bluuebunny/crossref_metadata_2025_split huggingface dataset:
113Cd, 1H MAS NMR and FTIR Analysis of Cd2+ Adsorption on Dioctahedral and Trioctahedral Smectite
Authors: Di Leo Paola , Cuadros Javier 
Published: September 2003

AbstractDioctahedral and trioctahedral smectites of very low Fe contents were exchanged with Ca (0.8 N CaCl2) and then with Cd (0.004–0.2 N CdCl2), resulting in the approximate Ca/Cd interlayer compositions 100/0, 75/25, 50/50 and 0/100. The samples were analyzed using 113Cd and 1H MAS NMR spectroscopy, at different hydration states, and by FTIR using films oriented at 90 and 45° to the infrared beam. When adsorbed from low-concentration CdCl2 solutions, as in this study, Cd is in the smectite interlayer as Cd2+, surrounded by water molecules. In smectite specimens with no tetrahedral charge, Cd occupies one single site in the center of the interlayer along the c axis but in smectite with tetrahedral charge, the basal oxygen atoms with excess negative charge interact with some of the Cd atoms more strongly, generating a second site in which Cd is displaced from the center of the interlayer and closer to those oxygen atoms. The 1H NMR study showed protons from hydration water and smectite hydroxyls and showed that both have more than one component. The FTIR and 1H NMR experiments indicate that Cd interacts with hydroxyl groups through one of the solvating water molecules in the first coordination sphere. Cadmium retains water molecules bridging Cd and OH groups even at low hydration states. Comparison with previous studies shows that, when adsorbed from high-concentration CdCl2 solutions, Cd species other than Cd2+ are present in sufficient quantities to enter the interlayer and create a different Cd-water complex, seemingly displacing Cd2+ from the center of the interlayer.
Sorptive Characteristics of Tetraalkylammonium-Exchanged Smectite Clays
Authors: Chun Yuan , Sheng Guangyao , Boyd Stephen A. 
Published: September 2003

AbstractThe size of quaternary NH4+ cations defines their packing configurations in the interlayers and the basal spacings of organoclays, and hence strongly influences the sorptive properties of organoclays. A series of organoclays (TAA-SACs) was prepared from a smectite (SAC) fully exchanged with symmetrical tetraalkylammonium (TAA) cations of progressively increasing sizes with the carbon number of single alkyl group from 1 to 6. X-ray diffraction analysis indicated the packing configurations of monolayer, monolayer-to-bilayer transition, bilayer, and bilayer-to-trilayer transition in the interlayers of SAC. Calculations of the interionic distances between TAA ions support such packing configurations. Sorption of benzene by TAA-SACs displayed a high-low-high uptake trend and progressively weaker sorptive interactions as the size of TAA ions increased. Both the siloxane surfaces and TAA ions contributed to the overall sorption, with their relative contributions dependent on the TAA interionic distances and the basal spacings of TAA-SACs. High benzene sorption by small TAA-SAC (tetramethylammonium(TMA)-SAC) was attributed to the strong interactions between the siloxane surfaces and benzene molecules. With large TAAs, high sorption was due to the effective solute partitioning. Compared to benzene sorption, TCE sorption by small TAA-SACs (TMA-SAC and tetraethylammonium(TEA)-SAC) was less effective and displayed an abnormal trend, due largely to the lack of the siloxane surface-TCE interactions and to the stronger hydration of TMA as compared to TEA ions. The results provide strong evidence to support the use of either small or large quaternary NH4+ cations in preparation of organoclays as effective sorbents for removing organic contaminants from water.
HRTEM Image Filtration: Nanostructural Analysis of a Pillared Clay
Authors: Clinard Christian , Mandalia Tushar , Tchoubar Denise , Bergaya Faiza 
Published: September 2003

AbstractNanostructural analysis of pillared clay samples using high-resolution transmission electron microscopy has been developed. Montmorillonite samples were pillared using partially hydrolyzed Al and Fe solutions. Two samples, M01 and M05, corresponding to Fe/(Fe+Al) ratios of 0.1 and 0.5, respectively, were analyzed. The different steps of image filtration, resulting from filtration by ring-shaped masks, are illustrated and discussed from lattice imaging of sample M01. This procedure is used to show the heterogeneous distribution of the basal spacings in the different ordered domains. Domains of mesoporosity and distribution of the different Fe species are studied specifically in the sample M05. The quantitative HRTEM results are discussed and compared with X-ray diffraction patterns obtained from the same sample.
Influence of Cation Size on the Curvature of Serpentine Minerals: HRTEM-AEM Study and Elastic Theory
Authors: Perbost Régis , Amouric Marc , Olives Juan 
Published: September 2003

AbstractThe influence of cation size on the misfit between the tetrahedral and the octahedral sheets of serpentine layers, and thus on the curvature of serpentine minerals, has been studied using an experimental approach, based on scanning and high-resolution transmission electron microscopies (SEM and HRTEM, respectively) coupled with analytical electron microscopy (AEM), and a theoretical approach, based on the elastic theory of thin plates and the surface stress concept.Various Ni3(Si,Ge)2O5(OH)4 serpentine syntheses were prepared, with progressive tetrahedral substitution for Si by the larger Ge ion, the ratio Ge/(Si + Ge) ranging from 0 to 100%. Other parameters (temperature, time duration, water pressure) were fixed. From SEM-HRTEM observations and AEM analyses of all samples, two types of serpentine minerals were characterized: (1) curved structures of tubular or ‘roman-tile’ shape (curvature radius of 10 nm for 0% Ge, increasing with the Ge content), when the Ge tetrahedral content is <25%; (2) perfectly plane structures, with hexagonal or triangular shape (view normal to the layers), for greater Ge contents. These results prove the direct influence of cation size on the crystal curvature.From a theoretical point of view, a single serpentine layer with a misfit between its tetrahedral and octahedral sheets can be considered as an elastic thin plate subjected to two different surface stresses, σ+ and σ−, on its two faces. The difference σ+ − σ− between these two surface stresses was calculated from the above geometrical misfit, and the curvature of the serpentine layer was related to σ+ − σ−, according to the elastic theory of thin plates. The calculated curvature radii, and the Ge content of transition from curved to plane structures, are in agreement with the above observed values. Curved serpentine crystals may then be considered as a stacking of such elastically curved single serpentine layers.
Infrared Study of CO2 Incorporation into Pyrophyllite [Al2Si4O10(OH)2] during Dehydroxylation
Authors: Wang Ling , Zhang Ming , Redfern Simon A. T. 
Published: September 2003

AbstractWe report infrared spectroscopic observations of the incorporation of CO2 into pyrophyllite that has been heated between 200°C and 1250°C for periods of 15 min, 1 h and 5 days. The presence of CO2 is characterized by the ν3 band of CO2 near 2347 cm−1, detectable in samples in which dehydroxylation has commenced after heating above 450°C. With increasing temperature, the CO2 signal becomes more intense. The signal reaches its maximum intensity near 800°C with an annealing time of 15 min. Further heating leads to a decrease in the CO2 signal and the occurrence of an extra signal near 2156 cm−1 that implies the presence of CO. The process is characterized by significant time-dependence, indicating its kinetic nature. The peak positions of CO2 signals show systematic variations with temperature. Our results suggest that the CO2 molecule is associated with the local structure rather than being present as free gaseous CO2, and that the local structure of pyrophyllite is gradually modified during high-temperature treatments. However, no signals related to carbonate molecules ((CO32−)) were detected. The results suggest that CO2 or other carbon-based molecules may diffuse into some clay minerals during dehydroxylation and may become altered due to structural modifications at high temperatures. This may have significance for possible CO2 sequestration in shales and clay formations.
Removal of Anionic Contaminants using Surfactant-Modified Palygorskite and Sepiolite
Authors: Li Zhaohui , Willms Cari A. , Kniola Kristine 
Published: September 2003

AbstractIn this study, the feasibility of using surfactant-modified palygorskite (PFl-1) and sepiolite (SepSp-1) for removal of anionic contaminants from water was evaluated from batch experiments. The results showed that both minerals had strong affinity for hexadecyltrimethylammonium (HDTMA), a cationic surfactant used for surface modification. The HDTMA sorption capacities were 520 and 260 mmol/kg for PFl-1 and SepSp-1, respectively. Accompanying HDTMA sorption, the sorption of counterion bromide reached 380, and 210 mmol/kg, for PFl-1 and SepSp-1, respectively, indicating that the sorbed surfactant molecules form admicelles on the minerals’ surfaces. After modification by HDTMA to sorption maxima, these clays showed strong affinity for anionic contaminants such as chromate and nitrate. The chromate sorption capacities were 42 and 34 mmol/kg for HDTMA-modified PFl-1 and SepSp-1, respectively. Desorption of counterion bromide due to sorption of chromate followed a straight-line relationship, suggesting that the sorption of chromate on surfactant-modified palygorskite and sepiolite was also due to anion exchange as with other surfactant-modified clay minerals and zeolites.
Microwave Exfoliation of Vermiculite and Phlogopite
Authors: Obut Abdullah , Girgin İsmail , Yörükoǵlu Abdülkerim 
Published: September 2003

AbstractVermiculites and phlogopites can be exfoliated by chemical and thermal treatment methods to obtain chemically inert, adsorbent, fire-resistant, low-density materials with excellent thermal and acoustic insulation properties. The water content of the clay generally determines the extent of exfoliation and the presence of interstratification is claimed to increase the rate of exfoliation. Considering the strong interaction between water and microwaves, the effect of microwave power on exfoliation characteristics of vermiculites and phlogopites after treatment with water and hydrogen peroxide solution were studied at 600, 950 and 1300 W for microwave exposure times of 10, 20, 30, 60, 120 and 300 s. It was observed that the water molecules in the interlayers of the individual flakes were driven off quickly by microwave treatment causing layer separation in the samples. The vermiculite sample showed 2.8 and 5.6 times, respectively, the exfoliation ratio of the phlogopite samples, in accord with their water contents.
Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)
Authors: Cuevas Jaime , de la Villa Raquel Vigil , Ramirez Susana , Petit Sabine , Meunier Alain , Leguey Santiago 
Published: September 2003

AbstractThe chemical and structural properties of Mg smectites in the Vicálvaro sepiolite deposit have been studied in detail. The characterization was performed on different size-fractions of selected smectitic samples (5−2 µm; 2−1 µm; 1−0.5 µm; <0.5 µm and <0.1 µm). The chemical compositions of individual particles (5−1 µm) and of bulk undifferentiated fine fractions (1−<0.1 µm) were determined by energy dispersive spectroscopy-scanning electron microscopy and interpreted with the aid of X-ray diffraction (XRD) and infrared spectroscopy (IR) methods. The XRD and IR data demonstrate that all of the Mg smectite materials studied are mainly composed of a complex mixture of stevensite, saponite and mica-type minerals. Although the presence or absence of saponite cannot be confirmed absolutely, stevensite is a significant component of these Mg smectites. This is proven by the calculated layer charge reduction after the Hofmann-Klemen effect. The results are in close agreement with the suggested mechanism of topotactic overgrowth of stevensite on pre-existing phyllosilicate templates. This characterizes clay diagenesis in saline-lake systems.
Variety and frequency scales of antisocial involvement: Which one is better?
Authors: Bendixen Mons , Endresen Inger M. , Olweus Dan 
Published: September 2003

Purpose. The aim of this study was to examine whether a scale including frequency scores of antisocial behaviour is a more sensitive and better measure of antisocial involvement than a variety scale.Methods. Data from a representative sample of 1,292 Norwegian students aged 13 and 14 years was used to compare a 17‐item variety scale with two versions of a frequency scale covering the same 17 items. Internal consistency of the scales, stability coefficients (for 1‐year and 2‐year intervals), and associations with conceptually related variables (e.g. aggression, opposition, alcohol consumption) were examined.Results. Results indicated that using a scale including the (raw) frequencies of antisocial acts committed instead of a variety scale would result in reduced internal consistency, lower stability over time, smaller group differences and weaker associations with conceptually related variables. Similarly, in regression analyses the (raw) frequency scale contributed little to the explained variance in conceptually related variables over and beyond that contributed by the variety scale.Conclusions. Although the results for a log‐transformed frequency scale were about as good as for the variety scale, both practical, methodological, and to some extent, conceptual considerations argued against replacing the variety scale with the transformed frequency scale. However, there may be some minor benefits from using an appropriately transformed frequency scale as a supplement to a variety scale, and there are also situations where inclusion of frequency scores in antisocial scales may be essential.
Firesetting and playing with fire during childhood and adolescence: Interview studies of 18‐year‐old male draftees and 18 − 19‐year‐old female pupils
Authors: Perrin‐Wallqvist Renée , Norlander Torsten 
Published: September 2003

Purpose. The purpose of the present study was to investigate the interest of young men and women in playing with fire in childhood and as adolescents.Methods. Two interview studies were performed with fifty 18‐year‐old men and forty‐five 18‐19‐year‐old women.Results. The two studies showed that playing with fire is a common phenomenon among children. In the male group, 70% reported playing with fire in childhood, and in the female group, the proportion was 44%. None of the young men played with fire at the age of 18, while 44% of the young women did. In the draftee's study, playing with fire resulted in uncontrollable fires destroying three buildings, one car and a grass wall. There was one uncontrollable fire in the girls' study. The reasons for not playing with fire in childhood were said to be parental exhortation, prohibition, supervision, fear, and respect for fire. The motives for playing with fire in childhood were curiosity and distraction in the male group, and excitement‐seeking and amusement in the female group.
How do offenders define bullying? A study of adult, young and juvenile male offenders
Authors: Ireland Jane L. , Ireland Carol A. 
Published: September 2003

Purpose. The main aim of the present study was to explore how offenders define bullying and how this relates to school‐based definitions, with a subsidiary aim of exploring age differences.Methods. The sample was selected from two separate prisons in the UK housing male offenders (one adult prison and one housing both young and juvenile offenders) and consisted of 322 offenders (127 adults, 95 young offenders and 100 juveniles). Offenders were asked to complete a questionnaire designed to assess their perceptions of bullying, including an assessment of what types of behaviours made up bullying based on the Direct and Indirect Prisoner Behaviour Checklist (DIPC©: Ireland, 1999).Results. Differences were found between school‐based definitions and those applied by offenders. In particular, offenders reported that a single act of aggression could be considered bullying and that there was not always an imbalance of power between the bully and the victim. Victims were often seen to provoke bullies. Bullies were not always respected by their peers and one‐quarter of offenders felt that the term ‘bullying’ was a ‘childish’ one. Offenders reported a range of discrete aggressive behaviours, both direct and indirect in nature, which could be considered to be bullying. Indirect behaviours were reported as bullying less frequently than direct behaviours.Conclusions. The study demonstrated how school‐based definitions of bullying do not readily apply to offenders and the findings are discussed in relation to the specific population and environment under study.
Using the Psychological Inventory of Criminal Thinking Styles with English prisoners
Authors: Palmer Emma J. , Hollin Clive R. 
Published: September 2003

Purpose. This study considers the use of the Psychological Inventory of Criminal Thinking Styles (PICTS) within an English prison population.Method. The reliability and validity of the PICTS scales were investigated, and scores compared with data from an American prison population.Results. The results suggested that the PICTS was functioning in a similar way in both populations, although the English population's scores were higher. The calculation of test‐retest change scores over the duration of 6‐12‐month sentences allowed the sensitivity of PICTS scales to change over time to be analysed, an aspect of the PICTS functioning that had not previously been examined. This analysis over time suggested that evenwhen the effect of age was controlled for, changes were occurring over the duration of the sentence.Conclusion. The potential of the PICTS as a measure of change, aswell as assessment, is discussed.
Stalking actions, prior offender‐victim relationships and issuing of restraining orders in a Finnish sample of stalkers
Authors: Häkkänen Helinä , Hagelstam Camilla , Santtila Pekka 
Published: September 2003

Purpose. Various stalking styles were first clustered by using multidimensional scaling (MDS), and then different stalking styles were analysed against prior restrainee‐victim relationship and violation of the restraining order.Methods. The court and police files of a random sample of 240 Finnish stalking cases, in which a restraining order had been issued, were content analysed for the existence of 30 dichotomous stalking action variables. MDS was performed in order to identify different stalking styles.Results. The solution of a multidimensional scaling analysis suggested three distinct structural themes for the actions: instrumental/pursuit, instrumental/ manipulation and expressive/violence. The themes were partially associated with the nature of the prior victim‐restrainee relationship. In all, 35% of the restrainees violated the restraining order. No significant associations were found between violating the restraining order and restrainee, victim or circumstantial characteristics. Violation correlated significantly with the action themes instrumental/pursuit and expressive/violence. The number of stalking actions was also significantly higher for the stalkers who violated the restraining order. In addition, in all of the cases where the victim had voluntarily met with the restrainee, the restraining order was violated. Among the violators, the proportion of restrainees employing violent stalking actions and threats significantly decreased following the issuing of the restraining order.Conclusions. The results suggest that stalking can be interpreted thematically. Violation of the restraining orders is associated with certain stalking themes and the number of stalking actions. Further violence is decreased by the issuing of the restraining orders. Restraining orders playa significant role in victim protection and intervention.
Assessing reconviction, reoffending and recidivism in a sample of UK sexual offenders
Authors: Falshaw Louise , Bates Andrew , Patel Vaneeta , Corbett Carmen , Friendship Caroline 
Published: September 2003

Purpose. The rate of sexual reconviction for sexual offenders is known to be low. Sexual reconviction, however, is currently the most commonly used outcome measure in sex offender treatment evaluation studies. It is expected that sex offender treatment programmes will reduce the likelihood of reconviction amongst participants. A low base rate of sexual reconviction means that any reduction in reconviction (which could be attributed to treatment) will be small and unlikely to be statistically significant. This study aimed to assess other offence‐related outcomes for sexual offenders, in addition to reconviction.Methods. The sample comprised 173 sexual offenders who had completed a community sex offender treatment programme. Follow‐up information was collected forthe sample from programme files containing multi‐agency information. Official reconviction rates were also calculated using both Home Office and police data.Results. Collecting evidence of any offence‐related sexual behaviour during this study multiplied the sample's sexual reconviction rate by a factor of 5.3.Conclusions. The results show that broadening the outcome measure under observation indicates a higher level of offence‐related sexual behaviour displayed by sexual offenders than reflected by reconviction data. These results have implications for the outcomes measured in treatment evaluation research for sexual offenders.
The Youth Justice and Criminal Evidence Act 1999 andthe interviewing of vulnerable groups: A practitioner's perspective
Authors: Nield Roger , Milne Rebecca , Bull Ray , Marlow Kerry 
Published: September 2003

Purpose. To discover practitioners' appreciation of the legislative changes that the Youth Justice and Criminal Evidence Act 1999, largely implemented in 2002, will have on investigative interviewing of vulnerable groups.Method. Police officers and social workers completed a questionnaire that asked about their perceptions of the Youth Justice and Criminal Justice Act 1999.Results. Practitioners thought that a large number of interviewees would be eligible for the special measures allowed within the remit of the new act. It was believed that the act would result in achieving best evidence with respect to accuracy and recording of interviews and in less discrimination against vulnerable groups. However, it was believed that implementing the act would be demanding in terms of time and money.Conclusion. Police officers and social workers share positive and negative views concerning the implementation and efficacy of the new legislation.