bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Hydrocarbon Oils on the Physical Gelation of Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) Triblock Copolymers
Authors: Jin Kuk Kim  , Paglicawan Marissa A. , Sung Hyo Lee  , Balasubramanian Maridass
Published: March 2007

The physical gelation of triblock copolymer poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) in different hydrocarbon oils with different concentrations is studied in this article. The linear viscoelastic behavior, thermal transitions, swelling behavior, and gel properties on physical gelation are presented. The linear viscoelastic behavior is highly dependent on the copolymer concentration and type of oils. The degree of moduli responses of SEBS gels increase with higher gelation temperature, thereby indicating the longer lifetime of gel junctions. Small amounts of aromatic content in the hydrocarbon oil decreases the thermal stability of micelle formation of the gel and increases the compatibility of the solvent with copolymer, thereby resulting in low gelation temperature, lower moduli, as well as gel strength. With an increase in paraffinic content and molecular weight of hydrocarbon oil, the gelation temperature, moduli, and gel properties show improvement. Differential scanning calorimetric results show phase separation of soft segment and hard segment. The glass transition temperature (Tg) of soft ethylene—butylene (EB) midblock is not dependent on the triblock copolymer concentration nor on the type of oil, whereas the Tg of hard segment styrene endblock is highly dependent on triblock copolymer concentration and type of oil. The molecular weight and paraffinic hydrocarbon content of the oils are found to contribute to the stability of micelles and the incompatibility of hydrocarbon oil in SEBS triblock copolymer.
A Comparative Study of the Tensile Fatigue Behavior of Cotton—Polyester Blended Yarn by Cyclic Loading
Authors: Jeddi Ali A.A. , Nosraty H. , Taheri otaghsara M.R. , Karimi M.
Published: March 2007

The purpose of this investigation is to report the fatigue behavior of cotton and cotton—polyester blended yarn. A mechanism of fatigue behavior of staple yarn is suggested. The expressed mechanism of staple yarn fatigue is based on three stages: yarn decrimping, fiber slippage arising from inter fiber friction, and fiber elongation. The yarn decrimp mechanism occurs just at the initial stage of fatigue. The region of the sharp variations of the yarn viscoelastic properties up to nearly 1000 cycles of loading is attributed to the ability of the fiber to reorganize inside the yarn structure. Finally, the region of the steady variations of the viscoelastic properties of yarn seems to be due to fiber elongation. In this research, cotton and cotton—polyester blended yarn has been produced by rotor spinning. The general yarn characterization analysis has been performed, and then the viscoelastic properties of yarn have been analyzed by the Dynamic Mechanical Analyzer DMA 2980. The fatigue results reveal that the polyester fiber component has an important role in improving the fatigue resistance of the yarn to tensile cyclic loading. It has also been demonstrated that greater variations of yarn viscoelasticity are obtained with higher strain percent, so that at 1% strain the 100% cotton yarn reveals immediate failure. These results are interesting in view of the weaving process.
Arthroscopic Stabilization in Patients with an Inverted Pear Glenoid
Authors: Mologne Timothy S. , Provencher Matthew T. , Menzel Kyle A. , Vachon Tyler A. , Dewing Christopher B.
Published: March 2007

Background

Recent literature has demonstrated that the success rates of arthroscopic stabilization of glenohumeral instability deteriorate in patients with an anteroinferior glenoid bone deficiency, also known as the “inverted pear” glenoid.

Purpose

This study was conducted to assess the outcomes of arthroscopic stabilization for recurrent anterior shoulder instability in patients with a mean anteroinferior glenoid bone deficiency of 25% (range, 20%-30%).

Study Design

Cohort study; Level of evidence, 3.

Methods

Twenty-one of 23 patients (91% follow-up) undergoing arthroscopic stabilization surgery and noted to have a bony deficiency of the anteroinferior glenoid of 20% to 30% were reviewed at a mean follow-up of 34 months (range, 26-47). The mean age was 25 years (range, 20-34); 2 patients were female and 19 were male. All patients were treated with a primary anterior arthroscopic stabilization using a mean of 3.2 suture anchors (range, 3-4). Eleven patients had a bony Bankart that was incorporated into the repair; 10 had no bone fragment and were considered attritional bone loss. Outcomes were assessed using the Rowe score, the American Shoulder and Elbow Surgeons (ASES) Score, the Single Assessment Numeric Evaluation (SANE), and the Western Ontario Shoulder Instability (WOSI) Index. Findings of recurrent instability and dislocation events were documented.

Results

Two patients (9.5%) experienced symptoms of recurrent subluxation, and 1 (4.8%) sustained a recurrent dislocation that required revision open surgery. The mean postoperative outcomes scores were as follows SANE = 88.1 (range, 65-100; standard deviation [SD] 9.0); Rowe = 85.2 (range, 55-100; SD 14.1); ASES Score = 93.1 (range, 78-100; SD 5.3); and WOSI Index = 398 (82% of normal; range, 30-1175; SD 264). No patient with a bony fragment experienced a recurrent subluxation or dislocation, and mean outcomes scores for patients with a bony fragment were better than those with no bony fragment (P = .08). No patient required medical discharge from the military for his or her shoulder condition.

Conclusions

Arthroscopic stabilization for recurrent instability, even in the presence of a significant bony defect of the glenoid, can yield a stable shoulder; however, outcomes are not as predictable especially in attritional bone loss cases. Longer-term follow-up is needed to see if these results hold up over time.
On Philosophical Style
Authors: Lehtinen Virpi
Published: March 2007

Irigaray and Le Dœuff diagnose the problem of woman and philosophy in terms of love. The differing solutions to the problem can be found in their styles. Irigaray's style is loving and dialogic, transforming the inherent structure of love and reminding us of the traditional feminine position defined by men. Le Dœuff's style is critical and pluralistic and relates to her perception of the feminine way of philosophical writing. These styles take into account the undervaluation of the feminine in the apparently `neutral' practices of philosophizing and surpass the traditional or unreflected notions of the feminine style. Ultimately, the consciously `subjective' styles, with the inherent aims of self-reflectivity and openness for other persons and texts, prove necessary when striving for truth and objectivity. Thus, Le Dœuff and Irigaray question the standard notion of philosophical style as neutral `non-style'.
Audit Qualifications of Income‐Decreasing Accounting Choices*
Authors: Hodge Frank D. , Martin Roger D. , Pratt Jamie H.
Published: March 2007

In this study we conduct an experiment to examine how qualifying an income‐decreasing accounting change in years of strong financial performance affects financial report users' assessments of strategic reporting, current financial performance, and future financial performance (performance over the next three years). We find that without the qualification, users viewed the income‐decreasing accounting change as relatively nonstrategic and that user assessments of current and future performance were not different. In the presence of the qualification, users believed that the accounting change was relatively strategic, and they discounted the income effect of the accounting change. We find further that their assessments of future performance were below their assessments of current performance but no different from the assessments of future performance in the absence of the qualification. Although our findings suggest that audit qualifications encourage users to be skeptical of income‐decreasing accounting changes, we find no evidence that they impose negative consequences on management in terms of lower assessments of financial performance.
The Evolution of the Standard Unqualified Auditor's Report in Canada / L'ÉVOLUTION DU RAPPORT TYPE DU VÉRIFICATEUR AU CANADA
Authors: MAINGOT MICHAEL
Published: March 2007

This study examines the historical development of the auditor's report in Canada. The auditor's report has been significantly influenced by British and U.S. legislation and practices. The English Joint Stock Companies Act of 1844 required compulsory audits and the British audit report was introduced in North America shortly after the introduction of this Act. The legislature prescribed an audit but it did not determine the form and content of the auditor's report; these were left to the individual practitioner. The British influence was strong in Canada up to the 1930s. However, from this time onward, the U.S. influence began to grow. The impact of the landmark case of Ultramares v. Touche on third‐party liability and consequent change in the auditor's report is analyzed. The paper uses institutional theory to explore reasons for the similarities of the auditor's report under British influence and under American influence. Specifically, the paper examines how the mechanisms of mimetic, coercive, and normative isomorphism led to institutional change in the accounting profession as organizations adapted their auditors' reports to achieve greater legitimacy.
The Sarbanes‐Oxley Act of 2002 and Capital‐Market Behavior: Early Evidence*
Authors: Jain Pankaj K. , Rezaee Zabihollah
Published: March 2007

The Sarbanes‐Oxley Act of 2002 (“the Act”) was enacted in response to numerous corporate and accounting scandals. It aims to reinforce corporate accountability and professional responsibility in order to restore investor confidence in corporate America. This study examines the capital‐market reaction to the Act and finds a positive (negative) abnormal return at the time of several legislative events that increased (decreased) the likelihood of the passage of the Act. We interpret this finding as evidence supporting the notion that the Act is wealth‐increasing in the sense that its induced benefits significantly outweigh its imposed compliance costs. We also find that the market reaction is more positive for firms that are more compliant with the provisions of the Act prior to its enactment.
Cherry Picking, Disclosure Quality, and Comprehensive Income Reporting Choices: The Case of Property‐Liability Insurers*
Authors: Lee Yen‐Jung , Petroni Kathy R. , Shen Min
Published: March 2007

Statement of Financial Accounting Standards No. 130: Reporting Comprehensive Incomeencourages enterprises to report comprehensive income on a performance statement rather than on a statement of equity. We investigate the reporting decisions of 82 publicly traded property‐liability insurers that are fairly evenly split in their choice. Our results demonstrate that insurers with a tendency to manage earnings through realized securities' gains and losses (that is, cherry pickers), as well as insurers with a reputation for poor disclosure quality, are more likely to report comprehensive income in a statement of equity. Apparently, these insurers face the highest cost of transparency. We do not find a relation between the reporting decision and the volatility of comprehensive income relative to the volatility of net income. Our findings that insurers' comprehensive income reporting choices are a reflection of their proclivity toward cherry picking as well as their level of disclosure quality should be of interest to standard‐setters because of the controversy over standard‐setters' preference for mandating all firms to report comprehensive income in a performance statement.
Coordinating Effort under Team‐Based and Individual Incentives: An Experimental Analysis*
Authors: RANKIN FREDERICK W.
Published: March 2007

This paper explores the behavior of workers in an environment where it is efficient to engage in the mutual exchange of help. Experimental data show that output and workers' payoffs are greater under team‐based incentives than under individual incentives in an environment where coordination is difficult. However, when the environment is more conducive to coordination (that is, a setting where agents interact repeatedly), output and payoffs are greater under individual incentives. Manipulation of the amount of mutually observable information provides evidence that team‐based incentives, relative to individual incentives, create a more difficult coordination problem for workers and that cooperation requires a richer informational environment.
How Has Regulation FD Affected the Operations of Financial Analysts?*
Authors: Mohanram Partha S. , Sunder Shyam V.
Published: March 2007

In this paper, we analyze how financial analysts generate information, make decisions about firm coverage, and try to maintain their forecasting accuracy after the passage of Regulation Fair Disclosure (“Reg FD”). Using the model developed by Barron, Kim, Lim, and Stevens 1998, we find that analysts are investing more effort in idiosyncratic information discovery. In order to do this, individual analysts appear to be reducing coverage for well‐followed firms while increasing coverage of firms that were less followed prior to Reg FD. Analysts who had preferential links with firms that they covered, such as analysts from large brokerage houses, tend to have greater forecast accuracy in the pre‐FD period. However, these analysts are unable to sustain their forecasting superiority in the post‐FD period, which suggests that there has been a leveling of the information playing field among analysts. Overall, our results reflect a trend toward greater reliance on idiosyncratic information discovery on part of the financial analysts.
Pricing of Initial Audit Engagements by Large and Small Audit Firms*
Authors: Ghosh Aloke , Lustgarten Steven
Published: March 2007

We investigate the extent to which auditors of U.S. companies reduce fees on initial audit engagements (“fee discounting”). We hypothesize that rivalries among sellers, in terms of client turnover and price competition, are more intense among small audit firms. The data support this hypothesis. New clients account for 34 percent of all clients for small audit firms, but only 9 percent of all clients for large audit firms. We theorize that differences in client turnover rates between large and small audit firms can be explained by the market structure of the audit industry, which consists of an oligopolistic segment dominated by a few large audit firms and an atomistic segment composed of many small audit firms. We further hypothesize and confirm that fee discounting is more extensive in the atomistic sector, and our results confirm this hypothesis. Our analysis of audit fee changes indicates that clients who switch auditors within the atomistic sector receive on average a discount of 24 percent over the prior auditor's fee. However, clients who switch auditors within the oligopolistic sector receive on average a discount of only 4 percent. Given that price competition is known to be less intense in oligopolistic markets than in atomistic markets, we believe that market structure theory can explain why fee discounting is lower when larger audit firms compete for clients.
Learning by Doing and Audit Quality*
Authors: Beck Paul J. , Wu Martin G. H.
Published: March 2007

In this study, we present a nonstrategic, dynamic Bayesian model in which auditors' learning on the job and their choice of professional services jointly affect audit quality. While performing audits over time, auditors accumulate client‐specific knowledge so that their posterior beliefs about clients are updated and become more precise (that is, precision is our surrogate for audit quality) — what we call the learning effect. In addition, auditors can enrich their knowledge accumulation by performing nonaudit services (NAS) that, in fact, may influence clients' managerial decisions — what we call the business advisory effect. This advisory effect permits auditors to anticipate and to learn about changes in clients' business models, which in turn improves their advisory capacity. These dual “learning” and “advisory” effects are interdependent and mutually reinforcing.

The advisory effect of NAS may increase or reduce auditors' engagement risk. We show that large professional fees can induce auditors to provide NAS that increase engagement risk and diminish audit quality. However, when NAS reduce engagement risk and increase audit quality, auditors may provide NAS without charging clients. The feature that distinguishes our study — the interdependence between the learning and advisory effects — provides new insight into the trade‐off between audit fees and audit quality. Consequently, our analysis helps explain why the scope of the audit has evolved over time and why the boundaries between audit and NAS are constantly shifting. A recent example of such a shift is that the Sarbanes‐Oxley Act adds control attestation to audits for public companies traded in U.S. markets.
Accounting Information and CEO Compensation: The Role of Cash Flow from Operations in the Presence of Earnings*
Authors: Nwaeze Emeka T. , Yang Simon S. M. , Yin Q. Jennifer
Published: March 2007

We examine the role of cash flow from operations (CFO) in chief executive officer (CEO) cash compensation. We predict that CFO is contract‐relevant in the presence of earnings, and more so when (1) the quality of earnings relative to the quality of CFO as a measure of performance is low and (2) the need for CFO as a financing source is high. Our analysis is motivated principally by normative arguments and anecdotes from financial disclosures linking CFO to managerial effort and contracts, notwithstanding the traditional role of earnings in performance measurement. We find that the weight of CFO in the compensation model is positive and significant in the presence of earnings and stock returns. We also find that the relative quality of CFO compared with that of earnings has a positive (negative) impact on the weight of CFO (earnings). We further find that the relative weight of CFO is enhanced substantially when enterprise activities crucially depend on internally generated cash flow. These findings are unaltered when we include CEO age, firm size, and risk in the model and allow the coefficients to vary across industries.
The Persistence of the Accruals Anomaly*
Authors: Lev Baruch , Nissim Doron
Published: March 2007

The accruals anomaly — the negative relationship between accounting accruals and subsequent stock returns — has been well documented in the academic and practitioner literatures for almost a decade. To the extent that this anomaly represents market inefficiency, one would expect sophisticated investors to learn about it and arbitrage the anomaly away. We show that the accruals anomaly still persists and, even more strikingly, its magnitude has not declined over time. How can this be explained? We show that the accruals anomaly is recognized and, indeed, exploited by certain active institutional investors, but the magnitude of this accruals‐related trading is rather small. By and large, institutions shy away from extreme‐accruals firms because their attributes, such as small size, low profitability, and high risk stand in stark contrast to those preferred by most institutions. Individual investors are also, by and large, unable to profit from trading on accruals information due to the high information and transaction costs associated with implementing a consistently profitable accruals strategy. Consequently, the accruals anomaly persists and will probably endure.
The Public Policy Debate on Investors' Need for Disclosure Regulation: Accounting Historians' Help Wanted?*/ LE DÉBAT PUBLIC SUR LES BESOINS DES INVESTISSEURS EN MATIÈRE DE RÉGLEMENTATION DE L'INFORMATION: FAUT‐IL L'AIDE DES HISTORIENS DE LA COMPTABILITÉ?
Authors: GÉLINAS PATRICE , BAILLARGEON LISA
Published: March 2007

This paper explores how research in accounting history can contribute to the important public policy debate regarding investors' need for disclosure regulation. Accounting, finance, and economics researchers and practitioners argue for, as well as against, disclosure regulation. The debate remains theoretical, however, because empirical studies are virtually nonexistent. This paper reviews five contexts in which accounting historians can begin a search for empirical insights concerning the costs, benefits, externalities, and effects on stakeholders of disclosure regulation. The paper's investigation of the accounting history literature suggests that accounting historians could improve the quality of the debate and help accommodate broader interests or alternative solutions to financial crises.
Modeling Goodwill for Banks: A Residual Income Approach with Empirical Tests*
Authors: Begley Joy , Chamberlain Sandra L. , Li Yinghua
Published: March 2007

This paper uses the residual income valuation technique outlined in Feltham and Ohlson 1996 to examine the relation between stock valuations and accounting numbers for a prototypical banking firm. Prior work of this nature typically assumes a manufacturing setting. This paper contributes to the prior research by clarifying how the approach can be extended to settings where value is created from financial assets and liabilities. Key elements of our model include allowing banks to generate positive net present value from either lending or borrowing activities, and allowing for accounting policy to affect valuation through the loan loss allowance.

We validate our model using archival data analysis, and interpret coefficients in light of our modeling assumptions. These results suggest that banks create value more from deposit‐taking activities than from lending activities. Vuong tests confirm that our model outperforms adaptations of the unbiased accounting model of Ohlson 1995 and adaptations of the base model proposed by Beaver, Eger, Ryan, and Wolfson 1989. However, our model is outperformed by the popular net income‐book value model used in many empirical studies, and we can formally reject one of our key modeling assumptions. These tests of our model suggest future avenues for improving upon the theoretical analysis.
Expectations Management and Beatable Targets: How Do Analysts React to Explicit Earnings Guidance?*
Authors: Cotter Julie , Tuna Irem , Wysocki Peter D.
Published: March 2007

This study investigates security analysts' reactions to public management guidance and assesses whether managers successfully guide analysts toward beatable earnings targets. We use a panel data set between 1995 and 2001 to examine the fiscal‐quarter‐specific determinants of management guidance and the timing, extent, and outcomes of analysts' reactions to this guidance. We find that management guidance is more likely when analysts' initial forecasts are optimistic, and, after controlling for the level of this optimism, when analysts' forecast dispersion is low. Analysts quickly react to management guidance and are more likely to issue final meetable or beatable earnings targets when management provides public guidance. Our evidence suggests that public management guidance plays an important role in leading analysts toward achievable earnings targets.
Fixed Cost Magnitude, Fixed Cost Reporting Format, and Competitive Pricing Decisions: Some Experimental Evidence*
Authors: BUCHHEIT STEVE
Published: March 2007

Although neoclassical economic theory predicts that fixed cost magnitude and fixed cost reporting format will not influence short‐term pricing decisions, these factors systematically affected pricing decisions in a duopoly experiment. Increasing fixed cost magnitude (a pure sunk cost in this study) across experimental conditions caused participants to first lower, then raise, competitive prices. Consistent with the psychological phenomenon of loss aversion, this change in pricing behavior reduced the frequency of reported losses. This study further reveals that the accounting format for reporting fixed costs influenced pricing behavior. Specifically, participants receiving capacity costing feedback reports established increasingly lower selling prices relative to the prices established by participants receiving contribution margin feedback reports. Given that a very simple cosmetic reporting manipulation produced increasingly significant competitive pricing differences in a market setting, this study provides evidence that functional fixation is not necessarily eliminated by market forces.
Corporate Investment Incentives and Accounting‐Based Debt Covenants*
Authors: Douglas Alan V. S.
Published: March 2007

This paper studies the conditions under which accounting‐based debt covenants increase firm value in a setting that incorporates the conflicting incentives of shareholders, bondholders, and managers. We construct a model in which debt is needed to discipline managerial investment decisions despite endogenous compensation contracts. We show that accounting covenants increase value when (1) debt serves as a credible commitment to penalize poor investment decisions; (2) the firm faces other (exogenous) sources of uncertainty that can make debt risky despite good investment decisions; and (3) accounting information serves as a contractible proxy for firm's economic performance. In these circumstances, accounting covenants ensure that shareholders do not offer compensation schemes that would encourage bondholder wealth expropriation when the debt becomes risky. A covenant specifying a required level of accounting performance provides additional bondholder power when performance is low. An accounting‐based dividend covenant allows a disbursement to maintain investment incentives when performance is high without allowing dividend‐based expropriation. The optimal covenants depend on the reliability of accounting information, and the interaction between accounting performance and the different incentive conflicts provides new insight into the empirical literature on accounting‐based covenants.
THE USE OF PHOTQGBRPHY FOR THE RECOVERY OF NORTHWEST COAST PAINTED DESIGNS
Authors: Cotic Mila
Published: March 2007

At the Museum of Anthropology in Vancouver, British Columbia, experimental photographic techniques are being used to reveal early Northwest Coast designs found on traditional, painted artifacts. These techniques are important i n making early Northwest Coast designs accessible for study, and their continuation would make possible the recovery of Northwest Coast painted designs on artifacts from museums around the world.
Large-scale interface shear testing of sandbag dyke materials
Authors: Krahn T. , Blatz J. , Alfaro M. , Bathurst R. J.
Published: March 2007

This paper presents results of large-scale direct shear testing of six interfaces with materials used to construct sandbag dykes for flood protection structures. Two additional test series using intact sandbags were also conducted to examine the influence of sandbag-to-sandbag interaction in typical stacked sandbag dyke construction and sandbag-to-sod (grass) contact representing the interface condition at the dyke foundation. The interface test results are summarised using Mohr–Coulomb shear strength parameters and interface shear stiffness parameters. The data presented in this paper are necessary for stability analyses of instrumented and monitored sandbag dyke structures that are currently under way as part of the development of a new guidance document for the design of sandbag dykes for temporary flood protection works in Canada.
Aluminum alloy welding by using a high power direct diode laser
Authors: Abe N. , Tsukamoto M. , Maeda K. , Namba K. , Morimoto J.
Published: March 2007

Aluminum alloys are the focus of increasing attention from the automobile industry because of their light weight, high formability, and easy recyclability. In this report, a 4 kW high power direct diode laser was used to examine the weldability of aluminum alloys of AA5022 and AA6016. A heat conduction welding type bead shape was produced with a very smooth bead surface. Full penetration butt welding was possible up to a welding speed of 12 m/min for 1 mm thick AA5022 and 6 m/min for 1 mm thick AA6016. Welding phenomena were observed with a high speed video camera. Very quiet welding phenomena were observed, with no spattering or laser plasma formation.
Study of laser assisted decontamination of commonly used clad surfaces
Authors: Nilaya J. P. , Kumar Aniruddha , Raote P. , Sai Prasad M. B. , Biswas D. J.
Published: March 2007

The decontamination factor, defined as the ratio of initial to residual activity, is studied as a function of laser fluence for three kinds of clad surfaces viz., plain zircaloy, autoclaved zircaloy, and stainless steel with cesium as the simulated contamination. It has been found that the decontamination factor exhibits a maximal behavior with the laser fluence and its maximum value occurs at different laser fluences in the three cases. The maximal behavior is attributed to reduced coupling of energy from the laser beam to the substrate due to the initiation of surface-assisted optical breakdown. The results obtained in the experiment carried out in helium environment qualitatively support this explanation.
Threshold powers and delays for igniting propane and butane-air mixtures by cw laser-heated small particles
Authors: Dubaniewicz Thomas H.
Published: March 2007

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approximately proportional to beam diameter for beam diameters from 0.1 to 2.0 mm. Results suggest that relatively powerful beams may be used in these atmospheres without causing ignition, provided the beam diameter is controlled. Threshold ignition delay times using 9/125 and 62.5/125 μm fibers were approximately proportional to the inverse square of the laser power. Ignition delays were about 45 ms or longer for laser powers up to 800 mW. Preproduction samples of a commercial optical fuse prevented ignitions under selected test conditions. A self-healing effect was observed for one sample. Comparisons are made with the results of other researchers.
Fabrication of waveguides in Foturan by femtosecond laser
Authors: Li Z. L. , Low D. K. Y. , Ho M. K. , Lim G. C. , Moh K. J.
Published: March 2007

We report two methods of fabricating waveguides in photosensitive Ag+ doped Foturan glass by femtosecond laser writing and subsequent annealing. The first method involves writing at laser energies higher than the optical breakdown threshold, directly resulting in microstructural changes and a refractive index increase. In contrast, the laser energy used in the second method was much lower than the threshold for optical breakdown. Subsequent thermal annealing at 500 °C after this writing process causes Ag nanoparticles to precipitate in the laser written trace and a corresponding increase in the refractive index. The effect of Ag nanoparticles population on the guiding characteristics of the written waveguides is addressed. We found that there is an optimum population of Ag nanoparticles in a waveguide. Propagation losses increase at above this population level due to high absorption/scattering, while a population level below the optimum is indicative of minimal index change and hence providing poor confinement.
Cutaneous sensation threshold for 3.8 μm radiation from a short duration pulsed laser on the calves of human subjects: A pilot study
Authors: Johnson Thomas E. , Roy Michael J.
Published: March 2007

The objective of this study was to determine the threshold for sensing a 3.8 μm laser on the skin. The identification of the skin sensation threshold for invisible lasers is useful in providing scientific guidance to the safety community regarding accidental skin exposures. Knowledge of the level of sensation of lasers might be used to show that sensation may not coincide with the exposure limits, and could in fact be orders of magnitude greater than limits. This type of information can be used in conjunction with studies performed on animals to help better define the minimum radiant exposure required to elicit minor skin changes. Future standards for skin exposure could potentially be based on sensation thresholds, if the difference between gross morphologic skin changes and sensation provide a sufficient safety margin. This study involved exposing ten volunteers on their calf to incrementally increasing energy from single 3.8 μm, 4 μs pulses with a spot size of approximately 4 cm2. The laser pulse was sensed by the subjects between an average of 2.3 and 3.1 J/cm2, a level significantly above the maximum permissible exposure, but below which significant gross morphologic changes occur to the skin. Exposures greater than 2.4 J/cm2 resulted in desiccation with concomitant separation of the superficial layer of epidermis in all subjects. Mild erythema presented within five minutes at exposures greater than 6.4 J/cm2, resolving within 72 h.
Dendrochronological Studies of Wood from Mediaeval Mines of Polymetallic Ores in Lower Silesia (Sw Poland)
Authors: Szychowska-Krąpiec Elżbieta
Published: March 2007

The paper presents results of dendrochronological dating of wood encountered in abandoned mines in the eastern part of Lower Silesia. The research was carried out in gold mines in Złoty Stok, Głuchołazy, and Zlate Hory, a polymetallic-ore mine in Marcinków as well as old mines in the Sowie Mts: the Silberloch adit, an adit on the hillside of Mała Sowa, a graphite mine, and the silver and lead mine Augusta. Altogether 69 samples were taken from timbers of coniferous tree species: Pinus sylvestris, Abies alba, Picea abies and Larix decidua. The oldest wood, from the turn of the fifteenth and sixteenth centuries was encountered in the gold mines in Zlate Hory and Głuchołazy. In the gold mine in Złoty Stok, graphite mine in Sowie Mts and in Marcinków there was identified wood from the seventeenth and eighteenth centuries. Generally, timbers from the nineteenth century were prevailing, and in three cases there was even encountered relatively young twentieth-century wood in the gold mine in Złoty Stok and in the Silberloch adit. The analyses carried out were only preliminary. Broader, interdisciplinary investigations, including dendrochronology, archaeology, geology, mining, and palaeobotany, would substantially contribute for learning the history of the mining in the whole region.
Synthesis and evaluation of anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation properties of ibuprofen derivatives
Authors: Amir Mohammad , Kumar Shikha
Published: March 2007

Synthesis and evaluation of anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation properties of ibuprofen derivatives

In order to reduce the ulcerogenic effect of ibuprofen, its carboxylic group has been converted into 5-membered heterocyclic rings. Various 1,3,4-oxadiazoles (3-8, 16-21), 1,2,4-triazoles (22-27), 1,3,4-thiadiazoles (28-30), and 1,2,4-triazine (9) derivatives of ibuprofen were prepared by cyclization of 2-(4-i-butylphenyl) propionic acid hydrazide (2) and N1-[2-(4-i-butylphenyl) propionyl]-N4-alkyl/arylthiosemicarbazides (10-15) under various reaction conditions. The cyclized derivatives were screened for their anti-inflammatory activity by the carrageenan induced rat paw edema method and showed 50 to 86% inhibition, whereas the standard drug ibuprofen showed 92% inhibition at the same oral dose. Five compounds, 7, 16, 18, 22 and 30 that showed more than 80% anti-inflammatory activity were selected to study their analgesic, ulcerogenic and lipid peroxidation activities. All the tested compounds showed a significant reduction in ulcerogenic activity compared to ibuprofen through the severity index 0.5 to 0.8, vs. ibuprofen 1.8. The compounds, that showed less ulcerogenic effect also produced less malondialdehyde content in gastric mucosa, which is one of the end products of lipid peroxidation. The results of biological studies showed that oxadiazole derivative 16 as the lead molecule with maximum anti-inflammatory, analgesic and minimum ulcerogenic and lipid peroxidation activities.
Influence of process variables on release properties of paracetamol tablets
Authors: Alebiowu Gbenga , Itiola Oludele
Published: March 2007

Influence of process variables on release properties of paracetamol tablets

A 23 factorial experimental design has been used to quantitatively study individual and interaction effects of the nature of binder (N), binder concentration (c) and relative density of tablet (d) on the disintegration time (DT) and dissolution times, t1, t50 and t90, of paracetamol tablet formulations. The factorial design was also used to study the quantitative effects of pregelatinization of starch binders on these parameters, i.e., N, c and d. In general, the most common ranking of the individual effects on DT, t1, t50 and t90 for native/native, pregelatinized/pregelatinized and native/pregelatinized starch binder formulations was c > d > N. For interaction effects, the most common ranking was N-c > c-d > N-d for all formulations. The results generally showed that c can considerably affect DT, t1, t50 and t90 of the tablets.
Rapid titrimetric and spectrophotometric methods for salbutamol sulphate in pharmaceuticals using N-bromosuccinimide
Authors: Basavaiah Kanakapura , Somashekar Bankavadi , Ramakrishna Veeraiah
Published: March 2007

Rapid titrimetric and spectrophotometric methods for salbutamol sulphate in pharmaceuticals using N-bromosuccinimide

One titrimetric and two spectrophotometric methods which are simple, sensitive and rapid are described for the assay of salbutamol sulphate (SBS) in bulk drug and in tablet dosage forms using N-bromosuccinimide (NBS) and two dyes, rhodamine-B and methylene blue, as reagents. In titrimetry, aqueous solution of salbutamol sulphate is treated with a measured excess of NBS in acetic acid medium and after the oxidation of SBS is complete, the unreacted oxidant is determined iodometrically. Spectrophotometric methods entail addition of a known excess of NBS in acid medium followed by the determination of residual oxidant by reacting with a fixed amount of either rhodamine B and measuring the absorbance at 555 nm (method A) or methylene blue and measuring the absorbance at 665 nm (method B). In all methods, the amount of NBS reacting corresponds to the amount of SBS content. Titrimetric method is applicable over 1.74 x 10-4 - 8.68 x 10-4 mol L-1 range and the reaction stoichiometry is found to be 1:6 (SBS:NBS). In spectrophotometric methods, the absorbance is found to increase linearly with the concentration of SBS, which is corroborated by the correlation of coefficients of 0.9993 and 0.9988 for method A and method B, respectively. The systems obey Beer's law for 0.25-1.75 μg mL-1 (method A) and 0.5-5.0 μg mL-1 (method B). The calculated apparent molar absorptivity values were found to be 2.10 x 105 and 6.16 x 104 L mol-1 cm-1, for method A and method B, respectively. The limits of detection and quantification are also reported for both spectrophotometric methods. Intraday and inter-day precision and accuracy for the developed methods were evaluated. The methods were successfully applied to the assay of SBS in tablet and capsule formulations and the results were statistically compared with those of a reference method. No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by recovery experiments via the standard-addition technique.
Liquisolid technique as a tool for enhancement of poorly water-soluble drugs and evaluation of their physicochemical properties
Authors: Javadzadeh Yousef , Siahi Mohammad , Asnaashari Solmaz , Nokhodchi Ali
Published: March 2007

Liquisolid technique as a tool for enhancement of poorly water-soluble drugs and evaluation of their physicochemical properties

The potential of liquisolid systems to improve the dissolution properties of a water-insoluble agent (indomethacin) was investigated. In this study, different formulations of liquisolid tablets using different co-solvents (non-volatile solvents) were prepared and the effect of aging on the dissolution behaviour of indomethacin liquisolid compacts was investigated. To evaluate any interaction between indomethacin and the other components in liquisolid formulations, X-ray powder diffraction (XPD) and differential scanning calorimetry (DSC) were used. Dissolution test was carried out at two different pH, 1.2 and 7.2, to simulate the stomach or intestine fluid, respectively. The results showed that liquisolid formulations exhibited significantly higher drug dissolution rates at pH 1.2 and 7.2 compared to compacts prepared by the direct compression technique. The enhanced rate of indomethacin dissolution from liquisolid tablets was probably due to an increase in wetting properties and surface area of drug particles available for dissolution. In order to investigate the effect of aging on the hardness and dissolution rate of liquisolid compacts, the formulations were stored at 25 °C/75% relative humidity for a period of 12 months. The results showed that aging had no significant effect on dissolution profiles of liquisolid tablets. Liquisolid compacts containing propylene glycol as vehicle produced higher dissolution rates in comparison with liquisolid compacts containing PEG 400 or Tween 80 of the same concentration. The DSC and XPD results showed no changes in crystallinity of the drug and interaction between indomethacin and excipients (Avicel and silica) during the process.
Der σ‐CAM‐Mechanismus: σ‐Komplexe als Schlüssel der σ‐Bindungsmetathese bei späten Übergangsmetallen
Authors: Perutz Robin N. , Sabo‐Etienne Sylviane
Published: March 2007

Komplexe, in denen eine σ‐H‐E‐Bindung (E = H, B, Si, C) als ein Zweielektronendonor zum Metall agiert, werden als σ‐Komplexe bezeichnet. Hinweise darauf, dass σ‐Liganden ohne Wechsel der Oxidationsstufe ineinander umgewandelt werden können, finden sich bei C‐H‐Aktivierungsreaktionen mit Isotopenaustausch und in dynamischen Umlagerungen von σ‐Komplexen (siehe Vortitel). Über diese beiden Reaktionswege können Metathesen von M‐E‐Bindungen an späten Übergangsmetallen ablaufen, und wir nennen diesen Prozess σ‐Komplex‐vermittelte Metathese oder σ‐CAM. Die Reaktion unterscheidet sich mechanistisch von den bekannten σ‐Bindungsmetathesen (die typisch für d0‐Metalle sind und ohne Intermediat ablaufen) und von den oxidativen Additionen/reduktiven Eliminierungen (bei denen Intermediate mit wechselnden Oxidationsstufen auftreten und die manchmal unter Beteiligung von σ‐Komplexen ablaufen). Es gibt Beispiele für σ‐CAM‐Mechanismen in der Katalyse, insbesondere in der Alkanborylierung und beim Isotopenaustausch von Alkanen. σ‐CAM‐Mechanismen können außerdem auch bei Silylierungen und der Alkenhydrierung auftreten.
Synthesis and characterization of polyacrylamide‐grafted coconut coir pith having carboxylate functional group and adsorption ability for heavy metal ions
Authors: Anirudhan T. S. , Unnithan M. R. , Divya L. , Senan P.
Published: March 2007

The present investigation was undertaken to evaluate the effectiveness of a new adsorbent prepared from coconut coir pith (CP), a coir industry‐based lignocellulosic residue in removing metal ions from aqueous solutions. The adsorbent (PGCP‐COOH) having a carboxylate functional group at the chain end was prepared by grafting polyacrylamide onto CP using potassium peroxydisulphate as an initiator and in the presence of N,N′‐methylenebisacrylamide as a crosslinking agent. The adsorbent was characterized by infrared (IR) spectroscopy, thermogravimetry (TG), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and potentiometric titration. The adsorbent exhibits very high adsorption potential for the removal of Pb(II), Hg(II), and Cd(II) ions from aqueous solutions. The optimum pH range for metal ion removal was found to be 6.0–8.0. The adsorption process follows a pseudo‐second‐order kinetic model. The adsorption capacities for Hg(II), Pb(II), and Cd(II) calculated using the Langmuir isotherm equation were 254.52, 189.49, and 63.72 mg g−1, respectively. Adsorption isotherm experiments were also conducted for comparison with a commercial carboxylate form cation exchanger. Different industry wastewater samples were treated by the PGCP‐COOH to demonstrate its efficiency in removing heavy metals from wastewater. The reusability of the PGCP‐COOH was also demonstrated using 0.2M HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3670–3681, 2007
Miscibility and properties of semi‐interpenetrating polymer networks based on polyurethane and nitroguar gum
Authors: Huang Yihong , Fan Qingchun , Xiao Chaobo
Published: March 2007

Films from castor oil‐based polyurethane (PU) prepolymer and nitroguar gum (NGG) with different contents (10–70 wt %) were prepared through solution casting method. The networks of PU crosslinked with 1,4‐butanediol were interpenetrated by linear NGG to form semi‐interpenetrating polymer networks (semi‐IPNs) in the blend films. The miscibility, morphology, and properties of the semi‐IPNs coded as PUNG films were investigated with Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, wide‐angle X‐ray diffraction, density measurement, ultraviolet spectroscopy, thermogravimetric analysis, tensile, and solvent‐resistance testing. The results revealed that the semi‐IPNs films have good miscibility over the entire composition ratio of PU to NGG under study. The occurrence of hydrogen‐bonding interaction between PU and NGG played a key role in improvement of the material performance. Compared with the pure PU film, the PUNG films exhibited higher values of tensile strength (11.7–28.4 MPa). Meanwhile, incorporating NGG into the PU networks led to an improvement of thermal stability and better solvent‐resistance of the resulting materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 4068–4079, 2007
Hydraulic permeability of a hydrogel‐based contact lens membrane for low flow rates
Authors: Pishko Gregory L. , Lee Sung‐Jin , Wanakule Prinda , Sarntinoranont Malisa
Published: March 2007

Hydrogels, widely used for contact lenses, are a class of materials that consists of both fluid and solid components. The aqueous fluid phase is supported by a solid polymer matrix. In this study, we characterize the water transport characteristics of an Etafilcon‐A (copolymer of 2‐hydroxyethyl methacrylate and methacrylic acid) membrane. A flow rate‐controlled permeameter consisting of a syringe pump, membrane holder, pressure transducer, and tubing was developed and used to measure the pressure drop across a flat membrane (average thickness ∼ 686 μm ± 40). The relation between velocity and pressure drop was measured. These data were fit to rigid media and biphasic models of 1‐D flow to determine hydraulic permeability, k = 1.80 × 10−14 m4/N s. The results provide insight into the fluid flow properties of this hydrogel under low flow and low pressure conditions (<3 kPa). Physiological implications of these measured parameters on flow and deformation across the lens due to blinking are discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3730–3735, 2007