Preparation, characterization, and X-ray crystal structures of helical and syndiotactic zinc-based coordination polymers.

The reactions of (facac)2Zn.2H2O (facac = 1,1,1,5,5,5-hexafluoroacetylacetonate) with 2,5-bis(4-ethynylpyridyl)furan (1) and 1,2-bis(4-ethynylpyridyl)benzene (2) yield, upon crystallization, coordination polymers. The former polymer, ((facac)2Zn.1)n, has an isotactic, helical structure in the solid state [monoclinic space group P2(1)/n; a = 11.0374(3) A, b = 24.2179(10) A, c = 14.3970(4) A, beta = 92.880(2) degrees; Z = 4]. The latter polymer, ((facac)2Zn.2)n, adopts a syndiotactic structure in the solid state [monoclinic space group P2(1)/n; a = 9.1344(1) A, b = 21.7985(5) A, c = 16.0322(4) A, beta = 99.6680(11) degrees; Z = 4]. The solution structures of the corresponding oligomers have been studied by low-temperature 1H and 19F NMR spectroscopy. Chiral polymers were prepared using the fragment [(+)-tfc]2Zn ((+)-tfc = 3-((trifluoromethyl)hydroxymethylene)-(+)-camphorate). A linear, zigzag structure was found for ([(+)-tfc]2Zn.1)n [triclinic space group P1; a = 7.4833(2) A, b = 14.1563(5) A, c = 21.21230(5) A, alpha = 78.4440(15) degrees, beta = 81.5644(15) degrees, gamma = 76.4976(13) degrees; Z = 1]. Reaction with tris(4-pyridyl)methanol (3) yielded a homochiral, helical polymer, ([(+)-tfc]2Zn.3)n [monoclinic space group C2; a = 25.0633(12) A, b = 11.8768(7) A, c = 17.1205(9) A, alpha = 90 degrees, beta = 117.954(3) degrees, gamma = 90 degrees; Z = 4].

Private-public sector co-operation to improve pesticide safety standards in developing countries.

This paper draws on the author's experiences of the pilot phase of the Safe Use Project (SUP) in Thailand; this project is a part of a major GIFAP initiative carried out in some developing countries. The SUP's objectives were; i) to raise awareness and compliance in the safe handling and storage of pesticides within the industry, the medical profession and the end-users; ii) to reduce the incidence of pesticide poisoning; iii) to protect the environment; iiii) to help relevant government agencies with resources, expertise and training. To achieve those objectives, the SUP used local-language training resources, provided basic training, lobbied for changes in governmental policies and regulations, and acted as a focal point for pesticide safety-related information. The SUP targeted the whole distribution chain, from importer/formulator, through to the endusers. Also medical profession, teachers and school students were targeted. On the base of independent audit and surveys, a general improvement in awareness has been shown within targeted groups; a longer time frame is required to detect meaningful changes in farmer practice. The SUP key programmes have been: I) training of trainers, retailers and farmers; II) schools programme; III) medical training; IV) protective clothing; V) industry standards; VI) model farm. The main conclusions of the pilot phase were: i) pesticide safety needs to be addressed by all concerned agencies in a joint effort; ii) a rural development perspective must be adopted in improving pesticide safety; iii) integrated pest management training programmes must include precautionary advice for proper handling, use and disposal of pesticides, wherever these are necessary.

Left ventricular dysfunction induced by cold exposure in patients with systemic sclerosis.

Raynaud's phenomenon and cardiac abnormalities are frequent in patients with systemic sclerosis. Radionuclide ventriculograms were obtained in 16 patients with Raynaud's phenomenon and systemic sclerosis or the related CREST syndrome and in 11 normal volunteers in order to evaluate changes in left ventricular function that might be induced by exposure to cold. Left ventricular regional wall motion abnormalities developed in nine of 16 patients during cooling compared with only one of 11 control subjects, despite a comparable rise in mean arterial pressure (p less than 0.02). The abnormalities occurred in seven of 11 patients with systemic sclerosis, one of four with CREST syndrome, and one with Raynaud's disease. To test the potential protective effect of nifedipine, radionuclide ventriculograms were then obtained during cooling after sublingual nifedipine (20 mg). Only five of 13 patients had wall motion abnormalities, and the severity of the abnormalities was significantly less than during the first cooling period (p = 0.03). Five of eight patients who had cold-induced wall motion abnormalities during the first cooling period had none after nifedipine, whereas two other patients demonstrated small abnormalities only during the second cooling period after treatment with nifedipine. It is concluded that cold induces segmental myocardial dysfunction in patients with systemic sclerosis and that nifedipine may blunt the severity of this abnormal response.