| 1. |
- Andreasson, Joakim, 1973, et al.
(författare)
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A simplicity-guided approach toward molecular set-reset memories
- 2010
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1369-9261 .- 1144-0546. ; 34:12, s. 2701-2703
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Tidskriftsartikel (refereegranskat)abstract
- Photochromic switches fulfill the general molecular design criteria for the surprisingly straightforward small-scale integration of seemingly complex set-reset latches. The implications of this re-interpretation are discussed with the example of a dithienylethene photochrome. The concept is shown to be valid for a multitude of well-introduced bistable switches with clearly differentiated output signals, e.g., optical signals for the presented example.
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| 2. |
- Andreasson, Joakim, 1973, et al.
(författare)
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All-Photonic Multifunctional Molecular Logic Device
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 133:30, s. 11641-11648
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Tidskriftsartikel (refereegranskat)abstract
- Photochromes are photoswitchable, bistable chromophores which, like transistors, can implement binary logic operations. When several photochromes are combined in one molecule, interactions between them such as energy and electron transfer allow design of simple Boolean logic gates and more complex logic devices with all-photonic inputs and outputs. Selective isomerization of individual photochromes can be achieved using light of different wavelengths, and logic outputs can employ absorption and emission properties at different wavelengths, thus allowing a single molecular species to perform several different functions, even simultaneously. Here, we report a molecule consisting of three linked photochromes that can be configured as AND, XOR, INH, half-adder, half-subtractor, multiplexer, demultiplexer, encoder, decoder, keypad lock, and logically reversible transfer gate logic devices, all with a common initial state. The system demonstrates the advantages of light-responsive molecules as multifunctional, reconfigurable nanoscale logic devices that represent an approach to true molecular information processing units.
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| 3. |
- Andreasson, Joakim, 1973, et al.
(författare)
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Smart molecules at work-mimicking advanced logic operations
- 2010
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Ingår i: Chemical Society Reviews. - : Royal Society of Chemistry (RSC). - 1460-4744 .- 0306-0012. ; 39:1, s. 174-188
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Tidskriftsartikel (refereegranskat)abstract
- Molecular logic is an interdisciplinary research field, which has captured worldwide interest. This tutorial review gives a brief introduction into molecular logic and Boolean algebra. This serves as the basis for a discussion of the state-of-the-art and future challenges in the field. Representative examples from the most recent literature including adders/subtractors, multiplexers/demultiplexers, encoders/decoders, and sequential logic devices (keypad locks) are highlighted. Other horizons, such as the utility of molecular logic in bio-related applications, are discussed as well.
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| 4. |
- Andreasson, Joakim, 1973, et al.
(författare)
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Storage and Processing of Information Using Molecules: The All-Photonic Approach with Simple and Multi-Photochromic Switches
- 2013
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Ingår i: Israel Journal of Chemistry. - : Wiley. - 0021-2148. ; 53:5, s. 236-246
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Forskningsöversikt (refereegranskat)abstract
- The use of photochromes for the implementation of molecular logic operations is a very promising approach toward molecular computing. This statement is based on a) the possibility of operating such molecular devices exclusively with photonic signals and b) spatiotemporally and remotely controlled switching, which is characteristic for photochromes. Herein, a brief overview of the application of simple photochromes and multi-photochromic conjugates for the small-scale functional integration of complicated logic circuits is given. This complements and extends efforts to design molecular photochromic memories for data storage described by many research groups worldwide.
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| 5. |
- Andreasson, U., et al.
(författare)
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An enzyme activity as a potential biomarker for Alzheimer's disease.
- 2010
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 6:4, s. 497-498
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Konferensbidrag (refereegranskat)abstract
- Background: Six different N-terminal amyloid precursor protein (APP) fragments, with molecular weight ∼12 kDa, have previously been identified in human cerebrospinal fluid (CSF). In a pilot study, both the sum of their concentrations, measured by western blot, and the relative abundance pattern, measured by mass spectrometry, were different in Alzheimer's disease (AD) patients compared to healthy controls. To test if these differences were also reflected in protease activities that possibly give rise to the ∼12 kDa fragments an enzymatic assay was developed and the activity in CSF was investigated for its potential as a biomarker for AD. Methods: The substrate in the protease activity assay was a custom made fluorochrome/quencher labeled peptide that covers the cleavage sites in APP (APP118-APP127) corresponding to the C-termini of the six ∼12 kDa APP fragments. The activity was measured in CSF from 55 AD patients and 17 controls. Results: There was a significant increase in the protease activity in CSF from AD patients compared to the controls (p = 0.001). This is in line with previous results which indicate that the sum of the ∼12 kDa fragments are elevated in AD. Results from inhibition studies strongly suggests that the enzyme responsible for the cleavage of the substrate is an aspartic protease since a sub nM IC50 value was recorded for Pepstatin A while no inhibition was observed for the cysteine protease specific inhibitor E64 at concentrations up to100 nM. Conclusions: There exists an enzymatic activity in CSF capable of cleaving a peptide substrate that spans a portion, close to the N-terminal, of APP. In a pilot study the activity is increased in AD patients compared to controls suggesting that it can be used as a biomarker.
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| 6. |
- Barty, A., et al.
(författare)
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Self-terminating diffraction gates femtosecond X-ray nanocrystallography measurements
- 2012
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Ingår i: Nature Photonics. - 1749-4885 .- 1749-4893. ; 6:1, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- X-ray free-electron lasers have enabled new approaches to the structural determination of protein crystals that are too small or radiation-sensitive for conventional analysis1. For sufficiently short pulses, diffraction is collected before significant changes occur to the sample, and it has been predicted that pulses as short as 10 fs may be required to acquire atomic-resolution structural information1, 2, 3, 4. Here, we describe a mechanism unique to ultrafast, ultra-intense X-ray experiments that allows structural information to be collected from crystalline samples using high radiation doses without the requirement for the pulse to terminate before the onset of sample damage. Instead, the diffracted X-rays are gated by a rapid loss of crystalline periodicity, producing apparent pulse lengths significantly shorter than the duration of the incident pulse. The shortest apparent pulse lengths occur at the highest resolution, and our measurements indicate that current X-ray free-electron laser technology5 should enable structural determination from submicrometre protein crystals with atomic resolution.
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| 7. |
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| 8. |
- Beijer, U, et al.
(författare)
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Mortality and causes of death among homeless women and men in Stockholm
- 2011
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Ingår i: Scandinavian journal of public health. - : SAGE Publications. - 1651-1905 .- 1403-4948. ; 39:2, s. 121-127
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To study the mortality and causes of death among homeless men and women in relation to the risk indicators, previous treatment for alcohol and drug abuse, previous treatment for mental disorders and non-Swedish citizenship. Methods: The mortality was studied in a cohort comprising 1,757 men and 526 women compared with the general population and persons with inpatient treatment for alcohol- and drug-related disorders. The follow-up period was from 1995 to 1997 until the end of 2005. The causes of death were analyzed. Results: 421 deaths occurred during the follow-up period. The relative risk of death was 3.1, with no difference in mortality between homeless men and homeless women. Previous treatment for alcohol and drug abuse disorders was related to excess mortality and previous treatment for mental disease to lower mortality. Homeless people with inpatient treatment for alcohol or drug use disorders had no higher mortality than the general population in Stockholm with a similar history. There was a dominance of alcohol- and drug-related causes of death. Discussion: Compared with previous studies of homeless people in Stockholm the excess mortality among men found in this study is of the same magnitude. Mortality among women is lower. The mortality rate in homeless people with previous treatment for an alcohol and illicit drug use disorder did not differ from those treated for these disorders in the general population. Conclusions: The most important finding is that excess mortality among homeless men and women in Stockholm is entirely related to alcohol and drug abuse.
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| 9. |
- Bälter, Magnus, 1986, et al.
(författare)
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An All-Photonic Molecule-Based Parity Generator/Checker for Error Detection in Data Transmission
- 2013
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 135:28, s. 10230-10233
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Tidskriftsartikel (refereegranskat)abstract
- The function of a parity generator/checker, which is an essential operation for detecting errors in data transmission, has been realized with multiphotochromic switches by taking advantage of a neuron-like fluorescence response and reversible light-induced transformations between the implicated isomers.
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| 10. |
- Gust, D., et al.
(författare)
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Data and signal processing using photochromic molecules
- 2012
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 48:14, s. 1947-1957
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Tidskriftsartikel (refereegranskat)abstract
- Photochromes are chromophores that are reversibly isomerized between two metastable forms using light, or light and heat. When photochromes are covalently linked to other chromophores, they can act as molecular photonic analogues of electronic transistors. As bistable switches, they can be incorporated into the design of molecules capable of binary arithmetic and both combinatorial and sequential digital logic operations. Small ensembles of such molecules can perform analogue signal modulation similar to that carried out by transistor amplifiers. Examples of molecules that perform multiple logic functions, act as control elements for fluorescent reporters, and mimic natural photoregulatory functions are presented.
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