Reflectance in AFM-IR: Implications for Interpretation and Remote Analysis of the Buried Interface.

AFM-IR combines the chemical sensitivity of infrared spectroscopy with the lateral resolution of scanning probe microscopy, allowing nanoscale chemical analysis of almost any organic material under ambient conditions. As a result, this versatile technique is rapidly gaining popularity among materials scientists. Here, we report a previously overlooked source of data and artifacts in AFM-IR analysis; reflection from the buried interface. Periodic arrays of gold on glass are used to show that the overall signal in AFM-IR is affected by the wavelength-dependent reflectivity and thermal response of the underlying substrate. Excitingly, this demonstrates that remote analysis of heterogeneities at the buried interface is possible alongside that of an overlying organic film. On the other hand, AFM-IR users should carefully consider the composition and topography of underlying substrates when interpreting nanoscale infrared data. The common practice of generating ratio images, or indeed the normalization of AFM-IR spectra, should be approached with caution in the presence of substrate heterogeneity or variable sample thickness.

The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings.

Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers.

Human Amniotic Epithelial Cell Transplantation is Safe and Well Tolerated in Patients with Compensated Cirrhosis: A First-in-Human Trial.

Placenta-derived human amniotic epithelial cells (hAEC) exhibit anti-inflammatory and anti-fibrotic effects in cirrhosis models. We conducted a first-in-human phase I clinical trial to assess the safety and tolerability of hAEC in adults with compensated cirrhosis. We examined increasing and repeated doses of hAEC in 9 patients in 3 cohorts. Cohort 1 patients received 0.5 × 106/kg hAEC in one IV infusion. Cohort 2 patients received 1 × 106/kg hAEC in one IV infusion. The patients in cohort 3 received 1 × 106/kg hAEC on days 0 and 28. Here, we report follow-up to post-infusion day 56 (D56), during which no serious adverse events occurred. Six patients experienced no study-related adverse events, while 3 patients reported mild (grade 1) headaches that were possibly infusion-related. A transient decrease in serum platelet count occurred in all patients, which returned to baseline screening values by day 5. FIB-4 values to assess fibrosis were significantly lower at D56. Although not statistically significant, serum AST levels and liver stiffness measurements at D56 were lower than those at baseline. The hepatic venous pressure gradient, a measure of portal hypertension, declined in 4 patients, did not change in 3 patients, and increased in 2 patients. In conclusion, intravenous infusion of allogeneic hAEC in patients with compensated cirrhosis at the doses used in this study was safe and well tolerated, with no difference observed between 1 and 2 doses. Decreased hepatic inflammation, liver stiffness, and portal hypertension support larger studies aimed at identifying patients who may benefit from this therapy. Clinical Trial registration: The trial was prospectively entered on the Australian Clinical Trials Registry (ANZCTR12616000437460).

Functional recovery from refractory hepatic encephalopathy following angiographic obliteration of a large, spontaneous portal-umbilical portosystemic shunt: a case report.

BACKGROUND: Hepatic encephalopathy (HE) as a consequence of cirrhosis with portal hypertension has a profound impact on quality of life for both patients and caregivers, has no gold-standard diagnostic test, and is a risk factor for mortality. Spontaneous portosystemic shunts (SPSS) are common in patients with cirrhosis, can be challenging to identify, and in some cases, can drive refractory HE. Cross-sectional shunt size greater than 83mm2 is associated with liver disease severity, overt HE, and mortality. CASE PRESENTATION: We report a patient with refractory HE and frequent hospitalization in the context of an occult spontaneous portal-umbilical portosystemic shunt with an estimated cross-sectional area of 809mm2. Following identification and angiographic retrograde transvenous obliteration of the SPSS using plugs, coils and sclerosant, there was improvement in neurocognitive testing and no further hospitalization for HE. CONCLUSION: SPSS in the context of cirrhosis with portal hypertension can contribute to the debilitating effects of refractory HE. This case highlights the opportunity to search for SPSS in patients with HE unresponsive to therapy as angiographic obliteration is usually safe, well-tolerated, and clinically effective.

Refractory portal hypertension complications successfully managed by parallel transjugular intrahepatic portosystemic shunt (TIPS): a case report.

BACKGROUND: Transjugular intrahepatic portosystemic shunt (TIPS) is an established intervention to treat complicated portal hypertension refractory to medical or endoscopic management. TIPS dysfunction results in the recurrence of portal hypertension symptoms. In cases of TIPS dysfunction or persistent portal hypertension despite a patent primary TIPS, the creation of parallel TIPS may be the only intervention to effectively reduce portal pressure. Since the introduction of dedicated TIPS stents (Viatorr®) the incidence of TIPS dysfunction has reduced profoundly. Nevertheless, the creation of a parallel TIPS can still be necessary in the current dedicated TIPS stent era. CASE PRESENTATION: We report one such patient who experienced ongoing portal hypertension induced upper gastro-intestinal haemorrhage despite multiple TIPS revisions and a patent primary TIPS. CONCLUSION: Following creation of a parallel TIPS, the patient remains in clinical remission with no further bleeding.

Molecular origins of Epoxy-Amine/Iron oxide interphase formation.

HYPOTHESIS: Interphase properties in composites, adhesives and protective coatings can be predicted on the basis of interfacial interactions between polymeric precursor molecules and the inorganic surface during network formation. The strength of molecular interactions is expected to determine local segmental mobility (polymer glass transition temperature, Tg) and cure degree. EXPERIMENTS: Conventional analysis techniques and atomic force microscopy coupled with infrared (AFM-IR) are applied to nanocomposite specimens to precisely characterise the epoxy-amine/iron oxide interphase, whilst molecular dynamics simulations are applied to identify the molecular interactions underpinning its formation. FINDINGS: Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and high-resolution AFM-IR mapping confirm the presence of nanoscale under-cured interphase regions. Interfacial segregation of the molecular triethylenetetraamine (TETA) cross-linker results in an excess of epoxy functionality near synthetic hematite, (Fe2O3) magnetite (Fe3O4) and goethite (Fe(O)OH) particle surfaces. This occurs independently of the variable surface binding energies, as a result of entropic segregation during the cure. Thermal analysis and molecular dynamics simulations demonstrate that restricted segmental motion is imparted by strong interfacial binding between surface Fe sites in goethite, where the position of surface hydroxyl protons enables synergistic hydrogen bonding and electrostatic binding to Fe atoms at specific sites. This provides a strong driving force for molecular orientation resulting in significantly raised Tg values for the goethite composite samples.

Infusion of reconstituted high-density lipoprotein leads to acute changes in human atherosclerotic plaque.

Studies have shown a reduction in plaque volume and change in plaque ultrasound characteristics after 4 infusions of reconstituted high-density lipoprotein (rHDL). Whether rHDL infusion leads to acute changes in plaque characteristics in humans is not known. Patients with claudication scheduled for percutaneous superficial femoral artery revascularization were randomized to receive 1 intravenous infusion of either placebo or rHDL (80 mg/kg given over 4 hours). Five to 7 days following the infusion, patients returned and revascularization was performed including atherectomy to excise plaque from the superficial femoral artery. Twenty patients (17 males) average age, 68+/-10 years (mean+/-SD) were recruited. Eleven patients had a history of documented coronary artery disease, all patients were on aspirin, and 18 were on statins. Ten of the patients received rHDL and 10 placebo. There was significantly less vascular cell adhesion molecule-1 expression (28+/-3% versus 50+/-3%; P<0.05) and a reduction in lipid content in the plaque of HDL-treated subjects compared to placebo. The level of HDL cholesterol increased by 20% after infusion of rHDL and the capacity of apolipoprotein B-depleted plasma to support cholesterol efflux increased. Intravenous infusion of a single dose of reconstituted HDL led to acute changes in plaque characteristics with a reduction in lipid content, macrophage size, and measures of inflammation. These changes may contribute to the cardioprotective effects of HDL.

Short- and long-term retrievability of the Celect vena cava filter: results from a multi-institutional registry.

PURPOSE: To evaluate retrievability of the Celect vena cava filter over time and to assess the safety of the retrieval procedure in a prospective multicenter registry. MATERIALS AND METHODS: Between October 2005 and March 2008, Celect filters were placed in 95 patients (61 men; mean age, 51 years +/- 18.5) with a temporary need for an inferior vena cava (IVC) filter. All patients satisfied requirements for filter placement; the primary indications for placement were pulmonary embolism (PE) with a contraindication to or failure of anticoagulation (n = 40), high risk for further PE (n = 29), trauma (n = 23), or massive PE with residual deep vein thrombosis and risk for further PE (n = 3). Filter orientation, vena cava injury, and other device-related incidents were evaluated at implantation and retrieval. The degree of difficulty associated with retrieval was also assessed. RESULTS: Filter retrieval was attempted in 58 patients (mean indwell time of 179 days; median, 168.5 d; range, 5-466 d). Fifty-six filters (96.6%) were successfully retrieved. Unsuccessful retrieval attempts were attributed to filter tilt (n = 1) or excessive tissue growth with the hook embedded in the endothelium (n = 1). No adverse events were associated with the inability to retrieve these filters. A Kaplan-Meier product-limit survival estimate revealed that the probability of successful filter retrieval remained at 100% at 50 weeks and at more than 74% at 55 weeks after implantation. No adverse events were related to the retrieval procedures. CONCLUSIONS: Retrieval of the Celect filter was performed safely as long as 466 days after implantation.

Multi-modal plasma focused ion beam serial section tomography of an organic paint coating.

Pigment distributions have a critical role in the corrosion protection properties of organic paint coatings, but they are difficult to image in 3D over statistically significant volumes and at sufficiently high spatial resolutions required for detailed analysis. Here we report, for the first time, large volume analytical serial sectioning tomography of an organic composite coating using a xenon Plasma Focused Ion Beam (PFIB) combined with secondary electron imaging, energy dispersive X-ray (EDX) spectrum imaging (SI) and electron backscattered diffraction (EBSD). Together these techniques provide a comprehensive quantitative description of the physical orientation and distribution of the pigments within a model marine ballast tank coating, as well as their crystallographic and elemental characterisation. Polymers and organic materials are challenging because of their propensity for ion beam damage and possible beam heating effects. Our novel, optimised block preparation technique permits automated data acquisition with minimal operator intervention, and can have significant applications for the structural and chemical characterisation of a wide range of organic materials. Our results revealed that the paint contained 7.5 vol% aluminium flakes and 25 vol% quartz particles. The aluminium flakes were oriented parallel to the substrate surface, which is beneficial in terms of the corrosion protection capability of the coating.

The Unexpected Role of Carbonate Impurities in Polyphosphate Corrosion Inhibition.

Polyphosphate corrosion inhibitors are increasingly marketed as chromate replacements for coil coated steel. The mechanisms underpinning corrosion prevention by these species is, however, not fully understood; corrosion inhibition is ordinarily assessed using electrochemical techniques, followed by ex-situ surface analysis. As a result, the formation of a clear film over cathodic sites is known to contribute to corrosion prevention, but little is known about its formation. Here, we apply advanced microscopy techniques (in-situ fluid cell AFM, SEM-EDX, and AFM-IR nano-chemical analysis) to examine early cathodic film formation by strontium aluminium polyphosphate (SAPP) in detail. For a model cut edge system, it is found that cathodic inhibition dominates during the first 24 hours of immersion, and surprisingly, that strontium carbonate impurities play a significant role. Rapidly precipitated zinc carbonate provides protection almost immediately after immersion, before the film structure evolves to include (poly)phosphate species. This suggests that the purposeful inclusion of carbonates may provide a new, environmentally sound approach to enhancing inhibitor efficacy.

Uterine artery embolisation - a treatment alternative for women with fibroids.

BACKGROUND: Fibroids are a common benign tumour of the female reproductive tract. Uterine artery embolisation is a minimally invasive catheter based technique that compares favourably with surgical treatments. OBJECTIVE: Uterine artery embolisation is an intervention that is especially suited to women who wish to preserve their uterus. This article briefly outlines the medical and surgical treatment options for fibroids with an in depth focus on fibroid embolisation. DISCUSSION: Australian interventional radiologists have been performing uterine artery embolisation for fibroid disease successfully for a number of years. This procedure - like any intervention - is not without complication, but it does enable women a valid alternative treatment pathway for fibroids. General practitioners can discuss the procedure with their local interventional radiologist and can foster a broader understanding of the process with their female patients when considering treatment options.

Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR.

The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analyzed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation.

Managing central venous obstruction in cystic fibrosis recipients--lung transplant considerations.

BACKGROUND: The superior vena cava (SVC) syndrome in cystic fibrosis (CF) patients is rare, but presents unique challenges in the peri-transplant period. We reviewed our experience of SVC syndrome in CF recipients undergoing lung transplantation. METHODS: This is a retrospective case series from a single center chart-review. SVC obstruction is defined by clinically significant stenosis or obstruction of the SVC as detected by contrast studies. RESULTS: We identified SVC obstruction in seven post-transplant cases and one pre-transplant case. All eight patients had previous or current history of indwelling central venous catheters. Three recipients experienced operative complications. Five of the seven recipients suffered at least one episode of post-operative SVC obstruction or bleeding despite prophylactic anticoagulation. At a median follow-up of 29 months, six of the seven patients transplanted are well. CONCLUSIONS: Strategies are available to minimize the risks of intra/peri-operative acute life-threatening SVC obstruction in CF patients.

Endovascular closure of ascending aortic pseudoaneurysm with a type II Amplatzer vascular plug.

A 71-year-old man initially presented with an asymptomatic, incidentally detected ascending aortic pseudoaneurysm 25 years following aortic root repair with mechanical aortic valve replacement. This pseudoaneurysm was previously treated with coil embolization but due to coil impaction it reopened 8 years later. Endovascular closure of the pseudoaneurysm was achieved with the off-label use of a type II Amplatzer vascular plug.