Quantitative Analysis of Steel using Laser-Induced Breakdown Spectroscopy and Chemometrics

Peer reviewed: NoNRC publication: Ye

Laser-induced fluorescence detection of lead atoms in a laser-induced plasma: an experimental analytical optimization study

The combination of the laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) techniques was investigated to improve the limit of detection (LOD) of trace elements in solid matrices. The influence of the main experimental parameters on the LIF signal, namely the ablation fluence, the excitation energy, and the inter-pulse delay, was studied experimentally and a discussion of the results was presented. For illustrative purpose we considered detection of lead in brass samples. The plasma was produced by a Q-switched Nd:YAG laser and then re-excited by a nanosecond Optical Parametric Oscillator (OPO) laser. The experiments were performed in air at atmospheric pressure. We found out that the optimal conditions were obtained for our experimental set-up using relatively weak ablation fluence of 2-3 J/cm\ub2 and an inter-pulse delay of abuot 5-10 \ub5s. Also, a few tens of microjoules was typically required to maximize the LIF signal. Using the LIBS-LIFS technique, a single-shot LOD for lead of about 1.5 part per million (ppm) was obtained while a value of 0.2 ppm was obtained after accumulating over 100 shots. These values represent an improvement of about two orders of magnitude with respect to LIBS.On a \ue9tudi\ue9 la combinaison de la spectroscopie laser-plasma (SLP) et de techniques de fluorescence induite par laser (FIL) afin d\u2019am\ue9liorer la limite de d\ue9tection (LD) d\u2019\ue9l\ue9ments pr\ue9sents sous forme de trace dans des matrices solides. On a \ue9tudi\ue9 exp\ue9rimentalement l\u2019influence des principaux param\ue8tres exp\ue9rimentaux sur le signal de FIL, \ue0 savoir la fluence d\u2019ablation, l\u2019\ue9nergie d\u2019excitation et le d\ue9lai entre impulsions. On pr\ue9sente une discussion des r\ue9sultats. \uc0 des fins de d\ue9monstration, on a \ue9tudi\ue9 la d\ue9tection du plomb dans des \ue9chantillons de laiton. Le plasma \ue9tait produit gr\ue2ce \ue0 un laser Nd/YAG d\ue9clench\ue9, puis r\ue9-excit\ue9 au moyen d\u2019un laser \ue0 oscillateur param\ue9trique optique (OPO) nanoseconde. Les exp\ue9riences ont \ue9t\ue9 r\ue9alis\ue9es dans l\u2019air \ue0 pression atmosph\ue9rique. On a trouv\ue9 qu\u2019avec notre dispositif exp\ue9rimental les conditions optimales \ue9taient obtenues en utilisant une fluence d\u2019ablation relativement faible de 2\u20133 J/cm2 et un d\ue9lai entre impulsions d\u2019environ 5-10 \u3bcs. On a aussi trouv\ue9 que quelques dizaines de microjoules \ue9taient typiquement requis pour maximiser le signal de FIL. Gr\ue2ce \ue0 la technique de SLP/SFIL, on a obtenu une limite de d\ue9tection par impulsion pour le plomb d\u2019environ 1,5 partie par million (ppm), et une limite de 0,2 ppm a \ue9t\ue9 obtenue apr\ue8s accumulation du signal de 100 impulsions. Ces valeurs repr\ue9sentent une am\ue9lioration d\u2019environ deux ordres de grandeur par rapport \ue0 celles de la SFIL.Peer reviewed: YesNRC publication: Ye

The grapevine gene nomenclature system

Grapevine (Vitis vinifera L.) is one of the most important fruit crops in the world and serves as a valuable model for fruit development in woody species. A major breakthrough in grapevine genomics was achieved in 2007 with the sequencing of the Vitis vinifera cv. PN40024 genome. Subsequently, data on structural and functional characterization of grape genes accumulated exponentially. To better exploit the results obtained by the international community, we think that a coordinated nomenclature for gene naming in species with sequenced genomes is essential. It will pave the way for the accumulation of functional data that will enable effective scientific discussion and discovery. The exploitation of data that were generated independently of the genome release is hampered by their heterogeneous nature and by often incompatible and decentralized storage. Classically, large amounts of data describing gene functions are only available in printed articles and therefore remain hardly accessible for automatic text mining. On the other hand, high throughput "Omics" data are typically stored in public repositories, but should be arranged in compendia to better contribute to the annotation and functional characterization of the genes

Monitoring of Manufacturing Changes and Formulation Excipients on Solid Oral Dosage Forms of Furosemide Using Chemometrics and Laser-Induced Breakdown Spectroscopy (LIBS)

Peer reviewed: NoNRC publication: Ye

Association of mixed hematopoietic chimerism with elevated circulating autoantibodies and chronic graft-versus-host disease occurrence.

International audienceBACKGROUND: Use of a reduced-intensity conditioning regimen before an allogeneic hematopoietic cell transplantation is frequently associated with an early state of mixed hematopoietic chimerism. Such a coexistence of both host and donor hematopoietic cells may influence posttransplant alloreactivity and may affect the occurrence and severity of acute and chronic graft-versus-host disease (GVHD) as well as the intensity of the graft-versus-leukemia effect. Here we evaluated the relation between chimerism state after reduced-intensity conditioning transplantation (RICT), autoantibody production, and chronic GVHD (cGVHD)-related pathology. METHODS: Chimerism state, circulating anticardiolipin, and antidouble stranded DNA autoantibody (Ab) titers as well as occurrence of cGVHD-like lesions were investigated in a murine RICT model. RESULTS: We observed a novel association between mixed chimerism state, high levels of pathogenic IgG autoantibodies, and subsequent development of cGVHD-like lesions. Furthermore, we found that the persistence of host B cells, but not dendritic cell origin or subset, was a factor associated with the appearance of cGVHD-like lesions. The implication of host B cells was confirmed by a host origin of autoantibodies. CONCLUSION: Recipient B cell persistence may contribute to the frequency and/or severity of cGVHD after RICT

Advanced Genomic Data Mining

As data banks increase their size, one of the current challenges in bioinformatics is to be able to query them in a sensible way. Information is contained in differen

Snail accelerates cancer invasion by upregulating MMP expression and is associated with poor prognosis of hepatocellular carcinoma

We have previously demonstrated in an in vitro study that Snail increased the invasion activity of hepatoma cells by upregulating matrix metalloproteinase (MMP) gene expression. In the present study, we examined whether Snail gene expression correlates with cancer invasion and prognosis of patients with hepatocellular carcinoma (HCC). Quantitative reverse transcription–polymerase chain reaction (RT–PCR) was performed to evaluate Snail, E-cadherin, and MMP mRNA expressions in eight nodule-in-nodule tumours and 47 ordinary HCC tissues. In the nodule-in-nodule tumours, Snail expression significantly increased with tumour dedifferentiation (P=0.047). In the ordinary HCC tissues, Snail expression was significantly correlated with portal vein invasion (P=0.035) and intrahepatic metastasis (P=0.050); it also showed a significant correlation with MT1-MMP expression (r=0.572, P<0.001). In recurrence-free survival, the group with high Snail expression showed significantly poorer prognosis (P=0.035). Moreover, high Snail expression was an independent risk factor for early recurrence after curative resection. During the progression of HCC, Snail expression may be induced and accelerate invasion activity by upregulating MMP expression, resulting in portal invasion, intrahepatic metastasis, and poor prognosis