Use of sodium polyphosphates with different linear lengths in the production of spreadable processed cheese.

The objective of this study was to describe the dependence of textural properties (hardness, cohesiveness, and relative adhesiveness) of processed cheese spreads on the proportion of disodium phosphate (DSP), tetrasodium diphosphate (TSPP), and sodium salts of polyphosphate in ternary mixtures of emulsifying salts. Sodium salts of polyphosphate with different mean lengths (n ≈ 5, 9, 13, 20, and 28) were used. Pentasodium triphosphate (PSTP) was used instead of TSPP in the second part of the study. Products with and without pH adjustment were tested (the target pH value was 5.60-5.80). Textural properties of the processed cheese were observed after 2, 9, and 30 d of storage at 6°C. Hardness of the processed cheese with a low content of polyphosphate increased at a specific DSP:TSPP ratio (~1:1 to 3:4). This trend was the same for all the polyphosphates used; only the absolute values of texture parameters were different. The same trends were observed in the ternary mixtures with PSTP, showing lower final values of hardness compared with samples containing TSPP. Hardness and cohesiveness decreased and relative adhesiveness increased in the samples with increased pH values and vice versa; the main trend remained unchanged.

Evaluating auditory perception and communication demands required to carry out work tasks and complimentary hearing resources and skills for older workers with hearing loss.

For older workers with acquired hearing loss, this loss as well as the changing nature of work and the workforce, may lead to difficulties and disadvantages in obtaining and maintaining employment. Currently there are very few instruments that can assist workplaces, employers and workers to prepare for older workers with hearing loss or with the evaluation of auditory perception demands of work, especially those relevant to communication, and safety sensitive workplaces that require high levels of communication. This paper introduces key theoretical considerations that informed the development of a new framework, The Audiologic Ergonomic (AE) Framework to guide audiologists, work rehabilitation professionals and workers in developing tools to support the identification and evaluation of auditory perception demands in the workplace, the challenges to communication and the subsequent productivity and safety in the performance of work duties by older workers with hearing loss. The theoretical concepts underpinning this framework are discussed along with next steps in developing tools such as the Canadian Hearing Demands Tool (C-HearD Tool) in advancing approaches to evaluate auditory perception and communication demands in the workplace.

Enhanced dechlorination of chlorobenzene and in situ dry sorption of resultant Cl-compounds by CaO and Na2CO3 sorbent beds incorporated with Fe2O3.

The dechlorination of C(6)H(5)Cl and the in situ dry sorption of Cl-compounds produced by C(6)H(5)Cl decomposition in an alkaline sorbent of CaO or Na(2)CO(3) incorporated with Fe(2)O(3) were studied. A sample gas containing C(6)H(5)Cl at an initial concentration of 500 ppm balanced by either N(2), O(2) (5%)-N(2) or H(2)O (10%)-N(2) carrier gas was introduced into a lab-scale quartz tube reactor where CaO or Na(2)CO(3) sorbent was packed with Fe(2)O(3). Subsequently, the effect of Fe(2)O(3) addition to CaO or Na(2)CO(3) on the removal of C(6)H(5)Cl, achieved by the decomposition of C(6)H(5)Cl as well as the dry sorption of Cl-compounds produced by C(6)H(5)Cl decomposition, was investigated. It was found that the decomposition of C(6)H(5)Cl in CaO or Na(2)CO(3) sorbent bed incorporated with Fe(2)O(3) occurred in the lower temperatures, compared to the case when only CaO or Na(2)CO(3) sorbent bed was used. Thus, Fe(2)O(3) was found to play a catalytic role in the oxidative decomposition of C(6)H(5)Cl. Further, the decomposition of C(6)H(5)Cl in a bed containing only Fe(2)O(3) was promoted by the presence of O(2) and H(2)O in the reaction atmosphere. Moreover, a higher amount of Cl was absorbed in the combined CaO/Fe(2)O(3) and Na(2)CO(3)/Fe(2)O(3) beds, compared to the absorption of Cl-compounds in only CaO or Na(2)CO(3) sorbent bed. Finally, the comparison of CaO and Na(2)CO(3) sorbents showed that the decomposition of C(6)H(5)Cl and the in situ dry sorption of the resultant Cl-compounds in the combined Na(2)CO(3) and Fe(2)O(3) beds were higher than those in the combined CaO and Fe(2)O(3) beds.

Study on reaction kinetics and selective precipitation of Cu, Zn, Ni and Sn with H2S in single-metal and multi-metal systems.

Determination of reaction kinetics and selective precipitation of Cu, Zn, Ni and Sn with H(2)S in single-metal and multi-metal systems were studied to develop a process of metal recovery from plating wastewater. As samples, single-metal model wastewaters containing Cu, Sn, Zn or Ni, and multi-metal model wastewater containing Cu-Zn-Ni or Sn-Zn mixtures were used. In both single-metal and multi-metal systems, the pH value was precisely controlled at a value of 1.5 for CuS and SnS precipitation, 4.5 for ZnS precipitation and 6.5-7.0 for NiS precipitation. Subsequently, the sulfidation of Cu, Sn, Zn and Ni was evaluated. It was found that an amount of H(2)S equimolar to a given metal was sufficient to achieve almost complete precipitation of the particular metal. Further, the selectivity of metal precipitation was found to be higher than 95% in the Cu-Zn-Ni multi-metal system and higher than 91% in the Sn-Zn system. It was also found that the sulfidation reaction proceeded in accordance with Higbie's penetration theory and reaction rate constants and mass-transfer coefficients under various experimental conditions were determined. Finally, the reaction rate constants obtained in single-metal and multi-metal systems were found to be almost the same indicating that the precipitation of a particular metal was not significantly affected by the presence of other components.

Sulfidation treatment of molten incineration fly ashes with Na2S for zinc, lead and copper resource recovery.

The present study focuses on the conversion of heavy metals involved in molten incineration fly ashes to metal sulfides which could be thereafter separated by flotation. The sulfidation treatment was carried out for five molten incineration fly ashes (Fly ash-A to Fly ash-E) by contacting each fly ash with Na(2)S solution for a period of 10 min to 6h. The initial molar ratio of S(2-) to Me(2+) was adjusted to 1.20. The conversion of heavy metals to metal sulfides was evaluated by measuring the S(2-) residual concentrations using an ion selective electrode. The formation of metal sulfides was studied by XRD and SEM-EDS analyses. In the case of Fly ash-A to Fly ash-D, more than 79% of heavy metals of zinc, lead and copper was converted to metal sulfides within the contacting period of 0.5h owing to a fast conversion of metal chlorides to metal sulfides. By contrast, the conversion of about 35% was achieved for Fly ash-E within the same contacting period, which was attributed to a high content of metal oxides. Further, the S(2-) to Me(2+) molar ratio was reduced to 1.00 to minimize Na(2)S consumption and the conversions obtained within the contacting period of 0.5h varied from 76% for Fly ash-D to 91% for Fly ash-C. Finally, soluble salts such as NaCl and KCl were removed during the sulfidation treatment, which brought about a significant enrichment in metals content by a factor varying from 1.5 for Fly ash-D to 4.9 for Fly ash-A.

Sulfidation treatment of copper-containing plating sludge towards copper resource recovery.

The present study is concerned with the sulfidation treatment of copper-containing plating sludge towards copper resource recovery by flotation of copper sulfide from treated sludge. The sulfidation treatment was carried out by contacting simulated or real copper plating sludge with Na(2)S solution for a period of 5 min to 24 h. The initial molar ratio of S(2-) to Cu(2+) (S(2-) to Me(2+) in the case of real sludge) was adjusted to 1.00, 1.25 or 1.50, while the solid to liquid ratio was set at 1:50. As a result, it was found that copper compounds were converted to various copper sulfides within the first 5 min. In the case of simulated copper sludge, CuS was identified as the main sulfidation product at the molar ratio of S(2-) to Cu(2+) of 1.00, while Cu(7)S(4) (Roxbyite) was mainly found at the molar ratios of S(2-) to Cu(2+) of 1.50 and 1.25. Based on the measurements of oxidation-reduction potential, the formation of either CuS or Cu(7)S(4) at different S(2-) to Cu(2+) molar ratios was attributed to the changes in the oxidation-reduction potential. By contrast, in the case of sulfidation treatment of real copper sludge, CuS was predominantly formed, irrespective of S(2-) to Me(2+) molar ratio.

Sulfidation of zinc plating sludge with Na2S for zinc resource recovery.

A high amount of zinc disposed in the landfill sites as a mixed-metal plating sludge represents a valuable zinc source. To recover zinc from the plating sludge, a sulfidation treatment is proposed in this study, while it is assumed that ZnS formed could be separated by flotation. The sulfidation treatment was conducted by contacting simulated zinc plating sludge with Na(2)S solution at S(2-) to Zn(2+) molar ratio of 1.5 for a period of 1-48 h, while changing the solid to liquid (S:L) ratio from 0.25:50 to 1.00:50. The conversion of zinc compounds to ZnS was determined based on the consumption of sulfide ions. The reaction products formed by the sulfidation of zinc were identified by X-ray diffraction (XRD). As a result, it was found that the conversion of zinc compounds to ZnS increased with an increase in S:L ratio. A maximum conversion of 0.809 was obtained at an S:L ratio of 1.00:50 after 48 h. However, when the zinc sludge treated at S:L ratio of 1.00:50 for 48 h was subjected to XRD analyses, only ZnS was identified in the treated zinc sludge. The result suggested that the rest of zinc sludge remained unreacted inside the agglomerates of ZnS. The formation behavior of ZnS was predicted by Elovich equation, which was found to describe the system satisfactorily indicating the heterogeneous nature of the sludge.

Recurrent atrial electrode displacement complicating a single lead VDD pacing system.

We describe an unusual complication of single-lead VDD pacing: recurrent advancement of the atrial bipole into the right ventricle. As a consequence, the patient experienced symptomatic pacemaker-mediated tachycardia and underwent two revision operations to achieve adequate fixation of the lead.

Inappropriate rate change in minute ventilation rate responsive pacemakers due to interference by cardiac monitors.

Observations of inappropriate rate increase in five patients with minute ventilation rate responsive implanted pacemakers (Telectronics Meta) are reported. Pacing rate increases were observed immediately upon connection of the resting patients to two brands of widely used cardiac monitors, and one commonly used echocardiograph. In some circumstances, the rate increase remained until monitor disconnection; in others the rate increase was transient, lasting and 20 seconds. A hardware thoracic resistance variation simulator was constructed and connected to one of the pacemakers to test sensitivity to rate modifying interference from external sources. This demonstrated that the sensitivity to interference is dependent upon the frequency of the interfering signal and is highest in the range 10-60 kHz, that peak currents as low as 10 microA can cause maximum rate increase, and that the signals injected into patients by several cardiac monitors, for purposes of lead-off detection or respiratory monitoring, fall into the frequency range at which the pacemaker is most susceptible to interference.

Idiopathic right ventricular tachycardia: electrophysiology and response to catheter ablation.

BACKGROUND: Ventricular tachycardia (VT) originating in the right ventricle may be seen in the absence of structural heart disease. Although this is thought to be associated with a benign course, it may cause intolerable symptoms and be difficult to control with antiarrhythmic drugs. AIMS: To assess the value of radiofrequency ablation of right ventricular tachycardia and to characterise the clinical and electrophysiologic features predictive of successful ablation. METHODS: Nine patients (aged 20-49 years) with clinical VT underwent cardiac mapping which localised the site of origin of VT in the right ventricle. At least three separate areas of VT origin were identified in these patients. Ablation of VT was defined as suppression of VT at the time of hospital discharge. RESULTS: Five patients had successful ablation of the tachycardia focus with long term suppression of the arrhythmia. Patients with successful ablation were characterised by inability to induce VT with extrastimuli, a distinct VT morphology with a rS pattern in lead 1, right axis deviation, facilitation of VT with isoprenaline and site of origin in the lateral outflow tract. During VT, an earlier site of presystolic activation was found in successful patients compared with unsuccessful ablations. Right ventricular tachycardia in patients without structural heart disease is a heterogeneous disorder with varied clinical and electrophysiologic features. Successful ablation of VT may be predicted by consideration of these variables.

Transesophageal echocardiography before and during direct current cardioversion of atrial fibrillation: evidence for "atrial stunning" as a mechanism of thromboembolic complications.

OBJECTIVES: The purpose of this study was to evaluate the usefulness of transesophageal echocardiography before electrical cardioversion in patients with atrial fibrillation and to determine the mechanism of thromboembolism after cardioversion. BACKGROUND: Thromboembolic complications after electrical cardioversion of atrial fibrillation have been attributed to the dislodgment of preexistent left atrial thrombus during the resumption of atrial contraction. Transesophageal echocardiography has been proposed as a method of screening patients for left atrial thrombus before cardioversion. METHODS: Seventy transesophageal echocardiographic studies were performed in 66 patients, predominantly with nonvalvular atrial fibrillation, before direct current cardioversion. In addition, transesophageal echocardiography was performed during the cardioversion procedure in 15 patients and immediately after in 1 patient. RESULTS: Left atrial thrombus was detected in one patient (1.4%), and cardioversion was cancelled. Thromboembolic complications occurred in 4 patients, none of whom had evidence of left atrial thrombus before cardioversion. Within 10 s of successful cardioversion, left atrial spontaneous echo contrast appeared in five patients, increased in one patient and was unchanged in nine patients. Patients with new or increased spontaneous echo contrast had more impaired atrial contraction and slower initial heart rates after cardioversion than those without. Left ventricular contraction was also impaired transiently by cardioversion. CONCLUSIONS: Transesophageal echocardiographic detection of left atrial thrombus before direct current cardioversion is important but infrequent in patients with predominantly nonvalvular atrial fibrillation. The occurrence of thromboembolic complications in the absence of demonstrable left atrial thrombus and the new development of spontaneous echo contrast in association with the transient atrial dysfunction ("stunning") caused by cardioversion suggest that cardioversion may promote new thrombus formation, in which case all patients should receive full anticoagulant therapy at the time of cardioversion.

Prognostic implications of loss of late potentials following acute myocardial infarction.

The prognosis of patients following myocardial infarction is adversely affected by the finding of late potentials at the time of hospital discharge. Loss of late potentials has been previously reported during serial testing during the first year after infarction, but it is not known whether such patients remain at risk of arrhythmic events. This study prospectively followed 243 patients after myocardial infarction. Late potentials were observed in 92 patients (group I) at the time of hospital discharge. Of these patients, 23 no longer had late potentials at 6-week follow-up and 8 had had an arrhythmic event (sudden death or ventricular tachycardia). In patients with loss of late potentials, overall QRS duration had decreased from 109 +/- 11 msec at discharge to 104 +/- 11 msec (P < 0.01), terminal QRS voltage rose from 15 +/- 4 microV to 31 +/- 9 microV (P = 0.001), and late potential duration fell from 42 +/- 6 msec to 28 +/- 6 msec (P = 0.001) at the 6-week study. Predictors of loss of late potentials were: initial duration of the QRS duration (P < 0.001) and terminal voltage (P < 0.005); non-Q wave infarction (P < 0.001); and being a male (P < 0.05). After the 6-week assessment, 11 additional arrhythmic events occurred during median follow-up of 31 months. The risk of arrhythmic events was similar in patients with loss of late potentials and those who retained late potentials in group I (9% vs 11%, P = NS) but significantly greater than patients with no late potentials at discharge (group II, 2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmogenic right ventricular dysplasia.

A 23-year-old man presented with recurrent exercise-induced ventricular tachycardia (VT), complicated by systemic embolisation. Catecholamine--sensitive VT was reproduced on exercise testing and programmed electrical stimulation, displaying features suggestive of enhanced automaticity as well as re-entry. Both 2D-echocardiography and gated heart pool scan showed localised dyskinetic bulging in the right ventricle. A diagnosis of arrhythmogenic right ventricular dysplasia was made. This condition should be excluded in all young patients with otherwise unexplained ventricular arrhythmias.