Adsorption mechanisms of removing heavy metals and dyes from aqueous solution using date pits solid adsorbent

A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu2+), and cadmium ion (Cd2+) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu2+, and Cd2+ onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu2+ and Cd2+ ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g(-1), respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu2+, and Cd2+ onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu2+ and Cd2+. For Cu2+, binding two cellulose/lignin units together is the predominant mechanism. For Cd2+. the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit. (C) 2009 Elsevier B.V. All rights reserved.

Recruitment and Retention in Front-line Services: The case of childcare

This article highlights how problems of recruitment and retention in front-line services create a particular challenge to traditional HRM models and solutions. Private day nurseries make an interesting example of the challenges facing managers in the service sector as the combination of a feminised workforce, a price-sensitive service, public-private competition and state regulation create particular difficulties. We report on a study of 33 day nurseries involving interviews with managers and employees over an eight-month period. Our findings show that childcare providers have to cope with recruitment and retention problems associated with high-end interactive service provision compounded by gender segregation and small business characteristics. Our analysis of employer and employee perspectives examines labour market issues affecting recruitment, and categorises the reasons for staff turnover into internal 'push' factors, external 'pull' factors, outside factors and functional turnover.

Risks to home care workers: Professional perspectives

Care at home is fundamental to community care policy, but the simultaneous growth of health and safety regulation has implications for home care services because of the duty of employers towards home care workers. This grounded theory study set in Northern Ireland used data from 19 focus groups and nine semi-structured interviews with a range of health and social services professionals and managers to explore perspectives on planning long term care for older people. Home care workers faced a wide range of hazards in the homes of clients, who themselves were faced with adapting their living habits due to their changing health and care needs and 'risks.' Creative approaches were used to ensure the health and safety of home care workers and simultaneously to meet the choices of clients. Staff experienced feelings of conflict when they judged it necessary to impose their way of providing home care and thus impose their values on clients to create a safe working environment. There was variation between and within organizations in terms of the staff focus on client needs or on their employer responsibility towards home care workers. The planning of home care services must take account of both the choices of clients and the hazards facing home care staff.

Annotation of Case C-272/94, Criminal proceedings against Michel Guiot and Climatec SA, ECR 1996 I-1905

Employer's contributions - Loyalty stamps - Bad-weather stamps - Freedom to provide services - Posted Workers

Will attracting the creative class boost economic growth in old industrial regions? A case study of Scotland

Attracting in-migration of the creative class has been argued by Florida (2002) to be a route to higher economic growth in the era of the knowledge economy. This paper critically evaluates this proposition in relation to old industrial regions using the example of Scotland. The paper presents an assessment of, in the first instance, to what extent there is a shortage of skilled, talented and entrepreneurial individuals and, in the second instance, whether a talent attraction strategy alone can hope to attract such people to Scotland. It is proposed that for most migrants the availability of appropriate economic opportunities is a prerequisite for mobility. However, despite uncertain evidence that place attractiveness is a catalyst to mobility among the so-called creative class, this is not a reason for dismissing talent attraction programmes. Instead it is argued that talent attraction programmes have the potential to contribute to old industrial economies, but their success will be greatest when talent attraction is carefully targeted and based on economic realities rather than the marketing of ethereal conceptions of place attractiveness.

GERMAN WORKS COUNCILS AND THE ANATOMY OF WAGES

Using matched employer-employee data from the German LIAB for 2001, the authors found that German works councils are in general associated with higher earnings, even after accounting for establishment- and worker heterogeneity. Works Council wage premia exceed those of collective bargaining and are higher, in fact, where both institutions are present in the workplace. The authors also found evidence indicating that works councils benefit women relative to men and appear to favor foreign, east-German, and service-sector workers as well. Separate evidence from quantile regressions suggests that the conjunction of works council presence and collective bargaining is important to the narrowing process. In smaller plants even the presence of a works council markup depends on the coexistence of the works council entity With the machinery of collective bargaining.

The determinants of performance appraisal systems: A note (Do Brown and Heywood's results for Australia hold up for Britain?)

This article offers a replication for Britain of Brown and Heywood's analysis of the determinants of performance appraisal in Australia. Although there are some important limiting differences between our two datasets - the Australia Workplace Industrial Relations Survey (AWIRS) and the Workplace Employment Relations Survey (WERS) - we reach one central point of agreement and one intriguing shared insight. First, performance appraisal is negatively associated with tenure: where employers cannot rely on the carrot of deferred pay or the stick of dismissal to motivate workers, they will tend to rely more on monitoring, ceteris paribus. Second, employer monitoring and performance pay may be complementary. However, consonant with the disparate results from the wider literature, there is more modest agreement on the contribution of specific human resource management practices, and still less on the role of job control.

Stability of dust lattice modes in the presence of charged dust grain polarization in plasmas

We discuss the effect of the attractive force associated with overlapping Debye spheres on the dispersion properties of the longitudinal and transverse dust lattice waves in strongly coupled dust crystals. The dust grain attraction is shown to contribute to a destabilization of the longitudinal dust lattice oscillations. The (optic-like) transverse mode dispersion law is shown to change. due to the Debye sphere dressing effect, from the known inverse-dispersive ("backward wave") form into a normal dispersive law (i.e. the group velocity changes sign). The stability of one-dimensionless bi-layers, consisting of (alternating) negatively and positively charged dust particles, is also discussed. The range of parameter values (mainly in terms of the lattice parameter kappa) where the above predictions are valid, are presented. (c) 2005 Elsevier B.V. All rights reserved.

A hybrid metaheuristic approach to the university course timetabling problem

This paper describes the development of a novel metaheuristic that combines an electromagnetic-like mechanism (EM) and the great deluge algorithm (GD) for the University course timetabling problem. This well-known timetabling problem assigns lectures to specific numbers of timeslots and rooms maximizing the overall quality of the timetable while taking various constraints into account. EM is a population-based stochastic global optimization algorithm that is based on the theory of physics, simulating attraction and repulsion of sample points in moving toward optimality. GD is a local search procedure that allows worse solutions to be accepted based on some given upper boundary or ‘level’. In this paper, the dynamic force calculated from the attraction-repulsion mechanism is used as a decreasing rate to update the ‘level’ within the search process. The proposed method has been applied to a range of benchmark university course timetabling test problems from the literature. Moreover, the viability of the method has been tested by comparing its results with other reported results from the literature, demonstrating that the method is able to produce improved solutions to those currently published. We believe this is due to the combination of both approaches and the ability of the resultant algorithm to converge all solutions at every search process.

Adsorption and photocatalysed destruction of cationic and anionic dyes on mesoporous titania films: Reactions at the air-solid interface

Cationic dyes, such as methylene blue (MB), Thionine (TH) and Basic Fuschin (BF), but not anionic dyes, such as Acid Orange 7 (AO7), Acid Blue 9 (AB9) and Acid Fuschin (AF), are readily adsorbed onto mesoporous titania films at high pH (pH 11), i.e. well above the pzc of titania (pH 6.5), due to electrostatic forces of attraction and repulsion, respectively. The same anionic dyes, but not the cationic dyes, are readily adsorbed on the same titania films at low pH (pH 3), i.e. well below titania's pzc. MB appears to adsorb on mesoporous titania films at pH 11 as the trimer (lambda(max) = 570 nm) but, upon drying, although the trimer still dominates, there is an absorption peak at 665 nm, especially notable at low [MB], which may be due to the monomer, but more likely MB J-aggregates. In contrast, the absorption spectrum of AO7 adsorbed onto the mesoporous titania film at low pH is very similar to the dye monomer. For both MB and AO7 the kinetics of adsorption are first order and yield high rate constants (3.71 and 1.481 g(-1) min(-1)), indicative of a strong adsorption process. Indeed, both MB and AO7 stained films retained much of their colour when left overnight in dye-free pH 11 and 3 solutions, respectively, indicating the strong nature of the adsorption. The kinetics of the photocatalytic bleaching of the MB-titania films at high pH are complex and not well-described by the Julson-Ollis kinetic model [A.J. Julson, D.F. Ollis, Appl. Catal. B. 65 (2006) 315]. Instead, there appears to be an initial fast but not simple demethylation step, followed by a zero-order bleaching and further demethylation steps. In contrast, the kinetics of photocatalytic bleaching of the AO7-titania film give a good fit to the Julson-Ollis kinetic model, yielding values for the various fitting parameters not too dissimilar to those reported for AO7 adsorbed on P25 titania powder. (C) 2008 Elsevier B.V. All rights reserved.

So Why Did the Guns Fall Silent? How Interplay, not Stalemate, Explains the Northern Ireland Peace Process

The precise rationale for, and timing of, the Northern Ireland peace process of the 1990s and beyond, which developed after more than two decades of conflict, has yet to be fully explained. It has been a common assumption that it arose from a stalemate involving the Irish Republican Army (IRA), the 'regular' pro-state forces of the British Army and Royal Ulster Constabulary and the 'irregular/ultra' pro-state loyalist paramilitary groups of the Ulster Volunteer Force (UVF) and Ulster Defence Association (UDA). Under this interpretation, military/paramilitary deadlock led to ripeness for peace, amid reappraisals by all parties to the conflict of the utility of violence accompanied by reinterpretations of earlier political orthodoxies. The IRA could not remove the British sovereign claim to Northern Ireland; British forces could not militarily defeat the IRA and loyalists and republicans were engaged in a futile inter-communal sectarian war. This stalemate thesis has obvious attraction in explaining why a seemingly intractable war finally subsided, but is less convincing when subject to empirical testing among republican and loyalist participants in the conflict. This article moves away from 'top-down' generalist narratives of the onset of peace, which tend to argue the stalemate thesis, to assess 'bottom-up' interpretations from the actual combatants as to why they ceased fighting. It suggests an asymmetry, rather than mutuality, of perception that there was 'military' cessation by the armed non-state groups, with neither republican nor loyalist interpretations grounded in notions of stalemate. The article concludes by urging a wider consideration of the important and persistent interplay of the military and political in conflicts such as Northern Ireland.

Clustering and synchrony in laying hens: The effect of environmental resources on social dynamics

Laying hens generally choose to aggregate, but the extent to which the environments in which we house them impact on social group dynamics is not known. In this paper the effect of pen environment on spatial clustering is considered. Twelve groups of four laying hens were studied under three environmental conditions: wire floor (W), shavings (Sh) and perches, peat, nestbox and shavings (PPN). Groups experienced each environment twice, for five weeks each time, in a systematic order that varied from group to group. Video recordings were made one day per week for 30 weeks. To determine level of clustering, we recorded positional data from a randomly selected 20-min excerpt per video (a total of 20 min x 360 videos analysed). On screen, pens were divided into six equal areas. In addition, PPN pens were divided into an additional four (sub) areas, to account for the use of perches (one area per half perch). Every 5 s, we recorded the location of each bird and calculated location use over time, feeding synchrony and cluster scores for each environment. Feeding synchrony and cluster scores were compared against unweighted and weighted (according to observed proportional location use) Poisson distributions to distinguish between resource and social attraction.

Biosorption of toxic chromium from aqueous phase by lignin: mechanism, effect of other metal ions and salts

Surface reaction methodology was implicated in the optimization of hexavalent chromium removal onto lignin with respect to the process parameters. The influence of altering the conditions for removal of chromium(VI), for instance; solution pH, ionic strength, initial concentration, the dose of biosorbent, presence of other metals (Zn and Cu), presence of salts and biosorption-desorption studies, were investigated. It was found that the biosorption capacity of lignin depends on solution pH, with a maximum biosorption capacity for chromium at pH 2. Experimental equilibrium data were fitted to five different isotherm models by non-linear regression method, however, the biosorption equilibrium data were well interpreted by the Freundlich isotherm. The maximum biosorption capacities (q(max)) obtained using Dubinin-Radushkevich and Khan isotherms for Cr(VI) biosorption are 31.6 and 29.1 mg/g. respectively. Biosorption showed pseudo second order rate kinetics at different initial concentrations of Cr(VI). The intraparticle diffusion study indicated that film diffusion may be involved in the current study. The percentage removal of chromium on lignin decreased significantly in the presence of NaHCO3 and K2P2O7 salts. Desorption data revealed that nearly 70% of the Cr(VI) adsorbed on lignin could be desorbed using 0.1 M NaOH. It was evident that the biosorption mechanism involves the attraction of both hexavalent chromium (anionic) and trivalent chromium (cationic) onto the surface of lignin. (C) 2011 Elsevier B.V. All rights reserved.

Redundancy and Workplace Occupation: The Case of the Republic of Ireland

Purpose – This paper aims to examine the antecedent influences and merits of workplace occupations as a tactical response to employer redundancy initiatives.

Design/methodology/approach – The data are based on analysis of secondary documentary material reporting on three workplace occupations in the Republic of Ireland during 2009.

Findings – Perceptions of both procedural (e.g. employer unilateral action) and substantive (e.g. pay and entitlements) justice appear pivotal influences. Spillover effects from other known occupations may also be influential. Workplace occupations were found to produce some modest substantive gains, such as enhancing redundancy payments. The tactic of workplace occupation was also found to transform unilateral employer action into scenarios based upon negotiated settlement supported by third-party mediation. However the tactic of workplace occupation in response to redundancy runs the risks of potential judicial injunction and sanction.

Research limitations/implications – Although operationally difficult, future studies should strive to collect primary data workplace occupations as they occur.

Originality/value – The paper identifies conditions conducive to the genesis of workplace occupations and the extent to which the tactic may be of benefit in particular circumstances to workers facing redundancy. It also contextualises the tactic in relation to both collective mobilisation and bargaining theories in employment relations.

Relationship between job strain and smoking cessation: the Finnish Public Sector Study

Aims: To examine whether job strain (ie, excessive demands combined with low control) is related to smoking cessation.

Methods: Prospective cohort study of 4928 Finnish employees who were baseline smokers. In addition to individual scores, coworker-assessed work unit level scores were calculated. A multilevel logistic regression analysis, with work units at the second level, was performed.

Results: At follow-up, 21% of baseline smokers had quit smoking. After adjustment for sex, age, employer and marital status, elevated odds ratios (ORs) for smoking cessation were found for the lowest vs the highest quartile of work unit level job strain (OR 1.43, 95% CI 1.17 to 1.75) and for the highest vs the lowest quartile of work unit level job control (OR 1.61, 95% CI 1.31 to 1.96). After additional adjustment for health behaviours and trait anxiety, similar results were observed. Further adjustment for socioeconomic position slightly attenuated these associations, but an additional adjustment for individual strain/control had little effect on the results. The association between job strain and smoking cessation was slightly stronger in light than in moderate/heavy smokers. The results for individual job strain and job control were in the same direction as the work unit models, although these relationships became insignificant after adjustment for socioeconomic position. Job demands were not associated with smoking cessation.

Conclusions: Smoking cessation may be less likely in workplaces with high strain and low control. Policies and programs addressing employee job strain and control might also contribute to the effectiveness of smoking cessation interventions.