In this work, partial thermodynamic properties of polyhydroxylated dibenzo-p-dioxins （PHODDs） are calculated by density functional theory （DFT） with the Gaussian 03 program at the B3LYP/6-311G^＊＊ level. By compa...In this work, partial thermodynamic properties of polyhydroxylated dibenzo-p-dioxins （PHODDs） are calculated by density functional theory （DFT） with the Gaussian 03 program at the B3LYP/6-311G^＊＊ level. By comparing the total energy Eθ values, it is found that two types of hydrogen bonds exist in PHODDs, one between a hydroxyl and the parent compound （dibenzop-dioxin） with bond energy of approximate 15.7 kJ/mol and the other between two ortho hydroxyl groups with higher bond energy of about 18.3 kJ/mol. Hydrogen bonds have an effect on the conformation stability. On the basis of evaluating the strength of these two types of hydrogen bonds, 75 most stable congeners are ascertained. The relations of calculated thermodynamic parameters （total energy E^θ, zero-point vibrational energy ZPE, correction value of thermal energy Ethθ, heat capacity at constant volume CV^θ） with the number and position of hydroxyl substitution （NPHOS） are also discussed. The results show that the NPHOS models can be used to predict the thermodynamic properties for PHODD congeners. In addition, the values of molar heat capacities at constant pressure （Cp,m） from 200 to 1000 K for PHODD congeners are calculated, and the temperature dependence relation of Cp,m is obtained with the least-squares method.展开更多
For years, rumors have circulated that the code for the original DOS operating system created by Microsoft for the IBM personal computer is actually copied from the CP/M operating system developed by Digital Research ...For years, rumors have circulated that the code for the original DOS operating system created by Microsoft for the IBM personal computer is actually copied from the CP/M operating system developed by Digital Research Incorporated. In this paper, scientifically tested and accepted forensic analysis mathematical techniques, step-by-step processes, and advanced software code comparison tools are used to compare early versions of the two code bases. The conclusion is reached that no copying of code takes place1.展开更多
In a previous paper [1], I compared DOS from Microsoft and CP/M from Digital Research Inc. (DRI) to determine whether the original DOS source code had been copied from CP/M source code as had been rumored for many yea...In a previous paper [1], I compared DOS from Microsoft and CP/M from Digital Research Inc. (DRI) to determine whether the original DOS source code had been copied from CP/M source code as had been rumored for many years [2] [3]. At the time, the source code for CP/M was publicly available but the source code for DOS was not. My comparison was limited to the comparison of the DOS 1.11 binary code and the source code for CP/M 2.0 from 1981. Since that time, the Computer History Museum in Mountain View, California received the source code for DOS 2.0 from Microsoft and was given permission to make it public. The museum also received the source code for DOS 1.1 from Tim Paterson, the developer who was originally contracted by Microsoft to write DOS. In this paper, I perform a further analysis using the newly accessible source code and determine that no code was copied. I further conclude that the commands were not copied but that a substantial number of the system calls were copied.展开更多
基金supported by the National Natural Science Foundation of China (41071319, 20977046, 20737001)
文摘In this work, partial thermodynamic properties of polyhydroxylated dibenzo-p-dioxins （PHODDs） are calculated by density functional theory （DFT） with the Gaussian 03 program at the B3LYP/6-311G^＊＊ level. By comparing the total energy Eθ values, it is found that two types of hydrogen bonds exist in PHODDs, one between a hydroxyl and the parent compound （dibenzop-dioxin） with bond energy of approximate 15.7 kJ/mol and the other between two ortho hydroxyl groups with higher bond energy of about 18.3 kJ/mol. Hydrogen bonds have an effect on the conformation stability. On the basis of evaluating the strength of these two types of hydrogen bonds, 75 most stable congeners are ascertained. The relations of calculated thermodynamic parameters （total energy E^θ, zero-point vibrational energy ZPE, correction value of thermal energy Ethθ, heat capacity at constant volume CV^θ） with the number and position of hydroxyl substitution （NPHOS） are also discussed. The results show that the NPHOS models can be used to predict the thermodynamic properties for PHODD congeners. In addition, the values of molar heat capacities at constant pressure （Cp,m） from 200 to 1000 K for PHODD congeners are calculated, and the temperature dependence relation of Cp,m is obtained with the least-squares method.
文摘For years, rumors have circulated that the code for the original DOS operating system created by Microsoft for the IBM personal computer is actually copied from the CP/M operating system developed by Digital Research Incorporated. In this paper, scientifically tested and accepted forensic analysis mathematical techniques, step-by-step processes, and advanced software code comparison tools are used to compare early versions of the two code bases. The conclusion is reached that no copying of code takes place1.
文摘In a previous paper [1], I compared DOS from Microsoft and CP/M from Digital Research Inc. (DRI) to determine whether the original DOS source code had been copied from CP/M source code as had been rumored for many years [2] [3]. At the time, the source code for CP/M was publicly available but the source code for DOS was not. My comparison was limited to the comparison of the DOS 1.11 binary code and the source code for CP/M 2.0 from 1981. Since that time, the Computer History Museum in Mountain View, California received the source code for DOS 2.0 from Microsoft and was given permission to make it public. The museum also received the source code for DOS 1.1 from Tim Paterson, the developer who was originally contracted by Microsoft to write DOS. In this paper, I perform a further analysis using the newly accessible source code and determine that no code was copied. I further conclude that the commands were not copied but that a substantial number of the system calls were copied.
