The structure of solvent molecules within zeolite pores influences the rates and selectivities of catalytic reactions by altering the free energies of reactive species. Here, we examine the consequences of these effects on the kinetics and thermodynamics of 1,2-epoxybutane (CHO) ring-opening with methanol (CHOH) in acetonitrile (CHCN) cosolvent over Lewis acidic (Zr-BEA) and Brønsted acidic (Al-BEA) zeolites of varying (SiOH) density. Despite ostensibly identical reaction mechanisms across materials, turnover rates depend differently on (SiOH) density between acid types.
View Article and Find Full Text PDFVapor-phase propylene (CH) epoxidation kinetics with hydrogen peroxide (HO) strongly reflects the physical properties of Ti-incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady-state turnover rates of CH epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CHCN) molecules nearby active sites, under identical reaction mechanisms sharing activated HO intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring-opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following CH epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CHCN.
View Article and Find Full Text PDFSolvent molecules alter the free energies of liquid phase species and adsorbed intermediates during catalytic reactions, thereby impacting rates and selectivities. Here, we examine these effects through the epoxidation of 1-hexene (CH) with hydrogen peroxide (HO) over hydrophilic and hydrophobic Ti-BEA zeolites immersed in aqueous solvent mixtures (acetonitrile, methanol, and γ-butyrolactone). Greater HO mole fractions provide greater epoxidation rates, lower HO decomposition rates, and hence improved HO selectivities to the desired epoxide product in each combination of solvent and zeolite.
View Article and Find Full Text PDFAm J Med Genet C Semin Med Genet
June 2022
Newborn screening (NBS) for severe combined immunodeficiency (SCID) utilizing T-cell receptor excision circles (TRECs) has been implemented in all 50 states as of December 2018 and has been transformative for the clinical care of SCID patients. Though having high sensitivity for SCID, NBS-SCID has low specificity, therefore is able to detect other causes of lymphopenia in newborns including many inborn errors of immunity (IEIs). In a recent study, three of six newborns later diagnosed with Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) syndrome were found to have a low TRECs and lymphopenia at birth.
View Article and Find Full Text PDFSolvent molecules interact with reactive species and alter the rates and selectivities of catalytic reactions by orders of magnitude. Specifically, solvent molecules can modify the free energies of liquid phase and surface species solvation, participating directly as a reactant or co-catalyst, or competitively binding to active sites. These effects carry consequences for reactions relevant for the conversion of renewable or recyclable feedstocks, the development of distributed chemical manufacturing, and the utilization of renewable energy to drive chemical reactions.
View Article and Find Full Text PDFGut-innervating nociceptor sensory neurons respond to noxious stimuli by initiating protective responses including pain and inflammation; however, their role in enteric infections is unclear. Here, we find that nociceptor neurons critically mediate host defense against the bacterial pathogen Salmonella enterica serovar Typhimurium (STm). Dorsal root ganglia nociceptors protect against STm colonization, invasion, and dissemination from the gut.
View Article and Find Full Text PDFCompounds that contribute to the somatosensory flavor profile of bovine fluid milk products were investigated. Sensory descriptive analysis defined five main attributes that consisted of "mouthcoating, astringent/drying, fatty texture, dairy mouthfeel, and tingling/irritation" sensations. Utilizing multi-dimensional LC sensory guided fractionation, compounds with these attributes were selected, purified and subsequently identified by LC/MS as orotic acid, pantothenic acid, hippuric acid, and p-cresol sulfate.
View Article and Find Full Text PDFSpontaneous oxidized flavor (SOF) has been reported over the past 5 decades as a sporadic objectionable flavor problem in bovine milk. Parameters previously reported to influence SOF development in milk have been contradictory, limiting the ability to monitor and develop mitigation strategies. The current paper investigates the causative compounds associated with milk identified as SOF milk in the Midwest dairy region of the United States.
View Article and Find Full Text PDFSoil liquefaction has been extensively investigated over the years with the aim to understand its fundamental mechanism and successfully remediate it. Despite the multi-directional nature of earthquakes, the vertical seismic component is largely neglected, as it is traditionally considered to be of much lower amplitude than the components in the horizontal plane. The 2010-2011 Canterbury earthquake sequence in New Zealand is a prime example that vertical accelerations can be of significant magnitude, with peak amplitudes well exceeding their horizontal counterparts.
View Article and Find Full Text PDFMedicine (Baltimore)
September 2015
A public health approach to combination HIV prevention is advocated to contain the epidemic in sub-Saharan Africa. We explore the implications of universal access to treatment along with HIV education scale-up in the region. We develop an HIV transmission model to investigate the impacts of universal access to treatment, as well as an analytical framework to estimate the effects of HIV education scale-up on the epidemic.
View Article and Find Full Text PDFOptimization of N removal in soil-based wastewater treatment systems requires an understanding of the microbial processes involved in N transformations. We examined the fate of NH in intermittently aerated leachfield mesocosms over a 24-h period. Septic tank effluent (STE) was amended with NHCl to help determine N speciation and distribution in drainage water, soil, and headspace gases.
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
July 2008
We examined the effects of tetracycline (TET) addition on the function of mesocosms representing aerated and unaerated septic system leachfields. Replicate mesocosms (n = 3) were filled with soil and either vented to a leachfield (LEACH) or aerated intermittently to maintain an O(2) level of approximately 0.21 mol mol(-1) (AIR).
View Article and Find Full Text PDFJ Environ Sci Health A Tox Hazard Subst Environ Eng
September 2007
Antibiotics can be present in low concentrations in domestic wastewater, but little is known about their effect on bacteria in onsite wastewater treatment systems. Mesocosms, consisting of soil-filled lysimeters representing the leachfield of a septic system under aerated (AIR) and unaerated (LEACH) conditions, were used to study the effects of tetracycline addition (5 mg L(-1)) to septic tank effluent on tetracycline resistance in the fecal indicator bacteria Escherichia coli and fecal streptococci, and on their removal. The mesocosms were dosed with antibiotic for 10 days, and effects monitored for 52 days.
View Article and Find Full Text PDFLittle evidence or advice exists in the medical literature on 'medical kit' that could be usefully carried by physicians to prepare them for unexpected emergencies. The aim of this study was to establish what, in the opinion of Emergency Physicians, is an appropriate medical kit for doctors to carry to prepare them for 'Good Samaritan' acts. A telephone survey, using a proforma, of United Kingdom Emergency Physicians was conducted.
View Article and Find Full Text PDFIn September of 2004, we investigated 7 cases of post-myelography meningitis. Streptococcal species were recovered from blood or cerebrospinal fluid in all cases. Our findings suggest that droplet transmission of the oral flora of the clinician performing the procedure was the most likely source of these infections.
View Article and Find Full Text PDFAeration improves the capacity of leachfields to decontaminate and reduce the nutrient load of wastewater. To gain a better understanding of the effects of aeration, we examined the faunal and microbial communities of septic system leachfield soil (0-4 and 4-13 cm) using replicated (n = 3) mesocosms that were actively aerated (AIR) or unaerated (LEACH). Protozoa were 40 to 140 times more abundant in AIR than in LEACH soil.
View Article and Find Full Text PDFWe conducted a pilot-scale study at a research facility in southeastern Connecticut to assess the effects of leachfield aeration on removal of nutrients and pathogens from septic system effluent. Treatments consisted of lysimeters periodically aerated to maintain a headspace O(2) concentration of 0.209 mol mol(-1) (AIR) or vented to an adjacent leachfield trench (LEACH) and were replicated three times.
View Article and Find Full Text PDFBackground: Tissue damage at the time of organ transplantation has a negative impact on the subsequent success of the procedure, both in the immediate and longer term. Hypothermia is the principal element used to prolong organ viability ex vivo, but paradoxically also induces cellular edema through inhibition of energy-dependent adenosine triphosphatases (ATPases). This induces an electrolyte imbalance that leads to fluid influx and cell swelling.
View Article and Find Full Text PDFJ Manipulative Physiol Ther
August 2003
Objective: To quantify elements of spinal manipulation therapy performance and to test the strategy of combined rehearsal and quantitative feedback as a means of enhancing student skill development for cervical and thoracic manipulative procedures.
Design: Randomized, controlled study.
Setting: Chiropractic college.
J Manipulative Physiol Ther
October 2002
Objective: To quantify elements of spinal manipulation therapy performance and to test the strategy of combined rehearsal and quantitative feedback as a means of enhancing student skill development.
Design: Randomized, controlled study.
Setting: Chiropractic college.