The paper provides an empirical analysis of the macroeconomic factors that enhance revenue gap in South Africa using the multivariate cointegration techniques for the period 1965 to 2012. The results from the cointegration analysis indicate that the revenue gap in South Africa is negatively associated with the level of imports while positively related to external debt and underground economy. The former finding is consistent with the notion that imports are subjected to more taxation than domestic activities because of certain features of international trade that tend to make tax evasion difficult. On the other hand, the positive relationship between external debt and tax gap shows that the South African government relies upon external debt to finance its budget deficit resulting from missing revenues. Furthermore, the observed negative effect of the post-apartheid dummy confirms that the tax policy reforms that South Africa introduced following the liberation in 1994 have led to a reduction in missing revenues. The results from the Granger causality test also show that there is a unidirectional causality running from imports and underground economy to revenue gap, while revenue gap on the other hand is found to Granger-cause national income and external debt in South Africa.

Recent studies of pyroelectricity in crystallized aromatic compounds – benzene derivatives – are discussed and summarized. The dielectric and pyroelectric behaviour of some di‐ and trisubstituted benzenes as a function of temperature is presented and experimental results are compared with evaluations based on the INDO‐approximation including a self‐consistant electrostatic crystal field approach.

By 79,81 Brand "' I NQR the hydrobromides of glycine, I-alanine, I-leucine, 1-proline, semicarbazide and the hydroiodides of I-leucine and semicarbazide were studied in the temperature range 77 5 T/K < decomposition point. Furthermore the compound diglycine sodium iodide monohydrate was investigated. A phase transition is observed for I-leucine hydrobromide at 331.5 K, which is reversible and of small transition enthalpy, as shown by DTA. -79*8i Br NQR frequencies are strongly influenced by hydrogen bonds N+ -H . . . Br-and 0 -H . . . Br-. The "Br frequencies can be grouped into two bands, one at 15 < v/MHz < 19, the other at 24 < v/MHz < 26. The high frequency group of compounds is characterized by N + -H . . . Br-and 0-H . . . Br-hydrogen bonds, whereas the bond scheme of the low frequency compounds is determined by bonds N+ -H . . . Br-only. This grouping of the amino acid hydrobromides according to frequency band and hydrogen bond scheme can be applied to the hydroiodides and to diglycine sodium iodide monohydrate, too.

By 79,81Br and 127I NQR the hydrobromides of 1‐asparagine, 1‐asparatic acid, glycyl‐1‐alanine, and glycylglycine and the hydriodides of 1‐asparagine, 1‐glutamic acid, and glycylglycine were studied in the temperature range of 77 ≤ T/K ≤ 420 (or decomposition point). — A reversible phase transition is observed for glycyl‐1‐alanine hydrobromide at 203 ± 1 K. 79,81Br NQR frequencies are strongly influenced by N⊕—H…Br⊖ and O—H…Br⊖ hydrogen bonds. The 79Br frequencies can be grouped into two bands, one at 12.4 < v/MHz < 18.5, the other at 24.8 < v/MHz < 26.4. The compounds of the high frequency group are characterized by N⊕—H…Br⊖ and O—H…Br⊖ hydrogen bonds, whereas the bond scheme of the low frequency compounds is determined by N⊕—H…Br⊖ bonds only. This grouping of amino acid and dipeptide hydrobromides according to frequency band and hydrogen bond scheme can be applied to the hydriodides, too. The ones with a O—H…I⊖ hydrogen bond have nuclear quadrupole coupling constants of N⊕ > 120 MHz, the other compounds with N⊕—H…I⊖ hydrogen bonds only show nuclear quadrupole coupling constants of 70 < e2QzzQh−1/MHz < 120.

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