Supported Platinum Nanoparticles Catalyzed Carbon-Carbon Bond Cleavage of Polyolefins: Role of the Oxide Support Acidity.

Supported platinum nanoparticle catalysts are known to convert polyolefins to high-quality liquid hydrocarbons using hydrogen under relatively mild conditions. To date, few studies using platinum grafted onto various metal oxide (MxOy) supports have been undertaken to understand the role of the acidity of the oxide support in the carbon-carbon bond cleavage of polyethylene under consistent catalytic conditions. Specifically, two Pt/MxOy catalysts (MxOy = SrTiO3 and SiO2-Al2O3; Al = 3.0 wt %, target Pt loading 2 wt % Pt ∼1.5 nm), under identical catalytic polyethylene hydrogenolysis conditions (T = 300 °C, P(H2) = 170 psi, t = 24 h; Mw = ∼3,800 g/mol, Mn = ∼1,100 g/mol, D = 3.45, Nbranch/100C = 1.0), yielded a narrow distribution of hydrocarbons with molecular weights in the range of lubricants (Mw = < 600 g/mol; Mn < 400 g/mol; D = 1.5). While Pt/SrTiO3 formed saturated hydrocarbons with negligible branching, Pt/SiO2-Al2O3 formed partially unsaturated hydrocarbons (<1 mol % alkenes and ∼4 mol % alkyl aromatics) with increased branch density (Nbranch/100C = 5.5). Further investigations suggest evidence for a competitive hydrocracking mechanism occurring alongside hydrogenolysis, stemming from the increased acidity of Pt/SiO2-Al2O3 compared to Pt/SrTiO3. Additionally, the products of these polymer deconstruction reactions were found to be independent of the polyethylene feedstock, allowing the potential to upcycle polyethylenes with various properties into a value-added product.

Scalable Synthesis of Pt/SrTiO3 Hydrogenolysis Catalysts in Pursuit of Manufacturing-Relevant Waste Plastic Solutions.

An improved hydrothermal synthesis of shape-controlled, size-controlled 60 nm SrTiO3 nanocuboid (STO NC) supports, which facilitates the scalable creation of platinum nanoparticle catalysts supported on STO (Pt/STO) for the chemical conversion of waste polyolefins, is reported herein. This synthetic method (1) establishes that STO nucleation prior to the hydrothermal treatment favors nanocuboid formation, (2) produces STO NC supports with average sizes ranging from 25 to 80 nm with narrow size distributions, and (3) demonstrates how SrCO3 formation and variation in solution pH prevent the formation of STO NCs. The STO synthesis was scaled-up and conducted in a 4 L batch reactor, resulting in STO NCs of comparable size and morphology (m = 22.5 g, davg = 58.6 ± 16.2 nm) to those synthesized under standard hydrothermal conditions in a lab-scale 125 mL autoclave reactor. Size-controlled STO NCs, ranging in roughly 10 nm increments from 25 to 80 nm, were used to support Pt deposited through strong electrostatic adsorption (SEA), a practical and scalable solution-based method. Using SEA techniques and an STO support with an average size of 39.3 ± 6.3 nm, a Pt/STO catalyst with 3.6 wt % Pt was produced and used for high-density polyethylene hydrogenolysis under previously reported conditions (170 psi H2, 300 °C, 96 h; final product: Mw = 2400, D = 1.03). As a well-established model system for studying the behavior of heterogeneous catalysts and their supports, the Pt/STO system detailed in this work presents a unique opportunity to simultaneously convert waste plastic into commercially viable products while gaining insight into how scalable inorganic synthesis can support transformative manufacturing.

Assessing the Single and Combined Toxicity of the Bioinsecticide Spear and Cry3Bb1 Protein Against Susceptible and Resistant Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae).

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), poses a serious threat to maize (Zea mays L.) growers in the U.S. Corn Belt. Transgenic corn expressing Bacillus thuringiensis (Bt) Berliner is the major management tactic along with crop rotation. Bt crops targeting WCR populations have been widely planted throughout the Corn Belt. Rootworms have developed resistance to nearly all management strategies including Bt corn. Therefore, there is a need for new products that are not cross-resistant with the current Bt proteins. In this study, we evaluated the susceptibility of WCR strains resistant and susceptible to Cry3Bb1 to the biological insecticide Spear-T (GS-omega/kappa-Hexatoxin-Hv1a) alone and combined with Cry3Bb1 protein. The activity of Hv1a alone was similar between Cry3Bb1-resistant and susceptible strains (LC50s = 0.95 mg/cm2 and 1.50 mg/cm2, respectively), suggesting that there is no cross-resistance with Cry3Bb1 protein. Effective concentration (EC50), molt inhibition concentration (MIC50), and inhibition concentration (IC50) values of Hv1a alone were also similar between both strains, based on non-overlapping confidence intervals. Increased mortality (64%) was observed on resistant larvae exposed to Hv1a (0.6 mg/cm2) + Cry3Bb1 protein (170.8 µg/cm2) compared to 0% mortality when exposed to Cry3Bb1 alone and 34% mortality to Hv1a alone (0.3 mg/cm2). The time of larval death was not significantly different between Hv1a alone (3.79 mg/cm2) and Hv1a (0.6 mg/cm2) + Cry3Bb1 (170.8 µg/cm2). New control strategies that are not cross-resistant with current insecticides and Bt proteins are needed to better manage the WCR, and Hv1a together with Cry3Bb1 may fit this role.

Synthetic Lubricants Derived from Plastic Waste and their Tribological Performance.

The energy efficiency, mechanical durability, and environmental compatibility of all moving machine components rely heavily on advanced lubricants for smooth and safe operation. Herein an alternative family of high-quality liquid (HQL) lubricants was derived by the catalytic conversion of pre- and post-consumer polyolefin waste. The plastic-derived lubricants performed comparably to synthetic base oils such as polyalphaolefins (PAOs), both with a wear scar volume (WSV) of 7.5×10-5  mm-3 . HQLs also performed superior to petroleum-based lubricants such as Group III mineral oil with a WSV of 1.7×10-4  mm-3 , showcasing a 44 % reduction in wear. Furthermore, a synergistic reduction in friction and wear was observed when combining the upcycled plastic lubricant with synthetic oils. Life cycle and techno-economic analyses also showed this process to be energetically efficient and economically feasible. This novel technology offers a cost-effective opportunity to reduce the harmful environmental impact of plastic waste on our planet and to save energy through reduction of friction and wear-related degradations in transportation applications akin to synthetic oils.

Rapid Administration of Ketamine for Abscess Drainage in Children-A Dose Finding Study.

STUDY OBJECTIVE: To estimate the minimum dose and total sedation time of rapidly infused ketamine that achieves 3 to 5 minutes of effective sedation in children undergoing abscess incision and drainage in the emergency department. METHODS: The Up-Down method was used to estimate the dose of intravenous ketamine infused over 5 seconds or less that provided effective sedation in 50% (ED50) and 95% (ED95) for healthy children aged 2 to 5 years and 6 to 11 years undergoing abscess incision and drainage. None were pretreated with opioids. Three investigators blinded to ketamine dose independently graded sedation effectiveness by viewing a video recording of the first 5 minutes of sedation. Recovery was determined when patients reached a Modified Aldrete score of 10. RESULTS: We enrolled 20 children in each age group. The estimated ED50 was 0.9 and 0.6 mg/kg for the 2 to 5 years and 6 to 11 years' groups and the estimated ED95 was 1.1 mg/kg for both groups. The median time to full recovery for the 2 groups was 20.5 and 17.5 minutes when only 1 dose of ketamine was administered and 27.5 and 35 minutes when additional doses of ketamine were administered. No participants experienced serious adverse events. CONCLUSIONS: We estimated ED50 and ED95 for rapidly infused ketamine for 2 age groups undergoing abscess incision and drainage. Further studies are needed to get a more precise estimate of ED95. The total sedation time with this technique in the abscess group was shorter than most previous studies and is consistent with our previous observations in patients undergoing fracture reduction.

Upcycling Single-Use Polyethylene into High-Quality Liquid Products.

Our civilization relies on synthetic polymers for all aspects of modern life; yet, inefficient recycling and extremely slow environmental degradation of plastics are causing increasing concern about their widespread use. After a single use, many of these materials are currently treated as waste, underutilizing their inherent chemical and energy value. In this study, energy-rich polyethylene (PE) macromolecules are catalytically transformed into value-added products by hydrogenolysis using well-dispersed Pt nanoparticles (NPs) supported on SrTiO3 perovskite nanocuboids by atomic layer deposition. Pt/SrTiO3 completely converts PE (M n = 8000-158,000 Da) or a single-use plastic bag (M n = 31,000 Da) into high-quality liquid products, such as lubricants and waxes, characterized by a narrow distribution of oligomeric chains, at 170 psi H2 and 300 °C under solvent-free conditions for reaction durations up to 96 h. The binding of PE onto the catalyst surface contributes to the number averaged molecular weight (M n) and the narrow polydispersity (D) of the final liquid product. Solid-state nuclear magnetic resonance of 13C-enriched PE adsorption studies and density functional theory computations suggest that PE adsorption is more favorable on Pt sites than that on the SrTiO3 support. Smaller Pt NPs with higher concentrations of undercoordinated Pt sites over-hydrogenolyzed PE to undesired light hydrocarbons.

Complex surface structure of (110) terminated strontium titanate nanododecahedra.

The surface structure of (110) faceted strontium titanate nanoparticles synthesized via solvothermal method has been resolved using high-resolution electron microscopy (HREM). We demonstrate that the surface is a titania-rich structure containing tetrahedrally coordinated TiO4 units similar to the family of (n × 1) reconstructions observed on (110) surfaces of bulk crystalline strontium titanate. When compared with prior results for (001) terminated strontium titanate single crystals made with traditional transmission electron microscopy (TEM) sample preparation techniques, the results demonstrate that many models for oxide nanoparticles need to be revisited. This work serves as a reminder that attention must be paid to the surface of nanoparticles. Even with a simple perovskite as the starting point the end result can be very complex. As more materials are synthesized on the nanoscale, this will become increasingly important to take into consideration.

Update on pharmacological management of procedural sedation for children.

PURPOSE OF REVIEW: The review provides an update on pharmacological techniques for procedural sedation for children outside the operating room. RECENT FINDINGS: An increasing number of studies of propofol, ketamine, nitrous oxide, dexmedetomidine, and intranasal administration of drugs for procedural sedation of children continue to be reported. SUMMARY: Propofol and ketamine are commonly used for procedural sedation in children and the use of dexmedetomidine and nitrous oxide is increasing. Although the intravenous route remains the mainstay; intranasal drug administration is increasingly used for anxiolysis and moderate sedation.

Rapid administration technique of ketamine for pediatric forearm fracture reduction: a dose-finding study.

STUDY OBJECTIVE: We estimate the minimum dose and total sedation time of rapidly infused ketamine that achieves 3 to 5 minutes of effective sedation in children undergoing forearm fracture reduction in the emergency department. METHODS: We used the up-down method to estimate the median dose of intravenous ketamine infused during less than or equal to 5 seconds that provided effective sedation in 50% (ED50) and 95% (ED95) of healthy children aged 2 to 5, 6 to 11, or 12 to 17 years who were undergoing forearm fracture reduction. Most patients were pretreated with opioids. Three investigators blinded to ketamine dose independently graded sedation effectiveness by viewing a video recording of the first 5 minutes of sedation. Recovery was assessed by modified Aldrete score. RESULTS: We enrolled 20 children in each age group. The estimated ED50 was 0.7, 0.5, and 0.6 mg/kg and the estimated ED95 was 0.7, 0.7, and 0.8 mg/kg for the groups aged 2 to 5, 6 to 11, and 12 to 17 years, respectively. For the group aged 2 to 5 years, an empirically derived ED95 was 0.8 mg/kg. All patients who received the empirically derived ED95 in the group aged 2 to 5 years or the estimated ED95 in the groups aged 6 to 11 and 12 to 17 years had effective sedation. The median total sedation time for the 3 age groups, respectively, was 25, 22.5, and 25 minutes if 1 dose of ketamine was administered and 35, 25, and 45 minutes if additional doses were administered. No participant experienced serious adverse events. CONCLUSION: We estimated ED50 and ED95 for rapidly infused ketamine for 3 age groups undergoing fracture reduction. Total sedation time was shorter than that in most previous studies.

The role of oleic acid: from synthesis to assembly of perovskite nanocuboid two-dimensional arrays.

Oleic acid, an 18-carbon chain fatty acid, has been widely used as a surfactant to fabricate colloidal nanocrystals. In previous work, we discovered a lamellar microemulsion strategy to fabricate sub-20 nm SrTiO(3) nanocuboids using oleic acid and oleate species. Here, we demonstrate (i) the general synthesis with lamellar microemulsions of a family of compositionally varied BaxSr(1-x)TiO(3) crystalline nanocuboids with uniform size, and (ii) subsequent assembly into two-dimensional arrays by nanoparticle-bound oleate in a nonpolar solvent. The measured interparticle distance (2.4 nm) of adjacent nanoparticles in an array is less than the length of a double oleate layer (∼4 nm). On the basis of calculations of the interfacial free energy, we propose the hydrophobic, hydrocarbon-terminated groups of oleate from adjacent nanocuboids are situated closely but do not overlap. Lower aspect ratio nanocuboids are bordered by four adjacent nanocuboids which results in a uniform direction self-assembly array, whereas higher aspect ratio nanocuboids are bordered by five or six adjacent nanocuboids and can develop an arced local coordination.

Synthesis-dependent atomic surface structures of oxide nanoparticles.

Using SrTiO3 nanocuboids as a model system, we show with aberration-corrected high resolution electron microscopy at sub-Å resolution that surface relaxations or reconstructions are present on the nanocuboids, depending on the synthetic process. Oleic acid synthesis, acetic acid synthesis, and microwave-assisted acetic acid synthesis result in a SrO termination, TiO2-rich reconstruction, and mixed termination, respectively. The experimental atomic positions are in better agreement with density functional theory calculations using an exact-exchange corrected PBEsol functional than the Perdew-Burke-Ernzerhof (PBE) functional.

Clinical practice guideline for emergency department ketamine dissociative sedation: 2011 update.

We update an evidence-based clinical practice guideline for the administration of the dissociative agent ketamine for emergency department procedural sedation and analgesia. Substantial new research warrants revision of the widely disseminated 2004 guideline, particularly with respect to contraindications, age recommendations, potential neurotoxicity, and the role of coadministered anticholinergics and benzodiazepines. We critically discuss indications, contraindications, personnel requirements, monitoring, dosing, coadministered medications, recovery issues, and future research questions for ketamine dissociative sedation.

Frequency and importance of small amount of isolated pelvic free fluid detected with multidetector CT in male patients with blunt trauma.

PURPOSE: To retrospectively determine the frequency and importance of a small amount of isolated pelvic free fluid seen at multidetector computed tomography (CT) in male patients who have blunt trauma without an identifiable cause. MATERIALS AND METHODS: Institutional review board approval was obtained, and the requirement for informed consent was waived for this HIPAA-compliant study. One thousand male patients with blunt trauma who underwent abdominopelvic CT at a level 1 trauma center between January 2004 and June 2006 were entered into this study. The CT images of the 1000 patients were reviewed independently by two abdominal radiologists. CT scan assessment included evaluation for presence or absence of pelvic free fluid, any traumatic or nontraumatic cause of the free fluid, pelvic free fluid attenuation and volume measurements, and determination of the location of pelvic free fluid. Interobserver agreement was determined with kappa statistics, and the Student t test was used to assess differences in the mean volume and mean attenuation of the pelvic free fluid in the patients with and those without injury. RESULTS: Pelvic free fluid was identified in 10.2% (102 of 1000) of patients. A small amount of isolated pelvic free fluid without any identifiable cause was identified in 4.8% (48 of 1000) of patients by reader 1 and in 5.0% (50 of 1000) of patients by reader 2 (kappa value, 0.76) and was located at or below the level of the third sacral vertebral body in all 49 patients with isolated pelvic free fluid. The mean volume and mean attenuation of the small amount of isolated pelvic free fluid were 2.3 mL +/- 1.5 (standard deviation) and 8.1 HU +/- 3.9, respectively. None of the patients in this group had an undiagnosed bowel and/or mesenteric injury. CONCLUSION: In male patients with blunt trauma, a small amount of isolated pelvic free fluid with attenuation equal to that of simple fluid and located in the deep region of the pelvis likely is not a sign of bowel and/or mesenteric injury.

Consensus-based recommendations for standardizing terminology and reporting adverse events for emergency department procedural sedation and analgesia in children.

Children commonly require sedation and analgesia for procedures in the emergency department. Establishing accurate adverse event and complications rates from the available literature has been difficult because of the difficulty in aggregating results from previous studies that have used varied terminology to describe the same adverse events and outcomes. Further, serious adverse events occur infrequently, necessitating the study of large numbers of children to assess safety. These limitations prevent the establishment of a sufficiently large database on which evidence-based practice guidelines may be based. We assembled a panel of pediatric sedation researchers and experts to develop consensus-based recommendations for standardizing procedural sedation and analgesia terminology and reporting of adverse events. Our goal was to create a uniform reporting mechanism for future studies to facilitate the aggregation and comparison of results.

Clinical implications of unmanaged needle-insertion pain and distress in children.

Increasing evidence has demonstrated that pain from venipuncture and intravenous cannulation is an important source of pediatric pain and has a lasting impact. Ascending sensory neural pain pathways are functioning in preterm and term infants, yet descending inhibitory pathways seem to mature postnatally. Consequently, infants may experience pain from the same stimulus more intensely than older children. In addition, painful perinatal procedures such as heel lancing or circumcision have been found to correlate with stronger negative responses to venipuncture and intramuscular vaccinations weeks to months later. Similarly, older children have reported greater pain during follow-up cancer-related procedures if the pain of the initial procedure was poorly controlled, despite improved analgesia during the subsequent procedures. Fortunately, both pharmacologic and nonpharmacologic techniques have been found to reduce children's acute pain and distress and subsequent negative behaviors during venipuncture and intravenous catheter insertion. This review summarizes the evidence for the importance of managing pediatric procedural pain and methods for reducing venous access pain.

On the front lines: lessons learned in implementing multidisciplinary peripheral venous access pain-management programs in pediatric hospitals.

Venipuncture and intravenous cannulation are among the most common and widespread medical procedures performed on children today. Therefore, effective treatment of venous access pain can benefit from an integrated systems approach that enlists multiple players in the health care system. By using case studies that analyze this issue from the perspective of the nurse, the physician, the pharmacist, and the child life specialist, this article illustrates how multidisciplinary programs designed to manage needle pain have been developed successfully in several institutions. Common themes that arise from these case studies include the importance of a multidisciplinary evidence-based approach to advocate change; a system-wide protocol for the administration of local anesthetics; convenient access to topical local anesthetics; department and hospital-wide support for educational efforts, including training in nonpharmacologic techniques used by child life specialists; and ongoing quantification of the overall success of any program. Implementation of these strategies can result in significant improvements in the pediatric venous access experience.

The discovery of the benzhydroxamate MEK inhibitors CI-1040 and PD 0325901.

A novel series of benzhydroxamate esters derived from their precursor anthranilic acids have been prepared and have been identified as potent MEK inhibitors. 2-(2-Chloro-4-iodo-phenylamino)-N-cyclopropylmethoxy-3,4-difluoro-benzamide, CI-1040, was the first MEK inhibitor to demonstrate in vivo activity in preclinical animal models and subsequently became the first MEK inhibitor to enter clinical trial. CI-1040 suffered however from poor exposure due to its poor solubility and rapid clearance, and as a result, development of the compound was terminated. Optimization of the diphenylamine core and modification of the hydroxamate side chain for cell potency, solubility, and exposure with oral delivery resulted in the discovery of the clinical candidate N-(2,3-dihydroxy-propoxy)-3,4-difluoro-2-(2-fluoro-4-iodo-phenylamino)-benzamide PD 0325901.

Oxycodone versus codeine for triage pain in children with suspected forearm fracture: a randomized controlled trial.

OBJECTIVE: To compare the efficacy of pain reduction of triage oxycodone (O) versus codeine (C) to children with suspected forearm fractures. DESIGN/METHODS: Children, aged 4 to 17 years, were randomized to receive O (0.2 mg/kg; maximum, 15 mg) or C (2 mg/kg; maximum, 120 mg) if isolated forearm fracture was suspected by the emergency department (ED) triage nurse. All other ED staff were blinded to the assignment. The primary outcome measure was a 5-point facial scale (0 = no pain, 4 = severe) completed by subjects to assess pain at baseline then at 30-minute intervals until ED discharge or procedural sedation for fractures requiring reduction. Ten adverse effects were assessed at baseline and the succeeding intervals. Identification of the most painful part of the visit was assessed at discharge. Efficacy and adverse effects of O versus C were compared using generalized estimate equation modeling. RESULTS: One hundred seven subjects (mean age, 10.4 years; African American, 55%; males, 56%) were randomized to O (n = 51) or C (n= 56). Subjects taking O reported a pain score significantly lower than subjects taking C (0.4 faces, P = 0.01). Minor adverse effects occurred in both groups, but itching occurred less in O subjects (odds ratio, 0.37; 95% confidence interval, 0.14-0.99). The most painful part of the visit was radiography (O = 41%, C = 38%) followed by extremity examination (O = 16%, C = 13%) then casting (O = 8%, C = 13%). CONCLUSIONS: Triage-administered O tended toward greater pain reduction compared with C in children with suspected forearm fractures. Although minor adverse effects occurred in both groups, itching occurred more in C. Identification of radiography as the most painful part of fracture evaluation underscores the need for early triage administration of analgesia for suspected fractures.

Thermodynamic and structure guided design of statin based inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

Clinical studies have demonstrated that statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) inhibitors, are effective at lowering mortality levels associated with cardiovascular disease; however, 2-7% of patients may experience statin-induced myalgia that limits compliance with a treatment regimen. High resolution crystal structures, thermodynamic binding parameters, and biochemical data were used to design statin inhibitors with improved HMGR affinity and therapeutic index relative to statin-induced myalgia. These studies facilitated the identification of imidazole 1 as a potent (IC 50 = 7.9 nM) inhibitor with excellent hepatoselectivity (>1000-fold) and good in vivo efficacy. The binding of 1 to HMGR was found to be enthalpically driven with a Delta H of -17.7 kcal/M. Additionally, a second novel series of bicyclic pyrrole-based inhibitors was identified that induced order in a protein flap of HMGR. Similar ordering was detected in a substrate complex, but has not been reported in previous statin inhibitor complexes with HMGR.