Alterations In Electrical Conductivity Research Articles

Comprehensive Review on the Impact of Chemical Composition, Plasma Treatment, and Vacuum Ultraviolet (VUV) Irradiation on the Electrical Properties of Organosilicate Films.

Organosilicate glass (OSG) films are a critical component in modern electronic devices, with their electrical properties playing a crucial role in device performance. This comprehensive review systematically examines the influence of chemical composition, vacuum ultraviolet (VUV) irradiation, and plasma treatment on the electrical properties of these films. Through an extensive survey of literature and experimental findings, we elucidate the intricate interplay between these factors and the resulting alterations in electrical conductivity, dielectric constant, and breakdown strength of OSG films. Key focus areas include the impact of diverse organic moieties incorporated into the silica matrix, the effects of VUV irradiation on film properties, and the modifications induced by various plasma treatment techniques. Furthermore, the underlying mechanisms governing these phenomena are discussed, shedding light on the complex molecular interactions and structural rearrangements occurring within OSG films under different environmental conditions. It is shown that phonon-assisted electron tunneling between adjacent neutral traps provides a more accurate description of charge transport in OSG low-k materials compared to the previously reported Fowler-Nordheim mechanism. Additionally, the quality of low-k materials significantly influences the behavior of leakage currents. Materials retaining residual porogens or adsorbed water on pore walls show electrical conductivity directly correlated with pore surface area and porosity. Conversely, porogen-free materials, developed by Urbanowicz, exhibit leakage currents that are independent of porosity. This underscores the critical importance of considering internal defects such as oxygen-deficient centers (ODC) or similar entities in understanding the electrical properties of these materials.

Evaluation of ibuprofen drug assay using silicon doped graphdiyne: insights from density functional theory

An exploration into the electronic characteristics of graphene nanosheets (GDY) and its silicon-doped counterpart, SiGDY, was undertaken through the application of first-principle calculations. Analysis was conducted concerning the interaction between the ibuprofen (IBP) pharmaceutical and the surfaces of GDY and SiGDY sheet materials. This research undertook an evaluation of various factors like the energy of adsorption, transfer of charge, and alterations in electrical conductivity. The findings of this analysis revealed that the original GDY displayed minimal affinity towards IBP. Upon the attachment of IBP, there was a mere 8.92 percent marginal change observed in the energy range of the GDY surface. The interaction between SiGDY and IBP showcased an aqueous energy measurement of −49.11 kcal/mol, accompanied by a gaseous energy measurement of −20.09 kcal/mol. Utilising the pharmaceutical's solvation energy value, its solubility in the aqueous phase was determined. The profoundly positively charged SiGDY sheet and IBP underwent substantial charge transfer, engendering the essential binding energy for IBP adherence. The electrical conductivity of SiGDY underwent a noteworthy increase of roughly 26.41 percent upon the attachment of IBP.

Use of Ethanol Injections to Create a Complete Atrioventricular Block in a Rat Model

Complete atrioventricular block (AVB) is an abnormal heart rhythm resulting from a defect in the cardiac conduction system. Patients with complete AVB are at risk of symptoms ranging from syncope or hypotension to cardiovascular collapse or sudden cardiac death. A reliable animal model of complete AVB is essential for understanding the mechanisms underlying the fatal hemodynamic effects and alterations in electrical conductivity associated with this arrhythmia. We evaluated the use of ethanol injections in a systematic surgical approach to create a complete AVB model in rats. We used eight Sprague Dawley rats (8 weeks old, 220 ± 30 g): four received a 70% ethanol injection in the AV node, and four received a similar injection of 0.9% sodium chloride. Our surgical approach involved performing a partial sternotomy, using the epicardial fat as a landmark for ethanol injections. Animals were followed for 7 and 14 days. Complete AVB was successfully induced in all four rats that received ethanol injections. Rats in the control group experienced a transient AVB with a return to sinus rhythm. Our study found that using 70% ethanol injections in a systematic surgical approach is a reliable, safe, and reproducible way of creating a complete AVB model in rats.

Ischemia/reperfusion injury in male guinea pigs: An efficient model to investigate myocardial damage in cardiovascular complications

Myocardial ischemia/reperfusion (I/R) injury is the major problem that aggravates cardiac damage. Several established animal models fail to explain the similarity in disease mechanism and progression as seen in humans; whereas guinea pig shows high similarity in cardiovascular parameters. Hence, current study is aimed to develop an animal model using guinea pigs that may best correlate with disease mechanism of human myocardial I/R injury. Male guinea pigs were randomized into three groups: normal diet (ND), high fat diet (HFD) and sham; fed with respective diets for 90 days. Myocardial infarction (MI) was induced by ligating left anterior descending artery (LAD) for 30 min followed by 24 h and 7 days of reperfusion in ND and HFD groups. Electrocardiogram (ECG) showed the alterations in electrical conduction during myocardial I/R injury. Elevated levels of lactate dehydrogenase (LDH) and creatine kinase-MB ((CK-MB)) were higher in HFD compared to ND. Inflammatory markers such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were up-regulated in I/R injury animals compared to sham. Fold change of these protein expression levels were higher in HFD compared to ND. Elevated lipid profile and increased aortic wall thickness in HFD animals depicts the risk of developing cardiovascular complications. ECG analysis strongly confirmed MI through changes in sinus rhythm that are reflected in infarcted tissue as verified through TTC staining. Thus the combination of HFD followed by I/R injury proved to be an efficient model to study pathophysiology of myocardial I/R injury with minimal tissue damage and surgical mortality.

The impacts of age and frailty on heart rate and sinoatrial node function.

Sinoatrial node (SAN) function declines with age; however, not all individuals age at the same rate and health status can vary from fit to frail. Frailty was quantified in young and aged mice using a non-invasive frailty index so that the impacts of age and frailty on heart rate and SAN function could be assessed. SAN function was impaired in aged mice due to alterations in electrical conduction, changes in SAN action potential morphology and fibrosis in the SAN. Changes in SAN function, electrical conduction, action potential morphology and fibrosis were correlated with, and graded by, frailty. This study shows that mice of the same chronological age have quantifiable differences in health status that impact heart rate and SAN function and that these differences in health status can be identified using our frailty index. Sinoatrial node (SAN) dysfunction increases with age, although not all older adults are affected in the same way. This is because people age at different rates and individuals of the same chronological age vary in health status from very fit to very frail. Our objective was to determine the impacts of age and frailty on heart rate (HR) and SAN function using a new model of frailty in ageing mice. Frailty, which was quantified in young and aged mice using a frailty index (FI), was greater in aged vs. young mice. Intracardiac electrophysiology demonstrated that HR was reduced whereas SAN recovery time (SNRT) was prolonged in aged mice; however, both parameters showed heteroscedasticity suggesting differences in health status among mice of similar chronological age. Consistent with this, HR and corrected SNRT were correlated with, and graded by, FI score. Optical mapping of the SAN demonstrated that conduction velocity (CV) was reduced in aged hearts in association with reductions in diastolic depolarization (DD) slope and action potential (AP) duration. In agreement with in vivo results, SAN CV, DD slope and AP durations all correlated with FI score. Finally, SAN dysfunction in aged mice was associated with increased interstitial fibrosis and alterations in expression of matrix metalloproteinases, which also correlated with frailty. These findings demonstrate that age-related SAN dysfunction occurs in association with electrical and structural remodelling and that frailty is a critical determinant of health status of similarly aged animals that correlates with changes in HR and SAN function.

Oxidant stress derails the cardiac connexon connection

Connexin 43 (Cx43) is the major protein component of gap junctions that electrically couple cardiomyocytes at the intercalated disc. Oxidant stress, reduced Cx43 expression, and altered subcellular localization are present in many forms of structural heart disease. These changes in Cx43 lead to alterations in electrical conduction in the ventricle and predispose to lethal cardiac arrhythmias. In their study in this issue of the JCI, Smyth et al. tested the hypothesis that oxidant stress perturbs connexon forward trafficking along microtubules to gap junctions (see the related article beginning on page 266). Failing human ventricular myocardium exhibited a reduction in Cx43 and the microtubule-capping protein EB1 at intercalated discs. Oxidant stress in the adult mouse heart reduced N-cadherin, EB1, and Cx43 colocalization. In HeLa cells and neonatal mouse ventricular myocytes, peroxide exposure displaced EB1 from the plus ends of microtubules and altered microtubule dynamics. Mutational disruption of the EB1-tubulin interaction mimicked the effects of oxidant stress, including a reduction in surface Cx43 expression. These data provide important new molecular insights into the regulation of Cx43 at gap junctions and may identify targets for preservation of cellular coupling in the diseased heart.

Following ionic activity by electrochemistry during the polymerase chain reaction

The most commonly used technique for gene detection is the polymerase chain reaction (PCR). PCR is associated with alterations in ionic activity because inorganic pyrophosphate (PPi) and inorganic phosphate (Pi) ions are produced during nucleotide polymerization. To maintain electro-neutrality, magnesium, potassium, and ammonium ions are bound to DNA. Deoxynucleotides are also bound to DNA during PCR. Some authors have described DNA itself as an electrically conducting polymer formed by base stapling with the formation of extensive Pi systems. In the current study, alterations in electrical conductivity determined experimentally during PCR are reported, and a model explaining the observed changes is described. During recent years, several different techniques for quantifying PCR products have been developed. The most frequently used technique is comparison of the densitometric intensities of ethidium bromide-stained PCR products separated by electrophoresis on gels. Here an alternative technique for quantifying PCR products by measuring alterations in electrical conductivity during PCR is presented.

Image-guided Percutaneous Chemical and Radiofrequency Tumor Ablation in an Animal Model

To determine whether combining acetic acid instillation before radiofrequency (RF) ablation can improve local tissue electrical conductivity, RF energy deposition, intratumoral heating, and tumor necrosis in a large animal model. Multiple hypovascular canine venereal sarcomas were implanted in 11 mildly immunosuppressed dogs (25 mg/kg cyclosporin A twice daily). Tumors were incubated for 8-12 weeks to 4.2 cm +/- 0.6 in diameter. Treatment strategies included 10% and 15% acetic acid diluted in distilled water, 10% and 15% acetic acid diluted in saturated NaCl solution, 50% acetic acid, and 100% ethanol, with 6 mL of each injected alone or in combination with RF ablation (internally cooled, 1-cm tip; 12 minutes). Two additional control groups were studied in which tumors received either RF alone or distilled water injected alone. Comparisons were also made with groups treated with 36% NaCl with and without RF ablation. Resultant coagulation for these ablative strategies, along with local temperatures and RF parameters such as impedance, current, and power, were compared. Increasing coagulation was observed with increasing acetic acid concentrations (1.7 cm +/- 0.4, 2.8 cm +/- 0.6, and 3.5 cm +/- 0.3 for 10%, 15%, and 50% acetic acid alone, respectively; P <.01). The combination of RF ablation with acetic acid resulted in greater coagulation than with either therapy alone (P <.05). However, maximum heating and coagulation were observed with 10% acetic acid diluted in NaCl, with which the entire tumor (diameter, 4.5 cm +/- 0.4) was completely ablated in every case. This was equivalent to results for tumors treated with 36% NaCl combined with RF. RF with a 50% acetic acid concentration resulted in coagulation measuring only 3.7 cm +/- 0.3 (P <.01). Significantly greater RF heating (89.7 degrees C +/- 12.3 at 10 mm) was observed when the tumors were pretreated with 10% or 15% acetic acid in saturated NaCl, compared with 67.9 degrees C +/- 13.7 observed when acetic acid was diluted in water (P <.02). RF combined with ethanol produced less coagulation (2.8 cm +/- 0.3) than combinations with acetic acid because rapid and irreversible impedance increases were observed. Addition of acetic acid injections to RF ablation substantially increases tumor destruction compared with RF or injection therapy alone. However, lower acetic acid concentrations in saturated NaCl produced greater tumor coagulation, suggesting that, in this hypovascular tumor model, alterations in electrical conductivity play a more important role in increasing tumor ablation efficiency than do the additional ablative effects of acetic acid.

Electrical conduction within the cerebrovasculature of stroke-prone spontaneously hypertensive rats

Alterations in electrical conductivity between smooth muscle cells (SMCs) can alter the spread and effectiveness of electromechanical SMC contraction. We attempted to determine whether alterations in pressure-dependent constriction (PDC) occurring in relation to stroke development within the middle cerebral arteries (MCAs) of Wistar-Kyoto stroke-prone hypertensive rats (SHRsp) were associated with changes in electrical conductivity between the SMCs. Current was injected into nonpressurized MCAs, using a suction electrode. The conducting distance along the length of the MCA where the amplitude of the membrane potential deflection (electronic potential) produced by current injection declined to 1/e (length constant) was used to measure conductivity. PDC to a 100 mmHg pressure step was measured with a pressure myograph. A loss of PDC in the MCAs of SHRsp preceded stroke development. Heptanol (4 mM), a gap junction communication inhibitor, reversibly inhibited conductivity and PDC in the MCA of prestroke SHRsp. The ability of heptanol to reversibly inhibit PDC was likely not related to it's ability to alter electrical conduction. The length constant of electrical conduction in the MCAs was about 0.75 mm and didn't differ between MCA sampled from pre-versus post-stroke SHRsp or Sprague-Dawley rats. It was concluded that alterations in electrical conductivity along the MCA could modify the spread of PDC, but such changes do not contribute to the loss of PDC within the MCA of poststroke SHRsp.

Osmolarity in the normal state and following acetazolamide.

Investigations of the normal osmolar relationship between aqueous and plasma have demonstrated an aqueous osmolar excess in several mammalian species.^8,17,24,25This excess is considered to be the dominant driving force in aqueous humor formation.^1,16,19As acetazolamide significantly decreases the aqueous flow rate,^4-6,21an alteration in the aqueous-to-plasma osmolar relationship might reasonably be expected following the administration of the drug. Urrets-Zavalia and Remedi²⁷have demonstrated a lowering of the osmolar concentration in the dog aqueous following administration of acetazolamide, on the basis of alterations in electrical conductivity. However, no associated plasma values are reported. The present investigation has been undertaken as a further study of the aqueous-to-plasma osmolar relationship. <h3>Method</h3> Adult male albino rabbits weighing from 2.5 to 3.5 kg. were utilized, and each eye was used only once for aqueous puncture. They were allowed food (Wayne Rabbit Pellets) and water without restriction. Twenty-four hours before use