Observation of gapped state in rare-earth monopnictide HoSb.

The rare-earth monopnictide family is attracting an intense current interest driven by its unusual extreme magnetoresistance (XMR) property and the potential presence of topologically non-trivial surface states. The experimental observation of non-trivial surface states in this family of materials are not ubiquitous. Here, using high-resolution angle-resolved photoemission spectroscopy, magnetotransport, and parallel first-principles modeling, we examine the nature of electronic states in HoSb. Although we find the presence of bulk band gaps at the [Formula: see text] and X-symmetry points of the Brillouin zone, we do not find these gaps to exhibit band inversion so that HoSb does not host a Dirac semimetal state. Our magnetotransport measurements indicate that HoSb can be characterized as a correlated nearly-complete electron-hole-compensated semimetal. Our analysis reveals that the nearly perfect electron-hole compensation could drive the appearance of non-saturating XMR effect in HoSb.

Temozolomide-induced desquamative skin rash in a patient with metastatic melanoma.

Temozolomide is an oral alkylating agent used in the treatment of metastatic melanoma. Commonly reported adverse effects of the drug include nausea and vomiting, constipation, headache, and fatigue, as well as myelosuppression, which may be dose limiting. Few reports have described dermatologic adverse effects such as rash and pruritus, and, to our knowledge, none have discussed the seriousness or extensiveness of the rash. We describe a 37-year-old woman who was receiving temozolomide for treatment of metastatic melanoma. After 6 weeks of therapy, the patient developed an unexplained fever. The drug was discontinued, and the fever resolved within 2 days. Temozolomide was restarted 2 months later; the patient again developed a fever. This time the fever was accompanied by a diffuse erythematous skin rash that progressed to an extensive, full-body, desquamative skin rash. The rash was treated with moisturizing cream along with intravenous and topical corticosteroids and antibiotics. Due to the severity of the rash, temozolomide was permanently discontinued. Even after its discontinuation, the patient experienced the rash on a long-term basis, with periodic exacerbations. However, none were as severe as the first rash. The patient's metastatic disease remained stable for the next 2 years. According to the Naranjo adverse drug reaction probability scale, the likelihood that temozolomide was responsible for the adverse drug reaction of fever was probable (score of 6). Clinicians should be aware that an erythematous and exfoliative rash may be induced by temozolomide, and be familiar with the pharmacologic and supportive measures necessary for its treatment.

Triacylglycerol structure and composition of hydrogenated soybean oil margarine and shortening basestocks.

The composition and structures of triacylglycerols (TAG) in a commercially prepared hydrogenated soybean oil margarine basestock [iodine value (IV) 65, 39.7% trans fatty acids] were determined by high-performance liquid chromatography (HPLC) in tandem with atmospheric pressure chemical ionization (APCI) mass spectrometry (MS). The basestock was separated by preparative HPLC into four fractions. Fractions 1 and 4, constituting approximately 8% of the total, were shown to consist of LOO, PLO, and LLS and OSS and PSS, respectively (where L = linoleic, O = oleic, S = stearic, and P = palmitic). APCI will not distinguish between O, oleic cis C18:1, and E, elaidic trans C18:1. Thus, O and E may be used interchangeably in discussion of TAG isomer structures. Fraction 2 consisted of OOO and POO. Fraction 3 consisted of OOO, POO, OOS, and POS. About 80% of the total triglycerides consisted of OOO, POO, and OOS. The trans fatty acid content of the fractions was determined, and the results showed that 92% of the total trans content was found in fractions 2 and 3. A shortening basestock (IV 81.7, 31.8% trans fatty acids) was partially characterized.

Enhancing quality and oxidative stability of aged fried food with gamma-tocopherol.

To determine the effects of gamma-tocopherol on the stability of fried food, potato chips were fried in triolein with 0, 100, or 400 ppm gamma-tocopherol. Potato chips, sampled at 1, 3, and 6 h of frying time, were aged for 0, 2, and 4 days at 60 degrees C and then evaluated for odor attributes by sensory analysis and for volatile compounds by purge-and-trap gas chromatography-mass spectrometry. Oil sampled after 1, 3, and 6 h of frying time from the fryer was evaluated for total polar compounds and retention of gamma-tocopherol. Oil extracted from the potato chips was also analyzed for residual gamma-tocopherol. gamma-Tocopherol disappeared rapidly, with only slight amounts of the original 100 ppm level detectable after the triolein was used for frying. gamma-Tocopherol significantly inhibited polar compound production in the triolein. Results showed that gamma-tocopherol inhibited the oxidation of the fried food even when only very low levels of retained gamma-tocopherol were present in the frying oil or potato chips. Nonanal formation was inhibited by gamma-tocopherol in aged potato chips. Odor analysis of the aged potato chips showed that samples with 0 ppm gamma-tocopherol had a rancid odor after being aged for 4 days. Potato chips with 400 ppm gamma-tocopherol had no rancid odors; however, as the level of gamma-tocopherol decreased in the triolein and in the potato chips, a weak plastic odor characteristic of oxidized triolein was detected.

Modeling of hydrogenation kinetics from triglyceride compositional data.

A mathematical model was developed to describe the reduction of soybean oil triglycerides during hydrogenation. The model was derived from reaction and transport mechanisms and formulated into a system of first-order irreversible rate expressions that included terms for temperature, hydrogen pressure, and catalyst concentration. The model parameters were estimated from experimental data, and the model was used to simulate the results of hydrogenation performed over the pressure range of 0.069-6.9 MPa. The model could be extended to include geometrical isomers formed during hydrogenation.

Dual parallel electrospray ionization and atmospheric pressure chemical ionization mass spectrometry (MS), MS/MS and MS/MS/MS for the analysis of triacylglycerols and triacylglycerol oxidation products.

Two mass spectrometers, in parallel, were employed simultaneously for analysis of triacylglycerols in canola oil, for analysis of triolein oxidation products, and for analysis of triacylglycerol positional isomers separated using reversed-phase high-performance liquid chromatography. A triple quadrupole mass spectrometer was interfaced via an atmospheric pressure chemical ionization (APCI) interface to two reversed-phase liquid chromatographic columns in series. An ion trap mass spectrometer was coupled to the same two columns using an electrospray ionization (ESI) interface, with ammonium formate added as electrolyte. Electrospray ionization mass spectrometry (ESI-MS) under these conditions produced abundant ammonium adduct ions from triacylglycerols, which were then fragmented to produce MS/MS spectra and then fragmented further to produce MS/MS/MS spectra. ESI-MS/MS of the ammoniated adduct ions gave product ion mass spectra which were similar to mass spectra obtained by APCI-MS. ESI-MS/MS produced diacylglycerol fragment ions, and additional fragmentation (MS/MS/MS) produced [RCO](+) (acylium) ions, [RCOO+58](+) ions, and other related ions which allowed assignment of individual acyl chain identities. APCI-MS of triacylglycerol oxidation products produced spectra like those reported previously using APCI-MS. APCI-MS/MS produced ions related to individual fatty acid chains. ESI-MS of triacylglycerol oxidation products produced abundant ammonium adduct ions, even for those molecules which previously produced little or no intact molecular ions under APCI-MS conditions. Fragmentation (MS/MS) of the [M+NH(4)](+) ions produced results similar to those obtained by APCI-MS. Further fragmentation (MS/MS/MS) of the diacylglycerol fragments of oxidation products provided information on the oxidized individual fatty acyl chains. ESI-MS and APCI-MS were found to be complementary techniques, which together contributed to a better understanding of the identities of the products formed by oxidation of triacylglycerols.

The Denver Brown Cloud Studies from the Perspective of Model Assessment Needs and the Role of Meteorology.

The 1987-1988 Denver Brown Cloud Study addressed Denver's severe winter brown cloud episodes in a three-month field study followed by the application of a receptor-oriented chemical mass balance modeling method to apportion light extinction to primary emissions. However, this modeling method did not apportion light extinction from secondary particulates to individual sources. Recently, an independent meteorological and chemical modeling study, driven by the need to apportion secondary particles, reported on the initial numerical simulation of visibility for two days during the winter of 1987-1988. The MM4 meteorological model used in this recent study was operated in a four-dimensional, data-assimilation mode using standard, low-resolution synoptic observations and analyses. The chemical and aerosol numerical modeling system, which uses the MM4 meteorological model numerical output, was derived from the family of models developed for the National Acid Precipitation Assessment Program. This paper summarizes the meteorological features underlying the Denver brown cloud and assesses the consistency of the reported numerical simulations with the detailed meteorological observations available for the same periods. We found that the meteorological model, in its current form and range of application, does not address some of the critical mesoscale structures responsible for the initiation and maintenance of the brown cloud episodes studied nor, under some circumstances, does it properly predict boundary layer properties compared with observations. In addition, cloud systems and surface moisture fluxes are not addressed by the model, although many chemical processes depend on the presence of additional moisture. Comparison between model results and observations suggest that moist processes, particularly during the initiation phase of episodes, should be a critical issue for future experimental and modeling exercises. In addition, the limited model results available, when evaluated against the detailed boundary layer observations of the Brown Cloud Study, suggest that model uncertainties in the treatment of local terrain influence, boundary layer depth, and humidity may have obscured model overestimates of optical extinction. Finally, we suggest that although models will remain limited in many aspects, their use in combination with detailed observations of meteorology and chemistry will prove a valuable tool in the assessment of urban visibility issues.