Matrix Metalloproteinase-1 and -9 in Human Placenta during Spontaneous Vaginal Delivery and Caesarean Sectioning in Preterm Pregnancy

Preterm birth is a major public health problem in terms of loss of life, long-term and short term disabilities worldwide. The process of parturition (both term and preterm) involves intensive remodelling of the extracellular matrix (ECM) in the placenta and fetal membranes by matrix metalloproteinases (MMPs). Our previous studies show reduced docosahexaenoic acid (DHA) in women delivering preterm. Further omega 3 fatty acids are reported to regulate MMP levels. This study was undertaken to examine the placental levels of MMPs and their association with placental DHA levels in women delivering preterm. The levels of MMP-1 and MMP-9 in 74 women delivering preterm (52 by spontaneous vaginal delivery and 22 by caesarean sectioning) and 75 women delivering at term (59 by spontaneous vaginal delivery and 16 by caesarean sectioning) were determined by enzyme-linked immunosorbent assay (ELISA) and their association with placental DHA was studied. Placental MMP-1 levels were higher (p<0.05) in women delivering preterm (both by spontaneous vaginal delivery and caesarean sectioning) as compared to those delivering at term. In contrast, placental MMP-9 levels in preterm pregnancies was higher (p<0.05) in women with spontaneous vaginal delivery while lower (p<0.05) in women delivering by caesarean sectioning. Low placental DHA was associated with higher placental MMP-9 levels. Our study suggests a differential effect of mode of delivery on the levels of MMPs from placenta. Further this study suggests a negative association of DHA and the levels of MMP-9 in human placenta although the mechanisms need further study

Optimization of hybrid InAs stranski krastanov and submonolayer quantum dot heterostructures and its effect on photovoltaic energy conversion efficiency in near infrared region

We are introducing here hybrid Stranski Krastanov (SK) on submonolayer (SML) quantum dot (QD) heterostructure for improved photovoltaic energy conversion in the near infrared (NIR) region. Vertically coupled QDs with lower amount of cumulative strain make it a promising competitor of homogeneous QD families. Still now no research groups have reported such heterogeneously coupled QD based quantum dot solar cell (QDSC) for better NIR harvesting. In the present study, we are emphasizing on growth optimization of such heterogeneous QD family. Ex situ modulation of interdot electronic interaction has been explored by rapid thermal annealing (RTA). The sample with 0.1 ML/s growth rate and 7.5 nm GaAs barrier comes out as the best coupled configuration with improved thermal stability. This particular configuration is incorporated into a P-I-N QDSC, which shows broader and enhanced external quantum efficiency at NIR region. In addition, RTA at 650 and 700 degrees C shows a drastic enhancement of quantum efficiency due to the annihilation of as grown defects and trap centers

Improved near infrared energy harvesting through heterogeneously coupled SK on SML quantum dot heterostructure

Near Infra Red (NIR) energy harvesting is one of the advanced strategies to improve the overall performance of new generation solar photovoltaics. We introduce here a new heterogeneously coupled Stranski Krastanov (SK) on Submonolayer (SML) quantum dot (QD) heterostructure, which is capable of enhanced energy conversion efficiency in that typical spectral range. The coupling in the proposed structure has been optimized by varying the growth rate and the barrier thickness between seed SML and top SK QDs. The optimal configuration has been incorporated into a quantum dot solar cell (QDSC). The carrier transitions in this hybrid QD assembly have been investigated through luminescence spectroscopy. An existence of carrier tunnelling between SML and SK QDs has been revealed from the photoluminescence and the photoluminescence excitation spectroscopy. The unique configuration of such coupled QDs shows the presence of resonating energy states. These phenomena ameliorate the absorption efficiency in the NIR regime with increased photoexcited carrier lifetime, which has been reflected in the external quantum efficiency