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Variations of permanent and pH-dependent charges of soil clays subjected to thermal and chemical treatments were studied. The permanent charge was considerably reduced either on heating samples at 400°C or on acid treatment. A strong hysteresis of the permanent charge occurred in the heated samples treated with NaOH. The decrease in permanent charge after attack with HCl was due to vermiculite decomposition. The different behaviour of the pH-dependent charge was attributed to the structural changes which different treatments can give rise on the interlayer materials.

Two groups of 18 healthy adults, chosen from a risk population, were vaccinated against hepatitis B virus with French (Hevac B, Pasteur) or American (HB-VAX, MSD) vaccine; immunological and biochemical parameters (HBsAb titers, Ig, IgM-rheumatoid factor (IgM-RF) levels, autologous mixed lymphocyte reaction (AMLR), T4/T8 ratio, lymphocyte migration inhibition test (LMIT) with specific antigen and transaminase levels) were compared at preselected time intervals. The vaccines were found to be clinically safe, as documented by the absence of demonstrable side effects and changes in serum transaminase levels. The positivity of the LMIT test demonstrated an early immunization on day 45 in all subjects tested, along with a marked reduction in AMLR, independent of the vaccine used. A slightly higher, though not statistically significant, percentage of seroconversion was observed for the Pasteur vaccine. This same preparation induced a significant increase in the main Ig classes and in Ig;-RF levels on day 45. This data indicates that aspecific modification of the immune system occur to a greater extent with Hevac B, presumably for its lower degree of purification. Thus, despite the slightly lower efficacy, the HB-VAX might be the preparation of choice in subjects with immunological disturbances.

Mouse RBC (M) rosettes were investigated on lymphocytes from peripheral blood (PB) and various tissues in twenty patients with chronic lymphocytic leukaemia and one with follicular lymphoma. In all cases studied, the percentage of M rosettes was significantly higher in PB (median 64%) than in bone marrow (median 15%) and lymph node (median 12%). These differences were statistically significant (P less than 0.01). The possibility that these differences were related to technical factors was ruled out by a number of control procedures. It is suggested that the different expression of M rosette formation reflects the property which determines whether a lymphocyte enters the peripheral blood or remains fixed in the tissues.

The Sardinian population in many aspects differs from other Caucasoid populations, particularly for its degree of homogeneity. For this reason we have studied 50 adult Sardinian patients with celiac disease (CD) and 50 control healthy Sardinian individuals by RFLP analysis and by extensive oligotyping for 17 HLA-DPB1, 8-DQB1 and 9-DQA1 alleles, and established their -DPB1 alleles and -DQB1 -DQA1 genotypes. The heterodimer HLA-DQB1*0201/-DQA1*0501, present in 96% of our patients, is strongly associated with CD susceptibility, confirming published reports. On the other hand we found in 11 of 50 probands (22%) the presence of the allele -DQB1*0502/DQA1*0102. This genotype is extremely rare in other Caucasian populations and appears to confer limited protection in CD Sardinian patients.

In most telecom applications, optical band-pass filters must ensure flat-top response. Different filter synthesis techniques have been proposed in the literature, including lattice filters [1] and cascaded interferometers with suitably chosen symmetries [2,3]. All these methods require in general the possibility to choose freely the splitting ratios of the power splitters, which (at least in theory) is usually not too hard to achieve with directional couplers. On the other hand, Multimode Interferometers (MMIs) are an attractive alternative to directional couplers, thanks to their more relaxed tolerances to fabrication errors and their relatively broadband operation. Nevertheless, they have the drawback that only a limited discrete set of five splitting ratios is achievable with a single MMI, namely 50:50, 85:15, 73:27, and their inverse ratios [4]. This issue clearly limits their use in designing flat-top interferometric filters. In this work we show for the first time that is possible to design 4-stage flat-top interferometers using four 50:50 MMIs (i.e. two double MMIs [5]) and three 85:15 MMI splitters. Like in Ref. [3], the design approach is based on the representation of the system on the Bloch sphere for two-level systems. Flat-top interleavers with different free spectral ranges have been designed and fabricated on the standard micron-scale silicon photonics platform of VTT, based on 3 µm thick rib and strip waveguides. Two main types of layouts have been explored: a more straightforward one where all components are collinear as shown in Fig. 1(a), and a more compact one shown in Fig.1(b), where the components have been folded in a spiral shape. All interleavers have been designed for TE polarization, and they work fine in a wavelength range comparable with the 100 nm bandwidth of the MMI splitters. Most designs show in-band extinction exceeding 15 dB. Fabrication imperfections and non-ideal behaviour of both bends and MMIs led to reduced extinction compared to simulations and, interestingly, also to clear differences in the spectra corresponding to different input ports, as clearly shown in Fig. 1(c). The in-band losses of the most central channels did not exceed 1.5 dB compared to the fiber-to-fiber losses measured with the reference straight waveguide.

Thanks to nanostructurization process lenses have very small sizes, flat surface andvery short working distances. We present lensed fibre system with nanostructured GRIN whichimproves coupling efficiency.