Electromechanical Properties of Smart Vitrimers Reinforced with Carbon Nanotubes for SHM Applications.

The Structural Health Monitoring (SHM) capabilities of a well-studied self-healing epoxy resin based on disulfide bonds, through the addition of carbon nanotubes (CNTs), are studied. Since these materials demonstrated, in recent works, a high dependency of the dynamic hardener content on the repair performance, this study aimed to analyze the effect of the vitrimeric chemistry on the electromechanical properties by studying different 2-aminophenyl disulfide (2-AFD) hardener and CNT contents. The electrical conductivity increases with both the CNT and AFD contents, in general. Moreover, an excess of AFD close to the stoichiometric ratio with a low CNT content improved the tensile strength by 45%, while higher AFD contents promoted its detriment by 41% due to a reduced crosslinking density. However, no significant difference in the mechanical properties was observed at a higher CNT content, regardless of the AFD ratio. The developed materials demonstrate a robust electromechanical response at quasi-static conditions. The sensitivity significantly increases at higher AFD ratios, from 0.69 to 2.22 for the 0.2 wt.%. CNT system, which is advantageous due to the enhanced repair performance of these vitrimeric materials with a higher hardener content. These results reveal the potential use of self-healing vitrimers as integrated SHM systems capable of detecting damages and self-repairing autonomously.

Physiological differences and changes in global DNA methylation levels in Agave angustifolia Haw. albino variant somaclones during the micropropagation process.

KEY MESSAGE: Global DNA methylation changes caused by in vitro conditions are associated with the subculturing and phenotypic variation in Agave angustifolia Haw. While the relationship between the development of albinism and in vitro culture is well documented, the role of epigenetic processes in this development leaves some important questions unanswered. During the micropropagation of Agave angustifolia Haw., we found three different phenotypes, green (G), variegated (V) and albino (A). To understand the physiological and epigenetic differences among the somaclones, we analyzed several morphophysiological parameters and changes in the DNA methylation patterns in the three phenotypes during their in vitro development. We found that under in vitro conditions, the V plantlets maintained their CAM photosynthetic capacity, while the A variant showed no pigments and lost its CAM photosynthetic ability. Epigenetic analysis revealed that global DNA methylation increased in the G phenotype during the first two subcultures. However, after that time, DNA methylation levels declined. This hypomethylation correlated with the appearance of V shoots in the G plantlets. A similar correlation occurred in the V phenotype, where an increase of 2 % in the global DNA methylation levels was correlated with the generation of A shoots in the V plantlets. This suggests that an "epigenetic stress memory" during in vitro conditions causes a chromatin shift that favors the generation of variegated and albino shoots.

Nonconvulsive status epilepticus in adults: electroclinical differences between proper and comatose forms.

OBJECTIVE: Nonconvulsive status epilepticus (NCSE) represents an important percentage of status epilepticus in adults, but detailed studies of both NCSE proper and comatose NCSE are lacking. We retrospectively analyzed a prospectively collected series of 50 adult patients with a diagnosis of NCSE whose electroencephalograms (EEGs) have been interpreted for a period of 10 years by the same investigator. METHODS: Two groups, NCSE proper and comatose NCSE were considered. All clinical, EEGs, neuroimaging data, antiepileptic treatment and outcome were analyzed. RESULTS: Thirty-two patients (64%) had NCSE proper and 18 patients (36%) comatose NCSE. The mean age was 56 years (range 19-89 years). Fourteen (44%) were diagnosed with absence status epilepticus (ASE), one had simple partial status epilepticus (SPSE) and 17 (53%) had complex partial status epilepticus (CPSE). The mean episode duration (33.2±13.9 versus 60.6±34.0), mean number of antiepileptic drugs (AEDs) (1.46±0.5 versus 2.77±1.39) and neuroimaging anomalies (50% versus 16%) was significantly greater in the partial/focal NCSE proper subgroup than in the ASE subgroup. The mean age (56.0±19.9 versus 69.4±12.1), number of elderly individuals (46% versus 77%), mean duration of the episode (49.1±30.4 versus 153.3±142.6), mortality rate (6% versus 61%) and admission at ICU (18% versus 83%) was significantly higher in the comatose NCSE group than in the NCSE proper group (p<.05). Conversely, a previous history of chronic epilepsy was significantly more frequent (62% versus 5.6%) in the NCSE proper group. The mean duration of comatose NCSE was significantly greater in the surviving subgroup (102.5±29.1 versus 233.1±65.3; p<.05). CONCLUSIONS: Our study demonstrates that there are sufficient differences regarding age of onset, history of previous epilepsy, episode duration, mortality rate and clinical presentation between NCSE proper and comatose NCSE to recommend adoption in clinical practice. These results should be taken into account when developing future classifications and therapeutic trials on NCSE. SIGNIFICANCE: A distinction between NCSE proper (ambulatory forms of NCSE) and comatose NCSE is useful in the clinical practice and, therefore, it should taken in account in the design of future investigations on this heterogeneous epileptic condition.

Cardiac contusion following blunt chest trauma.

Cardiac contusion following blunt chest trauma is not rare, and the works in the literature report incidence rates between 5 and 50%. Traffic accidents are the most frequent cause of cardiac contusion followed by violent fall impacts, aggressions and the practice of risky sports. The spectrum of post-traumatic cardiac lesions varies greatly, ranging from no symptoms to decrease in cardiac function. Cardiogenic shock is a rarely encountered manifestation of blunt cardiac contusion. We review our experience of cardiac contusion after blunt chest trauma, and we describe two very severe cases that manifested as cardiogenic shock. We emphasize an early diagnosis by continuous electrocardiographic monitoring, serial electrocardiograms, echocardiography, serum determination of biochemical cardiac markers, radionuclide imaging and coronary angiography. The treatment includes continuous monitoring of cardiac rhythm, use of inotropic drugs, insertion of a catheter in the pulmonary artery for continuous assessment of cardiac output and, in extreme cases, the insertion of a contrapulsation balloon to maintain haemodynamics until improvement of cardiac function.

Gastric rupture from blunt abdominal trauma.

Gastric rupture following blunt abdominal trauma is rare, with a reported incidence of 0.02-1.7%. Road traffic accidents remain the most frequent cause. The factors most often implicated in the genesis of this entity are: a history of a recent meal, trauma to the left side of the body and an inappropriate use of seat belts. Splenic injury is generally the most common associated injury. The high morbidity and mortality are directly related to the number of associated injuries, delays in diagnosis and the development of intraabdominal sepsis. We performed a retrospective study of 1300 patients with blunt trauma to the abdomen from 1973 to 2001. Seven patients sustained a gastric rupture (five men and two women). The following associated characteristics were analysed: mechanism of injury, clinical presentation, possible associated injuries and postoperative complications, diagnosis methods and surgical treatment. We found an incidence of gastric rupture of 0.5%. We emphasise an early diagnosis and aggressive surgical treatment as a key to decreasing the mortality and morbidity from this injury. However, in our series, the morbidity is mainly from associated injuries.

Usefulness of venous oxygen saturation in the jugular bulb for the diagnosis of brain death: report of 118 patients.

OBJECTIVE: To assess the usefulness of venous oxygen saturation in the jugular bulb (SjO(2)) as a complementary test for the diagnosis of brain death. DESIGN: Prospective observational study. SETTING: Polytrauma intensive care unit (ICU) of an acute-care teaching hospital in Santander, Spain. PATIENTS: We studied 118 (44%) out of 270 patients with severe head injury and intracranial hemorrhage meeting criteria of brain death (lack of cardiac response to atropine, unresponsive apnea, and iso-electric EEG in the absence of shock, hypotension and treatment with muscle relaxants and/or central nervous system (CNS) depressant drugs). MEASUREMENTS AND RESULTS: At the moment at which clinical diagnosis of brain death was made and an iso-electric EEG was obtained, simultaneous oxygen saturation in central venous blood (right atrium) (SvO(2)) and jugular venous bulb (SjO(2)) samples was measured. The ratio between SvO(2) and SjO(2), expressed as CvjO(2) (the so-called central venous-jugular bulb oxygen saturation rate; CvjO(2) = SvO(2)/SjO(2)) was calculated. CvjO(2) less than 1 was obtained in 114 patients [mean (SD): 0.89 (0.02)], whereas CvjO(2) greater than 1 was obtained in only 4 (3.38%). In the group of 152 survivors, a single patient was discharged from the ICU in a vegetative state in which CvjO(2) was below 1. CvjO(2)as a complementary test for the diagnosis of brain death showed 96.6% sensitivity, 99.3% specificity, and 99.1% and 97.4% positive and negative predictive values, respectively. CONCLUSION: Central venous-jugular bulb oxygen saturation rate below 1 together with accepted clinical criteria (unresponsive coma with brainstem areflexia) provides non-invasive assessment of cerebral circulatory arrest that can help to suspect brain death.