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12 results on '"Congiu, Martina"'

1. Synthesis and characterisation of luminescent lanthanide dyes for solar energy conversion

Author

Congiu, Martina, Robertson, Neil, and Jones, Anita

Subjects
621.47, Lanthanide (III) complexes, energy transfer, solar conversion devices, Chromium dioxalate, Luminescent Solar Concentrators
Abstract

Lanthanide (III) complexes are used extensively in solar conversion devices, such as Luminescent Solar Concentrators (LSCs) and Luminescent Down-Shifting (LDS) for their peculiar characteristics of narrow band emission, avoidance of re-absorption losses due to large Stokes shift and possibility of high photoluminescence quantum yield (PLQY). The study has looked into the synthesis of Ln (III) complexes of the general formula: [Ln(hfac)3DPEPO], where DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide, and hfac = hexafluoroacetylacetonate. The work presented in this thesis focuses on the synthesis, and subsequent photophysical characterisation of these Ln(III) complexes, plus characterisation and spectroscopic study of [Tb(pobz)3(hacim)2], (where Hpobz = phenoxybenzoic acid, and Hacim = acetylacetone imine), yielding results that open new design of functional Ln(III) systems. Spectroscopic study of Chromium dioxalate and analogous compounds has revealed that with the appropriate design, Cr(III)Ln(III) energy transfer can be achieved, while study of polyaromatic hydrocarbons (PAH) such as coronene, enable to explore a ligand with better absorption in the whole UV region. These results open attractive perspectives for light-conversion systems, such as LSC devices.

Published
2013

6. Intracortical motor conduction is associated with hand dexterity in progressive multiple sclerosis.

Author

Pisa, Marco, Chieffo, Raffaella, Congiu, Martina, Dalla Costa, Gloria, Esposito, Federica, Romeo, Marzia, Comola, Mauro, Comi, Giancarlo, and Leocani, Letizia

Subjects
TRANSCRANIAL magnetic stimulation, MULTIPLE sclerosis, EVOKED potentials (Electrophysiology), MOTOR ability, EFFERENT pathways
Abstract

Background: Hand dexterity dysfunction is a key feature of disability in people with progressive multiple sclerosis (PMS). It underlies corticospinal tract (CST) and cerebellar integrity, as well as disruption of cortical networks, which are hardly assessed by standard techniques. Transcranial magnetic stimulation is a promising tool for evaluating the integrity of intracortical motor pathways. Objective: To investigate neurophysiological correlates of motor hand impairment in PMS. Methods: Antero-posterior (AP) stimulation of the primary motor cortex activates the CST indirectly through polysynaptic pathways, while a direct CST activation occurs with latero-medial (LM) directed current. Thirty PMS and 15 healthy controls underwent dominant hand motor evoked potentials (MEP) using AP and LM-directed stimulation, and a clinical assessment of dexterity (nine-hole peg test) and strength (MRC scale, grip and pinch). Results: PMS with AP-LM latency difference 2.5 standard deviation above the mean of controls (33%) showed worse dexterity but no difference in upper limb strength. Accordingly, AP-LM latency shortening predicted dexterity (R2 = 0.538, p < 0.001), but not strength impairment. On the contrary, absolute MEP latencies only correlated with strength (grip: R2 = 0.381, p = 0.014; MRC: R2 = 0.184, p = 0.041). Conclusion: AP-LM latency shortening may be used to assess the integrity polysynaptic intracortical networks implicated in dexterity impairment. [ABSTRACT FROM AUTHOR]

Published
2021
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10. Preparation and photophysical studies of [Ln(hfac)3DPEPO], Ln = Eu, Tb, Yb, Nd, Gd; interpretation of total photoluminescence quantum yields.

Author

Congiu, Martina, Alamiry, Mohamed, Moudam, Omar, Ciorba, Serena, Richardson, Patricia R., Maron, Laurent, Jones, Anita C., Richards, Bryce S., and Robertson, Neil

Subjects
*PHOTOLUMINESCENCE, *ENERGY transfer, *CRYSTAL structure, *LUMINESCENCE quenching, *DENSITY functional theory
Abstract

Synthesis and photophysical characterisation of [Ln(hfac)3DPEPO] complexes (with Ln = Eu, Tb, Yb, Nd, Gd) has been carried out to investigate the factors responsible for the variation in total photoluminescence quantum yield within this family of emissive lanthanide complexes. Electronic absorption and emission spectroscopy, in conjunction with DFT calculations of the excited state of the Eu complex, elucidate the role of each ligand in the sensitisation of the lanthanide through the antenna effect. The X-ray crystal structure of [Gd(hfac)3DPEPO] has been determined and shows an 8-coordinate environment around the Gd and a ten-membered chelate ring involving the DPEPO ligand. Total photoluminescence quantum yields were measured to be 6%, 1% and 2% for Ln = Tb, Nd and Yb, respectively, in comparison with around 80% for Ln = Eu. The lower quantum yield for Nd and Yb, compared with Eu, can be attributed to more efficient quenching of the excited Ln state by high-energy oscillations within the ligands, whereas the lower quantum yield for Tb is assigned to a combination of poor energy transfer from the ligand excited state to the Tb and longer radiative lifetime. [ABSTRACT FROM AUTHOR]

Published
2013
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11. The Danger of Walking with Socks: Evidence from Kinematic Analysis in People with Progressive Multiple Sclerosis

Author

Letizia Leocani, Gloria Dalla Costa, Su Chun Huang, Martina Congiu, Giulia Leccabue, Lorenzo Gregoris, Marco Pisa, Giancarlo Comi, Huang, Su-Chun, Dalla Costa, Gloria, Pisa, Marco, Gregoris, Lorenzo, Leccabue, Giulia, Congiu, Martina, Comi, Giancarlo, and Leocani, Letizia

Subjects
Adult, Male, medicine.medical_specialty, inertial sensor, accelerator, Acceleration, Walking, Electromyography, lcsh:Chemical technology, multiple sclerosis, Biochemistry, Article, Clothing, Analytical Chemistry, T10MW, Muscle coactivation, 03 medical and health sciences, 0302 clinical medicine, Physical medicine and rehabilitation, Gait (human), medicine, Humans, lcsh:TP1-1185, Electrical and Electronic Engineering, Instrumentation, 0303 health sciences, Expanded Disability Status Scale, medicine.diagnostic_test, 030306 microbiology, business.industry, Biomechanics, Middle Aged, Coactivation, Atomic and Molecular Physics, and Optics, Biomechanical Phenomena, body regions, medicine.anatomical_structure, kinematics, Gait analysis, gait analysis, Quality of Life, Female, surface EMG, business, Cadence, human activities, 030217 neurology & neurosurgery
Abstract

Multiple sclerosis (MS) is characterized by gait impairments and severely impacts the quality of life. Technological advances in biomechanics offer objective assessments of gait disabilities in clinical settings. Here we employed wearable sensors to measure electromyography (EMG) and body acceleration during walking and to quantify the altered gait pattern between people with progressive MS (PwPMS) and healthy controls (HCs). Forty consecutive patients attending our department as in-patients were examined together with fifteen healthy controls. All subjects performed the timed 10 min walking test (T10MW) using a wearable accelerator and 8 electrodes attached to bilateral thighs and legs so that body acceleration and EMG activity were recorded. The T10MWs were recorded under three conditions: standard (wearing shoes), reduced grip (wearing socks) and increased cognitive load (backward-counting dual-task). PwPMS showed worse kinematics of gait and increased muscle coactivation than controls at both the thigh and leg levels. Both reduced grip and increased cognitive load caused a reduction in the cadence and velocity of the T10MW, which were correlated with one another. A higher coactivation index at the thigh level of the more affected side was positively correlated with the time of the T10MW (r = 0.5, p &lt, 0.01), Expanded Disability Status Scale (EDSS) (r = 0.4, p &lt, 0.05), and negatively correlated with the cadence (r = &minus, 0.6, p &lt, 0.001). Our results suggest that excessive coactivation at the thigh level is the major determinant of the gait performance as the disease progresses. Moreover, demanding walking conditions do not influence gait in controls but deteriorate walking performances in PwPMS, thus those conditions should be prevented during hospital examinations as well as in homecare environments.

Published
2020

12. Intracortical motor conduction is associated with hand dexterity in progressive multiple sclerosis.

Author

Pisa M, Chieffo R, Congiu M, Dalla Costa G, Esposito F, Romeo M, Comola M, Comi G, and Leocani L

Subjects
Evoked Potentials, Motor, Hand, Humans, Pyramidal Tracts, Transcranial Magnetic Stimulation, Motor Cortex, Multiple Sclerosis
Abstract

Background: Hand dexterity dysfunction is a key feature of disability in people with progressive multiple sclerosis (PMS). It underlies corticospinal tract (CST) and cerebellar integrity, as well as disruption of cortical networks, which are hardly assessed by standard techniques. Transcranial magnetic stimulation is a promising tool for evaluating the integrity of intracortical motor pathways., Objective: To investigate neurophysiological correlates of motor hand impairment in PMS., Methods: Antero-posterior (AP) stimulation of the primary motor cortex activates the CST indirectly through polysynaptic pathways, while a direct CST activation occurs with latero-medial (LM) directed current. Thirty PMS and 15 healthy controls underwent dominant hand motor evoked potentials (MEP) using AP and LM-directed stimulation, and a clinical assessment of dexterity (nine-hole peg test) and strength (MRC scale, grip and pinch)., Results: PMS with AP-LM latency difference 2.5 standard deviation above the mean of controls (33%) showed worse dexterity but no difference in upper limb strength. Accordingly, AP-LM latency shortening predicted dexterity (R 2  = 0.538, p  < 0.001), but not strength impairment. On the contrary, absolute MEP latencies only correlated with strength (grip: R 2  = 0.381, p  = 0.014; MRC: R 2  = 0.184, p  = 0.041)., Conclusion: AP-LM latency shortening may be used to assess the integrity polysynaptic intracortical networks implicated in dexterity impairment.

Published
2021
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