bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethical Guidance and Constraint Under the Sarbanes-Oxley Act of 2002
Authors: Orin Richard M.
Published: July 2017

This article discusses two key features of the Sarbanes-Oxley Act, which was enacted in 2002 to restore integrity and public confidence to the financial markets. The law was passed in response to the horrendous corporate disasters that had occurred, including Enron, Worldcom, Adelphia, and Tyco. The implementation of effective business ethics became essential and the new law required the publication of corporate codes of ethics. It did not mandate their content. This paper suggests specific sections for inclusion in the general guidelines to encompass the ethical dimensions of the Act. It analyzes the compliance by the corporations in their public filings since Sarbanes-Oxley became law. The revelation of the size of the audit and accounting fees paid to Arthur Andersen by Enron and similar fees paid in other current financial debacles lead to another key requirement of Sarbanes-Oxley: mandatory auditor rotation. Here, however, Sarbanes-Oxley did not go far enough. The law required rotation only of the lead auditor within a firm. This paper submits that it should have required rotation of audit firms instead. The positions of the public companies, the American Institute of Certified Public Accountants, the Government Accountability Office, and accounting journals are explored as to the rotation of auditor firms regarding audit-partner rotation within a firm. The paper concludes that Sarbanes-Oxley should be expanded to require audit-firm rotation. This expansion is necessary to reinforce the independence of the public accountant, both in fact and appearance, and to restore competition within the accounting profession, which will benefit the investing public. It is up to the Security and Exchange Commission and the Public Company Accounting Oversight Board and, ultimately, Congress to make this expansion a reality.
Information Conveyed in Hiring Announcements of Senior Executives Overseeing Enterprise-Wide Risk Management Processes
Authors: Beasley Mark , Pagach Don , Warr Richard
Published: July 2017

Enterprise risk management (ERM) is the process of analyzing the portfolio of risks facing the enterprise to ensure that the combined effect of such risks is within an acceptable tolerance. While more firms are adopting ERM, little academic research exists about the costs and benefits of ERM. Proponents of ERM claim that ERM is designed to enhance shareholder value; however, portfolio theory suggests that costly ERM implementation would be unwelcome by shareholders who can use less costly diversification to eliminate idiosyncratic risk. This study examines equity market reactions to announcements of appointments of senior executive officers overseeing the enterprise's risk management processes. Based on a sample of 120 announcements from 1992-2003, we find that the univariate average two-day market response is not significant, suggesting that a general definitive statement about the benefit or cost of implementing ERM is not possible. However, our multiple regression analysis reveals that there are significant relations between the magnitude of equity market returns and certain firm specific characteristics. For nonfinancial firms, announcement period returns are positively associated with firm size and the volatility of prior periods' reported earnings and negatively associated with leverage and the extent of cash on hand relative to liabilities. For financial firms, however, there are fewer statistical associations between announcement returns and firm characteristics. These results suggest that the costs and benefits of ERM are firm-specific.
Voluntary Disclosure of Advertising Expenditures
Authors: Simpson Ana
Published: July 2017

In this article, I examine the incentives for voluntary disclosure of advertising expenditures for a sample of U.S. firms for the period 1994-2003. I estimate proxies for the proprietary costs and valuation benefits of advertising with data from the mandatory disclosure period. My proxy for proprietary costs is an estimate of the spillover effects of advertising. It is measured by the association between a firm's advertising investments and its competitors' market values or future profitability. Valuation benefits are defined by an estimate of the relation between the firm's own advertising outlays and its market value or future operating income. I use these proxies to explain firms' discretionary disclosure decisions, and I find that firms that experienced high proprietary costs (valuation benefits) from advertising during the mandatory disclosure period are less (more) likely to disclose their advertising expenses in the discretionary disclosure period.
Analysts' Forecast Properties, Concentrated Ownership and Legal Institutions
Authors: Haw In-Mu , Ho Simon S. M. , Hu Bingbing , Wu Woody
Published: July 2017

Existing research indicates that firms with concentrated ownership structures are associated with poor financial reporting quality. This study investigates whether and how the divergence between control and cash-flow rights of controlling owners affects the effectiveness of analyst forecasting activities, and whether the effect varies with country-level legal institutions. Using a broad firm-level ownership data set for twenty-two economies, we find that control-cash flow divergence, on average, has no measurable effect on analysts' forecast properties across countries with varying legal institutions. We document rather weak detrimental effect of control divergence on forecast properties only in a small set of countries with weak legal institutions. Overall, our results indicate that the agency problems embedded in concentrated ownership structures do not always impede the private information production by analysts, which complements the previous evidence of the impact of concentrated ownership structures on corporate disclosures.
Executive Compensation, Compensation Consultants, and Shopping for Opinion: Evidence from the United Kingdom
Authors: Goh Lisa , Gupta Aditi
Published: July 2017

This paper builds on prior research on compensation consultants and executive pay, which finds widespread use of compensation consultants and higher levels of pay and proportions of equity based-pay in firms that employ consultants. Using a sample of FTSE 350 firms from 20022008, we provide new evidence that chief executive officers (CEOs) and executives of firms that switch their main consultant receive higher salary increments in the year of the switch (both absolute and adjusted for median peer levels) and a less risky compensation package, through a higher proportion of bonus and a lower proportion of equity pay. We do not find that executives of firms that increase their number of consultants have higher increases in compensation than nonincreasing firms. Our results provide some evidence that companies successfully engage in opinion-shopping between consultants for more favorable compensation packages for CEOs and executives.
Analysis of FASB Voting Patterns: Statement Nos. 1–86
Authors: Moody Sharon M. , Flesher Dale L.
Published: July 2017

The diversity of occupations among the members of the Financial Accounting Standards Board suggests that the resulting diversity of opinions would presage a virtual impossibility of standards setting unless coalitions exist. This study examines the possibility of employment-related coalitions. The findings show that, indeed, coalitions do exist under certain circumstances. Surprisingly, the Big Eight members of the FASB who appear to have a large potential voting power have not formed the controlling coalition that might have been expected.
Optimal Underwriting Contracts and Underpricing of New Issues
Authors: Bachar Joseph
Published: July 2017

The purpose of this paper is to analyze a new issue process in a model that focuses on the contractual relationship between an issuing firm and its investment banker, when the latter is assumed to have superior information regarding the market demand for the new securities. A “firm commitment” contract induces first-best choices of marketing effort and offer price by the banker, but is shown to be suboptimal for the issuer when the information asymmetry exists prior to contracting. The issuer's selection of a second-best underwriting contract is shown to result, under certain conditions, in the offer price set below the first best level. This “underpricing” result is explicitly explained and related to the empirical literature on underpricing. Finally, it is shown that, under a reasonable condition, the issuer does not lose value by delegating the pricing decision to the better informed investment banker.
Voluntary Disclosure
Authors: Dontoh Alex
Published: July 2017

The paper investigates incentives for firms to voluntarily disclose private information about future outcomes. A voluntary disclosure model that encompasses a competitive product market equilibrium and where proprietary (disclosure costs) costs are endogenously determined is presented. Possible explanations for empirical phenomena such as why value-maximizing firms voluntarily disclose unfavorable information (disclosures that cause investors to lower their expectations of firm earnings) when such disclosures tend to result in significant market price declines is provided. Existence of a unique Nash equilibrium where firms exercise discretion over such disclosures is demonstrated, and implications for extant empirical research on voluntary disclosures are discussed.
Valuation of Earnings, Cash Flows and their Components: An Empirical Investigation
Authors: Charitou Andreas , Ketz J. Edward
Published: July 2017

Security valuation has been in the forefront of the accounting and finance literature for many years. Although there is consensus that stock prices are related to future cash flows of the firm, there is controversy about the usefulness of the ex post earnings and cash flow measures in signaling stock prices. A cross-sectional equity valuation model is used to examine the incremental valuation content of earnings and cash flows in the marketplace. A sample of retail firms is used for the four-year period from 1980 to 1983. The results of this study indicate that (a) operating earnings have valuation content beyond operating cash flows, (b) operating cash flows do not have valuation content beyond operating earnings, and (c) the components of earnings, namely operating cash flows and accruals provide the same information to the market about future expected cash flows.
A Parsimonious Description of Individual Differences in Financial Analyst Judgment
Authors: Mear Ross W. T. , Firth Michael A.
Published: July 2017

This paper investigates the characteristics and properties of financial analyst judgment in a portfolio decision context. By adopting a research strategy which allowed for the emergence of different types of judges, the disagreement evident in subject response distributions was shown to reflect the characteristic styles by which financial analysts perceive and evaluate security prospects. These characteristic styles or categories of financial analyst decision behavior were subsequently explained by systematic differences in subject cue utilization strategies and subject demographic information.
Auditing Measurement Error and Statistical Sampling: The Dependently Occurring Case
Authors: Anderson John C. , Kraushaar James M.
Published: July 2017

This study investigates the potential effects of the inappropriate agreement, with the book value of some sampled units, on the behavior of statistical estimators and on the possible inferences that may be made by auditors. The results indicate that the resultant dependently occurring errors will adversely affect the inferences made by an auditor about the account balance of an account receivable population with a moderate book error rate. While the potential for an adverse effect from this type of error should be well known, the results of this paper indicate that the problem may be more serious than previously thought. A few dependently occurring measurement errors can have a significant impact on the appropriateness of an auditor's inferences. The results also indicate that dependently occurring and independently occurring measurement error may have conflicting effects, where the direction and significance of their combined effect depends on the account population being audited.
Capital Structure and Tax Status: New Evidence from IPOs
Authors: Miller Robert E. , Morris Michael H. , Scanlon Kevin
Published: July 2017

Theory suggests that tax status should influence the capital structure policies of firms. Empirical tests, however, have not conclusively validated the theory. Recent research suggests that even if firms optimize their operations to take advantage of the deductibility of interest on debt, other steps taken previously or concurrently with leverage changes may obscure the effect that tax status has on capital structure. By conducting tests on a sample of younger firms with recent initial public offerings, we investigate the effect of tax status on capital structure. Evidence from this sample provides support for the tax-incentive hypothesis.
An Empirical Analysis of Model Misspecification in Studies of Valuation of Financial Statement Disclosures
Authors: Beatty Anne , Chamberlain Sandra , Magliolo Joseph
Published: July 2017

A number of studies have examined the correlation between financial statement disclosures and share prices to assess the informativeness of these disclosures. There are several potential econometric problems with analyses of this type, and the interpretations of the results depend critically on the type of econometric problem. For example, the results of these studies should not be used to answer accounting policy questions unless the effect of an omitted variable bias is likely to be minimal. Given potential interpretation problems, we argue that analysis of model misspecification should be performed to isolate the form of misspecification. The contribution of this paper is to suggest a series of tests to perform this task. We use these tests to assess the importance of misspecification in adaptations of Barth's (1994) investment securities valuation model and Beaver et al.'s (1989) model of loan loss valuation. We find compelling evidence of the importance of misspecification apart from measurement error (e.g., omitted variables) in the model of investment securities valuation, but find only weak evidence of any misspecification other than measurement error in the loan loss valuation model.
An Empirical Test of the Signaling Effect of Management's Earnings Forecasts: A Decomposition of the Earnings Surprise and Forecast Surprise Effects
Authors: Yeo Gillian Hian Heng , Ziebart David A.
Published: July 2017

When corporate management issues an earnings forecast there are potentially two surprises. One potential surprise is that a forecast was issued and the other is the surprise in the earnings forecast. Accordingly, the observed stock market reaction to management earnings forecasts may be due to one or the other, or both. This study decomposes the cross-sectional variability in stock market reactions to management earnings forecasts into the portions attributable to the forecast surprise and the earnings surprise. The results indicate that the market's reaction is a function of both the earnings surprise and the forecast surprise. However, the market reaction is more associated with forecast surprise than with the earnings surprise. This suggests that results in previous studies on the market reactions to management earnings forecasts may need to be reconsidered.
Discussion: “Dispersion in Analysts' Earnings Forecasts as a Measure of Uncertainty”
Authors: Brown Lawrence D.
Published: July 2017

This paper tackles an interesting question; namely, whether dispersion in analysts' earnings forecasts reflects uncertainty about firms' future economic performance. It improves on the extant literature in three ways. First, it uses detailed analyst earnings forecast data to estimate analyst forecast dispersion and revision. The contrasting evidence of Morse, Stephan, and Stice (1991) and Brown and Han (1992), who respectively used consensus and detailed analyst data to examine the impact of earnings announcements on forecast dispersion, suggest that detailed data are preferable for determining the data set on which analysts' forecasts are conditioned. Second, it relates forecast dispersion to both analyst earnings forecast revision and stock price reaction to the subsequent earnings announcement. Previous studies related forecast dispersion to either analyst forecast revision (e.g., Stickel 1989) or to subsequent stock price movements (e.g., Daley et al. [1988]), but not to both revision and returns. Third, it includes the interim quarters along with the annual report. In contrast, previous research focused on the annual report, ignoring the interims (Daley et al. [1988]).
Individual-Firm Style Loadings, Unrecorded Economic Assets, and Systematic Risk
Authors: Ballester Marta , Livnat Joshua , Seethamraju Chandrakanth
Published: July 2017

This study estimates individual-firm style loadings for classification of individual securities into growth (glamour) and value groups. Style loadings are similar to betas, measuring the comovement of a firm's return with the return on a particular style index. The study examines this classification by comparing the extent of unrecorded economic assets for growth and value firms. The study also examines the systematic-risk characteristics associated with this classification.

Using Ohlson's (1995) valuation model, this study estimates the persistence of abnormal earnings for individual firms using time-series analysis. Growth firms are shown to have higher levels of abnormal earnings persistence than value firms, probably due to their greater levels of unrecorded economic assets than value firms. Indeed, the study finds that growth firms have greater levels of R&D and advertising intensity than value firms.

The study also shows that growth and value firms differ in their systematic risk. Possibly due to the greater uncertainty associated with unrecorded economic assets, the systematic risks of growth firms are larger than those of value firms.
Pharmacokinetic Evaluation of a New Maintenance Solution for Severely Injured Patients
Authors: Mosebach Karl‐Oskar , Stoeckel Horst , Caspari Rolf , Müller Robert , Schulte Jochen , Lippoldt Rita , Prahl Magdalene
Published: July 2017

Nine severely injured patients (SIP) and 9 healthy controls received 20 min iv infusions of Aminoplasmal‐LS‐10 (2.15 ml/kg body wt containing 0.215 g amino acids). Employing the values of the plasma amino acid (AA) concentrations 3, 7, 15, 30, 45, 70, and 150 min after the end of the infusion, we calculated the elimination half‐life (t1/2), the elimination constant (k2), the total clearance (Cltot), and the transfer of the individual AA. The AA showed t1/2 between 6 (Glu) and 23 (Thr) min. Comparing the metabolic kinetics of healthy controls and SIP, there were no statistical differences in t1/2 or in k2. In the SIP, nearly all plasma AA showed increased transfer and Cltot, significantly for Thr (p < 0.05), Pro, Gly, Ala, Arg (p < 0.02), Glu (p < 0.01), and Met (p < 0.005). In contrast, the Cltot for Phe and Tyr were decreased. Except for Phe, Tyr, Met (enhanced values) and Arg (no change), the fasting values of AA concentrations in the SIP were diminished compared to those in the healthy controls. Based on the measured transfer, we have developed a new maintenance solution adapted to SIP. Compared with Aminoplasmal, it is necessary to apply AA concentations which are increased in Lys, His, Phe, Tyr, Val, Ala, and Ser, and reduced in Arg, Pro, Leu, Ile, and Gly.
Thirty Years of Spanish Regional Change: Interregional Dynamics and Sectoral Transformation
Authors: Suarez-Villa Luis , Roura Juan R. Cuadrado
Published: July 2017

Impacts of structural changes on Spain's regional division of labor, economic growth, and interregional disparities are analyzed with long-series economic and population data. Three distinct time periods show contrasts in regional structure and development policies as growth gave way to crisis and then recovery. Changes in interregional disparities were mostly a function of spatial population redistribution, driven by the sectoral real-location of labor and employment and by differences in each sector's spatial orientation. Spain's experience has important implications for the future of the European Economic Community's regions and its policies, as a federal Europe emerges and attempts to reduce disparities between its member nations.
Physical Adsorption Studies on Mixed Vanadium Oxide Catalysts
Authors: El-Salaam K. M. Abd , Hassan E. A. , Said A. A.
Published: July 2017

Physisorption of N2 gas at 77 K has been used to measure the surface area (SBET) and porosity of V2O5 pure and mixtures with Fe, Co or Ni ions in atomic ratios extending from 1 to 50 at %. Calcination of samples was carried out between 473 and 873 K in flowing air. Adsorption isotherms are of type IV in the Braunauer classification with hysteresis loops of mixed A and B types, which reveal a very small external surface. Calculation of the pore volume distribution was carried out in addition to Va-t plots in order to study the surface porosity nature which was found to be mesoporous. Finally, the effect of foreign ions on SBET was discussed.
Porous Texture Characterization of Coals and Chars
Authors: López-Peinado A. , Rivera-Utrilla J. , López-González J. D. , Mata-Arjona A.
Published: July 2017

The chemical and physical characteristics of six Spanish coals and their corresponding chars were studied. Apparent surface area, density and porosity data were determined. The apparent surface areas obtained by CO2 adsorption at 298 K and 273 K are much higher than those obtained by N2 adsorption at 77 K. This indicates that a fraction of the micropropores of the samples is not accessible to the N2 molecules. The apparent surface area and porosity of the coal samples were studied as a function of the coal rank. The changes in the porous texture of the coal samples when they are thermally converted to chars were analysed.
Surface Characterization of Scheelites
Authors: García J. E. Herrero , Pinto J. M. Guil , Paniego A. Ruiz
Published: July 2017

Tungstates and molybdates of Ca, Sr and Cd have been prepared by precipitation. X-ray diffractograms prove them to be stoichiometric compounds with scheelite structure. The surface of the products and its evolution with thermal treatment have been studied by thermogravimetry and scanning electron microscopy. Finally, BET specific surface areas have been determined as well as pore volume distribution by adsorption-desorption of nitrogen and mercury porosimetry.
Microporous Adsorbents with Limiting Development of Micropores
Authors: Dubinin M.M. , Kadlec O.
Published: July 2017

The adsorption properties for benzene vapors and the pore structure of carbon adsorbents with a practically-limiting macropore volume have been investigated. The salient characteristic of the adsorbents studied was the position of the distribution curves of the micropore volume, whose maxima for the slit-shaped pore model corresponded to halfwidths of 1.2 to 1.4 nm and the micropore volume to 1.5 cm3 g–1. The difference in parameters of the Dubinin-Stoechli adsorption equation was only quantitative. The adsorption isotherms are very closely described by the DS adsorption equation in a broad range of equilibrium relative pressures and temperatures within 293–353 K. The question of the upper limit of micropore size in carbon adsorbents is also discussed.
Molybdenum Concentration Profiles in Thin Layers of Porous Supports
Authors: Morales M.I. , Blanco M.N. , Thomas H.J.
Published: July 2017

Impregnation of flat thin layers of porous supports by means of an unidirectionally flowing fluid has been studied. Since it is similar to pore-filling impregnation, this technique enables the qualitative behaviour of pellet impregnation to be predicted.

Aqueous solutions of ammonium heptamolybdate were used to impregnate both γ-Al2O3 and γ-Al2O3 samples containing 2.1 g Co per 100 g Al2O3. The molybdenum concentration profiles were similar in both supports. Thus both exhibited a plateau region over which an equilibrium existed between the concentration of adsorbed molybdenum and that in the solution within the pores, followed by a sharp decrease in which a shoulder was observed. This behaviour may be related directly to the shape of the molybdenum adsorption isotherms on both supports. Such profiles were analyzed using a theoretical model to estimate the kinetic parameters of adsorption. These parameters are useful for predicting concentration profiles of active species in pellets of any geometry.
Adsorption of Phenol from Aqueous Solutions on Activated Carbons with Different Oxygen Contents
Authors: Biniak S. , Kaźmièrczak J. , Swiatkowski A.
Published: July 2017

The effect of the chemical character of the surface of an activated carbon on phenol adsorption from aqueous solutions is described. The adsorbents used consisted of five types of activated carbon obtained by modification of the raw material. The results obtained indicate that the principal factor influencing adsorption is the oxygen contained in those surface functional groups which exhibit an acidic character. Moderately and slightly acidic groups are the most important in this context.
Adsorption Parameters and Surface Species in the Nickel—Molybdenum Alumina System
Authors: Rodriguez R.A.E. , Siri G.J. , Cáceres C.V. , Thomas H.J.
Published: July 2017

Isotherms corresponding to the adsorption of ammonium heptamolybdate solutions on nickel–alumina supports have been studied. Such isotherms exhibit two distinct adsorption regions, with both the support and the adsorbed species contributing to their formation. Two types of site are available for adsorption on the support and, depending on the molybdenum concentration present in solution, either monomeric (at low concentrations) or polymeric molybdenum species (at high concentrations) are formed and adsorbed. Monomer adsorption occurs at low concentrations, whereas polyanion adsorption predominates at high concentrations; the latter is reflected in an abrupt increase in molybdenum concentration adsorbed on the support.

The adsorption isotherms measured at 20°C and 50°C, and TPR and XPS studies indicate that the samples prepared at 50°C contain a lower quantity of octahedral molybdenum, although dispersion of the molybdenum on the surface is higher. In addition, a direct relationship exists between the dispersion of the active component and the hydrodesulphurization activity of the sample.

The presence of nickel on the support does not affect the total number of sites occupied by molybdenum. However, when the nickel content on the solid is increased, the molybdenum species occupy a higher proportion of octahedral sites. XPS studies have shown that samples with a higher nickel content possess a better dispersion of molybdenum species and exhibit a higher intrinsic activity. Enhanced molybdenum dispersion and thiophene conversion was associated with samples in which molybdenum adsorption occurred before nickel impregnation.

For all the series studies, the maximum value in the intrinsic acitivity occurred at the same value of the Ni/Mo atomic ratio. This provides convincing evidence that the precursor ratio is important in this catalyst system.
Criterion for the Quantitative Assessment of Ideal Conditions in Chromatography
Authors: Larin A. V.
Published: July 2017

The quantitative relationship between the plate theory variant model of equilibrium adsorption in which time is the only independent variable and the theory of ideal chromatogaphy has been evaluated. It has been shown that an approach to ideal conditions depends directly on an increase in the relative (or absolute) length of the column. Practical recommendations on the choice and assessment of conditions to verify the measurement of adsorption isotherms and on the calculation of chromatographic processes in accordance with the theory of ideal chromatography are given.
Nitric Acid-treated Bentonite Clay: A Novel Oxidation Supported Reagent
Authors: Theocharis Charis R. , Tomlinson John B. , Whelan Adam O. , Zychowicz George C.P.
Published: July 2017

Bentonite clay washed with 6 M nitric acid is active in the oxidation of benzaldehyde to benzoic acid. There is only one product, in addition to small amounts of carbonaceous material. The reactive species is believed to be nitrate ions present in the interlamellar species, together with an interlamellar acidic aluminium species which is useful in maintaining the crystallinity of the acid-washed clay. The reaction is possible when free 6 M acid is introduced into the reaction mixture together with untreated clay, but in that case more carbonaceous material is formed. There is evidence that acid treatment leads to the introduction of acidic aluminium species in the interlamellar region which may act as pillars; these are removed on washing.
Pore Structure of Crystalline Ferric Hydroxides and Oxides
Authors: Ruplis A.
Published: July 2017

Water vapour sorption isotherms at 20 °C of two series of crystalline ferric hydroxide powders (α and γ) are reported. Samples of the α-series were prepared from synthetic crystalline α-ferric hydroxide by thermal decomposition at a fixed temperature between 25 °C and 350 °C. Samples of the γ-series were prepared from synthetic crystalline γ-ferric hydroxide in the same way. It has been found that water vapour sorption isotherms on α-series samples exhibit a reproducible closed hysteresis loop located at p/p0 = 0.3–0.8. Both the shape and the location of the hysteresis loop change as the decomposition temperature of the samples increases. Initially, the hysteresis loop seems somewhat parallel to the pressure axis but later it becomes perpendicular. To explain this phenomenon, a pore structure model is proposed whereby a system with slit-shaped pores changes into one with pores open at both ends.
t-Curves for n-Hexane
Authors: Weber G. , Cougnard C. , Simonot-Grange M.H. , Bellat J.P. , Bertrand O.
Published: July 2017

The adsorption and desorption isotherms of n-hexane on powdered alumina and silica have been studied at 25°C over a wide range of relative pressures. Two t-curves for pore structure analysis are proposed, one for alumina (C = 12) and the second for silica (3 ≤ C ≤ 9). The statistical thickness t of the adsorbed n-hexane layer has been drawn as a function of the relative pressure assuming a maximal thickness of 0.55 nm and a mean thickness of 0.42 nm for the monolayer. The results are discussed in relation to previous published data.
Studies of the Dimensionless Mass-transfer Coefficient During the Adsorption of Basic and Acid Dyes on to Bagasse Pith
Authors: Nassar Mamdouh M. , El-Geundi Mohammed S.
Published: July 2017

The influence of agitation, particle diameter and mass of adsorbent on the external mass-transfer coefficient is discussed. The computed values correlate with the dimensionless function Sh/Sc1/3. It has been found that Sh/Sc1/3 varies linearly with the variables studied and may be correlated with system variables via the equation Sh/Sc1/3 = A(variable)B.
Kinetics of the Sorption of Organic Vapours in Chromatographic Silica Gel
Authors: Afzal M. , Khan M. , Ahmad H.
Published: July 2017

Organic vapours such as ethyl methyl ketone, methyl acetate, methyl alcohol, diethyl ether, acetone and acetaldehyde were adsorbed on to the chromatographic silica gel between 273 K and 297 K under a vacuum of 10–4 to 10–5 Torr. A Cahn 1000 electrobalance and an X–Y Beckman chart recorder were used for recording the data. Kinetic parameters such as rate constant, Knudsen diffusivities, bulk diffusivities and effective diffusivities have been calculated employing the Fick-type equation. The effect of temperature on the sorption of these organic vapours has also been discussed.
The Adsorption of Polymethacrylic Acid on Titanium Dioxide
Authors: Soltys M.M. , Yaremko Z.M.
Published: July 2017

The adsorption of polymethacrylic acid of molecular weight 10 × 103 and 70 × 103 was studied on highly dispersed titanium dioxide of the rutile variety. It was found that increasing the adsorbent content in the adsorption system led to decreasing adsorption. It was shown that the dependence of the adsorption on the content of adsorbent may be explained by the different degrees of redispersion of titanium dioxide particles in polymethacrylic acid solutions.
Organoindium Precursor Purification by New Sorbents Based on Titanium and Zirconium Phosphates
Authors: Grafova Irina A. , Khainakov Sergei A. , Strelko Vladimir V. , Battiston Giovanni A.
Published: July 2017

High purity requirements for organometallic precursors have recently become critical in the field of III–V semiconductor films obtained by chemical vapour deposition techniques. Traditional purification routes employing physical methods need to be replaced by ones which are more rapid and effective. Such a route is described in this paper. This involves the elimination of any traces of impurity by applying several combinations of sorbents. In this way, complete elimination of lithium impurities introduced during precursor synthesis has been achieved by the use of titanium or zirconium phosphate sorbents (usually used as acidic ion exchangers in aqueous media). The method also preserves the stability of the organoindium precursor which is normally extremely sensitive to moisture. A possible explanation for these observations is given.
Characterization of Carbon Beads Derived from Porous Polyimide Copolymer
Authors: Matynia T. , Gawdzik B. , Staszczuk P.
Published: July 2017

A new carbon sorbent obtained by the carbonization of beads of the porous copolymer of 4,4′-bis(maleimidodiphenyl)methane and styrene is described. To determine the influence of the carbonization process on the porous and chemical structure of the sorbent, nitrogen adsorption at low temperature, mercury porosimetry, quasi-isothermal analysis and chromatographic measurements were made.

The results indicate that polar imide functional groups were destroyed during carbonization, changing the chemical and porous structure of the sorbent. In consequence, non-polar porous carbon particles were obtained.
The Effect of Sulphur Dioxide Exposure under Controlled Environmental Conditions on the Challenge Performance of Copper and Chromate Impregnated Active Carbon against Hydrogen Cyanide
Authors: Anstice P.J.C. , Alder J.F.
Published: July 2017

An ASC/T (Cu2+, Cr6+, Ag and triethylenediamine impregnated) Whetlerite activated carbon sample was exposed to a flow rate of 1 l/min, 0.746 mg/l SO2 in 80% RH air at 22°C for up to 510 min. Samples were subsequently challenged with 2 mg/l HCN in an identical diluent gas stream. Increasing SO2 exposure resulted in accelerated HCN and (CN)2 bed penetration. The basic shapes of the breakthrough profiles were however essentially unchanged. This observation is in accordance with numerical analysis of these results using Hinshelwood's adsorption model, which suggested that the adsorption rate constant was not significantly affected by SO2 but rather the pollutant exposure resulted in the number of active centres on the carbon surface being reduced and the effective bed depth of the sample being shortened. This loss in active centres was thought most likely to result from the reduction of Cr6+ to Cr3+.
Influence of the Pore Geometry on the Micropore Size Distribution Function of Active Carbons
Authors: Choma J. , Jaroniec M.
Published: July 2017

A simple procedure for the evaluation of the micropore size distribution function of active carbons from the experimental adsorption isotherm of a single gas is discussed. In this method, the adsorption potential distribution and the dependencies of this potential on the micropore size for three different models, i.e. slit-like, cylindrical and spherical, are utilized. It was shown that the geometrical shape of pores may have a substantial influence on the micropore size distribution. While the micropore size distributions calculated assuming slit-like and cylindrical pore geometries are similar, spherical pore geometry leads to a substantially different distribution. A qualitative agreement was found between the micropore size distribution obtained by the current procedure, which is equivalent to the Horvath–Kawazoe method, and that evaluated by the density functional theory (DFT) method.
Textural, Structural and Catalytic Properties of Cr2O3/SiO2 Catalysts
Authors: Youssef A.M. , Ahmed A.I. , Samra S.E. , El-Assy N.B. , El-Sharkawy E.A.
Published: July 2017

Four chromia/silica samples containing 5–30 wt% CrIII were prepared by impregnation methods and calcined at 773–1173 K. Nickel, molybdenum and vanadium oxide-impregnated Cr2O3/SiO2 samples were also prepared by impregnation and were subjected to the same thermal treatment. The textural parameters of all the samples prepared were determined from the adsorption of nitrogen at 77 K, while X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to elucidate their structures. The catalytic properties of the solids so prepared in the catalytic cracking of cumene were investigated using a pulse microcatalytic technique.

The surface areas evaluated for the various Cr2O3/SiO2 samples studied were found to decrease gradually on increasing their CrIII content, the calcination temperature and on addition of Ni, Mo and V oxides. DTA and XRD studies demonstrated the absence of any interaction between the SiO2 and Cr2O3, with the latter being the only phase capable of detection by these techniques. Samples impregnated with Ni, Mo and V ions also showed no interaction between these ions and Cr2O3 and SiO2, with only the corresponding oxides being detected. The results obtained for the catalysis studies also indicated that the cracking of cumene depended on the metal content, impregnant cations and thermal treatment of the solids employed.
Standard Nitrogen Adsorption Data for Manganese Oxide and like (CBET = 40–60) Surfaces
Authors: Zaki M.I. , Al-Sagheer F.A. , Hasan M.A. , Kodiyan J.
Published: July 2017

Calcination to 1170 K of materials obtained by mild and intensive reduction of KMnO4 and HMnO4 solutions was found to produce manganese oxides assuming the crystalline bulk structure of α-Mn2O3 Nitrogen adsorption isotherms at 77 K revealed that they also assume non-porous surfaces of low specific area (4 ± 1 m2/g) with CBET equal to 40–60; t- and αs-curves derived therefrom were found to coincide with those determined reportedly on non-porous surfaces of 11 < CBET < ∞, irrespective of the surface chemical similarity. The experimental and reported standard adsorption data were used to analyze a type-IV nitrogen adsorption isotherm determined at 77 K on a porous manganese oxide (δ-MnO2) which was obtained by sol–gel processing of a KMnO4 solution, and found to similarly reveal a mesoporous surface of SBET = 73 m2/g and CBET = 125. The close agreement between the surface area values (St and Sα) derived for the test material (δ-MnO2) from the t- and αs-plots thus obtained and its CBET value (73 m2/g) was the basis on which reference materials with 11 < CBET < ∞ were found to be appropriate. Since most of the appropriate reference materials were dissimilar chemically to the test material, the results of the present investigation may imply that the surface chemical similarity demanded by the αs-method is better manifested in terms of the surface activity (heat of adsorption monitored by the CBET value) than the chemical composition.
The Hydrophobization of Active Carbons
Authors: Polyakov N.S. , Petukhova G.A. , Vnukov S.P. , Shevchenko A.O.
Published: July 2017

Three methods for the hydrophobization of active carbons (ACs) have been investigated, i.e. chemical modification, heat treatment under the influence of a ultrahigh frequency electromagnetic field and heat treatment under the influence of a low-frequency electromagnetic field. It is shown that methods involving physical modification are more preferable with the adsorbability of water on the treated AC over the relative pressure range 0.3 to 0.5 being decreased relative to the initial AC.
Equation of the Sorption Isotherm on Zeolite Y Including Heterogeneity of the Sorbent: A Novel Modification
Authors: Rozwadowski Michal , Wloch Jerzy , Kornatowski Jan , Erdmann Krzysztof
Published: July 2017

The complex character of water vapour sorption on zeolite Y has been demonstrated. It has been found that the assumptions of the Dubinin theory of volume filling of micropores (TVFM) are applicable to the description of such water vapour sorption. An equation for the adsorption isotherm is given which describes the experimental data in a satisfactory manner and which includes both the heterogeneity of the zeolite surface and the size distribution of the micropores participating in the sorption process. The equation yields realistic values of the total micropore volume which are close to the experimental sorption capacities. A significant effect of the sodium counterions on the sorption of water vapour has been found.
Peculiarities of the Protonation Reaction in the Interfacial Layer of a Silica Containing Covalently Bonded N-Methylaminopropyl Groups
Authors: Zaitsev Vladimir N. , Oleynik Viktoria D.
Published: July 2017

The reaction between an aqueous solution of a strong acid and the methylaminopropyl groups chemically bonded to a silica surface (A-NHCH3) was studied potentiometrically at various temperatures. Equilibrium constants were calculated on the basis of the law of mass action. It was shown that the interaction of acid with A-NHCH3 cannot be described within acceptable confidence levels by a single constant. At all temperatures studied, two types of chemical reactions had to be assumed: (1) protonation of an associate formed from adjacent amine molecules and (2) reaction of the charged associate with a second proton. The thermodynamic characteristics of the reactions were: ΔH1.2 = 25 ± 4 kJ/mol and ΔS1 = −17 J/(mol K), ΔS2 = +49 J/(mol K). The dynamic change in the structure of the interfacial layer was evaluated from the data obtained. It seems that after the first step in the reaction the surface associates remain unchanged. The second proton promotes a significant change in the geometry of the interfacial layer.
Calorimetric Investigations of Molecular Interactions in the Adsorbate/Microporous Activated Carbon System. Towards the Mechanism of Adsorption in Micropores
Authors: Terzyk A.P. , Rychlicki G.
Published: July 2017

This paper summarises the results of four years' investigation of the thermodynamics of adsorption in activated carbon micropores. Five adsorbates, i.e. methane, methanol, ethanol, carbon dichloride and carbon tetrachloride were adsorbed at three temperatures (308, 328 and 348 K) on two polymeric microporous carbons. Adsorption isotherms, as well as differential heats of adsorption, were measured using adsorption calorimetry. From the experimental results, the entropy as well as the average heat capacity of the adsorbed molecules were calculated. The data obtained lead to the mechanism of adsorption in carbon micropores as well as to the influence of the oxidation of the carbon surface on this mechanism. By comparing the isosteric and differential heats of adsorption, it is shown that the isosteric enthalpy cannot be applied for a correct description of the adsorption energetics. Finally, some empirical relationships describing low-coverage adsorption are proposed and discussed.
Synthesis and Modification of Catalysts for the Partial Oxidation of n-Alkanes
Authors: Golub N. , Gomonaj V. , Gomonaj P. , Szekeresh K.
Published: July 2017

The physical, chemical and catalytic properties of simple oxides and aluminosilicates of different composition, together with modifications of the same obtained by treatment with various reagents, have been studied experimentally. It has been shown that the use of simple oxides as catalysts led to the extensive oxidation of ethane while the use of aluminosilicates allowed the generation of formaldehyde, acetaldehyde and alcohols such as methanol and ethanol.

The presence of phosphorus in the modified catalysts favoured the formation of aldehydes and led to an increase in aldehyde concentration as well as the appearance of alcohols among the oxidation products of n-alkanes, e.g. ethane. Thus, the addition of phosphoric acid to γ-Al2O3 resulted in the formation of formaldehyde as a useful product.
Size Effects in Interlaminar Tensile and Shear Strength of Unidirectional Glass Fibre/Epoxy
Authors: Wisnom Michael R. , Jones M. I.
Published: July 2017

Curved beams tested in four point bending were used to measure interlaminar tensile strength, and straight beams loaded in three point bending to measure interlaminar shear strength. Results from specimens of 16, 32 and 64 plies with all dimensions scaled showed significant size effects. The average interlaminar tensile strength dropped from 109 MPa for the smallest specimens to 61 MPa for the largest, whilst the interlaminar shear strength was reduced from 97 MPa to 85 MPa.
Evaluation of Thermal Stresses at the Interface of a Stitch in a Stitched Laminate
Authors: Lee Ho Hyung , Hyer M. W.
Published: July 2017

The stresses in the vicinity of a single stitch through the thickness of an infinite cylindrical cross-ply laminate subjected to a unit temperature decrease are computed. Interest centers on the potential for microcracking in the vicinity of the through-thickness reinforcement. The infinite cylindrical cross-ply model is a simplification which leads to a tractible axisymmetric formulation, but which retains many of the three-dimensional features of the problem. In the model the stitch is a through-thickness cylinder consisting of fibers and resin, and the laminate consists of plys with fibers oriented radially and plys with fibers oriented circumferentially. Here only a [O/90]2s laminate is examined. Both glass and Kevlar stitches are considered, as is the possibility of resin pockets forming near the stitch. The results indicate that the presence of a resin pocket can alter the stress state in the vicinity of the stitch. In particular, the sign of a peak in the radial stress that occurs at the outside of the laminate changes from compression to tension when resin pockets are considered. The normal stresses in the resin pocket are all positive and their values are larger in the case of Kevlar stitch than in the case of glass stitch. This implies that the Kevlar stitched laminate is more likely to produce microcracking due to high residual stress after curing than the glass stitched laminate.
Curing of Thick Angle-Bend Thermoset Composite Part: Curing Cycle Effect on Thickness Variation and Fiber Volume Fraction
Authors: Naji Malak I. , Hoa Suong V.
Published: July 2017

The effect of cure cycle on the quality of angle-bend thermoset composite parts is presented. A 2-D finite difference scheme was used to model the processing of arbitrary shaped composite laminates. This model includes heat transfer, viscosity, rate of cure, and resin flow submodels. Experiments were done to investigate the effect of different curing cycles on thickness variation and fiber volume fraction distribution. Results from both simulation and experiment were compared.