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This study aims to highlight the relationships between the structure of smell compounds and their odors. For this purpose, heterogeneous data sources were screened, and 6038 odorant compounds and their known associated odors (162 odor notes) were compiled, each individual molecule being represented with a set of 1024 structural fingerprint. Several dimensional reduction techniques (PCA, MDS, t-SNE and UMAP) with two clustering methods (k-means and agglomerative hierarchical clustering AHC) were assessed based on the calculated fingerprints. The combination of UMAP with k-means and AHC methods allowed to obtain a good representativeness of odors by clusters, as well as the best visualization of the proximity of odorants on the basis of their molecular structures. The presence or absence of molecular substructures has been calculated on odorant in order to link chemical groups to odors. The results of this analysis bring out some associations for both the odor notes and the chemical structures of the molecules such as “woody” and “spicy” notes with allylic and bicyclic structures, “balsamic” notes with unsaturated rings, both “sulfurous” and “citrus” with aldehydes, alcohols, carboxylic acids, amines and sulfur compounds, and “oily”, “fatty” and “fruity” characterized by esters and with long carbon chains. Overall, the use of UMAP associated to clustering is a promising method to suggest hypotheses on the odorant structure-odor relationships.

This paper summarizes the results of our experiments studying the effect of functional chemical groups of synthetic hydrophilic polymers on the recognition of these materials by macrophages in in vivo experiments. The interaction of keratinocytes with synthetic hydrophilic polymers in vitro is also demonstrated. The implants containing anionic groups (carboxylates) were shown to be better tolerated by nonspecific immunity. The keratinocytes are able to grow on hydrophilic polymer supports and migrate to surfaces with improved adhesivity (in vitro). The clinical applications of these experiments are demonstrated.

Hammett1 points out that the —SH group is the essential chemical stimulus for cell division. He also concludes2 that the greater the natural cell division activity the greater the degree of reaction to the chemical groups. Coldwater3 regards the nitroprusside reaction as indicating the presence of protein-fixed —SH groups, and finds a high concentration of this sulphydryl in areas of regenerating tissues undergoing proliferative growth. Thompson and Voegtlin,4 Murray,5 and Yaoi6 have found the glutathione content of embryos of the chick and rat to be at a maximum in early development and to decrease with age.One might infer from the above that if embryos were tested for the —SH groups at periods of marked cellular activity a much stronger reaction would be obtained than if they were tested at periods of relative inactivity. The embryo of the grasshopper, Melanoplus differentialis, is favorable material for this test as it can be obtained in large numbers, is easily dissected out, and is so small that it i...

Several correlation charts are available in the literature for the assignments of infrared bands to chemical groups. Because of the difficulty of condensing the required information on to a small area, these tend to be inconveniently large or somewhat congested and difficult to read.

KNOWLEDGE of the preferred conformation of chemical groups has been shown to be essential for the determination of the structures of biological molecules. The prime example is the elucidation of the structure of the α-helix for protein molecules by Pauling, Corey and Branson1 from knowledge that the peptide group is coplanar and the importance of the hydrogen bond, whereas others had proposed incorrect structures owing to lack of this knowledge. On a more complicated scale, because the energy stabilizing the preferred conformation is less, but on an important biological scale, it was pointed out by Canepa, Pauling and Sorum2 that the N+–C–C–O– group is synclinal. This was shown more clearly by Sundaralingam3 and recently shown to be true in solution by Partington, Feeney and Burgen4. The conformation of this group is of great importance in nervous transmitter substances5 and in phospholipids.

ATTENTION was first directed to the principles involved in explaining the differential reaction of two ‘identical’ groups in a single molecule by Ogston1, and they have been further discussed and generalized by Wilcox2, Schwartz and Carter3 and most recently by Hirschmann4. Since a recent review5 seems to hold that the views of these authors (in particular those of Ogston and of Schwartz and Carter) are in some ways contradictory, and since Hirschmann's excellent article appears to be too little known, a brief re-statement is attempted. Ogston's and Schwartz and Carter's views are in fact complementary (as Hirschmann shows), each being explicit about an aspect of the matter which the other takes for granted.

THE synthesis of new cytostatic drugs is governed by the attempt to find new substances which unite maximum therapeutic effectiveness with minimum toxicity. For this purpose it seems to be advantageous not to apply the substance in its active form, but by introducing suitable chemical groups to transform it into an inert transport substance which will be reconverted into the active form at the site of therapeutic action in the body. This principle has already proved of value in the treatment of prostatic carcinoma with stilbœstrol diphosphate1.

Although cases of skin hypersensitiveness to procaine hydrochloride have been reported, in only a comparatively small number has the blame been absolutely fixed on this substance by means of skin tests, as, for instance, in the cases reported by C. Guy Lane. 1 Lane found that, in two patients suffering from a dermatitis of an erythematous papulovesicular type, the chance spilling of procaine on the skin while performing the scratch skin test caused an eczematous skin reaction to appear the following day. The skin eruption was limited to the area on which the procaine had been spilt. In Lane's cases the scratch test for immediate wheal formation was negative. This is in accordance with what has been recently noted as being the case in dermatitis of the eczematous type. The scratch test is usually negative but the contact test is positive. In the case of Galewsky, 2 dermatitis due to

Analytical Chemistry of Polymers Edited by Gordon M. Kline. Part 2: Analysis of Molecular Structure and Chemical Groups. Pp. xiii + 619. Part 3: Identification Procedures and Chemical Analysis. Pp. xii + 566. (High Polymers: a Series of Monographs on the Chemistry, Physics, and Technology of High Polymeric Substances, Vol. 12, Parts 2 and 3.) (New York and London: Interscience Publishers, a Division of John Wiley and Sons, Inc., 1962.) Part 2 132s.; Part 3 124s.

Since Baumann, 1 in 1896, discovered that iodin is a normal constituent of the thyroid gland, it has been obvious that the isolation in pure crystalline form of the compound containing iodin was necessary before we could know the function of the gland and the relation of iodin to this function. There are many mechanical difficulties involved in the isolation of the iodin compound. It occurs at best in one part in 4,000, and during many months of the year the amount present is not more than one part in 10,000 of fresh glands. For the completion of this work, eight years of practically continuous investigation and more than 2 tons of thyroid glands have been used. Some 20 gm. of the active constituent in pure crystalline form have been separated. The investigation, besides involving the separation of this substance, has also included the determination of its chemical formula both

Certain blue glass beads from west African archaeological sites have been found by X-ray fluorescence analysis to fall into two chemical groups. Each group includes beads which exhibit blue/yellow dichroism' and/or cords.z Held in the hand, the dichroic examples appear blue, but against the light they appear greenish-yellow. One group of dichroic and corded beads appears to belong to the glass industry of Ife, and that relationship will be discussed in a forthcoming report. The present article presents the two chemical groups and discusses possible relationships between them. The blue dichroic beads are the subject of a tangled literature dating back at least to I603 (Zecchin I955; I964). It has not been previously recognised that the corded beads belong with the dichroic; in fact, forms intermediate between the two are found. Dichroic beads are considered by modern scholars to fall within the 'akori bead' problem, the main point of which is to define the word 'akori'. Some two dozen accounts spaced over about four hundred years allude to, or partially describe 'akori' beads (spelled variously 'accarey', 'aggrey', 'cori', etc.). Taken together the accounts are contradictory and ambiguous with respect to the name, colour, material, and source of akori. Reconciliation of these accounts by recent authors has yielded some consensus (Fage i962;Jeffreys I96I; Kalous I966; I968; Mauny I958; I96I); however, this has the drawback that historical accounts which may have applied to different things have been blended to form a rather syncretic picture, which consequently may contain anachronisms and other difficulties. The consensus view postulates the existence of both 'true' and 'imitation' akori. The 'true akori' are claimed to be made of an unknown material, while the imitations are of glass. 'True akori' were collected in the area (generally from either the ground, old graves, beside water, or the hinterland) from Dahomey to the Cameroons (Braun I624; de Marees I602; du Casse c. I688; Ruiters I623; Romer 1769; Ryder 1959); and in the sixteenth century, in Manicongo as well (Anon. c. 1540). They were purchased by Europeans and taken to the Gold Coast (Ghana) where they were sold (Anon. c. I540; Braun I624; de Marees I602; du Casse c. i688; Pereira c. I508; Ruiters I623; Ryder I959). By the nineteenth century, they were found in the hinterland of the Gold Coast as well (Bowdich I8I9). There are many other beads found in west Africa that are not claimed to be akori. Although most frequently blue, akori beads occur in many different colours. True akori were said to be worth their weight in gold. They apparently softened

The empirical CHARMM additive all-atom force field has been widely used for proteins, nucleic acids, lipids and carbohydrates, with the CHARMM General Force Field (CGenFF) portion of the force field specifically developed for chemical groups present in drug-like molecules. To more accurately treat linked nitrogen-containing heteroaromatic rings CGenFF was extended to molecules such as bi-pyridine, bi-pyrimidine, and bi-pyrrole. Target data include QM data for geometries, vibrations and dihedral potential energy scans (PES) as well as interactions with water. A total of 12 additional compounds were parameterized. To achieve adequate optimization it was necessary to introduce new atom types for selected linker atoms. A detailed comparison of the QM and MM data for the optimized parameters will be presented along with application of the model in MD simulations.