3D-printed miniaturized fluidic tools in chemistry and biology.

3D printing (3DP), an additive manufacturing (AM) approach allowing for rapid prototyping and decentralized fabrication on-demand, has become a common method for creating parts or whole devices. The wide scope of the AM extends from organized sectors of construction, ornament, medical, and R&D industries to individual explorers attributed to the low cost, high quality printers along with revolutionary tools and polymers. While progress is being made but big manufacturing challenges are still there. Considering the quickly shifting narrative towards miniaturized analytical systems (MAS) we focus on the development/rapid prototyping and manufacturing of MAS with 3DP, and application dependent challenges in engineering designs and choice of the polymeric materials and provide an exhaustive background to the applications of 3DP in biology and chemistry. This will allow readers to perceive the most important features of AM in creating (i) various individual and modular components, and (ii) complete integrated tools.

Chemical characteristics of aerosols and trace gas distribution over North and Central India.

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 µg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 µg m(-3)) and in rural areas (44 ± 22 µg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 µg m(-3) and 4 to 11 µg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.

Study of temporal variation in ambient air quality during Diwali festival in India.

The variation in air quality was assessed from the ambient concentrations of various air pollutants [total suspended particle (TSP), particulate matter < or =10 microm (PM(10)), SO(2), and NO(2)] for pre-Diwali, Diwali festival, post-Diwali, and foggy day (October, November, and December), Delhi (India), from 2002 to 2007. The extensive use of fireworks was found to be related to short-term variation in air quality. During the festival, TSP is almost of the same order as compared to the concentration at an industrial site in Delhi in all the years. However, the concentrations of PM(10), SO(2), and NO(2) increased two to six times during the Diwali period when compared to the data reported for an industrial site. Similar trend was observed when the concentrations of pollutants were compared with values obtained for a typical foggy day each year in December. The levels of these pollutants observed during Diwali were found to be higher due to adverse meteorological conditions, i.e., decrease in 24 h average mixing height, temperature, and wind speed. The trend analysis shows that TSP, PM(10), NO(2), and SO(2) concentration increased just before Diwali and reached to a maximum concentration on the day of the festival. The values gradually decreased after the festival. On Diwali day, 24-h values for TSP and PM(10) in all the years from 2002 to 2007 and for NO(2) in 2004 and 2007 were found to be higher than prescribed limits of National Ambient Air Quality Standards and exceptionally high (3.6 times) for PM(10) in 2007. These results indicate that fireworks during the Diwali festival affected the ambient air quality adversely due to emission and accumulation of TSP, PM(10), SO(2), and NO(2).

A flowcytometric method for evaluation of acid secretion from isolated rat gastric mucosal cells.

Studies on the gastric proton pump are mostly performed on the H(+), K(+)-ATPase enzyme in the microsomal preparation or by aminopyrine accumulation in the gastric parietal cells. H(+), K(+)-ATPase activity is estimated by both spectrophotometric and fluorimetric methods. In the present study, quenching or augmentation in acridine orange (AO) fluorescence was monitored on a flowcytometer in rat gastric mucosal cells. Rat gastric mucosal cells were isolated by the standard pronase--EDTA method. The effect of oleic acid, a proton pump inhibitory was evaluated on gastric parietal cell activity and was compared with its effect on proton transport, H(+), K(+)-ATPase, and p-nitrophenyl phosphatase (p-NPPase) activity in gastric microsomes. In addition, the effect of histamine and carbachol, gastric acid release inducers, was also investigated by flowcytometry in isolated parietal cells. Histamine and carbachol, in a dose-dependent manner, stimulated acid release from isolated gastric cells. Oleic acid also dose-dependently inhibited the basal and stimulated acid release from the cells, as well as in all three enzyme preparations associated with gastric proton pump activity. Thus, the results suggest that flowcytometric method might be used to study basal, as well as stimulated, proton pump activity in isolated gastric parietal cells.

Frequency- and time-dependent effects of fendiline on action potentials of guinea pig papillary muscle.

The action of fendiline on cardiac electrical activity was investigated in guinea pig papillary muscle by monitoring frequency- and time-dependent changes in membrane potential, action potential (AP) configuration and conduction velocity. Isolated guinea pig papillary muscles driven at 0.1 to 3 Hz showed a concentration-dependent reduction of +Vmax, overshoot, and AP duration at -20mV (APD20) in the presence of fendiline (1-320 microM), reflecting inhibition of Na+ and L-type Ca2+ channels, respectively. No significant change in resting potential and AP duration at 90% repolarization (APD90) were observed. Inhibition of +Vmax and APD20 was more prominent at higher frequency of stimulation (2 Hz) than at lower ones (0.2 Hz), demonstrating frequency-dependent block of Na+ and Ca2+ channels including an open channel block. A good relationship between changes in +Vmax and APD20 suggested some commonality in the mechanism of inhibition of Na+ and Ca2+ channels by fendiline. Time-dependence of effects of fendiline, observed in presence of bolus dose (200 microM), showed an earlier onset of inhibition of +Vmax and APD20, particularly at higher frequencies. Missed beats and conduction block also appeared earlier in preparations driven at higher frequency. These findings suggest a frequency-dependent (and open channel) block of Na+ and Ca2+ channels by fendiline, leading to inhibition of fast and slow conduction in addition to its reported inactivated Ca2+ channel block.

Effect of nitric oxide modulators on pylorus-ligation-induced ulcers in the rat.

In the present investigation, the effect of nitric oxide (NO) modulators on pylorus-ligation-induced gastric ulcers in rats was studied. Sodium nitroprusside (SNP, 1 mg kg-1), a NO donor, l-arginine (l-Arg, 300 mg kg-1), the NO precursor, nitro-l-arginine methyl ester (l-NAME), a nitric oxide synthase (NOS) inhibitor and lipopolysaccharide (LPS, 3 mg kg-1), a NOS inducer have been administered prior to pylorus ligation. The effects of these interventions on the gastric mucosal nitrite content, the incidence of ulcers, the ulcer index, the volume of gastric secretions and the free and total acidity 4 h after pylorus ligation were investigated. SNP, l-Arg and LPS pretreatment increased the mucosal nitrite contents and protected the animals against pyloric-ligation-induced increase in acidity and ulcer index. However, inhibition of NOS activity by l-NAME (10 mg kg-1) decreased the nitrite content and augmented the ulcer-induced increase in the gastric acid contents. Coadministration of l-Arg with l-NAME prevented the l-NAME-induced changes. Interventions which increased the mucosal nitrite content were found to be protective against ulcers. However, the NOS inhibitor l-NAME decreased mucosal nitrite levels and was ulcerogenic. Results obtained thus indicate the protective effect of NO on the pyloric-ligation-induced ulcers in the rat.