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Laser Photocoagulation Principles
Published in John P. Papp, Endoscopie Control of Gastrointestinal Hemorrhage, 2019
where h is Plack’s constant, c is the speed of light, and ≈ is the wavelength. Thus, light of a particular wavelength may be viewed as a collection of photons of equal energy. By carefully noting (using absorption spectroscopy) which energy of photons are absorbed by a particular atom, the chemist is able to identify the atom under scrutiny because its “signature” is known. Likewise, the photons which an atom is capable of emitting are energetically related to its own particular quantum levels or energies. Spectroscopy which uses the emission signature of an atom is referred to as emission spectroscopy. Sometimes the emission is forced using a spark or flame in an atmosphere of the atom being tested. The emission of light by an atom can occur at any time provided it has a lower energy state which nature allows for it. The fact that the emission can occur at any time means that the scientist must use a statistical estimate of the likelihood of emission, rather than an absolute prediction of the occurrence. This kind of statistical emission is referred to as “spontaneous emission”.
Considering Tin as a Vital Nutrient
Published in Nate F. Cardarelli, Tin as a Vital Nutrient:, 2019
Difficulties encountered in analysis of tin content in human and other tissue, especially regarding data based upon emission spectroscopy, would indicate that probable error is towards the conservative side. There is no reasonable doubt that tin is ubiquitous in the environment and widely dispersed through mammalian tissues. The discrepancies, and they are many, noted among investigators are not in regard to the presence of tin, but rather as to the quantities reported.
Light, Matter, and Spectroscopy
Published in Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk, Survival Guide to General Chemistry, 2019
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk
An electron can emit one photon to move from an initial higher electron energy level to a final lower energy level. Emission spectroscopy measures the wavelengths of light photons that are emitted during electron transitions in an atom. The electron(s) in the atom reach a higher energy level through other added energy such as heat or electricity. The emitted photon wavelengths (colors, if in the visible region of the spectrum) appear as bright (colored) lines against a dark background of all other non-emitted wavelengths of light.
Tachyplesin I and its derivatives: A pharmaco-chemical perspective on their antimicrobial and antitumor potential
Published in Expert Opinion on Drug Discovery, 2022
Shengxin Lu, Jiayi Lin, Jinmei Jin, Lijun Zhang, Yingyun Guan, Hongzhuan Chen, Ye Wu, Weidong Zhang, Xin Luan
The Trp has fluorescence emission property, and its emission maximum value can be shifted depending on the surrounding environment [100]. The Trp fluorescence emission spectroscopy has widely used to examine the interaction between peptides and model lipid bilayers [101-103]. Researchers observed a blue shift of the maximum when TPI was incubated with tumor model membrane, which indicated that TPI could successfully penetrate into it. They also measured the penetration depth of Trp of TPI into the lipid membranes [22]. Acrylamide could quench the fluorescence of Trp in aqueous solution but could not affect the fluorescence of Trp already inserted into the lipid bilayer. The fluorescence quenching result indicated that after incubation with neutral membrane and tumor model membrane, TPI lost 90.5% and 16.2% of Trp residue fluorescence, respectively. Using lipidic quenchers 5- and 16-doxyl stearic acids to test the quenching efficiency of fluorescence on the membranes, it was found that 16DS had a higher quenching efficiency, which demonstrated that the Trp of TPI could be deeply inserted into the hydrophobic core of tumor membrane mimic bilayer. In the study of Ding et al., they found that TPI could inhibit the growth of glioma stem cells (GSCs) at concentrations (≈17.7–35.3 μM), disrupting the plasma membrane and leading to the loss of massive organelles in tumor cells. At the higher concentrations (≈70 μM), TPI could directly induce cancer cell death [23]. Thus, the disruption of membrane is one of the most important mechanisms for TPIs to exert the antitumor activity [Figure 4(a)].
Triumph against cancer: invading colorectal cancer with nanotechnology
Published in Expert Opinion on Drug Delivery, 2021
Preksha Vinchhi, Mayur M. Patel
Graphene oxide nano-systems possess superior mechanical and electrical properties, colloidal stability and ease of surface modification. Owing to these benefits they have received significant attention in theranostic applicability. A novel theranostic graphene oxide nanosystem conjugated with BSA, polydopamine (PDA), (DTPA-Mn-II) – a contrast agent, chemotherapeutic drug (5-FU) and targeting agent (folic acid) were formulated and evaluated. Several evaluations were done that includes: in vitro and in vivo MRI study to evaluate its diagnostic ability, inductively coupled plasma optical emission spectroscopy study to evaluate its biodistribution, histopathological tests to check the biocompatibility and in vivo study on colon cancer cell lines to evaluate its anticancer efficacy. The results demonstrated that the nanosystem was distributed particularly to the cancer cells and was highly biocompatible. The formulation also served as an excellent contrast agent for MRI as well as imparted a high therapeutic effect on cancer cells in the studies [94].
In vitro and in vivo characteristics of doxorubicin-loaded cyclodextrine-based polyester modified gadolinium oxide nanoparticles: a versatile targeted theranostic system for tumour chemotherapy and molecular resonance imaging
Published in Journal of Drug Targeting, 2020
Tohid Mortezazadeh, Elham Gholibegloo, Mehdi Khoobi, Nader Riyahi Alam, Soheila Haghgoo, Asghar Mesbahi
FTIR spectra of the prepared samples were obtained through a Fourier transform infrared spectrometer (Magna 550, Nicolet) at the wavelength range of 400–4000 cm−1. The crystal structure of Gd2O3@PCD-FA-DOX NPs was assessed by X-ray powder diffraction system (STOE Theta-Theta Powder Diffraction System). Ultraviolet visible (UV–Vis) spectra were taken using Jasco-530 spectrophotometer at the wavelength range of 220–700 nm. Elemental analysis was determined by inductively coupled atomic emission spectroscopy, ICP-AES (7900, Agilent). Hydrodynamic size distribution and zeta potential analyses were performed by Zeta-sizer (ZEN3600, Malvern) in deionised water at room temperature. Size and morphology of the dried samples were determined by field emission scanning electron microscopy, SEM (MIRAII and MIRAIII Tescan) and transmission electron microscopy, TEM (CM30, Philips) operating at 60 kV. Vibrating sample magnetometer (VSM) measurements were done by VSM, 7400 model (Lakeshore Cryotronics Inc., USA), with a maximum magnetic field of 10 kOe at 25 °C to evaluate the magnetic properties of the samples. Thermogravimetric analysis (TGA) was conducted on the dried powder samples on the TGA Q50 thermogravimetric analyser of a TA instrument from room temperature to 800 °C in a heating rate of 10 °C min−1 under N2 flow. Phantom, in vitro, and in vivo MR imaging were performed by a 3.0 T MRI clinical scanner (Siemens Prisma MRI Scanner using head coil).