Actuation at micro- and nanoscale often requires large displacements and applied forces. The high work energy density that lies inside many phase transitions is an appealing feature for developing ...new actuating schemes, especially if the transition is reversible and scalable into small actuating domains. Here, we show the fabrication of a planar nanomechanical actuator having chevron-type geometry and based on the phase transition of VO2. This device is thermally activated through heating just above room temperature to trigger the VO2 crystalline symmetry change associated with the metal–insulator transition. The large lattice expansion of VO2 phase transition, compared to standard materials, is further amplified by the chevron-type geometry. DC and AC operation of the device are discussed.
Two‐terminal multistate memory elements based on VO2/TiO2 thin film microcantilevers are reported. Volatile and non‐volatile multiple resistance states are programmed by current pulses at ...temperatures within the hysteretic region of the metal‐insulator transition of VO2. The memory mechanism is based on current‐induced creation of metallic clusters by self‐heating of micrometric suspended regions and resistive reading via percolation.
Background
Duodenal gastrointestinal stromal tumors (D-GISTs) represent a rare entity.
1
Surgery is the primary treatment choice for localized or potentially resectable D-GISTs. The main principle is ...the complete excision of the lesion with microscopically negative margins, without performing lymph node dissection.
2
Nevertheless, the best surgical choice is still controversial since the strategy depends not only on the tumor size but also on its anatomic location.
3
,
4
As a result, surgical management ranges from a major resection such as pancreaticoduodenectomy to more conservative procedures.
5
–
8
This video presents a duodenal sparing robotic resection of a large GIST of the second-third duodenal portion.
Methods
A 49-year-old healthy female complained episodes of melena. Endoscopy with endoscopic ultrasound identified a 6-cm lesion of the second-third portion of the duodenum with recent bleeding, arising from muscolaris propria. A computed tomography scan confirmed a large mass suspected to be a GIST without metastases or involvement of the ampulla of Vater. On the basis of these findings, after a multidisciplinary consultation, she was offered robotic surgery with a radical intent.
Results
A duodenal-sparing da Vinci
®
Si™ resection with robot-sewn primary duodenal closure was performed. After an uneventful postoperative course, the patient was discharged on post-operative day 7. Final pathology revealed a high-grade risk D-GIST with free margins: adjuvant Imatinib was recommended.
9
At 4 years follow-up, no recurrence has been detected.
Conclusions
A robotic approach might be considered in cases of large D-GISTs amenable to a conservative R0 surgery. This system provides several technical advantages that facilitate otherwise complex resection and reconstruction.
10
Purpose
The aim of the study was to compare the clinical outcomes and histological findings in prompt and delayed appendectomy for acute appendicitis.
Methods
All patients who underwent appendectomy ...for histologically confirmed acute appendicitis from 2003 to 2009 were included in this study. Patients were divided into three groups according to the time of surgery after hospital admission: The early appendectomy (EA) group underwent surgery within 12 h, the early-delayed appendectomy (EDA) group between 12 and 24 h and the delayed appendectomy (DA) group more than 24 h. The perioperative data and pathological state of the appendix were evaluated and compared.
Results
A total of 723 patients, with histologically confirmed acute appendicitis, were included in the study: There were 518 patients in the EA group, 140 patients in the EDA group and 65 patients in the DA group. The operative times were similar in each group. Postoperative complications occurred in 49 patients (6.8 %) and were significantly higher in the DA group in comparison to the EA group (
p
= 0.0012) and EDA group (
p
= 0.003). Two patients (3 %) in the DA group died. There were no differences in the length of the hospital stay. The gangrenous appendicitis rate was significantly higher in the DA group (
p
<
0.05
) in comparison to the EA and EDA groups.
Conclusions
Performing appendectomy within 24 h from presentation does not increase the length of hospital stay or rate of complications. However, delayed appendectomy after 24 h from onset increases the rate of complications.
Various papers have introduced the use of positron emission tomography (PET) with
GaGa-radiolabeled fibroblast-activation protein inhibitor (FAPi) radiopharmaceuticals in different subtypes of ...gastric cancer (GC). Our aim was to assess the diagnostic performance of this novel molecular imaging technique in GC with a systematic review and meta-analysis. A straightforward literature search of papers concerning the diagnostic performance of FAP-targeted PET imaging was performed. Original articles evaluating this novel molecular imaging examination in both newly diagnosed GC patients and GC patients with disease relapse were included. The systematic review included nine original studies, and eight of them were also eligible for meta-analysis. The quantitative synthesis provided pooled detection rates of 95% and 97% for the assessment of primary tumor and distant metastases, respectively, and a pooled sensitivity and specificity of 74% and 89%, respectively, for regional lymph node metastases. Significant statistical heterogeneity among the included studies was found only in the analysis of the primary tumor detection rate (I
= 64%). Conclusions: Beyond the limitations of this systematic review and meta-analysis (i.e., all the included studies were conducted in Asia, and using
FFDG PET/CT as a comparator of the index test), the quantitative data provided demonstrate the promising diagnostic performance of FAP-targeted PET imaging in GC. Nevertheless, more prospective multicentric studies are needed to confirm the excellent performances of FAP-targeted PET in this cluster of patients.
Relaxation oscillators consist of periodic variations of a physical quantity triggered by a static excitation. They are a typical consequence of nonlinear dynamics and can be observed in a variety of ...systems. VO2 is a correlated oxide with a solid‐state phase transition above room temperature, where both electrical resistance and lattice parameters undergo a drastic change in a narrow temperature range. This strong nonlinear response allows to realize spontaneous electrical oscillations in the megahertz range under a DC voltage bias. These electrical oscillations are employed to set into mechanical resonance a microstructure without the need of any active electronics, with small power consumption and with the possibility to selectively excite specific flexural modes by tuning the value of the DC electrical bias in a range of few hundreds of millivolts. This actuation method is robust and flexible and can be implemented in a variety of autonomous DC‐powered devices.
High‐frequency mechanical actuation of a microelectromechanical system (MEMS) device from a DC electrical bias is achieved by employing VO2, a material exhibiting a combined electrical and structural phase transition at 65 °C. The DC bias triggers spontaneous and repetitive phase transitions on a micrometric region that works as an engine to power the movement of the MEMS around its mechanical resonances.
The incidence of periprosthetic joint infections (PJIs) is ~2% of total procedures and it is expected to rise due to an ageing population. Despite the large burden PJI has on both the individual and ...society, the immune response to the most commonly isolated pathogens, i.e.,
and
, remains incompletely understood. In this work, we integrate the analysis of synovial fluids from patients undergoing hip and knee replacement surgery with in-vitro experimental data obtained using a newly developed platform, mimicking the environment of periprosthetic implants. We found that the presence of an implant, even in patients undergoing aseptic revisions, is sufficient to induce an immune response, which is significantly different between septic and aseptic revisions. This difference is confirmed by the presence of pro- and anti-inflammatory cytokines in synovial fluids. Moreover, we discovered that the immune response is also dependent on the type of bacteria and the topography of the implant surface. While
seems to be able to hide better from the attack of the immune system when cultured on rough surfaces (indicative of uncemented prostheses),
reacts differently depending on the contact surface it is exposed to. The experiments we performed in-vitro also showed a higher biofilm formation on rough surfaces compared to flat ones for both species, suggesting that the topography of the implant could influence both biofilm formation and the consequent immune response.
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