bluuebunny/crossref_metadata_2025 huggingface dataset:
A three-parameter model for the venous pressure volume relation of the lower leg
Authors: van Langen H
Published: January 2004

Objectives: To derive a three-parameter model for the curvilinear venous pressure volume relation of the lower leg, and to test its consistency.

Methods: A model with venous pressure at rest (P0, mmHg), the venous compliance at P0 (C0, %/mmHg) and the venous stiffness constant ( k, 1/%) was derived. With strain gauge plethysmography the venous pressure volume relations of both legs at the mid-calf and at the ankle region were measured and fitted in 120 consecutive patients in the supine position.

Results: No difference was observed between the mid-calf P0 (right 8.1 ± 2.2, left 8.4 ± 2.1) nor between ankle P0 (right 10.1 ± 2.3, left 10.0 ± 2.1). A significant pressure difference of -1.8 mmHg was found between mid-calf and ankle. Leg side differences were not observed for either C0 at the ankle (right 0.36 ± 0.29, left 0.49 ± 0.85) or in the mid-calf region (right 0.54 ± 1.1, left 0.46 ± 1.0). Differences for the leg region but not for the leg side were found for k (mid-calf right 0.54 ± 0.38, left 0.64 ± 0.52, ankle right 1.32 ± 0.66 and left 1.33 ± 0.65).

Conclusion: The model demonstrated provided a proper description of the curvilinear venous pressure volume relation.
Eighty-five consecutive cases of cellulitis: clinical features, management and implications for hospital care
Authors: Butcher W B , Papworth S E , Parvin S D , Darke S G
Published: January 2004

Objectives: To determine lessons learned from a consecutive series of patients admitted with cellulitis, regarding factors leading to admission, management and duration of hospitalization.

Methods: Prospective data over a 12-month period within a district general hospital. Centralized admitting policy of all patients with a principle diagnosis of cellulitis under the vascular surgical department. Data comparison of younger patients vs older and of those hospitalized for less than one week vs more than one week.

Results: Of 85 patients admitted, 44 had previous oedema and 50 had a skin lesion as a portal for entry of infection; only nine had neither prior to the attack. Thirty-two had had at least one previous attack of cellulitis. Younger patients tended to have a more virulent systemic infection whereas older patients had more comorbidity and social problems. Fourteen patients required surgical intervention: eight had arterial and six had venous contributory circulatory disorders. Microbiological information was of minimal practical value. Surgical intervention and social problems were associated with delayed discharge.

Conclusions: The majority of patients with cellulitis had predisposing oedema/skin lesions and where these persisted or recurrent infection occurred long-term antibiotic prophylaxis may have been useful. Social problems and comorbidity remained complicating factors but more patients could probably have been managed in a domiciliary setting.
Surgery of varicose veins with transilluminated powered mini-phlebectomy: clinical experience
Authors: Scavée V , Theys S , Schoevaerdts J-C
Published: January 2004

The authors report their experience with a new surgical technique, the transilluminated powered mini-phlebectomy (Trivex' System, Smith & Nephew Inc, Andover, USA), to remove primary varicose veins. There were 70 patients, 50 women and 20 men, with a mean age of 52 ± 9 years. The average operating time was 56 ± 8 min (range 30–75 min). The mean number of incisions was five (range 2–8). The postoperative pain, cosmetic scores and all complications were evaluated prospectively.
Primary aneurysms of cephalic and basilic veins – a report of two cases
Authors: Maksimovic Z , Milic D , Havelka-Djukovic M , Tatic S
Published: January 2004

We present the cases of two patients with primary venous aneurysms of the upper extremity involving basilic and cephalic veins. This rare disorder is described with a review of the literature, where we found only seven previously reported cases of such aneurysms.
Thrombosis prophylaxis prior to surgery
Authors: Bergqvist D
Published: January 2004

This review article provides an update on risk factors of venous thromboembolism and methods for preventing its occurrence following surgery. A summary of the prophylactic methods that are currently available is provided, with particular attention given to low molecular weight heparins, which are the most popular. The new methods of Xa inhibition and oral thrombin inhibition are also mentioned. Finally, the most appropriate times to start prophylaxis and the necessary duration are discussed, along with some of the risks of prophylaxis.
Prevalence of chronic venous insufficiency in men and women in Poland: multicentre cross-sectional study in 40,095 patients
Authors: Jawien A , Grzela T , Ochwat A
Published: January 2004

Objective: To study the prevalence, clinical expression and risk factors of chronic venous insufficiency (CVI) in 40,095 Polish adults.

Method: This was a multicentre cross-sectional study with 803 participating primary care physicians.

Results: The study population was mainly female (84%). The mean age was 44.8 years. Of the total population, 10% presented with oedema, 34.3% had varicose veins, with approximately the same proportion in males and females and 1.5% presented with past or active ulceration. A similar prevalence of CVI to that observed in the developed countries was reported in Poland. Obesity, the number of pregnancies and a positive family history were found to be risk factors for CVI. Female gender was not shown to be a risk factor for varicose veins.

Conclusions: The relationship between the presence of symptoms and signs of CVI was high, whatever the gender. Thus, the previously described dominance of the disease in females is losing its significance.
Multi-layer compression: comparison of four different four-layer bandage systems applied to the leg
Authors: Ruckley C V , Dale J J , Gibson B , Brown D , Lee A J , Prescott R J
Published: January 2004

Objective: To compare on standardized laboratory models the performance of four commercially available four-layer bandage systems.

Methods: Four experienced bandagers applied each of the four systems [Profore® Regular (Smith & Nephew, Hull, UK), Ultra Four (Robinsons, Chesterfield, UK), System 4 (SSL International, Knutsford, UK) and K-Four® (Parema, Loughborough, UK)] to two models: a 12.5 cm diameter padded cylinder and a 9.5-14.5 cm padded cone. Bandages were applied individually in single layers and as a completed system using standard application techniques. Pressures were measured by the Borgnis Medical Stocking Tester at positions corresponding to ankle, gaiter and mid-calf areas as determined by the pressure sensor.

Results: A total of 768 observations were made: 384 for each model, 192 for each bandaging system, 192 for each bandager and 128 for each measuring point. The increase in pressure produced by each additional layer was in the range of 50-60% of the pressure achieved by the same bandage when used as a single layer. Each bandage system and each bandager produced a gradient of final mean pressure irrespective of whether the bandage was applied to a cylinder or a cone. However, there were no significant differences in the gradients between the four bandage systems or between the four bandagers. There were significant differences in the final pressures achieved among the bandage systems when applied as completed systems (mean: Profore® = 42 mmHg; System 4 = 45 mmHg; K-Four® = 48 mmHg; and Ultra Four = 51 mmHg; P<0.001).

Conclusions: These results challenge a commonly-held assumption concerning the additive effect of pressures generated by successive bandage layers. When applied as part of a multi-layered system each bandage adds just over half the pressure achieved by the same bandage when applied alone. The four completed systems produced pressures within a range appropriate for ulcer therapy, although there were significant differences in mean pressures. This capability of the systems to produce different pressures could be clinically important in the hands of inexperienced bandagers or with patients at risk of pressure damage..
Randomized clinical trial of varicose vein surgery with compression versus compression alone for the treatment of venous ulceration
Authors: Guest M , Smith J J , Tripuraneni G , Howard A , Madden P , Greenhalgh R M , Davies A H
Published: January 2004

Objectives: No randomized controlled trials exist to show whether varicose vein surgery improves healing of venous ulcers. In this study we investigated whether superficial venous surgery gave additional benefit to compression therapy in terms of healing rate, time to healing and quality of life of patients with venous ulcers.

Methods: A total of 121 consecutive patients with venous ulceration were identified, of which 45 were unfit/unwilling to be included. The remaining 76 (aged 38-89, 39 female) were randomized to receive either four-layer bandaging ( n =39) or superficial venous surgery (long and short saphenous with or without perforator surgery) and four-layer bandaging ( n =37). Ulcer healing and health-related quality of life (HRQL) were assessed.

Results: The healing rate was 64% (25/39) in the compression treatment group and 68% (25/37) in the surgical treatment group. This difference was not statistically significant (Pearson 2 P=0.75). There was no significant difference between the time to ulcer healing in the two treatment groups (log rank statistic=0.69, P value=0.41): median time 83 days for surgery vs 98 days for compression. After adjusting for duration of ulcer, size of ulcer and previous deep vein thrombosis, there was still no significant difference between time to healing for the two treatment groups (adjusted hazard ratio=0.79, 95% confidence interval 0.45-1.39). There was no difference in HRQL between the two groups, using the scores of a disease-specific questionnaire (CXVUQ).

Conclusions: This study suggests that for venous ulceration, superficial venous surgery gives no additional benefit to compression therapy from the point of view of healing rate and quality of life.
External valvuloplasty in the treatment of greater saphenous vein insufficiency: a five-year follow up
Authors: Geier B , Voigt I , Marpe B , Deska T , El-Gammal S , Stücker M , Barbera L , Mumme A
Published: January 2004

Objective: To present the results of external valvuloplasty of the saphenofemoral junction in selected patients with insufficiency of the greater saphenous vein after a mean follow up of 54 months.

Methods: A total of 54 legs were prospectively studied and re-examined a mean of 54 months after the operation. The severity of the patients' symptoms and their satisfaction with the procedure were recorded. Furthermore, the venous refill time, the severity of reflux and the diameter of the greater saphenous vein were recorded preoperatively and again at follow up.

Results: In 46 cases (85%) the patients were satisfied with the outcome of the procedure. At follow up, the mean severity of symptoms was significantly lower in every symptom category. The venous refill time was reduced by a mean of 5 seconds and the diameter of the greater saphenous vein was reduced by a mean of 3 mm. Reflux in the saphenofemoral junction despite the valvuloplasty was demonstrated in six legs (11.1%), and reflux in the distal saphenous trunk despite a competent valvuloplasty was seen in 18 cases (33.3%). When reflux was present at the follow-up examination, it affected a significantly shorter segment of the greater saphenous vein than preoperatively. Treatment for recurrent symptoms was necessary in 10 (18.5%) limbs.

Conclusions: External valvuloplasty of the saphenofemoral junction offers good results in terms of patient satisfaction, relief of symptoms and recurrence rate. With long-term results still pending, this vein-sparing operation might be an alternative to stripping in selected patients.
Popliteal venous reflux is not abolished by superficial venous ligation
Authors: Sharp M A , Nawabi D H , Walton J , Hands L
Published: January 2004

Introduction: The role of superficial venous surgery in the presence of deep venous reflux is not well defined. Abolition of deep reflux in the femoral segment after superficial venous surgery has been reported. The popliteal segment has not been investigated similarly.

Aims: To investigate if popliteal venous reflux can be abolished by superficial venous ligation.

Method: Retrospectively identified consecutive patients with mild category exclusive popliteal reflux were invited by post to attend for a repeat duplex scan after surgery. They had previously undergone superficial venous surgery aiming to eliminate all sites of superficial reflux identified on duplex scanning.

Results: Of the 34 patients invited, 21 attended: eight males and 13 females, mean age 60 years. Seven patients were suitable for bilateral investigation. Of the 28 segments scanned, the reflux category improved in three, deteriorated to the moderate category in six and remained unchanged in 18.

Conclusion: Superficial venous surgery does not abolish mild popliteal reflux.
Haemodynamic surgery for varicose veins: rationale, and anatomic and haemodynamic basis
Authors: Criado E , Juan J , Fontcuberta J , Escribano J M
Published: January 2004

The treatment of varicose veins has traditionally been ablative in nature and implemented without intent to improve the haemodynamic condition of the lower extremity veins. Haemodynamic surgery attempts to treat varicose veins by changing the reflux pattern while preserving the most efficient venous drainage channels. To implement this treatment modality it is necessary to have a clear understanding of the physiologic principles and the different reflux patterns that form the basis of haemodynamic surgery. Haemodynamic surgery is an emerging treatment for varicose veins, and has received little attention in the English literature. The rationale, and functional and anatomic basis of haemodynamic surgery for varicose veins are herein described.
Quality of evidence underlying the management of thrombophlebitis
Authors: Mottahedeh M , da Silva A F
Published: January 2004

Objective: Superficial thrombophlebitis (ST) is commonly associated with varicose veins, although it may occur anywhere else in the body. The aim of this study was to review the quality of the evidence underlying the management of ST.

Methods: Review of the literature on the management of ST over a 20-year period carried out using Medline and manual searching. The current management of ST was then divided into levels of evidence as defined by the US Agency for Health Care Policy and Research.

Results: Superficial thrombophlebitis of varicose veins of the lower limb can be treated by saphenofemoral ligation with stripping of the proximal vein and surgical excision of the thrombosed segment (levels Ib and III). In the presence of deep vein thrombosis, oral anticoagulant (OC) is recommended (levels Ib and IIa). Hypercoagulable state should be investigated if ST occurs in the absence of varicose veins. In primary hypercoagulable state, disconnection of the saphenofemoral junction should be performed in patients at high risk of pulmonary embolism. Oral anticoagulant should be instituted after the first thrombotic event (level III). In secondary hypercoagulable state, OC with treatment of the underlying cause is recommended (level IV).

Conclusions: The quality of evidence supporting the management of ST varies considerably. Further randomized studies are required to support some of the current management methods.
Clinical spectrum of recurrent postoperative varicose veins and efficacy of sclerotherapy management using the compass technique
Authors: McDonagh B , Sorenson S , Gray C , Huntley D E , Putterman P , King T , Eaton T , Martin C , Harry J L , Cohen A , Guptan R C
Published: January 2004

Objectives: Tostudy the clinical spectrum of recurrent varices after surgery (REVAS) and the efficacy of sclerotherapy under the comprehensive objective mapping, precise image-guided injection, antireflux positioning and sequential sclerotherapy (COMPASS) technique in their management.

Methods: Design: prospective open study with 1.5-5.7-year follow up. Patients: 253 legs of 168 consecutive patients who had received previous surgery for primary varicosity.

Main outcome measures: obliteration, recanalization, residual reflux, neovascularization, venous dysfunction score and cumulative obliteration.

Results: REVAS presents as a symptomatic chronic venous disease of women in their fifties, a decade later than primary varicosities are reported. Almost 75% of REVAS occurred at the groin, mostly with features of chronic venous disease. The COMPASS technique achieved sustained obliteration in 97% of the groin varices and in 100% of the thigh and isolated refluxes around the popliteal fossa. The cumulative obliteration rate was sustained at >90% and obliteration of perforator reflux was sustained. There was a significant decrease in the venous dysfunction score. In the mean 3.1±1.7 years of follow up, only 3% possible neovascularization was seen. There were no serious adverse experiences reported.

Conclusions: REVAS is a symptomatic chronic venous disease requiring skilled medical attention. The COMPASS technique appears to be more efficacious than the presently available surgical approaches to its long-term management.
Exclusion of deep vein thrombosis by measuring spot skin temperatures using a hand-held thermo-comparator
Authors: Enoch S , Blair S D
Published: January 2004

Objectives: Thermograms have shown that deep vein thrombosis (DVT) causes an increase in temperature in the leg. We have studied for the first time, the viability of measuring spot skin temperatures using a hand-held instrument called a thermo-comparator as an inexpensive, simple and reliable method of excluding the diagnosis of DVT.

Methods: A total of 33 patients with suspected DVT had spot skin temperatures taken on specified areas of each leg using the instrument. The results were compared with duplex scans of the patient and with venography in some patients.

Results: There was a mean temperature gradient of 3.38°C down each normal leg. All 10 patients with DVT confirmed by duplex scan or venogram also had raised temperatures compared with surrounding areas, without the normal temperature gradient down the leg (true positive, 100%). This instrument did not have any false negatives and achieved 100% sensitivity and 100% negative predictive value.

Conclusions: The thermo-comparator excluded a diagnosis of DVT in 39% of patients and has the potential for use in primary care as a screening tool to reduce the number of patients sent to hospital unnecessarily.
Compression therapy and pressure in the deep venous system
Authors: Veraart J C J M , Oei T K , Neumann H A M
Published: January 2004

Objectives: To evaluate the effect of five different elastic compression stockings on the venous pressure in the deep venous system in the supine and standing positions.

Methods: Setting: Departments of Dermatology and Radiology, University Hospital Maastricht, The Netherlands.

Patients: A total of eight limbs of seven subjects (five patients and two healthy volunteers) with a mean age of 53 years (range 33-79) were measured. The patients were known to have severe venous insufficiency and recurrent leg ulceration. A catheter connected to an external pressure transducer was placed in one of the deep veins of the lower leg after puncturing the popliteal vein. The position of the catheter was established with contrast medium. Venous pressure recordings were made in the supine and standing positions while wearing an anti-embolism stocking and while wearing four different compression stockings (class II and III).

Results: All stockings worn in the supine position caused a significant increase in pressure when compared with no compression at all ( P <0.05; Wilcoxon rank test). Only the strong compression class III stockings caused a significant and clinically relevant pressure increase, compared with the other four elastic compression stockings ( P <0.05; Wilcoxon rank test). In the standing position no differences in pressure were found between the elastic stockings, or when any stocking was compared with the use of no stocking at all.

Conclusions: The results demonstrate that only strong compression class III stockings (>40 mmHg at the ankle) increase the pressure in the deep venous system in the supine position. Because of this, these elastic stockings may be the only stockings that have a positive influence on the pathologic deep venous system in patients with deep venous insufficiency, such as after deep venous thrombosis. The study confirms earlier clinical observations that in the treatment of patients with post-thrombotic symptoms and deep venous insufficiency only strong elastic compression stockings are effective.
Effect of body position and graduated compression stocking length on femoral venous blood flow velocity
Authors: Limpus A , Chaboyer W P , Purcell C , Schluter P J , Gibbs H , Beller E , Hetherington R
Published: January 2004

Objectives: To measure the effect of graduated compression stocking (GCS) length and body position on peak femoral venous blood flow velocity (PVV) and vessel diameter (VD).

Methods: Twenty healthy adult volunteers had PVV and VD measured, using colour Doppler ultrasound, at baseline in three body positions. Knee- or thigh-length GCS were assigned randomly.Arandom sequence of the three positions was used to measure PVV and VD. The procedure was repeated, after a two-hour washout period, using the other length GCS.

Results: There was no significant difference in the mean change of PVV ( P =0.74) or VD ( P =0.54) measurements from the baseline between thigh- and knee-length GCS. However, significant mean changes in PVV ( P =0.02) and VD ( P <0.001) measurements were observed for the three body positions, after adjusting for baseline values.

Conclusions: In healthy volunteers, thigh- and knee-length GCS do not have an effect on PVV or VD, and body position affects PVV significantly, with or without GCS.
The Aqueous Adsorption of Copper and Cadmium Ions onto Sheep Manure
Authors: Kandah Munther I. , Al-Rub Fahmi A. Abu , Al-Dabaybeh Naser
Published: January 2004

Dried sheep manure (SM) has been found to be an effective adsorbent for the removal of copper and cadmium ions from dilute aqueous solutions. Batch adsorption experiments using different concentrations of copper and cadmium ions (2.0–20.0 mg/ml) were carried out for different periods of agitation. Adsorption uptakes were found to increase with an increase in the initial metal ion concentration, SM concentration and solution pH for both copper and cadmium ions.

Maximum uptakes for 100 ppm Cu2+ and 100 ppm Cd2+ ions were found to be 17.8 mg/g and 10.8 mg/g, respectively. The equilibrium uptakes for both copper and cadmium ions were attained within the first 10 min. The Langmuir isotherm model failed to represent the adsorption of both copper and cadmium ions on SM. In contrast, the Freundlich isotherm model fitted the experimental data for both copper and cadmium ions very well. The presence of EDTA in the solution decreased the equilibrium uptake of both copper and cadmium ions significantly.
Effect of Functional Groups and pH on the Affinity and Adsorption Capacity of Activated Carbon: Comparison of Homogeneous and Binary Langmuir Model Parameters
Authors: Nouri Sirous
Published: January 2004

The adsorption of p-nitrophenol (an electrolyte) and nitrobenzene (a non-electrolyte) on activated carbon was carried out at 301 K under controlled pH conditions. The experimental isotherms were fitted to the homogeneous Langmuir model and the binary Langmuir model. Variation of the model parameters with solution pH was studied. The fitted parameters obtained from the Langmuir equations (homogeneous and binary models) showed that both the maximum amount of solute adsorbed (Qmax) and the adsorption affinity of the carbon (K1) towards the electrolytic adsorbate exhibited the more significant decrease. Under pH conditions below the pKa value of p-nitrophenol (when the adsorbate existed in a molecular form), both the solubility of the adsorbate and the electron density of its aromatic ring were significant factors affected the extent of London dispersion interactions. At higher solution pH values, electrostatic forces had a significant impact on the extent of adsorption. The influence of pH must be considered in terms of its combined effect on the carbon surface and on the solute molecules. It was confirmed that the uptake of the molecular forms of the aromatic solutes was dependent on the substituents attached to the aromatic ring. The adsorption of p-nitrophenol at higher pH values depended on the concentration of the anionic form of the solute present in the aqueous solution.
The Relationship between pH and Heavy Metal Ion Sorption by Algal Biomass
Authors: Tang Ying-Zhong , Gin Karina Y.H. , Aziz M.A.
Published: January 2004

The relationship between pH and heavy metal ion sorption by the biomass of two algal species was studied under controlled experimental conditions. It was observed that increasing heavy metal ion sorption by algal biomass with pH mainly arose from a change in algal cell properties, provided that the pH was below the level where the heavy metal ions started to precipitate. A drastic increase in metal ion sorption capacity (‘inflection point’) was observed at pH 4.5 for the algal biomass used in the study.

All the experimental observations on the mutual effects between pH and metal sorption for four heavy metal ions (Cd2+, Cu2+, Pb2+ and Zn2+) and two algal species suggested that the mutual effects between pH and heavy metal ion sorption can be explained in terms of ion exchange and coulombic attraction between the heavy metal ions and the algal biomass. A ‘positive feedback’ was also suggested for the mutual effects between pH and heavy metal ion removal at higher initial pH levels, where the sorption of heavy metal ions may enhance their hydrolysis.
Adsorption of Biologically Active Compounds from Aqueous Solutions on to Commercial Unmodified Activated Carbons. Part V. The Mechanism of the Physical and Chemical Adsorption of Phenol
Authors: Terzyk Artur P.
Published: January 2004

The study presented described the influence of temperature as well as pH on phenol adsorption (and the adsorption kinetics) on to three unmodified commercial carbons. The first section of the paper provided a description of the characterization of the carbons employing the most sophisticated method of carbon porosity characterization at present available, i.e. the method of Do and co-workers (the ND method). It was then shown that the ND method leads to the same results as the Density Functional Theory (DFT). The TPD results for D43/1, WD and AHD carbons were then presented and discussed with deconvolution of the peaks being performed. The results obtained together with those already published led to an assignment of the chemical structures of the surface functionalities for all the carbons studied. Thermogravimetric analysis of phenol adsorption indicated that the number of molecules bonded chemically was small.

Adsorption of phenol under acidic conditions (pH 1.5) was lower than at neutral pH for all the carbons studied. A description of the corresponding isotherms applying adsorbability, quasi-Freundlich and DA models, together with enthalpy measurements, led to a mechanism for the adsorption of phenol at both pH values. This mechanism was further confirmed by some empirical correlations and by a comparison with data obtained recently for modified chemically carbons. Some new correlations between the properties of the carbon surface and the constants characterizing the process of phenol adsorption suggested recently were extended from data which had been measured for six carbons initially. Analysis of the average hysteresis on the adsorption/desorption isotherms, as well as a comparison of phenol adsorption under oxic and anoxic conditions, led to a mechanism for the irreversible adsorption of phenol. It was suggested that such irreversibility resulted from two effects: the creation of strong complexes between the phenol molecule and surface carbonyl and lactone groups, as well as polymerization. The latter effect arose from the ability of carbon to adsorb oxygen from solution and form superoxo ions. A mechanism for such polymerization was proposed.

Finally, the kinetics of the process were considered. The diffusion coefficients were calculated from an application of the analytical solution of Fick's law of diffusion for adsorption in cylindrical particles. It was shown that phenol diffusion occurs via a mixed process involving the carbon surface and pores. The diffusion energy obtained was correlated with the values for the physicochemical parameters of the carbons studied. It was concluded that the mechanism of phenol adsorption was determined not only by so-called ‘π–π interactions’ and ‘donor–acceptor complex’ formation, but also by a ‘solvent effect’ balancing the influence of the two above-mentioned factors, this solvent effect being strongly dependent on the temperature.
Adsorption of Organic Molecules in Water onto Carbon Spheres Nanostructured by Air Oxidation
Authors: Inagaki Michio , Sakanishi Midori
Published: January 2004

Carbon spheres derived from phenol resin were subjected to mild oxidation in air at a temperature of 330–370°C leading to the development of micropores, i.e. structural modification on the nanometric scale. The relative ability of such spheres for removing Methylene Blue, Diquat and phenol from their aqueous solutions was determined by soaking them for 20 h in such solutions at concentrations of 2.0 × 10−2, 5.0 × 10−5 and 1.0 × 10−3 mol/l, respectively. It was possible to obtain a master curve for each adsorbate by shifting the experimental points corresponding to the relative removal measured on spheres oxidized at 330°C and 370°C along the logarithm of the oxidation time axis to those at 350°C. The master curve thus obtained demonstrated that the removal behaviour of the oxidized spheres was associated with the development of micropores in the adsorbent and also the relationship between oxidation time and temperature.
Preparation and Examination of Activated Carbons from Date Pits Impregnated with Potassium Hydroxide for the Removal of Methylene Blue from Aqueous Solutions
Authors: Banat Fawzi , Al-Asheh Sameer , Makhadmeh Leema
Published: January 2004

The effect of chemical activation on the adsorption capacity of raw date pits towards the basic dye Methylene Blue (MB) was investigated. The raw material was impregnated with 30 wt% KOH solution followed by carbonization at 600°C for 2 h and activation with CO2 at 800°C for 1 h. The adsorption capacity increased from 80.3 mg/g to 123.1 mg/g upon chemical activation. Three simplified models including the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to test the adsorption kinetics. The rates of adsorption were found to conform to pseudo-second-order kinetics with high correlation. The equilibrium results for MB adsorption on the activated carbon obtained from date pits were well fitted by the Langmuir isotherm equation.
Points of Zero Charge and Potentiometric Titrations
Authors: Zuyi Tao , Taiwei Chu
Published: January 2004

Based on the various categories of surface charge and the definitions of points of zero charge proposed by Sposito (1984, 1998), the determination of the adsorbed proton charge (σH) and the point of zero net charge (PZNPC) of insoluble oxides and layer silicates in aqueous solution was examined in detail using potentiometric titration experiments. The confusion, various interpretations and difficulties associated with points of zero charge, including the point of zero net proton charge (PZNPC), the point of zero net charge (PZNC) and the point of zero charge (PZC), were discussed and clarified. The importance of comparing potentiometric titration curves for pure insoluble oxides in the presence and absence of specific adsorption and of layer silicates with a permanent negative charge was emphasized. The dependency of expressions of points of zero charge on the model assumed and the weakness of the method of potentiometric titrations widely used for the determination of points of zero charge were discussed.
The Hydrogen Economy and Carbon Abatement – Implications and Challenges for Wind Energy
Authors: Dutton A G
Published: January 2004

Hydrogen is a leading contender to become an alternative to fossil fuel for transport and for heat and power systems. The potential for the integration of water electrolysis systems in land based and offshore wind farms is explored and compared with the conventional alternative – steam reforming of methane. Depending on the specific production technology, hydrogen can displace fossil fuels and so reduce or completely remove the emission of carbon dioxide and other pollutants. This paper examines the principal technologies for producing hydrogen and shows how the eventual choice is likely to depend as much on political and legislative factors as on economic criteria.
Mechanical Excitation of Electricity-Producing Wind Turbines at Grid Faults
Authors: Akhmatov Vladislav
Published: January 2004

A model of electricity-producing wind turbines, focusing on a detailed representation of the mechanical construction by a simplified aeroelastic code, is implemented in the simulation tool PSS/E. The model is used to investigate the mechanical excitation of the grid-connected wind turbines due to grid faults. The power grid models, of arbitrary complexity, allow an accurate response of the wind turbine generators to the grid fault. This simulates an accurate voltage profile and, hence, the electric torque affecting the mechanical construction through the shaft system. The turbine construction will be excited by the grid fault with torsional oscillations and vibrations in the shaft system. These mechanical responses are compared with the respective oscillations and vibrations occurring in the wind turbine at a safety-stop. The analysis is important because the capacities and physical size of new wind turbines are increasing significantly, so the interaction between the wind turbine mechanical construction and the power grid will affect power stability.
Guidelines for Wind Power and Wildlife in Washington State, USA
Authors: Ling Sonja , Linehan Andy
Published: January 2004

The Washington Department of Fish and Wildlife (WDFW) adopted wind power guidelines in 2002 to promote standardisation of the agency's responses to proposed wind energy projects in Washington State. While the purpose of the guidelines was to create consistency from the agency, some of the recommendations seemed overly stringent and unjustified to the wind industry. Recognising the implications of the guidelines on wind energy development in the State, the Renewable Northwest Project (RNP), along with industry members and their permitting consultants, successfully engaged the agency in a discussion to reach fair and consistent wind power guidelines. The account and methods of negotiation are detailed as an example for abating possible adverse avian and habitat environmental impact of wind farms. The three key areas of negotiation were: pre-permit environmental studies, wildlife and habitat mitigation, and an alternative fee-based mitigation option.
A Preliminary Investigation of Low-Cost SODAR Anemometry
Authors: Hayashi T. , Liu W. , Sassa K.
Published: January 2004

This preliminary research examined the applicability of Mini Doppler SODAR (MDS – sonic detection and ranging) for wind characteristics assessment of a potential wind farm. The wind characteristics obtained from the MDS were compared with those from standard anemometers on a 70 m high observation tower located near the MDS on relatively flat terrain. The wind speed and direction data recorded from the MDS were in general agreement with those from the tower at each height except for Z = 30 m. The wind speed profiles measured by these two methods at night agreed well. However, in the daytime the MDS underestimated the wind speed due to the effects of acoustic noise from surrounding activities, to turbulence caused by the wake of windbreaks and to convective instability. These results showed that the MDS might serve as useful equipment for the wind characteristics investigation after some improvement.
Solidity and Blade Number Effects on a Fixed Pitch, 50 W Horizontal Axis Wind Turbine
Authors: Duquette Matthew M. , Swanson Jessica , Visser Kenneth D.
Published: January 2004

Experimental studies were conducted on a modified Rutland 500 horizontal axis wind turbine to evaluate numerical implications of solidity and blade number on the aerodynamic performance. Wind tunnel data were acquired on the turbine with flat-plate, constant-chord blade sets and optimum-designed blade sets to compare with theoretical trends, which had indicated that increased solidity and blade number more than conventional 3-bladed designs, would yield larger power coefficients, CP. The data for the flat plate blades demonstrated power coefficient improvements as the range of solidities was increased from 7% to 27%, but did not indicate performance gains for increased blade numbers. It was also observed that larger pitch angles decreased the optimum tip speed ratio range significantly with a small (5% or less) change in maximum CP. The optimum-design 3-bladed rotors produced an increased experimental CP as solidity increased, with reduced tip speed ratio, at the optimum operating point. As blade number was increased at a constant solidity of 10% from 3 to 12 blades, aerodynamic efficiency and power sharply decreased, contrary to the numerical predictions and the flat plate experimental results. Low Reynolds numbers and wind tunnel blockage effects limit these conclusions and a full scale prototype rotor is being constructed to examine the results of the numerical and experimental studies using a side-by-side comparison with a commercially available wind turbine at the Clarkson University wind-turbine test site.
A Study of the Twisted Sweeney-Type Wind Turbine
Authors: Nemoto Yasuyuki , Anzai Ayumu , Ushiyama Izumi
Published: January 2004

The late professor Thomas E. Sweeney of Princeton University proposed the concept of vertical-axis wind turbines driven by drag/lift force in 1973. The authors fabricated Twisted-Sweeney type wind turbines, based on the Sweeney type wind turbine, to improve the performance and to enhance its external appearances. From experimental testing of this wind turbine in a wind tunnel, the following conclusions were deduced.
Characteristics of Carbon Transactions. Joint Implementation, Clean Development Mechanisms and Emission Trading in Perspective
Authors: de Coninck Heleen , van der Linden Nico
Published: January 2004

Throughout the past years, the first carbon credits – though not yet certified by the UNFCCC – have been traded. The technologies used, project size and regional preferences of carbon transactions via Joint Implementation and the Clean Development Mechanism approved under major programmes are reviewed in this paper. The current full JI and CDM project portfolio aims to reduce some 100 MtCO2-eq. This market is highly monopsonic; the buyers determine which credits are sold. The 12 JI projects are mainly implemented in Romania and Poland and constitute a diverse technology portfolio. Most of the 37 CDM projects are implemented in Latin America. Hydro and wind energy projects dominate in terms of numbers of projects. One large-scale fuel switch and one afforestation project bias the portfolio in terms of absolute CO2 reduction. Comments are made on the baseline consistency and additionality of the currently selected projects. The assessment of emissions trading programmes is more difficult than that of separate projects, because of the characteristics of an emissions trading market. Yet, depending on the starting conditions, the ET programmes vary in their success.
Strategic Aspects of Co2-Emissions Trading: Theoretical Concepts and Empirical Findings
Authors: Ehrhart Karl-Martin , Hoppe Christian , Schleich Joachim , Seifert Stefan
Published: January 2004

This paper investigates the strategic challenges for companies arising from the EU-wide greenhouse gas emission trading system (EU-ETS). Tools are suggested to help companies develop synchronised abatement and trading strategies in their dynamic decision making and facilitate overall cost-minimising behaviour. Furthermore, an EU-ETS simulation game is presented, which has recently been carried out in Germany, and which combines the advantages of a field experiment and a controlled laboratory experiment. The results of the game suggest that the proposed trading system will not automatically result in the expected cost savings. Different factors can be identified as the causes, such as specific design parameters of the EU-ETS, participants' lack of experience with a new instrument, their lack of trust in the market mechanism and risk aversion. The simulation results stress the need for companies to acquaint themselves with the rules and the range of possible strategies.
Including Investment Risk in Large-Scale Power-Market Models
Authors: Lemming Jacob , Meibom Peter
Published: January 2004

Long-term energy market models can be used to examine investments in production technologies, however, with market liberalisation it is crucial that such models include investment risks and investor behaviour. This paper analyses how the effect of investment risk on production technology selection can be included in large-scale partial equilibrium models of the power market. The analyses are divided into a part about risk measures appropriate for power market investors and a more technical part about the combination of a risk-adjustment model and a partial-equilibrium model. To illustrate the analyses quantitatively, a framework based on an iterative interaction between the equilibrium model and a separate risk-adjustment module was constructed. To illustrate the features of the proposed modelling approach we examined how uncertainty in demand and variable costs affects the optimal choice of production technologies.
Adoption and Diffusion of Decentralised Energy Conversion Technologies: The Success of Engine Co-Generation in Germany
Authors: Madlener Reinhard , Schmid Christiane
Published: January 2004

Energy market liberalisation, concerns about environmental pollution and climate change, and the dependence on fossil fuel imports render the adoption and diffusion of distributed generation technologies a field of research increasingly recognised as important. This paper contains a brief overview of both commercially available and close-to-market distributed co-generation (CHP) technologies and fields of application. It also provides a thorough investigation on the adoption and diffusion of engine-based CHP systems in the German market since 1960. The empirical analysis is mainly based on a detailed data set of nearly 5,000 such systems installed in Germany until 1998. It makes use of descriptive data analysis, net present value calculations, and micro-econometric (hazard rate) modelling. We further assess market diffusion from 1998 until today and future diffusion prospects, and discuss impacts on the development that stem from liberalisation-driven energy market transformation processes. The results show that economic considerations alone do not suffice to explain the adoption decisions taken by investors, and also present some new insights with regard to the use of hazard rate models in the context of energy conversion technology adoption.
Voluntary Agreements for CO2 Emissions Reduction: Evaluation and Perspectives
Authors: Croci Edoardo
Published: January 2004

Over the last 10 years voluntary agreements have been adopted in Europe as an environmental policy instrument to reduce CO2 emissions. These agreements have been used in accordance with the specific economic, institutional and cultural features of the Member States. The evaluation of the cases of CO2 emission reduction does not, however, provide a definitive answer regarding the effectiveness and efficiency of these agreements. This is due to a number of reasons such as the absence of reference scenarios and the fact that the targets set are often too easy to reach.

Nevertheless it is possible to determine some “rules” to design, negotiate, implement and monitor voluntary agreements according to effectiveness, efficiency and equity criteria.

Moreover a European model for voluntary agreements at the Community level and a new generation of voluntary agreements are being developed in order to overcome some of the drawbacks of the past agreements.
Interactions between the EU Emissions Trading Scheme and the UK Renewables Obligation and Energy Efficiency Commitment
Authors: Sorrell Steve
Published: January 2004

The recent agreement by European environment ministers on the ground rules for an EU Emissions Trading Scheme (EU ETS) represents a landmark in the evolution of EU climate policy. But this scheme will be introduced into a crowded ‘policy space’ within each Member State in which complex interactions between the EU ETS and existing instruments appear unavoidable. This paper explores one aspect of the problems created by the EU ETS for the UK – namely the potential interactions with the UK Renewables Obligation and the UK Energy Efficiency Commitment. Both these instruments have objectives which go beyond the least-cost abatement of carbon emissions and both utilise trading arrangements in which the trading commodity is denominated in MWh rather than tonnes of carbon. The paper explores the potential interactions between the EU ETS and the UK instruments by comparing in turn their scope, timing, objectives and operation. The coexistence of the EU ETS with the RO and EEC is shown to raise three important issues, namely target setting and double counting, double regulation of electricity and the fungibility of trading commodities. The paper concludes that the coexistence of the RO and EEC with the EU ETS is both possible and justifiable, but more attention should be paid to the non-CO2 objectives of each instrument.
Technical Efficiency Measures as a Tool for Energy Benchmarking in Industry?
Authors: Couder Johan , Verbruggen Aviel
Published: January 2004

Energy benchmarking is a practical management tool to evaluate and improve the energy performance of an industrial firm, possibly revealing considerable potentials for energy savings and for reduction of emissions to the atmosphere and biosphere. Existing energy metrics used for energy benchmarking however are strictly limited to measuring energy efficiency, completely disregarding positive or negative effects energy savings may have on other environmental pressures (use of depletable resources other than energy, emissions of pollutants, effluents or waste). We therefore propose investigating the use of technical efficiency measures as energy benchmarking tools. Technical efficiency is explored from both an engineering and a micro-economic approach, although we limit our discussion to the non-parametric mathematical programming performance measures. Particular attention is given to the inclusion of undesirable outputs or ‘bads' in the existing performance measures. We conclude with a cursory review of empirical research done in the field of environmental performance indicators (EPIs), mainly in the sector of electricity generation and pulp and paper mills.