Synthesizing and formulating metal oxide nanoparticle inks for perovskite solar cells.

The perovskite solar cell has commercial potential due to the low-cost of materials and manufacturing processes with cell efficiencies on par with traditional technologies. Nanomaterials have many properties that make them attractive for the perovskite devices, including low-cost inks, low temperature processing, stable material properties and good charge transport. In this feature article, the use of nanomaterials in the hole transport and electron transport layers are reviewed. Specifically, SnO2 and NiOx are the leading materials with the most promise for translation to large scale applications. The review includes a discussion of the synthesis, formulation, and processing of these nanoparticles and provides insights for their further deployment towards commercially viable perovskite solar cells.

Solvation of NiOxfor hole transport layer deposition in perovskite solar cells.

A series of nickel oxide (NiOx) inks, in the perovskite antisolvent chlorobenzene (CB) containing 15% ethanol, were prepared for the fabrication of p-i-n perovskite solar cells by blade coating. The inks included triethylamine (Et3N) and alkyl xanthate salts as ligands to disperse NiOxparticle aggregates and stabilize suspension. A total of four inks were evaluated: 0X (Et3N with no alkyl xanthate), 4X (Et3N + potassiumn-butyl xanthate), 12X (Et3N + potassiumn-dodecyl xanthate), and 18X (Et3N + potassiumn-octadecyl xanthate). The inks were characterized by UV-visible spectroscopy and FT-IR spectroscopy and the resulting films analyzed by thermogravimetry and scanning electron microscopy. Devices prepared using the 0X ink resulted in a peak power conversion efficiency (PCE) of 14.47% (0.25 cm2) and 9.96% (1 cm2). The 0X devices showed no significant loss of PCE after 100 days in a nitrogen flow box. Devices prepared with inks containing alkyl xanthate ligand had lower PCE that decreased with decreasing chain length, 18X > 12X > 4X.

Comparison of Surgisis, AlloDerm, and Vicryl Woven Mesh grafts for abdominal wall defect repair in an animal model.

BACKGROUND: Surgisis and AlloDerm, two biosynthetic materials, have been previously used with success in abdominal wall repairs in the setting of contaminated fields. Historically, Vicryl Woven Mesh, a synthetic material, has also been used in such settings as a temporary bridge for abdominal wall reconstruction. This study compares Surgisis and AlloDerm with Vicryl Woven Mesh with respect to tensile strength, collagen remodeling, and neovascularization using a rat hernia model. METHODS: A prospective randomized trial of 54 Sprague-Dawley rats were assigned to the Surgisis, AlloDerm, or Vicryl Woven Mesh group with baseline, 30-day, and 60-day end points. A 1.5-cm x 5.0-cm defect was created in the right abdominis rectus muscle and repaired with an underlay bridge graft using the different treatment materials. Tensile strength was measured using an Instron tensiometer. Histologic specimens were evaluated for neovascularization, collagen deposition, and collagen organization at the 30- and 60-day time points. RESULTS: Surgisis had significantly greater tensile strength compared to Vicryl Woven Mesh at the baseline time point (0.142 vs. 0.091 MPa, p < 0.05). There were no differences between groups tensile strength at 30 or 60 days postoperatively. The Vicryl Woven Mesh and AlloDerm groups showed increases in tensile strength at 30 days postoperatively versus baseline (p < 0.05). Vicryl Woven Mesh, Surgisis, and AlloDerm all showed increases in tensile strength at 60 days postoperatively compared to 30 days postoperatively and at baseline (p < 0.05). Surgisis and AlloDerm had significantly greater (p < 0.05) amounts of collagen deposition and organization at 30 and 60 days compared to Vicryl Woven Mesh. There was no significant difference between AlloDerm and Surgisis with respect to collagen deposition and organization. Surgisis and AlloDerm showed a significantly greater amount (p < 0.05) of neovascularization than Vicryl Woven Mesh at both time points. In addition, Surgisis had a significantly greater amount (p < 0.05) of neovascularization than AlloDerm at both 30 and 60 days. CONCLUSION: Surgisis has increased baseline tensile strength compared to Vicryl Woven Mesh. Tensile strength in Vicryl Woven Mesh is equal to biosynthetic grafts after tissue incorporation. Biosynthetic grafts showed superior collagen deposition and organization. Surgisis mesh showed increased neovascularization over both AlloDerm and Vicryl Woven Mesh.

Brachial artery fibromuscular dysplasia.

Fibromuscular dysplasia is a rare vascular disease that is characterized as nonatherosclerotic and noninflammatory in nature. This disease most commonly afflicts the renal and cerebrovascular beds but can rarely affect the upper extremity. We present the case of a 76-year-old woman who complained of a symptom complex, congruent with Raynaud's phenomenon on the right side. The patient had evidence of distal ischemia without the classic angiographic evidence of fibromuscular dysplasia on arteriography. The abnormal arterial section of the right brachial artery was resected and grafted with reversed saphenous vein. She has had no reoccurrence of her symptoms and no stenosis of her graft over a 3-year follow-up period.

Permacol (porcine dermal collagen) and Alloderm (acellular cadaveric dermis) as a vascular patch repair for common carotid arteriotomy in a rabbit model.

Occult injuries to arteries are common in trauma and evolution of their repair has been observed throughout military conflicts. Currently, autogenous vein and polytetrafluoroethylene (PTFE) are used as patch agents for arterial trauma. However, suitable vein is often lacking in multitrauma patients, and PTFE is prone to infection in the contaminated combat wound. The purpose of this study is to evaluate Permacol, porcine dermal collagen, and Alloderm, acellular cadaveric dermis, as suitable alternatives to PTFE with the potential benefit of being used in contaminated wounds. A New Zealand White rabbit common carotid arteriotomy model was used to compare Permacol (n = 12), Alloderm (n = 11), and PTFE (n = 13) for patch repair. Thrombin generation was examined using an enzyme-linked immunosorbent assay for thrombin-antithrombin complex. Histological samples were taken to analyze vessel lumen area, vessel diameter, intimal thickness, and medial thickness. Pathological examinations were made to compare rates of intimal hyperplasia, aneurysm, patency, and thrombus formation. The Permacol group showed equivalent rates of thrombus, aneurysm, and patency compared with PTFE. Increased lumen area was seen in the Permacol group, 0.344 mm2 (p = 0.02) compared with the PTFE group, 0.204 mm2. Permacol also had decreased incidence of intimal hyperplasia compared with PTFE, 50.0% versus 92% (p < 0.05). Alloderm had increased rates of aneurysm formation, 63.6% (p = 0.004) compared with PTFE, 0.0%, and Permacol groups, 8.3%. Alloderm also had increased intimal thickness through the patch, 0.076 mm (p = 0.18), compared with PTFE, 0.026 mm, and Permacol groups, 0.024 mm. Vessel diameter through the patch showed the Alloderm group, 1.87 mm (p = 0.004), was significantly larger than both the Permacol, 1.41 mm, and PTFE groups, 1.28 mm. Furthermore, Alloderm showed leukocyte migration around the patch. Enzyme-linked immunosorbent assay for thrombin-antithrombin complex was only elevated for PTFE in the 7-day postoperative measurement but was not statistically different from the other groups. Permacol has characteristics to be an effective alternative for PTFE for patch arteriotomy repair in our rabbit model. Futher studies need to be conducted to investigate the potential of Permacol in vascular trauma. Alloderm is not a suitable alternative to PTFE for patch arteriotomy repair.

Superior mesenteric artery branch aneurysm with absence of the celiac trunk.

Superior mesenteric artery and pancreaticoduodenal artery aneurysms are rare. Agenesis of the celiac axis has only been reported four times. The reported etiologies of superior mesenteric artery and branch artery aneurysms include infection, atherosclerosis, inflammatory processes such as pancreatitis, dissection, collagen vascular disorders, polyarteritis nodosa, and trauma. We report an aneurysm of the superior mesenteric artery (SMA) branch, the inferior pancreaticoduodenal artery, arising in a patient with congenital absence of the celiac trunk. The patient presented with intermittent left upper quadrant pain without weight loss or change in bowel habits. The aneurysm was identified on abdominal computed tomography scan with angiographic confirmation of the aberrant anatomy. The patient was treated by aneurysmectomy and pancreaticoduodenal artery reconstruction with an interposition vein graft from the SMA. The patient recovered without complications and is asymptomatic with a patent vein graft 2 years after operation.

Porcine dermal collagen (Permacol) for abdominal wall reconstruction.

OBJECTIVE: A review of Eisenhower Army Medical Center's experience using Permacol (Tissue Science Laboratories, Covington, Georgia) for the repair of abdominal wall defects. METHODS: Retrospective review of medical records of patients undergoing abdominal wall reconstruction with Permacol. RESULTS: From July 30, 2003 to February 12, 2005, 9 patients underwent repair of complicated fascial defects with Permacol. Indications for surgery included reoperative incisional hernia repair after removal of a infected mesh (3 patients), reconstruction of a fascial defect after resection of an abdominal wall tumor (2 patients), incisional hernia repair in a patient with a previous abdominal wall infection after a primary incisional hernia repair (1 patient), incisional hernia repair in a patient with an ostomy and an open midline wound (1 patient), emergent repair of incisional hernia with strangulated bowel and multiple intra-abdominal abscesses (1 patient), and excision of infected mesh and drainage of intra-abdominal abscess with synchronous repair of the abdominal wall defect (1 patient). At a median follow-up of 18.2 months, 1 recurrent hernia existed after intentional removal of the Permacol. This patient developed an abdominal wall abscess 7 months after hernia repair secondary to erosion from a suture. Overall, 1 patient developed exposure of the Permacol after a skin dehiscence. The wound was treated with local wound care, and the Permacol was salvaged. Despite the presence of contamination (wound classification II, III, or IV) in 5 of 9 patients (56%), no infectious complications occurred. CONCLUSION: Complex reconstruction of the abdominal wall can be associated with a high complication rate. Placement of a permanent prosthetic mesh in a contaminated field is associated with a high rate of wound infections and subsequent mesh removal. Permacol becomes incorporated by tissue ingrowth and neovascularization. Permacol is a safe and acceptable alternative to prosthetic mesh in the repair of complicated abdominal wall defects.

The safety and effectiveness of a modified convection heating system for children during anesthesia.

BACKGROUND: Convection heating shows most promise in maintaining children's core temperatures under anesthesia. We have previously shown that a modified convection heating technique worked in a mannequin model and sought to establish its safety and effectiveness in a clinical study. METHODS: Children were recruited who were having elective surgery under general anesthesia lasting >90 min. The children were anesthetized and maintained in a room temperature of 21 degrees C. Warming was performed by a 'Bair Hugger' attached to a heat dissipation box, producing turbulent air from multiple outlet holes on its face. A plastic sheet covered the child, was attached to the top of the box, tucked into the sides of the bed and left open at the head end. Temperatures at various sites (air, skin, and core) were continuously monitored using thermistors connected to a datalogger and laptop. Analysis was performed using Excel. RESULTS: The study comprised 40 children ranging in age from 2 days to 12.5 years and weigh 2.5-73 kg. Operations were 'peripheral' (e.g. urethroplasty) lasting 90 min to major laparotomy lasting 590 min. Body surface area uncovered was 5-25%. Skin temperatures rose to a maximum of c. 40 degrees C. Core temperatures rose after a 12-min lag by 0.01-0.04 degrees C x min(-1). In children who became hyperthermic, cooling was readily achieved by turning the heating off and leaving the fan running. CONCLUSIONS: The technique is safe and effective for children throughout the pediatric range. The practice of increasing room temperature above 21 degrees C for elective cases should be abandoned. Continuous monitoring of core temperature is necessary to prevent hyperthermia.

Suppression of experimental aortic aneurysms: comparison of inducible nitric oxide synthase and cyclooxygenase inhibitors.

The rat model of abdominal aortic aneurysm (AAA) is associated with inflammation, destruction of extracellular matrix, and production of both inducible nitric oxide synthase (iNOS) and matrix metalloproteinase-9 (MMP-9). Indomethacin, a nonselective cyclooxygenase inhibitor, may prevent AAA formation by inhibiting cyclooxygenase-2 (COX-2) activity. We hypothesized that indomethacin, rofecoxib (selective COX-2 inhibitor), and 1400 W (selective iNOS activity inhibitor) would decrease aneurysm formation in the rat model. Forty-six male Wistar rats underwent intraaortic elastase infusion in two parallel studies based on medication delivery route. Sixteen rats were randomized to rofecoxib or water by gastric lavage. Thirty rats were randomized to subcutaneous saline, indomethacin, or 1400 W. Heart rate, blood pressure and aortic diameters were measured. Western Blot and mRNA analysis for MMP-9 and iNOS was performed on postoperative day 7 aortic segments. Elastin degradation and inflammation were evaluated by immunohistochemistry. Elastase infusion produced AAA in all rats. 1400 W significantly limited aneurysm expansion (p = 0.01) whereas treatment with indomethacin and rofecoxib did not. Only 1400 W significantly increased blood pressure (p < 0.001). Indomethacin alone statistically decreased MMP-9 (p < 0.011). 1400 W resulted in greater conservation of aortic elastin than indomethacin (p = 0.025). All groups demonstrated statistically similar expression of iNOS. In conclusion, selective iNOS activity inhibitor, 1400 W, significantly decreased aneurysm size and preserved aortic elastin without altering MMP-9 levels. Indomethacin significantly decreased MMP-9 expression without decreasing aneurysm size. Rofecoxib did not significantly decrease MMP-9 expression or aneurysm size. Inhibition of iNOS limits aneurysmal expansion by mechanisms other than MMP-9 inhibition. MMP-9 inhibition by indomethacin is not sufficient to limit aneurysm expansion in our model.

Complication rates of percutaneous brachial artery access in peripheral vascular angiography.

The brachial artery has been considered a secondary choice for percutaneous access due to reported increased complication rates compared to femoral access despite potential advantages in peripheral vascular disease (PVD) patients. A prospectively collected database of 1326 PVD patients undergoing angiography with percutaneous brachial access between January 1, 1990 and December 31, 1999 was retrospectively reviewed. All patient charts with coded brachial pathology during this time period were reviewed to ensure complete data capture. The protocol for patients undergoing brachial access included a vascular surgery evaluation after each angiogram and telephone follow-up by a nurse at 24 hr. During this 10-year period, a percutaneous brachial artery approach was used to perform 1084 angiograms in men and 242 angiograms in women. A subset of 111 patients had multiple studies (range: 2 to 7) via brachial access without complication. Rates of failed access (2.1% female vs. 0% male, p <0.001) and brachial thrombosis (1.24% female vs. 0.28% male, p <0.04) were significantly higher in women. The complication rate for all patients was 1.28%. Percutaneous brachial access for angiography can be safely and repetitively performed in PVD patients, although women have an increased risk of thrombosis and failed access. The brachial approach allows early ambulation and discharge, and can be considered a primary choice for diagnostic angiographic access.

Pararenal vena cava leiomyosarcoma versus leiomyomatosis: difficult diagnosis.

Inferior vena cava (IVC) leiomyosarcoma is a rare cancer treated with wide surgical resection. IVC leiomyomatosis is a benign tumor treated with open caval excision. A patient with an IVC tumor with iliocaval thrombosis was treated with thrombolysis and iliac stents. The patient was sent 1 year later to our institution with an IVC mass. Transvenous biopsy was consistent with leiomyomatosis. At surgery, the lesion was adherent, resected and the IVC reconstructed. Pathologic evaluation documented well-differentiated leiomyosarcoma not leiomyomatosis. Thorough evaluation of iliocaval thrombosis is recommended before endovascular management. Diagnostic modalities may be inadequate to differentiate leiomyosarcoma from leiomyomatosis.

Nitric oxide in experimental aneurysm formation: early events and consequences of nitric oxide inhibition.

Mounting evidence suggests that nitric oxide (NO) plays an important role in aneurysm pathogenesis. Nitric oxide synthase (NOS) expression, hemodynamic consequences of NO inhibition, and the effect of NO on matrix metalloproteinase (MMP) expression during aneurysm formation are unknown. In this study, a standard intraaortic elastase infusion rat model was used. Control animals received intraaortic elastase infusion and intraperitoneal saline injections. Experimental groups received intraaortic elastase infusion and intraperitoneal injections of aminoguanidine (500 mg/kg) or L-NAME (2 mg/kg or 10 mg/kg). Aortic diameter, blood pressure, and NO metabolites were measured at surgery and postoperative (POD) 7. A second series of rats were randomly infused with intraaortic elastase or saline and aortas were analyzed on POD 1, 3, and 7 with Western blotting for iNOS, eNOS, and MMP-9 expression. Infusion of elastase produced aneurysms (p > 0.0001) in all rats. Inhibition of NO with aminoguanidine or L-NAME limited aneurysm expansion in all groups (p > 0.05). Nitric oxide metabolites were increased (p < 0.003) in control rats on POD 7. Arterial hypertension was present in all treated animals (p < 0.05). Early up-regulation on POD 1 of iNOS (p < 0.003) was noted in elastas-infused animals, but there was no iNOS expression with saline infusion. MMP-9 expression was present in both groups, with a significant increase in expression for elastase-infused animals noted on POD 7. iNOS expression is up-regulated early in experimental aneurysm formation, followed by increases in MMP-9 expression. Inhibition of NO limits aneurysmal expansion despite production of arterial hypertension.

Differential gene expression in human abdominal aorta: aneurysmal versus occlusive disease.

OBJECTIVE: Inflammation and atherosclerosis are present in both abdominal aortic aneurysm (AAA) and arterial occlusive disease (AOD). Changes in gene expression that underlie the development of AAA versus AOD are poorly defined. This study evaluated differences in gene expression in AAA, AOD, and control aortic tissue with human gene array technology. METHODS: RNA was isolated from human aortic specimens (seven AAA, five AOD, and five control), and complementary DNA (cDNA) probes were generated. The cDNA probes were hybridized to a human cell interaction array of 265 genes and quantitated with phosphorimaging. The data were corrected for background and were standardized to housekeeping genes. Statistical differences in individual gene expression were determined with the Kruskal-Wallis test. RESULTS: Of 265 genes studied, 11 showed statistically different expression in diseased aorta as compared with control. The following three genes were downregulated in AAA: collagen VI alpha1 (P <.037), glycoprotein IIIA (P <.006), and alpha2-macroglobulin (P <.020). The following two genes were upregulated in AOD: laminin alpha4 (P <.034) and insulin-like growth factor 2 receptor (P <.049). The following three genes were upregulated in both AAA and AOD: matrix metalloproteinase-9 (MMP-9; P <.005), intercellular adhesion molecule-1 (P <.012), and tumor necrosis factor--beta receptor (P <.022). The following three genes were downregulated in both AAA and AOD: integrin alpha5 (P <.012), ephrin A5 (P <.037), and rho/rac guanine nucleotide exchange factor (P <.028). Of 16 MMPs evaluated, only MMP-9 was significantly (P <.005) upregulated in both AAA and AOD. Evaluation results of four tissue inhibitors of metalloproteinases showed no significant difference in expression for all tissue types, although tissue inhibitor of metalloproteinase-1 trended toward upregulation in AAA (P =.053). Eight of the fifteen most highly expressed genes in all the groups were extracellular matrix or secreted proteins. Of these, only collagen VI alpha1 (P <.037) showed a significant change, although biglycan trended toward downregulation in AAA (P =.076). CONCLUSION: This study used cDNA array technology in the comparison of human control and pathologic aortic tissue. Six genes had similar differential expression in both AAA and AOD as compared with control. Even more interesting were differences between AAA and AOD in the expression of five genes. These data suggest a similarity in genetic expression for both AAA and AOD, with altered expression of several genes playing a role in disease differentiation.

The influence of drug polarity on the absorption of opioid drugs into CSF and subsequent cephalad migration following lumbar epidural administration: application to morphine and pethidine.

This study examines the influence of drug polarity on the rate and extent of drug absorption into cerebrospinal fluid (CSF) following lumbar epidural administration. Twelve patients with pain secondary to cancer were simultaneously administered both morphine (10 mg) and pethidine (50 mg) in 10 ml of normal saline via an epidural catheter inserted in the lumbar region (usually L2,3) and attached to a subcutaneously implanted portal reservoir. Frequent blood samples were collected to characterise the vascular uptake of both opioids. In addition, a single CSF sample was collected in each patient from the C7-T1 interspace at one of the following times: 10, 30, 60, 120, 180 and 240 min. There was a rapid vascular uptake of morphine from the epidural space with a mean (+/- S.D.) peak concentration of 173 +/- 80 ng/ml (range 52-345 ng/ml) and a time-to-peak concentration of 8 +/- 6 min (range 2-17 min). In contrast, the vascular uptake of pethidine was more variable with a mean (+/- S.D.) concentration of 274 +/- 294 ng/ml (range 80-1113 ng/ml) and the time-to-peak concentration was 21 +/- 26 min (range 2-75 min). There was a rapid absorption of pethidine across the dura mater into the CSF with peak CSF concentrations between 1400 and 1650 ng/ml occurring between 10 and 60 min in samples collected cephalad (C7-T1 interspace) from the administration point in the lumbar region. However, the peak morphine concentration in CSF was delayed relative to the pethidine peak and occurred at 120 min.(ABSTRACT TRUNCATED AT 250 WORDS)