CLEANING AND PREVENTION OF INORGANIC DEPOSITS IN PLATE HEAT EXCHANGERS USING PULSATING CURRENT

Fouling of heat exchangers is a major problem in many industrial processes. The higher temperature of the heat exchange surface compared with the liquid containing precipitable compounds causes the formation of inorganic deposits. Removing the deposits on plate heat exchangers is most often carried out by high-pressure cleaning. This is a laborious task and often increases the corrosion rate of the plates by increasing the roughness of the cleaned surface. This study presents an electrochemical method to clean heat exchange surfaces fouled by deposits and to prevent formation of deposits. This method utilizes pulsating current to polarize heat exchange surfaces with periodic anodic and cathodic DC current. The shape of the pulse and the current density are adjusted to maximize the deposit removal rate, thus minimizing plate corrosion. The optimal pulsating current depends on the material of the heat exchange surface, as well as the composition of the deposits and the solution. For cleaning, the current densities and the frequency of the current pulse are typically higher than those used for preventing deposition. Pulsating current can effectively remove deposits with low solubility, such as TiO2 on titanium heat exchange plates or dense gypsum deposits on stainless steel plates. For cleaning titanium, the cathodic pulse and formation of hydrogen is more essential than in the cleaning of stainless steels. However, the risk of corrosion limits the use of high current densities. Experiments have until now been carried out mainly in the laboratory, though industrial pilot cleaning equipment has also been constructed. An application has already been submitted to patent the method

A prospective seroepidemiological study of human herpesvirus-8 infection and the risk of multiple myeloma

Presence of the Human Herpesvirus 8 (HHV8) genome has been reported in the bone marrow of multiple myeloma (MM) patients. So far, serological studies of HHV8 and MM have been inconsistent but have not included prospective epidemiological studies. We evaluated whether HHV8 infection is associated with increased risk for MM in a prospective population-based study of 39 000 Finnish subjects who donated serum samples in the period 1968–72. Serum samples from 47 subjects who developed MM during a 23-year follow-up and 224 age, area of residence and sex-matched subjects who remained healthy over a similar follow-up period were evaluated for HHV8 antibodies at enrolment, as assayed both with an immunofluorescence assay (IFA) for lytic and latent HHV8 antigens and by Western blot (WB) with three recombinant HHV8 proteins (ORFs 65, 73 and K8.1A). HHV8 seropositivity for at least one HHV8 protein on WB was found in 7% of the Finnish population and was not associated with the risk of developing MM (Relative Risk (RR) = 0.89, Confidence Interval (CI): 0.25–3.25). HHV8 seropositivity for lytic and latent antigens in the IFA was found in 16% and 0.4% of the Finnish population and tended to associate with risk of MM (RR = 2.02, CI: 0.94–4.33 and RR = 10.00, CI: 0.91–110.29, respectively). In conclusion, no statistically significant evidence for an association between HHV8 infection and the risk of future MM was found. © 2001 Cancer Research Campaign http://www.bjcancer.co

Increased target volume and hydrogen content in [11C]CH4 production

Introduction High starting radioactivity is usually advantageous for producing radiopharmaceuticals with high specific radioactivity. However, the [11C]CH4 yields from N2-H2 gas target fall short from theoretical amounts, as calculated from the cross section for the well-known 14N(p,α)11C nuclear reaction1. The beneficial effect of increased target chamber temperature on [11C]CH4 yields has recently been brought forward by us2 and others3. In addition to the temperature effect, our attention has also been on the hydrogen content factor. This study intends to examine the N2-H2 target performance in a substantially larger target chamber and at higher temperatures than our setup before and compare the results to the existing data. Materials and Methods Aluminium bodied custom design target chamber is used in fixed 17 MeV proton beam irradiations. Target chamber is equipped with heating elements and cooling circuit for temperature control. In addition to the target chamber body temperature, the target gas loading pressure and irradiation current can be varied. The irradiation product is collected into an ad-sorbent trap that was immersed in a liquid argon cooling bath within a dose calibrator. Results and Conclusion Pursued data will show [11C]CH4 saturation yields (Ysat [GBq/µA]) at different irradiation and target parameters

Serum ceruloplasmin and the risk of cancer in Finland.

The relationship between serum ceruloplasmin level and cancer incidence was investigated in a case-control study nested within a longitudinal study of 39,268 Finns participating in the Social Insurance Institution's Mobile Clinic Health Examination Survey carried out in 1968-1972. During a median follow-up of 8 years, 766 cancer cases were identified. Ceruloplasmin levels were determined from stored serum samples collected at the baseline from these cancer cases and from two matched controls per case. The overall incidence of cancer was positively associated with serum ceruloplasmin level. The association was strongest for lung cancer and other cancers related to smoking and, consequently, in males. The smoking-adjusted relative risk of lung cancer among men was 4.3 (95% confidence interval (CI) = 1.8-10.6) in the highest quintile of serum ceruloplasmin as compared with that in the lowest quintile. The corresponding relative risks for cancers related to smoking combined, and for cancers not related to smoking were 3.9 (CI = 1.9-8.4) and 0.9 (CI = 0.6-1.5), respectively. The elevated risk of lung cancer at high concentrations of serum ceruloplasmin persisted after further adjustment for several potential confounding factors such as serum levels of vitamins A and E and selenium. The risk was stronger during the first 6 years of follow-up than later, and strongest during the first 2 years. The most likely explanation of the present results thus is that high serum ceruloplasmin levels in lung cancer are mainly due to occult cancer

Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts

BACKGROUND: The magnitude of the association between Helicobacter pylori and incidence of gastric cancer is unclear. H pylori infection and the circulating antibody response can be lost with development of cancer; thus retrospective studies are subject to bias resulting from classifi- cation of cases as H pylori negative when they were infected in the past. AIMS: To combine data from all case control studies nested within prospective cohorts to assess more reliably the relative risk of gastric cancer associated with H pylori infection.To investigate variation in relative risk by age, sex, cancer type and subsite, and interval between blood sampling and cancer diagnosis. METHODS: Studies were eligible if blood samples for H pylori serology were collected before diagnosis of gastric cancer in cases. Identified published studies and two unpublished studies were included. Individual subject data were obtained for each. Matched odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated for the association between H pylori and gastric cancer. RESULTS: Twelve studies with 1228 gastric cancer cases were considered. The association with H pylori was restricted to noncardia cancers (OR 3.0; 95% CI 2.3–3.8) and was stronger when blood samples for H pylori serology were collected 10+ years before cancer diagnosis (5.9; 3.4–10.3). H pylori infection was not associated with an altered overall risk of cardia cancer (1.0; 0.7–1.4). CONCLUSIONS: These results suggest that 5.9 is the best estimate of the relative risk of non-cardia cancer associated with H pylori infection and that H pylori does not increase the risk of cardia cancer. They also support the idea that when H pylori status is assessed close to cancer diagnosis, the magnitude of the non-cardia association may be underestimated

Analysis of H-3, Cl-36, Ba-133, Cs-134 and Na-22 from synthetic granitic groundwater : an in situ through diffusion experiment at ONKALO

A method for analyzing H-3, Cl-36, Na-22, Ba-133 and Cs-134 from simulated groundwater (SGW) samples was introduced. Gamma emitting radionuclides Na-22, Ba-133 and Cs-134 were measured by using an HPGe-detector. Beta emitting H-3 and Cl-36 were separated from gamma emitting Na-22, Ba-133 and Cs-134. AgCl precipitation was used for the separation of Cl-36 from SGW samples with yields of 98 +/- 2%. H-3 was separated by distillation with recoveries of 97 +/- 3%. This method was used for the determination of activity concentrations of H-3, Cl-36, Na-22, Ba-133 and Cs-134 in SGW samples collected from an in situ through diffusion experiment.Peer reviewe

Personal stigma and use of mental health services among people with depression in a general population in Finland

Background - A minority of people suffering from depression seek professional help for themselves. Stigmatizing attitudes are assumed to be one of the major barriers to help seeking but there is only limited evidence of this in large general population data sets. The aim of this study was to analyze the associations between mental health attitude statements and depression and their links to actual use of mental health services among those with depression. Methods - We used a large cross-sectional data set from a Finnish population survey (N = 5160). Attitudes were measured by scales which measured the belief that people with depression are responsible for their illness and their recovery and attitudes towards antidepressants. Desire for social distance was measured by a scale and depression with the Composite International Diagnostic Interview Short Form (CIDI-SF) instrument. Use of mental health services was measured by self-report. Results - On the social discrimination scale, people with depression showed more social tolerance towards people with mental problems. They also carried more positive views about antidepressants. Among those with depression, users of mental health services, as compared to non-users, carried less desire for social distance to people with mental health problems and more positive views about the effects of antidepressants. More severe depression predicted more active use of services. Conclusions - Although stronger discriminative intentions can reduce the use of mental health services, this does not necessarily prevent professional service use if depression is serious and views about antidepressant medication are realistic.peerReviewe