Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor.

Quasi-bound state in the continuum (QBIC) can effectively enhance the interaction of terahertz (THz) wave with matter due to the tunable high-Q property, which has a strong potential application in the detection of low-concentration biological samples in the THz band. In this paper, a novel THz metamaterial sensor with a double-chain-separated resonant cavity structure based on QBIC is designed and fabricated. The process of excitation of the QBIC mode is verified and the structural parameters are optimized after considering the ohmic loss by simulations. The simulated refractive index sensitivity of the sensor is up to 544 GHz/RIU, much higher than those of recently reported THz metamaterial sensors. The sensitivity of the proposed metamaterial sensor is confirmed in an experiment by detecting low-concentration lithium citrate (LC) and bovine serum albumin (BSA) solutions. The limits of detection (LoDs) are obtained to be 0.0025 mg/mL (12 µM) for LC and 0.03125 mg/mL (0.47 µM) for BSA, respectively, both of which excel over most of the reported results in previous studies. These results indicate that the proposed THz metamaterial sensor has excellent sensing performances and can well be applied to the detection of low-concentration biological samples.

Effect of Lithium Preparations on Cerebral Electrophysiological Activity in Rats.

The study examined the effects of a novel neurotropic medication based on a lithium complex composed of lithium citrate, polymethylsiloxane, and aluminum oxide on electrophysiological parameters of the rat brain. In contrast to lithium carbonate (the reference drug), the novel preparation resulted in a wave-like dynamics of electrical activity in the visual cortex. Rhythmic photic stimulation of the rats treated with lithium carbonate resulted in appearance of the signs attesting to up-regulation of excitability of cerebral cortex in all examined ranges. In contrast, the complex lithium preparation diminished the delta power spectrum, which was the only affected frequency band. It is hypothesized that the complex lithium medication induces milder activation of the cerebral cortex in comparison with lithium carbonate. The novel medication composed of lithium citrate, aluminum oxide, and polymethylsiloxane, is characterized by greater efficacy and safety than the preparation based on inorganic lithium salt (lithium carbonate).

Lithium Citrate Triggered Macroscopic Superlubricity with Near-Zero Wear on an Amorphous Carbon Film.

An amorphous carbon (a-C) film shows substantial potential for friction and wear reduction. In this work, the robust superlubricity state with a coefficient of friction of 0.002 at the maximal pressure of 1.15 GPa was realized when lithium citrate (LC) was applied as the lubricating additive in ethylene glycol (EG) to lubricate the Si3N4/a-C friction pair based on the ball-on-plate friction test. The wear rate of the a-C film was 4.5 × 10-10 mm3/N·m, which was reduced by 98.3% compared to that of the film lubricated with EG. Friction promoted the chemisorption of the LC molecules via the tribochemical reaction between the carboxylate radicals and the a-C film. The exposed lithium ions could adsorb water molecules to form a hydration layer, providing extremely low shear strength. Furthermore, the colloidal silica layer formed on the Si3N4 ball via the tribochemical reaction could reduce friction. It was difficult to destroy the formed tribochemical films under high contact pressure because they were robust, preventing the direct contact of the friction pair and resulting in the near-zero wear of the a-C film.

Terahertz spectroscopy detection of lithium citrate tetrahydrate and its dehydration kinetics.

Lithium citrate (LC) as a common food additive and also a psychiatric drug, usually in the form of tetrahydrate can gradually lose its crystalline water and convert into LC anhydrate at temperatures higher than the room temperature. In order to quickly distinguish the tetrahydrate from the anhydrate and to study the dehydration kinetics of the LC hydrates under the influence of the temperature, terahertz time-domain spectroscopy (THz-TDS) is utilized in this work. Experimental results show that the LC tetrahydrate at room temperature has an obvious absorption peak around 1.66 THz, while the LC anhydrate has no absorption peak at 0.5-3.0 THz. The absorption peak intensity of the LC tetrahydrate decreases continuously upon heating from 25 to 100 °C. Based on the normalized absorption peak area of the LC tetrahydrate around 1.66 THz, variation of its dehydration rate with the heating temperature is investigated and their relationship is fitted by the Arrhenius equation. The reaction activation energy of the LC tetrahydrate is derived to be 495.1 ±â€¯17.8 J/g with a deviation of about 3.7% from the traditional difference scanning calorimetry (DSC) measurement. These results indicate that THz-TDS can provide an efficient method to detect crystalline hydrates and can be applied to study the dehydration kinetics of crystalline hydrates with advantages of being fast, label-free and accurate.

Contact varroacidal efficacy of lithium citrate and its influence on viral loads, immune parameters and oxidative stress of honey bees in a field experiment.

With an almost global distribution, Varroa destuctor is the leading cause of weakening and loss of honey bee colonies. New substances are constantly being tested in order to find those that will exhibit high anti-Varroa efficacy at low doses/concentrations, without unwanted effects on bees. Lithium (Li) salts stood out as candidates based on previous research. The aims of this study were to evaluate Li citrate hydrate (Li-cit) for its contact efficacy against Varroa, but also the effect of Li-cit on honey bees by estimating loads of honey bee viruses, expression levels of immune-related genes and genes for antioxidative enzymes and oxidative stress parameters on two sampling occasions, before the treatment and after the treatment. Our experiment was performed on four groups, each consisting of seven colonies. Two groups were treated with the test compound, one receiving 5 mM and the other 10 mM of Li-cit; the third received oxalic acid treatment (OA group) and served as positive control, and the fourth was negative control (C group), treated with 50% w/v pure sucrose-water syrup. Single trickling treatment was applied in all groups. Both tested concentrations of Li-cit, 5 and 10 mM, expressed high varroacidal efficacy, 96.85% and 96.80%, respectively. Load of Chronic Bee Paralysis Virus significantly decreased (p < 0.01) after the treatment in group treated with 5 mM of Li-cit. In OA group, loads of Acute Bee Paralysis Virus and Deformed Wing Virus significantly (p < 0.05) increased, and in C group, loads of all viruses significantly (p < 0.01 or p < 0.001) increased. Transcript levels of genes for abaecin, apidaecin, defensin and vitellogenin were significantly higher (p < 0.05-p < 0.001), while all oxidative stress parameters were significantly lower (p < 0.05-p < 0.001) after the treatment in both groups treated with Li-cit. All presented results along with easy application indicate benefits of topical Li-cit treatment and complete the mosaic of evidence on the advantages of this salt in the control of Varroa.

The influence of Li+ ions on pepsin and trypsin activity in vitro.

BACKGROUND: The paper presents a study on the influence of different lithium carbonate and lithium citrate concentration on proteolytic enzymes, namely pepsin and trypsin, in vitro. Lithium can directly affect enzyme activity. Its influence on many bodily functions in both ill and healthy people has been proven. METHODS: To assess the influence of Li+ ions concentration and the substrate/enzyme ratio on pepsin and trypsin activity in vitro, 60 factorial experiments were conducted (each repeated 30 times). MAIN FINDINGS: For both enzymes, statistically significant changes in their activity under the influence of lihium carbonate and lithium citrate were observed. The biggest increase in enzyme activity reached even 198.6 % and the largest decrease in enzyme activity reached about 50 %. CONCLUSIONS: The study shows that both organic and inorganic forms of lithium salts cause changes in the activity of digestive enzymes. Different concentrations of lithium carbonate and lithium citrate stimulate or inhibit the activity of trypsin and pepsin.

Undetectable serum lithium concentrations after coadministration of liquid lithium citrate and apple juice: A case report.

Lithium is a mood-stabilizing medication approved by the FDA for the treatment of acute manic or mixed episodes of bipolar disorder as well as maintenance treatment. Lithium citrate is an oral solution, and the carbonate salt is available as oral capsules or extended-release tablets. A patient with a psychiatric history of PTSD and schizoaffective disorder-bipolar type, maintained on lithium and olanzapine prior to admission, was admitted to an inpatient psychiatric unit due to destabilization, paranoia, and mania. He was started on lithium citrate, administered with apple juice, while admitted due to nonadherence. An initial serum lithium concentration was found to be undetectable. Lithium was then administered with an alternative non-apple juice liquid, at which point serum lithium concentration became detectable and patient clinically improved. Lithium concentrations may be impacted by a number of causes, such as underlying medical conditions, drug interactions, and diet. As the majority of these factors remained stable during the patient's admission and the serum lithium concentration became detectable after switching from apple juice to an alternative non-apple juice liquid, it led to the identification of a possible incompatibility.