V.M. Maximenko

Evaluation of Cellulase Preparations for Hydrolysis of Hardwood Substrates

Seven cellulase preparations from Penicillium and Trichoderma spp. were evaluated for their ability to hydrolyze the cellulose fraction of hardwoods (yellow poplar and red maple) pretreated by organosolv extraction, as well as model cellulosic substrates such as filter paper. There was no significant correlation among hydrolytic performance on pretreated hardwood, based on glucose release, and filter paper activity. However, performance on pretreated hardwood showed significant correlations to the levels of endogenous β-glucosidase and xylanase activities in the cellulase preparation. Accordingly, differences in performance were reduced or eliminated following supplementation with a crude β-glucosidase preparation containing both activities. These results complement a previous investigation using softwoods pretreated by either organosolv extraction or steam explosion. Cellulase preparations that performed best on hardwood also showed superior performance on the softwood substrates.

Observation Of Very High Energy Cosmic-ray Families In Emulsion Chambers At High Mountain Altitudes (i)

Characteristics of cosmic-ray hadronic interactions in the 1015 − 1017 eV range are studied by observing a total of 429 cosmic-ray families of visible energy greater than 100 TeV found in emulsion chamber experiments at high mountain altitudes, Chacaltaya (5200 m above sea level) and the Pamirs (4300 m above sea level). Extensive comparisons were made with simulated families based on models so far proposed, concentrating on the relation between the observed family flux and the behaviour of high-energy showers in the families, hadronic and electromagnetic components. It is concluded that there must be global change in characteristics of hadronic interactions at around 1016 eV deviating from thise known in the accelerator energy range, specially in the forwardmost angular region of the collision. A detailed study of a new shower phenomenon of small-pT particle emissions, pT being of the order of 10 MeV/c, is carried out and its relation to the origin of huge “halo” phenomena associated with extremely high energy families is discussed as one of the possibilities. General characteristics of such super-families are surveyed.

Observation of a high-energy cosmic-ray family caused by a Centauro-type nuclear interaction in the joint emulsion chamber experiment at the Pamirs

Abstract An exotic cosmic-ray family event is observed in the large emulsion chamber exposed by the joint at the Pamirs (4360 m above sea level). The family is composed of 120 γ -ray-induced showers and 37 hadron-induced showers with individual visible energy exceeding 1 TeV. The decisive feature of the event is the hadron dominance: ΣE γ , ΣE ( γ ) h , 〈 E γ , 〈 E ( γ ) h 〉, 〈 E γ · R γ 〉 and 〈 E ( γ ) · R h 〉 being 298 TeV, 476 TeV, 2.5 TeV, 12.9 TeV, 28.6 GeV m and 173 GeV m, respectively. Most probably the event is due to a Centauro interaction, which occured in the atmosphere at ∼700 m above the chamber. The event will constitute the second beautiful candidate for a Centauro observed at the Pamirs.

An Evaluation of British Columbian Beetle-Killed Hybrid Spruce for Bioethanol Production

The development of bioconversion technologies for production of fuels, chemicals, and power from renewable resources is currently a high priority for developed nations such as the United States, Canada, and the European Union as a way to improve national energy security and reduce greenhouse gas emissions. The widespread implementation of such technologies will require a sustainable supply of biomass from forestry and agriculture. Forests are a major source of feedstocks for biofuels production in Canada. Woody biomass includes residues from logging and forest thinning, and from wood processing and pulp production.More recently, damaged wood caused by beetle infestations has become available on a large scale in Western Canada. This study evaluates beetle-killed British Columbian hybrid spruce (HS) (Picea glauca × P. engelmannii) as a feedstock for the production of bioethanol. In the past 30 yr, attack by the beetle Dendroctonus rufipennis and associated fungi has resulted in estimated losses of more than three billion board feet in British Columbia alone. Here we describe the chemical and some physical characteristics of both healthy (HHS) and beetle-killed (BKHS) British Columbian HS and evaluate the technical feasibility of using these feedstocks as a source of biomass for bioethanol production. Untreated HHS and BKHS did not differ significantly in chemical composition except for the moisture content, which was significantly lower in BKHS (approx 10%) compared with HHS (approx 18%). However, the yields of carbohydrates in hydrolyzable and fermentable forms were higher at mild pretreatment conditions (H-Factor <1000) for BKHS compared with HHS. At medium (H-Factor 1000–2000) and severe (H-Factor >2000) pretreatment conditions HHS and BKHS behaved similarly. Organosolv pretreated HHS and BKHS demonstrated good ethanol theoretical yields, approx 70 and 80%, respectively.

Intense bundles of particles in cores of nuclear-electromagnetic cascades in the atmosphere with energies around 100 PeV (gamma-families with halo)

An appreciable fraction of gamma-families are accompanied by a halo, a narrow bundle of high-energy particles (energy density > 20 TeV/mm2) recorded in X-ray emulsion chambers as a diffuse dark spot in the central region of a gamma-family. Gamma-families in the experiment “Pamir” are compared with simulations by three different codes of quark-gluon string model (MQ, MCO and QGSJet) based on extrapolating accelerator data up to energy Eo = 3 ∗ 1018 eV and under various assumptions on mass composition of primary cosmic rays (PCR). The spectrum of halo area, S, is analyzed, especially at S > 100 mm2. Simulations by different codes predict that at a PCR energy Eo ∼ 1018 eV the probability of initiating a halo with S ∼ 1000 mm2 is 60% for primary protons and 40% for Fe nuclei. The fraction of protons in PCR composition at E0 = 1016 ÷ 1017 eV is estimated.

Fraction of protons in primary cosmic rays according to data from the PAMIR experiment in consideration of the response of X-ray emulsion chambers

Adjusted data on the fraction of protons in the mass composition of primary cosmic rays (PCRs) in the energy range of 1015–1017 eV are presented. Adjustments are made according to detailed calculations of the response of the X-ray emulsion chamber in the PAMIR experiment. It is demonstrated that the fraction of protons in a PCR is 16–18% for E0 ≈ 1015–1016 eV and does not change within the error for E0 ≈ 1016–1017 eV.

Mass composition of primary cosmic radiation according to data on spectrum of “halo” areas

Spectrum of “halo” areas in gamma-hadron families with ∑ Eγ ≥ 500 TeV is analyzed. The comparison of experimental data and simulations by quark-gluon string model suggests an increasing contribution of nuclei heavier than protons and α-particles to the primary cosmic radiation (PCR) at energy E0 > 1016 eV. Such a model is consistent both with the accelerator data and those from X-ray emulsion chamber experiments under assumption that PCR mass composition is normal for E0

Revised data on γ-families observed in X-ray emulsion chambers of the Experiment PAMIR

Recently essential efforts were made to improve measurement routine with X-ray films exposed in the X-ray emulsion chambers at the Pamirs. Analysis of X-ray emulsion response upon recorded events show that gamma-family energy and intensity in early publications were over estimated. The main physical results of the new analysis are presented.Recently essential efforts were made to improve measurement routine with X-ray films exposed in the X-ray emulsion chambers at the Pamirs. Analysis of X-ray emulsion response upon recorded events show that gamma-family energy and intensity in early publications were over estimated. The main physical results of the new analysis are presented.

High energy gamma-families with halo and mass composition of primary cosmic rays in energy region above 10 PeV

Abstract The experimental spectrum of halo areas for gamma-families with Σ E γ ≥ 500 TeV is obtained and compared with simulations in quark-gluon string model. The comparison suggests a ∼ 2 times decrease of the proton fraction in primary cosmic ray (PCR) composition in the energy region 10 16 ÷ 10 17 eV. However at an energy above 10 17 eV, the experimental flux of halo events with area exceeding 300 ÷ 400 mm 2 is 5 ÷ 10 times larger than the simulated one. Such a difference may be explained by the assumption that in this region the fraction of protons increases as much as 3 times, while the slope of the spectrum decreases (γ = 2.6 ÷ 2.7).

The characteristics of gamma-hadron families induced by primary cosmic rays with an energy more than 10 PeV

Parameters R ¯ > , ER ¯ > of gamma-hadron families with a visible energy Σ E γ ≥ 100 TeV are analysed with the aim to prove their sensitivity to the mass composition of primary cosmic rays (PCR). The experimental values of these parameters are in agreement with the assumption that PCR become enriched with CNO nuclei at an energy ≥ 10 16 PeV.