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Abstract The hormetic effect may cause disease control measures to fail due to inadequate treatment of human disease vectors such as houseflies. Age-stage, two-sex life table is used for accurate estimation of the hermetic impacts on insects as it allows to study sub-lethal or transgenerational effects. Pyrethroids insecticides are primarily used for the management of houseflies. This study used lambda-cyhalothrin (a pyrethroid insecticide) to quantify its transgenerational impacts on houseflies. Life table parameters of a progeny of adult houseflies exposed to LC10, LC30, and LC50 of lambda-cyhalothrin were computed. Statistically higher fecundity (71.31 per female) was observed in control treatment, while it was the adults exposed to LC50 recorded the lowest progeny. Significantly higher values for intrinsic rate of growth (r), limiting rate of growth (λ), and net reproductive rate (R o ) (0.16, 1.16, and 31.38 per day, respectively) were recorded for the control treatment of the study. Contrarily, lower values for λ, R o, and r were (0.10, 1.10, and 9.24 per day, respectively) were noted in the LC50 treatment. Decreased population parameters suggest that lambda-cyhalothrin can be successfully used in indoor environments to control houseflies.

Stripe rust (SR) caused by Puccinia striiformis Westend. f. sp. tritici Erikss (Pst) is one of the most important and destructive disease of wheat worldwide. In Pakistan, stipe rust appeared as epidemic and is causing huge losses to wheat production. However, wheat breeding programs are not sufficiently advanced to cope with the recently emerged Puccinia striiformis strains. Under this scenario, current research was carried out for safe, effective and sustainable management of stripe rust of wheat. Seven wheat varieties include Sehar-06, Galaxy-13, Abdul Sattar-02, Faisalabad-08, Johar-16, TD-1 and Ujala-16 were planted at research farm of Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan during November 2019–20 and 2020–21 to determine their response toward Puccinia striiformis. The fungicide Tilt®, propiconazole, (T2) at the rate of 3 mL per 1500 mL water was used while the Bacillus subtilis (T1) was added at rate of 0.25 mL/1500 mL water with 15 g of dextrose, 0.25 g of chitosan and 0.25 g of salicylic acid in 1500 mL water to make a fine suspension. Our results showed that T1 reduced the disease effectively up to (8.18%) followed by T2 (10.7%) as compared to T0 (23.8%). The correlation between minimum air temperature, relative humidity and disease severity was highly significant while with maximum air temperature it was negatively non-significant. Also, wind speed, solar radiation and rainfall showed non-significant correlation with disease severity. After treatment, application of T1 and T2, minimum air temperature expressed a significant correlation with disease severity on varieties Sehar-2006, Galaxy-13 and Abdul Sattar-02 while non-significant correlation with disease severity on varieties Faisalabad-08, Johar-16, TD-1 and Ujala-16. Similarly, maximum air temperature, relative humidity, wind speed and solar radiation showed non-significant correlation with disease severity while rain fall was negatively non-significant. The current study showed that Bacillus subtilis is an ecofriendly management of stripe rust and its combination with plant defense activators enhance the efficacy and suppress disease. This management strategy is an innovative, and the results obtained will be helpful for better, ecofriendly and effective management of disease.

BACKGROUND & OBJECTIVE: Advancements in transplant regimens, alternative grafts, and new indications have improved bone marrow transplant activity with time. Our objective is to determine the pattern of pulmonary abnormalities using High resolution computed tomography (HRCT) chest scan and to determine the diagnostic accuracy (pulmonary abnormalities) and efficacy (in terms of radiation burden) of HRCT and X-rays after bone marrow transplant. METHODOLOGY: It was a descriptive case series conducted at the department of Radiology, POF Hospital, Wah Cantt over a duration of 8 months (January 2021-Augest 2021). A sample size of 20 patients was calculated using the WHO calculator. Patients were recruited through non-probability consecutive sampling. Patients were undergone through HRCT and chest X-rays for diagnostic accuracy and radiation burden measurement. Data was analyzed using SPSS version 24. Fisher exact test, Receiver Operating characteristic (ROC) Curve analysis and t-test was applied for statistical analysis. p-value ≤0.05 was considered significant. RESULTS: A total of 20 patient’s undergone bone marrow transplants were included in the study. The mean age of patients was 5. 25years.There were 11(55%) male and 9(45%) female in study. Pattern of pulmonary abnormalities was pleural effusion 2(10%) following nodules 1(5%), pneumonia patches 1(5%), ground glass opacities 1(5%) and septal thickening 1(5%). The diagnostic accuracy of HRCT was found to be high as compared to X-rays (88% vs 57% respectively). The mean radiation dose in HRCT and mean radiation dose in X-rays’ indicate a high radiation burden in HRCT (p≤0.001). CONCLUSION: Despite of high radiation burden in HRCT, it had high diagnostic accuracy as compared to X-rays.

Objective: To compare the clinical effectiveness of Paracetamol with Ibuprofen as an antipyretic, fever relief and linked discomfort in children. Study Design: Comparative cross-sectional study. Place and Duration of Study: Combined Military Hospital, Abbottabad Pakistan from Apr to Nov 2019. Methodology: Children aged six months to five years, who reported fever between 38-41°C were included. Two temperature groups were developed, i.e., 37.8–38.9ºC and 39–41ºC with baseline temperatures of 38.60±0.56 for Paracetamol-Group and 38.58± 0.56ºC for Ibuprofen-Group. The prescriptions were given over to the parents with clarification about the dose of the medication. The medication had active and placebo forms. Information was gathered until saturation was done. Results: A total of 104 children were taken in the study. Of these, 77(74.08%) were females, and 27(24.96) were males. Comparing Ibuprofen-treated children with Paracetamol-Group, the final result showed that the extent of children's temperature management was greater in the Ibuprofen-Group 37(71%) than in the Paracetamol-Group 34(65%). Conclusion: Doctors, attendants and guardians wishing to use medications to treat children suffering from fever should be encouraged to use Ibuprofen first and to consider the relative risks and advantages of using Ibuprofen in addition to Paracetamol for fever. Comparatively, Ibuprofen is more effective than Paracetamol.

Using plant extracts as eco-friendly reducing and stabilizing agents for the synthesis of nanoparticles has gained significant attention in recent years. The current study explores the green synthesis of silver nanoparticles (AgNPs) using the Avena fatua extract and evaluates their antifungal activity against Fusarium oxysporum f.sp. lycopersici (Fol), a fungal plant pathogen. A green and sustainable approach was adopted to synthesize silver nanoparticles before these nanoparticles were employed for anti-fungal activity. The primary indication that AgNPs had formed was performed using UV-vis spectroscopy, where a strong peak at 425 nm indicated the effective formation of these nanoparticles. The indication of important functional groups acting as reducing and stabilizing agents was conducted using the FTIR study. Additionally, morphological studies were executed via SEM and AFM, which assisted with more effectively analyzing AgNPs. Crystalline behavior and size were estimated using powder XRD, and it was found that AgNPs were highly crystalline, and their size ranged from 5 to 25 nm. Synthesized AgNPs exhibited significant antifungal activity against Fol at a concentration of 40 ppm. Furthermore, the inhibitory index confirmed a positive correlation between increasing AgNPs concentration and exposure duration. This study suggests that the combined phytochemical mycotoxic effect of the plant extract and the smaller size of synthesized AgNPs were responsible for the highest penetrating power to inhibit Fol growth. Moreover, this study highlights the potential of using plant extracts as reducing and capping agents for the green synthesis of AgNPs with antifungal properties. The study concludes that A. fatua extract can synthesize antifungal AgNPs as a sustainable approach with robust antifungal efficacy against Fol, underscoring their promising potential for integration into plant protection strategies.

Environmental factors (biotic and abiotic) are major depletion reasons in granaries. Fungi and insect pests act synergistically in deterioration of grains in storages which results in nutritional damage to the stored food which becomes unpalatable for the consumer. There is a need to establish a timeline for synergistic damage caused by insect pests and mycotoxigenic fungi for better management. For this purpose, interaction of mycotoxigenic fungi (Aspergillus flavus, Aspergillus niger, Penicillium digitatum and Alternaria alternata) with Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) was studied at different temperatures. Development of C. maculatus was observed on fungus inoculated and uninoculated C. arietinum seeds. In fungus inoculated grains the development (Fecundity, larval emergence, pupation rate and adult emergence) of C. maculatus was found more better as compared on uninoculated grain. The population of C. maculatus was decreased by increase in temperature but high temperatures favours more fungi developments. More egg laying was observed at 27 °C and 33 °C. At tested temperatures, larval emergence was high as compared to other observed life attributes. Infestation of A. flavus and A. niger was also increased with increase of temperatures. Penicillium digitatum and A. alternata infestation were increased in the C. arietinum at 27 °C and 30 °C respectively. This study will help in measuring the control practices of fungi and insect pest infestations in stored C. arietinum (chickpea) in Pakistan.

Natural and artificial ageing treatments are compared with ageing by cyclic deformation at room temperature. Atom probe tomography and transmission electron microscopy revealed that a fine distribution of GP-zones, was responsible for the strength after cyclic ageing. Ten days further natural ageing allowed these early-stage clusters to grow into more stable ones, thereby improving the mechanical response. This resulted in similar tensile strength and uniform elongation as for the peak aged condition by artificial ageing. It was found that fracture of cyclic aged samples occurred earlier, in the form of a ductile slant shear fracture without necking in advance. In all cases, the slant fracture started at about the same point as reaching maximum strength, i.e., at the uniform limit. However, by an artificial ageing treatment after the cyclic hardening treatment, an ordinary necking behavior was seen, similar as for the peak aged samples. Natural aged samples had similar GP-zones as the cyclic hardened ones, and the same slant fracture mode, indicating that the precipitation structure controls the fracture type. Similar behavior was observed for two different Al-Zn-Mg alloys, with and without copper.

Objective:To determine association of early-onset neonatal sepsis (EONS) in newborns of serum C-reactive protein positive mothers. Study Design: Cross sectional study Place and duration of study: Department of Pediatrics, Combined Military Hospital Quetta, Pakistan from September 2016 to March 2018. Material and Methods: 105 neonates (both gender) of all mothers who were C - reactive protein positive were enrolled in this study using inclusion and exclusion criteria.Neonatal sepsis was diagnosed by clinical examination, which was carried out by senior pediatrician, blood complete picture and c reactive protein. Neonates were treated as per departmental protocol. Stratification was done in regard to gestational age, birth weight and age of neonates in hours. Post stratification chi square test was applied and p-value less than 0.05 was considered significant. Results:Out of total 105 patients, 46 (44%) were male and 59 (56%)were female neonates. Amongst the babies of 105 CRP positive mothers, 79 babies were having signs and symptoms of neonatal sepsis and 26 babies were having no signs and symptoms of neonatal sepsis with statistically significant relation between maternal CRP and neonatal sepsis of p value

The statement of the Prophet’s (peace be upon him) message and calling towards Allah is incomplete without reviewing the causes, evolution, and consequences of the opposition of Quraysh-e-Makkah. Opposition and hatred of Quraysh have historically consisted of two stages. The first phase begins with the proclamation of Prophethood, and this phase continues in full force before the migration of Madinah. While the second period of the Quraysh began immediately after the migration of Madinah. Opposition and denying the invitation to the truth is actually a sign of truth. This is why the Prophet's Prophecy and the opposition of Quraysh are co-ordinated. The Seerah writers have mentioned in detail the events of the proclamation of Prophethood to Madinah, usually in opposition to Quraysh, but after the migration to Madinah, the review of the opposition of Quraysh along with the publication of Islam not taken. This article reviews the opposition and hostility of Quraysh in the context of the Makki and Madani Period, as well as a review of the evolution of the Prophethood, the propaganda strategy, the publication of Islam, and the efforts made for the consolidation of Islamic society in this context.

Farmers rely on chemical control for managing insect pests which cause various human and environmental health hazards. So, biopesticides like Nucleopolyhedrovirus (NPVs) can be a suitable alternative due to their less toxic effects on non-target organisms and environment. As a matter of fact, NPVs have been proven very effective against lepidopteran larvae. However, defining the host range of NPV was required according to the ecological conditions of Pakistan. So, this study was planned in which NPV isolated from Helicoverpa armigera, HaNPV, was used to infect H. armigera, Spodoptera litura, S. exigua, Pectinophora gossypiella and Trichoplusia ni under controlled conditions (temperature = 25 ± 2 °C; RH = 60 ± 5%). Higher mortality was observed in H. armigera among all the tested hosts. Additionally, mortality of all the other tested species showed no significant difference as compared to their untreated control. Similarly, a higher peak was achieved in H. armigera after two days of infection. Due to the multiplication of virions inside the host body, host tissues are destroyed. Many factors like larval body size, temperature and environmental conditions affect the rate of response and pathogenicity. Thus the pathogenicity varies with time of infection. Decrease in infection and mortality can be attributed to resistance and increase in the size of larvae with the passage of time. Non significant mortality in non-hosts species by HaNPV suggests its highly specific nature. Thus, it can be successful highly specific ecofriendly management tool for H. armigera. However, in extreme environmental conditions, NPV should be used with sunblock.

Essential oils (EOs) have received attention in the food industry for developing biopolymer-derived food packaging materials. EOs are an excellent choice to replace petroleum-derived additives in food packaging materials due to their abundance in nature, eco-friendliness, and superior antimicrobial and antioxidant attributes. Thus far, EOs have been used in cellulose-, starch-, chitosan-, and protein-based food packaging materials. Biopolymer-based materials have lower antioxidant and antibacterial properties in comparison with their counterparts, and are not suitable for food packaging applications. Various synthetic-based compounds are being used to improve the antimicrobial and antioxidant properties of biopolymers. However, natural essential oils are sustainable and non-harmful alternatives to synthetic antimicrobial and antioxidant agents for use in biopolymer-derived food packaging materials. The incorporation of EOs into the polymeric matrix affects their physicochemical properties, particularly improving their antimicrobial and antioxidant properties. EOs in the food packaging materials increase the shelf life of the packaged food, inhibit the growth of microorganisms, and provide protection against oxidation. Essential oils also influence other properties, such as tensile, barrier, and optical properties of the biopolymers. This review article gives a detailed overview of the use of EOs in biopolymer-derived food packaging materials. The innovative ways of incorporating of EOs into food packaging materials are also highlighted, and future perspectives are discussed.

Objective: To find out the association between iron deficiency anemia and febrile seizures in children. Study Design: Analytical: case-control study. Place and Duration of Study: The study was conducted at Paediatrics department, Pak Emirates Military Hospital Rawalpindi, from May 2013 till Oct 2013. Material and Methods: Two Hundred patients were selected through non probability consecutive sampling, one hundred in each group i.e. patients with febrile seizures and patients without febrile seizures. The blood sample of cases and controls were taken at the time of admission and was sent for assessment of hemoglobin (Hb), serum ferritin level, mean corpuscular hemoglobin concentration (MCHC) and mean corpuscular volume (MCV). The samples were analyzed for iron deficiency anemia and compared in both groups (patients with febrile seizures and those without febrile seizures). Results: In the febrile seizures group 58 (58%) were anemic with a hemoglobin level less than 10gm/dL and 59 (59%) had a low plasma ferritin of less than 10ng/dL. In the control group 39 (39%) were anemic with a hemoglobin level less than 10gm/dL and 26 (26%) had a plasma ferritin of less than 10ng/dL. The frequency of anemia with low MCV, MCHC and serum ferritin was more in the febrile seizure group 38% as compared to 20% in controls (p-value = 0.002). Conclusion: The children with febrile seizures have lower hemoglobin, MCV, MCHC and serum ferritin level as compared to the control groups suggesting that iron deficiency anemia has a positive role in the pathogenesis of febrile seizures.

Titanium dioxide nanoparticles (TiO2-NPs) were synthesized via a facile hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR), and Raman spectroscopy were used to study the structure, morphology, chemical composition, and functional group attached to the as-synthesized TiO2-NPs. These NPs were then used to test their efficacy against various microbes and their potency as effective catalysts. TiO2-NPs are found to have the maximum antibacterial activity against Gram-negative bacterial strains rather than Gram-positive bacteria. The photocatalytic activity of the TiO2-NPs was investigated for the photodegradation of 10 ppm bromophenol blue (BPB) dye by using 0.01 g–0.05 g of catalyst. TiO2-NPs exhibited the removal of 95% BPB, respectively, within 180 min. The TiO2-NPs’ antibacterial and catalytic properties suggest that these may be used in environmental remediation as a cost-effective and environmentally friendly wastewater and air treatment material.

Gastric volvulus is an abnormal, potentially life-threatening, torsion of the stomach. The presence of complications such as hemoperitoneum increases the diagnostic urgency; however it can also mask the presentation of gastric volvulus. We encountered a 66-year-old female who presented with symptomatic gastric outlet obstruction and was found to have hemoperitoneum and splenic avulsion on imaging. In our case, hemoperitoneum was a clinical red herring as initial imaging concentrated on the presence of hemoperitoneum and was nondiagnostic of gastric volvulus. Interestingly, our patient experienced complete resolution of her presenting symptomatology following placement of a nasogastric tube. Furthermore, endoscopic evaluation revealed no overt pathology to explain outlet obstruction. In light of these findings, gastric torsion was strongly suspected. A repeat CT scan was confirmatory, elucidated reduction of the stomach to its anatomic position, retroactively diagnosing a gastric volvulus. This case is unusual in its presentation and setting. The patient presented with two rare complications of gastric volvulus, hemoperitoneum and splenic avulsion. Additionally, ten years prior to this presentation the patient had a temporary gastrostomy tube. Gastropexy with a gastrostomy is the treatment for gastric volvulus and should have been preventative of her presentation with torsion. Furthermore, the gastric volvulus was not initially recognized radiographically due to the presence of masking radiographic findings. This case serves to highlight the utility of clinical acumen and maintain a high index of suspicion for gastric volvulus in all cases presenting with Borchardt’s triad.

We present an atypical case of newly diagnosed colon cancer and provide insight into the infectious predispositions of E. coli bacteremia to the development of colon adenocarcinoma. A 66-year-old female was admitted to the hospital with one-week symptoms of subjective fevers, chills, and lower back pain. Upon initial evaluation, her temperature was 101 degrees Fahrenheit with a white count of 12,000 K/mm3. Initial septic workup was positive for E. coli bacteremia. The patient was started on Aztreonam. Repeat blood culture 48 hours later was negative for any growth. However, later during hospital stay blood culture was repeated due to SIRS, which was positive again for E. coli. CT scan of the chest/abdomen/pelvis with contrast revealed no signs of colitis. Without clear etiology for recurrent E. coli bacteremia ultimately colonoscopy was performed which showed an ulcerated mass in the cecum. Biopsy showed moderately differentiated adenocarcinoma. E. coli strains B2 and D produce cyclomodulin toxins as part of their virulence, which interferes with the cell cycle regulation, promoting chromosomal instability, and increasing susceptibility to cancer. In patients with recurrent E. coli bacteremia with an unknown source, colonoscopy should be done to look for colon cancer.

Background Clostridioides difficile infection (CDI) is a major cause of hospital-acquired diarrhea and is associated with substantial morbidity and mortality. Recurrences following treatment are common. Fecal microbiota transplantation (FMT) is a therapeutic intervention in which stool from a healthy donor is administered to a patient with recurrent CDI. Studies to date of predictors of FMT failure have primarily included inpatients. In this study, we aimed to describe FMT failure rates within one year of FMT and evaluate factors associated with FMT failure. Methodology We conducted an exploratory retrospective study of consecutive patients who underwent outpatient FMT at a single tertiary care center in Western Massachusetts from December 2014 through September 2018. We collected patient data including demographics, CDI - related factors, and FMT-related factors. FMT failure was defined as non-response or recurrence of diarrhea, associated with positive stool C. difficile toxin or polymerase chain reaction. Unadjusted relative risk (RR) and 95% confidence intervals for factors associated with FMT failure were estimated using log-binomial regression. Results A total of 92 patients were included with a mean age of 64 years. CDI severity was mild or moderate in 73% and severe or fulminant in 27%. The most common FMT indication was recurrent CDI in 76% of patients. FMT failure occurred in 25 of 92 (27%) patients, with half occurring within 11 days. Factors associated with FMT failure were active malignancy (RR = 2.56), prior hospitalizations (RR = 2.42), and receipt of non-CDI antibiotics within six months of FMT (RR = 2.80). We did not observe strong associations for risk of FMT failure with age ≥65, sex, use of proton pump inhibitors or H2 receptor agonists, history of colectomy, immunosuppression, history of malignancy, diabetes, appendectomy, CDI severity, or probiotic use. Conclusions Active malignancy, prior CDI hospitalizations, and non-CDI antibiotics within six months before FMT were associated with FMT failure in the outpatient setting. Knowledge of the above factors may help inform shared decision-making with patients at risk for FMT failure., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Warraich et al.)

Objective: To qualitatively analyse the barriers in pursuing undergraduate research, and to propose solutions for the problems identified., Methods: The qualitative study was conducted from May to October 2021 after approval from the institutional ethics review board of the Dow University of Health Sciences, Karachi, and comprised undergraduate students of either gender at various public and private medical universities across Pakistan having some level of research experience and good communication skills. Data triangulation was employed to collect qualitative data through open-ended survey, face-to-face interviews and focus group discussions. Using the information of one method to inform the rest, linked trajectories were established that allowed validation of information at each level. Data was coded manually by two researchers independently. Data was subjected to inductive thematic analysis., Results: Of the 33 subjects, 17(51.5%) were males, 17(51.5%) were from private medical colleges, 18(54.5%) were from Karachi, and 11(33.3%) were in the final year of medical school. Overall, 13(39.4%) students completed the open-ended survey, 6(18.2%) completed face-to-face interviews, and 14(42.4%) participated in focus group discussions. Thematic analysis showed that students were interested in research to improve their career prospects, but not all were passionate about it. Students were not satisfied with the quality of research being conducted in the country. Dearth of motivated faculty, unavailability of well-maintained and digitalised data registries, ineffective research methodology teaching and lack of access to medical journals and research software were the major barriers in undergraduate research. Time constraint was a projecting problem which challenged the students. Frequent research workshops and conferences, strong networking, reorienting curriculum to provide early exposure to research and student-led initiatives were suggested to improve undergraduate research in Pakistan., Conclusions: Students' lack of initiative coupled with administrative and faculty-related issues pose a serious threat to the future of evidence-based medicine. Proposed solutions offer a ray of hope to the future of undergraduate research in Pakistan.

Background: Palliative care (PC) has been shown to be beneficial in end stage liver disease (ESLD), yet the hospitalization data for PC utilization is unknown., Aim: To identify the trend of PC utilization for the special population of alcohol-associated ESLD patients, factors affecting its use and ascertain its impact on healthcare utilization., Methods: We analyzed around 78 million discharges from the 2007-2014 national inpatient sample and 2010-2014 national readmission database including adult patients admitted for decompensated alcohol-associated cirrhosis. We identified patients with PC consultation as a secondary diagnosis. Odds ratios (OR) and means were adjusted for confounders using multivariate regression analysis models., Results: Out of the total 1421849 hospitalizations for decompensated liver cirrhosis, 62782 (4.4%) hospitalizations had a PC consult, which increased from 0.8% (1258) of all alcohol-associated ESLD hospitalizations in 2007 to 6.6% in 2014 ( P < 0.01). Patient and hospital characteristics associated with increased odds of PC utilization were advanced age, lower income, Medicaid coverage, teaching institution, urban location, length of stay > 3 d, prolonged ventilation, and administration of total parenteral nutrition (all P < 0.01). Palliative encounters in alcohol-associated ESLD and acute-on-chronic liver failure (ACLF) score were associated with increased odds of discharge to a rehabilitation facility, but significantly lower odds of 30-d readmissions (aOR: 0.35, 95%CI: 0.31-0.41), lower total hospitalization charges and lower mean hospitalization days (all P < 0.01)., Conclusion: Inpatient PC is sparingly used for patients with decompensated alcohol related liver disease, however it has increased over the past decade. PC consultation is associated with lower 30-d readmission rates on multivariate analysis, and lower hospitalization cost and length of stay in patients with ACLF score ≥ 2., Competing Interests: Conflict-of-interest statement: There are no conflicts of interest to report., (©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.)

Quantum coherences, observed as time-dependent beats in ultrafast spectroscopic experiments, arise when light-matter interactions prepare systems in superpositions of states with differing energy and fixed phase across the ensemble. Such coherences have been observed in photosynthetic systems following ultrafast laser excitation, but what these coherences imply about the underlying energy transfer dynamics remains subject to debate. Recent work showed that redox conditions tune vibronic coupling in the Fenna-Matthews-Olson (FMO) pigment-protein complex in green sulfur bacteria, raising the question of whether redox conditions may also affect the long-lived (>100 fs) quantum coherences observed in this complex. In this work, we perform ultrafast two-dimensional electronic spectroscopy measurements on the FMO complex under both oxidizing and reducing conditions. We observe that many excited-state coherences are exclusively present in reducing conditions and are absent or attenuated in oxidizing conditions. Reducing conditions mimic the natural conditions of the complex more closely. Further, the presence of these coherences correlates with the vibronic coupling that produces faster, more efficient energy transfer through the complex under reducing conditions. The growth of coherences across the waiting time and the number of beating frequencies across hundreds of wavenumbers in the power spectra suggest that the beats are excited-state coherences with a mostly vibrational character whose phase relationship is maintained through the energy transfer process. Our results suggest that excitonic energy transfer proceeds through a coherent mechanism in this complex and that the coherences may provide a tool to disentangle coherent relaxation from energy transfer driven by stochastic environmental fluctuations., Competing Interests: The authors declare no competing interest.

Photosynthetic species evolved to protect their light-harvesting apparatus from photoxidative damage driven by intracellular redox conditions or environmental conditions. The Fenna-Matthews-Olson (FMO) pigment-protein complex from green sulfur bacteria exhibits redox-dependent quenching behavior partially due to two internal cysteine residues. Here, we show evidence that a photosynthetic complex exploits the quantum mechanics of vibronic mixing to activate an oxidative photoprotective mechanism. We use two-dimensional electronic spectroscopy (2DES) to capture energy transfer dynamics in wild-type and cysteine-deficient FMO mutant proteins under both reducing and oxidizing conditions. Under reducing conditions, we find equal energy transfer through the exciton 4-1 and 4-2-1 pathways because the exciton 4-1 energy gap is vibronically coupled with a bacteriochlorophyll- a vibrational mode. Under oxidizing conditions, however, the resonance of the exciton 4-1 energy gap is detuned from the vibrational mode, causing excitons to preferentially steer through the indirect 4-2-1 pathway to increase the likelihood of exciton quenching. We use a Redfield model to show that the complex achieves this effect by tuning the site III energy via the redox state of its internal cysteine residues. This result shows how pigment-protein complexes exploit the quantum mechanics of vibronic coupling to steer energy transfer., Competing Interests: The authors declare no competing interest.

Vibronic coupling between pigment molecules is believed to prolong coherences in photosynthetic pigment-protein complexes. Reproducing long-lived coherences using vibronically coupled chromophores in synthetic DNA constructs presents a biomimetic route to efficient artificial light harvesting. Here, we present two-dimensional (2D) electronic spectra of one monomeric Cy5 construct and two dimeric Cy5 constructs (0 bp and 1 bp between dyes) on a DNA scaffold and perform beating frequency analysis to interpret observed coherences. Power spectra of quantum beating signals of the dimers reveal high frequency oscillations that correspond to coherences between vibronic exciton states. Beating frequency maps confirm that these oscillations, 1270 cm -1 and 1545 cm -1 for the 0-bp dimer and 1100 cm -1 for the 1-bp dimer, are coherences between vibronic exciton states and that these coherences persist for ∼300 fs. Our observations are well described by a vibronic exciton model, which predicts the excitonic coupling strength in the dimers and the resulting molecular exciton states. The energy spacing between those states closely corresponds to the observed beat frequencies. MD simulations indicate that the dyes in our constructs lie largely internal to the DNA base stacking region, similar to the native design of biological light harvesting complexes. Observed coherences persist on the timescale of photosynthetic energy transfer yielding further parallels to observed biological coherences, establishing DNA as an attractive scaffold for synthetic light harvesting applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Light-harvesting complexes in photosynthetic organisms display fast and efficient energy transfer dynamics, which depend critically on the electronic structure of the coupled chromophores within the complexes and their interactions with their environment. We present ultrafast anisotropy dynamics, resolved in both time and frequency, of the transmembrane light-harvesting complex LH2 from Rhodobacter sphaeroides in its native membrane environment using polarization-controlled two-dimensional electronic spectroscopy. Time-dependent anisotropy obtained from both experiment and modified Redfield simulation reveals an orientational preference for excited state absorption and an ultrafast equilibration within the B850 band in LH2. This ultrafast equilibration is favorable for subsequent energy transfer toward the reaction center. Our results also show a dynamic difference in excited state absorption anisotropy between the directly excited B850 population and the population that is initially excited at 800 nm, suggesting absorption from B850 states to higher-lying excited states following energy transfer from B850*. These results give insight into the ultrafast dynamics of bacterial light harvesting and the excited state energy landscape of LH2 in the native membrane environment.

Pigment-protein complexes in photosynthetic antennae can suffer oxidative damage from reactive oxygen species generated during solar light harvesting. How the redox environment of a pigment-protein complex affects energy transport on the ultrafast light-harvesting time scale remains poorly understood. Using two-dimensional electronic spectroscopy, we observe differences in femtosecond energy-transfer processes in the Fenna-Matthews-Olson (FMO) antenna complex under different redox conditions. We attribute these differences in the ultrafast dynamics to changes to the system-bath coupling around specific chromophores, and we identify a highly conserved tyrosine/tryptophan chain near the chromophores showing the largest changes. We discuss how the mechanism of tyrosine/tryptophan chain oxidation may contribute to these differences in ultrafast dynamics that can moderate energy transfer to downstream complexes where reactive oxygen species are formed. These results highlight the importance of redox conditions on the ultrafast transport of energy in photosynthesis. Tailoring the redox environment may enable energy transport engineering in synthetic light-harvesting systems.

In photosynthetic organisms, the pigment-protein complexes that comprise the light-harvesting antenna exhibit complex electronic structures and ultrafast dynamics due to the coupling among the chromophores. Here, we present absorptive two-dimensional (2D) electronic spectra from living cultures of the purple bacterium, Rhodobacter sphaeroides, acquired using gradient assisted photon echo spectroscopy. Diagonal slices through the 2D lineshape of the LH1 stimulated emission/ground state bleach feature reveal a resolvable higher energy population within the B875 manifold. The waiting time evolution of diagonal, horizontal, and vertical slices through the 2D lineshape shows a sub-100 fs intra-complex relaxation as this higher energy population red shifts. The absorption (855 nm) of this higher lying sub-population of B875 before it has red shifted optimizes spectral overlap between the LH1 B875 band and the B850 band of LH2. Access to an energetically broad distribution of excitonic states within B875 offers a mechanism for efficient energy transfer from LH2 to LH1 during photosynthesis while limiting back transfer. Two-dimensional lineshapes reveal a rapid decay in the ground-state bleach/stimulated emission of B875. This signal, identified as a decrease in the dipole strength of a strong transition in LH1 on the red side of the B875 band, is assigned to the rapid localization of an initially delocalized exciton state, a dephasing process that frustrates back transfer from LH1 to LH2.