The role of chemical and microstructural inhomogeneities on interface magnetism.

The study of interfacing effects arising when different magnetic phases are in close contact has led to the discovery of novel physical properties and the development of innovative technological applications of nanostructured magnetic materials. Chemical and microstructural inhomogeneities at the interfacial region, driven by interdiffusion processes, chemical reactions and interface roughness may significantly affect the final properties of a material and, if suitably controlled, may represent an additional tool to finely tune the overall physical properties. The activity at the Nanostructured Magnetic Materials Laboratory (nM2-Lab) at CNR-ISM of Italy is aimed at designing and investigating nanoscale-engineered magnetic materials, where the overall magnetic properties are dominated by the interface exchange coupling. In this review, some examples of recent studies where the chemical and microstructural properties are critical in determining the overall magnetic properties in core/shell nanoparticles, nanocomposites and multilayer heterostructures are presented.

Perpendicularly magnetized Co/Pd-based magneto-resistive heterostructures on flexible substrates.

Flexible magneto-resistive heterostructures have received a great deal of attention over the past few years as they allow for new product paradigms that are not possible with conventional rigid substrates. While the progress and development of systems with longitudinal magnetic anisotropy on non-planar substrates has been remarkable, flexible magneto-resistive heterostructures with perpendicular magnetic anisotropy (PMA) have never been studied despite the possibility to obtain additional functionality and improved performance. To fill this gap, flexible PMA Co/Pd-based giant magneto-resistive (GMR) spin-valve stacks were prepared by using an innovative transfer-and-bonding strategy exploiting the low adhesion of a gold underlayer to SiO x /Si(100) substrates. The approach allows overcoming the limits of the direct deposition on commonly used polymer substrates, whose high surface roughness and low melting temperature could hinder the growth of complex heterostructures with perpendicular magnetic anisotropy. The obtained PMA flexible spin-valves show a sizeable GMR ratio (∼1.5%), which is not affected by the transfer process, and a high robustness against bending as indicated by the slight change of the magneto-resistive properties upon bending, thus allowing for their integration on curved surfaces and the development of a novel class of advanced devices based on flexible magneto-resistive structures with perpendicular magnetic anisotropy. Besides endowing the family of flexible electronics with PMA magneto-resistive heterostructures, the exploitation of the results might apply to high temperature growth processes and to the fabrication of other functional and flexible multilayer materials engineered at the nanoscale.

Correction to: Inflammatory bowel disease (IBD) position statement of the Italian Society of Colorectal Surgery (SICCR): general principles of IBD management.

The affiliation of the author Silvio Danese has been incorrectly published in the original publication. The complete correct affiliation should read as follows.

Correction to: Inflammatory bowel disease position statement of the Italian Society of Colorectal Surgery (SICCR): Crohn's disease.

The affiliation of the author Silvio Danese has been incorrectly published in the original publication.

Inflammatory bowel disease position statement of the Italian Society of Colorectal Surgery (SICCR): Crohn's disease.

The Italian Society of Colorectal Surgery (SICCR) promoted the project reported here, which consists of a position statement of Italian colorectal surgeons to address the surgical aspects of Crohn's disease management. Members of the society were invited to express their opinions on several items proposed by the writing committee, based on evidence available in the literature. The results are presented, focusing on relevant points. The present paper is not an alternative to available guidelines; rather, it offers a snapshot of the attitudes of SICCR surgeons about the surgical treatment of Crohn's disease. The committee was able to identify some points of major disagreement and suggested strategies to improve quality of available data and acceptance of guidelines.

Inflammatory bowel disease (IBD) position statement of the Italian Society of Colorectal Surgery (SICCR): general principles of IBD management.

The Italian Society of Colorectal Surgery (SICCR) promoted the project reported here, which consists of a Position Statement of Italian colorectal surgeons to address the surgical aspects of inflammatory bowel disease management. Members of the society were invited to express their opinions on several items proposed by the writing committee, based on evidence available in the literature. The results are presented, focusing on relevant points. The present paper is not an alternative to available guidelines; rather, it offers a snapshot of the attitudes of SICCR surgeons about the general principles of surgical treatment of inflammatory bowel disease. The committee was able to identify some points of major disagreement and suggested strategies to improve quality of available data and acceptance of guidelines.

Co/Pd-Based synthetic antiferromagnetic thin films on Au/resist underlayers: towards biomedical applications.

Thin film stacks consisting of multiple repeats M of synthetic antiferromagnetic (SAF) [Co/Pd]N/Ru/[Co/Pd]N units with perpendicular magnetic anisotropy were explored as potential starting materials to fabricate free-standing micro/nanodisks, which represent a promising candidate system for theranostic applications. The films were directly grown on a sacrificial resist layer spin-coated on SiOx/Si(100) substrates, required for the preparation of free-standing disks after its dissolution. Furthermore, the film stack was sandwiched between two Au layers to allow further bio-functionalization. For M ≤ 5, the samples fulfill all the key criteria mandatory for biomedical applications, i.e., zero remanence, zero field susceptibility at small fields and sharp switching to saturation, together with the ability to vary the total magnetic moment at saturation by changing the number of repetitions of the multi-stack. Moreover, the samples show strong perpendicular magnetic anisotropy, which is required for applications relying on the transduction of a mechanical force through the micro/nano-disks under a magnetic field, such as the mechanical cell disruption, which is nowadays considered a promising alternative to the more investigated magnetic hyperthermia approach for cancer treatment. In a further step, SAF microdisks were prepared from the continuous multi-stacks by combining electron beam lithography and Ar ion milling, revealing similar magnetic properties as compared to the continuous films.

The interplay between single particle anisotropy and interparticle interactions in ensembles of magnetic nanoparticles.

This paper aims to analyze the competition of single particle anisotropy and interparticle interactions in nanoparticle ensembles using a random anisotropy model. The model is first applied to ideal systems of non-interacting and strongly dipolar interacting ensembles of maghemite nanoparticles. The investigation is then extended to more complex systems of pure cobalt ferrite CoFe2O4 (CFO) and mixed cobalt-nickel ferrite (Co,Ni)Fe2O4 (CNFO) nanoparticles. Both samples were synthetized by the polyol process and exhibit the same particle size (DTEM ≈ 5 nm), but with different interparticle interaction strengths and single particle anisotropy. The implementation of the random anisotropy model allows investigation of the influence of single particle anisotropy and interparticle interactions, and sheds light on their complex interplay as well as on their individual contribution. This analysis is of fundamental importance in order to understand the physics of these systems and to develop technological applications based on concentrated magnetic nanoparticles, where single and collective behaviors coexist.

L10-FeNi films on Au-Cu-Ni buffer-layer: a high-throughput combinatorial study.

The fct L10-FeNi alloy is a promising candidate for the development of high performance critical-elements-free magnetic materials. Among the different materials, the Au-Cu-Ni alloy has resulted very promising; however, a detailed investigation of the effect of the buffer-layer composition on the formation of the hard FeNi phase is still missing. To accelerate the search of the best Au-Cu-Ni composition, a combinatorial approach based on High-Throughput (HT) experimental methods has been exploited in this paper. HT magnetic characterization methods revealed the presence of a hard magnetic phase with an out-of-plane easy-axis, whose coercivity increases from 0.49 kOe up to 1.30 kOe as the Au content of the Cu-Au-Ni buffer-layer decreases. Similarly, the out-of-plane magneto-crystalline anisotropy energy density increases from 0.12 to 0.35 MJ/m3. This anisotropy is attributed to the partial formation of the L10 FeNi phase induced by the buffer-layer. In the range of compositions we investigated, the buffer-layer structure does not change significantly and the modulation of the magnetic properties with the Au content in the combinatorial layer is mainly related to the different nature and extent of interlayer diffusion processes, which have a great impact on the formation and order degree of the L10 FeNi phase.

Comparative study between linear and non-linear frequency-modulated pulse-compression thermography.

Pulse-compression thermography is an emerging non-destructive technique whose effectiveness strictly depends on the choice of the coded excitations used to modulate the heating stimulus. In this paper, the features of frequency-modulated coded signals, i.e., chirps, have been tested for imaging thin Teflon defects embedded within a carbon fiber composite specimen. With the aim of maximizing the heat transferred within the sample, the use of several optimized non-linear chirp signals has been also investigated and their defect detection capability compared in terms of the maximum achievable signal-to-noise ratio.

Detection of rebars in concrete using advanced ultrasonic pulse compression techniques.

A pulse compression technique has been developed for the non-destructive testing of concrete samples. Scattering of signals from aggregate has historically been a problem in such measurements. Here, it is shown that a combination of piezocomposite transducers, pulse compression and post processing can lead to good images of a reinforcement bar at a cover depth of 55 mm. This has been achieved using a combination of wide bandwidth operation over the 150-450 kHz range, and processing based on measuring the cumulative energy scattered back to the receiver. Results are presented in the form of images of a 20 mm rebar embedded within a sample containing 10 mm aggregate.

From Mn3O4/MnO core-shell nanoparticles to hollow MnO: evolution of magnetic properties.

Manganese oxide nanoparticles (MNOPs), when dispersed in a water solution, show a magnetic behavior that drastically changes after an aging process. In this paper, the variation in the magnetic properties has been correlated with the structural evolution of the nanoparticles: in particular, the as prepared Mn3O4/MnO core/shell system manifests a low temperature magnetization reversal that is strongly affected by the presence of the MnO shell and, in particular, by the existence of a frustrated interfacial region playing a key role in determining the low temperature irreversibility, the finite coercivity slightly above the Curie temperature of the Mn3O4 phase and the horizontal displacement of the FC-hysteresis loop. On the other hand, the magnetic behavior of the aged system results dominated by the presence of Mn3O4 whose highly anisotropic character (i.e. high coercivity and high magnetization remanence) is attributed to the presence of a large fraction of surface spins. Such a result is consistent with the structural evolution, from core/shell to hollow nanoparticles, as shown by TEM observation.

Superspin glass state in a diluted nanoparticle system stabilized by interparticle interactions mediated by an antiferromagnetic matrix.

In nanoparticle systems consisting of two magnetic materials (bi-magnetic nanoparticles or nanoparticles embedded in a magnetic matrix), there is a constantly growing interest in the investigation of the interplay between interparticle interactions and the nanoparticle-matrix interface exchange coupling, because of its enormous impact on a number of technological applications. The understanding of the mechanisms of such interplay is a great challenge, as it would allow controlling equilibrium and non-equilibrium magnetization dynamics of exchange coupled nanoparticles systems and finely tuning their anisotropy. Here, we provide evidence that this interplay leads to a collective superspin glass (SSG) behavior in a system of diluted ferromagnetic (FM) nanoparticles embedded in an antiferromagnetic (AFM) matrix (5% volume fraction of Co particles in Mn film matrix). We have developed a novel mesoscopic model to study the influence of interparticle interaction on the exchange bias (EB) and the dynamical behavior of assemblies of FM nanoparticles embedded in a granular AFM matrix. Our mesoscopic model is based on reducing the amount of simulated spins to the minimum number necessary to describe the magnetic structure of the system and introducing the adequate exchange parameters between the different spins. The model replicates remarkably well the observed static and dynamical SSG properties as well as the EB behavior. In addition, the proposed model well explains the role of the significant Co/Mn alloying and of the granularity of the matrix in mediating interparticle interactions through exchange and dipole-dipole coupling between the uncompensated moments of its grains and the exchange interaction at the Co/Mn interface.

Risk of permanent stoma in extensive Crohn's colitis: the impact of biological drugs.

AIM: The overall risk of permanent stoma was determined in patients with extensive Crohn's colitis. An attempt was made to analyse whether biological drugs have modified the surgical approach in patients with anorectal involvement. METHOD: In all, 233 patients with Crohn's disease colitis operated on between 1995 and 2010 were reviewed retrospectively. Fifty-one were treated before 2002 (prebiological era) and 182 after 2002 (biological era). The relationship was determined between the use of immunosuppressors, biological drugs, the presence of perianal disease and anorectal stenosis and the rate of permanent stoma formation. RESULTS: In the prebiological era 23 (45.1%) patients without anorectal involvement underwent colectomy and ileorectal anastomosis, 17 (33.3%) with severe anorectal disease had proctocolectomy and 11 (21.6%) with anorectal involvement had abdominal colectomy with permanent ileostomy. In the biological era 73 (40.1%) patients without anorectal involvement underwent colectomy and ileorectal anastomosis, nine (5%) with severe anorectal involvement had proctocolectomy and 100 (54.9%) with anorectal involvement had colectomy with terminal ileostomy. Of these 100, 75 have subsequently been treated with biological drugs with full regression of anorectal lesions in 81.3%. Rates of permanent stoma in the prebiological and biological era were 60.8% and 19.2% (P < 0.001). Univariate and multivariate analysis showed that only the use of biological drugs was significantly associated with an increased rate of rectal preservation (P < 0.05). CONCLUSION: The risk of a permanent stoma in patients with Crohn's colitis and anorectal involvement is significantly reduced with combined surgical and biological treatment.

Randomized controlled trials in pouchitis.

Pouchitis is the most common complication of Proctocolectomy with ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis (UC). The diagnosis of pouchitis requires the presence of symptoms, together with characteristic endoscopic and histological abnormalities. The exact cause of pouchitis is not known. Whereas 'acute' pouchitis can be treated rapidly and successfully in the majority of patients, "refractory" and 'chronic pouchitis' remain therapeutic challenges to patients and physicians. Metronidazole and Ciprofloxacin budesonide enemas and oral probiotic therapy with VSL#3 all appear to be effective therapies for acute and/or chronic pouchitis. The medical therapy of pouchitis remains largely empiric, and additional multicenter, randomized, double-blind, placebo-con- trolled, dose-ranging trials are needed. In future trials, treatment indications such as active acute or chronic pouchitis and maintenance of remission for acute or chronic pouchitis should be clearly defined.

Magnetic interactions in silica coated nanoporous assemblies of CoFe2O4 nanoparticles with cubic magnetic anisotropy.

Magnetic interactions in silica coated spherical nanoporous assemblies of CoFe(2)O(4) nanoparticles have been investigated by low temperature field dependent remanent magnetization (M(DCD) and M(IRM)) and magnetization relaxation measurements. The synthesis procedure leads to the formation of spherical aggregates of about 50-60 nm in diameter composed of hexagonal shaped nanocrystals with shared edges. The negative deviation from the non-interacting case in the Henkel plot indicates the predominance of dipole-dipole interactions favouring the demagnetized state, although the presence of exchange interactions in the porous system cannot be excluded. The activation volume, derived from time dependent magnetization measurements, turns out to be comparable with the particle physical volume, thus indicating, in agreement with static and dynamic irreversible magnetization measurements, that the magnetization reversal actually involves individual crystals.

Oral budesonide in the treatment of chronic refractory pouchitis.

BACKGROUND: Pouchitis is the major long-term complication after ileal-pouch nal anastomosis for ulcerative colitis. Ten to 15% of patients develop a chronic pouchitis, either treatment responsive or treatment refractory. AIM: To evaluate the efficacy of oral budesonide in inducing remission and improving quality of life in patients with chronic refractory pouchitis. METHODS: Twenty consecutive patients with active pouchitis, not responding after 1 month of antibiotic treatment were treated with budesonide controlled ileal release 9 mg/day for 8 weeks. Symptomatic, endoscopic and histological evaluations were undertaken before and after treatment according to Pouchitis Disease Activity Index. Remission was defined as a combination of Pouchitis Disease Activity Index clinical score of < or = 2, endoscopic score of < or = 1 and total Pouchitis Disease Activity Index score of < or = 4. The quality of life was assessed with the Inflammatory Bowel Disease Questionnaire. RESULTS: Fifteen of 20 patients (75%) achieved remission. The median total Pouchitis Disease Activity Index scores before and after therapy were, respectively, 14 (range 9-16) and 3 (range 2-10) (P < 0.001). The median Inflammatory Bowel Disease Questionnaire score also significantly improved from 105 (range 77-175) to 180 (range 85-220) (P < 0.001). CONCLUSION: Eight-week treatment with oral budesonide appears effective in inducing remission in patients with active pouchitis refractory to antibiotic treatment in this open-label study.

CT-guided percutaneous pelvic abscess drainage in Crohn's disease.

BACKGROUND: Percutaneous abscess drainage (PAD) is the current therapy for abdominal or pelvic collections. PAD has poorer curative rate for abscesses in Crohn's disease (CD), commonly complicated by wide fistulas and multiloculations. METHODS: We retrospectively evaluated abscess cure rate, complications and final outcome in 87 CD patients, 70 with spontaneous and 17 with postoperative pelvic abscesses, all treated with CT-guided PAD during the last 7 years. RESULTS: A 77% primary success rate and an 84.3% secondary success rate were obtained without major complications. The higher success rate for PAD was for postoperative (88.2%) rather than spontaneous abscesses (74.2%). Seventy-two percent of treated patients did not develop recurrent abscesses and underwent elective surgery up to 40 months later. CONCLUSION: PAD in pelvic abscess complicating CD is an effective alternative to early surgery with satisfactory curative success rates. In unsuccessful cases, due to wide fistulas or postoperative anastomotic dehiscence, PAD helped in planning elective surgery, reducing surgical complications.