Qb Lu

Qb Lu
University of Waterloo | UWaterloo · Department of Physics and Astronomy

About

45
Publications
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1,340
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Publications

Publications (45)
Article
This paper reveals a large and all-season ozone hole in the lower stratosphere over the tropics (30°N–30°S) existing since the 1980s, where an O 3 hole is defined as an area of O 3 loss larger than 25% compared with the undisturbed atmosphere. The depth of this tropical O 3 hole is comparable to that of the well-known springtime Antarctic O 3 hole,...
Preprint
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Time-series observations of global lower stratospheric temperature (GLST), global land surface air temperature (LSAT), global mean surface temperature (GMST), sea ice extent (SIE) and snow cover extent (SCE), together with observations reported in Paper I, combined with theoretical calculations of GLSTs and GMSTs, have provided strong evidence that...
Preprint
Full-text available
This paper reveals a new ozone hole that exists in the lower stratosphere over the tropics (30degN-30degS) across the seasons since the 1980s, where an ozone hole is defined as an area of ozone loss larger than 25% compared with the undisturbed atmosphere. The depth of this all-season tropical ozone hole is comparable to that of the well-known spri...
Preprint
Full-text available
This paper reveals a new ozone hole that exists in the lower stratosphere over the tropics (30°N-30°S) across the seasons since the 1980s, where an ozone hole is defined as an area of ozone loss larger than 25% compared with the undisturbed atmosphere. The depth of this all-season tropical ozone hole is comparable to that of the well-known springti...
Article
There is long research interest in electron-induced reactions of halogenated molecules. It has been two decades since the cosmic-ray (CR) driven electron-induced reaction (CRE) mechanism for the ozone hole formation was proposed. The derived CRE equation with the stratospheric equivalent chlorine level and CR intensity as the only two variables has...
Preprint
Full-text available
It has been two decades since the cosmic-ray-driven electron-induced reaction (CRE) mechanism for the formation of the ozone hole was proposed. The derived CRE equation with stratospheric equivalent chlorine level and CR intensity as only two variables has well reproduced all observed data of stratospheric O3 and temperatures over the past 40 years...
Article
Full-text available
Cisplatin is the first and most widely used platinum-based chemotherapy drug and is the cornerstone agent in treating a broad spectrum of cancers. However, its clinical application is often limited by severe toxic side effects and drug resistance. Based on the discovered dissociative electron transfer mechanism of cisplatin, a novel combination of...
Article
Full-text available
There is no vaccine or specific antiviral treatment for COVID-19, which is causing a global pandemic. One current focus is drug repurposing research, but those drugs have limited therapeutic efficacies and known adverse effects. The pathology of COVID-19 is essentially unknown. Without this understanding, it is challenging to discover a successful...
Preprint
Coronavirus disease 2019 (Covid19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-stranded RNA virus. There is an ongoing global pandemic. While most of cases result in mild symptoms including fever, cough, and shortness of breath, some deaths are caused due to pneumonia and multi-organ fai...
Article
Photodynamic therapy (PDT) and photothermal therapy (PTT) are emerging modalities for the treatment of tumors and non‐malignant conditions, based on the use of photosensitizers to generate singlet oxygen or heat, respectively, upon light (laser) irradiation. They have potential advantages over conventional treatments, being minimally‐invasive with...
Article
Full-text available
Background: Pancreatic ductal adenocarcinoma (PDAC) is highly resistant to standard chemo- and radiotherapy. Recently, a new class of non-platinum-based halogenated molecules (called FMD compounds) was discovered that selectively kills cancer cells. Here, we investigate the potential of 1,2-Diamino-4,5-dibromobenzene (2Br-DAB) in combination with s...
Article
Full-text available
An electrochemical approach was devised for detecting DNA damage and differentiating two DNA damage mechanisms, which is important to the design of new chemotherapeutics. This approach combined two platforms, based on the detection of base damage and DNA strand cleavage. In this work, our approach was demonstrated for the detection of cisplatin-ind...
Article
Full-text available
Indocyanine green (ICG) has been reported as a potential near-infrared (NIR) photosensitizer for photodynamic therapy (PDT) of cancer. However the application of ICG-mediated PDT is both intrinsically and physiologically limited. Here we report a combination of ICG-PDT with a chemotherapy drug etoposide (VP-16), aiming to enhance the anticancer eff...
Article
Squaric acid and its derivatives are versatile synthons and have demonstrated applications in medicinal chemistry, notably as non-classical biosisosteric replacements for functional groups such as carboxylic acids, alpha-amino acids, urea, guanidine, peptide bonds and phosphate/pyrophosphate linkages. Surprisingly, no reports have appeared concerni...
Article
There is a compelling need to develop anti-cancer therapies that target cancer cells and tissues. Arising from innovative femtomedicine studies, a new class of non-platinum-based halogenated molecules (called FMD molecules) that selectively kill cancer cells and protect normal cells in treatments of multiple cancers have been discovered. This paper...
Article
Full-text available
Based on a molecular-mechanism-based anticancer drug discovery program enabled by an innovative femtomedicine approach, we have found a previously unknown class of non-platinum-based halogenated molecules (called FMD compounds) as potent antitumor agents for effective treatment of cancers. Here, we present in vitro and in vivo studies of the compou...
Article
In their Comment, Muller and Grooss continuously use problematic "observed data" and misleading arguments to make a case against our CRE mechanism of the ozone hole and CFC-warming mechanism of global climate change. They make the groundless assertion that the CRE theory cannot be considered as an independent process for ozone loss in the polar str...
Article
Two-photon activated photodynamic therapy (2-γ PDT) has the potential of treating deeper tumors and/or improving tumor targeting. Here, we evaluated the one- and two-photon activated PDT efficacy of pyropheophorbide-a methyl ester (MPPa), a second-generation photosensitizer derived from chlorophyll a. We show that MPPa, when activated by femtosecon...
Article
Full-text available
Clinical trials have shown that antioxidant supplementation increased the risk of lung and skin cancers, but the underlying molecular mechanism is unknown. Here, we show that epigallocatechin gallate (EGCG) as an exemplary antioxidant induced significant death and DNA damage in human lung and skin normal cells through a reductive mechanism. Our res...
Article
This study is focused on the effects of cosmic rays (solar activity) and halogenated molecules (mainly chlorofluorocarbons-CFCs) on atmospheric O3 depletion and global climate change. Brief reviews are first given on the cosmic-ray-driven electron-induced-reaction (CRE) theory for O3 depletion and the warming theory of CFCs for climate change. Then...
Article
Numerous laboratory measurements have provided a sound physical basis for the cosmic-ray driven electron-induced reaction (CRE) mechanism of halogen-containing molecules for the ozone hole. And observed spatial and time correlations between polar ozone loss or stratospheric cooling and cosmic rays have shown strong evidence of the CRE mechanism [Q....
Article
Full-text available
The platinum-based chemotherapy is the standard treatment for several types of cancer. However, cancer cells often become refractory with time and most patients with serious cancers die of drug resistance. Recently, we have discovered a unique dissociative electron-transfer mechanism of action of cisplatin, the first and most widely used platinum-b...
Article
Both water and electron-transfer reactions play important roles in chemistry, physics, biology, and the environment. Oxidative DNA damage is a well-known mechanism, whereas the relative role of reductive DNA damage is unknown. The prehydrated electron (e(pre)-), a novel species of electrons in water, is a fascinating species due to its fundamental...
Article
A Reply to the Comment by M. Alvarez-Madrigal.
Article
The 5-halo-2'-deoxyuridines bromodeoxyuridine (BrdU) and iododeoxyuridine (IdU) are well-known photosensitizers for inducing DNA/RNA-protein cross-linking and potential radiosensitizers for radiotherapy of cancer. The dependence of the photosensitivity of BrdU and IdU on the DNA sequence has been well-observed, but it is unknown whether there is a...
Article
The subpicosecond-lived prehydrated electron (e(pre)(-)) is a fascinating species in radiation biology and radiotherapy of cancer. Using femtosecond time-resolved laser spectroscopy, we have recently resolved that e(pre)(-) states are electronically excited states and have lifetimes of approximately 180 fs and approximately 550 fs, after the identi...
Article
The cosmic-ray-driven electron-induced reaction of halogenated molecules adsorbed on ice surfaces has been proposed as a new mechanism for the formation of the polar ozone hole. Here, experimental findings of dissociative electron transfer reactions of halogenated molecules on ice surfaces in electron stimulated desorption, electron trapping and fe...
Article
DNA damage is a central mechanism in the pathogenesis and treatment of human diseases, notably cancer. Little is known about reductive DNA damage in causing genetic mutations during oncogenesis and killing cancer cells during radiotherapy. The prehydrated electron (e(-)(pre)) has the highest yield among all the radicals generated in cells during io...
Article
This Letter reports reliable satellite data in the period of 1980-2007 covering two full 11-yr cosmic ray (CR) cycles, clearly showing the correlation between CRs and ozone depletion, especially the polar ozone loss (hole) over Antarctica. The results provide strong evidence of the physical mechanism that the CR-driven electron-induced reaction of...
Article
Despite intense study over the past two decades, the dynamics of electron solvation in water, particularly regarding the physical properties and lifetimes of non-equilibrium, incompletely relaxed electrons, remain very controversial. Both experimental and theoretical studies have reported a very diverse range, from approximately 50 to approximately...
Article
In our recent paper [J. Chem. Phys.128, 041102 (2008)], we reported a femtosecond time-resolved laser spectroscopic study of the electron transfer reaction of CCl(4) in liquid ethanol. Our results provide direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated electron to CCl(4), and indicate that RDET can be an eff...
Article
Diamond-like amorphous carbon films have been deposited on silicon and quartz substrates by ablation of graphite using 120 fs pulses from an amplified Ti:sapphire laser operating at 800 nm. The results clearly show that fs-DLC films are composed of sp, in addition to sp2 and sp3 bonded species. We find that the sp concentration can be somewhat incr...
Article
We report a pump-probe femtosecond transient absorption spectroscopic study on the electron transfer reaction of CCl(4) in liquid ethanol. By direct observations of the presolvated electron and of the reaction transition state CCl(4) (*-), this study provides direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated e...
Article
Diamondlike amorphous carbon films have been deposited on silicon and quartz substrates by laser ablation of graphite using 120 fs pulses from an amplified Ti:sapphire laser operating at 800 nm. Ultraviolet/visible (UV/VIS) and micro-Raman spectra of these materials have shown that the sp3-bonded carbon fraction in these films is ≈27%, 55%, and 20%...
Article
Full-text available
The growth, surface morphology, and electronic binding states of diamondlike films deposited by femtosecond laser ablation on Si wafers at 77 K have been studied in order to elucidate the mechanical properties of this material. Nanoscale buckling has been observed and is found to have a morphology that exhibits a strong dependence on film thickness...
Article
Full-text available
Microscopic phase transformation from graphite to sp-bonded carbon chains (carbyne) and nanodiamond has been induced by femtosecond laser pulses on graphite surface. UV/surface enhanced Raman scattering spectra and x-ray photoelectron spectra displayed the local synthesis of carbyne in the melt zone while nanocrystalline diamond and trans-polyacety...
Article
Life's not too short: 5‐Halo‐2′‐deoxyuridines (XdUs) have been tested as hypoxic radiosensitizers in cancer therapy, but their molecular reaction mechanism is poorly understood. Time‐resolved femtosecond laser spectroscopic measurements show that dissociative attachment of prehydrated electrons (epre−) to XdUs is responsible for the formation of a...
Article
The cytotoxicity of cisplatin as a very effective chemotherapeutic anticancer drug is known to arise from its capacity to damage DNA. However, the mechanism of action of cisplatin at the molecular level, in particular, the reaction dynamics of cisplatin with DNA, remains elusive, and the reason why cisplatin binds to the guanine bases rather than t...
Article
Combination of low-dose cisplatin with radiotherapy or photodynamic therapy (PDT) is a novel cancer treatment. Using time-resolved femtosecond laser spectroscopy, we reveal the molecular mechanisms of the combinations of cisplatin with radiotherapy and PDT using indocyanine green (ICG) excited at 800 nm. DNA damage measurements confirm that electro...
Article
A comparative study of carbon bonding states and Raman spectra is reported for amorphous diamondlike carbon films deposited using 120 fs and 30 ns pulsed laser ablation of graphite. The presence of sp(1) chains in femtosecond carbon films is confirmed by the appearance of a broad excitation band at 2000-2200 cm(-1) in UV-Raman spectra. Analysis of...
Article
Replacement of thymidine in DNA by bromodeoxyuridine (BrdU) has long been known to enhance DNA damage and cell death induced by ionizing/UV radiation, but the mechanism of action of BrdU at the molecular level is poor understood. Using time-resolved femtosecond laser spectroscopy, we obtain the real-time observation of the transition state of the u...
Article
Femtosecond transient absorption measurements were carried out to investigate the scavenging effect, at low concentration, of the radiosensitizing molecule 5-bromo-2‘-deoxyuridine (BrdU) on presolvation states of the hydrated electron. Hydrated electrons were generated by two photon absorption of bulk water at 267 nm, and transient absorption at 12...
Article
A recent observation strikingly showed that global warming from 1950 to 2000 was most likely caused by the significant increase of chlorofluorocarbons (CFCs) in the Earth atmosphere (Lu, 2010). Here, three key questions are addressed: (1) How could CO 2 play a negligible role in recent global warming in view of its extremely high concentrations of...

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