Lattice sites of ion-implanted Li in diamond

Published in: Appl. Phys. Lett. 66 (1995) 2733-2735 citations recorded in [Science Citation Index] Abstract: Radioactive Li ions were implanted into natural IIa diamonds at temperatures between 100 K and 900 K. Emission channelling patterns of a-particles emitted in the nuclear decay of 8Li (t1/2 = 838 ms) were measured and, from a comparison with calculated emission channelling and blocking effects from Monte Carlo simulations, the lattice sites taken up by the Li ions were quantitatively determined. A fraction of 40(5)% of the implanted Li ions were found to be located on tetrahedral interstitial lattice sites, and 17(5)% on substitutional sites. The fractions of implanted Li on the two lattice sites showed no change with temperature, indicating that Li diffusion does not take place within the time window of our measurements.

Amorphization of ZnSe by ion implantation at low temperatures

Radioactive Cd and Se ions were implanted into high-resistivity ZnSe single crystals around 60 K and 300 K. Their lattice sites were determined by measuring the channelling and blocking effects of the emitted conversion electrons or positrons directly after implantation and after annealing at different temperatures up to 600 K. Implantation doses were in the range of 3$\times 10^{12}$ - 3$\times10^{13}$/cm$^2$. The experimental results of this emission channelling technique yield a high substitutional fraction of the implanted ions directly after implantation at room temperature. At 60 K the substitutional fraction of implanted ions is highly sensitive to the ion dose. Above a critical dose of around 1.4$\times10^{13}$ Cd/cm$^2$ or 2.1$\times10^{13}$ Se/cm$^2$ the substitutional fraction completely disappears indicating an amorphous surrounding of the probe atom. Damage recovery was observed below room temperature and at an annealing temperature around 500 K. A quantitative analysis of measured channelling yields will be given by comparison with calculated electron channelling profiles based on the dynamical theory of electron diffraction

α\alpha-emission channeling investigations of the lattice location of Li in Ge

The $\alpha$-emission channeling and blocking technique is a direct method for lattice site determination of radioactive atoms in single crystals. Position-sensitive detection of emitted $\alpha$ -particles provides an efficient means of carrying out such experiments at very low doses (10$^{10}$-10$^{11}$ implanted probe atoms per spectrum). Comparison of the experimental data to Monte Carlo simulations of complete two-dimensional channeling patterns (e.g. ±2°C around , and axes, which also includes all relevant planar directions) allows for straight-forward identification and rather accurate quantitative determination of occupied lattice sites, while at the same time the energy spectrum of emitted a particles gives information on the probe atom depth distribution. We illustrate this for the case of ion implanted $^8$Li (t_=0.8 s) in Ge, where we identify mainly tetrahedral Li at room temperature, and bond-centered Li at slightly elevated temperature

Understanding lactatemia in human sepsis potential impact for early management

Rationale: Hyperlactatemia in sepsis may derive from a prevalent impairment of oxygen supply/demand and/or oxygen use. Discriminating between these two mechanisms may be relevant for the early fluid resuscitation strategy. Objectives: To understand the relationship among central venous oxygen saturation (ScvO2), lactate, and base excess to better determine the origin of lactate. Methods: This was a post hoc analysis of baseline variables of 1,741 patients with sepsis enrolled in the multicenter trial ALBIOS (Albumin ItalianOutcome Sepsis). Variableswere analyzed as a function of sextiles of lactate concentration and sextiles of ScvO2.Wedefined the "alactic base excess," as the sum of lactate and standard base excess. Measurements and Main Results: Organ dysfunction severity scores, physiologic variables of hepatic, metabolic, cardiac, and renal function, and 90-day mortality were measured. ScvO2 was lower than 70% only in 35% of patients. Mortality, organ dysfunction scores, and lactate were highest in the first and sixth sextiles of ScvO2. Although lactate level related strongly to mortality, it was associated with acidemia only when kidney function was impaired (creatinine >2 mg/dl), as rapidly detected by a negative alactic base excess. In contrast, positive values of alactic base excess were associated with a relative reduction of fluid balance. Conclusions: Hyperlactatemia is powerfully correlated with severity of sepsis and, in established sepsis, is caused more frequently by impaired tissue oxygen use, rather than by impaired oxygen transport. Concomitant acidemia was only observed in the presence of renal dysfunction, as rapidly detected by alactic base excess. The current strategy of fluid resuscitation could be modified according to the origin of excess lactate

Research in Extracorporeal Life Support: A Call to Action

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Mechanisms of oxygenation responses to proning and recruitment in COVID-19 pneumonia

Purpose: This study aimed at investigating the mechanisms underlying the oxygenation response to proning and recruitment maneuvers in coronavirus disease 2019 (COVID-19) pneumonia. Methods: Twenty-five patients with COVID-19 pneumonia, at variable times since admission (from 1 to 3 weeks), underwent computed tomography (CT) lung scans, gas-exchange and lung-mechanics measurement in supine and prone positions at 5 cmH2O and during recruiting maneuver (supine, 35 cmH2O). Within the non-aerated tissue, we differentiated the atelectatic and consolidated tissue (recruitable and non-recruitable at 35 cmH2O of airway pressure). Positive/negative response to proning/recruitment was defined as increase/decrease of PaO2/FiO2. Apparent perfusion ratio was computed as venous admixture/non aerated tissue fraction. Results: The average values of venous admixture and PaO2/FiO2 ratio were similar in supine-5 and prone-5. However, the PaO2/FiO2 changes (increasing in 65% of the patients and decreasing in 35%, from supine to prone) correlated with the balance between resolution of dorsal atelectasis and formation of ventral atelectasis (p = 0.002). Dorsal consolidated tissue determined this balance, being inversely related with dorsal recruitment (p = 0.012). From supine-5 to supine-35, the apparent perfusion ratio increased from 1.38 ± 0.71 to 2.15 ± 1.15 (p = 0.004) while PaO2/FiO2 ratio increased in 52% and decreased in 48% of patients. Non-responders had consolidated tissue fraction of 0.27 ± 0.1 vs. 0.18 ± 0.1 in the responding cohort (p = 0.04). Consolidated tissue, PaCO2 and respiratory system elastance were higher in patients assessed late (all p < 0.05), suggesting, all together, “fibrotic-like” changes of the lung over time. Conclusion: The amount of consolidated tissue was higher in patients assessed during the third week and determined the oxygenation responses following pronation and recruitment maneuvers

Recombinant activated factor VII (Novo7®) in patients with ventricular assist devices: Case report and review of the current literature

Postoperative bleeding might become a serious problem in the management of cardiac surgical patients, with marked medical and economic impact. In these life-threatening situations, massive haemorrhage represents frequently a combination of surgical and coagulopathic bleeding. Surgical bleeding results from a definite source at the operation site and can be corrected using surgical standard techniques. Acute coagulopathies, in contrast, result from impaired thrombin formation, and require optimized therapeutical strategies. Effective pharmacological treatment will be complicated by the presence of ventricular assist devices (VAD), which necessarily imply effective anticoagulation

Prevention, diagnosis, therapy and follow-up care of sepsis: 1st revision of S-2k guidelines of the German Sepsis Society (Deutsche Sepsis-Gesellschaft e.V. (DSG)) and the German Interdisciplinary Association of Intensive Care and Emergency Medicine (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin (DIVI))

Practice guidelines are systematically developed statements and recommendations that assist the physicians and patients in making decisions about appropriate health care measures for specific clinical circumstances taking into account specific national health care structures. The 1st revision of the S-2k guideline of the German Sepsis Society in collaboration with 17 German medical scientific societies and one self-help group provides state-of-the-art information (results of controlled clinical trials and expert knowledge) on the effective and appropriate medical care (prevention, diagnosis, therapy and follow-up care) of critically ill patients with severe sepsis or septic shock. The guideline had been developed according to the “German Instrument for Methodological Guideline Appraisal” of the Association of the Scientific Medical Societies (AWMF). In view of the inevitable advancements in scientific knowledge and technical expertise, revisions, updates and amendments must be periodically initiated. The guideline recommendations may not be applied under all circumstances. It rests with the clinician to decide whether a certain recommendation should be adopted or not, taking into consideration the unique set of clinical facts presented in connection with each individual patient as well as the available resources