Quantitative measurements are made of the adsorption of benzidine and aniline from aqueous hydrochloride solutions by Na-, Li-, and Ca-montmorillonite and of the displaced inorganic cations. From these data, the ionic states of the adsorbed organic species are determined. Under conditions of controlled pH, the adsorption of benzidine increases as the pH increases, and involves mainly divalent species at pH<3·2, and increasing proportions of monovalent and neutral species at pH> 3·2. With aniline, monovalent and neutral species are adsorbed, and hydrogen ions also appear to participate in the reactions.

Color developments of benzidine and aniline complexes of montmorillonite and hectorite are considered qualitatively in relation to the adsorption data, to various experimental conditions including the nature of the inorganic exchangeable cations, the pH, and the presence or absence of oxygen in the system, and to relevant previous work. It is hypothesized that the blue color of the benzidine complex is due to semiquinone formation by oxidation on montmorillonite by the clay itself, and on hectorite by dissolved oxygen or H2O2, and that the yellow color under acid conditions arises from reversible formation of quinoidal cations from semiquinones. The color developments of the aniline complex are due probably to oxidation of aniline by atmospheric oxygen.

Systematic reviews carried out by Cochrane Collaboration (an international network of researchers belonging to this independent, not-for-profit organization) are recognized worldwide as the highest standard in evidence-based healthcare. The main reason is that Cochrane reviews follow a common and specific methodology to limit bias and random error. In this issue, we highlight the most important methodological features of Cochrane reviews, also reporting details on the editorial process to publish the review in the Cochrane Library.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

A 54-year-old man complained of severe throat pain and showed subglottic oedema on fibre-optic endoscopy with a distinctly narrowed subglottic space on anteroposterior radiography of the neck and dense linear opacity at the level of the cricoid cartilage on lateral plain radiography. These findings suggested a foreign body just posterior to the cricopharyngeus, but a computed tomography (CT) scan demonstrated a dense calcified ridge on the posterior lamina of the cricoid cartilage but no foreign body.

The patient improved symptomatically with systemic antibiotics and topical steroids, and gastrointestinal endoscopy did not detect any foreign body. This is a rare case of vertical ossification of the cricoid lamina masquerading as a foreign body.

Background. Depression is a remitting but recurring disease. However, there is a paucity of prospectively recorded data on the course of depression after recovery.

Method. A multi-centre prospective serial follow-up study of an inception cohort of hitherto untreated unipolar major depression (N=95) for 6 years. We report the time to recurrence after recovery from the index depressive episode and their predictors.

Results. The cumulative probability of remaining well without subthreshold symptoms was 57% (95% CI, 46 to 68%) at 1 year, 47% (95% CI, 36 to 58%) at 2 years and 35% (95% CI, 23 to 47%) at 5 years. The same without full relapse was 79% (95% CI, 70 to 88%) at 1 year, 70% (95% CI, 60 to 80%) at 2 years and 58% (95% CI, 46 to 70%) at 5 years. The median duration of well-interval from the end of the index episode to the beginning of the subthreshold episode was 19·0 months (95% CI, 2·4 to 35·7), and that to the end of the full episode was over 6 years. Residual symptoms at time of recovery predicted earlier recurrence.

Conclusions. The median length of the well-interval was much longer than previously reported in studies employing similar definitions but dealing with a more severe spectrum of patients. However, the sobering fact remains that less than half of the patients can expect to remain virtually symptom-free for 2 years or more after recovery from the depressive episode.

Background. Two new screening scales for psychological distress, the K6 and K10, have been developed but their relative efficiency has not been evaluated in comparison with existing scales.

Method. The Australian National Survey of Mental Health and Well-Being, a nationally representative household survey, administered the WHO Composite International Diagnostic Interview (CIDI) to assess 30-day DSM-IV disorders. The K6 and K10 were also administered along with the General Health Questionnaire (GHQ-12), the current de facto standard of mental health screening. Performance of the three screening scales in detecting CIDI/DSM-IV mood and anxiety disorders was assessed by calculating the areas under receiver operating characteristic curves (AUCs). Stratum-Specific Likelihood Ratios (SSLRs) were computed to help produce individual-level predicted probabilities of being a case from screening scale scores in other samples.

Results. The K10 was marginally better than the K6 in screening for CIDI/DSM-IV mood and anxiety disorders (K10 AUC: 0·90, 95%CI: 0·89–0·91 versus K6 AUC: 0·89, 95%CI: 0·88–0·90), while both were significantly better than the GHQ-12 (AUC: 0·80, 95%CI: 0·78–0·82). The SSLRs of the K10 and K6 were more informative in ruling in or out the target disorders than those of the GHQ-12 at both ends of the population spectrum. The K6 was more robust than the K10 to subsample variation.

Conclusions. While the K10 might outperform the K6 in screening for severe disorders, the K6 is preferred in screening for any DSM-IV mood or anxiety disorder because of its brevity and consistency across subsamples. Precision of individual-level prediction is greatly improved by using polychotomous rather than dichotomous classification.

Background. In evidence-based medicine, stratum-specific likelihood ratios (SSLRs) are now being increasingly recognized as a more convenient and generalizable method to interpret diagnostic information than an optimal cut-off and its associated sensitivity and specificity. We previously examined the SSLRs of the General Health Questionnaire (GHQ) in primary care settings. The present paper aims to examine if these SSLRs are generalizable to the community settings.

Methods. The Composite International Diagnostic Interview (CIDI) and the GHQ were administered on a representative sample of the Australian population in the Australian National Survey of Mental Health and Well-Being. We first compared the SSLRs of GHQ in urban Australia with the estimates that we had previously obtained from the developed urban centres in the WHO Psychological Problems in General Health Care study. If the SSLRs in the community were found to differ significantly from those in the primary care, we sought for explanatory variables.

Results. The SSLRs in urban Australia and in the urban centres in the WHO study were significantly different for three out of the six strata. When we limited the sample to those with physical problems who visited a health professional, however, the SSLRs in the Australian study were strikingly close to those observed for primary care settings.

Conclusions. Different sets of SSLRs apply to primary care and general population samples. For general population surveys in developed countries, the results of the Australian National Survey represent the currently available best estimates. For developing countries or rural areas, the results are less definitive and an investigator may wish to conduct a pilot study.

A new technology for separating and recovering iron and zinc from EAF exhaust gases is proposed. The process is composed of a coke bed filter and a new type of zinc condenser. Iron and slag components in the exhaust gas are collected in the coke bed filter. In this paper, the theoretical background and numerical analysis of the characteristics of the coke bed filter are introduced, and the experimental results concerning the collection of iron and slag components in a bench-scale coke bed filter are reported.