Surface acoustic wave enabled pipette on a chip

Mono-disperse droplet formation in microfluidic devices allows the rapid production of thousands of identical droplets and has enabled a wide range of chemical and biological studies through repeat tests performed at pico-to-nanoliter volume samples. However, it is exactly this efficiency of production which has hindered the ability to carefully control the location and quantity of the distribution of various samples on a chip – the key requirement for replicating micro well plate based high throughput screening in vastly reduced volumetric scales. To address this need, here, we present a programmable microfluidic chip capable of pipetting samples from mobile droplets with high accuracy using a non-contact approach. Pipette on a chip (PoaCH) system selectively ejects (pipettes) part of a droplet into a customizable reaction chamber using surface acoustic waves (SAWs). Droplet pipetting is shown to range from as low as 150 pL up to 850 pL with precision down to tens of picoliters. PoaCH offers ease of integration with existing lab on a chip systems as well as a robust and contamination-free droplet manipulation technique in closed microchannels enabling potential implementation in screening and other studies

Improved Photocatalytic and Bacterial Growth Inhibition Properties Realized for PbS/SnO2-rGO Nanocomposite

PbS/SnO2 (PS) and rGO-PbS/SnO2 (rPS) nanocomposites (NCs) were synthesized through one-pot green synthesis and chemical precipitation methods. In this paper, a comparison of the synthesized composites' photodegradation and bacterial growth inhibition properties has been conducted. For both composites, XRD analyses show the presence of tetragonal-structured SnO2 and cubic-structured PbS peaks. rGO blending increases PS crystallite size from 29 nm to 34 nm. rPS NC shows uniformly packed grains with well-defined boundaries. Absorption peaks of PS redshifts with rGO inclusion. The decreased band gap for rPS might be due to the synergistic effect of sulfur/oxygen vacancies and significant interaction between rGO and PbS/SnO2 NC. The rPS catalyst demonstrated a maximum degradation efficiency of 93% against rhodamine B (RhB) dye. Antibacterial activity of PbS/SnO2 improves with rGO inclusion. PS and rPS NCs are more resistant to gram-positive bacteria than gram-negative bacteria

A review on treatment processes of chicken manure

The poultry industry is a fast-growing industry fuelled by overwhelming customer demand. Of the different poultry meat options, chicken is arguably the most popular as it is the second most staple food item in Malaysia after rice. Consequently, due to the overwhelming demand for chicken meat, chicken manure is produced in abundance. In fact, a chicken produces 80 g to 100 g of manure daily, corresponding to 3-4% of its body weight. Utilizing the raw manure as an organic fertilizer without any prior treatment results in adverse environmental consequences as this common practice acts as a vector for propagation of pathogens, attracting flies and pests as well as contributing to odour problems. Treatment methods using pesticides, effective microorganisms and daily collection and disposal have been adopted by the farmers but these techniques are relatively costly and associated with potential environmental threats. Other techniques such as composting, pyrolysis, gasification, anaerobic digestion, hydrothermal liquefaction and torrefaction are drawing interest due to their ability to convert waste to value-added products. Approximately, 77,209 tonnes of chicken manure produced per day in Malaysia in 2014 can potentially generate up to 3.86 million m3 of methane from anaerobic digestion, equivalent to potential generation of 139.5 TJ of heat or 38.7 GWh of electricity theoretically. This paper reviews the technical and practical aspects of the techniques mentioned above in terms of operation, performance and limitations. This paper also examines the preferential treatment techniques in relation to the product outputs with good market potential while being environmentally sustainable

Effect of erythrocyte aggregation and flow rate on cell-free layer formation in arterioles

Formation of a cell-free layer is an important dynamic feature of microcirculatory blood flow, which can be influenced by rheological parameters, such as red blood cell aggregation and flow rate. In this study, we investigate the effect of these two rheological parameters on cell-free layer characteristics in the arterioles (20–60 μm inner diameter). For the first time, we provide here the detailed temporal information of the arteriolar cell-free layer in various rheological conditions to better describe the characteristics of the layer variation. The rat cremaster muscle was used to visualize arteriolar flows, and the extent of aggregation was raised by dextran 500 infusion to levels seen in normal human blood. Our results show that cell-free layer formation in the arterioles is enhanced by a combination of flow reduction and red blood cell aggregation. A positive relation (P < 0.005) was found between mean cell-free layer widths and their corresponding SDs for all conditions. An analysis of the frequency and magnitudes of cell-free layer variation from their mean value revealed that the layer deviated with significantly larger magnitudes into the red blood cell core after flow reduction and dextran infusion (P < 0.05). In accordance, the disparity of cell-free layer width distribution found in opposite radial directions from its mean became greater with aggregation in reduced flow conditions. This study shows that the cell-free layer width in arterioles is dependent on both flow rate and red blood cell aggregability, and that the temporal variations in width are asymmetric with a greater excursion into the red blood cell core than toward the vessel wall