Clark Model Research Articles

Effectiveness of Group Cognitive Therapy for Social Anxiety Disorder in Routine Care

AbstractSocial anxiety disorder (SAD) is a prevalent chronic condition with a large demand for treatment. This community outpatient study examined the effectiveness of a group intervention version of the established one-to-one cognitive therapy derived from the Clark and Wells model for SAD. Questionnaires were completed pre-treatment and post-treatment for SAD symptoms (Social Phobia Scale, Social Interaction Anxiety Scale), depressive symptoms (BDI-II), self-focused attention, safety behaviours (Social Phobia Weekly Summary Scale and Subtle Avoidance Frequency Examination), and impaired functioning (Work and Social Adjustment Scale). From an initial sample of 159 participants, 101 completed at least seven of the nine weekly group sessions (Mage = 34.1 years, SDage = 10.8 years, 53% female). Significant improvements were demonstrated on all measures. Large effect sizes were found for social anxiety symptoms and safety behaviour use. Self-focused attention, depressive symptoms, and impaired functioning had moderate effect sizes. Effect sizes for anxiety (d = 1.00 and 1.32) and mood measures (d = 0.71) were as high, or in some cases, higher than previous group treatment studies. Results suggest group cognitive therapy for SAD based on the Clark and Wells model is effective in a clinical setting for individuals with moderate/severe and treatment-resistant social anxiety.

Batch and column adsorption of reactive dye by eggshell powder–chitosan gel core-shell material

In this study, eggshell powder-chitosan gel (EPCG) material was synthesized and tested as an adsorbent for two commercial reactive dyes in batch and dynamic modes. The EPCG material was a novel core-shell material in which the eggshell core particles were coated by a thin layer of chitosan. SEM images of dried EPCG powder showed a porous structure of the surface. In adsorption batch tests, Langmuir and Freundlich equations well described the adsorption isotherms with a maximum capacity of 2.3 mg/g at pH 4 and equilibrium time of 60 min (r 2 > 0.98). The adsorption process followed pseudo-second-order kinetics. Adsorption behaviour of EPCG toward the reactive dyes in fixed-bed adsorber was better described by the Clark model (r 2 > 0.92) than by the Bohart – Adam model (r 2 > 0.82). These results suggest that EPCG, as an environment-friendly material produced from waste eggshell, is very promising for wastewater treatment applications.

Optimization of fixed bed column process for removal of Fe(II) and Pb(II) ions from thermal power plant effluent using NaoH-rice husk ash and Spirogyra.

This study was carried out to investigate and optimize the potentials of green algae (spirogyra) supported with treated NaOH- rice husk ash in a fixed bed column for the removal of Fe(II) and Pb(II) ions from a thermal power plant effluent. The optimization was done with central composite design using the Design Expert 10.0.0 software. The effluent was characterised using atomic absorption spectrophotometer with initial concentration values of 17.9 and 4.95 mg/l for Fe(II) and for Pb(II) ions respectively. The developed rice husk-spirogyra adsorbent was characterized using proximate analysis, SEM, BET, FTIR and TGA. The results from the proximate analysis gave a moisture content of 13%, bulk density of 0.347 g/cm3, loss of mass ignition of 2.2 g, pH of 6.97 and pH point of zero charge (pHpzc) of 4.94. The SEM images revealed an adsorbent with numerous pores, cavities and an irregular rough surface. The FTIR showed the OH, C = O and CO functional groups as being responsible for the adsorption of the heavy metal ions. The BET analysis revealed high surface area of 534.414 m2/g with pore volume of 0.3219 cm3/g and pore size of 2.810 nm which reduced drastically to a surface area of 375 m2/g after adsorption. For the column sorption study, the effects of bed height, (5, 10 and 20 cm), at flow rate, (3, 6, and 9 ml/min), and initial concentrations of Fe(II) (17.9, 10.23, and 5.53 mg/L) and Pb(II) (1.65, 3.1, and 4.95 mg/L) established that an increase in bed heights, reduced flow rates and inlet concentrations gave over 48.3 and 58.30% removal of the Fe(II) and Pb (II) ions which had a significant effect on the breakthrough and exhaustion time. The data were subjected to kinetics isotherms with the Clark model given the best fit with R2 values of 0.9643 for Fe(II) and 0.9594 for Pb(II) ions.

Waste peanut shell modified with polyethyleneimine for enhancement of hexavalent chromium removal from solution in batch and column modes

To enhance removal of hexavalent chromium Cr(VI), peanut shell (PS) was modified by polyethyleneimine (PEI) and modified peanut shell (MPS) was obtained. MPS was characterized and the results indicated the success of modification. The batch and column modes were performed to study the adsorption property. It was in favor of Cr(VI) adsorption at acidic solution and the existence of common salts was not conducive. Electrostatic attraction was the major mechanism. The adsorption quantity toward Cr(VI) was up to 42.5 mg·g−1 at 293 K from experiments. Pseudo-second order model and Elovich model can predict kinetic process. Langmuir model and Freundlich model had great consistency with isotherm curves. Yan model and Clark model have better agreement with Cr(VI) adsorption in fixed-bed column. There was some characteristic of reuse for spent materials. It was concluded that MPS can availably eliminate Cr(VI) in wastewater and improve the utilization of PS in waste treatment.

Ridesourcing Behavior Analysis and Prediction: A Network Perspective

This paper investigates the spatiotemporal characteristics and predictability of the emerging modern traffic behavior, ridesourcing. We collect a comprehensive data set of Didi ridesourcing cars on a large geographical scale of a capital city in China, including both the temporal order information and the GPS-recorded spatial trajectories. To extract the features of this kind of traffic behavior, we construct a large-scale network by considering every traffic flow of the orders. Therein, a driver consecutively visiting different regions of the city connects the relationship of these sites. The weighted ridesourcing network shows a consistency of the distribution of trip orders and the Clark model for population distribution. The network also has spatial and temporal features with power laws, sometimes with exponential truncations and log-normal distributions. Furthermore, we propose a general analytical method to quantify the predictability of this kind of behavior by calculating the entropy at a collective level, which can be extended to quantify other traffic behaviors. Finally, by considering the traffic congestion factor, we propose a better neural network based model for predicting dwelling time of the ridesourcing behavior. We suggest that the traffic behavior of ridesourcing cars indicates specific non-Markovian characteristics, which can be systematically analyzed from the viewpoint of network sciences.

Arsenate and fluoride removal from groundwater by sawdust impregnated ferric hydroxide and activated alumina (SFAA)

Arsenate (As(V)) and Fluoride (F‾) are toxic elements found naturally in groundwater by natural and anthropogenic sources. Excess intake of Arsenate and Fluoride through drinking water cause several health effects; hence both must be removed from groundwater and make it potable. ‘Anjili’ tree Sawdust chemically modified by Ferric hydroxide and Activated Alumina (SFAA) used as an adsorbent. SFAA was characterized and the results are presented. The effect of initial concentration and contact time were studied. As(V) and F− adsorption by SFAA followed Freundlich adsorption isotherm, maximum sorption occurred at pH 6.5 and sorption kinetics followed the Pseudo-second-order model. The sorption capacity at 303 K and low initial concentration were found to be 2.42 mg/g for F, 0.10 mg/g for As(V). The column study gives an effective removal of both from the water. Among different models, Clark model fits well for arsenic and fluoride adsorption by SFAA.

Sisal xylem fibre-based activated carbon fibres for fuel adsorption: effect of thermal stabilization of diammonium phosphate

Activated carbon fibres (ACFs) are considered as the next generation of activated carbon products. However, lack of structural diversity in pore structure and high prices of raw materials for ACFs has restrained the development of ACF materials. In this paper, a sisal-based activated carbon fibre (SACF) material was prepared from sisal wastes with a unique thermal stabilization treatment to maintain fibrous shapes of SACFs while dispersing in solutions, and the SACFs were prepared as raw fibre materials for fuel evaporation emissions controlling products. Experimental results of N2 adsorption showed that SACF has a typical I-type adsorption isotherm, with specific surface area of SACF samples of approximately 1200 m2 g−1, and mainly microporous pore structure. Compared with commercial samples (specific surface area, 1841.29 m2 g−1), the butane working capacities of SACF for advanced fuel evaporation emissions controlling product was 0.4 g/100 ml higher. Furthermore, two dynamic models, Thomas model and Clark model, were applied to adsorption breakthrough data, which showed excellent fit. And it indicated from the adsorption breakthrough curves and parameters of both models that the SACF has better performance in fuel adsorption and desorption process than the commercial samples.

Removal of fluoride from an aqueous solution by batch and column process using activated carbon derived from iron infused Pisum sativum peel: characterization, Isotherm, kinetics study

The present study investigated the adsorption efficiency of magnetic activated carbon was synthesized by waste biomass of Pisum sativum (peel) and pyrolysis at 500˚C temperature (MPPAC-500). Derived activated carbon was applied for removal of fluoride from aqueous solution. The MPPAC-500 was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), zeta potential, X-ray Diffraction (XRD) and Particle Size Analyser. The fluoride sequestration study was performed in both batch and column systems. The batch adsorption study was focused on parameter like, adsorbent dose, contact time, pH and initial fluoride concentrations. The maximum capacity of fluoride removal was qo = 4.71 (mg/g). Freundlich isotherm model (R2 -0.995) obeyed better than Langmuir (R<sup>2</sup> -0.979) model. The RL values observed between 0-1 (RL-0.057) inferred the favourable adsorption. Pseudo-second-order model favoured well than pseudo-first-order in the whole experimental data. In case of column study was performed at two different bed height 5 cm and 10 cm having flow rate of 5 mL/min as well as 10 mL/min. The breakthrough curve and column data were interpreted by Thomas, Adams-Bohart, Yoon-Nelson and Clark model. These finding showed that MPPAC-500 has potential adsorptive capacity for fluoride removal from aqueous solutions in batch and column systems.

Effective defluoridation of industrial wastewater by using acid modified alumina in fixed-bed adsorption column: Experimental and breakthrough curves analysis

The defluoridation performance of a simple and efficient adsorbent (SAA), developed by H2SO4 treatment of alumina, was explored in fixed-bed adsorption column (FBAC). The SAA was characterized by SEM, EDX, FTIR, XRD and Raman spectroscopy. The influence of different process affecting parameters like bed depth (2.5–7.5 cm), influent flow rate (1.5–2.5 mL/min), and fluoride concentration (40–60 mg/L) were explored. The increased bed depth, and reduced flow rate and fluoride concentration were found to improve the column performance. The fitting of Thomas, Yoon-Nelson, Clark, BDST, and Yan models to breakthrough curves were attempted. The best fitting (R2 > 0.9) was exhibited by Clark model. The column exhibited the maximum performance at bed depth of 7.5 cm, influent flow rate of 1.5 mL/min, and fluoride concentration of 40 mg/L. The column performance of SAA was superior to unmodified alumina. The SAA (5 g) demonstrated the successful result (% R = 89.76%; tb = 350 min; te = 1037 min) for the treatment of industrial effluent (16.54 mg/L) in FBAC. Besides, the column loaded by SAA exhibited reusability up to four cycles. These results implied the suitability of SAA for the treatment of fluoride contaminated industrial wastewater or groundwater in continuous operating mode.

Development of fractal-like Clark model in a fixed-bed column

The Clark model was used to describe a fixed-bed adsorption system based on the combination of the mass-transfer concept and the Freundlich isotherm. The previous study revealed a time-dependent mass-transfer coefficient for the heterogeneous diffusion-limited process. Herein, this work proposed the fractal-like Clark model and its reliability was validated by the adsorption of norfloxacin on granular activated carbon. Moreover, the effects of the model parameters on the breakthrough curves and rate profiles were also investigated. The results indicated that the fractal-like Clark model had a high adjusted coefficient of determination (Adj. R2 > 0.977) and a small Akaike information criterion (AIC < −107.2) in all cases, providing more accurate estimation of the model parameters than the Clark model. As a three-parameter model, the Clark model could provide higher fitting accuracy (Adj. R2 = 0.997) for the adsorption of Cu(II) on Cystoseira crinitophylla biomass. The breakthrough curve became more asymmetric when the parameters n and h deviated from 2 and 0, respectively. The fractal-like Clark model may help readers to better understand the mass-transfer process in a fixed-bed column.

Bridging maladaptive social self-beliefs and social anxiety: a network perspective

The Clark and Wells (1995) model of social anxiety disorder postulates that three types of maladaptive social self-beliefs (high standard, conditional, and unconditional beliefs) play a crucial role in the development of fear and avoidance of social-evaluative situations—i.e., the hallmark symptoms of social anxiety disorder. In this project, we examined associations between the three types of maladaptive social self-beliefs and fear and avoidance of social-evaluative situations in a nonclinical community sample (n = 389). We used network analysis to estimate functional relations among aspects of maladaptive self-beliefs, fear, and avoidance and computed two different network models, a graphical Gaussian model (GGM) and a directed acyclic graph (DAG). Each model estimates edges and the importance of nodes in different ways. Both GGM and DAG pointed to fear and conditional beliefs as especially potent bridges between maladaptive social self-beliefs and social anxiety in our nonclinical sample. Altogether, these results offer data-driven heuristics in the field’s larger, ongoing effort to illuminate pathways at play in the development of social anxiety. We situate this study within novel network approaches for developing theory-driven models and tests of the instigation and interactions of maladaptive social self-beliefs and social anxiety. However, because this is the first study to combine GGM and DAG in social anxiety research, we also discussed the caveats to this approach to help to usher the field forward.

A Meta-Analytic Review of the Association Between Alienation Appraisals and Posttraumatic Stress Disorder Symptoms in Trauma-Exposed Adults.

Ehlers and Clark's (2000) cognitive model of posttraumatic stress disorder (PTSD) highlights the importance of negative appraisals in maintaining posttraumatic stress. Recent research suggests that alienation appraisals, defined as feeling disconnected from the self and others, mediate the association between traumatic experiences and subsequent PTSD symptoms. To our knowledge, no systematic review has yet explored the relation between alienation appraisals and PTSD symptoms in trauma-exposed adults, despite the important clinical implications posed by this association. A systematic search of the SCOPUS, Web of Science, PsycInfo, MEDLINE, CINAHL Plus, and PILOTS databases resulted in 470 studies, nine of which met full inclusion criteria. Studies were quality-assessed for risk of bias using the Quality Assessment Toolfor Studies with Diverse Designs(QATSDD) quality assessment tool. A random-effects meta-analysis for the association between alienation appraisals and PTSD symptoms showed a large total effect size, r = .57, 95% CI [.46, .66], z = 8.41, p < .001. This large effect suggests that as alienation appraisals increase, PTSD symptoms increase. Although a strong positive association was found between alienation and PTSD symptoms, the mechanism of this association remains unclear. Limitations of the research included significant heterogeneity across studies and the fact that data were correlational. Future research to explore why alienation appraisals are significant in posttraumatic stress may further help to inform therapeutic approaches to targeting alienation appraisals in trauma survivors. Recommendations are made for the clinical assessment of alienation appraisals when exploring the impact of the traumatic experience on the survivor.

Comment on ″Low-cost chitosan-calcite adsorbent development for potential phosphate removal and recovery from wastewater effluent″

In the adsorption studies, the accurate estimation of the model parameters contributes to getting insights into adsorption behaviors and optimizing adsorber design. After reading the research work of Pap et al. (2020) carefully, it was found that the fitting results were questionable. Thus, this comment tried to address the following aspects: (i) Correction of the fitting results for the kinetic and isotherm models; (ii) Correct form of the Bohart–Adams model; (iii) Usage of the Clark model; and (iv) Effects of the partial or complete experimental data on the model parameters. This work is expected to help readers better understand the adsorption models and estimate the model parameters.

A detailed thermal modeling of a passive single-slope solar still with improved accuracy

In the present study, a comprehensive approach is introduced to model a passive single-slope solar still. This approach is a proposed combination of Nusselt and Sherwood numbers. Unlike the conventional approach of solar still modeling which assumes the mean value of top glass pane and brackish water temperatures for the humid air temperature, the present thermal modeling includes the energy balance for humid air. Hence, the thermophysical properties of humid air are more accurately determined. Furthermore, the inclusion of brackish water salinity in equations as a decisive and effective parameter helped a lot with better determination of brackish water thermophysical properties. The top glass cover, brackish water and basin liner temperatures were determined by the proposed thermal modeling approach and the four well-known models i.e. Dunkle's model, Chen et al.‘s model, Clark's model and Zheng Hongfei et al.‘s model and the results were compared with the experimental data reported in literature. It was observed that the proposed thermal modeling approach is able to predict the temperatures of all three aforementioned components with higher coefficients of correlation and lower error values. Hence, the proposed approach provided a more accurate simulation for studying the thermal behavior of passive single-slope solar stills.

The optimal control of the consumer fund with the functions of the insurance company under assumption of the work on the financial market with the advertising strategy

Abstract The problem of dynamic system control in the form of the liability fund with the functions of the insurance company working in the financial market and developing the advertising strategy is considered. The generalized Clark model describes the price of risk asset. The optimal controls of the financial market asset portfolio and the part of capital the insurance company spends on the carrying out of the advertising companies were found under which the merit functional takes the largest value. The price of such control also was found.

Low-cost chitosan-calcite adsorbent development for potential phosphate removal and recovery from wastewater effluent

Phosphorous (P) recovery from wastewater will become increasingly vital in the future as terrestrial rock phosphate deposits are expended. Effective management of P as a critical resource will require new techniques to recover P from wastewater, ideally in a form that can be used in agriculture as fertiliser. In this study, batch and fixed-bed column conditions were tested using a novel KOH deacetylated calcite-chitosan based adsorbent (CCM) for P removal from aqueous solutions and wastewater effluents. The unique characteristics of this adsorbent as a phosphate adsorbent were the result of rich surface functionality (amine and sulphur functional groups of the chitosan and proteins) and the CaCO3 content (providing donor ligands; and additionally beneficial if the material were used as fertiliser, buffering soil acidification caused by nitrogen application). The maximum P adsorption capacity was determined to be 21.36 mgP/g (at 22 °C) and the endodermic process reached equilibrium after 120 min. The experimental data was best described using a Langmuir isotherm and a pseudo-second order kinetic model. The diffusion kinetic analysis highlighted the importance of both film and intraparticle mass-transport. Material characterisation suggested that the adsorption process involved interactions between P and functional groups (mostly –NH3+) due to electrostatic interaction on the chitosan chain or involved ligand exchange with CO32−. Analysis of materials using X-Ray Powder Diffraction (XRPD) and Thermogravimetric Analysis (TGA) indicated a microprecipitation-type mechanism may occur through the formation of hydroxylapatite (Ca5(PO4)3(OH)). Desorption studies demonstrated that the P-laden CCM (derived from crab carapace) had the potential to be reused in soil amendment as a slow-release P fertiliser. The effects of different operating parameters were explored in a fixed-bed column, and the experimental data fitted well to the Clark model (R2 = 0.99). The CCM also showed excellent P adsorption potential from secondary and final wastewater effluent in dynamic conditions, even at low P concentrations. Finally, a scale-up approach with cost analysis was used to evaluate the price and parameters needed for a potential large-scale P recovery system using this adsorbent.

WATER QUALITY ASSESSMENT, STATISTICAL ANALYSIS AND KINETICS OF TRIHALOMETHANES FORMATION IN DRINKING WATER SUPPLIES - A COMPLETE BATCH STUDY

The study attempted to identify the best suited models to determine the kinetics of chlorine decay and trihalomethanes (THMs) formation in drinking water supplies. Batch experiments were conducted on synthetic water samples to simulate the characteristics of raw water collected from Maithon water treatment plant (MWTP), Dhanbad, Jharkhand, India. Influence of various parameters like total organic carbon (TOC), reaction time, pH and chlorine dose on the rate of THMs formation were analysed. The studies revealed that above 50% of THMs were formed within the first 83.65 min. Later on the reaction rate decreases and it takes 7.329.26 hours for 99% formation of total THMs. Pearson correlation matrix dictated strong correlation of reaction time followed by pH, dose and TOC with THMs formation. Principal component analysis (PCA) demonstrated that dissolved organic carbon (DOC) is the most influencing parameter for THMs formation. Chlorine decay kinetics followed second order reaction and the rate constant was found to be 0.0131 L/mg.min-1. THMs formation kinetics was analysed by Clark and Kavanaugh model. Validation results indicated lower error of prediction (< 6%) for Clark s model than Kavanaugh model (< 20%). Thus, it was observed that Clark's model more suitably predicts the formation of THMs in Indian drinking water supplies.

Fixed bed adsorption treatment of effluent of battery recycling unit to remove Pb(II) using steam-activated granular carbon

Battery recycling generates large amount of effluent which contains the toxic Pb(II) beyond the permissible limit. This effluent was treated for the removal of Pb(II) by fixed bed adsorption onto steam-activated granular carbon. Effect of flow rate, bed diameter and bed height on the performance of fixed bed column was investigated. The experimental data was presented in the form of breakthrough curve. Bed exhaustion time, breakthrough time and adsorbent capacity were determined. The obtained experimental data were evaluated with the four kinetic models: Thomas, Yoon?Nelson, Adams?Bohart and Clark model. The data were fitted well to the Thomas, Yoon?Nelson and Clark model with correlation coefficient R2 &gt; 0.96.

Treating social anxiety disorder remotely with cognitive therapy.

To learn how to deliver all of the core interventions of CT-SAD remotely.To learn novel ways of carrying out behavioural experiments remotely when some in-person social situations might not be possible.

Modification of breakthrough models in a continuous-flow fixed-bed column: Mathematical characteristics of breakthrough curves and rate profiles

In order to more completely describe mathematical characteristics of the breakthrough curve, this work defines the four parameters: Maximum specific breakthrough rate μmax, lag time λ, inflection point ti and half-operating time t50. The breakthrough models include the Bohart–Adams, Thomas, Yoon–Nelson, Clark, Wolborska and dose-response models. Attempts are made to address mathematical relationships between the breakthrough models, propose modified breakthrough models, investigate effects of model parameters on the breakthrough curve and rate profile and reveal their physical meanings. The fitting performance of the breakthrough models is verified by the adsorption of nitrate on the chitosan-Fe(III) composite. The results indicate that the model terms q0m/vc0 and a0x/uc0 are the operating time required to reach 50% breakthrough. The Clark model has the best fitting performance with high adjusted determination factor (Adj. R2 = 0.9976) and low reduced chi-squared value (χ2 = 2.70 × 10−4). In addition, an inconsistency concerning application of the Wolborska model is proposed to avoid this situation where it is repeated in subsequent publications. This work is expected to help readers better understand the breakthrough models and select the appropriate model to analyze the dynamic behaviors in a continuous-flow fixed-bed column.