Shear-driven solidification of dilute colloidal suspensions

We show that the shear-induced solidification of dilute charge-stabilized (DLVO) colloids is due to the interplay between the shear-induced formation and breakage of large non-Brownian clusters. While their size is limited by breakage, their number density increases with the shearing-time. Upon flow cessation, the dense packing of clusters interconnects into a rigid state by means of grainy bonds, each involving a large number of primary colloidal bonds. The emerging picture of shear-driven solidification in dilute colloidal suspensions combines the gelation of Brownian systems with the jamming of athermal systems

Shear-induced reaction-limited aggregation kinetics of Brownian particles at arbitrary concentrations

The aggregation of interacting Brownian particles in sheared concentrated suspensions is an important issue in colloid and soft matter science per se. Also, it serves as a model to understand biochemical reactions occurring in vivo where both crowding and shear play an important role. We present an effective medium approach within the Smoluchowski equation with shear which allows one to calculate the encounter kinetics through a potential barrier under shear at arbitrary colloid concentrations. Experiments on a model colloidal system in simple shear flow support the validity of the model in the range considered. By generalizing Kramers' rate theory to the presence of collective hydrodynamics, our model explains the significant increase in the shear-induced reaction-limited aggregation kinetics upon increasing the colloid concentration

Shared Molecular Mechanisms among Alzheimer’s Disease, Neurovascular Unit Dysfunction and Vascular Risk Factors: A Narrative Review

Alzheimer’s disease (AD) is the most common type of dementia, affecting 24 million individuals. Clinical and epidemiological studies have found several links between vascular risk factors (VRF), neurovascular unit dysfunction (NVUd), blood-brain barrier breakdown (BBBb) and AD onset and progression in adulthood, suggesting a pathogenetic continuum between AD and vascular dementia. Shared pathways between AD, VRF, and NVUd/BBB have also been found at the molecular level, underlining the strength of this association. The present paper reviewed the literature describing commonly shared molecular pathways between adult-onset AD, VRF, and NVUd/BBBb. Current evidence suggests that VRF and NVUd/BBBb are involved in AD neurovascular and neurodegenerative pathology and share several molecular pathways. This is strongly supportive of the hypothesis that the presence of VRF can at least facilitate AD onset and progression through several mechanisms, including NVUd/BBBb. Moreover, vascular disease and several comorbidities may have a cumulative effect on VRF and worsen the clinical manifestations of AD. Early detection and correction of VRF and vascular disease by improving NVUd/BBBd could be a potential target to reduce the overall incidence and delay cognitive impairment in AD

Ultrafast extreme rejuvenation of metallic glasses by shock compression

Structural rejuvenation of glasses not only provides fundamental insights into their complicated dynamics but also extends their practical applications. However, it is formidably challenging to rejuvenate a glass on very short time scales. Here, we present the first experimental evidence that a specially designed shock compression technique can rapidly rejuvenate metallic glasses to extremely high-enthalpy states within a very short time scale of about 365 \ub1 8 ns. By controlling the shock stress amplitude, the shock-induced rejuvenation is successfully frozen at different degrees. The underlying structural disordering is quantitatively characterized by the anomalous boson heat capacity peak of glasses. A Deborah number, defined as a competition of time scales between the net structural disordering and the applied loading, is introduced to explain the observed ultrafast rejuvenation phenomena of metallic glasses

NORMALIZING EFFECT OF GAMMA-LINOLENIC ACID ON ETRETINATE-INDUCED HYPERTRIGLY- CERIDEMIA IN PSORIATIC PATIENTS: PRELIMINARY RESULTS

_________________ Synopsis Retinoids are a group of. synthesis compounds having vitamin A as their precursor. Among retino i d s, etretin ate i s commonly used, al o n e or in combi n ati o n with PUVA (8-methoxypsoralen+UYA), for diffuse and resistant psoriasis. However, eretrinate may induce locai (severe ski n dryness, flaking, cheilitis and fiss ures) and systemic side-effects. Among the systemic side-effects of etretinate, increased triglycerides, VLDLs, and cholesterol are freq ue ntly detected, whic h may cause treatment discontinuation. In the present paper 41 psoriatic patients undergoing Re-PUVA (Etretinate+PUVA) were considered. One month after the beginning of the therapy, 27 of them were additionally treated with gamma-linolenic acid, because of the dryness and itch induced by etretinate. During Re-PUVA treatment 11 out of these 27 patients showed increased triglyceride and cholesterol levels. A 2 month-treatment with gamma-linolenic acid induced an improvement of the cutaneous side-effects of eretrinate. Moreover, a statisticall y significant decrease of triglyceridemia (p<O.O I) and cholestero lemia (p<O.O I ) was detected followi ng the treatment with gamma-linolenic acid. These results demonstrate that association of gamma-linolenic acid is useful in contolling dyslipidemia if Re-PUVA treatment has to be continued to achieve clearing of psoriasis. ------------------Riassunto I retinoidi sono una famiglia di composti di sintesi che hanno il loro precursore nella Yit. A. I più diffusi in ambito terapeutico dermatologico sono l'etretinato, l'isotretinoina e l'acitretina. Questi farmaci agiscono promuovendo la differenziazione cheratinocitaria ed esercitano un effetto immunomodulatore. In particolare, l'etretinato trova indicazione, da solo o in associazione con PUVA-terapia (8-metossipsoralene+UYA), nel trattamento delle forme più estese e resistenti di psoriasi. L'etretinato, tuttavia, può indutTe effetti collaterali sia locali (secchezza cutanea marcata, desquamazione, cheilite e ragadi) che generali. Tra gl i effetti sistemici collaterali c he l'etretrinato può indun-e si ri leva più frequentemente un innalzamento dei trigliceridi, delle VLDL e del colesterolo che possono indun-e a sospendere la terapia prima del conseguimento di una risposta clinica soddisfacente. Nel presente lavoro vengono riportati i dati relativi al contollo dell' iperlipemia indotta da etretinato me- 107 Norma/1zmg effect of gamma-linolenic acid on etretinate-finduced hypertriglyceridemia in. .. diante l'impiego di acido gamma-linolenico per via generale. Tale acido grasso essenziale è stato impiegato in epoca recente per il controllo del prurito e della secchezza cutanea nei soggetti affetti da dermatite atopica; per questo motivo abbiamo ritenuto di utilizzarl o (480 mg/os/die) in un gruppo di 27 pazienti ps oriasici che, in cor so di tra ttame nto co n Etretinato (Etretinato 0,5 mg/Kg/os/die)+PUVA (Re-PUVA), avevano manifestato marcata secchezza cutanea e prurito, imputabili al retinoide. Ad un mese dall'inizio della terapia, 11 dei 27 pazienti affetti da secchezza cutanea e prurito avevano presentato anche anomalie del quadro lipidico, imputabili al trattamento con etretinato. II trattamento con acido gamma-linolenico per 2 mesi, o ltre a determ inare un miglioramento degli effetti collaterali cutanei, ha indotto anche una ridu zione statisticamente significativa della trigl iceridemia (p<0,01) e della colesterolemi a (p<0,0 1). Pertanto anche se gli innalzamenti di colesterolo e trigliceridi nella nostra casistica sono risultati, durante al terapia con etretinato, di moderata entità, l'util izzo d i acido gamma-linolenico ci ha permesso di continuare la terapia Re-PUVA con una certa sicurezza per il paziente. Come noto, infa tti , la popolazione psoriasica risu lta esposta ad un aumentato rischio di accidenti cardiovascolari, in associazione a diabete ed obesità, e l'ipertrig liceridemia iatrogena costituirebbe quindi un ulteriore fattore di ri schio

Prokaryotic abundance and heterotrophic metabolism in the deep Mediterranean Sea

A synthesis of field data carried out in the Mediterranean Sea are presented, aimed at contributing to the knowledge of three prokaryotic-mediated processes and their implications on the Carbon cycle. The distribution of exoenzymatic activities, secondary production and respiration rates was studied together with the prokaryotic abundances. Particular attention was paid to the meso- and bathypelagic layers which play an important role in the Mediterranean carbon cycle. The study is noteworthy because of its large spatial scale spanning the entire Mediterranean Sea over 4 years. In addition, two Atlantic stations in front of the Gibraltar Strait were investigated. The longitudinal distribution of prokaryotic activities and abundance along the MED showed different trends along the depthlayers. In particular, higher exoenzymatic rates were detected in the Eastern basin compared to the Western one; carbon respiration rate showed patterns variable with the sampling periods in the epipelagic and bathypelagic layers, while a consistent Westwards decreasing trend at the mesopelagic layers occurred. Specific enzyme activities per cell showed high values in the deepest layers for leucine aminopeptidase. Comparison with Carbon respiration rate data collected before the 2000s showed changing patterns of microbial heterotrophic processes in the Mediterranean Sea

Impact of atrial fibrillation in critically ill patients admitted to a stepdown unit

Background: Limited data are available on the clinical course of patients with history of atrial fibrillation (AF) when admitted in an intensive care environment. We aimed to describe the occurrence of major adverse events in AF patients admitted to a stepdown care unit (SDU) and to analyse clinical factors associated with outcomes, impact of dicumarolic oral anticoagulant (OAC) therapy impact and performance of clinical risk scores in this setting. Materials and methods: Single-centre, observational retrospective analysis on a population of subjects with AF history admitted to a SDU. Therapeutic failure (composite of transfer to ICU or death) was considered the main study outcome. Occurrence of stroke and major bleeding (MH) was considered as secondary outcomes. The performance of clinical risk scores was evaluated. Results: A total of 1430 consecutive patients were enrolled. 194 (13.6%) reported the main outcome. Using multivariate logistic regression, age (odds ratio [OR]: 1.03, 95% confidence interval [CI]: 1.01-1.05), acute coronary syndrome (OR:3.10, 95% CI: 1.88-5.12), cardiogenic shock (OR:10.06, 95% CI: 5.37-18.84), septic shock (OR:5.19,95%CI:3.29-18.84), acute respiratory failure (OR:2.49, 95% CI: 1.67-3.64) and OAC use (OR: 1.61, 95% CI: 1.02-2.55) were independently associated with main outcome. OAC prescription was associated with stroke risk reduction and to both MH and main outcome risk increase. CHA2 DS2 -VASc (c-index: 0.545, P = .117 for stroke) and HAS-BLED (c-index:0.503, P = .900 for MH) did not significantly predict events occurrence. Conclusions: In critically ill AF patients admitted to a SDU, adverse outcomes are highly prevalent. OAC use is associated to an increased risk of therapeutic failure, clinical scores seem unhelpful in predicting stroke and MH, suggesting a highly individualized approach in AF management in this setting