The world’s largest tropical peatland complex is found in the central Congo Basin. However, there is a lack of in situ measurements to understand the peatland’s distribution and the amount of carbon stored in it. So far, peat in this region has been sampled only in largely rain-fed interfluvial basins in the north of the Republic of the Congo. Here we present the first extensive field surveys of peat in the Democratic Republic of the Congo, which covers two-thirds of the estimated peatland area, including from previously undocumented river-influenced settings. We use field data from both countries to compute the first spatial models of peat thickness (mean 1.7 ± 0.9 m; maximum 5.6 m) and peat carbon density (mean 1,712 ± 634 MgC ha−1; maximum 3,970 MgC ha−1) for the central Congo Basin. We show that the peatland complex covers 167,600 km2, 36% of the world’s tropical peatland area, and that 29.0 PgC is stored below ground in peat across the region (95% confidence interval, 26.3–32.2 PgC). Our measurement-based constraints give high confidence of globally significant peat carbon stocks in the central Congo Basin, totalling approximately 28% of the world’s tropical peat carbon. Only 8% of this peat carbon lies within nationally protected areas, suggesting its vulnerability to future land-use change.

The Lee and Heghinian's bayesian approach was applied to CRU TS 3.1 grid precipitation data to detect change points at the Congo watershed scale. The locations that were sensitive to change point h...

Plants initiate the development of defense mechanisms as soon as pests start to cause damage to them. In order to have a thorough understanding of the physiological mechanisms of the Pinus massoniana self-defense mechanism, and to provide a theoretical foundation for an effective ecological management of this plant, levels of tannin, polyamine and phenolic acids were analyzed in undamaged (UDL), insect-damaged (IDL) and artificially-damaged (ADL) leaves at different times. Results show that, although the content of tannin significantly increased in IDL and ADL compared to UDL, its peaks appeared earlier in ADL than in IDL treatment. Tannin concentration substantially increased again 48 h after IDL treatment. On the other hand, the damage mode considerably affected putrescine and spermidine levels in leaves. Their concentrations in IDL plants remained higher than in UDL after a relatively long time (72 h), but spermine was barely detected in any of the samples. In general, total content of phenol acids significantly increased in damaged leaf treatments (ADL and IDL), with a higher level in IDL for most of the investigated phenolic acids, except for ferulic acid. Our study showed that, when damaged by insects, Pinus massoniana rapidly produces substances required in resistance induction to insects in order to insure its self-protection.

The purpose of this study was to survey image quality and the entrance surface air kerma for patients in radiographic examinations and to perform comparisons with diagnostic reference levels. In this multinational prospective study, image quality and patient radiation doses were surveyed in 12 countries in Africa, Asia, and Eastern Europe, covering 45 hospitals. The rate of unsatisfactory images and image quality grade were noted, and causes for poor image quality were investigated. The entrance surface doses for adult patients were determined in terms of the entrance surface air kerma on the basis of X-ray tube output measurements and X-ray exposure parameters. Comparison of dose levels with diagnostic reference levels was performed. The fraction of images rated as poor was as high as 53%. The image quality improved up to 16 percentage points in Africa, 13 in Asia, and 22 in Eastern Europe after implementation of a quality control (QC) program. Patient doses varied by a factor of up to 88, although the majority of doses were below diagnostic reference levels. The mean entrance surface air kerma values in mGy were 0.33 (chest, posteroanterior), 4.07 (lumbar spine, anteroposterior), 8.53 (lumbar spine, lateral), 3.64 (abdomen, anteroposterior), 3.68 (pelvis, anteroposterior), and 2.41 (skull, anteroposterior). Patient doses were found to be similar to doses in developed countries and patient dose reductions ranging from 1.4% to 85% were achieved. Poor image quality constitutes a major source of unnecessary radiation to patients in developing countries. Comparison with other surveys indicates that patient dose levels in these countries are not higher than those in developed countries.

The ethanol extracts of fresh apical stems of Phyllanthus niruri L. (Euphorbiaceae) cultured on Murashige and Skoog (MS) medium supplemented with IBA/BAP/Coco nucifera L. milk for 1, 2, 4, and 6 months were phytochemically and biologically investigated and compared to the intact plant part and whole plant extracts. A phytochemical screening revealed the presence of steroids, terpenes, and flavonoids as the major phytochemical groups, but not the same constituents belonging to these groups in all extracts. Alkaloids were detected in whole plant extract and were in traces in the intact apical stem extract and callus extracts. Results from the in vitro antiplasmodial testing indicated that the callus extract 1 month old (IC50 = 16.3±2.5 µg/ml) exhibited activity similar to the intact plant part extract (IC50 = 18.2±2.5 µg/ml) (p = 0.05). This activity was significantly higher (p < 0.001) than that exhibited by extracts from callus cultures 2, 4, and 6 months old (25 < IC50 < 40 µg/ml). The activity of these extracts is lower than that displayed by the same extract from the whole plant (IC50 = 2.5±0.2 µg/ml).

In Zaire the distribution of four of the wild species in the genusPsophocarpus ranges from humid, evergreen, Guinea-Congolian rainforests to high altitude woodlands, dry semi-deciduous forests, and savanna. Material ofPsophocarpus scandens, P. grandiflorus, P. lancifolius, P. lecomtei, andP. lancifolius (yellow-seeded form) were collected from wild and naturalized populations in Zaire. Various organs ofP. scandens, P. grandiflorus, andP. lancifolius are used as food sources, medicinals, and as sources of tannins.Psophocarpus lancifolius andP. lecomtei have reportedly been used as a food source and fish poison, respectively. The various organs were analyzed for carbohydrate, lipid, N, S, P, K, Mg, Ca, Na, Fe, Al, Mn, B, Cu, and Zn. In their own right, these species have potential for wider use as food sources and genetic material for improvement breeding with the cultivated winged bean, Local names, phenological notes, presence of pests and diseases, and ecogeographical information are presented.

The study by Mossbauer spectroscopy of various iron (III) salts of p-substituted benzoic acids shows a dependence between Mossbauer parameters and both Hammett's σ and σ0 functions. These results suggest that the substitution of the phenyl ring does not change the ionisation state of iron. Furthermore, σ and σ0 can be readily estimated by Mossbauer spectroscopy.