The dynamics of strong laser-driven shocks in cluster media

Shocks and blast waves are ubiquitous features observed in plasma physics and in astrophysical phenomena and, as such, have long been the subject of experimental and theoretical studies. This thesis describes experimental and numerical investigations of the dynamics of laser driven shocks in cluster media. Target gases of atomic clusters have been shown to exhibit e cient absorption of high-intensity laser radiation, allowing to use `table-top' scale laser systems to drive high Mach-number shock waves. By applying hydrodynamic scaling laws, these systems can provide insight into the physics governing much larger astrophysical phenomena, such as supernova remnants. Experiments were conducted to investigate the structure and propagation dynamics of cylindrical blast waves in radiative and non-radiative gases. Shock pro ling studies performed at Imperial College London are presented, that highlight the need for non-LTE calculations of the shock physics. Investigations into the onset of the radiation driven thermal cooling instability (TCI) were performed by means of a streaked Schlieren technique, developed to obtain single-shot shock trajectory measurements, while removing any ambiguities imposed by shot-to-shot uctuations. In order to scale previous results to higher drive energies, experiments were performed using the Vulcan laser facility at the Rutherford Appleton Laboratory. The resulting cluster absorption and shocked gas comparison data is discussed in detail, including data indicating the rst experimental observation of TCI. To study shock collisions, a unique focal geometry has been employed, creating two near-parallel cylindrical shocks. By means of an interferometric tomography technique, the full 3D electron density pro le was reconstructed, showing complex material transport and Mach stem formation at the oblique shock collision interface, con rmed by 3D hydrodynamics simulations. To investigate this feature further, shock interactions with an obstruction were also performed, showing interesting propagation features through density steps imposed by the obstruction in the cold gas stream

Perioperative and Oncological Outcome of Laparoscopic Resection of Gastrointestinal Stromal Tumour (GIST) of the Stomach

Background. Surgery remains the only curative treatment for gastrointestinal stromal tumour (GIST). Resection needs to ensure tumour-free margins while lymphadenectomy is not required. Thus, partial gastric resection is the treatment of choice for small gastric GISTs. Evidence on whether performing resection laparoscopically compromises outcome is limited. Methods. We compiled patients undergoing laparoscopic resection of suspected gastric GIST between 2003 and 2007. Follow-up was performed to obtain information on tumour recurrence. Results. Laparoscopic resection with free margins was performed in 21/22 patients. Histology confirmed GIST in 17 cases, 4 tumours were benign neoplasms. Median operation time and postoperative stay for GIST patients were 130 (range 80–201) mins and 7 (range 5–95) days. Two patients experienced stapler line leakage necessitating surgical revision. After median follow-up of 18 (range 1–53) months, no recurrence occurred. Conclusions. Laparoscopic resection of gastric GISTs yields good perioperative outcomes. Oncologic outcome needs to be assessed with longer follow-up. For posterior lesions, special precaution is needed. Laparoscopic resection could become standard for circumscribed gastric GISTs if necessary precautions for oncological procedures are observed

Stromal regulatory T-cells are associated with a favourable prognosis in gastric cancer of the cardia

<p>Abstract</p> <p>Background</p> <p>Recent evidence suggests that CD4⁺CD25⁺FoxP3⁺regulatory T-cells (Treg) may be responsible for the failure of host anti-tumour immunity by suppressing cytotoxic T- cells. We assessed the prognostic significance of tumour infiltrating lymphocytes (TIL) in intestinal-type gastric cardiac cancer.</p> <p>Methods</p> <p>Tumour infiltrating lymphocyte (TIL) subsets and tumour infiltrating macrophages (TIM) were investigated in 52 cases using tissue microarrays. The interrelationship between the cell populations (CD3+, CD8+, CD20+, CD68+, GranzymeB+, FoxP3+) in different compartments and NED-survival was investigated (median follow-up time: 61 months).</p> <p>Results</p> <p>Intraepithelial infiltration with TIL and TIM including Treg was generally low and not related to NED-survival. However, patients with large numbers of FoxP3⁺Treg in the tumour stroma (>125.9 FoxP3⁺TILs/mm²) had a median survival time of 58 months while those with low FoxP3⁺TIL counts (<125.9 FoxP3⁺TILs/mm²) had a median survival time of 32 months (p = 0.006). Patients with high versus low stromal CD68⁺/FoxP3⁺cell ratios in primary tumour displayed median survivals of 32 and 55 months, respectively (p = 0.008).</p> <p>Conclusion</p> <p>Our results suggest that inflammatory processes within the tumour stroma of gastric intestinal-type adenocarcinomas located at the gastric cardia may affect outcome in two ways. Tumour-infiltrating macrophages are likely to promote carcinogenesis while large numbers of Treg are associated with improved outcome probably by inhibiting local inflammatory processes promoting carcinogenesis. Thus, inhibition of Treg may not be a feasible treatment option in gastric adenocarcinoma.</p

Sarcoma classification by DNA methylation profiling

Sarcomas are malignant soft tissue and bone tumours affecting adults, adolescents and children. They represent a morphologically heterogeneous class of tumours and some entities lack defining histopathological features. Therefore, the diagnosis of sarcomas is burdened with a high inter-observer variability and misclassification rate. Here, we demonstrate classification of soft tissue and bone tumours using a machine learning classifier algorithm based on array-generated DNA methylation data. This sarcoma classifier is trained using a dataset of 1077 methylation profiles from comprehensively pre-characterized cases comprising 62 tumour methylation classes constituting a broad range of soft tissue and bone sarcoma subtypes across the entire age spectrum. The performance is validated in a cohort of 428 sarcomatous tumours, of which 322 cases were classified by the sarcoma classifier. Our results demonstrate the potential of the DNA methylation-based sarcoma classification for research and future diagnostic applications

Studies of intense laser driven cluster explosions

Recent studies of the explosions of atomic clusters driven by high intensity femtosecond laser pulses have shown that at a sufficiently high intensity and fast laser rise time, the clusters can be stripped of all the electrons. The subsequent explosion is caused by the mutual Coulomb repulsion of the remaining ions. Assuming that the sudden inner cluster ionization approximation (SICI) is applicable, at the temporal onset of the Coulomb explosion all of the relevant electrons are already removed from their host atoms and become unbound electrons. Consequently the ions start from near their initial equilibrium positions in the cluster and expand isotropically. This simple model has been widely applied and has been successful in describing the ion energies observed from the explosions of small clusters (< 1000 atoms) with low charge states (like hydrogen and deuterium). Based on a theory developed by Breizman and Arefiev, if ion and electron motion are not separable, a dependence of the resulting ion energies to the laser polarization should occur. This is caused by a lowered average charge along the laser polarization due to electron motion in the external electric field. This thesis shows experimental results observing this effect. Furthermore Last and Jortner recently have proposed, based on particle dynamics simulations that heteronuclear clusters, with a mixture of heavy and light ions under certain conditions will not explode by the simple, equilibrium Coulomb explosion model but that dynamic effects can lead to a boosting of energy of the lighter ejected ions. In this thesis the experimental confirmation of this theoretically predicted ion energy enhancement in methane clusters is presented.Physic

The dynamics of strong laser-driven shocks in cluster media

Shocks and blast waves are ubiquitous features observed in plasma physics and in astrophysical phenomena and, as such, have long been the subject of experimental and theoretical studies. This thesis describes experimental and numerical investigations of the dynamics of laser driven shocks in cluster media. Target gases of atomic clusters have been shown to exhibit e cient absorption of high-intensity laser radiation, allowing to use `table-top' scale laser systems to drive high Mach-number shock waves. By applying hydrodynamic scaling laws, these systems can provide insight into the physics governing much larger astrophysical phenomena, such as supernova remnants. Experiments were conducted to investigate the structure and propagation dynamics of cylindrical blast waves in radiative and non-radiative gases. Shock pro ling studies performed at Imperial College London are presented, that highlight the need for non-LTE calculations of the shock physics. Investigations into the onset of the radiation driven thermal cooling instability (TCI) were performed by means of a streaked Schlieren technique, developed to obtain single-shot shock trajectory measurements, while removing any ambiguities imposed by shot-to-shot uctuations. In order to scale previous results to higher drive energies, experiments were performed using the Vulcan laser facility at the Rutherford Appleton Laboratory. The resulting cluster absorption and shocked gas comparison data is discussed in detail, including data indicating the rst experimental observation of TCI. To study shock collisions, a unique focal geometry has been employed, creating two near-parallel cylindrical shocks. By means of an interferometric tomography technique, the full 3D electron density pro le was reconstructed, showing complex material transport and Mach stem formation at the oblique shock collision interface, con rmed by 3D hydrodynamics simulations. To investigate this feature further, shock interactions with an obstruction were also performed, showing interesting propagation features through density steps imposed by the obstruction in the cold gas stream.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Reactivity studies on [Cp ` Fe(mu-I)](2): nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation

bibtex: ISI:000400553000098 bibtex\location:'THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND',publisher:'ROYAL SOC CHEMISTRY',type:'Article',affiliation:'Walter, MD (Reprint Author), Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. Maron, L (Reprint Author), Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. Reiners, Matthias; Maekawa, Miyuki; Daniliuc, Constantin G.; Freytag, Matthias; Jones, Peter G.; Walter, Marc D., Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. White, Peter S., Univ N Carolina, Dept Chem, CB 3290, Chapel Hill, NC 27599 USA. Hohenberger, Johannes; Sutter, Joerg; Meyer, Karsten, Univ Erlangen Nurnberg, Dept Chem & Pharm, Inorgan Chem, Egerlandstr 1, D-91058 Erlangen, Germany. Maron, Laurent, Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET8MH',eissn:'2041-6539','funding-acknowledgement':'Alexander von Humboldt Foundation; NSF [CHE-0615704]; Emmy Noether and Heisenberg program [WA 2513/2, WA 2513/6]; Humboldt Foundation','funding-text':'We thank the Alexander von Humboldt Foundation for a Feodor-Lynen Fellowship (M. D. W.) and Prof. Maurice Brookhart for providing financial support (through NSF Grant CHE-0615704) and laboratory facilities (M. D. W.) during the initial phase of this research program. Deutsche Forschungsgemeinschaft (DFG) is acknowledged for generous funding by the Emmy Noether and Heisenberg program (WA 2513/2 and WA 2513/6, respectively). LM is grateful to the Humboldt Foundation for a grant of experienced researcher and the Chinese Academy of Science. CalMip is also gratefully acknowledged for a generous computational grant.','journal-iso':'Chem. Sci.','keywords-plus':'FE2O2 DIAMOND CORE; STRUCTURAL-CHARACTERIZATION; DINITROGEN ACTIVATION; SULFUR CLUSTERS; SOLVENT PURIFICATION; MOLECULAR-STRUCTURES; ELECTRON-TRANSFER; 2FE-2S CLUSTERS; DOUBLE-BOND; FE-IVN','number-of-cited-references':'106',oa:'DOAJ Gold','orcid-numbers':'Meyer, Karsten/0000-0002-7844-2998 Daniliuc, Constantin G./0000-0002-6709-3673','research-areas':'Chemistry','researcherid-numbers':'Meyer, Karsten/G-2570-2012 Walter, Marc/E-4479-2012','times-cited':'4','unique-id':'ISI:000400553000098','usage-count-last-180-days':'4','usage-count-since-2013':'20','web-of-science-categories':'Chemistry, Multidisciplinary'\The iron half-sandwich [Cp'Fe(mu-I)](2) (Cp' = 1,2,4-(Me3C)(3)C5H2, 1) reacts with the pseudohalides NCO-, SCN-, SeCN- and N-3(-) to give [Cp'Fe(mu-NCO)](2) (2), [Cp'Fe(mu-S)](2) (3), [Cp'Fe(mu-Se-2)](2) (4) and [Cp'Fe(mu-N)](2) (5), respectively. Various spectroscopic techniques including X-ray diffraction, solid-state magnetic susceptibility studies and Fe-57 Mossbauer spectroscopy were employed in the characterization of these species. Mossbauer spectroscopy shows a decreasing isomer shift with increasing formal oxidation state, ranging from Fe(II) to Fe(IV), in complexes 1 to 5. The sulfido-bridged dimer 3 exhibits strong antiferromagnetic coupling between the Fe(III) centers. This leads to temperature-independent paramagnetism (TIP) at low temperature, from which the energy gap between the ground and the excited state can be estimated to be 2J = ca. 700 cm(-1). The iron(IV) nitrido complex [Cp'Fe(mu-N)](2) (5) shows no reactivity towards H-2 (10 atm), but undergoes clean reactions with CO (5 bar) and XylNC (Xyl = 2,6-Me2C6H3) to form the diamagnetic isocyanate and carbodiimide complexes [Cp'Fe(CO)(2)(NCO)] (7) and [Cp'Fe(CNXyl)(2)(NCNXyl)] (8), respectively. All compounds were fully characterized, and density functional theory (DFT) computations provide useful insights into their formation and the electronic structures of complexes 3 and 5