bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Physique Anxiety in Adolescence: An Exploration of Influences, Coping Strategies, and Health Behaviors
Authors: Sabiston C. M. , Sedgwick W. A. , Crocker P. R. E. , Kowalski K. C. , Mack D. E.
Published: December 2006

This study explored adolescent females’ experiences of social physique anxiety (SPA) and related coping strategies. A final sample of 31 adolescent females ages 13 to 18 years discussed dealing with SPA during individual semistructured interviews. Resultant themes pertaining to the transactional experiences of SPA were coded using content analysis. There were 107 unique coping strategies reported, which were coded into 10 subthemes. The main coping categories included behavioral and cognitive avoidance, appearance management, diet, social support, physical activity, reappraisal, cognitive deflection and comparison to others, seeking sexual attention, and substance use. Informed by a stress and coping framework, it is evident that body-related thoughts and emotions are linked to various adolescent health behaviors.
“I Hated Her Guts!”: Emerging Adults’ Recollections of the Formation, Maintenance, and Termination of Antipathetic Relationships During High School
Authors: Card Noel A.
Published: December 2006

Antipathetic relationships have received little empirical attention. This study examines these relationships by eliciting college students’ descriptions of the formation, patterns of interpersonal behaviors, and termination of antipathetic relationships during high school. Factors that differentiate inimical from other antipathetic relationships are also investigated. The Interview of Friendship and Antipathetic Experiences, a semistructured retrospective interview of high school relationships, was administered to 80 college undergraduate students (69% female, M age = 19.1 years). Quantitative analyses, supplemented by illustrative quotes, indicate that antipathetic relationships, relative to friendships or interactions with neutral peers, were marked by conflict during formation and aggression and avoidance during the relationship. Inimical relationships were differentiated from other antipathetic relationships by greater conflict in their formation, open expression of dislike, and aggression.
Effectiveness of Secondary Pregnancy Prevention Programs: A Meta-Analysis
Authors: Corcoran Jacqueline , Pillai Vijayan K.
Published: December 2006

Because subsequent pregnancy in teen parents often worsens the impact of adolescent parenting; therefore, a common goal of teenage parent programs has been to reduce repeat pregnancy. To examine the impact of this goal, a meta-analysis was conducted on 16 control-comparison group studies that evaluated the effect of teenage pregnancy and parenting programs on pregnancy rates. At the first follow-up period at which programs assessed outcome (average 19.13 months), interventions produced a 50% reduction in the odds of pregnancy compared to comparison-control conditions, but by second follow-up (average 31 mos.), the effect had dissipated. Moderator analyses were also performed. Implications are that secondary pregnancy prevention programs are effective in reducing teenage pregnancy—at least at 19 months following the intervention—although there is little to recommend “comprehensive” approaches to programming over others.
Views of Evidence-Based Practice Among Faculty in Master of Social Work Programs: A National Survey
Authors: Rubin Allen , Parrish Danielle
Published: December 2006

Objective: A national online survey assessed the views of 973 faculty members in master of social work programs regarding their receptivity toward, definition of, and views of disparate sources of evidence pertinent to evidence-based practice (EBP) and the teaching of EBP. Method: Due to Internet-related technical difficulties, the response rate could not be precisely determined; however, it was at least 33% and conceivably much higher. Results: Although the large majority (73%) of respondents expressed a favorable view toward EBP, disparities are identified among respondents in both the definition of EBP and views regarding the EBP research hierarchy. Conclusion: Efforts appear to be needed to increase agreement regarding the definition and conceptualization of EBP among educators, with special attention to divergent views regarding what constitutes sufficient evidence to guide practice decisions or to convey that an intervention is evidence-based.
Building Evidence: What It Takes and What It Yields
Authors: Gueron Judith M.
Published: December 2006

The author describes her 30 years of experience in the design and conduct of a series of large-scale randomized controlled studies in the field of public welfare. She describes how these studies came about, what lessons can be drawn about research methods, what was learned about the effectiveness of these programs (the National Supported Work Demonstration, the Demonstration of State Work/Welfare Initiatives, Aid to Families with Dependent Children, and Temporary Assistance to Needy Families), whether these studies impacted national social welfare policy, and what lessons can be applied from these studies to other fields. The use of randomized controlled studies is seen as the strongest research methodology to test large-scale social welfare policies.
Human Caring in the Social Work Context: Continued Development and Validation of a Complex Measure
Authors: Ellis Jacquelyn I. , Ellett Alberta J. , DeWeaver Kevin
Published: December 2006

Objectives: (a) to continue the development of a measure of human caring in the context of social work practice and (b) to expand a line of inquiry exploring the relationship between human caring characteristics and the retention of public child welfare workers. Methodology: Surveys were received from a sample (n = 786) child welfare workers in Georgia engaged in the delivery of direct services. Results : Principal components and alpha reliability analyses supported the multidimensionality of the human caring construct and measurement reliability for the sample. Additional validity evidence documented positive relationships between human caring and child welfare staffs’ intentions to remain employed in child welfare. Conclusions: The quantitative measure of human caring can be used in a variety of ways in social work practice (e.g., employee selection) and in future research that extends the human caring line of inquiry.
Therapeutic Components and Differential Treatment Outcomes Among Clients of Israeli Services for Substance Abusers
Authors: Schiff Miriam , Katz Katalin
Published: December 2006

Objective: This study is the first in a comprehensive examination of therapeutic components and outcome of interventions in a public, nonresidential service for drug addicts in Jerusalem (SHALEM). Method: Data were gathered from 153 clients (35 women, 128 men; 35 Arabs, 118 Jews; median age = 39) using clinical data mining. Results: Men who had been child victims of physical abuse (60%) showed less progress in treatment than men reporting no abuse. Arabs showed greater improvement in reducing violent acts. Only four therapeutic components were significant predictors of a client’s treatment outcomes. Conclusion: Processing of trauma history must become a major therapeutic component, and differential treatment plans for women and men and different ethnic groups should be developed.
Program Completion and Re-Arrest in a Batterer Intervention System
Authors: Bennett Larry W. , Stoops Charles , Call Christine , Flett Heather
Published: December 2006

Objective: The authors examine the effects of batterer intervention program (BIP) completion on domestic violence re-arrest in an urban system of 30 BIPs with a common set of state standards, common program completion criteria, and centralized criminal justice supervision. Method: 899 men arrested for domestic violence were assessed and completed 1 of 30 BIPs. At 2.4 years after intake, the authors reviewed arrest records and modeled domestic violence re-arrest using instrumental variable estimation and logistic regression. Results: There were 14.3% of completers and 34.7% of noncompleters re-arrested for domestic violence. Completing a BIP reduces the odds of re-arrest 39% to 61%. Conclusions: This study supports efforts to engage and retain men in gender-specific BIPs, as well as the value of examining larger systems of BIPs.
Role of Self-Determined Goals in Predicting Recidivism in Domestic Violence Offenders
Authors: Lee Mo Yee , Uken Adriana , Sebold John
Published: December 2006

Objective: This study investigated the role of self-determined goals in predicting recidivism in domestic violence offenders. Method: The study was a posttest design with an annual follow-up of recidivism data of 88 court-mandated batterers who attended a solution-focused, goal-directed treatment program. We hypothesized that goal commitment, goal specificity, and goal agreement would predict recidivism, and that confidence to work on goals would affect the degree to which these factors predicted recidivism. Results: The recidivism rate for program participants was 10.2%, and the final model accounted for 58% of variance in recidivism. The model indicated that goal specificity and goal agreement positively predicted confidence to work on goals, which negatively predicted recidivism. Conclusions: Significance of the study was discussed with respect to the potential positive impact of utilizing self-determined goals, language of “self-determination,” and “strengths and solutions” in batterer treatment as well as advances in social work intervention research.
Nonprofits as Civic Intermediaries
Authors: Leroux Kelly
Published: December 2006

Nonprofit organizations have a long-standing tradition of advocacy on behalf of their clients, particularly those that comprise underrepresented groups. However, much less is known about the roles these institutions play in empowering citizens to become active participants in the political process. This research note examines the efforts of nonprofit organizations to facilitate voting and contacting of public officials by their clientele. Results from this analysis suggest that social-service nonprofits located in urban areas are significantly more likely to encourage both voting and contacting. Findings also suggest that government funding has a positive and consistent effect on nonprofits' efforts to promote both of these forms of participation.
Race, Class, and Place
Authors: Clark William A.V.
Published: December 2006

There is an ongoing debate about levels of segregation, their causes, and their long-term direction. The debate is between those who, while acknowledging some role for economic forces, place the emphasis for continuing segregation on discrimination and White prejudice and those who place greater emphasis on income, wealth, and residential preferences. This debate is further illuminated with a detailed analysis of African American suburbanization using a combination of data from the 2000 Census and the Current Population Survey. The analysis confirms other research that shows substantial suburban growth of African American populations. It adds to that research by showing that those African American populations who move to the suburbs have substantially more income and wealth and higher levels of education than African American populations who move within the metropolitan cores. In addition, suburban African Americans live in more integrated settings than those who live in the central city. The implications of this finding bolster the view that income does matter in residential choices for African Americans.
Chemical dissolution techniques in the study of soil clays: Part I
Authors: Follett E. A. C. , McHardy W. J. , Mitchell B. D. , Smith B.F.L.
Published: December 2006

The mineralogy of the clay fractions of two soil profiles representing the end-members of a catena developed on a glacial till derived from basic lavas has been determined. Particular attention has been given to the assessment of the nature of the amorphous inorganic material in the clay fraction of these soils. Chemical dissolution techniques were used and their effects on the clay fraction were followed by X-ray diffraction, differential thermal, infrared absorption, electron-optical and surface area measurements. The principal conclusion is that the soil clays are a continuum from completely disordered, through poorly ordered to well crystallized material.
Argillization of basic hornfelses from the Land's End granite aureole, Cornwall
Authors: Floyd P. A.
Published: December 2006

Mineralogical and chemical variation in a 24 ft wide argillized zone in basic hornfelses from Gwavas quarry, Cornwall, is described and compared with variation in unaltered wall rock hornfelses.

Hydrothermal minerals developed are well-ordered kaolinite, sericite, chlorite, quartz, and limonite. Biotite has replaced hornblende as the dominant mafic constituent in the argillized zone. With increasing argillization kaolinite progressively replaces plagioclase, biotite, chloritized biotite, quartz, and finally Fe ore. No montmorillonite is present.

From the argillized zone, Si, Na, Ca, Mg, and Fe were extensively leached, although an approximate equivalent of H was added to compensate for the loss. Al and K are relatively constant throughout the zone. F was expelled from the most heavily argillized areas and is now concentrated in the biotite of the zone's margin as a marked ‘fluorine front’.

Two tenuous kaolinite-sericite zones are observed which are thought to be due to local variation in a single hydrothermal pulse with time.

Hydrothermal alteration of the hornfelses was effected in two stages (1) K+ metasomatism (biotitization) and (2) H+ metasomatism (kaolinization and sericitization).
A high-aluminous chlorite-swelling chlorite regular mixed-layer clay mineral
Authors: Heckroodt R. O. , Roering C.
Published: December 2006

One of the alteration products of a deuteric altered beryl is a high-aluminous chlorite-swelling chlorite regular mixed-layer clay mineral. An attempt was made to calculate the structural formula, and the results of X-ray, differential thermal and electron diffraction analyses are given.
Clay-organic studies. X. Complexes of primary amines with montmorillonite and vermiculite
Authors: Brindley G. W.
Published: December 2006

Basal spacing data for neutral amine complexes with montmorillonite and vermiculite are explained on the basis of two layers of fully extended amine molecules inclined at about 65° to (001) with the NH2 groups closely associated with pairs of silicate oxygen atoms. The molecular orientation is shown to be favourable for good intermolecular packing and for possible NH..O bonding, but the results do not constitute proof of such bonding. Packing of the molecules on the silicate surfaces and with respect to each other may explain the formation of double layer complexes. The amine data are correlated with corresponding data for the low-temperature (or below melting point) series of alcohol-montmorillonite complexes and it is suggested that the molecular layers may have some solid-like characteristics.
The mineralogy of some Upper Chalk samples from the Arundel area, Sussex
Authors: Weir A. H. , Catt J. A.
Published: December 2006

Seven samples, representative of all zones of the Upper Chalk in the Arundel area of Sussex, were treated with acetic acid and the residues analysed to determine their mechanical and mineralogical compositions. The sand and silt fractions of the residues consist mainly of flint and opaline silica, collophane, limonite, and quartz, and the clay fractions consist of montmorillonite, mica, quartz, and apatite. Authigenic apatite and quartz occur in the clay and silt and authigenic alkali feldspar in the silt. The montmorillonite may also be authigenic.
The diverse uses of montmorillonite
Authors: Hartwell J. M.
Published: December 2006

The industrial applications of Fullers' Earth are discussed including those of the clay in its natural form, calcium montmorillonite, and after modification by acid activation or sodium exchange. Special consideration is given to uses in oil refining, foundry bonding, civil engineering, and agriculture.
Urea complexes with montmorillonite : an infrared absorption study
Authors: Mortland M.M.
Published: December 2006

Urea was observed to become protonated in H-, Fe-, and Al-montmorillonite films and to form hemisalts when urea was present in excess of the number of available protons. The fully protonated urea disappeared upon dehydration, then the original protonated condition was re-established by rehydration. This completely reversible reaction indicates the importance of water in the protonated form. Indications were that urea will coordinate through the carbonyl group to the metal ion in Cu (II), Mn (II), and Ni (II) montmorillonite. Urea may be bonded to the metal ion in Mg-, Ca-, Li-, Na-, and K-montmorillonite by coordination and possibly by ionization of the N-H bond. The importance of ion-dipole interaction in urea complexes with montmorillonite is suggested. Decomposition of urea to ammonium ions was observed mainly in the Cumontmorillonite system.
Organo-metallic clay complexes
Authors: Bodenheimer W. , Heller L. , Yariv S.
Published: December 2006

Differential thermal analysis curves were obtained for a series of diamine and glycol complexes with natural and copper substituted montmorillonite, in air and in an inert atmosphere. Thermobalance curves of the diamine-clay systems were also determined. The exothermic peaks observed in air are characteristic for any particular system and reflect the nature and binding of the interlamellar material; no direct correlation was, however, observed with pyrolysis and oxidation processes in the clay. Organic matter is frequently liberated from the clay before oxidation, which then occurs within the reaction cell but outside the clay phase. The extent to which oxidation is completed at any particular temperature depends upon the supply of oxygen and the amount of organic material present.
Experimental studies of fine-grained micas
Authors: Rouxhet P. G. , Brindley G. W.
Published: December 2006

The surface properties of wet-ground muscovite were studied by thermodynamics of water adsorption. The surface appears to be covered by contaminating material, probably organic, which is strongly held; it was not removed at 350° C and under a vacuum of 10−4 torr. Attention is directed to the difficulty of maintaining freshly made silicate surfaces without contamination and to the importance of surface conditions in the interpretation of silicate properties which involve surface phenomena.
Vermiculite, hydrobiotite, and biotite in the Rainy Creek igneous complex near Libby, Montana
Authors: Boettcher A. L.
Published: December 2006

Vermiculite and hydrobiotite both occur as alteration products of biotite pyroxenite near Libby, Montana. Hydrothermal and weathering studies and new chemical analyses by C. O. Ingamells suggest that the vermiculite is a product of leaching of biotite by ground waters; the hydrobiotite may be a higher temperature alteration product.
Hysteresis in the crystalline swelling of montmorillonite
Authors: Laffer B. G. , Posner A. M. , Quirk J. P.
Published: December 2006

The crystalline swelling of sodium and potassium montmorillonites immersed respectively in solutions of sodium and potassium chloride of different concentration exhibits hysteresis in the swelling-contraction cycles. The position and extent of the hysteresis can be varied by altering the method of preparation of the clays; in all cases the hysteresis loops for potassium montmorillonite were more extensive than those for sodium montmorillonite.

The results have been explained in terms of a structural rigidity of montmorillonite crystals, where the crystals consist of five to ten aluminosilicate sheets (lamellae). The extent of hysteresis depends on this rigidity, which varies in a co-operative manner with the spacing between the lamellae in the crystal.

Electrical interactions between pairs of lamellae are also considered in analysing the swelling behaviour.
X-ray diffraction study of orientation of the micaceous minerals in slate
Authors: Fayed Laila A.
Published: December 2006

An X-ray diffraction technique has been used to determine the orientation pattern of the (001) planes of 10 Å micaceous minerals in slate. The guiding principle of this technique is the direct measurement of the diffracted radiation from the pre-selected family of crystallographic planes as a function of the orientation of the specimen.

Results obtained indicated that the basal planes of these minerals are mostly oriented in a direction parallel to the cleavage planes and the possibility of another orientation was considered to be slight.
Ionic composition of a disordered kaolinite
Authors: Worrall W. E. , Cooper A. E.
Published: December 2006

A white-burning, highly-plastic clay from Jamaica, containing mainly disordered kaolinite, was examined recently. It was unusual in that it was practically free from fine mica, and therefore could be purified readily by standard sedimentation techniques.

The cation exchange capacity was abnormally high, and the purified clay mineral, on analysis and calculation of the ionic composition, was found to be deficient in aluminium, but contained magnesium and iron.

The results confirmed the view, previously expressed, that disorder in kaolinites is associated with a high cation exchange capacity and a substituted lattice.
Clay-organic studies
Authors: Brindley G. W. , Thompson T. D.
Published: December 2006

Complexes are formed between a Ca-saturated fluorhectorite and organic molecules derived from propane by substituting benzene, pyridine, and piperidine rings in the 1,3 positions. The complexes are mainly of the A- and B-types described earlier by Greene-Kelly. Only one of the substances studied forms long-spacing complexes; in this case, the organic molecule is terminated at one end by a benzene ring and at the other by an active =NH group. Neutral forms of this molecule develop double-layer complexes, cationic forms develop single-layer complexes. The results are consistent with data for alcohols, alkyl chlorides and bromides, and alkyl amines.
Chemisorption of methylene blue by kaolinite
Authors: Faruqi F. A. , Okuda Susumu , Williamson W. O.
Published: December 2006

The chemisorption of methylene blue by kaolinite crystals increased as the aqueous suspensions changed from acid to alkaline because, at high pH values, not only the basal pinacoids but the edge-faces were negatively charged. The inability to calculate acceptable specific surfaces or cation exchange capacities from the chemisorption data is discussed, with special reference to the orientation of adsorbed dye cations, the covering of more than one exchange site by a monomer or polymer, the different concentrations of exchange sites on the basal pinacoids and edge-faces respectively, the possibility that such sites occur on the tetrahedral rather than on the octahedral basal pinacoid, and the incomplete replacement of inorganic cations.
Energy changes in dehydration processes of clay minerals
Authors: Sudo Toshio , Shimoda Susumu , Nishigaki Shigeru , Aoki Masaharu
Published: December 2006

Using the adiabatic calorimeter which has been developed by Nagasaki & Takagi (1948) and manufactured by the Rigaku Denki Company, the energy changes associated with the dehydration and dehydroxylation processes of clay minerals were measured at room pressure. The samples studied were mont-morillonite, chlorite (trioctahedral type), and three kinds of interstratified minerals with component layers such as mica, dioctahedral chlorite, and montmorillonite. ΔH-values due to the dehydration of the interlayer region were 9·8 kcal/H2O mole for montmorillonite and 12·4–13·4 kcal/H2O mole for interstratified minerals mica-montmoriIlonite and dioctahedral chlorite-montmorillonite. The values due to dehydroxylation of the silicate layer were 17·7 kcal/H2O mole for montmorillonite, 16·8–17·5 kcal/H2O mole for the interstratified mica- montmorillonite, and 19·3 kcal/H2O mole for chlorite. The value for the dehydroxylation of the hydroxyl layer of chlorite was 19·3 kcal/H2O mole. For the sake of comparison, the heat of transition α↔β of quartz was found to be 140 cal/mole. The reproducibility of these values was in the range of ±5%.
Hydration states of an expanded phlogopite in relation to interlayer cations
Authors: Thompson T. D. , Wentworth Sally A. , Brindley G. W.
Published: December 2006

A 2–20 µ fraction of phlogopite has been converted to the sodium form by use of sodium tetraphenylboron-NaCl solutions. The cation exchange capacity of the treated material increases to a maximum of about 212 m-eq/100 g, which agrees well with the K2O + Na2O content of the initial mineral. Li-, Na-, Ca-, and Mg-saturated forms have been prepared and examined by X-ray diffraction and by thernogravimetric measurements in air, in vacuo, and at progressively elevated temperatures. Hydration states corresponding to double water layers are observed for the Mg- and Ca- forms, and to single water layers for the Mg-, Ca-, Na-, and Li- forms. The numbers of water molecules per unit cell and per interlayer cation are considered for the various hydration states.
A study of hydroxyl groups in kaolin minerals utilizing selective deuteration and infrared spectroscopy
Authors: Wada Koji
Published: December 2006

The OH-OD exchange of kaolin minerals through contact with D2O introduced into interlayer space via intersalation resulted in a partial shift of the OH absorption bands. The total decrease in OH absorbance upon deuteralion was 52, 56, and 47% for the kaolinite, dickite-nacrite, and halloysite respectively, but the percentage decrease differed for the different absorption maxima of any one mineral. A secondary OH—OD exchange in the deuterated specimens was also observed upon heating to 350 and 400° C. These data together with the lack of deuteration in montmorillonite, and available orientation data on the kaolin OH groups by infrared spectroscopy, suggest that only two-thirds of the inner-surface OH groups form the interlayer OH—O bonds.
Quantitative X-ray diffraction analysis using clay mineral standards extracted from the samples to be analysed
Authors: Gibbs Ronald J.
Published: December 2006

In the quantitative X-ray diffraction analysis of a series of samples, the problems arising from the variable compositions and degrees of crystallinity of clay minerals were overcome to a great extent by the use of standards extracted from the samples. Procedures are given for separation of the montmorillonite standard by differential settling of Na-montmorillonite solvated in an ethanol solution and for isolation of the kaolinite, mica, and chlorite standards by density separation of their Na-forms in thallous formate.

Calibration curves were prepared from the X-ray diffractograms obtained for series of known mixtures of Ca-forms of the standards and the internal standard boehmite using both powder and smear-oriented mounting techniques.
The argillation of sub-marine tufts from the Mount Carmel, Israel
Authors: Singer Arieh
Published: December 2006

Absract

The alteration products of five sub-marine tuffs from the Mount Carmel were analysed chemically, by X-ray, D.T.A. and I.T.A. techniques and their mineralogical composition determined. Smectites are dominant in all the samples. In the less altered tuffs the smectite seems to consist of a mixture of saponite with a smectite from the beidellite-nontronite series. In the more intensely altered tuffs the saponite disappears and a swelling chlorite appears. The formation of the swelling chlorite is attributed to the degradation of the saponite. These mineralogical changes are accompanied by the loss of a large part of the alkali and alkaline earth cations.
The crystal structure of a pyridine-vermiculite complex
Authors: Susa K. , Steinfink H. , Bradley W. F.
Published: December 2006

A pyridine-vermiculite complex has been investigated by three dimensional X-ray diffraction techniques. The preparation of the complex was carried out at a pH ∼ 4 using a solution of pyridinium hydrochloride. Exsolved magnesium from the octahedral positions satisfied approximately one-half of the cation exchange capacity. The rest of the exchange capacity is satisfied by hydrogen ions and pyridinium ions which are statistically distributed over crystallographic sites so that less than three electrons per Å3 are present at any given point. Three dimensional difference electron density maps did not locate the carbon atoms except to indicate that the organic molecule occupies positions in the true and in the two pseudo mirror planes in the unit cell. Water molecules were present in the interlayer in octahedral arrangement around the cation as in the natural mineral.
Cation-dipole interactions in clay organic complexes
Authors: Bissada K. K. , Johns W. D. , Cheng F. S.
Published: December 2006

Quantitative gas chromatographic analyses supplemented by X-ray diffraction studies of the adsorption of ethanol and acetone (as model polar organic compounds) on homoionic montmorillonite revealed marked variation in the number of molecules associated with each exchange cation. The results show increasing association in the order K+ <Na+<Ba2+<Ca2+. K+ and Na+ associate with two and three molecules, respectively, of either ethanol or acetone, and the resulting complexes expand to form a monolayer (∼13 Å). Ba2+ and Ca2+ form both monolayer complexes as well as double layer complexes. In the single layer complexes Ba2+ associates with either four molecules of ethanol or four molecules of acetone, Ca2+ associates with five molecules of ethanol or four molecules of acetone. In the double-layer complexes the observed cation-molecule ratios are 1 : 8 for both Ba2+-ethanol and Ba2+-acetone, 1 : 10 for Ca2+-ethanol, and 1 : 8 for Ca2+-acetone.

The striking dependence of ethanol and acetone adsorption on the nature of the exchangeable cation suggests that cation-dipole interactions play an important role in the adsorption process. Structural models of the organic complexes are presented.
Sorption of α-amino-acids by copper montmorillonite
Authors: Bodenheimer W. , Heller L.
Published: December 2006

Sorption of an acidic, amphoteric, sulphur containing and basic α-amino-acid (glutamic acid, glycine, methionine and lysine) by copper montmorillonite was studied by chemical and X-ray methods. With glutamic acid complex formation occurs only in solution but increasing basicity of the aminoacid favours complex formation in the clay interlayers.
Mixed magnesium-aluminiun hydroxides. I. Preparation and characterization of compounds formed in dialysed systems
Authors: Gastuche M. C. , Brown G. , Mortland M. M.
Published: December 2006

The materials formed by dialysis of the precipitates formed by the reaction of NaOH with mixed Mg-Al solutions are described. In addition to aluminium and magnesium hydroxides, two hydrocarbonates having Mg/Al ratios of about 5 : 1 and 2 : 1 are formed, essentially pure, from solutions with Mg/Mg + Al molar ratios of 0.8 and 0.7, respectively. X-ray powder data shows that they have partially ordered hexagonal layer structures with unit layer dimensions a = 3.048 Å, layer thickness 7.60 Å for the Al-rich compound and a = 3.072 Å, layer thickness 7.92 Å for the Al-poor compound. X-ray and chemical data show that the new compounds resemble the minerals hydrotalcite and manasseite and also the compounds described as Mg-Al hydroxides by Feitknecht.
Mixed magnesium-aluminium hydroxides. II. Structure and structural chemistry of synthetic hydroxycarbonates and related minerals and compounds
Authors: Brown G. , Gastuche M. C.
Published: December 2006

A structural scheme is proposed for the synthetic Mg-Al hydroxycarbonates described in Part I (Gastuche, Brown & Mortland, 1967) based on chemical and X-ray powder data. The structure consists of positively-charged brucite-like layers in which Al replaces Mg up to a maximum of about one in three sites. The positive charge is balanced by an interlayer sheet containing carbonate groups and water molecules. The idealized structural formula for the Al-rich material is:

[Mg4Al2(OH)12]2+ [CO3.3H2O]2−.

A similar structural scheme seems to apply to many other materials including the minerals of the pyroaurite group, the compound 4CaO.Al2O3.13H2O and the related mineral hydrocalumite, a nickeliferous magnesium hydroxide mineral described recently and to many synthetic products that have been referred to as double sheet structures.
Hydrothermal aging of synthetic alumino-silicate gels
Authors: De Kimpe C. R.
Published: December 2006

Amorphous alumino-silicates of different compositions were aged at 175° C under acid and basic conditions. At high pH, crystallization of two zeolites, phillipsite and chabazite, was recorded. Under acid or neutral conditions, a demixing into boehmite and a more stable alumino-silicic gel has been observed.

These results are discussed in relation to the affinity of silica for alumina.
Solid solution formation of lepidocrocite-boehmite and its occurrence in soil
Authors: De Villiers J. M. , van Rooyen T. H.
Published: December 2006

Addition of aluminium to the ferrous sulphate mother solution used to synthesize lepidocrocite, γ FeOOH, yielded a substituted, though excessively hydrous (Fe,Al)OOH structure. Apart from reducing X-crystallinity, the main effect of isomorphous incorporation of aluminium in the lepidocrocite lattice was a shift, to higher values, in the temperature at which the lepidocrocite dehydration to maghemite was complete. Increased thermal stability of this substituted lepidocrocite, deduced from measurements of magnetic attraction made after serial heating, was consistent with the presence of a boehmitic component in solid solution. Magnetic susceptibility data for an oxisol indicated that a similar ferri-aluminous complex had developed pedogenically in the upper solum. This constituent was, however, amorphous to X-rays.
Stability of hectorite in weakly acidic solutions. II. Studies of the chemical equilibrium and the calculation of free energy
Authors: Tiller Kevin G.
Published: December 2006

The chemical equilibrium of a purified sample of hectorite was studied over a range of pH, silicic acid, and magnesium chloride concentrations. The quasi-equilibrium reached by about 6 weeks was reversible with respect to added magnesium ions but only partially so for added silicic acid. The free energy of formation of hectorite at 25° C was calculated at −2680 kcal/unit cell, using the derived equilibrium constant and the stoichiometry of the reaction as previously established.
A study of clay minerals in Podzol soils in New Brunswick, eastern Canada
Authors: Kodama H. , Brydon J. E.
Published: December 2006

Clays from the Ae and C horizons of five Podzol soil series in New Brunswick were examined by X-ray, chemical and infrared absorption methods. All the experimental evidence indicated that the Ae horizons contained predominantly a dioctahedral randomly interstratified mica-vermiculite-smectite clay, whereas the C horizons contained abundant dioctahedral mica (illite) and trioctahedral chlorite. Since no trace of chlorite as a separate phase or as one component of the interstratified structure was found in the Ae horizons, it was concluded that, while the inherited chlorite was decomposed in all of the Ae horizons, mica was differentially hydrated giving an interstratified structure. Fourier transforms of the three-component interstratified clay revealed different ratios of hydrated layers (vermiculite and smectite) to non-hydrated layers and different stacking sequences. The proportion of hydrated layers and randomness of stacking was related to the degree of weathering as measured by the accumulation of TiO2 in the Ae horizon and it was suggested that they may be related to the degree of podzolization.
The origin of the montmorillonite of the European Chalk with special reference to the Lower Chalk of England
Authors: Jeans C. V.
Published: December 2006

The evidence is reviewed for the various hypotheses put forward to explain the origin of the Chalk montmorillonite.

Recent X-ray investigation of the mineralogy of the acid-insoluble clay fractions (buffered 2 N acetic acid at pH 3; <2 µ e.s.d.) of the Lower Chalk of England sheds light on the origin of the montmorillonite. The relations between the qualitative and semi-quantitative mineralogy of the clay fractions and the facies and stratigraphy in this formation have been studied in detail. Montmorillonite, illite, kaolinite, chlorite, vermiculite, pyrophyllite, mixed-layer minerals, quartz, low-temperature cristobalite and apatite have been identified; their semi-quantitative distribution reveals that two main antipathetic assemblages are present, between which all gradations occur. The first is characterized by montmorillonite, illite, quartz and by montmorillonite/illite (M/I) values of 0·7 and above; and the second by illite, kaolinite, chlorite, vermiculite and by M/I values of below 0·2. The distribution of these assemblages or of any particular mineral does not show obvious relations to the facies or stratigraphy.

There is strong evidence that the second of these assemblages is of detrital origin, introduced into the Lower Chalk seas by currents flowing mainly from areas to the east and south-east of England. There is no evidence to suggest that the montmorillonite and the illite of the first assemblage are of detrital or volcanic origin, and their distribution in the Lower Chalk is best explained by their neoformation in the sediment on the sea floor by precipitation from the porewaters. By extrapolation it is thought that most of the Chalk montmorillonite of clay-grade is of neoformational origin. Some from the Campanian and younger Chalks may be detrital. Locally in N.W. Germany and possibly Poland minor amounts may have been derived from the decomposition of volcanic glass in the Chalk seas.
Cation exchange in the interlayers of expansible layer silicates
Authors: Graf von Reichenbach H.
Published: December 2006

The relation between counter ion distribution, ion mobility and degree of contraction has been studied on hydrobiotite (2–5 µ size), equilibrated with mixed RbCl-SrCl2 solutions. From X-ray data, isotopic exchange and chemical extraction, it appears that the counter ions of the contracted portions of the interlayers are not in equilibrium with the solution phase. The distribution of counter ions in the interlayer space follows a gradient from the margin of the mineral to the centre. This distribution is the result of the interruption of a diffusion process, caused by the contraction of layers during exchange. Isotopic exchange is rapid on the external surfaces and in the expanded portions of the interlayers, but very slow in the contracted part, where the rate of exchange amounts to only 0.002–0.02 m-eq/100 g/day, and decreases with time. On exchange with MgCl2 solutions, secondary expansion of the interlayer space occurs and some of the counter ions trapped in the contracted regions are released.
Saponite from the Dalradian meta-Limestones of north-east Scotland
Authors: Wilson M. J. , Bain D. C. , Mitchell W. A.
Published: December 2006

The Dalradian meta-limestones of the Banffshire coast have been investigated as part of a study of the mineralogy of Scottish sedimentary and metamorphic rocks, the main purpose of which is to assess the extent to which soil minerals are inherited from such parent rocks. Saponite was found to be a common constituent of the non-carbonate fraction. Thin sections of the limestones were examined microscopically and the textural relationships between the saponite and the other minerals, particularly those of undoubted metamorphic origin, suggest that the saponite was formed during the metamorphism. Recent reports of the hydrothermal synthesis of saponite at elevated temperatures and pressures support this hypothesis.
Clay mineral provinces in the tertiary sediments of the Hampshire Basin
Authors: Gilkes R. J.
Published: December 2006

An X-ray diffraction study of over 600 specimens has shown that the Tertiary sediments of the Hampshire Basin are divided into two clay mineral provinces. The western province is characterized by kaolin from the West Country granites whilst the highly montmorillonitic sediments of the eastern province were partially derived from the dissolution of Chalk by tropical weathering.
Infrared spectroscopy in clay mineral studies
Authors: Farmer V. C.
Published: December 2006

Infrared absorption by a mineral arises from the vibrations of its constituent atoms, and the frequencies of these vibrations are dependent on the mass of the atoms, the restraining forces of the bonds, and the geometry of the structure. The resultant spectrum of absorption frequencies is a characteristic property of the mineral which can not only serve as a fingerprint for its identification, but also give, in favourable cases, unique information on features of the structure, including the nature of isomorphic substituents, the differentiation of molecular water from constitutional hydroxyl, the degree of regularity of the structure and an indication of the family of minerals to which an unknown mineral is related.
Stability of hectorite in weakly acidic solutions. III. Adsorption of heavy metal cations and hectorite solubility
Authors: Tiller Kevin G.
Published: December 2006

The heavy metal cations studied were adsorbed by hectorite suspended in 0.05 M calcium chloride as a pH-dependent reaction in the order, Cu > Zn > (Co, Mn) > Ni. The adsorption of heavy metal cations was accompanied by the removal from solution of silicic acid released by clay dissolution. It is proposed that the reaction takes place on edge surfaces such that the clay lattice is effectively extended. This result complements other work in which it has been shown that the adsorption of silicic acid by other silicate clays results in an increased adsorption of zinc, cobalt and nickel. The present study did not provide evidence of the exchange of zinc and other cations for lattice magnesium.

The solubility of hectorite was decreased in the presence of heavy metal cations in the same order that favoured their adsorption. It is proposed that they limit the dissolution of hectorite in weakly acidic solutions by adsorption on or near the sites most prone to proton attack, that is, the magnesium ions of the octahedral layer exposed at edges and defects.
Non-marine glauconitic illite in the Lower Oligocene of Aardebrug, Belgium
Authors: Porrenga D. H.
Published: December 2006

Thin green clay layers and lenses in the lower part of the Lower Oligocene Kerkom Sand near Aardebrug, east of Louvain in Belgium, were found to consist of glauconitic illite. This mineral contains about equal amounts of iron and aluminium oxides (14%) and is therefore intermediate in chemical composition between most illites and glauconites.

Comparison with the results of five published investigations of similar green clays in France and the United States shows that the green clays, which all have an intermediate glauconite-illite composition, are formed, unlike pelletoidal glauconite, in a non-marine environment. It is assumed that they developed in a lagoonal or hypersaline-lacustrine environment, probably as a result of the alteration of detrital illite-montmorillonite clay.
Differentiation of kaolinite from chlorite by treatment with dimethyl-sulphoxide
Authors: González García S. , Sánchez Camazano M.
Published: December 2006

Results from previous work on clay-mineral complexes with dimethyl sulphoxide are taken as a starting point for the development of a method to identify kaolin in the presence of chlorite. The use of this method with artificial mixtures of these minerals, and with soil clays allows the detection of kaolin when it is present in an amount higher than 5%, through the formation of a mono-layer complex with a basal spacing of 11.8 Å. Details for the use of the method are given.
A simple and rapid method to obtain a linear density gradient
Authors: Halma G.
Published: December 2006

A method is outlined and apparatus described to prepare rapidly and conveniently a reproduceable linear density gradient of any low-to-high value. The apparatus consists of two prismatic connected vessels of triangular shape one of which is inverted and tilted to a pre-calculated degree to account for the density difference of the liquids in the vessels. The liquids emerge, by gravitational levelling, from a common efflux tube connecting the vessels. 30 ml of density gradient can be withdrawn in 5 min. The linearity of the etflux is theoretically derived and shown experimentally using a number of organic liquids.
Electrical conductivity study on synthetic faujasites type X and Y
Authors: Schoonheydt R. , Uytterhoeven Jan B.
Published: December 2006

The electrical conductivity of synthetic zeolites, types X and Y has been studied to give information about the distribution and possibility of migration of the exchangeable cations, located at various sites. The Na+ samples were exchanged with K+, Cs+, Ag+, Li+, and NH4+. The various cationic forms were pressed into pellets and treated at 430°C under high vacuum for 24 hours. After cooling, the electrical conductivity and capacity was measured as a function of frequency (500–20,000 c/s) at various temperatures from −20°C up to 500°C. For each sample the reversibility was investigated. The experimental results allow the calculation of the specific conductivity, the real (ε′) and imaginary (ε″) part of the complex dielectric constant (ε*) and the loss factor tgδ.

The results show an ionic conductivity: the specific conductivity depends on the nature of the exchangeable cations as follows: Cs+ > K+ > Ag+ > Na+ > Li+. There is a different conductivity mechanism in the high temperature region compared with the low temperature region. At high temperatures (T > 400°K) the activation energy is independent of frequency. At low temperatures, a dielectuc absorption phenomenon occurs. The activation energy, calculated for this process was somewhat higher, but of the same order of magnitude as that of the high temperature region. It is suggested that the migration of the exchangeable cations in the supercage to interstitial positions gives rise to this dipole absorption phenomenon.

A comparison of the decationated Y zeolites with Na+Y and Na+X made it possible to attribute the conductivity to the cations in the supercage only. The exchangeable cations in the cubo-octahedra and in the hexagonal prisms lower the activation energy of the moving cations. Thus the energy of activation of X zeolites is lower than of Y zeolites.
Influence of the Van der Waals force on the infrared spectra of short aliphatic alkylammonium cations held on montmorillonite
Authors: Fripiat J. J. , Pennequin M. , Poncelet G. , Cloos P.
Published: December 2006

The aim of this paper is to show how van der Waals forces may account for profound changes in the IR spectra of alkylammonium saturated montmorillonite and the effect of adsorbed water molecules. IR spectra recorded on alkylammonium montmorillonite films submitted to vacuum and after exposure to water vapour show, in addition to the shifts in the stretching and deformation bands expected when hydrogen bonding is present, marked changes in the intensity of the CH2 and CH3 deformation bands. All these observations are explained by the following model: (1) in the absence of water, the aliphatic chains are tightly held between the oxygen atoms of the silicate layers with their axis parallel to the 001 planes; and (2) hydration causes a rotation of the organic chain of the dialkyl derivatives while it does not affect the orientation of the monoalkylammonium cations. Moreover in the former situation, the symmetric deformation band of CH3 is removed because of the increase of the reduced mass due to the immobilization of the chain between the oxygen atoms.