. Antioxidant activity was measured by three tests including inhibition of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, total antioxidant power (TAP), and thiobarbituric acid reactive substances (TBARS) in serum. Rats received dry extract of T. polium in 80% ethanol by intragastric intubation at doses of 50, 100 and 200 mg kg-1 daily for 14 days. Treatment of rats with T. polium extract showed significant antioxidant activity in the DPPH test as compared to the control. T. polium extract at doses of 50 and 100 mg kg-1 significantly increased rats TAP and decreased TBARS compared to the control. Administration of T. polium at a dose of 200 mg kg-1 per day did not significantly alter serum TAP and TBARS. Antioxidant activities of T. polium at a doses of 50 and 100 mg kg-1 were in all experiments comparable to that of α-tocopherol (10 mg kg-1).
Copolymers of 3,3,3‐trifluoropropene and vinyl acetate: Synthesis, characterization, and hydrolysis
Authors: Zhang Shuxiang , Xu Anhou , Geng Bing , Xia Pandeng , Chu Shanzhuang , Liu Min
Published: March 2007

Copolymers based on 3,3,3‐trifluoropropene (TFP) and vinyl acetate (VAc) were synthesized in supercritical carbon dioxide(scCO2). The copolymers were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC) as the thermal analysis method. The copolymer compositions were estimated by three techniques: mass balance, NMR and electric potential analysis. The mole fraction of TFP in the copolymer increased with the feeding TFP added from 12.1% to 76.4% and almost unchanged with a feeding TFP increase from 76.4% to 89.7%. After partial carboxyl groups turned to hydroxyl groups by hydrolysis, the P(TFP‐co‐VAc) copolymer turned into terpolymers, P(TFP‐VAc‐VA). Dispersed in water, the hydrolyzed copolymer obtained emulsion by self‐emulsifying. The size distribution and the morphology of the latex were also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and characterization of a novel pH‐, thermo‐, and ionic strength‐responsive hydrogels based on xanthan gum–poly(aspartic acid)
Authors: Yang Jun , Fang Li , Wang Fang , Tan Tianwei
Published: March 2007

A series of interpenetrating polymer networks (IPN) hydrogels with different compositions that based on xanthan gum (XG) and poly(aspartic acid) (PASP) were synthesized. The effects of various external surrounding stimuli, including pH, temperature, and ionic strength on XG–PASP hydrogels swelling properties were investigated. Chemical structural changes of the IPN hydrogels were characterized by Fourier transform infrared spectroscopy (FT‐IR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and swelling ratio measurement. The swelling process was found to be a Fickian diffusion and reached swelling equilibrium quickly. It was found that the feed composition of PASP was an important factor that affected the properties of IPN hydrogels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Morphology, crystallization, and mechanical properties of poly(ethylene terephthalate)/multiwall carbon nanotube nanocomposites via in situ polymerization with very low content of multiwall carbon nanotubes
Authors: Wang Yang , Deng Jinni , Wang Ke , Zhang Qin , Fu Qiang
Published: March 2007

So far, the reported content of multiwall carbon nanotubes (MWNTs) in polymer/MWNTs nanocomposites is usually above 0.1 wt %. In this article, we will report our work on the study of the morphology, crystallization, and mechanical properties of poly(ethylene terephthalate) (PET)/MWNTs nanocomposites prepared by in situ polymerization with very low content of MWNTs (from 0.01 to 0.2 wt %). Well‐dispersed MWNTs with a big network throughout PET matrix were observed by SEM. The very small amount of MWNTs displayed a great nucleating effect on the PET crystallization. The crystallization temperature was improved for 6.4°C by using only 0.01 wt % MWNTs. The decreased chain mobility of PET by adding MWNTs was evident by the formation of imperfect or smaller/thinner crystallites with low melting temperature. An increased storage modulus was also achieved for the nanohybirds with MWNT content less than 0.05 wt %. Our result indicates that using very low content MWNTs (less than 0.1 wt %) is a simple way to achieve good dispersion, yet with remarkable enhancement for polymer/MWNTs modification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3695–3701, 2007
Mechanochemical modification of silica with poly(1‐vinyl‐2‐pyrrolidone) by grinding in a stirred media mill
Authors: A. Voronov , A. Kohut , A. Synytska , W. Peukert
Published: March 2007

The polymerization of 1‐vinyl‐2‐pyrrolidone (VP) mechanochemically initiated by grinding silica was investigated in a wet stirred media mill. The polymerization itself proceeds from the silica grinding without any additional initiator. We have found that the amount of grafted polymer increases with an increase in total ground silica surface. The suspension of polymer‐modified silica nanoparticles showed high colloidal stability in water because of the appearance of grafted hydrophilic PVP on the surface during the reactive grinding. Because the nanoparticles SiO2‐graft‐PVP are biocompatible, the developed polymer nanocomposite material can be of particular interest for the performance of membranes and for the fabrication of biocompatible hydrogels with enhanced mechanical properties and porosity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3708–3714, 2007
Ceric ion‐induced graft copolymerization of acrylamide on cationic guar gum at low temperature
Authors: Wan Xiaofang , Li Youming , Wang Xiaojun , Wang Yanxia , Song Linlin
Published: March 2007

The solution polymerization of acrylamide (AM) on cationic guar gum (CGG) under nitrogen atmosphere using ceric ammonium sulfate (CAS) as the initiator has been realized. The effects of monomer concentration and reaction temperature on grafting conversion, grafting ratio, and grafting efficiency (GE) have been studied. The optimal conditions such as 1.3 mol of AM monomer and 2.2 × 10−4 mol of CAS have been adopted to produce grafted copolymer (CGG1‐g‐PAM) of high GE of more than 95% at 10°C. The rates of polymerization (Rp) and rates of graft copolymerization (Rg) are enhanced with increase in temperature (<35°C).The Rp is enhanced from 0.43 × 10−4 mol L−1 s−1 for GG‐g‐PAM to 2.53 × 10−4 mol L−1 s−1 for CGG1‐g‐PAM (CGG1, degree of substitute (DS) = 0.007), and Rg from 0.42 × 10−4 to 2.00 × 10−4 mol L−1 s−1 at 10°C. The apparent activation energy is decreased from 32.27 kJ mol−1 for GG‐g‐PAM to 8.09 kJ mol−1 for CGG1‐g‐PAM, which indicates CGG has higher reactivity than unmodified GG ranging from 10 to 50°C. Increase of DS of CGG will lead to slow improvement of the polymerization rates and a hypothetical mechanism is put forward. The grafted copolymer has been characterized by infrared spectroscopy, thermal analysis, and scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3715–3722, 2007
Effects of different coagulation conditions on polyacrylonitrile fibers wet spun in a system of dimethylsulphoxide and water
Authors: Wang Yan‐Xiang , Wang Cheng‐Guo , Yu Mei‐Jie
Published: March 2007

Polyacrylonitrile (PAN) precursors were prepared by the wet spinning way. The effects of the coagulation conditions, such as coagulation temperature, coagulation ratio, and coagulation concentration, are discussed in detail. While keeping the coagulation bath concentration constant, as the coagulation bath temperature increased, the cross section deviated less from a circular form, and the as‐spun fiber diameter decreased. Measurement to the rate of the boundary movement has been calculated depending on the coagulation rate. While keeping the coagulation bath temperature constant, high coagulation bath concentration can cause more coagulant to diffuse into the solution to the polymer precipitated consequently, which led to a faster coagulation rate. The as‐spun fiber from high coagulation concentration was compacted than those from low concentration. The character of the formed structure reflected the system mobility and capability to crystallize. Improvement in fiber density in the as‐spun fiber resulted in improvements in the tensile strength of the as‐spun fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3723–3729, 2007