The effect of 5-aminoisophthalic acid, 3, 5-acetamidoisophthalic acid, 4, a polymer-bound 5-amidoisophthalic acid, 5, and a cross-linked analogue of the latter, 5*, on crystallisations of L-glutamic acid from water were examined. The metastable a-polymorph was crystallised in the presence of additive at minimum loadings of 10, 5 and 1% w/w for 3, 4 and 5, respectively. The cross-linked polymer 5* was less effective compared to the parent polymer 5.
Paracetamol, sulfathiazole and L-glutamic acid are presented as examples of pharmaceutical crystal polymorphic systems. The effect of N-acylated sulfathiazole derivatives (3-6) on sulfathiazole crystallisation is discussed, and possible modes of action presented. Methods for the control of the crystal polymorphism of L-glutamic acid which utilise the principles of conformation mimicry and co-operative binding are presented. The preparation of a series of bis-amides of EDTA derived from sulfathiazole, 5-aminoisophthalic acid and 4-hydroxyaniline (i.e. compounds 9a -c) is presented, as is data on the effect of these compounds on the crystallisation of, respectively, sulfathiazole, L-glutamic acid and paracetamol.
The bis[4‐(hydroxyamino)phenylsulfonyl]piperazine 5, diketopiperazine 10 and benzene 14 were synthesised as mimics of an R22(8) motif, which occurs in one crystal polymorph of sulfathiazole and in several polymorphs of sulfapyridine. When present in crystallisations of sulfathiazole and sulfapyridine, these mimics were found to have little or no effect under crystallisation conditions that favour the formation of polymorphs not containing R22(8) motifs. However, the mimics were found to completely or partially inhibit the formation of form I sulfathiazole, which contains the R22(8) dimer, in crystallisations of sulfathiazole from 1‐propanol. In crystallisations of sulfapyridine, the mimics were found to promote the formation of form III, which does not contain the R22(8) motif. These compounds therefore appear to act as “tailor‐made” additives, displaying polymorph‐selective crystal nucleation inhibition based on interaction with hydrogen‐bond network motifs.
2-Acetamidobenzamide 1 exists in two crystal polymorphic forms: α and β. The α form features an approximately planar molecular conformation and an intramolecular N−H...O hydrogen bond. In the β form, the amido groups are out of the plane of the benzene ring and no intramolecular hydrogen bonds are present. In our study, the α form was found to be the more readily obtainable initially, usually as well-formed needles. 2-Acetamido-4-chlorobenzamide 8 and 2-acetamido-5-chlorobenzamide 9 were prepared and assessed as additives in recrystallizations of 2-acetamidobenzamide. In the presence of compound 8, attempted recrystallization of 2-acetamidobenzamide gave crystals of the anhydrous form of 2-methylquinazol-4-one 4. Addition of compound 9 had no effect on the crystal form obtained. 10,11-Dihydro-5-acetyldibenzo [b,e][1,4]diazepin-11-one 14 was prepared as a conformational mimic of the molecular conformation of the β form of 2-acetamidobenzamide. Compound 14 had no effect on the recrystallization of 2-acetamidobenzamide from acetone when added in 10% w/w or from water when added in 1% w/w. When 14 was added in 10% w/w quantities to crystallizations of 2-acetamidobenzamide from water, fine crystallites were obtained which gave infra-red spectra consistent with the α form, but gave PXRD patterns suggesting the presence of another form or compound. Disruption of the intramolecular hydrogen bonds in the α form of 2-acetamidobenzamide 1 by direct trimethylsilylation gave mixtures of 1 and 2-methylquinazol-4-one 4. Indirect trimethylsilylation by reaction of 2-methyl-4H-benzo [d] [1,3]oxazin-4-one 3 with tris(trimethylsilyl)amine gave crystals of the anhydrous form of 2-methylquinazol-4-one 4. 2-Phthalimidobenzoic acid 18 and 2-phthalimidobenzamide 19 were prepared as structural analogues of compound 1 which are incapable of possessing an intramolecular hydrogen bond. Addition of compound 18 to recrystallizations of 2-acetamidobenzamide 1 had no effect on the outcome. However addition of compound 19 resulted in needle-like crystals of the α form of considerably reduced dimensions.
Introduction Evidence has shown that throughout their undergraduate years, many nursing and midwifery students obtain paid employment in a wide variety of clinical and non-clinical positions. Across Australia, inconsistencies exist in the models of clinical employment available to these student groups. Previous Australian studies have described the employment of undergraduate nursing and midwifery students in regulated and unregulated clinical roles. No studies have reported on the various regulated roles available to both student nurses and midwives in Australia. The purpose of this scoping review is to identify and synthesize evidence related to nursing and/or midwifery students employed in regulated and unregulated clinical roles in Australia. Methods This scoping review utilized published recommendations for data screening, abstraction, and synthesis. One of the authors, a librarian, undertook systematic searches in CINAHL Complete (1937–present), Emcare on Ovid (1995–present), Scopus (1969–present), and Ovid MEDLINE(R) (including Epub Ahead of Print, In-Process, and In-Data-Review & Other Non-Indexed Citations, 1946–present). The initial searches were completed in April 2019 and repeated in March 2021 and May 2022 to identify any new literature. Manual searching of reference lists in the included papers was also undertaken, together with selected organizational websites. The extracted data included the lead author, date, title, study design, study sample and location, and key findings. Results From the 53 items retrieved, 23 peer-reviewed studies met the inclusion criteria and were included in the review. All items were published between 2011 and 2022. Only four of the studies focused upon student midwives. Undergraduate nursing and midwifery students in Australia obtain paid employment in a variety of regulated and unregulated clinical roles. Conclusion The literature reported here demonstrates that there are differing models, nomenclature, educational requirements, and pay scales in place for student employment in clinical roles across Australian states and territories.
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