Biogas Quantity and Quality from Digestion and Co-Digestion of Food Waste and Cow Dung

The aim of this study is to assess the quantity and quality of biogas produced from single substrate digestion of food waste and cow dung as well as co-digestion of food waste and cow dung. Laboratory sized 25 litre plastic biodigesters were used in this study and the digestion processes was carried out for a 30 day retention period. The results revealed that the cumulative biogas production for the single substrate digestion of cow dung was 7,975 ml, the cumulative biogas produced for the single substrate digestion of food waste was 7,742.5 ml while the cumulative volume of biogas produced for the co-digestion of cow dung and food waste was 16,482.5 ml. The results also showed that the total volume of methane produced for the single substrate digestion of cow dung was 955 ml while the total methane produced for the single substrate digestion of the food waste was 765. The total production of methane for the co-digestion of cow dung and food waste was found to be 2,655 ml. This study revealed that though the co-digestion process improved biogas quantity and quality, the percentage methane present in the biogas very low. There would be a need to stimulate the digestion and co-digestion process in order to improve the quality of biogas produced.

A Single-Substrate Biosensor with Spin-Coated Liquid Crystal Film for Simple, Sensitive and Label-Free Protein Detection

A liquid crystal (LC)-based single-substrate biosensor was developed by spin-coating an LC thin film on a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-decorated glass slide. Compared with the conventional sandwiched cell configuration, the simplified procedure for the preparation of an LC film allows the film thickness to be precisely controlled by adjusting the spin rate, thus eliminating personal errors involved in LC cell assembly. The limit of detection (LOD) for bovine serum albumin (BSA) was lowered from 10−5 g/mL with a 4.2-μm-thick sandwiched cell of the commercial LC E7 to 10−7 g/mL with a 4.2-μm-thick spin-coated E7 film and further to 10−8 g/mL by reducing the E7 film thickness to 3.4 μm. Moreover, by exploiting the LC film of the highly birefringent nematic LC HDN in the immunodetection of the cancer biomarker CA125, an LOD comparable to that determined with a sandwiched HDN cell was achieved at 10−8 g/mL CA125 using a capture antibody concentration an order of magnitude lower than that in the LC cell. Our results suggest that employing spin-coated LC film instead of conventional sandwiched LC cell provides a more reliable, reproducible, and cost-effective single-substrate platform, allowing simple fabrication of an LC-based biosensor for sensitive and label-free protein detection and immunoassay.

Towards a Dialect History of the Baggara Belt

The Baggara Belt constitutes the southernmost periphery of the Arabic-speaking world. It stretches over 2500 km from Nigeria to Sudan and it is largely inhabited by Arab semi-nomadic cattle herders. Despite its common sociohistorical background, the ethnography of Baggara nomads is complex, being the result of a long series of longitudinal migrations and contacts with different ethnolinguistic groups. Thanks to a number of comparative works, there is broad agreement on the inclusion of Baggara dialects within West Sudanic Arabic. However, little or nothing is known of the internal classification of Baggara Arabic. This paper seeks to provide a comparative overview of Baggara Arabic and to explain dialect convergences and divergences within the Baggara Belt in light of both internally and externally motivated changes. By providing a qualitative analysis of selected phonological, morphosyntactic, and lexical features, this study demonstrates that there is no overlapping between the ethnic and dialect borders of the Baggara Belt. Furthermore, it is argued that contact phenomena affecting Baggara Arabic cannot be reduced to a single substrate language, as these are rather induced by areal diffusion and language attrition. These elements support the hypothesis of a gradual process of Baggarization rather than a sudden ethnolinguistic hybridization between Arab and Fulani agropastoralist groups. Over and above, the paper aims at contributing to the debate on the internal classification of Sudanic Arabic by refining the isoglosses commonly adopted for the identification of a West Sudanic dialect subtype.

Fates of Sec, Tat, and YidC Translocases in Mitochondria and Other Eukaryotic Compartments

Formation of mitochondria by the conversion of a bacterial endosymbiont was a key moment in the evolution of eukaryotes. It was made possible by outsourcing the endosymbiont’s genetic control to the host nucleus, while developing the import machinery for proteins synthesized on cytosolic ribosomes. The original protein export machines of the nascent organelle remained to be repurposed or were completely abandoned. This review follows the evolutionary fates of three prokaryotic inner membrane translocases Sec, Tat, and YidC. Homologs of all three translocases can still be found in current mitochondria, but with different importance for mitochondrial function. Although the mitochondrial YidC homolog, Oxa1, became an omnipresent independent insertase, the other two remained only sporadically present in mitochondria. Only a single substrate is known for the mitochondrial Tat and no function has yet been assigned for the mitochondrial Sec. Finally, this review compares these ancestral mitochondrial proteins with their paralogs operating in the plastids and the endomembrane system.