An investigation of thermal environment of an existing UFAD system in a high-rise office building in the tropics.

The current case study was conducted to identify the causes of environmental health issues in the office space associated with the existing Underfloor Air Distribution (UFAD) system in a high-rise office building in the tropics. The causes of the indoor environmental quality degradation are the key to resolve the environmental health issues. Thus, the parameters such as the indoor air temperature, relative humidity (RH), relative air velocity, carbon monoxide (CO), carbon dioxide (CO2), formaldehyde, total volatile organic compound (TVOC) and particulate matter (PM10) were evaluated in five office spaces. The results showed that the diffusers were not effective in creating air mixing at the occupied space. The RH has exceeded the threshold limit of 70%. The CO2 concentration has exceeded 1000 ppm, and the formaldehyde has exceeded 0.1 ppm. These indicate the poor design and maintenance of the building that lead to the degradation of indoor environmental quality. Long exposure to the poor indoor environmental quality will cause permanent health damages. The Indoor Air Quality (IAQ) management plan must be established and implemented in the ongoing basis to ensure the health of the occupants are safeguarded. As part of the plan, the practice to conduct an IAQ assessment once every 3 years is recommended to ensure the health and well-being of the occupants are safeguarded.

Investigation on the use of graphene oxide as novel surfactant to stabilize weakly charged graphene nanoplatelets.

This paper presents a unique synergistic behavior between a graphene oxide (GO) and graphene nanoplatelet (GnP) composite in an aqueous medium. The results showed that GO stabilized GnP colloid near its isoelectric point and prevented rapid agglomeration and sedimentation. It was considered that a rarely encountered charge-dependent electrostatic interaction between the highly charged GO and weakly charged GnP particles kept GnP suspended at its rapid coagulation and phase separation pH. Sedimentation and transmission electron microscope (TEM) micrograph images revealed the evidence of highly stable colloidal mixtures while zeta potential measurement provided semi-quantitative explanation on the mechanism of stabilization. GnP suspension was confirmed via UV-vis spectral data while contact angle measurement elucidated the close resemblance to an aqueous solution indicating the ability of GO to mediate the flocculation prone GnP colloids. About a tenfold increase in viscosity was recorded at a low shear rate in comparison to an individual GO solution due to a strong interaction manifested between participating colloids. An optimum level of mixing ratio between the two constituents was also obtained. These new findings related to an interaction between charge-based graphitic carbon materials would open new avenues for further exploration on the enhancement of both GO and GnP functionalities particularly in mechanical and electrical domains.

Basic effects of pulp refining on fiber properties--a review.

The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented.