Hydrolysis of titanium alkoxide and effects of hydrolytic polycondensation parameters

Titanium alkoxides hydrolyse vigorously with water producing polycondensates whose equivalent oxide content varies from 70% to over 90%. This variation reflects the average molecular size and the nature of the terminal bonds. Hydrolysis conditions also affect the molecular and particle morphologies modifying the crystallization and sintering behaviour of oxide materials derived from polycondensates. It is also possible to form clear polymer solutions under excess water hydrolysis with the addition of certain acids. Investigations show that there is a window in the acid concentration which provides long-term solution stability. The gels formed from these clear solutions shrink in their liquor under certain conditions and the introduction of hydrogen peroxide into the liquor (surrounding the gel) causes vigorous gel shrinkage.     

Features of a Scan and Clock Resource chip for providing access to board-level test functions

The architecture and some of the specific features of a Scan and Clock Resource (SCR) chip are described. This chip is currently being used in a high-end workstation product to provide access to the testability features of the individual chips and/or printed circuit boards. Using a board-level controller to gain access to the testability features of system components and interfacing the controller to a diagnostics processor (or external tester) is emerging as a common strategy for designing testable digital systems. Based upon experience gained from such an application, controller features that are deemed useful are discussed.This paper is an enhanced version of the author's earlier paper titled Towards a Standard Approach for Controlling Board-Level Test Functions, presented at the IEEE International Test Conference, ITC'90, Washington D.C., September 1990.     

In-line holographic electron microscopy in the presence of external magnetic fields

It is now a well-known fact that the phase of electron waves is altered by external magnetic fields via the Aharonov-Bohm effect. This implies that any electron interference effects will be to some degree affected by the presence of such fields. In this study we examine the distortion effects of external (constant and variable) magnetic fields on electron interference and holography. For digital holography, the reconstruction of the object is done via numerical calculations and this leaves the door open for correcting phase distortions in the hologram reconstruction. We design and quantitatively assess such correction schemes, which decidedly depend on our knowledge of the magnetic field values in the holographic recording process. For constant fields of known value we are able to correct for magnetic distortions to a great extent. We find that variable fields are more destructive to the holographic process than constant fields. We define two criteria, related respectively to global and local contrast of the hologram to establish the maximum allowed external field which does not significantly hinder the accuracy of in-line holographic microscopy with electrons.     

Chemical and microbiological status and volatile profiles of mouldy Civil cheese,a Turkish mould‐ripened variety

The objective of this study is to characterise the gross chemical and microbiological status and identify the volatile compounds of mouldy Civil cheeses. A total of forty‐one samples were surveyed, and gross compositional status of the cheeses was (as mean values): 6.5 for pH, 6.2% for fat‐in‐dry matter, 51.8% for moisture and 15.3% for water‐soluble nitrogen (as% of total nitrogen). Chemical composition of the cheese samples varied widely. Mouldy Civil cheese has similar pH values and moisture contents when compared with blue‐type cheeses, but it has distinct feature for fat contents. The microbiological counts of the samples were found to be high and some samples contained coliform bacteria. A total of 95 volatiles, including esters (28), acids (6), ketones (12), aldehydes (3), alcohols (15), terpenes (10), sulphur compounds (3) and miscellaneous (18), were identified in the volatile fractions of the cheeses, and principal volatile groups were esters, alcohols and ketones.     

Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.