Thermal hydrocracking of indan. Effects of the hydrogen pressure on the kinetics and Arrhenius parameters

The kinetics of the thermal hydrocracking of indan were investigatedin a high-pressure flow reactor at temperatures from 470 to 530°C, total pressures of up to 300 atm, and molar ratios from 3 to 40. The effect of the hydrogen pressure was reflected especially in a change of the experimental rate equations for the formation of toluene from rT=k [indan]0.5 [hydrogen] to rT=k [indan] 0.75[hydrogen]0.75 with hydrogen partial pressureincreasing from 73 to 230 atm. The rate equation of n-propylbenzene remained constant at rPr=k [indan] [hydrogen]1.5. Simultaneously the Arrheniusparameters of toluene changed significantly, while those of n-propylbenzene remained unchanged. \ud The observed effect of the hydrogen pressure is explained as a change inthe rates of the intermediate reactions; it provides an excellent agreementbetween the theoretical and experimental data. It was found that the steady-state concentration of the hydrogen atoms, which act as chain carriers in the thermal hydrocracking, was much smaller than the thermodynamic equilibrium concentration

Thermal high pressure hydrogenolysis II. The thermal high pressure hydrocracking of fluorene

The thermal hydrocracking of fluorene was investigated in the temperature range of 400 to 480 °C and hydrogen pressures of up to 375 atm. As main reaction products were found 2-methylbiphenyl, biphenyl, toluene and benzene. They account for about 90% of the converted fluorene. Only very low concentrations of diphenylmethane were detected at the highest temperature. This indicates that the opening of the phenyl - CH2 bond in fluorene is much faster than the splitting of the phenyl - phenyl bond. The splitting of the phenyl - phenyl bond in biphenyl, however, proceeded with a rate equal to the splitting of the phenyl - CH2 bond in fluorene and the phenyl - CH3 bond in 2-methylbiphenyl

INVESTIGATION OF THE HELMHOLTZ RESONATOR CONSIDERED AS A NON-ACOUSTIC OSCILLATING SYSTEM

In this paper the validity limits for a pulsating combustion unit have been determined, which has been designed for preheating diesel engines. An interesting phenomenon has been observed, namely the same pulsating frequency could be measured at two different resonator tube lengths. The paper presents an investigation of the basic causes of the frequency deviation of a pulsating combustion system built as a Helmholtz resonator and presents a frequency calculation for real systems. Furthermore, based on detailed investigation, it tries to explain the observed phenomenon

Mice haploinsufficient for Map2k7, a gene involved in neurodevelopment and risk for schizophrenia, show impaired attention, a vigilance decrement deficit and unstable cognitive processing in an attentional task: impact of minocycline

Rationale: Members of the c-Jun N-terminal kinase (JNK) family of mitogen-activated protein (MAP) kinases, and the upstream kinase MKK7, have all been strongly linked with synaptic plasticity and with the development of the neocortex. However, the impact of disruption of this pathway on cognitive function is unclear. Objective: In the current study, we test the hypothesis that reduced MKK7 expression is sufficient to cause cognitive impairment. Methods: Attentional function in mice haploinsufficient for Map2k7 (Map2k7+/− mice) was investigated using the five-choice serial reaction time task (5-CSRTT). Results: Once stable performance had been achieved, Map2k7+/− mice showed a distinctive attentional deficit, in the form of an increased number of missed responses, accompanied by a more pronounced decrement in performance over time and elevated intra-individual reaction time variability. When performance was reassessed after administration of minocycline—a tetracycline antibiotic currently showing promise for the improvement of attentional deficits in patients with schizophrenia—signs of improvement in attentional performance were detected. Conclusions: Overall, Map2k7 haploinsufficiency causes a distinctive pattern of cognitive impairment strongly suggestive of an inability to sustain attention, in accordance with those seen in psychiatric patients carrying out similar tasks. This may be important for understanding the mechanisms of cognitive dysfunction in clinical populations and highlights the possibility of treating some of these deficits with minocycline

Dilation, Transport, Visibility and Fault-Tolerant Algorithms

Connecting some points in the plane by a road network is equivalent to constructing a finite planar graph G whose vertex set contains a predefined set of vertices (i. e., the possible destinations in the road network). The dilation between two vertices p and q of graph G is defined as the Euclidean length of a shortest path in G from p to q, divided by the Euclidean distance from p to q. That is, given a point set P, the goal is to place some additional crossing vertices C such that there exists a planar graph G = (P ∪ C, E) whose dilation is small. Here, the dilation of G is defined as the maximum dilation between two vertices in G. We show that, except for some special point sets P, there is a lower bound Δ(P) > 1, depending on P, on the dilation of any finite graph containing P in its vertex set. The transportation problem is the problem of finding a transportation plan that minimizes the total transport cost. We are given a set of suppliers, and each supplier produces a fixed amount of some commodity, say, bread. Furthermore, there is a set of customers, and each customer has some demand of bread, such that the total demand equals the amount of bread the suppliers produce. The task is to assign each unit of bread produced to some customer, such that the total transportation cost becomes a minimum. A first idea is to assign each unit of bread to the client to which the transport cost of this unit is minimal. Clearly, this gives rise to a transportation plan which minimizes the total transportation cost. However, it is likely that not every customer will obtain the required amount of bread. Therefore, we need to use a different algorithm for distributing the supplier's bread. We show that if the bread produced by the suppliers is given by a continuous probability density function and the set of customers is discrete, then every optimal transport plan can be characterized by a unique additively weighted Voronoi diagram for the customers. When managing the construction process of a building by a digital model of the building, it is necessary to compute essential parts between walls of the building. Given two walls A and B, the essential part between A and B is the set of line segments s where one endpoint belongs to A, the other endpoint belongs to B, and s does not intersect A or B. We give an algorithm that computes, in linear time, the essential parts between A and B. Our algorithm is based on computing the visibility polygon of A and of B, and two shortest paths connecting points of A with points of B. We conclude the thesis by giving fault-tolerant algorithms for some fundamental geometric problems. We assume that a basic primitive operation used by an algorithm fails with some small probability p. Depending on the results of the primitive operations, it is possible that the algorithm will not work correctly. For example, one faulty comparison when executing a sorting algorithm can result in some numbers being placed far away from their true positions. An algorithm is called tolerant, if with high probability a good answer is given, if the error probability p is small. We provide tolerant algorithms that find the maximum of n numbers, search for a key in a sorted sequence of n keys, sort a set of n numbers, and solve Linear Programming in R2

DETERMINATION OF COMBUSTION STABILITY IN PULVERSIED COAL FUELLED STEAM BOILERS

Analysis of firing techniques in pulverized coal-fuelled boilers is a rather complex task. The scheduling of its realization depends on numerous local restricting factors (reliability of instrumentation, applicable loads, momentary quality of coal)

Point Set Isolation Using Unit Disks is NP-complete

We consider the situation where one is given a set S of points in the plane and a collection D of unit disks embedded in the plane. We show that finding a minimum cardinality subset of D such that any path between any two points in S is intersected by at least one disk is NP-complete. This settles an open problem raised by Matt Gibson et al[1]. Using a similar reduction, we show that finding a minimum cardinality subset D' of D such that R^2 - (D - D') consists of a single connected region is also NP-complete. Lastly, we show that the Multiterminal Cut Problem remains NP-complete when restricted to unit disk graphs