Thermo-temporal physisorption in metal-organic frameworks probed by cyclic thermo-ellipsometry

Temperature-induced sorption in porous materials is a well-known process. What is more challenging is to determine how the rate at which temperature is varied affects these processes. To address this question, we introduce a methodology called "cyclic thermo-ellipsometry" to explore the thermo-kinetics of vapor physisorption in metal-organic framework films.

Shaping 90 wt% NanoMOFs into Robust Multifunctional Aerogels Using Tailored Bio-Based Nanofibrils

Metal-organic frameworks (MOFs) are hybrid porous crystalline networks with tunable chemical and structural properties. However, their excellent potential is limited in practical applications by their hard-to-shape powder form, making it challenging to assemble MOFs into macroscopic composites with mechanical integrity. While a binder matrix enables hybrid materials, such materials have a limited MOF content and thus limited functionality. To overcome this challenge, nanoMOFs are combined with tailored same-charge high-aspect-ratio cellulose nanofibrils (CNFs) to manufacture robust, wet-stable, and multifunctional MOF-based aerogels with 90 wt% nanoMOF loading. The porous aerogel architectures show excellent potential for practical applications such as efficient water purification, CO₂ and CH₄ gas adsorption and separation, and fire-safe insulation. Moreover, a one-step carbonization process enables these aerogels as effective structural energy-storage electrodes. This work exhibits the unique ability of high-aspect-ratio CNFs to bind large amounts of nanoMOFs in structured materials with outstanding mechanical integrity-a quality that is preserved even after carbonization. The demonstrated process is simple and fully discloses the intrinsic potential of the nanoMOFs, resulting in synergetic properties not found in the components alone, thus paving the way for MOFs in macroscopic multifunctional composites.

Metal-Organic Framework Photonic Balls: Single Object Analysis for Local Thermal Probing

Due to their high porosity and chemical versatility, metal-organic frameworks (MOFs) exhibit physical properties appealing for photonic-based applications. While several MOF photonic structures have been reported, examples of applications thereof are mainly limited to chemical sensing. Herein, the range of application of photonic MOFs is extended to local thermal and photothermal sensing by integrating them into a new architecture: MOF photonic balls. Micrometric-sized photonic balls are made of monodispersed MOFs colloids that are self-assembled via spray-drying, a low-cost, green, and high-throughput method. The versatility of the process allows tuning the morphology and the composition of photonic balls made of several MOFs and composites with tailored optical properties. X-ray nanotomography and environmental hyperspectral microscopy enable analysis of single objects and their evolution in controlled atmosphere and temperature. Notably, in presence of vapors, the MOF photonic balls act as local, label-free temperature probes. Importantly, compared to other thermal probes, the temperature detection range of these materials can be adjusted "on-demand." As proof of concept, the photonic balls are used to determine local temperature profiles around a concentrated laser beam. More broadly, this work is expected to stimulate new research on the physical properties of photonic MOFs providing new possibilities for device fabrication.

Colloidal metal-organic framework particles: the pioneering case of ZIF-8

The production of metal-organic frameworks (MOFs) in the form of colloids has brought a paradigm shift in the design of new functional porous materials. Along with their intrinsic interest as porous solids, and contrary to their bulk powder counterparts, colloidal MOF particles can additionally be dispersed, shaped, functionalized, transformed and assembled in a controlled manner, conferring them further properties and applications. In this regard, zeolitic imidazolate framework-8 (ZIF-8) has become a pioneering MOF constituent of colloidal science. Today, the understanding of the role of synthetic parameters, learned after one decade of research, enables the production of monodisperse colloidal ZIF-8 particles with tunable dimensions and morphologies, offering the opportunity to develop new functional materials and composites with novel and promising functionalities. This tutorial review provides a useful guide to prepare ZIF-8 in its colloidal form, covering the published studies on the synthesis of homogeneous ZIF-8 particles with controlled size and shape. In addition, we present the most relevant advances in the development of colloidal ZIF-8 hybrid single-particles, reflecting the great potential and rapid development of this interdisciplinary research field. Finally, we highlight how formulation of ZIF-8 as colloids has led to the emergence of novel physicochemical phenomena that are useful for practical applications. This review aims at promoting the development of MOFs as colloids, taking ZIF-8 as a pioneering and successful case that clearly shows the benefits of bridging MOF chemistry and colloidal science.

Template-Free, Surfactant-Mediated Orientation of Self-Assembled Supercrystals of Metal-Organic Framework Particles

Mesoscale self-assembly of particles into supercrystals is important for the design of functional materials such as photonic and plasmonic crystals. However, while much progress has been made in self-assembling supercrystals adopting diverse lattices and using different types of particles, controlling their growth orientation on surfaces has received limited success. Most of the latter orientation control has been achieved via templating methods in which lithographic processes are used to form a patterned surface that acts as a template for particle assembly. Herein, a template-free method to self-assemble (111)-, (100)-, and (110)-oriented face-centered cubic supercrystals of the metal-organic framework ZIF-8 particles by adjusting the amount of surfactant (cetyltrimethylammonium bromide) used is described. It is shown that these supercrystals behave as photonic crystals whose properties depend on their growth orientation. This control on the orientation of the supercrystals dictates the orientation of the composing porous particles that might ultimately facilitate pore orientation on surfaces for designing membranes and sensors.

Sequential Deconstruction-Reconstruction of Metal-Organic Frameworks: An Alternative Strategy for Synthesizing (Multi)-Layered ZIF Composites

Here, we report the synthesis of (multi)-layered zeolitic imidazolate framework (ZIF-8/-67) composite particles via a sequential deconstruction-reconstruction process. We show that this process can be applied to construct ZIF-8-on-ZIF-67 composite particles whose cores are the initially etched particles. In addition, we demonstrate that introduction of functional inorganic nanoparticles (INPs) onto the crystal surface of etched particles does not disrupt ZIF particle reconstruction, opening new avenues for designing (multi)-layered ZIF-on-INP-on-ZIF composite particles comprising more than one class of inorganic nanoparticles. In these latter composites, the location of the inorganic nanoparticles inside each single metal-organic framework particle as well as of their separation at the nanoscale (20 nm) is controlled. Preliminary results show that (multi)-layered ZIF-on-INP-on-ZIF composite particles comprising a good sequence of inorganic nanoparticles can potentially catalyze cascade reactions.

Self-assembly of polyhedral metal-organic framework particles into three-dimensional ordered superstructures

Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals. Those superstructures feature a photonic bandgap that can be tuned by controlling the size of the ZIF-8 particles and is also responsive to the adsorption of guest substances in the micropores of the ZIF-8 particles. In addition, superstructures with different lattices can also be assembled by tuning the truncation of ZIF-8 particles, or by using octahedral UiO-66 MOF particles instead. These well-ordered, sub-micrometre-sized superstructures might ultimately facilitate the design of three-dimensional photonic materials for applications in sensing.

Comparison of protocols measuring diffusion and partition coefficients in the stratum corneum

Partition (K) and diffusion (D) coefficients are important to measure for the modelling of skin penetration of chemicals through the stratum corneum (SC). We compared the feasibility of three protocols for the testing of 50 chemicals in our main studies, using three cosmetics-relevant model chemicals with a wide range of logP values. Protocol 1: SC concentration-depth profile using tape-stripping (measures KSC/v and DSC /HSC2 , where HSC is the SC thickness); Protocol 2A: incubation of isolated SC with chemical (direct measurement of KSC/v only) and Protocol 2B: diffusion through isolated SC mounted on a Franz cell (measures KSC/v and DSC /HSC2 , and is based on Fick's laws). KSC/v values for caffeine and resorcinol using Protocol 1 and 2B were within 30% of each other, values using Protocol 2A were ~two-fold higher, and all values were within 10-fold of each other. Only indirect determination of KSC/v by Protocol 2B was different from the direct measurement of KSC/v by Protocol 2A and Protocol 1 for 7-EC. The variability of KSC/v for all three chemicals using Protocol 2B was higher compared to Protocol 1 and 2A. DSC /HSC2 values for the three chemicals were of the same order of magnitude using all three protocols. Additionally, using Protocol 1, there was very little difference between parameters measured in pig and human SC. In conclusion, KSC/v, and DSC values were comparable using different methods. Pig skin might be a good surrogate for human skin for the three chemicals tested. Copyright © 2017 The Authors Journal of Applied Toxicology published by John Wiley & Sons Ltd.

Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals

Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

The effects of using the Internet on the health-related quality of life in people with spinal cord injury: a controlled study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To compare the health-related quality of life (HRQoL) in people with spinal cord injury (SCI) who use the Internet versus those who don't and with a control group of able-bodied individuals. To investigate the frequency of Internet usage before and after injury. To evaluate the differences in terms of demographic features of both groups, analyze the variation in the Internet usage pattern of people with SCI before and after the injury.

SETTING

Istanbul, Turkey.

METHODS

A total of 60 people with SCI (38 Internet users, 22 nonusers) were included in the study. The control group consisted of 33 healthy persons of similar age and sex. The HRQoL was evaluated with the SF-36 Health Survey.

RESULTS

The scores of all the subscales of the SF-36, except vitality, were significantly lower in people with SCI than those of the controls'. The bodily pain subscale and physical component scores were found to be significantly higher in people with SCI using the Internet than the nonuser group with SCI (P<0.05). The Internet usage frequency increased significantly in people with SCI after injury (P<0.05). A significant correlation was found between time since injury and Internet use (r=0.365, P=0.007).

CONCLUSION

Although HRQoL scores were lower in people with an SCI, the physical status component score was better in the Internet user SCI group. As there is a significant increase in the time spent online after injury, the Internet could be an effective modality to contact and educate people with an SCI.

Methylation of the p16INK4A promoter is associated with malignant behavior in abdominal extra-adrenal paragangliomas but not pheochromocytomas

Pheochromocytomas and abdominal extra-adrenal paragangliomas are related to endocrine tumors of the sympathetic nervous system. Studies in animal models have shown that inactivation of the products of the cyclin dependent kinase inhibitor 2A (CDKN2A) gene locus, p16INK4A and p14ARF, promotes the development of pheochromocytoma, especially in malignant form. The present study evaluated the involvement of CDKN2A in human pheochromocytomas and abdominal extra-adrenal paragangliomas from 55 patients. Promoter methylation was assessed using quantitative Pyrosequencing and methylation-specific PCR, and mRNA expression was measured by quantitative real-time PCR. For p16, western blot analysis and sequencing were also performed. succinate dehydrogenase complex subunit B (SDHB) sequencing analysis included extra-adrenal paragangliomas, all tumors classified as malignant, and cases diagnosed at 30 years or younger. The p16INK4A promoter was heavily methylated in a subset of paragangliomas, and this was significantly associated with malignancy (P<0.0043) and SDHB mutation (P<0.002). p16INK4A mRNA expression showed moderate suppression in malignant cases (P<0.05). In contrast, very little p14ARF promoter methylation was seen and there was no significant difference in p14ARF expression between tumors and normal samples. The p16 protein expression was reduced in 16 tumors, and sequence variations were observed in four tumors including the missense mutation A57V and the single nucleotide polymorphism (SNP) A148T. The results suggest that p16INK4A, and not p14ARF, is a subject of frequent involvement in these tumors. Importantly, hypermethylation of the p16INK4A promoter was significantly associated with malignancy and metastasis, and SDHB gene mutations. This finding suggests an etiological link and could provide a clinical utility for diagnostic purposes.

Laparoscopic myotomy for oesophageal achalasia--adding an antireflux procedure is not always necessary

Laparoscopy is the access of choice for functional surgery of the gastroesophageal junction, and oesophagocardiomyotomy, as the conventional surgical treatment of achalasia, is one of the favourable indications for laparoscopic surgery. Laparoscopic anterior myotomy technique is highly effective and secure for relieving dysphagia with minimal risk of gastroesophageal reflux. Fifteen patients with the diagnosis of achalasia were treated with laparoscopic anterior face oesophagocardiomyotomy without a concomitant antireflux procedure. There was not any perioperative complication and no procedure was converted to open operation. Oesophageal cineradiography, manometry and 24-h pH monitoring were repeated postoperatively. Manometry showed a significant reduction of the resting tone (48-34.4 to 18-3.2 mmHg), and patients were free of symptoms for reflux and dysphagia at the follow-up between 8 and 96 (median 42) months. Only one patient needed pneumatic dilation, 1 year after the operation for mild dysphagia, and one patient had moderate reflux, which was managed by medication. Thanks to minimal invasive technique of laparoscopic surgery and intraoperative endoscopy, oesophagocardiomyotomy can safely be performed in a length needed without dividing lateral and posterior phrenoesophageal ligamentous attachments. Consequently, adding an antireflux procedure routinely is not necessary. We advocate laparoscopic anterior oesophagocardiomyotomy alone as the first-line treatment for achalasia.

Vagotomy without gastric drainage laparoscopic or thoracoscopic approach

BACKGROUND/AIMS

This article describes the surgical techniques and preliminary results of a prospective trial of videoendoscopic bilateral truncal vagotomy without a drainage procedure in a series of selected patients with chronic non-obstructive intractible duodenal ulcer.

METHODOLOGY

Video laparoscopic and videothoracoscopic truncal vagotomy of chronic duodenal ulcer in 32 patients has been successfully performed in the Department of Surgery, Istanbul Medical Faculty Hospital. These patients undergoing bilateral truncal vagotomy (BTV) without a drainage procedure were chosen with selective indication regarding the absence of pyloric obstruction and presence of hyperacidity. Endoscopic pyloric balloon dilatation (PBD) was performed at the same stage with vagotomy only for 20 patients as a prospective trial. The results of acid secretory tests and endoscopic control were studied.

RESULTS

All the patients tolerated pure truncal vagotomy well under strict follow-up with semiliquid diet and promotility medication started 24 hours after surgery. The mean decrease in secretory tests for basal acid output (BAO) and peak acid output (PAO) were 70.6% and 79.5%, respectively. Endoscopic controls, 2 months after the operation, showed healing ulcers in patients who were able to be followed-up. One patient who had partial pyloric stenosis and was operated by BTV and PBD, required a drainage procedure in spite of repeated pyloric dilatation. During the mean follow-up period of 26 months (range: 10-46), the only symptom was moderate diarrhea in 4 patients, which became well with medical treatment or spontaneously.

CONCLUSIONS

Videoendoscopic truncal vagotomy seems to be an alternative treatment regimen for the management of chronic duodenal ulcer in a group of selected patients, as a simple, surgeon independent and efficient procedure. Instead of routine addition of a drainage procedure after truncal vagotomy, which may improve the morbidity, observation of the patient after truncal vagotomy with dietary caution supplementary to prokinetic medication may be the chosen method in some patients.

Laparoscopic esophagomyotomy without an antireflux procedure for the treatment of achalasia

Various gastroenteric surgical procedures have been attempted laparoscopically. Laparoscopic esophagomyotomy (LE) with or without fundoplication, performed for achalasia, has gained popularity. In our clinic, LE (Heller's myotomy) was performed on six patients with achalasia. All patients underwent barium esophagography, endoscopy, and esophageal manometry for diagnosis. Extramucosal myotomy was started 6 cm above the cardioesophageal junction on the left anterolateral aspect of the esophagus and continued 1 cm below this area. Endoscopic control of the distal esophageal mucosa and the stomach was carried out under direct laparoscopic visualization following the completion of myotomy during the operation. LE was completed without complication in five patients. In one patient (16%), mucosal perforation occurred after myotomy during endoscopic control and was repaired with endostitches. There were no postoperative complications. The average hospital stay was 3 days. Three of the six patients agreed to 24-h pH monitoring, the results of which showed no evidence of reflux. All patients were completely symptom free in the postoperative period. The average preoperative lower esophageal sphincter pressure was 44 mm Hg, whereas in the early postoperative period and 6 months later, it was 11 mm Hg. There was no dysphagia or reflux esophagitis during the follow-up period (range 12 to 24 months). LE is associated with low morbidity and a high success rate, comparable with an open procedure, and can be done without an antireflux procedure.

Video endoscopic truncal vagotomies without gastric drainage

The authors report 32 patients with chronic duodenal ulcer treated by bilateral truncal vagotomy (BTV) performed via laparoscopy or thoracoscopy. All cases were resistant to medical treatment and chosen with selective indication regarding endoscopic/radiologic and laboratory examination for absence of pyloric obstruction and presence of hyperacidity. Only one patient had partial pyloric stenosis preoperatively due to chronic duodenal ulcer. No drainage procedure was used after BTV, and an endoscopic pyloric balloon dilatation (PBD) was performed at the same time as vagotomy for 20 cases; 12 patients were followed without dilatation as a prospective trial. Semiliquid diet and promotility medication were started 24 h after surgery. All patients tolerated pure truncal vagotomy without any problem, except for two patients: one in whom open drainage procedure was required and one in whom PBD was performed. Basal acid output and peak acid output were measured the day before and 1 week after the operation. A mean decrease of hyperacidity was found: 70.6% for basal and 79.5% for peak acid output. Four patients suffered from moderate symptoms of diarrhea occurring intermittently and responded to medical treatment or recovered spontaneously. Median hospital stay was 4.8 days (range 3-10 days). Endoscopic control performed for 28 patients 2 and 6 months after the operation showed healing of the ulcer. But the patient who had partial pyloric stenosis and was operated on with BTV and PBD required an open drainage procedure (Jaboulay gastrojejunostomy) in spite of repeated PBD. There was no other gastropyloric outlet obstruction in this preliminary study with mean follow-up of 22 months (range 6-42 months).

Mesh infections after laparoscopic inguinal hernia repair

Several complications like hematoma and seroma have been reported after laparoscopic inguinal hernia repair (LH). Sepsis due to infection of the patch is an uncommon complication. In this retrospective trial, we evaluated three male patients who developed postoperative mesh infection after LH by transabdominal preperitoneal patch (TAPP) technique in two institutions. Diagnosis was confirmed by clinical symptoms, signs, ultrasonography, and computerized tomography (CT), and definitive treatment was provided by removing the mesh. In the first case, mesh infection occurred 10 months after laparoscopic left inguinal hernia repair with TAPP for recurrence. The infection manifested itself as an external fistula at the drain site. The mesh was removed laparoscopically due to persistent suppuration. In the second case, mesh infection occurred 3 months after transabdominal preperitoneal hernia repair on the left. The patch was removed because of the persistent suppuration despite repetitive drainage and lavage. In the third case, mesh infection occurred in 15 days after transabdominal preperitoneal hernia repair on the right. External drainage was performed under CT guidance, but suppuration could not be stopped. Thus the mesh was removed. In three cases, infection could not be stopped after diagnosis despite drainage and antibiotic coverage, and then it was decided to remove the mesh. The meshes were removed under general anesthesia for the first two cases and under local anesthesia for the third one. During the follow-up period, no recurrences were noted. The mesh infections of these three cases, resistant to conservative treatment methods, completely disappeared after mesh removal.

Video thoracoscopic truncal vagotomies: technique and preliminary results

BACKGROUND/AIMS

This report presents the technique and preliminary results of a prospective trial of videothoracoscopic bilateral truncal vagotomy without a drainage procedure in a series of selected patients having elective surgery for chronic non obstructive duodenal ulcer.

MATERIAL AND METHODS

Videothoracoscopic truncal vagotomy was performed in six patients with chronic duodenal ulcer resistant to medical treatment. These patients undergoing neither a drainage nor a dilatation procedure supplementary to bilateral truncal vagotomy were chosen with selective indication regarding the absence of pyloric obstruction and presence of hyperacidity. The results of acid secretory tests and endoscopic control were studied.

RESULTS

A Videothoracoscopic approach to truncal vagotomy was performed simply with a mean operation time of 42 min (35-80) providing all the advantages of minimally invasive surgery such as low morbidity and early recovery. The mean decrease of peak acid output was 77.4% and the ulcer healed without any gastric stasis symptoms or signs as compared with the endoscopic controls at the second month postoperatively. During the mean follow-up period of 26 months (3-38), the only symptom was moderate diarrhea which resolved spontaneously.

CONCLUSION

Truncal vagotomy by videothoracoscopy as a simple, surgeon independent and efficient procedure seems to be an alternative treatment regimen for the management of chronic duodenal ulcer in a group of selected patients. Instead of routine addition of a drainage procedure after truncal vagotomy which may improve the morbidity, observation of the patient after truncal vagotomy with dietary caution supplementary to prokinetic medication may be the chosen method in today's circumstances.

The internal cavoatrial derivation for temporary vascular exclusion of the liver in the dog

Vascular exclusion of the liver by clamping the hepatic pedicle and inserting an internal cavoatrial shunt allows bloodless hepatic surgery to be performed. The internal cavoatrial shunt performed on 30 dogs was studied to define its optimal hemodynamic characteristics. The internal diameter should measure half the caliber of the inferior vena cava and the total surface of the holes allowing blood flow to the shunt must be three times the internal caliber of the shunt. The aortic clamping associated with the clamping of the hepatic pedicle and the insertion of the internal cavoatrial shunt considerably diminishes the arterial blood pressure variations resulting from the splanchnic stasis. Administration of methylprednisolone (30 mg/kg) at the beginning of the experiment also plays a role in preventing alterations in the small intestine.

[Esophago-jejunostomy at the level of the neck for restoration of continuity in carcinoma of the esophagus (after esophageal resection or for palliative reasons) (author's transl)]

A technic of esophago-jejunostomy in the neck is described which uses a Y loop, to which is given a further blood supply through the internal mammary vessels, united to the vessels of the transplanted loop through microsurgical anastomoses. This technic is used either for purely palliative reasons or when the esophageal tumour has become inoperable, or after esophagectomy as a procedure for reconstruction of the digestive tract.