Hiroshi Nakamura

Bio: Hiroshi Nakamura is an academic researcher from Kyushu University. The author has contributed to research in topics: Crown ether & Electron transfer. The author has an hindex of 34, co-authored 230 publications receiving 3876 citations. Previous affiliations of Hiroshi Nakamura include Hokkaido University & Mitsubishi.

Remote authentication system

Abstract: To obtain a remote authentication system that securely authenticates with protecting biometrics information, which is user's personal information, and is firm on security when performing authentication of a person with the biometrics information, and a remote authentication method. The present invention encrypts biometrics information that is user's personal information, and transfers the biometrics information over a network in such a state that only an authentication server, which the user assigns, can decode the biometrics information. Therefore, it is possible to securely protect user's privacy that is the biometrics information in a style of reflecting user's intention, and to prevent reuse of invalid authentication information since it is possible to confirm the date and time, when the authentication information was generated, by the authentication server. Furthermore, it is possible to keep the security of a system firm since an authenticated side can confirm whether the user is authenticated.

Ten year recurrence after first ever stroke in a Japanese community: the Hisayama study

Abstract: Background: Very few population based cohort studies have focused on the long term recurrence of stroke. Objective: To examine 10 year cumulative recurrence rates for stroke in a Japanese cohort according to pathological type and clinical subtype of brain infarction. Methods: During a 32 year follow up of 1621 subjects ⩾40 years of age, 410 developed first ever stroke. These were followed up prospectively for 10 years after stroke onset. Results: During follow up, 108 (26%) experienced recurrent stroke. The cumulative recurrence rates were 35.3% at five years and 51.3% at 10 years. The 10 year recurrence rates of subarachnoid haemorrhage (SAH), brain haemorrhage, and brain infarction were 70.0%, 55.6%, and 49.7%, respectively; the difference between SAH and brain infarction was significant (p = 0.004). Most recurrent episodes after SAH or brain haemorrhage happened within a year after the index stroke, whereas recurrence of brain infarction increased consistently throughout the observation period. Cardioembolic stroke had a higher recurrence rate (75.2%) than lacunar infarction (46.8%) (p = 0.049). The 10 year risk of stroke recurrence increased with age after lacunar or atherothrombotic brain infarction, but not after the other types or subtypes. After atherothrombotic brain infarction, cardioembolic stroke, or SAH, the type and subtype of most recurrent strokes were the same as for the index stroke, but recurrence after lacunar infarction or brain haemorrhage showed divergent patterns. Conclusions: Japanese people have higher recurrence rates of stroke than other populations. Recurrence rate after a first brain infarct increases consistently through the next 10 years.

New Fluorimetric Alkali and Alkaline Earth Metal Cation Sensors Based on Noncyclic Crown Ethers by Means of Intramolecular Excimer Formation of Pyrene

Abstract: New fluorescent reagents, 2,2‘-[oxybis(3-oxapentamethyleneoxy)]-bis[N-(1-pyrenylmethyl)benzamide)] (4) and its analogues (2, 3, and 5) which have two pyrenes at the both terminals of polyoxyethylene compounds, were synthesized, and their complexation behavior with alkaline earth cations was investigated by fluorescence spectrometry, fluorescence lifetimes, and 1H NMR spectrometry. These reagents (3−5) showed strong intramolecular excimer emissions around at 480 nm in the fluorescence spectra. On the complexation with alkaline earth metal cations, the increase of monomer emission around at 400 nm accompanied by the disappearance of intramolecular excimer emission of free reagents was observed. These reagents formed a 1:1 complex, and the order of complex formation constants was Ca2+ ≅ Sr2+ > Ba2+ > Mg2+ > Li+ for all reagents. 1H NMR spectra of these complexes with alkaline earth cations suggested the helical structures of the complexes. Fluorescence spectral changes at the formation of complexes depended ...

Synthetic molecular motors and mechanical machines.

Abstract: The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.