14 research outputs found
CO2 fixation by seaweeds and their role in De-acidifying Ocean - An experimental approach
CO2 fixation by seaweeds and their role in De-acidifying Ocean - An experimental approac
Role of seaweeds in neutralizing the impact of seawater acidification- A laboratory study with beached shells of certain bivalves and spines of a sea urchin
Ocean acidification is one of the major impacts of climate
change in sea which is manifested by the decrease in hydrogen
ion concentration (pH) of seawater mainly due to increased
uptake of CO2 and reduction in carbonate ions. This is a report
on the dissolution rate of dead shells of four marine bivalves
and spines of a sea urchin when treated with different levels of
CO2 dissolved in seawater for 48 hours which was measured
gravimetrically. Dissolution of dead shells expressed as
reduction in shell weight was directly proportional to the
concentration of dissolved CO2. Live thallus of green seaweed
Chaetomorpha antennina did reduce the magnitude of
dissolution rates (P<0.05) of all the shells and spines
considerably as well as the change in pH of ambient seawater
due to the addition of CO2. The remedial property of seaweeds
was more effective at lower concentrations of dissolved CO2.
The induced change in pH was restored by green seaweed only
at concentrations above 250 ppm. Although we noticed strong
impact of dissolved CO2 on the dead shells of Mactrinula
plicataria even at 100 ppm level, the remedial action by the
green seaweed was maximum in Siliqua radiata followed by
Perna viridis. Results of this laboratory study shows the positive
role of seaweeds in neutralizing the acidification impacts
Not Available
Not AvailableOcean acidification is one of the major impacts of climate
change in sea which is manifested by the decrease in hydrogen
ion concentration (pH) of seawater mainly due to increased
uptake of CO2 and reduction in carbonate ions. This is a report
on the dissolution rate of dead shells of four marine bivalves
and spines of a sea urchin when treated with different levels of
CO2 dissolved in seawater for 48 hours which was measured
gravimetrically. Dissolution of dead shells expressed as
reduction in shell weight was directly proportional to the
concentration of dissolved CO2. Live thallus of green seaweed
Chaetomorpha antennina did reduce the magnitude of
dissolution rates (P<0.05) of all the shells and spines
considerably as well as the change in pH of ambient seawater
due to the addition of CO2. The remedial property of seaweeds
was more effective at lower concentrations of dissolved CO2.
The induced change in pH was restored by green seaweed only
at concentrations above 250 ppm. Although we noticed strong
impact of dissolved CO2 on the dead shells of Mactrinula
plicataria even at 100 ppm level, the remedial action by the
green seaweed was maximum in Siliqua radiata followed by
Perna viridis. Results of this laboratory study shows the positive
role of seaweeds in neutralizing the acidification impacts.Not Availabl
Effects of reflow profile and miniaturisation on integrity of solder joints in surface mount chip resistor
Integrity of solder joints of components in an electronic device is critical to the device reliability. Miniaturisation manufacturing trend in electronic products development has continued to challenge the shear strength of the solder joints in these devices and necessitates implementation of optimal reflow profile to achieve maximum strength of the joints. This research proposes optimal parameter combination of reflow profile factors which demonstrate potential of delivering maximum shear strength of solder joint. The Taguchi design of experiment (DoE) is employed to generate eight orthogonal array designs of L24 of reflow profiles. The factors/parameters investigated are preheat gradient, time above liquidus (TAL), peak temperature and cooling rate. Three test vehicles of varying solder joint sizes are made from R1206, R0805 and R0603 resistors. Reflow profile number 3 constituting 1.2 °C/s preheat, 45 s TAL, 245 °C peak temperature and 60% cooling rate is optimal because it yielded joints with highest strength and circa 4 µm thickness of intermetallic compound (IMC). Solder joint shear strength decreases with decrease in size of lead-free joint irrespective of reflow profile implemented. These results will be useful to electronic packaging and reliability engineers faced with challenges of improving device operational mechanical performance in the continuing product miniaturisation trend