Impact of windbreak design on microclimate in hot regions during cold waves: Numerical investigation.

Winter cold wave adaptation strategies in hot climates due to climate change didn't receive the deserved attention from previous studies. Therefore, this study comprehensively investigates the impact of various windbreak parameters on mitigating winter cold stress in hot steppe-arid climate. A microclimate model for a residential campus was built and validated through on-site measurement on a typical winter day to assess thirty-two scenarios for tree characteristics and spatial configuration windbreak parameters based on PET, wind speed, and Air Temperature (AT). Moreover, four configurations, that had best results on mitigating cold stress in winter, were tested during typical summer conditions to couple the assessment of cold and hot seasons. Additionally, environmental analysis for all scenarios was conducted. The results revealed that the most effective parameters for mitigating cold stress are tree distribution, Leaf Area Density (LAD), row number, spacing, and shape. Double rows of high LAD and medium height trees with small spacing yielded the best cold stress mitigation effect. Furthermore, the windbreak reduced the cold stress in the morning and night by 19.31% and 18.06%, respectively. It reduced AT and wind speed at night by 0.79 °C and 2.56 m/s, respectively. During summer, very hot PET area was reduced by 21.79% and 19.5% at 12:00 and 15:00, respectively.

Erector Spinae Plane Block versus Quadratus Lumborum Block for Postoperative Analgesia after Laparoscopic Resection of Colorectal Cancer: A Prospective Randomized Study.

Background: In recent years, the attention paid to colorectal cancer (CRC) surgery and postoperative analgesia has increased. Objective: The objective of the current study was to compare the impact of ultrasound-guided erector spinae plane block (ESPB) and transmuscular quadratus lumborum block (TQLB) upon providing relief to patients with postoperative pain who underwent laparoscopic resection for CRC. Methods: In this prospective, comparative, and randomized study, the authors considered a total of 60 patients who chose to undergo laparoscopic resection for colorectal cancer. The total number of patients was randomly divided into two groups (such as ESPB and TQLB) so that each group had a total of 30 patients. For the former group, i.e., the ESPB group, 20 ml of 0.25% bupivacaine was administered at each side for bilateral ultrasound-guided erector spinae plane block, while the latter group received the same dose of medicine for bilateral ultrasound-guided transmuscular quadratus lumborum block (TQLB). The researchers recorded the first time to rescue an analgesic, the whole amount of rescue analgesia under consumption in the first 24 hours after the surgical procedure, and associated adverse events. Results: Among the groups considered, the ESPB group took a significantly lengthy time to raise a first request for rescue analgesic (280 ± 15.5 min) in comparison with the TQLB group (260 ± 13.8 min). Likewise, the consumption of overall nalbuphine was remarkably lesser in the ESPB group during the first 24 hours (24 ± 2.5 mg) compared to the TQLB group (30.5 ± 1.55 mg). Conclusion: The analgesic efficacy of ESPB was better when compared to TQLB in terms of time to rescue analgesia and overall opioid consumption during the first 24 hours. This study was registered at ClinicalTrials.gov on 10/10/2022 (registration number: NCT05574283).

Comparison of the effects of transversus thoracic muscle plane block and pecto-intercostal fascial block on postoperative opioid consumption in patients undergoing open cardiac surgery: a prospective randomized study.

BACKGROUND: There is an association exists between cardiac surgery, performed through median sternotomy, and a considerable postoperative pain. OBJECTIVES: The aim of the current study is to compare the effects of transversus thoracic muscle plane block (TTMPB) and pecto-intercostal fascial plane block (PIFB) upon postoperative opioid consumption among the patients who underwent open cardiac surgery. METHODS: The present prospective, randomized, comparative study was conducted among 80 patients who underwent elective on-pump cardiac surgery with sternotomy. The subjects were randomly assigned to two groups with each group containing 40 individuals. For the TTMPB group, bilateral ultrasound-guided TTMPB was adopted in which 20 ml of 0.25% bupivacaine was used on each side. In case of PIFB group, bilateral ultrasound-guided PIFB was adopted with the application of 20 ml of 0.25% bupivacaine on each side. The researchers recorded the first time for rescue analgesia, the overall dosage of rescue analgesia administered in the first 24 h after the operation and the postoperative complications. RESULTS: The PIFB group took significantly longer time to raise the first request for rescue analgesia (7.8 ± 1.7 h) than the TTMPB group (6.7 ± 1.4 h). Likewise, the PIFB group subjects had a remarkably lower 'overall morphine usage' in the first 24 h after the operation (4.8 ± 1.0 mg) than TTMPB group (7.8 ± 2.0 mg). CONCLUSION: Bilateral ultrasound-guided PIFB provided a longer time for the first analgesic demand than bilateral ultrasound-guided TTMPB in patients undergoing open cardiac surgery. In addition to this, the PIFB reported less postoperative morphine usage than the TTMPB and increases satisfaction in these patients. TRIAL REGISTRATION: This study was registered at Clinical Trials.gov on 28/11/2022 (registration number: NCT05627869).

Non-penetrating deep sclerectomy versus combined trabeculotomy-trabeculectomy in primary congenital glaucoma.

Background: The primary mode of therapy in children with primary congenital glaucoma (PCG) and mild or no corneal edema is goniotomy, which has a high success rate. However, in developing countries, the diagnosis of PCG is usually delayed, and corneal cloudiness interferes with goniotomy. Therefore, trabeculotomy may be the best choice in such eyes. We compared the short-term efficacy and safety of primary combined trabeculotomy-trabeculectomy (primary CTT) with that of non-penetrating deep sclerectomy (NPDS) in managing PCG. Methods: This prospective, randomized, comparative study included patients with PCG referred to Al-Azhar University Hospitals within a 1-year period. Eyes were randomly allocated to one of two groups: eyes in NPDS group underwent NPDS, and those in primary CTT group underwent primary CTT. Baseline and frequent postoperative assessments of intraocular pressure (IOP), cup-to-disc ratio (C/D ratio), corneal diameter, and axial length were performed for up to 6 months. The success rates were recorded in both groups. Results: Forty eyes of 26 patients were included, with 20 eyes allocated to each group. The mean (standard deviation) age of all patients was 12.9 (9.5) months, with comparable ages and sex ratios between groups (both P > 0.05). Both groups demonstrated a significant reduction in IOP and C/D ratio at each postoperative visit compared to the baseline visit (all P < 0.001), with no significant difference detected between the groups (all P > 0.05), except for a significantly lower IOP in NPDS group at 1 month (P < 0.05). The corneal diameter and axial length were comparable between groups at baseline and remained unchanged at all postoperative visits (all P > 0.05). The groups had comparable success rates (P > 0.05). No serious complications were detected. Conclusions: CTT and NPDS both yielded reasonable IOP control and reversal of cupping in eyes with PCG. We observed equal effectiveness of the surgical procedures without major safety concerns. Further large-scale clinical trials with longer follow-up periods are needed to verify our preliminary findings.

Comparative study of dexmedetomidine versus fentanyl as adjuvants to bupivacaine in ultrasound-guided transversus abdominis plane block in patients undergoing radical cystectomy: a prospective randomised study.

BACKGROUND: Transversus abdominis plane (TAP) block is beneficial for pain management after conducting abdominal surgery. OBJECTIVE: To compare the outcomes of dexmedetomidine and fentanyl, as adjuvants to bupivacaine, for ultrasound-guided TAP block analgesia among patients undergoing radical cystectomy for postoperative pain management. METHODS: This prospective, randomised, comparative study included a total of 60 patients, who underwent radical cystectomy. Participants were randomly divided into three categories with 20 subjects each; group B had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 2 ml normal saline; group BF had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 1 µg/kg fentanyl dissolved in 2 ml normal saline and group BD had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 1 µg/kg dexmedetomidine dissolved in 2 ml normal saline.The researchers recorded the time taken for first rescue analgesia, total analgesic dose in the first 24 h after surgery, patient satisfaction, sedation score, and postoperative complications. RESULTS: The time taken for first rescue analgesia was significantly lengthier in group (BD) (8.90 ± 2.47) than (BF) (6.50 ± 1.43) and (B) (4.40 ± 1.05) groups. The total nalbuphine consumption, during the first 24 h, was significantly lower in (BD) (0.15 ± 0.00) group compared to (BF) (0.20 ± 0.07) and (B) (0.24 ± 0.08) groups. CONCLUSION: In comparison with fentanyl, as an adjuvant to bupivacaine, dexmedetomidine was found to be associated with prolonged postoperative analgesia, less postoperative pain scores and low opioid consumption. TRIAL REGISTRATION: This study was registered at Clinical Trials.gov on 23 March 2020 (registration number: NCT04318158).

2-Hydroxyestradiol Overcomes Mesenchymal Stem Cells-Mediated Platinum Chemoresistance in Ovarian Cancer Cells in an ERK-Independent Fashion.

Ovarian cancer (OC) is the second most common type of gynecological malignancy. Platinum (Pt)-based chemotherapy is the standard of care for OC, but toxicity and acquired chemoresistance has proven challenging. Recently, we reported that sensitivity to platinum was significantly reduced in a co-culture of OC cells with MSC. To discover compounds capable of restoring platinum sensitivity, we screened a number of candidates and monitored ability to induce PARP cleavage. Moreover, we monitored platinum uptake and expression of ABC transporters in OC cells. Our results showed that 2-hydroxyestradiol (2HE2), a metabolite of estradiol, and dasatinib, an Abl/Src kinase inhibitor, were significantly effective in overcoming MSC-mediated platinum drug resistance. Dasatinib activity was dependent on ERK1/2 activation, whereas 2HE2 was independent of the activation of ERK1/2. MSC-mediated platinum drug resistance was accompanied by reduced intracellular platinum concentrations in OC cells. Moreover, MSC co-cultured with OC cells resulted in downregulation of the expression of cellular transporters required for platinum uptake and efflux. Exposure to 2HE2 and other modulators resulted in an increase in intracellular platinum concentrations. Thus, 2HE2 and dasatinib might act as sensitizers to restore platinum drug sensitivity to OC cells and thus to limit TME-mediated chemoresistance in OC.

Flavonoids Restore Platinum Drug Sensitivity to Ovarian Carcinoma Cells in a Phospho-ERK1/2-Dependent Fashion.

Ovarian cancer (OC) is the second most common type of gynecological malignancy; it has poor survival rates and is frequently (>75%) diagnosed at an advanced stage. Platinum-based chemotherapy, with, e.g., carboplatin, is the standard of care for OC, but toxicity and acquired resistance to therapy have proven challenging. Despite advances in OC diagnosis and treatment, approximately 85% of patients will experience relapse, mainly due to chemoresistance. The latter is attributed to alterations in the cancer cells and is also mediated by tumor microenvironment (TME). Recently, we reported the synthesis of a platinum (IV) prodrug that exhibits equal potency toward platinum-sensitive and resistant OC cell lines. Here, we investigated the effect of TME on platinum sensitivity. Co-culture of OC cells with murine or human mesenchymal stem cells (MS-5 and HS-5, respectively) rendered them resistant to chemotherapeutic agents, including platinum, paclitaxel and colchicine. Platinum resistance was also conferred by co-culture with differentiated murine adipocyte progenitor cells. Exposure of OC cells to chemotherapeutic agents resulted in activation of phospho-ERK1/2. Co-culture with MS-5, which conferred drug resistance, was accompanied by blockage of phospho-ERK1/2 activation. The flavonoids fisetin and quercetin were active in restoring ERK phosphorylation, as well as sensitivity to platinum compounds. Exposure of OC cells to cobimetinib-a MEK1 inhibitor that also inhibits extracellular signal-regulated kinase (ERK) phosphorylation-which resulted in reduced sensitivity to the platinum compound. This suggests that ERK activity is involved in mediating the function of flavonoids in restoring platinum sensitivity to OC co-cultured with cellular components of the TME. Our data show the potential of combining flavonoids with standard therapy to restore drug sensitivity to OC cells and overcome TME-mediated platinum drug resistance.

The potential use of natural products to negate hepatic, renal and neuronal toxicity induced by cancer therapeutics.

Different types of chemotherapeutics are used for cancer treatment. These drugs act on several signal pathways, lead to programmed cell death, and damage cancer cells. Although many specific mechanisms of action have been suggested for chemotherapeutics, there are still gaps in understanding their effects. They may affect different components of the cell, particularly proteins with specific functions, such as enzymes. Recently, targeted and immuno therapies were introduced for treatment of different cancers. However, many cancer patients still depend on traditional and well-known drugs. Doxorubicin and platinum-based drugs are among the most frequently used chemotherapeutics. They are highly cytotoxic for cancer cells, but they also act on healthy cells. Hence, it is crucial to understand the mechanisms involved in order to decrease their side effects. Natural products, many of which are also available over-the-counter, may be considered to decrease various cancer drug-induced side effects. This review focuses on the use of these compounds to overcome side effects of chemotherapeutics, primarily doxorubicin and cisplatin, in the liver, kidney, and neuronal systems.

Streptokinase Versus Unfractionated Heparin Nebulization in Patients With Severe Acute Respiratory Distress Syndrome (ARDS): A Randomized Controlled Trial With Observational Controls.

OBJECTIVE: To examine and compare nebulizing heparin versus streptokinase for reversing alveolar collapse nonresponsive to recruitment. DESIGN: A clinical trial at a tertiary intensive care unit (ICU). Sixty patients with severe acute respiratory distress syndrome (ARDS) (PaO2/FIO2 <100) nonresponsive to recruitment maneuver (RM), prone position, and neuromuscular block (NMB) were randomized into intervention arms or the standard-of-care arm. SETTING: The ICU at Beni-Suef University Hospital. PARTICIPANTS: Sixty patients with severe ARDS (PaO2/FIO2 <100) nonresponsive to RM, PP, and NMB. INTERVENTIONS: Nebulized heparin (10,000 IU/4 h), nebulized streptokinase (250,000 IU/4 h), and conservative management. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the change in PaO2/FIO2; the secondary outcomes included the change in compliance, plateau pressure, coagulation, and ICU mortality. The PaO2/FIO2 was significantly higher in the streptokinase group from day 1 to day 8 compared to the heparin and standard-of-care groups. Streptokinase produced PaO2/FIO2>100 at day 1, >200 at day 5, and >300 at day 7. The heparin group achieved a PaO2/FIO2 >100 at day 5 but remained <200 until day 8. The standard-of-care group did not achieve a PaO2/FIO2>100 after 8 days. Streptokinase significantly reduced plateau pressure and improved compliance at day 8. Only streptokinase decreased PaCO2 (p < 0.0001). Moreover, ICU mortality was significantly lower in streptokinase patients compared to other groups. Additionally, no heparin-induced thrombocytopenia was observed in all groups. CONCLUSION: Inhaled streptokinase serves as rescue therapy in patients with severe ARDS with improving oxygenation and lung mechanics more quickly than heparin or conventional management.

Template Assisted Microwave Synthesis of rGO-ZrO2 Composites: Efficient Photocatalysts Under Visible Light.

In this research, cetyltetraethyl ammonium bromide template assisted microwave procedure was utilized to synthesize reduced graphene oxide-zirconia (rGO-ZrO2) nanocomposites by varying the rGO composition (1, 2, 5 and 10 wt%). The physico-chemical characteristics of the nanocomposites were studied using X-ray diffraction (XRD), Raman, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), diffusive reflectance ultraviolet-visible (DRUV-vis), X-ray photoelectron spectroscopy (XPS) and N2-physisorption techniques. The results from XRD, Raman and DSC studies indicate that the increase in rGO concentration resulted in the delay in ZrO2 crystallization temperature and alteration of ZrO2 phase from monoclinic to tetragonal due to an effective incorporation of rGO nanosheets in ZrO2 structure. The rGO loading also have an influence in the morphology of nanocomposites, as sample with 10 wt% rGO possessed unique monolith like morphology with macro pores. All the nanocomposites were utilized as photocatalysts for degradation of crystal violet dye in visible light irradiation. The rGO-ZrO2 nanocomposites showed high reaction rates; the nanocomposite with 5 wt% rGO showed the superior photocatalytic performance as this sample possessed low band gap energy, high surface area, pore volume and presence of surface rGO-ZrO2 interactive species as well as the reactive -OH groups. In addition, the synthesized nanocomposites exhibited excellent recyclability for photocatalytic degradation.

Addition of Neostigmine and Atropine to Conventional Management of Postdural Puncture Headache: A Randomized Controlled Trial.

BACKGROUND: Postdural puncture headache (PDPH) lacks a standard evidence-based treatment. A patient treated with neostigmine for severe PDPH prompted this study. METHODS: This randomized, controlled, double-blind study compared neostigmine and atropine (n = 41) versus a saline placebo (n = 44) for treating PDPH in addition to conservative management of 85 patients with hydration and analgesics. The primary outcome was a visual analog scale score of ≤3 at 6, 12, 24, 36, 48, and 72 hours after intervention. Secondary outcomes were the need for an epidural blood patch, neck stiffness, nausea, and vomiting. Patients received either neostigmine 20 µg/kg and atropine 10 µg/kg or an equal volume of saline. RESULTS: Visual analog scale scores were significantly better (P< .001) with neostigmine/atropine than with saline treatment at all time intervals after intervention. No patients in the neostigmine/atropine group needed epidural blood patch compared with 7 (15.9%) in the placebo group (P< .001). Patients required no >2 doses of neostigmine/atropine. There were no between-group differences in neck stiffness, nausea, or vomiting. Complications including abdominal cramps, muscle twitches, and urinary bladder hyperactivity occurred only in the neostigmine/atropine group (P< .001). CONCLUSIONS: Neostigmine/atropine was effective in treating PDPH after only 2 doses. Neostigmine can pass the choroid plexus but not the blood-brain barrier. The central effects of both drugs influence both cerebrospinal fluid secretion and cerebral vascular tone, which are the primary pathophysiological changes in PDPH. The results are consistent with previous studies and clinical reports of neostigmine activity.

Efficacy of Dexmedetomidine versus Ketofol for Sedation of Postoperative Mechanically Ventilated Patients with Obstructive Sleep Apnea.

Patients with sleep apnea are prone to postoperative respiratory complications, requiring restriction of sedatives during perioperative care. We performed a prospective randomized study on 24 patients with obstructive sleep apnea (OSA) who underwent elective surgery under general anesthesia. The patients were equally divided into two groups: Group Dex: received dexmedetomidine loading dose 1 mcg/kg IV over 10 min followed by infusion of 0.2-0.7 mcg/kg/hr; Group KFL: received ketofol as an initial bolus dose 500 mcg/kg IV (ketamine/propofol 1 : 1) and maintenance dose of 5-10 mcg/kg/min. Sedation level (Ramsay sedation score), bispectral index (BIS), duration of mechanical ventilation, surgical intensive care unit (SICU) stay, and mean time to extubation were evaluated. Complications (hypotension, hypertension, bradycardia, postextubation apnea, respiratory depression, and desaturation) and number of patients requiring reintubation were recorded. There was a statistically significant difference between the two groups in BIS at the third hour only (Group DEX 63.00 ± 3.542 and Group KFL 66.42 ± 4.010, p value = 0.036). Duration of mechanical ventilation, SICU stay, and extubation time showed no statistically significant differences. No complications were recorded in both groups. Thus, dexmedetomidine was associated with lesser duration of mechanical ventilation and time to extubation than ketofol, but these differences were not statistically significant.

Acidic Peptizing Agent Effect on Anatase-Rutile Ratio and Photocatalytic Performance of TiO2 Nanoparticles.

TiO2 nanoparticles were synthesized from titanium isopropoxide by a simple peptization method using sulfuric, nitric, and acetic acids. The effect of peptizing acid on physicochemical and photocatalytic properties of TiO2 powders was studied. The structural properties of synthesized TiO2 powders were analyzed by using XRD, TEM, N2-physisorption, Raman, DR UV-vis, FTIR, and X-ray photoelectron spectroscopy techniques. The characterization results showed that acetic acid peptization facilitated the formation of pure anatase phase after thermal treatment at 500 °C; in contrast, nitric acid peptization led to a major rutile phase formation (67%). Interestingly, the sample peptized using sulfuric acid yielded 95% anatase and 5% rutile phases. The photocatalytic activity of synthesized TiO2 nanoparticles was evaluated for degradation of selected organic dyes (crystal violet, methylene blue, and p-nitrophenol) in aqueous solution. The results confirmed that the TiO2 sample peptized using nitric acid (with rutile and anatase phases in 3:1 ratio) offered the highest activity for degradation of organic dyes, although, TiO2 samples peptized using sulfuric acid and acetic acid possessed smaller particle size, higher band gap energy, and high surface area. Interestingly, TiO2 sample peptized with nitric acid possessed relatively high theoretical photocurrent density (0.545 mAcm-2) and pore diameter (150 Å), which are responsible for high electron-hole separation efficiency and diffusion and mass transportation of organic reactants during the photochemical degradation process. The superior activity of TiO2 sample peptized with nitric acid is due to the effective transfer of photogenerated electrons between rutile and anatase phases.

Posterior vitreous detachment and retinal detachment after implantation of the Visian phakic implantable collamer lens.

INTRODUCTION: To evaluate the vitreoretinal complications in myopes after Visian implantable collamer lenses (ICL) implantation. MATERIALS AND METHODS: This is a retrospective, observational, non-comparative clinical study that evaluated 617 consecutive myopes who underwent ICL implantation at the Department of Refractive Surgery, Yemen Magrabi Hospital, Sana'a, Yemen between July 2006 and May 2010. Follow up ranged from 6 months to 40 months. Preoperative and postoperative patient evaluation included manifest and cycloplegic refractions, uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), slit-lamp biomicroscopy, intraocular pressure and dilated retinal examination. Investigations included corneal topography, central corneal thickness, anterior chamber depth and white to white diameter. Retinal diseases and complications were recorded and analyzed preoperatively and postoperatively. RESULTS: Preoperatively, 61 (9.9%) eyes had posterior segment pathology requiring prophylactic laser photocoagulation. One eye developed spontaneous rhegmatogenous retinal detachment (RRD), one eye developed traumatic retinal detachment and two eyes required laser treatment postoperatively. The overall retinal detachment rate post-ICL was 0.32%. CONCLUSIONS: Posterior segment complications are rare after ICL implantation but dilated vitreoretinal assessment is important before and after the procedure. Patients with suspicious retinal lesions need a comprehensive vitreoretinal evaluation by a retinal specialist. If a patient develops floaters or blurry vision he/she requires further assessment by a vitreoretinal specialist.

Direct formation of thermally stabilized amorphous mesoporous Fe2O3/SiO2 nanocomposites by hydrolysis of aqueous iron III nitrate in sols of spherical silica particles.

Nanocomposite materials containing 10% and 20% iron oxide/silica, Fe2O3/SiO2 (w/w), were prepared by direct hydrolysis of aqueous iron III nitrate solution in sols of freshly prepared spherical silica particles (Stöber particles) present in their mother liquors. This was followed by aging, drying, calcination up to 600 degrees C through two different ramp rates, and then isothermal calcinations at 600 degrees C for 3 h. The calcined and the uncalcined (dried at 120 degrees C) composites were characterized by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), N2 adsorption/desorption techniques, and scanning electron microscopy as required. XRD patterns of the calcined composites showed no line broadening at any d-spacing positions of iron oxide phases, thereby reflecting the amorphous nature of Fe2O3 in the composite. The calcined composites showed nitrogen adsorption isotherms characterizing type IV isotherms with high surface area. Moreover, surface area increased with the increasing of the iron oxide ratio and lowering of the calcination ramp rate. Results indicated that iron oxide particles were dispersed on the exterior of silica particles as isolated and/or aggregated nanoparticles. The formation of the title composite was discussed in terms of the hydrolysis and condensation mechanisms of the inorganic FeIII precursor in the silica sols. Thereby, fast nucleation and limited growth of hydrous iron oxide led to the formation of nanoparticles that spread interactively on the hydroxylated surface of spherical silica particles. Therefore, a nanostructured composite of amorphous nanoparticles of iron oxide (as a shell) spreading on the surface of silica particles (as a core) was formed. This morphology limited the aggregation of Fe2O3 nanoparticles, prevented silica particle coalescence at high temperatures, and enhanced thermal stability.

Early stages of styrene-isoprene copolymerization in gas phase clusters probed by resonance enhanced multiphoton ionization.

We present direct evidence for the formation of the covalent bonded styrene (isoprene)(2) oligomer and the isoprene dimer ions following resonance ionization of the gas phase styrene-isoprene binary clusters. The application of resonance ionization to study polymerization reactions in clusters provides new information on the structure and mechanism of formation of the early stages of polymerization and holds considerable promise for the discovery of new initiation mechanisms and for the development of novel materials with unique properties.