26 research outputs found
Nanoscale Metallic Iron for Environmental Remediation: Prospects and Limitations
The amendment of the subsurface with nanoscale metallic iron particles
(nano-Fe0) has been discussed in the literature as an efficient in situ
technology for groundwater remediation. However, the introduction of this
technology was controversial and its efficiency has never been univocally
established. This unsatisfying situation has motivated this communication whose
objective was a comprehensive discussion of the intrinsic reactivity of
nano-Fe0 based on the contemporary knowledge on the mechanism of contaminant
removal by Fe0 and a mathematical model. It is showed that due to limitations
of the mass transfer of nano-Fe0 to contaminants, available concepts cannot
explain the success of nano-Fe0 injection for in situ groundwater remediation.
It is recommended to test the possibility of introducing nano-Fe0 to initiate
the formation of roll-fronts which propagation would induce the reductive
transformation of both dissolved and adsorbed contaminants. Within a
roll-front, FeII from nano-Fe0 is the reducing agent for contaminants. FeII is
recycled by biotic or abiotic FeIII reduction. While the roll-front concept
could explain the success of already implemented reaction zones, more research
is needed for a science-based recommendation of nano- Fe0 for subsurface
treatment by roll-front
Chromatin and epigenetics: current biophysical views
Recent advances in high-throughput sequencing experiments and their theoretical descriptions have determined fast dynamics of the "chromatin and epigenetics" field, with new concepts appearing at high rate. This field includes but is not limited to the study of DNA-protein-RNA interactions, chromatin packing properties at different scales, regulation of gene expression and protein trafficking in the cell nucleus, binding site search in the crowded chromatin environment and modulation of physical interactions by covalent chemical modifications of the binding partners. The current special issue does not pretend for the full coverage of the field, but it rather aims to capture its development and provide a snapshot of the most recent concepts and approaches. Eighteen open-access articles comprising this issue provide a delicate balance between current theoretical and experimental biophysical approaches to uncover chromatin structure and understand epigenetic regulation, allowing free flow of new ideas and preliminary results
Prediction of the success of cardiac resuscitation: a pattern classification approach based on ECG spectral and temporal features
Translocation and rearrangement of c-myc into immunoglobulin alpha heavy chain locus in primary cells from acute lymphocytic leukemia.
We report the molecular analysis of an 8;14 reciprocal chromosome translocation in a case of acute lymphocytic leukemia (L3 type). DNA from primary leukemic cells was analyzed on the basis of restriction endonuclease mapping by hybridization with various human c-myc and Ig heavy chain probes. The breakpoint of the translocation is within an approximately equal to 200-base-pair region in the first intron of the c-myc gene. The first, untranslated exon thereby remains on chromosome 8q-, whereas the whole protein-coding region is rearranged in the C alpha 1 locus on chromosome 14q+. RNA transfer blot analysis showed high levels of at least two different c-myc transcripts originated from the translocated gene. Both differ in size from the normal 2.2- and 2.4-kilobase transcripts. Both c-myc structure and expression were apparently normalized in remission phase. These studies demonstrate rearrangement and abnormal expression of c-myc in primary cells from an acute leukemia patient, thus adding to the concept of a key role for c-onc in human oncogenesis
Simulation par irradiation aux ions des dégùts d'irradiation dans le combustible nucléaire usé en situation de stockage géologique : Apport des études par DRX
International audienceDans un scĂ©nario de stockage Ă sec du combustible usĂ© en couche gĂ©ologiques profondes, le comportement de lâHe, produit par dĂ©croissance α des radionuclĂ©ides crĂ©Ă©s lors de lâirradiation en rĂ©acteur, doit ĂȘtre Ă©tudiĂ©. Un programme CEA-EDF a Ă©tĂ© dĂ©veloppĂ© dans les annĂ©es 2000, aboutissant Ă la dĂ©finition dâun modĂšle opĂ©rationnel. Une problĂ©matique reste cependant Ă investiguer, celle de la stabilitĂ© mĂ©canique du combustible et notamment de ses joints de grains sur de trĂšs longues durĂ©es de stockage
Characterization and Mathematical Modeling of Chloride Diffusion in Lagos Coastal Waters
Degradação de revestimentos de argamassa com finos de resĂduos de concreto por ciclos tĂ©rmicos
Este trabalho avalia propriedades de revestimentos de argamassa com finos de concreto submetidos a envelhecimento acelerado com ciclos tĂ©rmicos, utilizando-se um mĂ©todo de ensaio baseado na NBR 15575-4 (ABNT, 2013). As argamassas foram produzidas no traço 1:1:6 em volume (cimento, cal e areia) utilizando-se cimento CP II F-32, cal CH-I em pasta, areia de rio e finos produzidos a partir de agregado reciclado de concreto, adicionado nos teores de 2%; 4,5%; 7% e 9,5% em relação Ă massa da areia. Os revestimentos foram aplicados sobre substrato de cerĂąmica vermelha e avaliados, aos 28 dias de idade, a partir da resistĂȘncia de aderĂȘncia e forma de ruptura (NBR 13528 (ABNT, 2010)), da dureza superficial determinada por durĂŽmetro Shore tipo D (ASTM D 2240-5 (AMERICAN..., 2005)) e da velocidade de propagação de ondas ultrassĂŽnicas. ApĂłs, os sistemas formados pelo revestimento de argamassa aplicado sobre o substrato cerĂąmico foram submetidos a envelhecimento acelerado por exposição Ă ciclagem tĂ©rmica, o que degradou os revestimentos. Todos os revestimentos apresentaram queda de dureza superficial (na ordem de 10%), diminuição da velocidade de propagação de ondas ultrassĂŽnicas (na ordem de 25%) e queda de resistĂȘncia dos valores mĂ©dios de aderĂȘncia, na ordem de 15%. A forma de ruptura observada nos ensaios de resistĂȘncia de aderĂȘncia foi fortemente alterada em função do envelhecimento, sendo possĂvel constatar que os revestimentos com 2% e 4,5% de finos apresentaram maior degradação