Identification of in Situ Progenitor Cell Features Contributing to Cartilage Repair and Strategies for Cartilage Repair Augmentation

Le cartilage articulaire hyalin recouvre l’extrémité des os longs. Sa capacité de guérison intrinsèque est faible puisqu’il n’est pas vascularisé. Suite à une blessure, la guérison n’a généralement pas lieu, ou demeure de faible amplitude. Une dégénérescence des lésions peut également survenir suite au relargage de cytokines et autres facteurs inflammatoires. Un déséquilibre entre les activités anaboliques et cataboliques peut éventuellement induire l’érosion du cartilage, l’exposition de l’os sous-jacent et l’ostéoarthrite. Les techniques de stimulation de la moelle osseuse sont une façon de stimuler la guérison du cartilage en perçant l’os situé sous les lésions du cartilage. Les canaux percés permettent aux cellules progénitrices qui se trouvent dans la moelle osseuse (bone marrow progenitor cells en anglais) de migrer vers les lésions. Ces cellules progénitrices se différencient et synthétisent un tissue de granulation qui sera remodelé en tissue de guérison. Les techniques de stimulation de la moelle osseuse sont beaucoup utilisées en clinique puisqu’elles sont simples et peu coûteuses à effectuer, que les patients se rétablissent rapidement après la chirurgie et qu’elles sont efficaces pour diminuer la douleur. Cependant, les bienfaits ressentis ne sont pas durables puisque le tissu de guérison est un tissue fibrocartilagineux qui ne possède pas les propriétés biologiques et mécaniques du cartilage hyalin. Les inconvénients les plus communs observés au cours d’études pré-cliniques et cliniques portant sur les techniques de stimulation de la moelle osseuse sont une guérison incomplète, une grande variabilité inter-individu, et des résultats insatisfaisants, surtout chez les individus plus âgés. Il a déjà été démontré dans des études pré-cliniques que l’emplacement de la lésion ainsi que l’âge de l’animal sont deux paramètres qui affectent grandement la guérison. Plus spécifiquement, chez le lapin, les lésions situées sur la trochlée guérissent mieux que les lésions situées sur le condyle fémoral médial, ce qui suggère que les cellules progénitrices de la moelle osseuse présentes aux deux emplacements ne possèderaient pas les mêmes propriétés biologiques intrinsèques. L’objectif de la première étude de cette thèse était de déterminer l’effet de l’emplacement et de l’âge de l’animal sur les propriétés biologiques intrinsèques des cellules progénitrices de la moelle osseuse. Pour ce faire, les propriétés biologiques des cellules isolées à partir de la trochlée et des condyles chez des lapins jeunes et âgés ont été caractérisées. Ensuite, puisque de précédentes études chez le lapin ont démontré qu’un perçage profond à 6 mm favorise la guérison du cartilage dans la trochlée en comparaison à un perçage peu profond, les propriétés biologiques de cellules progénitrices isolées à partir de la moelle métaphysaire (région profonde) et de la moelle épiphysaire (région peu profondes) ont été caractérisées. Deux méthodes d’isolation des cellules progénitrices ont été utilisées, soit la digestion enzymatique à la collagénase et la culture d’explants osseux. Pour chaque population de cellules progénitrices, le rendement cellulaire, le potentiel clonogénique et l’expression de différents marqueurs ont été déterminés in vitro. Le potentiel chondrogénique a, quant à lui, été déterminé en stimulant les cellules progénitrices avec un milieu de culture chondrogénique contenant de l’ascorbate, ITS et TGF-III. Enfin, le potentiel ostéogénique a été déterminé en stimulant les cellules progénitrices avec un milieu de culture ostéogénique contenant du dexamethasone, de la β-glycerophosphate et de l’ascorbate. Une comparaison entre les propriétés biologiques obtenues pour les cellules progénitrices provenant des condyles, de la trochlée profonde, ou de la trochlée peu profonde, pour les lapins jeune ou âgés et pour les cellules isolées par digestion enzymatique ou par culture d’explants a ensuite été effectuée. Selon les critères établis par l’International Society for Cell Therapy, les cellules progénitrices isolées lors de l’étude pouvaient être décrites comme une population de cellules souches mésenchymateuses. Les condyles avaient un faible rendement cellulaire en comparaison à la trochlée et les cellules progénitrices isolées à partir des condyles avaient également de faibles potentiels clonogénique et chondrogénique. En revanche, les cellules progénitrices isolées à partir de la trochlée possédaient un haut rendement cellulaire, des potentiels clonogénique et chondrogénique élevés et exprimaient beaucoup de glycosaminoglycanes et de collagène type II, deux molécules présentes dans le cartilage articulaire hyalin. Le site d’isolation ou l’emplacement était donc un facteur déterminant pour les propriétés biologiques des cellules progénitrices, ce qui suggère que le potentiel de guérison élevé observé dans la trochlée du lapin serait dû à la présence d’une population nombreuse de cellules progénitrices ayant un fort potentiel chondrogénique. L’âge des lapins s’est aussi avéré être un facteur important puisque le rendement cellulaire, l’expression de marqueurs pour cellules souches et la différenciation chondrogénique et ostéogénique étaient meilleurs chez les lapins jeunes que chez les lapins âgés. Enfin, il n’y avait pas de différence entre les cellules isolées par digestion enzymatique ou par culture d’explants. L’objectif de la deuxième étude de cette thèse était de déterminer s’il existe une corrélation entre les propriétés biologiques intrinsèques des cellules progénitrices de la moelle osseuse et la capacité de guérison du cartilage sus-jacent. Pour ce faire, un modèle bilatéral a été effectué chez 8 lapins. Pour chaque lapin, des lésions cartilagineuses ont été créées sur un genou à deux emplacements (la trochlée et le condyle fémoral médial) puis traitées par microperçage, tandis que l’autre genou demeurait intact. Après 3 semaines de guérison, les lapins ont été sacrifiés et des sections histologiques ont été récoltées du genou traité par microperçage afin d’évaluer la guérison. Parallèlement, les cellules progénitrices du genou intact ont été récoltées et leurs propriétés biologiques caractérisées tel que décrit ci-haut. Chez tous les lapins, la guérison induite par stimulation de la moelle osseuse était compromise dans le condyle fémoral médial, où très peu de tissu de guérison était présent après 3 semaines. En revanche, une guérison modérée à excellente était apparente dans la trochlée de 6 lapins sur 8, alors que 2 lapins ont été classifiés comme faisant partie d’un groupe ayant un plus faible potentiel de guérison. Tout comme pour la première étude, les cellules progénitrices de la trochlée avaient un meilleur rendement cellulaire et de forts potentiels clonogénique et chondrogénique que les cellules des condyles. Une variabilité inter-individu était également présente dans le cas des propriétés biologiques des cellules progénitrices. Les tissus de guérison de la trochlée ainsi que la matrice extracellulaire synthétisée par les cellules progénitrices isolées à partir de la trochlée contenaient une grande quantité de glycosaminoglycanes et de collagène type II. Des analyses statistiques ont permis de déterminer qu’il existait de fortes corrélations positives entre les propriétés intrinsèques des cellules progénitrices de la moelle osseuse et la capacité de guérison du cartilage sus-jacent. Les propriétés biologiques ayant le plus d’impact sur la guérison ont été identifiées. L’objectif de la troisième étude de cette thèse était de développer un modèle animal représentatif de la situation clinique, et d’y tester une nouvelle méthode de guérison. En clinique, les lésions du cartilage sont rarement détectées rapidement, ce qui complique le traitement. Une grande variabilité de la réponse et une guérison compromise sont également observées chez les patients plus âgés souffrant de lésions dégénératives chroniques. La rétraction du caillot sanguin qui remplit les lésions cartilagineuses suite au microperçage et sa perte subséquente sont une raison qui pourrait expliquer les résultats insatisfaisants observés en clinique. Il a été démontré que le chitosane permet d’inhiber la rétraction du caillot sanguin et, par le fait même, qu’il promeut la guérison du cartilage en ayant des effets sur le recrutement cellulaire, la vascularisation and le remodelage osseux. Le plasma riche en plaquettes (PRP) contient une concentration élevée de facteurs de croissance capables de stimuler le recrutement cellulaire et la différenciation chondrogénique. Il a été démontré que le chitosane favorise la stabilité du PRP et le relargage de facteurs de croissance. Un modèle de lésions cartilagineuses chroniques a d’abord été développé chez le lapin. Deux chirurgies était nécessaires pour effectuer ce modèle. Au cours de la première chirurgie, des lésions cartilagineuses bilatérales ont été induites dans la trochlée de 8 lapins et laissées sans traitement pendant 4 semaines afin qu’elles dégénèrent à un stade chronique. Au cours de la deuxième chirurgie, ces lésions cartilagineuses ont été traitées par microperçage et par l’implantation de chitosane lyophilisé solubilisé dans du PRP autologue, ou par injection de PRP seul, comme contrôle. Le tissu de guérison a été récolté après 2 mois et des sections histologiques ont permis d’évaluer la quantité et la qualité du tissu de guérison. La guérison osseuse ainsi que le remodelage osseux ont également été caractérisées par analyse micro-CT. Les implants chitosane-PRP favorisaient la guérison des lésions cartilagineuses chroniques comparées au PRP seul. La composition biochimique de la matrice cartilagineuse ressemblait plus à du cartilage hyalin en présence des implants chitosane-PRP. Finalement, l’analyse micro-CT démontrait que les implants chitosane-PRP favorisent le remodelage osseux mais que le phénomène est toujours en cours après 2 mois de guérison. En résumé, le contenu de cette thèse nous a permis d’identifier certaines variables liées à l’emplacement, au donneur et à l’âge qui expliqueraient partiellement la variabilité inter-individu et les résultats décevants parfois obtenus suite à une stimulation de la moelle osseuse. Le modèle de lésions chroniques décrit dans cette thèse contribuera grandement au développement de nouvelles techniques et de nouveaux produits pour favoriser la guérison du cartilage articulaire. Enfin, les implants chitosane-PRP étudiés au cours de cette thèse constituent une approche prometteuse qui pourrait éventuellement servir à soulager des patients souffrant de lésions chroniques ou dégénératives.----------ABSTRACT Articular cartilage is a thin layer of hyaline cartilaginous tissue covering the ends of long bones. Due to its avascular nature, it possesses very limited regeneration potential. In the event of an injury, the repair is either very limited or not initiated at all. As a result, cartilage lesions degenerate extensively under the influence of damaging cytokines and proinflammatory factors released. An imbalance in anabolic and catabolic activities continues to erode the cartilaginous surface exposing subchondral bone leading to osteoarthritis. Bone marrow stimulation (BMS) initiates repair by fracturing or drilling into subchondral bone. The channels created provide access to the underlying subchondral progenitor cells that are recruited into the defect. Granulation tissue thus formed undergoes a complex cascade of events to generate a repair tissue. BMS is considered a gold standard of cartilage repair strategies since it is easy, relatively less invasive with swift recovery, more economical and appreciable short-mid term relief. However, long term outcome is generally discouraging due to poor durability of repair tissue. The quality of repair tissue is generally fibrocartilagenous with inferior mechanical and biological characteristics compared to hyaline cartilage. The most common drawbacks of the procedure include incomplete regeneration, high inter-individual variability and poor repair outcome especially in older individuals in preclinical as well as clinical studies. Earlier studies have shown that defect location and animal age affect the cartilage repair outcome observed in vivo, suggesting a strong influence of biological characteristics of progenitor cells (Bone Marrow stem cells; BMSCs or mesenchymal stem cells; MSCs) present in subchondral bone. Specifically, rabbit trochlea showed a superior repair and chondrogenic potential compared to the medial femoral condyle. Inspired by these observations, we carried out a study for comprehensive analysis of progenitor cells present in the subchondral bone of condyle and trochlea in young and old rabbits in order to determine the influence of location and age on the properties of progenitor cells. Earlier we had found that drilling to 6 mm improves the repair outcome in rabbit trochlea possibly by providing access to metaphyseal marrow and thus higher progenitor cell population. As a result, MSCs were isolated from epiphyseal (trochlea upper) and metaphyseal (trochlea lower) regions of the trochlea. Collagenase-derived MSCs originated from collagenase digest of bone chips while the digested explants were subsequently cultured to obtain explant-derived MSCs via cell outgrowth. In vitro characterization assays were used to determine the cell yield, clonogenic potential and surface marker expression profile. Chondrogenic differentiation was stimulated using pellets of condylar and trochlear MSCs in the presence of chondrogenic media, rich in chondrogenic stimulating factors such as ascorbate, insulin-transferrin-selenium (ITS) and TGF-βIII. Finally, MSCs were differentiated into osteogenic lineage in presence of osteogenic media containing osteogenic stimulants such as dexamethasone, β-glycerophosphate and ascorbate. The aforementioned MSC characteristics were compared for trochlea vs. condyle, old vs. young and collagenase- vs. explant-derived cultures. MSCs isolated from distal femur epiphyseal bone had stem cell characteristics and fulfilled the stem cell criteria outlined by International Society for Cell Therapy. Location was an important factor influencing the properties of MSCs indicated by low cell yield, clonogenic potential and inferior chondrogenic potential of condylar cells. Results showed that rabbit trochlear vs. condylar subchondral bone yielded a greater number of progenitors with superior cartilaginous matrix expression under chondrogenic conditions suggesting higher intrinsic capacity for cartilage repair compared to condylar subchondral bone. Trochlear MSCs displayed superior chondrogenic differentiation evidenced by higher glycosaminoglycan (GAG) and collagen type II deposition. Age of the donor was an additional factor with significant bearing on the inherent properties of MSCs since growth rate, cell yield, expression of stem cell markers and osteogenic differentiation were found to be significantly superior in younger animals. As expected, no significant difference was observed between collagenase- and explant-derived cultures. Continuing our exploration of the mechanisms underlying variability in BMS procedure, we carried out the next study to verify if the cartilage repair outcome in condyle and trochlea correlated with the pre-existing properties of progenitor cells present in these two sites. A bilateral rabbit model was used to test this hypothesis. For each rabbit, full thickness acute defects were created in one knee and treated by BMS by microdrilling, while the second knee was left intact. Animals were sacrificed 3 weeks later and transverse sections of repair tissue from the treated knee were used to analyze the quality and quantity of repair macroscopically and by safranin- O (Saf-O) and immunostaining. At the time of animal sacrifice, distal femurs were separated and MSCs were isolated from condylar and trochlear regions of the intact contralateral knee for biological characterization of cell yield, clonogenic potential, cell surface marker profile and differentiation potency. BMS induced inferior cartilage repair in condyles of all donors studied further underlining the implication of location in influencing repair outcome. Macroscopic examination revealed extremely poor fill in condylar defects. In contrast, moderate to excellent fill was observed in six out of eight trochlear defects. This led us to identify a donor-dependent variability in repair outcome and the donors were classified as good trochlear responders and poor trochlear responders. In another observation, trochlear MSCs were characterized by increased cell yield, higher clonogenic potential and superior chondrogenic potential. Histopathological analysis indicated better matrix composition, rich in GAG and collagen type II in trochlea both in vivo and in vitro. Donor related variability in repair outcome was also observed in vitro through biological characterization of MSCs. Statistical analysis provided substantial evidence to identify strong, positive location- and donor-dependent correlations between inherent properties of MSCs and cartilage repair outcome in condyle and trochlea and factors with maximum influence on the repair outcome were identified. By this stage, it became imperative to seek after a clinically relevant application of our understanding based on current and past findings. Cartilage lesions are rarely detected in early stages, unfortunately reducing the efficacy of BMS procedure. Unpredictable, highly variable repair of poor quality is observed in degenerative defects, especially in older patients. Platelet-mediated retraction of the blood clot that fills cartilage lesions following BMS is believed to be one underlying cause of inferior quality and durability of repair tissue. Chitosan inhibits this blood clot shrinkage and leads to the formation of a voluminous, adherent and stable clot and thereby enhances cartilage repair by promoting cell recruitment, transient vascularization and subchondral bone remodeling. Platelet-rich-plasma (PRP) contains a 2-10 fold concentration of growth factors and cytokines and has been shown to improve recruitment and chondrogenic potential of subchondral MSCs. Chitosan increases the stability of PRP and promotes the release of platelet-derived growth factors in a more sustained manner. Using a more clinically relevant chronic defect model, we tested the efficacy of implants composed of freeze-dried chitosan solubilized in PRP in improving marrow stimulated cartilage repair outcome compared to BMS augmented with just PRP. Two surgeries were performed in skeletally mature rabbits to create a bilateral trochlear defect model. Defects created in the first surgery were allowed to degenerate over 4 weeks and repaired in a second surgery by BMS. Treatments included BMS augmented with chitosan/PRP implants in one knee and BMS with PRP in the other knee. Repair tissue was harvested 2 months later and transverse sections were used to characterize the quality and quantity of repair by assessing the GAG and coll-II deposition. Subchondral bone repair was analysed by micro-CT. Augmentation of BMS with freeze-dried chitosan/PRP implants in chronic defects improved cartilage repair compared to PRP by increasing quantity and quality of repair tissue and promoting subchondral bone repair. Matrix composition was improved in presence of chitosan/PRP indicated by increased GAG and collagen deposition. MicroCT analysis showed further evidence of increased, albeit incomplete, subchondral bone remodeling induced by chitosan/PRP. In summary, these studies led us to recognize significant donor-, age- and location-dependent variability which might help in understanding the mechanism underneath the unpredictability and inter-individual variability observed with BMS. Needless to say, these observations would be extremely valuable in improving the consistency, durability and quality of BMS repair procedure. Moreover, the innovative chronic model studied here is expected to make significant contributions in progress of cartilage repair field. Finally, chitosan/PRP implants investigated in this research are a promising approach to treat chronic cartilage lesions and could eventually provide relief to osteoarthritic patients with challenging, degenerative defects

Neonatal outcome in early term and late term pregnancy

Background: Full-term neonates born between 37- and 41-weeks’ gestational age have been considered a homogeneous, low-risk group. However, recent evidence from studies has pointed toward increased NICU admissions and morbidity associated with births (37-38 weeks) compared with term neonates (39-41 weeks). The objective of this study was to compare the short-term morbidity of early-term vs term neonates in a county-based birth cohort using the primary objective of admission to a neonatal intensive care unit (NICU) or neonatology service. Methods: Retrospective observational population-based 2 year birth cohort study at Department of Obstetrics and Gynecology GSVM Medical College, Kanpur. All full-term live births comprised the birth cohort; this information was obtained from the hospitals’ perinatal databases, and data pertaining to NICU, or neonatology service admissions were extracted from individual medical records.  Gestational age of early term (37 0/7-38 6/7 weeks) verses term (39 0/7-4 10/7 weeks). Admission to the NICU or neonatology service. Results: There were 17,132 live births during the 2 year period, of which 13679 had a gestational age between 37 and 41 weeks. Of all live births, 6204 (45.3%) were early term. Compared with term infants, early-term neonates had significantly higher risks for the following: hypoglycaemia (29.9% verses 14.7%), NICU or neonatology service admission (20.9% vs12.05 %), need for respiratory support (36.8% verses 29.9%), treatment with intravenous antibiotics [39.4% verses 25. Delivery by caesarean section was common among early-term births (45.9%)]. Conclusions: Early-term births are associated with high neonatal morbidity and with NICU or neonatology service admission. Evaluation of local prevalence data will assist in implementation of specific preventive measures and plans, as well as prioritize limited health care resources

Study of association of socio-demographic characteristics with the knowledge about sex determination and preconception and prenatal diagnostic technique act among pregnant women

Background: Preconception and prenatal diagnostic technique Act was amended in year 2003 which provides for prohibition of sex selection before and after conception and for regulation of prenatal diagnostic technique.Methods: A cross sectional study was carried out in antenatal ward of GSVM Medical College Kanpur during the period of January to December 2019. A total of 2500 pregnant women were included and predesigned and pretested questionnaire was used to get information regarding socio-demographic details of pregnant women. They were asked regarding the knowledge and attitude towards the PC-PNDT Act. Data were collected and analyzed using Microsoft excel and SPSS-12. Results: In the present study, out of 2500 women, 2125 (85%) knew about sex determination while 125 (5%) knew about PNDT Act. There was significant association of occupation, education and annual income with knowledge. Majority of women know about PC-PNDT act from health staff and ultrasonography was the main technique they know to detect sex determination. Conclusions: The falling ratio of girl child is a matter of grave concern. Effective implementation of the PNDT Act in addition to spreading awareness about this act among people is the need of the hour. Educating the community will prevent the decline in sex ratio and female feticide through PC-PNDT Act

Effect of anaemia on maternal and fetal outcome: an observational study

Background: Anaemia in pregnancy is a globally health-related issue that affects both mothers and their new-born. Hence an observational study to see the effect of anaemia on maternal and foetal outcome was conducted. Methods: 15024 mothers coming in OPD or IPD in past 4 years were recruited and their haemoglobin measured. Descriptive statistics was used for baseline characteristics. This observational study was conducted in department of obs and gynae, GSVM Medical College Kanpur from August 2018 to August 2022. All the data gathered was processed by SPSS version 25. Results: The main outcomes included 4 maternal outcomes (postpartum haemorrhage, shock, ICU admission, and maternal mortality) and 4 neonatal outcomes (foetal growth restriction, birth weight, NICU admission, stillbirth). 60.03% of the mothers were anaemic in our study. Maternal and foetal complications were more in anaemic than non-anaemic mothers with incidence of PPH, shock, ICU admission, and maternal mortality being 14.07%, 11.33% ,4.30 and 1.31% respectively than non-anaemic mothers with incidence of 11.22%, 7.26%, 1.76%, and 7.28% respectively. Foetal outcome was also poorer in anaemic mothers with incidence of FGR, LBW, NICU admission, Still birth being 3.15%, 8.85%, 12.96%, and 1.09% higher than non-anaemic group with incidence being 1.80%, 3.43%, 9.75%, and 0.30 % respectively. Conclusions: This observational study provides valuable insights into the effect of anaemia on both maternal and foetal outcomes. It emphasizes the importance of early detection and management of anaemia to mitigate the risks associated with this condition

Salivary uric acid as a non-invasive marker of early onset preeclampsia

Background: Preeclampsia is one of the most common complications in pregnancy and is a major cause of maternal and perinatal morbidity and mortality. Early prediction of preeclampsia is crucial in proactive management of the patient. Uric acid is a biomarker of hypertension. Methods: A prospective study was done on 200 pregnant females in their first or early second trimester of pregnancy and were followed till one week of delivery or termination of pregnancy. After taking socio-demographic details, detailed medical and obstetric history was taken. Blood pressure of the patients was routinely measured and mean arterial pressure was calculated. Blood and saliva samples were taken and were analysed following standard protocol for serum and salivary uric acid levels respectively. Participants were classified into normotensive and preeclampsia groups depending on the criteria met. Results: Preeclampsia group participants had significantly more adverse and feto-maternal outcomes. Salivary uric acid is a promising diagnostic predictor of preeclampsia in pregnant women by the virtue of being a non-invasive investigation with cut off value 4.86 mg/dl having a sensitivity of 70.8%, specificity of 45.7% and a PPV of 81.3%. Salivary uric acid level and mean arterial pressure were found to be better predictors of preeclampsia as compared to salivary uric acid level. Conclusions: Salivary uric acid is a reliable predictor of preeclampsia in pregnant females in first and early second trimester of pregnancy. Further largescale studies are warranted to establish an accurate cut off value with good diagnostic properties for Indian population

New emerging rare-earth free yellow emitting 2D BCNO nanophosphor for white light emitting diodes

We have demonstrated a new emerging rare-earth free highly-efficient two dimensional (2D) boron carbon oxynitride (BCNO) yellow emitting nanophosphor with high quantum efficiency for white light emitting diode (WLED) devices. This BCNO nanophosphor exhibits 2D layered structures analogous to hexagonal BN phase. Further, the EELS and XPS results confirm the nanophosphor consisted of B, C, N and O elements. The BCNO nanophosphor shows a broad highly intense yellow emission band centered at 580 nm corresponding to 470 nm excitation wavelength with a quantum efficiency approaching 89%. This novel nanophosphor with strong emission has subsequently been integrated to chip on board (CoB) based blue LEDs in order to fabricate WLEDs devices with a color rendering index of 92. Low color temperature (4899) and better CIE color coordinates (x = 0.3496, y = 0.3679) of a fabricated WLEDs device supports a 2D BCNO nanophosphor that could be an exceptional choice for CoB based WLEDs. Hence, our method provides a facile synthesis of rare-earth free 2D lightweight BCNO nanophosphor and its integration with CoB based blue LEDs for next generation advanced solid state white light applications

Probing on green long persistent Eu2+/Dy3+ doped Sr3SiAl4O11 emerging phosphor for security applications

Herein, a novel green emitting long-persistent Sr(3)SiAl(4)O(1)1:Eu2+/Dy3+ phosphor was synthesized in a single phase form using facile solid state reaction method under the reducing atmosphere of 10% H-2 and 90% N-2. The resulting phosphor exhibits hyper-sensitive strong broad green emission, peaking at 510 nm upon 340 nm excitation wavelength, which is attributed to the 4f(6)5d(1)-4f(7) transitions of emission center of europium (Eu2+) ions. Moreover, the incorporation of dysprosium (Dy3+) ions, which act as effective hole trap centers with appropriate depth, largely enhances the photoluminescence characteristics and greatly improves the persistent intense luminescence behavior of Sr3SiAl4O11:Eu2+/Dy3+ phosphor under ultraviolet (UV) excitation. In addition, with the optimum doping concentration and sufficient UV excitation time period, the as-synthesized phosphor can be persisted afterglow for time duration similar to 4 h with maximum luminescence intensity. Thus, these results suggest that this phosphor could be expected as an ultimate choice for next generation advanced luminescent materials in security applications such as latent finger-marks detection, photo-masking induced phosphorescent images, and security code detection

A protective role for nitric oxide and salicylic acid for arsenite phytotoxicity in rice (Oryza sativa L.)

The authors are thankful to Director, CSIR-National Botanical Research Institute (CSIR-NBRI), Lucknow for the facilities and for the financial support from the network projects (CSIR-INDEPTH), New Delhi, India. APS is thankful to CSIR New Delhi, India respectively, for the award of Research Associateship. RDT is gratefully thankful to Award of Emeritus Scientist (CSIR). GD is thankful to SERB-DST, New Delhi for award of NPDF. AK is thankful to UGC for award of DSKPDF. Award of Fast Track Scientist to SM from DST is gratefully acknowledged. We are also thankful to Mr. Dilip Chakraborty for technical assistance.Peer reviewedPostprin

Utilization of RHA in development of green composite material using RSM

In the present investigation, rice husk waste from rice mill was utilized in the development of aluminum based green metal matrix composite. Response surface methodology (RSM) was employed to develop green metal matrix composite by considering tensile strength as a response. Rice husk ash (RHA) was used as primary reinforcement material and B4C was used as a secondary reinforcement material in the development of composite. Microstructure results showed a uniform distribution of RHA and B4C in aluminum based matrix material. The optimum combination of reinforcement parameters was found to be RHA weight percentage of 7.8%, RHA preheats temperature of 231.12∘C, B4C preheats temperature of 435.24∘C and B4C wt.% of 6.67% respectively to achieve a tensile strength of 249.867 MPa

The association of breast feeding and nutritional status of children 13-36 months of age /

Previous studies failed to report benefits of prolonged breast feeding on nutritional status. A nationally representative sample of 1411 children from Sri Lanka (1987) was used to compare breast feeders versus non breast feeders, as well as duration of breast feeding, through multivariate analyses for height-for-age, weight-for-age and weight-for-height z-scores. Analyses of interaction showed prolonged breast feeding to be advantageous among children of working mothers, and children from households using an unimproved water supply. For example, children 35 months of age, breast fed for 24 versus 8 months were 0.9 centimetres (95% confidence interval; +0.0, 1.8) taller if mothers worked and 420 grams (140, 690) heavier if households used an unimproved water supply. Among uneducated mothers breast fed children were 1.3 cm (2.2, 3.3) shorter than non breast fed children. Prolonged breast feeding should be encouraged as it is advantageous for the nutritional status of certain subgroups of children older than 12 months of age