Human history is largely characterized by the massive use of wood, the most well-known natural composite material, possessing unique thermal, mechanical, and environmental features that make it ...suitable for several applications, ranging from civil engineering, art, and household uses, to business uses (including furniture, stationery, shipbuilding, and fuel). Further, as a renewable and recyclable biomass, wood perfectly matches the current circular economy concept. However, because of its structure and composition, wood is not transparent: therefore, the possibility of removing the embedded lignin, hence limiting the light-scattering phenomena, has been investigated over the last ten to fifteen years, hence obtaining the so-called "transparent wood (TW)". This latter represents an up-to-date key material, as it can be utilized as obtained or further functionalized, combining the transparency with other features (such as flame retardance, energy storage ability, and environmental protection, among others), which widen the potential (and practical) applications of wood. The present manuscript aims at summarizing first the current methods employed for obtaining transparent wood, and then the latest achievements concerning the properties of transparent wood, providing the reader with some perspectives about its novel functionalizations and applications.
Main Recommendations
Prophylaxis
1
ESGE recommends routine rectal administration of 100 mg of diclofenac or indomethacin immediately before endoscopic retrograde cholangiopancreatography (ERCP) in ...all patients without contraindications to nonsteroidal anti-inflammatory drug administration.
Strong recommendation, moderate quality evidence.
2
ESGE recommends prophylactic pancreatic stenting in selected patients at high risk for post-ERCP pancreatitis (inadvertent guidewire insertion/opacification of the pancreatic duct, double-guidewire cannulation).
Strong recommendation, moderate quality evidence.
3
ESGE suggests against routine endoscopic biliary sphincterotomy before the insertion of a single plastic stent or an uncovered/partially covered self-expandable metal stent for relief of biliary obstruction.
Weak recommendation, moderate quality evidence.
4
ESGE recommends against the routine use of antibiotic prophylaxis before ERCP.
Strong recommendation, moderate quality evidence.
5
ESGE suggests antibiotic prophylaxis before ERCP in the case of anticipated incomplete biliary drainage, for severely immunocompromised patients, and when performing cholangioscopy.
Weak recommendation, moderate quality evidence.
6
ESGE suggests tests of coagulation are not routinely required prior to ERCP for patients who are not on anticoagulants and not jaundiced.
Weak recommendation, low quality evidence.
Treatment
7
ESGE suggests against salvage pancreatic stenting in patients with post-ERCP pancreatitis.
Weak recommendation, low quality evidence.
8
ESGE suggests temporary placement of a biliary fully covered self-expandable metal stent for post-sphincterotomy bleeding refractory to standard hemostatic modalities.
Weak recommendation, low quality evidence.
9
ESGE suggests to evaluate patients with post-ERCP cholangitis by abdominal ultrasonography or computed tomography (CT) scan and, in the absence of improvement with conservative therapy, to consider repeat ERCP. A bile sample should be collected for microbiological examination during repeat ERCP.
Weak recommendation, low quality evidence.
Polymer hydrogels are 3D networks consisting of hydrophilic crosslinked macromolecular chains, allowing them to swell and retain water. Since their invention in the 1960s, they have become an ...outstanding pillar in the design, development, and application of engineered polymer systems suitable for biomedical and pharmaceutical applications (such as drug or cell delivery, the regeneration of hard and soft tissues, wound healing, and bleeding prevention, among others). Despite several well-established synthetic routes for developing polymer hydrogels based on batch polymerization techniques, about fifteen years ago, researchers started to look for alternative methods involving simpler reaction paths, shorter reaction times, and lower energy consumption. In this context, frontal polymerization (FP) has undoubtedly become an alternative and efficient reaction model that allows for the conversion of monomers into polymers via a localized and propagating reaction—by means of exploiting the formation and propagation of a “hot” polymerization front—able to self-sustain and propagate throughout the monomeric mixture. Therefore, the present work aims to summarize the main research outcomes achieved during the last few years concerning the design, preparation, and application of FP-derived polymeric hydrogels, demonstrating the feasibility of this technique for the obtainment of functional 3D networks and providing the reader with some perspectives for the forthcoming years.
In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an ...alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with the material accounts for the creation of magnetic polarization effects (i.e., magnetic hysteresis losses) and/or eddy currents (i.e., Joule losses, upon the formation of closed electrical loops), which, in turn, cause the heating up of the material itself. The heat involved can be exploited for different uses, ranging from the curing of thermosetting systems, the welding of thermoplastics, and the processing of temperature-sensitive materials (through selective IH) up to the activation of special effects in polymer systems (such as self-healing and shape-memory effects). This review aims at summarizing the current state-of-the-art of IH processes for polymers, providing readers with the current limitations and challenges, and further discussing some possible developments for the following years.
Main Recommendations
ESGE recommends offering stone extraction to all patients with common bile duct stones, symptomatic or not, who are fit enough to tolerate the intervention.
Strong ...recommendation, low quality evidence.
ESGE recommends liver function tests and abdominal ultrasonography as the initial diagnostic steps for suspected common bile duct stones. Combining these tests defines the probability of having common bile duct stones.
Strong recommendation, moderate quality evidence.
ESGE recommends endoscopic ultrasonography or magnetic resonance cholangiopancreatography to diagnose common bile duct stones in patients with persistent clinical suspicion but insufficient evidence of stones on abdominal ultrasonography.
Strong recommendation, moderate quality evidence.
ESGE recommends the following timing for biliary drainage, preferably endoscopic, in patients with acute cholangitis, classified according to the 2018 revision of the Tokyo Guidelines:
– severe, as soon as possible and within 12 hours for patients with septic shock
– moderate, within 48 – 72 hours
– mild, elective.
Strong recommendation, low quality evidence.
ESGE recommends endoscopic placement of a temporary biliary plastic stent in patients with irretrievable biliary stones that warrant biliary drainage.
Strong recommendation, moderate quality of evidence.
ESGE recommends limited sphincterotomy combined with endoscopic papillary large-balloon dilation as the first-line approach to remove difficult common bile duct stones.
Strong recommendation, high quality evidence.
ESGE recommends the use of cholangioscopy-assisted intraluminal lithotripsy (electrohydraulic or laser) as an effective and safe treatment of difficult bile duct stones.
Strong recommendation, moderate quality evidence.
ESGE recommends performing a laparoscopic cholecystectomy within 2 weeks from ERCP for patients treated for choledocholithiasis to reduce the conversion rate and the risk of recurrent biliary events.
Strong recommendation, moderate quality evidence.
This Guideline is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE). It addresses the prophylaxis of post-endoscopic retrograde cholangiopancreatography (post-ERCP) ...pancreatitis.
Main recommendations
1
ESGE recommends routine rectal administration of 100 mg of diclofenac or indomethacin immediately before or after ERCP in all patients without contraindication. In addition to this, in the case of high risk for post-ERCP pancreatitis (PEP), the placement of a 5-Fr prophylactic pancreatic stent should be strongly considered. Sublingually administered glyceryl trinitrate or 250 µg somatostatin given in bolus injection might be considered as an option in high risk cases if nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated and if prophylactic pancreatic stenting is not possible or successful.
2
ESGE recommends keeping the number of cannulation attempts as low as possible.
3
ESGE suggests restricting the use of a pancreatic guidewire as a backup technique for biliary cannulation to cases with repeated inadvertent cannulation of the pancreatic duct; if this method is used, deep biliary cannulation should be attempted using a guidewire rather than the contrast-assisted method and a prophylactic pancreatic stent should be placed.
4
ESGE suggests that needle-knife fistulotomy should be the preferred precut technique in patients with a bile duct dilated down to the papilla. Conventional precut and transpancreatic sphincterotomy present similar success and complication rates; if conventional precut is selected and pancreatic cannulation is easily obtained, ESGE suggests attempting to place a small-diameter (3-Fr or 5-Fr) pancreatic stent to guide the cut and leaving the pancreatic stent in place at the end of ERCP for a minimum of 12 – 24 hours.
4
ESGE does not recommend endoscopic papillary balloon dilation as an alternative to sphincterotomy in routine ERCP, but it may be advantageous in selected patients; if this technique is used, the duration of dilation should be longer than 1 minute.
This Guideline is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE). It provides practical advice on how to achieve successful cannulation and sphincterotomy at ...minimum risk to the patient. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was adopted to define the strength of recommendations and the quality of evidence.
Main recommendations
1
ESGE suggests that difficult biliary cannulation is defined by the presence of one or more of the following: more than 5 contacts with the papilla whilst attempting to cannulate; more than 5 minutes spent attempting to cannulate following visualization of the papilla; more than one unintended pancreatic duct cannulation or opacification (low quality evidence, weak recommendation).
2
ESGE recommends the guidewire-assisted technique for primary biliary cannulation, since it reduces the risk of post-ERCP pancreatitis (moderate quality evidence, strong recommendation).
3
ESGE recommends using pancreatic guidewire (PGW)-assisted biliary cannulation in patients where biliary cannulation is difficult and repeated unintentional access to the main pancreatic duct occurs (moderate quality evidence, strong recommendation).
ESGE recommends attempting prophylactic pancreatic stenting in all patients with PGW-assisted attempts at biliary cannulation (moderate quality evidence, strong recommendation).
4
ESGE recommends needle-knife fistulotomy as the preferred technique for precutting (moderate quality evidence, strong recommendation).
ESGE suggests that precutting should be used only by endoscopists who achieve selective biliary cannulation in more than 80 % of cases using standard cannulation techniques (low quality evidence, weak recommendation).
When access to the pancreatic duct is easy to obtain, ESGE suggests placement of a pancreatic stent prior to precutting (moderate quality evidence, weak recommendation).
5
ESGE recommends that in patients with a small papilla that is difficult to cannulate, transpancreatic biliary sphincterotomy should be considered if unintentional insertion of a guidewire into the pancreatic duct occurs (moderate quality evidence, strong recommendation).
In patients who have had transpancreatic sphincterotomy, ESGE suggests prophylactic pancreatic stenting (moderate quality evidence, strong recommendation).
6
ESGE recommends that mixed current is used for sphincterotomy rather than pure cut current alone, as there is a decreased risk of mild bleeding with the former (moderate quality evidence, strong recommendation).
7
ESGE suggests endoscopic papillary balloon dilation (EPBD) as an alternative to endoscopic sphincterotomy (EST) for extracting CBD stones < 8 mm in patients without anatomical or clinical contraindications, especially in the presence of coagulopathy or altered anatomy (moderate quality evidence, strong recommendation).
8
ESGE does not recommend routine biliary sphincterotomy for patients undergoing pancreatic sphincterotomy, and suggests that it is reserved for patients in whom there is evidence of coexisting bile duct obstruction or biliary sphincter of Oddi dysfunction (moderate quality evidence, weak recommendation).
9
In patients with periampullary diverticulum (PAD) and difficult cannulation, ESGE suggests that pancreatic duct stent placement followed by precut sphincterotomy or needle-knife fistulotomy are suitable options to achieve cannulation (low quality evidence, weak recommendation).
ESGE suggests that EST is safe in patients with PAD. In cases where EST is technically difficult to complete as a result of a PAD, large stone removal can be facilitated by a small EST combined with EPBD or use of EPBD alone (low quality evidence, weak recommendation).
10
For cannulation of the minor papilla, ESGE suggests using wire-guided cannulation, with or without contrast, and sphincterotomy with a pull-type sphincterotome or a needle-knife over a plastic stent (low quality evidence, weak recommendation).
When cannulation of the minor papilla is difficult, ESGE suggests secretin injection, which can be preceded by methylene blue spray in the duodenum (low quality evidence, weak recommendation).
11
In patients with choledocholithiasis who are scheduled for elective cholecystectomy, ESGE suggests intraoperative ERCP with laparoendoscopic rendezvous (moderate quality evidence, weak recommendation).
ESGE suggests that when biliary cannulation is unsuccessful with a standard retrograde approach, anterograde guidewire insertion either by a percutaneous or endoscopic ultrasound (EUS)-guided approach can be used to achieve biliary access (low quality evidence, weak recommendation).
12
ESGE suggests that in patients with Billroth II gastrectomy ERCP should be performed in referral centers, with the side-viewing endoscope as a first option; forward-viewing endoscopes are the second choice in cases of failure (low quality evidence, weak recommendation).
A straight standard ERCP catheter or an inverted sphincterotome, with or without the guidewire, is recommended by ESGE for biliopancreatic cannulation in patients who have undergone Billroth II gastrectomy (low quality evidence, strong recommendation).
Endoscopic papillary ballon dilation (EPBD) is suggested as an alternative to sphincterotomy for stone extraction in the setting of patients with Billroth II gastrectomy (low quality evidence, weak recommendation).
In patients with complex post-surgical anatomy ESGE suggests referral to a center where device-assisted enteroscopy techniques are available (very low quality evidence, weak recommendation).
Wood is a natural composite material mainly consisting of three components, i.e., cellulose, hemicellulose, and lignin. It exhibits a complex hierarchical structure characterized by open channels, ...aligned in the growth direction, having specific porosity at micro-, meso-, and macro-scale, and an extended opacity, due to adsorption phenomena because of the presence of lignin and scattering, as different refractive indexes characterize its components. Even if during the historical ages some of its applications have been replaced by other materials, wood still covers a large part of common uses, which range from biomass for energy recovery to material for the building sector, or from artifacts to household/furniture manufacturing. Despite its real invention dating to 1992, only about ten years ago two independent research groups, one from the University of Maryland (USA) and the other from the Royal Institute of Technology (Sweden) rediscovered and started to thoroughly investigate the so-called transparent wood (TW). TW can be derived from almost any wood biomass through specific chemical treatments focused on lignin. These aim to completely remove this component from wood or to eliminate the chromophore groups present in the pristine material, hence obtaining, after direct densification or after infiltration with a suitable polymer resin, a new material with very high transparency, toughness, and lightness. These characteristics can further be combined with other specific features (such as environmental protection, flame retardancy, photoluminescence, and energy storage ability, among others), which open the way toward the development of new, up-to-date, advanced, and sustainable materials for both structural and functional purposes, fulfilling the current concepts of circular economy and sustainability. The present review is aimed at providing the reader with an overview of the characteristics of transparent wood, describing the latest applications and, finally, discussing some challenging issues and perspectives for possible developments in the forthcoming years.
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Among the different polymerization techniques, frontal polymerization (FP) has gained high interest from the scientific community because of its peculiar characteristics: in particular, compared to ...classic polymerization reactions, FP allows for a better exploitation of the heat of polymerization involved, without requiring any external energy input apart from an initial photo or thermal ignition that triggers the reaction. The latter usually propagates in a few tenths of seconds or (at most) minutes through a hot self-sustaining polymerization front, giving rise to the formation of fully cured thermosetting networks or thermoplastic polymers. Furthermore, different polymerization mechanisms can be involved in FP reactions, comprising cationic or anionic, ring-opening metathesis, and free-radical polymerization, among others. Further, it is possible to run FP reactions in bulk, in solution, or even using solid monomers if they are melted at the temperature of the front, notwithstanding the possibility of using reactive systems containing fillers or fiber/fabric reinforcements. In this context, the use of FP is becoming very important also for the design and production of advanced (nano)composite materials, saving processing time and achieving the completeness of the curing reaction, even in the presence of high filler/reinforcement loadings. Therefore, this mini-review aims to provide the reader with the basics of FP and its main peculiarities, even in the context of preparing high-performing composites. In this respect, some recent case studies witnessing the potentialities of frontal polymerization for the design of advanced (nano)composite systems will be elucidated. Finally, some perspectives about possible future developments will be proposed.
This review retrieves the determinant role of the solid precursor on the definition, chemistry, processing and applications of geopolymers. It is demonstrated that the process, the alkaline solution, ...the curing conditions as well as the orientation of the end-products in term of performance and potential application are governed by the intrinsic nature and characteristics of the aluminosilicate precursors. In particular, the amorphous fraction and the available Al and Si cations governs the geopolymerization. Solid precursors with relatively large amount of amorphous phase are easily activated with standard alkaline solution (6–8 M) leading to the formation of a gel, designated as cement or binder. Al-rich gels are efficient for the design of high strength concretes or composites. Solid precursors with low amorphous fraction need relatively high concentrated alkaline solution (>8 M), particularly aluminosilicates with crystalline habitus such as fly ash, volcanic ash, feldspars, granites, nepheline, etc. In these cases, both the dissolution and the curing steps require temperature above ambient. The pastes produced are dominated by non-reacted or incongruently dissolved particles more addressed for mortars and precast. When high concentrated alkaline solution is used, some additions of Si-rich or Al-rich reactive materials are needed to stabilize the extra alkali present within the matrix: steam or long-term curing are, therefore, required. Regarding the curing conditions, the temperature and relative humidity to be applied are directly linked to the nature of the solid precursor. This paper should be viewed as a significant contribution for the understanding and classification of geopolymer cement and composites as well as the science and technology of the geopolymers.
•Solid precursor for geopolymers has individual or synergetic, active, semi-active, pozzolanic or inert behavior.•Geopolymer process and end-products are strongly linked to the nature of raw solid.• precursors•Classification of the solid precursors results on the optimization of the sustainability of.• geopolymers
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