Current Opinion and Practice on Peritoneal Carcinomatosis Management: The North African Perspective.

Background: The status of peritoneal surface malignancy (PSM) management in North Africa is undetermined. The aim of this study was to assess and compare current practice and knowledge regarding PSM and examine satisfaction with available treatment options and need for alternative therapies in North Africa. Methods: This is a qualitative study involving specialists participating in PSM management in North Africa. The survey analyzed demographic characteristics and current knowledge and opinions regarding PSM management in different institutions. We also looked at goals and priorities, satisfaction with treatment modalities and heated intraperitoneal chemotherapy (HIPEC) usefulness according to specialty, country, years of experience, and activity sector. Results: One-hundred and three participants responded to the survey (response rate of 57%), including oncologists and surgeons. 59.2% of respondents had more than 10 years experience and 45.6% treated 20-50 PSM cases annually. Participants satisfaction with PSM treatment modalities was mild for gastric cancer (3/10 [IQR 2-3]) and moderate for colorectal (5/10 [IQR 3-5]), ovarian (5/10 [IQR 3-5]), and pseudomyxoma peritonei (5/10 [IQR 3-5]) type of malignancies. Good quality of life and symptom relief were rated as main priorities for treatment and the need for new treatment modalities was rated 9/10 [IQR 8-9]. The perceived usefulness of systemic chemotherapy in first intention was described as high by 42.7 and 39.8% of respondents for PSM of colorectal and gastric origins, while HIPEC was described as highly useful for ovarian (49.5%) and PMP (73.8) malignancies. Conclusions: The management of PSM in the North African region has distinct differences in knowledge, treatments availability and priorities. Disparities are also noted according to specialty, country, years of expertise, and activity sector. The creation of referral structures and PSM networks could be a step forward to standardized PSM management in the region.

Predictive factors of disease-free survival after complete pathological response to neoadjuvant radiotherapy for rectal adenocarcinoma: retrospective case series.

BACKGROUND: Many data suggest that patients with low rectal adenocarcinoma who achieved ypT0N0 status have improved survival and disease-free survival (DFS) compared to all other stages however only few data are available regarding the specific prognosis factors of this subgroup. This study aimed to evaluate predictive factors for disease free survival after complete pathological response (CPR) in cases of low rectal adenocarcinoma. MATERIALS AND METHODS: From January 2005 to December 2013, all patients with low rectal adenocarcinoma who underwent neoadjuvant chemoradiotherapy followed by total mesorectal excision and achieved CPR were included at 7 Moroccan and 1 Algerian centres. Predictive factors for disease-free survival were analysed by uni and multivariate analysis. RESULTS: Eigthy-four (12.1%) patients achieved a CPR (ypT0N0). Multivariate analysis revealed that both poorly differentiated tumors (OR, 9.23; 95 CI 1.35-62.82; P = 0.023) and the occurrence of perineal sepsis (OR, 13.51; 95 CI 1.96-93.12; P = 0.008) were independently associated with impaired DFS. CONCLUSIONS: Patients with low rectal cancer who exhibited a CPR after neoadjuvant therapy have good prognoses; however, the occurrence of perineal sepsis and/or poor initial differentiation may be associated with impaired DFS in these patients. TRIAL REGISTRATION: The study was retrospectively registered the 28th July 2018 in ClinicalTrials.gov register with the reference NCT03601689.

Large positive in-plane magnetoresistance induced by localized states at nanodomain boundaries in graphene.

Graphene supports long spin lifetimes and long diffusion lengths at room temperature, making it highly promising for spintronics. However, making graphene magnetic remains a principal challenge despite the many proposed solutions. Among these, graphene with zig-zag edges and ripples are the most promising candidates, as zig-zag edges are predicted to host spin-polarized electronic states, and spin-orbit coupling can be induced by ripples. Here we investigate the magnetoresistance of graphene grown on technologically relevant SiC/Si(001) wafers, where inherent nanodomain boundaries sandwich zig-zag structures between adjacent ripples of large curvature. Localized states at the nanodomain boundaries result in an unprecedented positive in-plane magnetoresistance with a strong temperature dependence. Our work may offer a tantalizing way to add the spin degree of freedom to graphene.

Surface enhanced Raman scattering of monolayer MX2 with metallic nano particles.

Monolayer transition metal dichalcogenides MX2 (M = Mo, W; X = S) exhibit remarkable electronic and optical properties, making them candidates for application within flexible nano-optoelectronics. The ability to achieve a high optical signal, while quantitatively monitoring strain in real-time is the key requirement for applications in flexible sensing and photonics devices. Surface-enhanced Raman scattering (SERS) allows us to achieve both simultaneously. However, the SERS depends crucially on the size and shape of the metallic nanoparticles (NPs), which have a large impact on its detection sensitivity. Here, we investigated the SERS of monolayer MX2, with particular attention paid to the effect of the distribution of the metallic NPs. We show that the SERS depends crucially on the distribution of the metallic NPs and also the phonon mode of the MX2. Moreover, strong coupling between MX2 and metallic NPs, through surface plasmon excitation, results in splitting of the and modes and an additional peak becomes apparent. For a WS2-Ag system the intensity of the additional peak increases exponentially with local strain, which opens another interesting window to quantitatively measure the local strain using SERS. Our experimental study may be useful for the application of monolayer MX2 in flexible nano-optoelectronics.

Impact of Conversion to Open Surgery on Early Postoperative Morbidity After Laparoscopic Resection for Rectal Adenocarcinoma: A Retrospective Study.

BACKGROUND: The impact of conversion to open surgery after a laparoscopic resection for rectal adenocarcinoma on postoperative morbidity is still unclear. Most previous studies included colon and rectal carcinomas and produced conflicting results. The aim of this study was to investigate the impact of conversion to open surgery on early postoperative morbidity in patients who underwent a laparoscopic resection for rectal adenocarcinoma. METHODS: This was a retrospective bicentric study. It included all consecutive patients who underwent a laparoscopic resection for nonmetastatic rectal adenocarcinoma between January 2005 and December 2013. The impact of conversion to open surgery on 30-day postoperative morbidity was analyzed by univariate and multivariate analyses. Risk factors for conversion were also investigated by univariate and multivariate analyses. RESULTS: One hundred thirty-one patients were included. The conversion rate was 26.7%. The global 30-day morbidity rate was 31.3% (41 patients). The conversion to open surgery was associated with higher rates of postoperative complications, anastomotic leaks, and reoperations. It was also an independent predictive factor to postoperative morbidity in the multivariate analysis (P = .01; odds ratio 2.86; 95% confidence interval [CI] 1.23-6.63), in addition to T4 tumors (P = .04; odds ratio 3.92; 95% CI 1.05-14.61). Risk factors for conversion in the multivariate analysis were T4 tumors (P = .006; odds ratio 6.09; 95% CI 1.66-22.32) and the height of the tumor (P = .025; odds ratio 2.7; 95% CI 1.13-6.43). CONCLUSIONS: This study showed that conversion to open surgery after laparoscopic proctectomy for rectal adenocarcinoma was associated with higher rates of early postoperative complications. It also showed that T4 tumors and the height of the tumor were independent factors associated with the conversion to open surgery. Reducing postoperative morbidity could be achieved by a better patient selection and a policy of early conversion.

Spin-dependent transport properties of Fe3O4/MoS2/Fe3O4 junctions.

Magnetite is a half-metal with a high Curie temperature of 858 K, making it a promising candidate for magnetic tunnel junctions (MTJs). Yet, initial efforts to exploit its half metallic nature in Fe3O4/MgO/Fe3O4 MTJ structures have been far from promising. Finding suitable barrier layer materials, which keep the half metallic nature of Fe3O4 at the interface between Fe3O4 layers and barrier layer, is one of main challenges in this field. Two-dimensional (2D) materials may be good candidates for this purpose. Molybdenum disulfide (MoS2) is a transition metal dichalcogenide (TMD) semiconductor with distinctive electronic, optical, and catalytic properties. Here, we show based on the first principle calculations that Fe3O4 keeps a nearly fully spin polarized electron band at the interface between MoS2 and Fe3O4. We also present the first attempt to fabricate the Fe3O4/MoS2/Fe3O4 MTJs. A clear tunneling magnetoresistance (TMR) signal was observed below 200 K. Thus, our experimental and theoretical studies indicate that MoS2 can be a good barrier material for Fe3O4 based MTJs. Our calculations also indicate that junctions incorporating monolayer or bilayer MoS2 are metallic.

Transport Gap Opening and High On-Off Current Ratio in Trilayer Graphene with Self-Aligned Nanodomain Boundaries.

Trilayer graphene exhibits exceptional electronic properties that are of interest both for fundamental science and for technological applications. The ability to achieve a high on-off current ratio is the central question in this field. Here, we propose a simple method to achieve a current on-off ratio of 10(4) by opening a transport gap in Bernal-stacked trilayer graphene. We synthesized Bernal-stacked trilayer graphene with self-aligned periodic nanodomain boundaries (NBs) on the technologically relevant vicinal cubic-SiC(001) substrate and performed electrical measurements. Our low-temperature transport measurements clearly demonstrate that the self-aligned periodic NBs can induce a charge transport gap greater than 1.3 eV. More remarkably, the transport gap of ∼0.4 eV persists even at 100 K. Our results show the feasibility of creating new electronic nanostructures with high on-off current ratios using graphene on cubic-SiC.

Nanopatterning and Electrical Tuning of MoS2 Layers with a Subnanometer Helium Ion Beam.

We report subnanometer modification enabled by an ultrafine helium ion beam. By adjusting ion dose and the beam profile, structural defects were controllably introduced in a few-layer molybdenum disulfide (MoS2) sample and its stoichiometry was modified by preferential sputtering of sulfur at a few-nanometer scale. Localized tuning of the resistivity of MoS2 was demonstrated and semiconducting, metallic-like, or insulating material was obtained by irradiation with different doses of He(+). Amorphous MoSx with metallic behavior has been demonstrated for the first time. Fabrication of MoS2 nanostructures with 7 nm dimensions and pristine crystal structure was also achieved. The damage at the edges of these nanostructures was typically confined to within 1 nm. Nanoribbons with widths as small as 1 nm were reproducibly fabricated. This nanoscale modification technique is a generalized approach that can be applied to various two-dimensional (2D) materials to produce a new range of 2D metamaterials.

Enhanced Shubnikov-De Haas Oscillation in Nitrogen-Doped Graphene.

N-doped graphene displays many interesting properties compared with pristine graphene, which makes it a potential candidate in many applications. Here, we report that the Shubnikov-de Haas (SdH) oscillation effect in graphene can be enhanced by N-doping. We show that the amplitude of the SdH oscillation increases with N-doping and reaches around 5k Ω under a field of 14 T at 10 K for highly N-doped graphene, which is over 1 order of magnitude larger than the value found for pristine graphene devices with the same geometry. Moreover, in contrast to the well-established standard Lifshitz-Kosevich theory, the amplitude of the SdH oscillation decreases linearly with increasing temperature and persists up to a temperature of 150 K. Our results also show that the magnetoresistance (MR) in N-doped graphene increases with increasing temperature. Our results may be useful for the application of N-doped graphene in magnetic devices.

Magnetic and transport properties of epitaxial thin film MgFe2O4 grown on MgO (100) by molecular beam epitaxy.

Magnesium ferrite is a very important magnetic material due to its interesting magnetic and electrical properties and its chemical and thermal stability. Here we report on the magnetic and transport properties of epitaxial MgFe2O4 thin films grown on MgO (001) by molecular beam epitaxy. The structural properties and chemical composition of the MgFe2O4 films were characterized by X-Ray diffraction and X-Ray photoelectron spectroscopy, respectively. The nonsaturation of the magnetization in high magnetic fields observed for M (H) measurements and the linear negative magnetoresistance (MR) curves indicate the presence of anti-phase boundaries (APBs) in MgFe2O4. The presence of APBs was confirmed by transmission electron microscopy. Moreover, post annealing decreases the resistance and enhances the MR of the film, suggesting migration of the APBs. Our results may be valuable for the application of MgFe2O4 in spintronics.