Polymers from intermediates obtained from hydrogen cyanide

The recent demonstration of an easy synthesis of diiminosuccinonitrile (DISN) from hydrogen cyanide and cyanogen, the reduction of DISN to diaminomaleonitrile (DAMN), and the use of these compounds to form difunctional heterocycles has made several new polyamide intermediates accessible. The 1- and 2-methyl-1,2,3-triazole-4,5-dicarbonyl chlorides have been polymerized interfacially to form high-melting polyamides of good heat stability. Interfacial polymerization of 1-methylimidazole-4,5-dicarbonyl chloride and trans-2,5-dimethylpiperazine has given a polyamide that is water-soluble. The 2,6- and 2,3-pyrazinedicarbonyl chlorides have been similarly converted to high-melting polyamides. 2,6-Dicyano-3,5-dipiperazinylpyrazine has been prepared from tetracyanopyrazine and piperazine and reacted with toluene diisocyanate to form a strong, stiff polyurea. Polyamides were also made from 2,3-diaminoquinoxaline, 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, and DAMN.     

Fish attractants from marine invertebrates: Arcamine from Arca Zebra and strombine from Strombus Gigas

The isolation and characterisation of two fish attractants, a new dipeptide (Arcamine, hypotauryl-2-carboxyglycine),1 and Strombine (C-methyl-imino diacetic acid),2 are described.     

Stereocomplex Formation from Enantiomeric Polyamides Derived from Tartaric Acid

Summary: The formation of stereocomplexes from the pair of enantiomorphs of the chiral polyamide poly(hexamethylene di‐O‐methyl tartaramide) was investigated for a variety of experimental conditions. DSC and X‐ray diffraction data evidenced that efficiency in enantiomeric association is highly sensitive to the procedure used for preparing the complex. A comparative isothermal crystallization study revealed that the stereocomplex crystallized from the melt at a rate lower than the enantiomerically pure components. The radial growth of individual spherulites was also delayed in the crystallization of the complex. No evidence of stereocoupling was detected for other poly(alkylene di‐O‐methyl tartaramide)s with the alkylene unit length different from six. It was concluded that molecular interlocking of hydrogen bonds in the enantiomeric pair is highly selective in this family of polymers.

Spherulitic growth at 200 °C from the melt.     

Cytotoxic diterpenoids from Podocarpus madagascariensis from the Madagascar rainforest

Bioassay-directed fractionation of an extract of the root and bark of Podocarpus madagascariensis resulted in the isolation of a new totarol diterpenoid (1) in addition to the three known cytotoxic diterpenoids 19-hydroxytotarol (2), totaradiol (3), and 4beta-carboxy-19-nor-totarol (4). The structure of the new compound 1 was established as methyl-13-hydroxy-14-isopropyl-9(11),12,14(8)-podocarpatriene-19-oate on the basis of 1D and 2D NMR spectroscopic interpretation and methylation of 4. All the compounds exhibited cytotoxic activity against the A2780 ovarian cancer cell line.     

Synthesis of isoxazolines from nitrile N-oxides generated from nitroalkenes

In this review, information on the production of isoxazolines and condensed isoxazoline systems by the intramolecular 1,3-bipolar cycloaddition of unsaturated nitrile N-oxides generated in situ from nonconjugated nitroalkenes is generalized and systematized. The isoxazoline derivatives formed as the result of these reactions are promising synthons in the synthesis of various natural compounds and their analogues.Krakow Polytechnic Institute, Poland. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 291–305, May–August, 1992.     

Engineers are from PDMS-land, Biologists are from Polystyrenia

As the integration of microfluidics into cell biology research proceeds at an ever-increasing pace, a critical question for those working at the interface of both disciplines is which device material to use for a given application. While PDMS and soft lithography methods offer the engineer rapid prototyping capabilities, PDMS as a material has characteristics that have known adverse effects on cell-based experiments. In contrast, while polystyrene (PS), the most commonly used thermoplastic for laboratory cultureware, has provided decades of grounded and validated research conclusions in cell behavior and function, PS as a material has posed significant challenges in microfabrication. These competing issues have forced microfluidics engineers and biologists to make compromises in how they approach specific research questions, and furthermore, have attenuated the impact of microfluidics on biological research. In this review, we provide a comparison of the attributes of PDMS and PS, and discuss reasons for their popularity in their respective fields. We provide a critical evaluation of the strengths and limitations of PDMS and PS in relation to the advancement and future impact on microfluidic cell-based studies and applications. We believe that engineers have a responsibility to overcome any challenges associated with microfabrication, whether with PS or other materials, and that engineers should provide options and solutions that assist biologists in their experimental design. Our goal is not to advocate for any specific material, but provide guidelines for researchers who desire to choose the most suitable material for their application, and suggest important research directions for engineers working at the interface between microfabrication technology and biological application.     

Alkaloids from the Tunicate Polycarpa aurata from Chuuk Atoll

Two new alkaloids, polycarpine (1) and N,N-didesmethylgrossularine-1 (4), have been isolated from extracts of the ascidian Polycarpa aurata collected in Chuuk, Federated States of Micronesia. Three degradation products of 1 were also isolated. The structures of 1, 2, and 4 were determined by X-ray crystallography. The dimeric disulfide 1 inhibited the enzyme inosine monophosphate dehydrogenase, but the inhibition could be reversed by addition of excess dithiothreitol suggesting that 1 reacts with sulfhydryl groups on the enzyme.     

Small angle X-ray scattering from amorphous polymers arising from heterogeneities

Summary The small angle X-ray scattering of glassy polymers (PET, PC, PVC, PMMA) and of polymer melts (PE) was studied. The dependence of the intensity scattered at small angles on the sample treatment suggests that neither the inherent structure of the pure polymer phase nor microholes are the origin of the scattering. In agreement with all experimental facts the scattering can be attributed to foreign particles such as for instance stabilizers in the polymer matrix. The consequence of this result is discussed with respect to the nodular structure of the amorphous phase and with respect to structural models of the amorphous phase. The nodular structure is not related to regions of different densities within the pure amorphous phase.The small angle X-ray scattering can be used to characterize the microscopic and macroscopic distribution of additives in polymer samples.

---

Zusammenfassung Es wurden Röntgenkleinwinkeluntersuchungen an glasig erstarrten Polymeren (PÄT, PC, PVC, PMMA) und an Polymerschmelzen vorgenommen (PÄ). Die Abhängigkeit der bei kleinen Winkeln beobachteten Streuung von der Probenbehandlung weist darauf hin, daß weder die innere Struktur der amorphen Phase noch Mikrolöcher die Ursache für die Streuung sein können. In Übereinstimmung mit allen Ergebnissen wird die Streuung Fremdpartikeln wie z. B. Stabilisatoren in der Polymermatrix zugeschrieben. Die Folgerungen, die sich hieraus ergeben, werden hinsichtlich der Körnerstruktur der amorphen Phase und der Strukturmodelle diskutiert. Die Körnerstruktur kann nicht durch Bereiche unterschiedlicher Dichte in der amorphen Phase erklärt werden.Die Röntgenkleinwinkelstreuung kann zur Charakterisierung der makroskopischen und der mikroskopischen Verteilung der Zusätze im Polymeren herangezogen werden.

     

New azaphilones from Chaetomium globosum isolated from the built environment

A strain of Chaetomium globosum (DAOM 240359) was isolated from an indoor air sample in Ottawa, Ontario, Canada. When fermented in liquid culture, this strain produced a number of known metabolites including chaetoglobosins A (6), C, and F (7), chaetomugilin D (5), chaetoviridin A (4), and three new nitrogenous azaphilones; 4′-epi-N-2-hydroxyethyl-azachaetoviridin A (1), N-2-butyric-azochaetoviridin E (2), and isochromophilone XIII (3). The structures were elucidated by spectroscopic analysis including; HRMS, 1D and 2D NMR, UV, and ORD. Compounds 2–7 were antimicrobial when tested using quantitative growth inhibition assays.     

Acetylenic thiophenes from the roots of Escinops ellenbeckii from Ethiopia

The hexane fraction from the roots of Echinops ellenbeckii O. Hoffm. from Ethiopia yielded seven acetylenic thiophenes of which five compounds (1, 3, 4, 6, 7) are reported for the first time in this species: the monothiophenes 5-(penta-1,3-diynyl)-2-(but-3-en-1-ynyl)-thiophene (1), 5-(penta-1,3-diynyl)-2-(4-acetoxy-but-1-ynyl)-thiophene (2), 5-(penta-1,3-diynyl)-2-(3-hydroxy-4-acetoxy-but-1-ynyl)-thiophene (3), 5-(penta-1,3-diynyl)-2-(3,4-diacetoxy-but-1-ynyl)-thiophene (4), 5-(penta-1,3-diynyl)-2-(3-chloro-4-acetoxy-but-1-ynyl)-thiophene (5), 5-(penta-1,3-diynyl)-2-(3,4-epoxy-but-1-ynyl)-thiophene (6) and the dithiophene 5-[(5-acetoxymethyl-2-thienyl)-2-(but-3-en-1-ynyl)]-thiophene (7). Additionally, four fatty acids (C14, C15, C16 and C18), seven fatty acid esters and three long-chain hydrocarbons could be identified. All the structures were elucidated on the basis of spectral data by GC-MS, HRMS and the NMR techniques.     

Precipitation from homogeneous solution of cations released from ETDA complexes

The suitability of EDTA complexes for use in precipitation of certain cations from homogeneous solution under various experimental conditions can be predicted from a knowledge of the solubility product of the compound to be precipitated and the complex stability constant. A brief review of previous work in the field of masking effectiveness is given. An examination of factors influencing precipitation has been carried out. It is shown that a simple ratio can be used for predicting the likelihood of precipitation at various pH values and that more rigorous theoretical approaches are not necessarily more advantageous.     

Structurally diverse diterpenoids from Isodon ternifolius collected from three regions

Phytochemical investigation of the aerial parts of Isodon ternifolius from three regions in Yunnan Province afforded 9 new diterpenoids, ternifoliusins A–I (1–9), together with 26 known diterpenoids. Among them, ternifoliusins A–D possess rare 6,7:8,15-diseco-7,20-olide-6,8-cyclo-ent-kaurane diterpenoid scaffold. The structures of all compounds were determined by comprehensive spectroscopic analysis, as well as quantum chemical calculation methods. Moreover, the molecular constitutions and configurations of ternifoliusins A, E, and F (1, 5, 6) were confirmed by single-crystal X-ray diffraction analysis. Ten compounds were assayed for their cytotoxic activity against the HL-60, SMMC-7721, A-549, MCF-7, and SW-480 human tumor cell lines, and compounds 13, 17, 19, 20, 31 and 34 were demonstrated to be active against all of the five human tumor cell lines.     

Radiation from metastable highly-charged ions extracted from a gas target

Few-electron ions of argon have been produced by heavy ion impact in a gas target. The recoil ions have been extracted into a region with high vacuum, and the K radiation of long-lived states has been observed by means of a position sensitive proportional counter oriented along the flight path of the ions. Fast ion beams are frequently used to determine the lifetimes τ of excited levels by time-of-flight techniques [1]. Typical ion velocities are v=1 cm/ns (beam energy 0.5 MeV/amu) or higher. The usual length l of experimental chambers rarely exceeds l=1 m. This decay path corresponds to roughly 100ns, and very few experiments on fast ion beams have been done on longer-lived states. Notable examples are the Berkeley measurements on the Ar¹⁶⁺ 1s2s³S₁ lifetime (calculated around τ=210 ns [2, 3], decay path ～8m) which resulted in a lower lifetime result (172±30ns) than expected and which were later shown to suffer from various systematic errors, the most important being the lack of spectral resolution of radiation from the helium-like or from core-excited lithiumlike ions. An alternative approach, a coincidence measurements of x-rays and projectile ions to associate the detected quanta with ions of a given charge state is difficult for high energy and high current ion beams.