While network formation is prevalent in nature, networks are generally not expected in inorganic structures. Exceptions are those cases in which surface states become important, such as nanoparticles. However, even in these cases, the morphology of these networks is difficult to control and they show a large degree of disorder. In this work, we show that highly ordered and interconnected nanoscale networks of functional metal oxides can be fabricated by a combination of polymer imprinting and polymer templating through solution processable methods. We report the fabrication of a number of functional oxide networks (i.e., BiFeO3, SrTiO3, La0.7Ca0.3MnO3, and HfO2) from solution, showing that all the oxide materials tried so far are able to follow the self-assembled network morphology dictated by the polymer structure. These networks were characterized for the overall structure by scanning electron microscopy and atomic force microscopy (AFM). Grazing incidence small angle X-ray scattering showed a good imprint quality on the mm2 scale for the combined networks, which is challenging given that multiple processing steps were involved during the fabrication. The material stoichiometries were investigated by X-ray photoemission spectroscopy and the crystal phases by grazing incidence wide angle X-ray scattering. When electronic functionality is anticipated, the networks behave as expected: conducting AFM on the La0.7Ca0.3MnO3 networks confirmed the conductive character of this composition; and piezoresponse force microscopy of the BiFeO3 network is consistent with the presence of ferroelectric behavior. These nanoscale networks show promise for future applications in adaptable electronics, such as neuromorphic computing or brain-inspired information processing.
Introduction: Hartmann's procedure (HP) consists of sigmoidectomy, rectal stump closure, and terminal colostomy. It was originally designed for and performed only in case of neoplastic obstructions. However, over time, indications have expanded and nowadays include complicated diverticulitis, traumatic colonic lesions, volvulus, and perforated rectosigmoid tumors. So there have been a growing number of patients undergoing HP, especially due to the increasing prevalence of sigmoid diverticular disease in the general population. Potentially, all these patients are waiting for their continuity to be restored. The original aim of this procedure was to reduce mortality due to anastomotic dehiscence in an emergent operation for neoplastic obstruction. However, reestablishing continuity after Hartmann's procedure (Hartmann's reversal [HR]) is considered a major surgical procedure and carries serious risk of both morbidity and mortality, ranging from 5% to 50%.1,2 This surely explains why a large proportion of patients undergoing HP will not have their bowel continuity restored. Spreading of laparoscopic expertise along with the documented advantages of minimally invasive approach (decreased postoperative pain, morbidity, hospital stay, and faster return to daily activities) in colonic surgery have lead to its application to procedures, such as HR. Since the first report of laparoscopic HR (LHR), there have been a growing number of publications in the world literature.3–19 This video shows the technique of laparoscopic restoration of bowel continuity after HP. Surgical Technique: The first step of the technique involves mobilization of the colostomy site. This is excised at the mucocutaneous junction circumferentially, until the peritoneum is entered. The edge of the stoma is revised to take away excessive scar tissue. An appropriately sized anvil of a circular stapler is then inserted into the colonic lumen and secured with a purse-string reabsorbable suture. The colostomy site is now used as port site for the establishment of pneumoperitoneum and a trocar or a hand-assist device can be placed for the camera. Three operative trocars are used: a 12-mm trocar in the right lower quadrant, a 10-mm in the right upper quadrant, and a 10-mm in the umbilicus. With the patient in the steep reverse Trendelenburg position, the rectal stump is identified. This step can be facilitated by a suture thread placed at the first surgery (Hartmann) or by transanally inserting a circular stapler, Hegar, dilators, or a rigid sigmoidoscope at HR. Lysis of adhesions is performed with sharp scissor dissection and minimal use of electric current to prevent any injury to the bowel. It is also important to minimize the risk of vascular injury during pelvic dissection, in a subsequent step of the procedure. In case the rectal stump is too long and includes a few folding of the distal sigmoid colon, the latter can be excised using a linear stapler and the specimen brought out through the colostomy site where the hand-assist device can been placed. Subsequently, with the patient in the Trendelenburg position, mobilization of the left colon proximal to the colostomy and take down of the splenic flexure is accomplished, by freeing the lateral attachments, to ensure a tension-free anastomosis with the rectal stump. An end-to-end colorectal anastomosis is created with an appropriately sized endoluminal circular stapler, possibly avoiding a stapler with diameter less than 28–29 mm. The pelvic cavity is filled with the saline solution and the air leak test is done by insufflating the air in the rectum while visualizing the anastomosis. The stoma wound is left partially open. Results: During the 8-year study period, 20 patients underwent laparoscopic HR. The median age was 65.4 years. Ten patients (50%) had undergone surgery for perforated diverticulitis, 3 (15%) for cancer, 7 (35%) for other reasons (volvulus, post-traumatic perforation, sigmoid perforation from foreign body). Previous HP had been performed laparoscopically in only three patients. The median operative time was 162.5 minutes. All the procedures were completed laparoscopically. The intraoperative complication rate was nil. Postoperative mortality and morbidity were 0% and 10%, respectively (one pneumonia, one bowel obstruction from postanastomotic stenosis, which required resection and re-do of the anastomosis). The median time to first flatus was 3 days, to normal diet 5 days. The median hospital stay was 9 days without readmissions. We followed-up the patients for a median of 44 months: when asked, all 20 (100%) said they would undergo the operation (LHR) again; 3 (15%) had been re-operated of laparoscopic mesh repair for incisional hernia. Conclusions: When performed by experienced surgeons, LHR is a feasible, safe, and reproducible operation, which allows early return of bowel function, early discharge, and fast return to work for the patient. It has a low morbidity rate. Drs. Valentino Fiscon, Giuseppe Portale, Antonio Mazzeo, Giovanni Migliorini and Flavio Frigo have no conflicts of interest or financial ties to disclose. Runtime of video: 5 mins 30 secs
Poly(phenylene sulfide benzimidazole) has been synthesized and tested as a potential material for high-temperature proton transport. A high content of sulfide bonds has been implemented in the polymer chains to endow a high antioxidant capacity and, in combination with bulky benzimidazole pendant units, to significantly suppress crystallinity and thereby improve the solubility in highly polar aprotic solvents. The amorphous polymer has high thermal stability and high glass transition temperature (Tg). Freestanding, insoluble, and robust membranes were obtained via thermal cross-linking of the benzimidazole moieties with octa-glycidyl polyhedral oligomeric silsesquioxane (g-POSS). The series of hybrid networks (cPPSBi_X, with X being the g-POSS content wt %) showed excellent oxidative stability, with cPPSBi_15 having weight loss lower than 5% after 264 h in Fenton's reagent at 80 °C. Elastic moduli as high as 868 MPa with reduced strain at break (1.8%) were obtained. After doping the membranes with phosphoric acid, proton conductivity in the range of 2.3 × 10–2 S cm–1 at 180 °C was obtained, and the membranes show a stress at break of 2.3 MPa. Dimensional and mechanical stability were maintained also at high doping levels thanks to the inclusion of g-POSS which provides the resulting hybrid networks with increased free volume and high cross-link density.
The solution processing of graphene typically requires the dissociation and suspension of nanosheets, leading to a reduction in nanocomposite performance. In article number 1900738, Maria Crespo, Emiliano Bilotti, Julien E. Gautrot, and co-workers propose photo-responsive polymer brushes to control the solution stability of graphene dispersions, whilst enabling on-demand deprotection of graphene nanomaterials and recovery of electronic and mechanical properties.
The droplet-like morphology, typical for many polymer-small-organic-molecule blends processed by spin coating, is quantitatively analyzed by gracing incidence small angle X-ray scattering by Giuseppe Portale and co-workers in article number 1702516. Using a combination of simultaneous X-ray scattering, laser scattering, and laser interferometry measurements, a formation mechanism based on liquid-liquid demixing followed by solvent partitioning is observed during spin coating.
Self-organized wrinkled templates are homogeneously fabricated over a large area (cm2) glass substrates by defocused ion beam irradiation, demonstrating the capability to induce and modify at will the out-of-plane tilt of the nanofacets with selected slope. We identify a region of morphological instability which leads to faceting for incidence angles of the ion beam with respect to the surface, θ, in the range 15° ≤ θ ≤ 45°, while for normal incidence, θ = 0°, and for grazing incidence at about 55–60° a flat morphology is achieved. The crucial parameter which controls the slope of the sawtooth profile is the local ion beam incidence angle on the facets which corresponds to the maximum erosion velocity. For θ = 30°, improved lateral order of the templates is found which can be exploited for the anisotropic confinement of functional layers. Here, we highlight the crucial role of the 1D nanopatterned template in driving the anisotropic crystallization of spun-cast conductive polymer thin films in registry with the faceted nanogrooves. In response, anisotropic electrical transport properties of the nanopatterned film are achieved with overall improvement higher than 60% with respect to a flat reference, thus showing the potential of such transparent large-area templates in nanoelectronics, optoelectronics, and biosensing.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)