Resolving the Structural Debate for the Hydrated Excess Proton in Water

It has long been proposed that the hydrated excess proton in water (aka the solvated "hydronium" cation) likely has two limiting forms, that of the Eigen cation (H9O4+) and that of the Zundel cation (H5O2+). There has been debate over which of these two is the more dominant species and/or whether intermediate (or "distorted") structures between these two limits are the more realistic representation. Spectroscopy experiments have recently provided further results regarding the excess proton. These experiments show that the hydrated proton has an anisotropy reorientation time scale on the order of 1-2 ps. This time scale has been suggested to possibly contradict the picture of the more rapid "special pair dance" phenomenon for the hydrated excess proton, which is a signature of a distorted Eigen cation. The special pair dance was predicted from prior computational studies in which the hydrated central core hydronium structure continually switches (O–H···O)* special pair hydrogen-bond partners with the closest three water molecules, yielding on average a distorted Eigen cation with three equivalent and dynamically exchanging distortions. Through state-of-art simulations it is shown here that anisotropy reorientation time scales of the same magnitude are obtained that also include structural reorientations associated with the special pair dance, leading to a reinterpretation of the experimental results. These results and additional analyses point to a distorted and dynamic Eigen cation as the most prevalent hydrated proton species in aqueous acid solutions of dilute to moderate concentration, as opposed to a stabilized or a distorted (but not "dancing") Zundel cation

The Hopping Mechanism of the Hydrated Excess Proton and Its Contribution to Proton Diffusion in Water

In this work a series of analyses are performed on ab initio molecular dynamics (AIMD) simulations of a hydrated excess proton in water to quantify the relative occurrence of concerted hopping events and rattling events, and thus to further elucidate the hopping mechanism of proton transport in water. Contrary to results reported in certain earlier papers, the new analysis finds that concerted hopping events do occur in all simulations, but that the majority of events are the product of proton rattling, where the excess proton will rattle between two or more waters. The results are consistent with the proposed special-pair dance model of the hydrated excess proton, wherein the acceptor water molecule for the proton transfer will quickly change (resonate between three equivalent special pairs) until a decisive proton hop occurs. To remove the misleading effect of simple rattling, a filter was applied to the trajectory such that hopping events that were followed by back hops to the original water are not counted. A steep reduction in the number of multiple hopping events is found when the filter is applied, suggesting that many multiple hopping events that occur in the unfiltered trajectory are largely the product of rattling, contrary to prior suggestions. Comparing the continuous correlation function of the filtered and unfiltered trajectories, we find agreement with experimental values for the proton hopping time and Eigen-Zundel interconversion time, respectively.Comment: 31 pages, 11 figure

Patient Selection for Active Surveillance for Small Renal Masses: A Systematic Review of the Literature

BACKGROUND: The role of active surveillance (AS) has been recognized as a management strategy for localized small renal masses (SRMs). The EAU guidelines suggest AS can be offered to frail and/or comorbid patients diagnosed with SRM due to the low cancer-specific-mortality (CSM) and higher competing-cause mortality. As specific cut-offs defining the characteristics of frail and comorbid patients who may benefit from AS remain less clear, our objective is to conduct a systematic review aiming to identify potential characteristics that could assist physicians in shared decision-making. METHODS: The systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Two authors independently screened the literature according to the PICOs criteria previously outlined in our registered review protocol (via Pubmed, Embase, and the Cochrane Central Register of Controlled Trials), extracted data, and assessed the risk of bias, using Newcastle-Ottawa Scale. Studies that analyzed differences in patient's tumor-related and molecular characteristics associated with any differences in growth rate (GR), overall survival (OS), cancer-specific survival (CSS), and metastasis-free survival (MFS), were considered eligible. RESULTS: Nineteen studies comprising a total of 5105 patients were analyzed. Patient-specific factors such as age and cardiovascular index, which demonstrated a predominant impact on OS, exhibited a high degree of consistency across the analyzed studies. Less concordance was found when exploring GR, with the main predictors being ethnicity, age, sex, comorbidity, symptoms, and eGFR. The analysis of tumor-related characteristics, such as tumor size, nephrometry score, and mass histology, among others, yielded contradictory outcomes concerning their impact on GR and CSS. CONCLUSION: Age, cardiovascular index, and chronic kidney disease have shown to be reliable predictors of OS. Nonetheless, significant debates persist regarding tumor characteristics or molecular markers that may influence survival and GR. Further research is awaited to shed light on the potential to identify prognostic factors. This would aid in pinpointing the subgroup of patients who could experience additional benefits from AS, potentially leading to a reduced risk of progression. It is imperative to standardize approaches to AS and reporting of results, as this will be pivotal for future quantitative analyses

Endoscopic Tactile Capsule for Non-Polypoid Colorectal Tumour Detection

An endoscopic tactile robotic capsule, embedding miniaturized MEMS force sensors, is presented. The capsule is conceived to provide automatic palpation of non-polypoid colorectal tumours during colonoscopy, since it is characterized by high degree of dysplasia, higher invasiveness and lower detection rates with respect to polyps. A first test was performed employing a silicone phantom that embedded inclusions with variable hardness and curvature. A hardness-based classification was implemented, demonstrating detection robustness to curvature variation. By comparing a set of supervised classification algorithms, a weighted 3-nearest neighbor classifier was selected. A bias force normalization model was introduced in order to make different acquisition sets consistent. Parameters of this model were chosen through a particle swarm optimization method. Additionally, an ex-vivo test was performed to assess the capsule detection performance when magnetically-driven along a colonic tissue. Lumps were identified as voltage peaks with a prominence depending on the total magnetic force applied to the capsule. Accuracy of 94 % in hardness classification was achieved, while a 100 % accuracy is obtained for the lump detection within a tolerance of 5 mm from the central path described by the capsule. In real application scenario, we foresee our device aiding physicians to detect tumorous tissues

Single-port robotic partial nephrectomy: impact on perioperative outcomes and hospital stay

Single-port (SP) robotic surgery is a novel technology and is at the beginning of its adoption curve in urology. The goal of this narrative review is to provide an overview of SP-robotic partial nephrectomy (PN) 4 years after the introduction of the da Vinci SP dedicated platform, focusing on perioperative outcomes, length of stay, and surgical technique. A nonsystematic review of the literature was conducted. The research included the most updated articles that referred to SP robotic PN. Since its commercial release in 2018, several institutions have reproduced robotic PN by using the SP platform, both via a transperitoneal and a retroperitoneal approach. The published SP-robotic PN series are generally based on preliminary experiences by surgeons who had previous experience with conventional multi-arms robotic platforms. The reported outcomes are encouraging. Overall, three studies reported that SP-robotic PN cases had nonsignificantly different operative time, estimated blood loss, overall complications rate, and length of stay compared to the conventional ‘multi-arms’ robotic PN. However, in all these series, renal masses treated by SP had overall lower complexity. Moreover, two studies underlined decreased postoperative pain as a major pro of adopting the SP system. This should reduce/avoid the need for opioids after surgery. No study compared SP-robotic versus multi-arms robotic PN in cost-effectiveness. Published experience with SP-robotic PN has reported the feasibility and safety of the approach. Preliminary results are encouraging and at least noninferior with respect to those from the multi-arms series. Prospective comparative studies with long-term oncologic and functional results are awaited to draw more definitive conclusions and better establish the more appropriate indications of SP robotics in the field of PN

Diagnostic Biopsy for Small Renal Tumours: A Survey of Current European Practice

Background and objective: Renal tumour biopsy (RTB) can help in risk stratification of renal tumours with implications for management, but its utilisation varies. Our objective was to report current practice patterns, experiences, and perceptions of RTB and research gaps regarding RTB for small renal masses (SRMs). Methods: Two web-based surveys, one for health care providers (HCPs) and one for patients, were distributed via the European Association of Urology Young Academic Urologist Renal Cancer Working Group and the European Society of Residents in Urology in January 2023. Key findings and limitations: The HCP survey received 210 responses (response rate 51%) and the patient survey 54 responses (response rate 59%). A minority of HCPs offer RTB to >50% of patients (14%), while 48% offer it in <10% of cases. Most HCPs reported that RTB influences (61.5%) or sometimes influences (37.1%) management decisions. Patients were more likely to favour active treatment if RTB showed high-grade cancer and less likely to favour active treatment for benign histology. HCPs identified situations in which they would not favour RTB, such as cystic tumours and challenging anatomic locations. RTB availability (67%) and concerns about delays to treatment (43%) were barriers to offering RTB. Priority research gaps include a trial demonstrating that RTB leads to better clinical outcomes, and better evidence that benign/indolent tumours do not require active treatment. Conclusions and clinical implications: Utilisation of RTB for SRMs in Europe is low, even though both HCPs and patients reported that RTB results can affect disease management. Improving timely access to RTB and generating evidence on outcomes associated with RTB use are priorities for the kidney cancer community. Patient summary: A biopsy of a kidney mass can help patients and doctors make decisions on treatment, but our survey found that many patients in Europe are not offered this option. Better access to biopsy services is needed, as well as more research on what happens to patients after biopsy

INVESTIGATING THE SEISMIC RESPONSE OF URM WALLS WITH IRREGULAR OPENING LAYOUT THROUGH DIFFERENT MODELING APPROACHES

The façade and internal walls of unreinforced masonry (URM) buildings often present an irregular opening layout, due to architectural reasons or modifications to the structure, which make the expected seismic damage pattern less predictable a priori. Therefore, the discretization of the walls in structural components is not standardized, conversely to cases with a regular opening layout for which the available modeling methods are corroborated by seismic damage surveys reporting recurrent failure patterns. The structural component discretization is a relevant step for the code-conforming seismic assessment, typically based on comparing the internal forces and drifts of each component to strength criteria and drift thresholds. Therefore, the lack of well-established approaches can significantly influence the assessment. The issue is even more evident when the structural components must be identified a priori in the modeling stage, namely for equivalent frame models. The applicability of available methods for discretization of URM walls with irregular opening layout has been already investigated in literature, but a conclusive judgment requires further studies. In this context, this paper presents an overview of the preliminary results addressing the numerical modeling of this type of walls within the framework of the DPC-ReLUIS 2022-2024 project (Subtask 10.3), funded by the Italian Department of Civil Protection. The Subtask aims to propose consensus-based recommendations for researchers and practitioners which can contribute to harmonize the use of different modeling approaches. Seven research groups are involved in the research, adopting different modeling approaches and computer codes, but similar assumptions and the same analysis method (pushover) are used. The benchmark URM structure illustrated in the paper is a two-story wall from which four configurations with increasing irregularity of opening layout were derived. The results of four modeling approached are presented. Three of them reproduce the mechanical response of masonry at the material scale by means of FE models implemented in OpenSees, DIANA and Abaqus software, while the remaining approach describes the mechanical response of masonry at the macro-element scale in 3DMacro software. Results were compared in terms of capacity curves, predicted failure mechanisms and evolution of internal forces in piers. The adoption of consistent assumptions among the different approaches led to an overall agreement of predictions at both wall and pier scales, particularly in terms of damage pattern with higher concentration of damage at the ground story. Despite that, differences on the pushover curves have been highlighted. They are mainly due to some deviations of the internal forces in squat piers deriving from a complex load flow in these elements

Young star clusters in the Large Magellanic Cloud: NGC 1805 and NGC 1818

We present colour-magnitude diagrams for two rich (~10^4 Msun) Large Magellanic Cloud star clusters with ages ~10^7 years, constructed from optical and near-infrared data obtained with the Hubble Space Telescope. These data are part of an HST project to study LMC clusters with a range of ages. In this paper we investigate the massive star content of the young clusters, and determine the cluster ages and metallicities, paying particular attention to Be star and blue straggler populations and evidence of age spreads. We compare our data to detailed stellar population simulations to investigate the turn-off structure of ~25 Myr stellar systems, highlighting the complexity of the blue straggler phenomenon.Comment: 15 pages, accepted for publication in MNRAS, postscript version with higher quality figures available from http://www.ast.cam.ac.uk/~raj/biblio.htm

Application of Italian Guidelines for structural-foundational and seismic risk classification of bridges: The Fabre experience on a large bridge inventory

The recent issuance of Guidelines for the classification and management of risk, safety assessment, and monitoring of existing bridges has standardized the methodology for analyzing the safety and managing bridges at a national level. The Guidelines propose a multi-level analysis approach, where the assessment of structures is conducted with increasing levels of detail and complexity. This paper describes the work carried out by the Fabre Consortium, the Italian scientific alliance on risk assessment and monitoring of civil infrastructural systems, together with ANAS s.p.a.; one of the major Italian road authorities, for the implementation of the Italian Guidelines to a large bridge inventory distributed over the Italian territory. This paper is specifically devoted to structural-foundational and seismic risk classification. The results of the application of the methodology to a large database is presented together with statistical analyses on parameters determining hazard, vulnerability and exposure and with the definition of the most recurrent typological bridge classes within the bridge inventory